Chemical Technology in Pre-treatment

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T EXT IL E SC IEN C E AN D T EC H N O L O G Y 12

C H E M I C A L T E C H N O L OGYIN THE PRE-TREATME NTPROCESSES OF TEXTILES



TEXTILE SCIENCE AND TECHNOLO GY

V o l u me 1

V o l u me 2

V o l u m e 3

V o l u me 4V o l u m e 5

V o l u me 6V o l u me 7

V o l u me 8V o l u m e 9Vo lume 10Volume 11

Vo lume 12

Open-end Sp inn ing by V.Rohlena et a l.

Processing of Polyester Fibres by O. Pajgrt and B. Reichst~ dter

Shu t t le less We av ing Mach ines by O. Talava~,ek and V. Svat~/

F luo rescen t B r igh ten ing Agen ts by R. W i l l iam sonPolypropy lene F ibres - Sc ience and Techno logy by M. Ah m e dProduct ion and App l ica t ions o f Po lypropy lene Text i les by O. Pajgrt et a l.Ab s o r b e n c y edi ted by P.K. Cha tter jee

Need le Punch ing Te x t il e Techno logy by V. Mr~t ina and F. FejglIndust r ia l Tex t i les edi ted by J . Sv6dovaModi f ied Po lyes ter F ibres by J . Mi l i t k~ et a l.Text i le Process ing and Proper t ies : Prepara t ion , Dye ing, F in ish ingand Per formance by T.L. Vigo

Chemica l Techno logy in the Pre- t rea tment Processes

of Text i les by S.R. Karm akar



T E X T I L E S C I E N C E A N D T E C H N O L O G Y 1 2

C H E M I C A LT E C H N O L O G Y I N

T H E P R E - T R E A T M E N T

P R O C E S S E S O FT E X T I L E S

B Y

S .R . K A R M A K A RProfessor of Textile ChemistryCollege of Textile TechnologySerampore Hooghly West BengalIndia

1 9 9 9

i

E L S E V I E R

A m s t e r d a m - L a u s a n n e - N e w Y o r k - O x f o r d - S h a n n o n - S i n g a p o r e - T o k y o



ELSEVIER SCIENC E B.V.

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P R E F A C E

Text i le chem ica l process ing today, pa r ticu la rly the pre - t rea tmen t processes requi re

a h ighly sophis t ica ted technology and engineer ing to achieve the we l l know n conceptso f " R igh t f ir s t t im e , R ig th t e ve r y t im e a nd R igh t on t im e " p r oc e ss ing a nd p r oduc t ion .

C h e m i c a l p r e - t re a t m e n t m a y b e b r o a d l y d e f in e d a s a p r o c e d u r e m a i n l y c o n c e r n e d

with the remov a l of na tura l a s we l l a s added im pur i t ie s in fabr ic to a leve l necessa ry

f o r good wh i t e ne ss a nd a bso r ba ncy by u t il ism g m in im um t im e , e ne r gy a nd c he m ica l

as we l l a s w a te r .

Th i s book d i sc usse s the funda m e n ta l a spe c t s o f c he m is t ry , c he m ic a l t e c hno logy

a nd m a c h ine r i e s invo lve d in the va r ious p r e - t r e a tm e n t p r oc e ss o f t e x t i l e s be f o r e

subse que n t dy e ing , p r in t ing a nd f in i sh ing . W i th the in t r oduc t ion o f ne w e r f ib r es ,spe c ial ty c he m ic a ls , im pr ove d t e c hno logy a nd soph i s ti c a te d m a c h ine r i e s de ve lope d

dur ing the la s t decade , a l l a t tempts have been made to f i l l a gap in th is a rea of

t e c hno logy . N e w c ha p te r s a re in t e g r at e d a nd in t roduc e d to upgr a de the in f o r m a t ion

and the subjec t ma t te r and contents a re so chosen tha t i t wi l l pe rmi t the teacher to

r e a r r a nge un i t s t o su i t t he ne e ds o f ind iv idua l g r oup s o f s tude n ts . E f f o r t s a r e a lso

m a de to p r ov ide a n in - de p th e xpos i t ion o f the top ic w i th a r e v ie w o f the m os t

e xc i t ing r e c e n t de ve lo pm e n t s in the r a p id ly m o v ing f ie ld . B u t the r e a l s t r e ng th o f

th is book i s i ts c l e ar pe rc e p t ion o f a m ple ba c kgr ou nd de sc r ip t ion , wh ic h wi l l e nab le

to und e r s t a nd m os t c u r r e n t j ou r na l s e m pow e r ing the re a de r to st a y a b r e a s t o f t he

la tes t advan ces in the f ie ld .

The in t e r p la y be tw e e n f ib r e s tr uc tu re , m o r ph log y a nd c he m is t r y i s a n in te g r a l

pa r t o f a ll p r e - t r e a tm e n t p r oc e sse s a nd in C ha p te r 1 a n a t t e m pt i s m a de to c ove r the

m o s t up - to - da te in f o r m a t ion r e ga r d ing a ll t he p r inc ipa l c l a s se s o f f ib re s , v i e we d in

the l ight of resea rch and com merc ia l explo i ta t ion . C hapte r 2 is devoted to mechanica l

f a b r i c p r e pa r a t ion be f o r e c he m ic a l p r oc e s s ing c om m e nc e s to a c h ie ve sm oo th a ndt r oub le f r ee r e su l t s in subse que n t d ye ing a nd f in ish ing . C ha p te r 3 d i sc usse s the

c he m is t r y o f d i f f er e n t s i z ing a ge n t s w i th r e spe c t t o the i r r e m o va l f r om the f a b r ic s .

C ha p te r 4 c ove r s a pu r i f y ing t r e a tm e n t o f te x t i l es to re duc e the a m oun t o f na tu r a l

im pu r i t ie s su f f i c ie n t ly to e na b le l e ve l a nd r e p r oduc ib le dye ings a nd f in i sh ing to be

p r oduc e d . S pe c ia l ty c he m ic a l s ha ve ve r y h igh va lue in the c he m ic a l p r oc e s s ing o f

t e x t i le s a nd the a pp l i c a t ions o f c he m ic a l a ux i l i a ri e s a r e inc lude d in the r e le ve n t

p r oc e sse s . C ha p te r 5 de sc r ibe s the va r ious m a c h ine r i e s tha t ha ve be e n de ve lope d



vi Preface

fo r t he pu r i fy ing opera ti ons . Chap te r 6 dea ls wi th the de t a il ed unders t and ing o f

var ious b leac hing agents and thei r m ech anism s or m ode o f ac t ion on var ious f ibres .The chem is t ry , t echno logy and ca re gu ides a re i nc luded sepera t e ly fo r each f i b re

and b l ended f i be r f ab r i c s . Ne w m ach ine r i es have been deve loped fo r the b l each ing

of tex t i l es and Ch apter 7 looks a t the mac hiner ies involved in such process . Re cent

t echno log i ca l advances o f me rce r i z ing and hea t - s e tt i ng o f t ex t il e s a re i nc luded i n

Chapters 8 and 9 respect ively . Text i le f ibres do not appear perfect ly whi te even

af t e r chem ica l b l each ing and Cha p te r 10 desc r ibes the chem is t ry and m echa n i sm

of opt ica l br ighten ing agents as wel l as thei r appl ica t ions to var ious k inds o f fibers.

Al l ser ious ef for t s have been d i rected in Cha pter 11 towards shor tened or com binedpre - t r ea tmen t p roces s ing i n o rde r t o min imize energy consumpt ion . Chemica l

deg rad a t i on o r dam ages caused by imp roper app l i ca ti on o f p roces ses , e r roneous

concep t o f p rocedure , f au l t y opera t i on o f mach ines and chemica l s a re c r i t i ca l l y

rev i ew ed in Chap te r 12. A chang ing con cern i n ma t t e r s re l a t ing t o env i ronm en ta l

po l lu t i on f rom p re - t r ea tmen t p roces ses i nvo lved i n t ex t i l e mi l l s and p roces s ing

house in par t icu lar i s increas ingly dem ande d and thus a ll these var ied deve lopm ents

in l eg i s l a t i o n , i n ana lys is and s t andards and in tr ea tmen t s a re i nc luded i n Chap te r

13. P re - t r ea tmen t o r su r face m od i f i ca t ion o f tex t i le s wi th l ow t em pera tu re g low-

discharg es or p lasm a i s of great in teres t in near fu ture and Cha pter 14 d i scusses i t s

app l i ca t ion as an a l t e rna t ive t o conven t iona l t echn iques. Enzy mat i c p re - t r ea tmen t

( a b io log i ca l app roach) i s becom ing an impor t an t comm erc i a l p roces s and Chap te r

15 conta ins the dev elopm ent in the f ie ld of enzym e t rea tments for t ex t il es . Tes t ing ,

ana lyses and e va lu t a ti on o f t he e f f ic i ency o f p roces ses p resen t t he t ime dom ain

approac h t o mo dem proces s con t ro l, wh ich a l lows fo r the fo rmat ion o f p rec i s e

per fo rm ance ob j ec t ives t ha t can be examined . Thus , Chap te r 16 wi l l be a va luab l eresou rce for prac t ic ing proc ess cont ro l t echno logis t s and s tudents.

I hope the reader wi l l f ind the bo ok in teres t ing and usefu l wi th sugg es ted

re fe rences i n each chap t e r a long w i th s imp l if i ed f low d i ag ram s show ing va r ious

p roces ses and mach ine r i e s i nvo lved i n p re - tr ea tmen t techno logy o f t ex ti le s . No

s ingle tex t can be suff ic ient unto i t se l f . A ny cons t ruct ive sugges t ions and comm ents

are therefo re w elcom e for fu ture reves ion s and correct ions .

S e r am p o r e ,Ho ogh l y , W e s t B e n ga l ,

(India) , Ap ri l 1999.

S a m i r R an j an K a r m a k a r



C O N T E N T S

P r e f a c e

Chapter 1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

K i n d s o f f ib r e s

In t roduct ion

Class i f ica t ion of f ibres

Chem ica l compos i t i on , mo rpho logy and s truc tu re o f co tt on

1 . 3 . 1 Co t ton impur i ti e s

Natura l pro te in f ibres

1 . 4 . 1 Mo lecu l a r s truc tu re o f woo l f ib res

1 .4 .2 Imp ur i t i es in raw wo ol

1 .4 .3 M orp holo gy and chem ical s t ructure of s i lk

Lon g v ege t ab l e f ib res

1 .5 .1 Flax ( l inen)

1 .5 .2 Remie

1.5 .3 Hemp

1.5.4 JuteReg enera t ed na tu ra l f ib res

1 . 6 . 1 C u p r a m m o n i u m r a yo n

1.6 .2 Viscos e rayon

1.6.3 Ac etate f ibres

1 .6 .4 Re gen erated pro te in f ibres

Synthet ic f ibres

1 . 7 . 1 Po lyes t e r

1 .7 .2 Nylon1.7.3 Ac ryl ic f ibres

1.7.4 Olefin f ibres

Miscel laneous synthet ic f ibres

1 . 8 . 1 Ch lo ro f ib res

1.8.2 Po ly(v iny l alcoho l) f ibres

1 .8 .3 Elas tom eric f ibres

1 .8 .4 Ca rbon f ibres

1 .8 .5 PT O f ibres (Enk atherm )

1

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viii Contents

1.8.6

Refe rences

Other synthet ic f ibres 42

4 4

Chapter 2

2.1

2 .2

2.3

2 .4

2.5

2.6

P r e p a r a t i o n b e f o r e c h e m i c a l p r o c e s s e s

In t roduct ion

Inspect ion

S e w i n g

Me chan ica l c l ean ing o f f ab r ic s

2 .4 .1 Brushing

2 . 4 .2 Cropp ing and shea r ingS inge ing

2.5 .1 S ing eing d i f ferent k inds of f ibres fabr ics

2 .5 .2 Pla te s ingeing ma chine

2 . 5. 3 Ro ta ry cy l i nder mac h ine

2 . 5 .4 Gas s i nge ing ma ch ine

2 .5 .5 S inge ing c i rcular kni t fabr ics

Proces s s equence

2.6.1 Co t ton fabr ic on k ier

2 .6 .2 Co t ton fabr ic on J -Box

2.6 .3 Co t ton fabr ic on pad-ro l l / therm oreact ion cha m ber

(T.R.C.)

2 . 6. 4 Co t ton fab r ic on Jumbo j i gger

2 .6 .5 Kni t ted cot ton goods

2 .6 .6 W ool len fabr ics

2.6.7 Si lk fabrics

2 .6 .8 Polye s ter fabr ics

2 .6 .9 N ylon fabr ics

2 .6 .10 Polyes ter /co t ton b lends

2 .6.11 Polyes ter /v i scose b lends

2 .6 .12 Polyes ter /w ool b lends

2 .6 .13 Diace ta te /v i scose b lends

4 9

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Chapter 3 D e s i z i n g3.1 In t roduct ion

3 . 2 M ethods o f des i z ing

3.2.1 Ro t s teep ing

6 969

71

72



Contents ix

3.2.2 Acid desizing

3.2.3 Enzymatic desizing3.2.4 Desizing with oxidising agents

3.3 Desizing of synthetic fabrics and their blends

3.4 Desizing machineries

References

72

7275

77

79

84

Chapter4 Scouring4.1 Introduction

4.2 Mechanism of removal of impurities4.3 Scouting of cotton in alkaline agents

4.3.1 The lime-soda boil

4.3.2 The caustic soda boil

4.3.3 The soda-ash boil

4.3.4 The mixture of caustic soda and soda-ash boil

4.3.5 The soap/detergent-soda-ash boil

4.3.6 Sequestering agents

4.3.7 Builders

4.3.8 Fibre protecting reducing agents

4.3.9 Mild oxidising agents

4.3.10 Water insoluble solvents

4.4 Surfactants

4.4.1 Anionic surfactants

4.4.2 Cationic surfactants

4.4.3 Non-ionic surfactants

4.4.4 Amphoteric surfactants

4.4.5 Blends of surfactants

4.4.6 Surfactants as wetting agent

4.4.7 Surfactants as detergent (scouting agent)

4.4.8 Emulsion scouting

4.5 Solvent scouting

4.6 Scouting of raw wool

4.6.1 Emulsion scouting4.6.2 Suint scouring

4.6.3 Solvent extraction scouring

4.6.4 Refrigeration process

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x Contents

4 .7 Sco ut ing woo l yarn and fabr ic

4 .7.1 Se t t ing and scou t ing o f woo l yarn4 .7 .2 Crabb ing ( se tt ing) o f woo l len fabr ic

4 .7 .3 Po t t ing o f wo ol len fabr ic

4 .7 .4 Sco ut ing o f woo l fabr ic

4 .8 Ca r b o n i s in g o f wo o l

4 .9 Deg u m m in g o f s ilk

4 .9 .1 Deg u m m in g in wa te r

4 .9 .2 Deg um m ing wi th a lka l i and ac id

4 .9.3 Deg u m m in g wi th so ap4 .9 .4 Deg um m ing wi th syn the t ic de te rgen ts

4 .9.5 En zy m a t i c d eg u m m in g

4 . 9. 6 F o a m d e g u m m i n g

4 .9 .7 Par t ia l degu m m ing

4 .9.8 W ash in g o f d eg u m m ed s i lk

D e g u m m i n g o f r em i e

Sco u t in g o f l in en

Sco u t in g o f j u t e

Sco ut ing o f syn the t ic -po lym er f ib res

4 .13 .1 Po lyes te r

4 .1 3 .2 Ny lo n

4.13.3 Poly acry lonitr i le f ibres

4 .13 .4 Aceta te f ib res

4 .13 .5 Re genera ted ce l lu lose

4 .13 .6 Tex tur ised fabr ics

Sco ut ing o f b lended f ib re fabr ics

4.14.1 Polyster /cotton

4 .14 .2 Po lyes te r /wool

4 .14 .3 Po lyes te r /acry l ic

4 .14 .4 Acry l ic /wool

4 .14 .5 Acry l ic /ce l lu los ics

4 .14 .6 Aceta te /wool

4 .14 .7 Blends con ta in ing v iscose4.14.8 Polyester /si lk

4 .14 .9 Blends con ta in ing case in

R e f e r e n c e s

4 .1 0

4.11

4 .1 2

4 .13

4 .14

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Contents xi

Chapter5

5.15.2

5.3

5.4

5.5

5.6

Sc ou r i ng m ac h i ne r ie s

In t roduct ionBatch t ype ( rope) s cou t ing m ach ines

5 .2.1 Lo w pressure k ier

5 .2 .2 High pressure k ier

5 .2 .3 Ja f fe r son-W alker ' s k i e r

5 . 2 .4 Gebau er k i e r

Ba t ch t ype (open-wid th ) s cou t ing mach ines

5 .3.1 M athe r and Pla t t hor izonta l k ier

5 .3 .2 Jackso n k ier5 .3 .3 J ig process

S emi -con t inuous s cou t ing mach ines

5 .4 .1 Padd -ro l l sys tem

5 . 4 .2 Padd-s t eam -ro l l sys t em

5.4 .3 Padd -ro l l on perfora ted cyl inder

Con t inuous s cour ing mach ines

5 .5 .1 Satura tor J -Box -rope w asher

5 . 5 .2 Open -wid th ro l le r s t eamer

5 . 5. 3 Ba t ch o r r e -ba t ch ing sys t em

5 . 5 .4 Vapor loc sys t em

5.5 .5 High pressure Kl ienew efer ro l ler s team er

5 . 5 .6 Co nvey er s t o rage s t eamer sys t em

5 . 5 .7 Ro l l e r -bed s t eamer wi th p re - swe l l ing t im e

5 . 5 .8 Con t inuous r e l ax ing / scour ing mach ines

5 . 5 .9 S o lven t s cou t ing mach ines

W ool s cour ing mach ines

5 .6 .1 Raw woo l s cou t ing mach ines

5 . 6 .2 W ool hank scour ing mach ines

5 . 6. 3 W ool f ab r ic s cou t ing mach ines

5 . 6 .4 Carbon i s ing range fo r woo l l en f ab r ic

5 .6 .5 Crabb ing and deca t i si ng mach ines

5 .7 S i lk d e g u m m i n g m a c h i n e s

5 .7 .1 Yarn degu m m ing mach ines5 . 7 .2 P i ece goods degu m ming mach ines

Refe rences

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132132

132

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135

135

135

136137

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139139

140

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156156

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xii Contents

Chapter 6

6.16.2

6.3

6.4

6.5

6.6

6.7

6.8

160

160161

161

162

B l e a c h i n g o f t e x ti le s

IntroductionBleaching with hypochlori tes

6.2 .1 Calc ium hypochlor i te (b leaching powder)

6.2.2 Sod ium hypo chlori te

6.2.3 Lithium hypo chlori te and chlorinated trisodium

phosphate

6.2.4 Factors effect ing hypo chlori te bleaching operat ions

6.2.5 Acce lerated hypo chlori te bleaching

6.2.6 Adv antages of hypo chlori te bleaching over bleach ingpowder 167

6.2.7 Disadvan tages of sodium hypoc hlori te bleaching over

bleaching pow der 168

Bleac hing with peroxides 168

6.3 .1 M echanism of peroxide b leaching 170

6.3.2 Stabil isers for peroxide bleaching 170

6.3.3 Param eters in peroxide bleaching operat ions 172

Bleaching of wool wi th hydrogen peroxide 1736.4.1 In alkal ine hydro gen peroxide 174

6.4.2 In acidic hydrog en peroxide 174

6.4.3 Alkal ine peroxide fol lowed by hydrosulphite t reatme nt 175

6.4.4 M ordanting and peroxide bleaching 175

6.4.5 Sequen tial oxidat ive and reductive bleaching 176

6.4.6 In em ulsion of hydro gen peroxide 178

Bleac hing of si lk with hydro gen peroxide 178

Bleac hing of synthet ic fibres with peroxide 180

6.6 .1 Regenera ted ce l lu lose 180

6.6.2 Ac etate fibres 180

6.6.3 Ac rylic fibres 180

Advantages and d isadvantages of peroxide over hypochlor i te

bleaching 181

Bleac hing with sodium chlori te 182

6.8 .1 M echanism of b leaching 1826.8.2 Bleac hing of cot ton 183

6.8.3 Bleach ing of polyes ter 184

6.8.4 Bleach ing of nylon 184

163

164

166



Contents xiii

6.9

6.10

6.11

6.12

6.13

6.14

6.15

6.16

6.8.5

6.8.66.8.7

6.8.8

6.8.9

Bleac hing of aceta te f ibres

Bleaching of polyacryloni t r i l eB leach ing o f po lyv iny l a l coho l

Problem of corros ion and i t s prevent ion

Me ri t s and deme ri ts o f ch lor i te b leaching

Bleaching wi th peracet ic ac id

6.9 .1 Cot ton

6 . 9 . 2 Ny lon

6.9.3 Cel lu lose aceta te

6.9 .4 Acryl ics6.9 .5 Me ri t s and dem eri t s

Reduc t ive b l each ing o f woo l

6.10.1 Sulph ur d ioxide

6.10.2 Sod ium bisu lphi te

6 . 10 . 3 S od ium hydrosu lph it e

6 . 10 .4 Th io -u rea b l each ing o f woo l

6 . 10 . 5 Pho to -b l each ing o f woo l

Bleaching of s i lk wi th reducing agents

Reduc t ive b l each ing o f ny lon

Peroxygen b l each ing compounds

Bleach ing o f j u t e

6.14 .1 Hypochlor i te

6 . 14 .2 Hyd rogen pe rox ide

6.14 .3 Sod ium chlor i te

6 .14 .4 Peracet ic ac id

6 .14 . 5 Draw backs i n b l each ing o f j u t e

6 . 14 .6 Causes o f ye l l owing and imp rovem en t o f pho tos t ab il it y

o f b l eached j u t e

B leach ing o f l inen

Bleach ing o f b l ended fab r ics

6.16.1 Polyes ter /co t ton

6.16.2 Polyes ter /wool

6.16.3 Nylon/cel lu lose6 . 16 . 4 Ny lon / woo l

6.16.5 Acryl ic /ce l lu lose

6 . 16 . 6 Acry l i c / woo l

185

185186

186

187

188

190

190

191

191191

192

192

193

193

194

194

194

195

196

196

197

197

198

198

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199

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206207

207

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xiv Contents

6 .16.7 Aceta te /ce l lu lose

6.16.8 Polyes ter / l inen6 . 16 . 9 W ool / v i s cose

6.16.10 Viscose/cot ton

6.17 Blea ching of co t ton we f t kni t ted fabr ics

Refe rences

208

208

209

209

209

211

Chapter 7

7.1

7.27.3

7.4

7.5

Bleaching and washing equipm ent

In t roduct ion

Batch b l each ing p roces s m ach ine r ie sS em i -con tinuous b l each ing p roces s mach ine r i e s

Con t inuous b l each ing by J -Box sys t ems

Con t inuous op en-wid th b l each ing equ ipmen t

7.5 .1 S team ers wi thou t p la i ted s torage

7 . 5 .2 Con veyer s t eamer wi thou t p re - s teep ing zone

7 .5 .3 Con veyer s t eamer wi th p re - s teep ing zone

7.5 .4 Pressure less or Co m bi-s team ers

7 .5 .5 S ubm erged b l each ing sys tems

7 .6 W a s h i n g e q u i p m e n t

7.6 .1 Ro pe w ashing m achines

7 . 6. 2 Open-w id th wash ing mach ines

Refe rences

217217

217222

224

230

232

232

234

236

238240

241

247

257

Cha pter 8

8.1

8.2

8.3

8.4

8.5

Heat-settingIn t roduct ion

Therm al beh av iour o f syn the ti c f ib res

Stages o f heat -se t t ing

Me thods o f hea t - se t ti ng

8.4 .1 Co ntact m ethod

8 .4 . 2 S t eam -se t ti ng me thod

8.4 .3 Hy dro-se t t ing m ethod

8.4 .4 Hea t -se t t ing us ing ten ter f ram e

8.4 .5 Select ive inf ra- red em i t ters m ethodHea t -se t t ing co ndi t ions for d i f ferent k inds o f fibres

8.5.1 Po lyes ter fabrics

8.5 .2 N ylon fabr ics

259

259

259

260

261

261

261

262

263

266267

267

267



Contents XV

8.6

8.7

8.5.3

8.5.48.5.5

8.5.6

8.5.7

8.5.8

8.7.2

8.7.3

8.7.4

8.7.5

Refe rences

Textur i sed fabr ics

Acry l i c and mo dacry l i c f ab r ic sCa t ion i c dyeab l e po lyes t e r

Tr iaceta te f ibres

Polyvinyl ch lor ide f ibres

Elas tomeric f ibres

Hea t -se t t ing of b lended f ibre fabr ics

8.6.1 Polyester/cot ton

8.6 .2 Polyes ter /wool

8.6 .3 Polyes ter / l inen8.6 .4 Polyes ter / s i lk

8.6.5 Poly viny l ch lor ide/cel lu los ics

Effe ct of heat -se t t ing on proper t ies o f synthet ic f ibres

8.7 .1 S t ructura l chan ges

Dimens ional s tab i l i ty

S t i f fness

Crease r ecovery

Dyeab i l i t y

268

269269

269

270

271

271

271

271

272272

272

272

272

273

275

275

276

277

Chapter9

9.1

9.2

9.3

9.4

9.5

9.6

M e r c e r i z a t i o n

Introduct ion

Cond i ti ons fo r merce r i za t ion

Cha nges i n p ropert ie s o f ce ll u lose on merce r i za t i on

9.3 .1 Sw el l ing and shr inkage

9.3 .2 S t ructura l mo di f ica t ion

9.3 .3 Increased lus t re

9.3 .4 Gain in s t rength

9.3 .5 Increased m ois ture absorpt ion

9.3 .6 Increased dye absorpt ion

9.3 .7 Increased react iv i ty

9 .3 . 8 Rem ova l o f imm atu re co t ton

9 . 3 .9 Phys i ca l com pac tnes sMe rce r i za t ion o f r emie and f l ax f ib res

Me rce r i za ti on o f b l ended f i b re f ab r ics

Merce r i z ing mach ine r i e s

279

279

279

288

281

285

286

288

288

289

290

290

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xvi Contents

9 .6 .1 Cloth (wove n) m ercer iz ing m achines

9 .6 .2 Yarn m erce r i z ing mach ines9 .6 .3 Kn i t goods me rce r i z ing mach ines

9.7 Hot me rcer iza t ion

9 .8 L iqu id am m onia merce r i za t ion

Refe rences

293

302303

306

309

315

Chapter 1 0

10.1

10.210.3

10.4

O p t i c a l b r i g h t e n i n g a g e n t s

In t roduct ion

Ch em ical cons t i tu t ion of opt ica l br ightenersM echan i sm o f f l uo rescen t wh i t en ing

Factors inf luen cing the funct ions of opt ica l whi teners

10.4 .1 Subs t ra te

10.4.2 Saturat ion

10.4 .3 M ethod of appl ica t ion

10.4 .4 Time

10.4 .5 Temperature

10.4.6 pH

10.4.7 Salt

1 0 . 5 App l i ca t ion o f op t ica l b r i gh tener s

10.5 .1 Cel lu lose fabr ics

10.5.2 W ool len fabr ics

10.5.3 Si lk fabrics

10.5 .4 Polyes ter

10.5.5 Nylon

10.5.6 Polyacryloni t r i le

10.5 .7 Cat ionic dyea ble polyes ter

10.5 .8 Polyv inyl ch lor ide

10.5 .9 Other synthetic polym ers and p las tics

10.5 .10 B lended f ibre fabr ics

Refe rences

3211

320

321323

323

324

324

324

324

324

325

325

325

326

327

328

328

329

330

331

332

332

332

334

Chapter 1111.1

11.2

11.3

C o m b i n e d p r e - t r e a t m e n t p r o c e s s e s o f te x ti le sIntroduction

Com bined scouring and desizing

Com bined scouring and bleaching

336336

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Contents xvii

11 .4 Com bined des i zing , s cou t ing and b l each ing

Refe rences

339

342

C h a p t e r 1 2 D e g r a d a t i o n o f f ib r e s a s s o c ia t e d w i th c h e m i c a l

p r e - t r e a t m e n t p r o c e s s e s

12 . 1 In t roduc t ion

12.2 Deg radat ion of co t ton dur ing des iz ing

12.3 Deg radat ion of co t ton dur ing scour ing

12.4 Deg radat ion of co t ton dur ing b leaching

12.4 .1 Hyp och lor i te b leaching and dam age12 .4 .2 Perox ide b l each ing and dama ge

12.5 Dam age o f woo l du r ing p re - tr ea tmen t p roces ses

12.6 Da m age of s i lk dur ing pre- t rea tment processes

12.7 Da m age of polyes ter dur ing pre- t rea tment processes

Refe rences

344

344

344

346

350

350353

354

356

357

357

Chapter 13

13.1

13.2

13.3

13.4

13.5

C o n s e r v a t io n o f e n e r g y a n d w a t e r , e c o n o m y a n d

e f f lu e n t c o n t r o l i n p r e - t r e a t m e n t p r o c e s s e sWater consumpt ion in tex t i l e indus t ry

Impuri t i es in water

Water pur i f ica t ion

13.3 .1 Sod a-alum process

1 3 . 3 . 2 L i m e - s o d a p r o c e s s

13.3 .3 Base exch ange process

Economy th rough energy conse rva t i on

13.4 .1 Eff ic ient generat ion of energy and m inim um

consumpt ion

13 .4 .2 Mech an ica l remo va l o f wa t e r be fo re d ry ing

13.4 .3 Increased ef f ic iency of dry ing and heat -se t t ing

13.4 .4 Re duce d liquor to ma ter ia l ra t io

13.4.5 Eff ic ient heat recove ry

13.4 .6 Hea t recove ry f rom process ef f luents

Economy th rough wa te r conse rva t i on13.5.1 M inim ising l iquor to m aterial rat io

13.5 .2 M inimis ing wash l iquor

13.5 .3 Re -us ing r ins ing bath wa ter

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361

363

363

363

364

364

365

365

365

366

366

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xviii Contents

13.5.4 Direct steam injection

13.6 Economy through process modification13.6.1 Vaporloc bleaching

13.6.2 J-Box bleaching

13.6.3 Solvent scouting

13.6.4 Cold bleaching

13.6.5 Combined processing

13.6.6 Shortening of process sequence

13 .7 Pollution aspects in pre-treatment processes of textiles

13.7.1 Water and air pollution13.7.2 Parameters for assessment of harmful materials in

waste water

13 .8 Pollution load and pre-treatment processes

13.8.1 Desizing effluents

13.8.2 Scouting effluents

13.8.3 Bleaching effluents

13.8.4 Auxiliary effluents

13 .9 Waste water treatment from pre-treatment plants

13.10 Protective measures for ultra-violet radiation

References

368

368368

368

368

369

369

369

370

370

372

374

376

377

378

379

380

390

391

Chapter 14

14.1

14.2

P r e - t r e a t m e n t o f t ex ti le s u n d e r p l a s m a c o n d i t io n s

Introduction

The concept of plasma

14.2.1 Corona discharge

14.2.2 Glow-discharge

14 .3 Generation of plasma and its action

14.3.1 Machine performance for producing plasma

14.3.2 The interaction of plasma with substrate

14.4 Surface modification of fabrics under plasma treatment

14.4.1 Plasma treatment of wool

14.4.2 Plasma treatment of other fabrics

14 .5 High energy radiation of textilesReferences

3 9 5

395

395

396

396

397

398

404

407

407

410

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Contents xix

Chap ter 15 A p p l i c a t i o n o f b i o - t e c h n o l o g y i n t h e p r e - t r e a t m e n t

pr o ce s s e s o f t e x t i l e s

15.1 Introduction

15.2 Enzymes for textile application

15.2.1 The chemistry of enzymes

15.2.2 Mechanism of enzyme action on cotton

15.2.3 Parameters governing the cellulase treatments

15.2.4 Structural and morphological changes of fibres by

enzymatic hydrolysis

15.2.5 The use and advantages of enzymatic processing15.3 Treatment of cotton with enzymes

15.3.1 Enzymatic desizing of cotton and silk

15.3.2 Use of enzymes in mercerization

15.3.3 Enzymatic scouting and bleaching processes

15.3.4 Bio-polishing

15.3.5 Effect of cellulase treatment in washing processes

15.3.6 Stone washing

15.4 Treatment of protein fibres with enzyme15.4.1 Wool carbonising

15.4.2 Wool bleaching

15.4.3 Shrink-proofing and modification of wool

15 .5 Bio-technology and effluent treatment

References

41~418

418

418

420

422

423

424425

426

426

426

428

431

431

432433

433

434

435

436

Chapter 1 6

16.1

16.2

16.3

A n a l y s i s a n d t e s t i n g i n p r e p a r a t o r y p r o c e s s e s

Introduction

Analysis of water

16.2.1 Suspended matter

16.2.2 Total soluble salts

16.2.3 Total hardness

16.2.4 Calcium hardness

16.2.5 Magnesium hardness

16.2.6 Temporary and permanent hardnessAnalysis of non-cellulosic residues

16.3.1 Ash content (mineral matter)

16.3.2 Silicate and phosphate

441

441

441

442

442

442

443

443

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xx Contents

16.4

16.5

16.6

16.7

16.8

16.9

16.10

16.11

16.3.3 Calcium and magnesium

16.3.4 Iron and copper

Evaluation of wax content in cotton

Evaluation of lubricants

16.5.1 Total fatty matter

16.5.2 Saponification value of an oil

16.5.3 Unsaponification matter

Determination of moisture content

Tests and analyses of sizes

16.7.1 Identification of sizes16.7.2 Percentage size by ordinary method

16.7.3 Total size by Soxhlet method

16.7.4 Total size by enzyme method

Determination of the efficiency of scouting

16.8.1 Measurement of weight loss

16.8.2 Measurement of residual wax content

16.8.3 Practical test of absorbancy

16.8.4 Removal of motes (kitties)Testing and evaluation of bleaching agents

16.9.1 Bleaching powder

16.9.2 Sodium hypochlorite

16.9.3 Sodium chlorite

16.9.4 Hydrogen peroxide

16.9.5 Stabilisers for peroxide bleach

16.9.6 Sodium hydrosulphite

16.9.7 Sodium bisulphite

16.9.8 Sodium silicate

Assessment of damage of cellulose

16.10.1 Determination of fluidity

16.10.2 Determination of Copper Number

16.10.3 Methylene Blue absorption test

16.10.4 Silver nitrate test

16.10.5 Determination of acidic groups by iodometric methodAssessment of damage of wool

16.11.1 Microscopic test

16.11.2 Swelling test

444

445

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448

449451

451

451

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452

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Contents xxi

16.11.3 Solubi l i ty te s t

16 .11 .4 S pe c t r oph o tom e t r i c t e s t

16 .12 De te r m ina t ion o f de g r e e o f m e r c e r i z a t ion

16 .12 .1 De c onvo lu t ion c oun t

16 .12 .2 S w e l l ing inde x

16 .12 .3 B e nz opur pur ine t e s t

16 .12 .4 S od ium hydr ox ide spo t t ing te s t

16 .12 .5 Goldthwai t r ed-green te s t

16 .12 .6 S ta in ing te s t

16 .12 .7 B a r ium a c t iv i ty num be r16 .12 .8 Dete rmina t ion of lus t re

16 .12 .9 X-ray ana lys is

16 .12 .10 Inf ra - red ana lys is

16 .13 Eva lua t ion o f wh i t e n ing e f fi c i e nc y o f op t i ca l b r igh te ne r s

16 .13 .1 Visua l a ssessment

16 .13 .2 Ex t r a c t ion m e thod

16 .13 .3 Ins t rumenta l ana lys is

16 .14 De te r m ina t ion o f de g r e e o f he a t - se t ti ng16 .14 .1 Shr inkage te s t

16 .14 .2 C r e a se r e c ove r y a ng le

16 .14 .3 Asse s sm e n t o f ha nd le

16 .14 .4 I od ine a bso r p t ion m e thod

16 .15 De te r m ina t ion o f b iode gr a da b i l i t y o f su r fa c t a n ts

16 .15 .1 M e thy le ne B lue m e thod

R e f e r e nc e s

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Chapter 1

K I N D S O F F I B R E S

1.1 I n t r o d u c t i o nT e x t i l e f ib e r s c o n s i st o f p o l y m e r s . P o l y m e r s a re l o n g c h a in m o l e c u l e s w h i c h

a r e fo r m e d b y c h e m i c a l l y j o i n i n g t h e m o n o m e r s a n d t h e p r o c e s s i s k n o w n a s

p o l y m e r i s a ti o n . T h e l e n g t h o f t h e c h a in i s r e p r es e n t e d b y d e g r e e o f p o l y m e r i s a t i o n

( DP). I f a po lym e r i s f o r m e d f r om two o r m or e m ono m e r s , i t i s c a l l e d c opo lym e r .

To im pr ov e the p r ope r t i e s o f t he fib re som e t im e s a dd i t iona l m o no m e r i s g ra f t e d on

to the po lym e r c ha in .

W i th the in t r oduc t ion o f ne w f ib re s du r ing the la s t de c a de a n d inc r e a s ing c on-

sum pt ion o f f ib r e b l e nds i t ha s be c o m e ne c e ss a r y to look a t ge ne r a l f ib re c he m is t r y

a s the p r e - t r e a tm e n t t e c hn o log y o f one fib r e is d i ff e r e n t to tha t o f a no the r. Ta b le

1 .1 g ive s som e o f the g loba l t e x t il e fib r e c on sum pt ion da ta . The c on sum pt ion o f

T A B L E 1 . 1

G l o b a l F ib r e D e m a n d

( Uni t : 10 0 0 tons : sha r e % in c ons um pt ion)

F i b e r T y p e 1 9 9 4 2 0 0 0 A n n u a l G r o w t h ( % )

Co t ton 15160 (41 .3) 16530 (31 .2) 1 .5W ool 1520 (4 .1) 1720 (4 .1) 2 .1

Ce l lu lo s ic 232 0 (6 .3) 2280 (5 .4) -0 .3

Syn the t ic 17720 (48 .2) 216 40 (51 .3) 3 .4

S ou r c e : The Ja pa ne se M in i s t r y o f I n t e r na t iona l T r a de & I ndus t r y .

c e l lu los ic f ib re s i s e xpe c te d to de c l ine m a r g ina l ly a t t he ra t e o f 0 .3%. The in t e r p la y

be tw e e n f ib r e s t ruc tu r e , m or ph o log y a nd c he m ic a l c om pos i t ion i s a n e s se n t ia l pa r t

o f a ll p r e - t r e a tm e n t p r o c e sse s a nd thus , i t i s ne c e s sa r y to kno w the d i f f e r e nc e s in

the s t r uc tu r e s o f d i f fe r e n t po lym e r s a nd the i r e f f e c ts on the p r op e r t i e s o f t he f ib re s .

T h e r e a r e m a n y g o o d b o o k s o n t h i s s u b j e c t an d h e n c e o n l y g e n e r a l f i b re c h e m i s t ry

a n d m a n u f a c t u r i n g p r o c e s s e s a r e p re s e n t e d i n r e fe r e n c e f o r m a n d t h e n p r o c e e d e d

to d i sc uss ho w p r e p a r a to r y p r o c e sse s a r e c hose n f o r u se a s fib r e p r oc e ss ing .

1 .2 C l a s s i f i c a t i o n o f F i b r e s

Though t e x t i l e f ib r e s a r e c l a s s i f i e d by m a ny sys t e m s , i t i s on ly in 19 6 0 , the

Te x t i l e F ib r e P r oduc t s I de n t i f i c a tion Ac t ( TFPI A) be c a m e e f f ec t ive . Th e c la s s i f i-

c a t ion sho w n in Ta b le 1 .2 i s ba se d on the p r inc ipa l o r ig in o f the f ib re ( na tu r a l o r



2 Kinds of Fibres

TABLE 1 .2

Clas sif icat ion of Texti le Fibres [ 1

Fibre9 I Il

Na tural Cellulosic Natural Protein Fibres

Fibres 1. a n i m a l h a i r f ib r e s :

1. s e e d h a i r s : (a) wo ol (sheep) (b) spe-

(a) cotto n (b) m ilk cialty hair f ibres like al-

we ed (c) kapo k paca , Cam el , Cashmere ,

(d) cat ta il guanaco , l lama, mo hair

(angora go at), vicuna (c)

f u r f i b r e s l i k e m i n k ,mu skrat , ango ra, rabbit .

2. b a s t f i b r e s :( a) f lax (b) rem ie

(c) hem p (d) ju te

(e) sunn (f) ke na f

(g) urena

3. leaf f ibres :

(a) abaca

(b) pineapple

( c ) a g a v e ( s i s a l ,henequen) (d) pa lm

IR e g e n e r a t e d N a t u r a l

Fibres

1 . r a y o n :

( a ) C u p r a m m o n i u m

Bemberg (b) Viscose

rayon l ike regu lar &high tenacity , h igh wet

m o d u l u s , h o l l o wfibires.

Synthletic

Fibres

2 . a n i m a l s e c r e t i o n 9

(a) silk fibre like culti-

va ted , dup ion i , tussah ,

wild (b) spider silk.

2 . a c e t a t e :

(a) secondary acetate

(b) tri-acetate.

3 . p r o t e i n "

(a) casein (b) zein (c)

peanu t (d) soyabean.

4 . M i s c e l l a n e o u s 9

( e ) N ew Z e l an d (a ) a lg ina te ( b )r u b b e r.

flax (f) yu cc a I I ! I1 . c o n ~ e n s a - 2 . a d d i t i o n 3 . e la st0 m er s' 4.m a nm ad e 5 . o t h e r 9(g) palm a ist let io n p o l y m e r p o l y m e r : ( a) S p an d ex m i n e r a l : ( a ) a l g i n a t e

f i b r e s : (a) anid ex (b) (b) rub ber (a) glass (b) inorga nic4 . f r u i t "co ir (a) nylon 6, 6, ac ryl ics (c) (c) lastrile . (b) metallic, like Avce ram ,

nylon 6, mod acrylic Fibrefax,

5 . m in era l 9 ny lon type (d) novolo id Tho me l (c)asb esto s 11, 6, 10, (e) nytr il (f) Org ani c like

aromatic olef in f ibres PBI, Tef lon

ty pe lik e po ly et h- (d) biconstiment.

(Quina), ylene,

b icomponent po lypropy-

ny lon (b) lene (g) Saran

aram id like (h) Vinal

Kevlar and ( i) Vinyon.

nomex (c)Polyester.



K i n d s o f F i b r es 3

m a n- m a de ) , c he m ic a l t ype ( c e l lu los i c , m a n- m a de c e l lu los i c ) , ge ne r i c t e r m ( se e d ,

h a ir , r a y o n ) a n d c o m m o n n a m e s a n d t ra d e n a m e s o f t h e fi b re s ( c o tt o n , v is c o s e ,r a yon) . Ho w e ve r , t h i s li s t o f fib r e s und e r suc h c a t e gor y is no t c om ple te a nd f o r

c om ple te l i st boo ks a r e to be r e f e r r e d [2 ,3 ] .

1 .3 C h e m i c a l C o m p o s i t i o n , M o r p h o l o g y a n d S t r u c t ur e o f C o t t o n

T h e a p p a r e l i n d u s t r y i s p r e - d o m i n a n t l y c o t t o n b a s e d a n d t h e s h a r e o f c o t to n i n

t o ta l fi b re c o n s u m p t i o n i s a b o u t 7 0 -7 5 % . T h e c o t t o n p r o d u c t i v i t y o f m a j o r c o u n -

t r ie s i s dep ic ted in Table 1 .3 .

T A B L E 1 . 3

C o t ton P r oduc t iv i ty 19 9 2- ' 9 3

C o u n t r y K g / H e c t a r e s

I nd ia 30 4

B r a z i l 38 4

Pa k i s t a n 550

C hina 6 6 0

U S A 7 2 8

C I S ( F o r m e r l y U S S R ) 7 2 8Israel 1830

S our c e : I nd ia n Te x t i l e C om m iss ion e r S ta t is t ic s .

C o t ton i s s ing le c e ll f ib r e a nd de ve lop s f r om the e p ide r m is o f the se e d [4 ]. An

e long a t ion pe r iod c on t inue s fo r 17- 25 da ys a ft e r f lowe r ing . C o t ton c ons i s t s o f

c e l lu los i c a nd non - c e l lu los i c m a te r i a l . A m or ph o log ic a l s t r uc tu r e o f the c o t ton

f ibre is g iven in Fig . 1-1 . Th e ou te r m os t layer of the cot ton f ibre i s the cut ic le ,

c ov e r e d by w a xe s a nd pe c t in s , a nd th i s su r r ounds a 'p r im a r y wa l l ', bu i l t o f c e l lu -

F igu r e 1 - 1 . C o nc e p t o f a n ide a l i z e d c o t ton f ib r e [5 ] .

l o se, pe c t in s , wa x e s a nd p r o te in i c m a te r i a l [6 ]. The inne r pa r t o f t he c o t ton f ib r e



4 Kinds o f F ib r e s

c om pr i se s the ' s e c onda r y w a l l' , subd iv ide d in to se ve r a l l a ye r s o f pa r a l le l c e l lu lose

f ibr i ls , and the lumen. The sm al les t uni t of the f ibr i l s i s the e lem enta ry f ibr i l,c ons i s t ing o f de nse ly pa c ke d bu nd le s o f c e l lu lose c ha ins [7] , f o r wh ic h h igh ly o r -

de r e d ( c r ys t a l l i ne ) r e g ions a l t e r na te w i th l e s s o r de r e d ( a m or phous ) r e g ions in a

longi tu dina l d i rec t ion . Ins ide the m ic rof ibr i l s a m ic rocapi l la ry sy s tem is deve loped

[8] . The se two c a p i l l a ry sys t e m s a r e r e spons ib le f o r swe l l ing a nd a bso r p t ion p r o -

c e s se s wh ic h a r e im p or t a n t f o r t he p r e - t r e a tm e n t o f c o t ton [9 ]. The p r im a r y a nd

se c ond a r y w a l l c e llu lose r e su l t f r om d i f f e r e n t po lym e r i sa t ion m e c ha n i sm s [ 10] .

C o t ton c ons i s t s o f p r a c t i c a l ly pu r e c e llu lose a nd m a y be c h e m ic a l ly de sc r ibe d

as po ly (1 , 4-B -D- anhy drog luco py rano se) (Fig . 1-2). The he l ica l r eversa l s t ruc -

, C H 2 O H , -, O H - '" O "

Figu re 1-2 . M olec ula r s t ruc ture and con f igura t ion of ce l lu lose [ 11].

tu r e o f na tu r a l c e l lu lose shows the c ons ta n t ly r e c u r r ing c e l lob iose un i t , c ons i s t ing

of two g luc ose un i t s e a c h wi th s ix c a r bon a tom s . The l e ng th o f un i t c el l a long the

f ibre axis i s 10 .4A ca lcula ted for the ce l lobiose uni t . In na tura l ce l lu los ic f ibres

the re a re 3 000 - 5000 C 6 or g lucose u ni ts jo in ed tog e ther . This c or respo nds to a

m o le c u la r we igh t o f t he o r de r o f 30 0 ,0 00 - 50 0 ,0 0 0 .

When cot ton f ibres dry f rom the i r in i t ia l fu l ly swol len s ta te , the ce l l wa l l co l -

lapse to g ive a typica l k idney-shaped (Fig . 1-3) c ross- sec t ions and the d i f fe rent

" ~ c u t i d e[ 1 2 L - - - - , o o ~

i t~-'-----pr imary w a l l

Figu re 1-3 . Dia gra m o f a co t ton f ibre , c ross- sec t ion .

r e g ions o f the c r os s - se c tion ha ve im po r t a n t d i ff e r e nc e s in st r uc tu r e [12 ]. Th i s i s

co m m on ly re fe r red to as 'b i la te ra l s t ruc ture ' o f the cot ton fibre . Th e f ibre i s mo re



K i n d s o f F i b r es 5

a c c e ss ib l e to l i qu ids on the c onc a v e s ide o f the f ib r e , wh ic h c ou ld l e a d to une v e n

pe ne t r a t ion . The sp i r a l a r r a ng e m e n t o f m ic r o f ib r i l s r e ve r se s d i r e c t ion on r o t a t ionpe r iod ic a l ly a long the le ng th o f the fib r e [ 13 ,14 ] . Ac c o r d ing ly , som e r e la t ionsh ip

be tw e e n c onv o lu t ion a n g le a nd f ib r e s t r e ng th is e s t a b l i she d [15 ].

I n t h e c r y s t a l l i n e p a r t , t h e c e l l o b i o s e u n i t s a r e c l o s e l y p a c k e d t o f o r m

C e l lu lose I in na t ive c e l lu lose f ib re s a nd C e l lu lose I I i n re ge n e r a t e d c e l lu lose f i -

b r e s . I n C e l lu lose I the c ha in m ole c u le s a r e pa r a l le l t o one a no the r [ 16 ] . The f o lde d

c ha in o c c u r s a t C e l lu lose I I, i n the c r ys t a l l ine r e g ions the c ha in m ole c u le s a r e a n t i-

pa r a l le l . Thus , t he ba s i s f o r he l i c a l s t r uc tu r e f o r C e l lu lose I is p r e f e r a b ly e x te nd e d

to the s t ru c ture of C e l lu los e I I [ 17 ].

1 . 3 . 1 Cot ton im pur i t i e s

The im p ur i t i e s in c o t ton f ib re c a n r a nge f r om 4 to 12% ( o .w . f . ) a nd the ove r a l l

c om pos i t ion o f c o t ton f ib re s a re ind ic a t e d in Ta b le 1 .4 . Eve n a f t e r m e c ha n ic a l

T A B L E 1 . 4

C o m p o s i t i o n o f M a t u r e C o t t o n F ib r e s

C ons t i tue n t s P e r c e n t a g e b y d r y w e i g h t

a - c e l l u l o s e 8 8 . 0 - 9 6.5

P r o te i n 1 . 0 - 1 .9

W a x 0 . 4 - 1.2

Ash ( inorganic sa l t s )

Pe c t in s

Othe r s ( r e s ins , p igm e n t s ,

he m i - c e l lu lose , suga r s ,o r ga n ic a c ids , i nc r us t e d

l igne ous subs ta nc e )

0 . 7 - 1 . 6

0 . 4 - 1 . 2

0.5 - 8.0

g i n n i n g p r o c e s s , c e r t a in a m o u n t o f s e e d - c o a t f ra g m e n t s , a b o r t e d s e e d s a n d l e a v e s

e tc. , c l inge ( a dh e r e ) to the f ib r e a nd the se im p ur i t i e s a re c a l l e d 'm o te s '. The im pu -

r i t ie s in co t to n f ibre va ry acco rdin g to the f ibre m atur i ty [18] (Table 1 .5) . Co t ton

im p ur i t i e s a r e loc a te d l a r ge ly on the ou te r s ide o f the f ib r e ( Ta b le 1 .6 ). The no n-

c e l lu los i c m a te r i a l i s m a in ly s i tua t e d in the p r im a r y w a l l a nd the se c o nda r y wa l l i sm a in ly c o m po se d o f c e l lu lose . The i r qua n t i ty i s h ighe r w he n the f ib re i s f ine r , t ha t



6 K i nds o f F i b re s

T A B L E 1 . 5 .

I n f l ue nc e o f Ma t u r i t y on the I mpu r i t i e s o f C o t t on F i b re s( in pe rc e n t o f d ry w e i g h t ) [ 19]

C ons t i t ue n t s U. S . Cot ton

M a t u r e I m m a t u r e

W axes 0 .45 1 .14

Pro teins 1.01 2.02

As h 0 .71 1.32

Pect in s 0 .58 1.26

TA B L E 1 . 6 .

P rop or t i on o f C e l l u l os i c a nd N o n-c e l l u l os i c Ma t e r i a l i n

W h o l e o f C o t to n F i b re a n d i n P r i m a r y W a l l [ 2 0]

C ons t i t ue n t s P ropor t i on ( w t . % )

O f t he w ho l e f i b re O f p r im a r y w a l l

Ce l lu lose 88 - 96 52

Pe c t i n s 0 . 7 - 1 .2 12

W a x e s 0 . 4 - 1 .0 7

Pro tein s 1.1 - 1.9 12

M iner als 0 .7 - 1.6 3

O t he r o rga n i c c om pou nds 0 .5 - 1 .0 14

i s to say wh en the spe c i f i c sur fac e a rea i s l a rge [21 ] . Othe r fac tors wh ich inf lu encet he i mpu r i t i e s i n r a w c o t t on a r e 9 e o l og y o f t he c u l t iva t i on a r e a , s o il c ons t i tu t i on ,

w e a t he r c ond i t i ons du r i ng t he ma t u r i ng pe r i od , c u l t i va t i on t e c hn i que , r a w c o t t on

t r e a t me n t e tc .

The p ro t e i ns a r e s i t ua te d i n t he c e n t r a l c a v i t y o f t he f ib r e a nd a r e t he r e fo re r e l a -

t i ve l y i na c c e s s i b l e t o c he mi c a l a t t a c k . A bou t 14% ( on d ry w e i gh t ) p ro t e i ns a r e

c on c e n t r a t e d i n t he p r i m a ry w a l l o f t he c o t ton f ib r e , bu t t he i r p r e s e nc e i n t he l ume n

a re a l s o r e po r t e d [ 22 ]. The e l e me n t s o f p ro t e i n c om pon e n t s g e ne ra l l y found t o be

a re : l e uc i ne , va l i ne , p ro l i ne , a l a n i ne , oxyp ro t e i ne , t h r e on i ne , g l u t a mi c a c i d , g l y -

c ine , s e r ine , a sper t i c ac id , a spergine , lys ine and a rg in ine [23] . The ye l lowish or



K i nds o f F i b re s 7

b ro w n d i s c o l ou ra t i on o f t he c o t ton f i b r e is r e l a t e d to t he p ro t o p l a s m i c r e s i due s o f

p ro t e i n [ 24 , 25 ] a nd t he f la vone p i g m e n t s o f c o t t on f l ow e r s [ 26] .

N a t u ra l o i l s a nd w a xe s a r e m os t l y m i x t u re s o f f a t ty a l c oho l s , f a t ty a c i ds a nd

e s t e r s o f t he s e c a rboh ydra t e s [ 27] . W a x c on t e n t va r i e s g r e a t ly a mo ng t he d i f f e re n t

va r i e t i e s o f c o t t on a nd a l s o s a me va r i e t y g row n i n d i f f e r e n t loc a t i ons . The w a x i s

l oc a t e d o n t he ou t s i de o f t he c o t t on f i b r e a nd t he qua n t i t y i nc r e a s e s w i t h s u r f a c e

a r e a o f c o t to n [ 2 8] . T h e c o m p o s i t i o n a n d r e m o v a l p r o p e r ti e s o f c o t to n w a x a r e

g i ve n in Ta b l e 1 . 7. C o t t on w a x c on t a i n c a rbon ( 8 0. 38 % ) , hy dro ge n ( 14 . 51% ) a nd

T A B L E 1 . 7

C o m p o s i t i o n o f R e m o v a l P r o p e r t ie s o f C o t t o n W a x [ 27 ]

C o m p o n e n t C o n t e n t ( % )

W a x e s te r 2 2

Phy t os t e ro l s 12 . 14

Po l y t e rpe n e s 1 - 4

H y d r o c a r b o n s 7 - 8

Fre e W a x a l c oho l s 42 - 46

S a p o n if ia b le 3 6 - 5 0

N o n- s a po n i f i a b l e 50 - 6 3

I n er t 0 - 3

o x y g e n ( 5 . 1 1 % ) [ 3 0] . T h e l i n k a g e b e t w e e n c e l l u lo s e a n d w a x e s a r e m a i n l y d u e to

pho s pha t i de s [ 31 ] a nd a mi no a c i ds , g l uc o s e a nd w a x a c i ds [ 32] . M e l t i ng po i n t s o f

c o t t on w a xe s va ry be t w e e n 6 8 t o 8 0 ~

The i no rga n i c m a t t e r s ( r e s idua l a s h ) i n c o t t on c on t a i n c a t i on ( K § N a § C a 2§

M ga+,Fe 2§ Fe 3+, AP +, M n 2+, Cu2+and o ther s ) and anion s (CI-, CO 3, PO43",8042p l us

Fe , M g , C a a s in s o l ub l e p e c t i na t e s ) [ 19] . The a l ka l i ne e a r t h e l e m e n t s v a ry f rom

f i b re va r i e t i e s a nd r e qu i r e a pp ropr i a t e t r e a t me n t s t o r e duc e t he i r p r e s e nc e on t he

f i b re a s f a r a s pos s i b l e . A ny r e s i due p r e s e n t i n t he f ib r e w i ll l e a d t o the fo rm a t i on

of in s o l ub l e a l ka l i ne e a r t h c a rbona t e s o r hydrox i de s d u r i ng a l ka li ne s c our i ng . The s e

s a l t s c ha nge t he s o f t w a t e r t o ha rd w a t e r r e nde r i ng c e r t a i n dye s i n s o l ub l e w h i c h

m ay b e a t t ac hed to the f ibe r sur face [3 3] .

Pe c t i n i s t he na m e a pp l i e d t o i mp ure m e t hy l pe c t a t e . Pe c t i n s ( 0 . 4 - 1 . 2% ) a re



8 Kin d s o f F ib r e s

p r e s en t i n co t t o n a s a p o ly - D - g a l ac tu r o n i c ac id i n t h e f o r m o f in s o lu b l e s a l ts o f

Ca , M g an d F e [3 4 , 3 5 ] .C h e m i c a l l y h e m i c e l l u lo s e s a re a ra b a n e , x y le n e , g a l a c ta n e , m a n n a n ,

g a l a c t o m a n n a n , a r a b i n o m a n n a n , a s w e l l as m o n o s a c c h a r i d e s , d i s a c c h a r i d e s a n d

d ig o s a cch a r id es . Hem ice l l u lo s es a r e ea s i l y s o lu b l e i n a lk a li an d h y d r o ly s ed b y

ac id s . O th e r s u b s t an ces a r e r ed u c in g s u g a r s s u ch as h ex o s es , p en to s es , f r ee g lu -

co s e e t c ., co n s t i tu t e t h e b as e u n it s o f h em ice l l u lo s e . C i t r ic an d m a l i c ac id , en -

c r u s t ed l i g n eo u s s u b s t an ces a r e co lo u r ed p ig m en t s .

1 .4 N a t u r a l P r o t e i n F i b r e s

N atu r a l p r o t e in f i b r e s a re g en e r a l l y o b t a in ed f r o m an im a l h a i r s an d an im a l s e -

c r e t i o n s . P r o t e in f ib r e s h av e h ig h e r m o i s tu r e r eg a in an d w a r m th n es s t h an n a tu r a l

ce l l u lo s i c f ib r e s . N a tu r a l p r o t e in f ib r e s h av e p o o r r e s is t an ce t o a lk a l ie s b u t h av e

g o o d re s i l i en cy an d e la s t ic r eco v e r y . A g o o d p r ecau t io n i s n ece s s a r y d u r in g t h e

che m ica l p re - t r ea tm ent o f na tu ra l p ro te in f ib res (excep t s i lk ) due to i ts low s t r eng th .

1 .4 .1 M o l e c u l a r s t r u c tu r e o f w o o l f i b r e s

W o o l f i b re g r o w s f ro m th e s k in o f s h eep . I t i s co m p o s ed o f p r o t e in k n o w n as

k e r a t i n . M a jo r v a r i e t ie s o f w o o l co m e f r o m Mer in o , L in co ln , Le i e s te r , Su s s ex ,Ch ev io t an d o th e r b r eed s o f s h eep . D i f f e r en t s p ec i e s o f s h eep p r o d u ce d i f f e r en t

t y p es o f w o o l i n fi b re l en g th , d iam e te r an d o th e r ch a rac t e r is t i c s. T h e m o d i f i ca t i o n

o f th e f ib r e p r o p e r ti e s d u r in g g r o w th b y d i e t a ry ad d i t i v es t o p r o d u ce p u r p o s e - g r o w n

w oo ls i s poss ib le . Ge ne ra l ly f ine wo ol f ib res a re 1 .5 -5" in leng th and 14 - 40~t in

w id th . W o o l f i b re s a r e r o u g h ly o v a l i n c r o s s - s ec t i o n an d g r o w s in a m o r e o r le s s

w av y f o r m w i th a ce r t a in am o u n t o f tw i s t. T h e w av in es s i s ca l l ed c rim p (F ig 1 - 4 ) .

T h e f i n e r t h e w o o l t h e m o r e i s t h e c r im p .

I,| o r x l s I

F ig u r e 1 -4 . D iag r am o f w o o l f ib r e c rim p an d t h r ee - d im en s io n a l

d i ag r a m o f w o o l f ib r e , s h o w in g c r im p .





1 0 Kin d s o f F ib r e s

g l an d i s b e l e iv e d t o p r o d u ce t h e w ax [3 7 - 3 9] , an d t h e s u d o r i f e ro u s g l an d t h e s u in t

[3 7, 3 9 ] . As t h e o p e n in g o f t h e s eb aceo u s g l an d i s p l aced b e lo w th a t o f th e s u d o -r i f e r o u s g l an d , t h e w ax i s d ep o s i t ed d i r ec t l y o n to t h e g r o w in g f i b re w h i l e t h e s u in t

i s d ep o s i t ed o v e r t h e w ax . T h i s i s t h e s i tu a t i o n o f t h e p r im ar y f i b r e s; t h e s eco n d a r y

f ib re s d i f f e r in t h a t t h ey d o n o t u s u a l l y h av e a s u d o r i f e ro u s g l an d .

An im p o r t an t co m p o n e n t o f cu t i c le i s 1 8 - m e th y l - e i co s an o ic ac id [ 4 0 ]. F a t t y

ac id i s b o u n d to a p r o t e in m a t r ix , f o r m in g a l ay e r in th e ep i cu t ic l e [ 4 1 , 4 2 ] , an d t h is

l ay e r i s r e f e r r ed t o a s F - l ay e r [ 4 3 ]. T h e F - l ay e r can b e rem o v ed b y t r ea tm en t w i th

a lcoh ol ic a lka l ine ch lor ine so lu t ion in o rder to enhance w et tab i l ity . The cu t ic le and

ep i cu t i c l e co n t r o l t h e r a te o f d i f f u s io n o f d y es an d o th e r m o lecu l e s o n to t h e f i b re

[4 4 ]. T h e co r t ex , h o w e v e r , co n t r o l s t h e b u lk p r o p e r t i e s o f w o o l an d h as a b i l a t e r a l

s t r u c tu r e co m p o s e d o f tw o ty p es o f ce l ls r e f e r r ed to a s o r th o an d p a r a [ 4 5 , 4 6 ] . T h e

co r t i ca l ce l l s o f b o th a r e en c lo s ed b y m em b r an e s o f at l e a s t t h r ee d i s t in c t l ay e r s

w i th in w h ich t h e m ic r o f ib r i ls f it . Ce l l s o f i n t e r m ed ia t e ap p ea r an c e an d r eac t i v i t y

d es ig n a t ed m es o - co r t ica l h av e a l s o b een r ep o r t ed [4 7] . Co r t i ca l ce ll s o n th e o r th o

s ide are den t i - cu t ic le and th in , those on the para s ide a re po lygonal and th ick [47] .

F ig . 1 -7 i llus t r a tes the b i la te ra l s t ruc tu re w hich i s r espo ns ib le fo r the c r imp of the

F ig u r e 1 -7 . Co m p ar i s o n o f co r t ica l ce l ls (Co u r t e s y o f l ' I n s t it u t T ex t i l e d e F r an ce ) .

f ib r e . T h e tw o ce l l s d i f fe r in ch em ica l co m p o s i t i o n an d d en s i t y an d can b e d i f f e r-



Kind s of F ibres 11

e n t i a t e d unde r the m ic r osc o pe us ing po la r i s e d l igh t a nd a l so by se l e c t ive s t a in ing

te c hn ique s . Th e o r tho c o r t e x a r e c he m ic a l ly m or e r e a c t ive a nd ha ve a g r e a t e r r e -c e p t iv i ty to c e rt a in dye s . I n the c e n t re o f t he woo l i s t he m e du l l a , w h ic h c ons i s t s o f

sp i r a l -sha pe d , a i r -f i l le d c e ll s . The f ine r woo l s , ha v ing no m e d u l l a , a bso r bs dye s

m o r e r a p id ly . M e du l l a c on ta ins p igm e n t tha t g ive s co lou r to f ib r e .

Kera t in i s of amphote r ic in na ture and i s composed of 16 to 18 d i f fe rent oc -

a m ino a c ids . The a m ino a c id r e s idue s jo in toge the r to g ive a po lyp e p t ide c ha in .

The r e a r e two type s o f s tr uc tu r e pos tu l a t e d f o r woo l f ib r e : one i s f o lde d f o r m o f

kerat in ( ot - form ) [Fig. 1-8] and the other is hel ical or spira l s tructure (Fig. 1-9) .

~ ' c o ( ' o " /

"~.C:H--CH,,-S- S ' CH;.--CH

N H ( C y s t in e in k a g e ~NH (~ C O C O . . , . .

R H C , . I ~ CHR. , ~ N H :~ I H~ I '

"-"'"CO,,,~ "" R-(C

t l I 4 ~ F ( NH,, ~- <

NH~~..~A'(;H;Glutamic'cH~'c'OOacid~I~ H , GH~,-CHt-CH1"CHNw,,N~Lysine. ." c o } c o ' (

. ~ C , I " S a l t l in k a g e *,,.eq

NH.,.

:'.4 _ "~ H ~ . N H I

c o c o/ \

R H C C H R

R = a m i n o a c i d o r o t h e r r e a c ti v e g r o u p s

Figur e 1-8 . Folde d cha in charac te r i s t ic

o f a - k e r a t i n ( A f te r A s b u r y ) .

Figure 1-9 . He l ica l or sp i ra l s t ruc ture

o f woo l ( Af te r Pa u l ing a nd C ur e y) .

W he n the f ibre i s s t re tched, the coi l ex ten ds to g ive [3- ke ra t in and on re leas ing the

ke r a t in ba c k in to a - f o r m [48] . The a m ino a c id a nd se que nc e in wo o l va r i es w i th

the va r i e ty o f woo l [49 ] . The a v e r a ge a m ino a c id c on te n t s f o r m a jo r va r ie t i e s o f

wo ol and s i lk a re g iven in Tab le 1 .8 . R represents re la t ive ly la rge s ide cha ins whic h

c on ta in a m ino , c a r boxy l , su lph ide g r oups a nd r e l a t ive ly 50 % o f the we igh t o f woo l



1 2 K i n d s o f F i b r e s

T A B L E 1 . 8

A m i n o A c i d C o n t e n t i n W o o l K e r a t in

R A m i n o a c id W o o l c o n te n t

( g / 1 0 0 g f i b r e )

F i b r i o n c o n t e n t

( g / 1 0 0 g f i b r e )

H - G l y c i n e 5 - 7 3 6 - 4 3

C H 3 A l a n i n e 3 - 5 2 9 - 3 5

(CH3)2CH - V a l m e 5 - 6 2 - 4

( C H 3 ) 2 C H C H 2 L e u c i n e 7 - 9 0 - 1

C H 3 C H 2 C H I s o le u c i n e 3 - 5 0 - 1

O

C - P r o l i n e 5 - 9 0 - 1

~ ~ C H 2 P h e n y l a l a n i n e 3 - 5 1 - 2

O H - 4 ~ C H 2 - T y r o s in e 4 - 7 1 0 - 1 3

C H 2

H

T r y p t o p h a n 1 - 3 0 - 1

H O C H 2 - S e r i n e 7 - 1 0 1 3 - 1 7

C H 3 C H - T h r e o n i n e 6 - 7 1 - 2/

O H

- C H 2 S S C H 2 - C y s t i n e 1 0 - 1 5 0

C H 3 S C H z C H 2 - M e t h i o n i n e 0 - 1 0

N HII

N H 2 C N H ( C H 2 ) 3 - A r g i n i n e 8 - 11 0 - 2

/ ~ H2-H N \ H i s t i d i n e 2 - 4 0 - 1

NH 2(CH2) 4 - L y s i n e 0 - 2 0 - 1

H O O C C H 2 - A s p a r t i c a c i d 6 - 8 1 - 3

H O O C ( C H 2 ) ~ - G l u t a m i c a c i d 1 2 - 7 1 - 2

is i n t h e s id e c h a in s . T h e c y s t i n e l in k a g e a n d i n t e r m e d i a t e h y d r o g e n b o n d i n g a re




re s pon s i b l e fo r t he s ha p i ng a nd s e t t i ng c ha ra c t e r i s ti c s o f w o o l f i b r e s a nd f a b r i c s .

C ys t i ne l inka ge s c a n oc c u r w i t h i n a nd be t w e e n w oo l po l yme r s . 35% of the e xoc u t i cl eA - l a ye r i s m a de up o f c ys t ine r e s i due s a nd i n a dd i t ion t o no rm a l po l ype p t i de bonds ,

t he c u t i c l e is c ros s - l i nk e d by i s od i pe p t i de bo nds [ e - ( ~ / - g l u t a m yl ) l y s i ne ] . The

p o l y m e r s y s t e m o f w o o l i s e x t r e m e l y a m o r p h o u s a s it i s a b o u t 2 5 - 3 0 % c r y s t a l li n e

a nd 7 0 - 7 5% a m orph ous . M od e m v i e w s [ 50 , 51 ] a s s e r t t ha t t w o o r th r e e p ro t e i n

c ha i ns ( s om e o f w h i c h a r e o t - he l i c a l i n s truc t u r e ) c o i l roun d t o fo rm a p ro t o f i b r i l,

a doz e n o f w h i c h a g gre g a t e to fo rm mi c ro - f i b r i ls . The s e a r e l oc a t e d i n c l o s e a r r a y

w i t h i n a m a t r i x o f p ro t e i n ma t e r i a l r i c h i n c ys ti ne bu t w i t h l i tt le s t r uc t u r a l r e gu l a r -

i ty , pa r a c o r t e x c on t a i n i ng m ore o f t he ma r t i x . Th i s t w o pha s e s t ruc t u r e g i ve s r is e

t o t he mi c ro - f i b r i l s obs e rve d i n t he c o r t e x a nd po i n t s to the e x i s t e nc e o f m ore t ha n

one p ro t e i n i n w oo l .

1 .4 .2 I m p u r i t i e s in r a w w o o l

R a w w oo l i s d i r t y a nd a bou t 5 0 % o f i ts w e i gh t c ons i s t s o f na t u r a l a nd o t he r

i mpu r i t ie s ( Ta b l e 1 .9 ). I n ge ne ra l , the f i ne r w o o l s s uc h a s me r i no c on t a i ns a h i ghe r

T A B L E 1 . 9 .

I m p u r i t i e s i n R a w W o o l ( in % )

Type Fa t a nd s u i n t S a nd a nd d i r t V e ge t a b l e ma t t e r W ool f i b re

F i ne 20 -50 5 -40 0 . 5 -2 20 -50

M e di u m 15-30 5 -20 1 .5 40 -6 0

L on g 5 -15 5 -10 0 . 2 6 0 -8 0

p r o p o r t i o n o f n a t u r a l i m p u r i ti e s t h a n th e c o a r se w o o l . T h e c o n t a m i n a n t s a l so v a r y

a c c o rd i ng t o b r e e d , ne u t r i t i on , e n v i ron m e n t a nd pos i ti on o f w o o l on the s he e p .W a x , s u i n t a nd d r i e d pe r s p i r a t i on a r e na t u r a l a nd d i r t ( a dve n t i t i ous ) , g r a s s , s e e ds,

s t r a w , bu r r s , b r a m bl e s , s t i c ks e tc . ( ve ge t a b l e ma t t e r ) a r e a c qu i r e d i mpur i t i e s . The

p r e s e n c e o f p r o t e i n a c e o u s c o n t a m i n a n t l a y e r (P C L ) i s a l so f o u n d [ 5 0 ].

C h e m i c a l l y w o o l w a x i s a c o m p l e x m i x t u r e o f es te r s, d i e s te r s a n d h y d r o x y

e s t e r s o f h i gh mo l e c u l a r w e i gh t l a no l i n a lc oho l a nd a c ids . The l a no l i n a l c oho l

c ons i s t s o f t h r e e m a i n t ype s - a l i pha t ic a l c oho l s , s t e ro l s ( s uc h a s c ho l e s t e ro l ) a nd

t r i me t hy l s t e ro l s ( s uc h a s la nos t e ro l s ). The l a no l i n a c i d c ons i s t s o f fou r ma i n t ype s

- no rm a l , i so , a n t e i s o a nd hy drox y a c i ds. O n e xpos u re t o t he e nv i ronm e n t w oo l

r e a d i l y u n d e r g o e s a u t o - o x i d a t i o n . T h e r e a c t i o n p r o d u c t ( o x i d i s e d w o o l w a x ) b e -




h av e s d i f f e r en t ly f r o m u n o x id i s ed m a te r i a l [ 51 ] . T h e d i f f e r en ces m an i f e s t th em -

s e lv es i n th e s co u r in g p r o ces s o f w o o l .Su in t i s m a in ly w a te r s o lu b l e cq n s t i t u en t s o f r aw f leece an d i s n o r m a l ly n eu t r a l

o r s l igh t ly a lka l ine in r eac t ion . I t con ta ins po ta ss ium and to a cer ta in ex ten t sod ium

ions.

T h e ce l l u lo s i c m a te r i a l s a r e f i n e ly en t an g l ed w i th t h e w o o l f i b r e an d r eq u i r e

ch em ica l t r ea tm en t s f o r t h e i r r em o v a l . As w e l l a s t h e ce ll u lo s e t h e w o o l b u r r s a l so

co n ta in h em i - ce l l u lo s e an d li g n in .

1 .4 .3 M o r p h o l o g y a n d c h e m i c a l s t r u c tu r e o f s il k

Si lk f ib r e i s a fi n e co n t in u o u s s t r an d u n w o u n d f r o m th e co co o n o f a m o th ca t e r -

p i l l a r k n o w n as s i l k w o r m . T h e s i l k w o r m as a m ean s o f s e l f - p r o tec t i o n s p in s a

co co o n a r o u n d i ts b o d y b y e x t r u d in g t h e co n t en t s o f th e tw o s i lk g l an d s t h r o u g h a

s p in n e r e t t e a t it s m o u th . T h e tw o f i l am en t s s o l id i f y o n co m in g in co n t ac t w i th a i r

an d f o r m a co m p o s i t e t h read . T h e s i l k w o r m s a r e g en e r a l l y cu l t iv a t ed . T h e r e a re

m a in ly f o u r v a r i e ti e s o f s il k e .g . Mu lb e r y , T as s a r , E r i an d M u g a an d each v a r i e ty is

p r o d u ce d b y f eed in g o n t h e l eav es o f ce r t a in p l an t s . A l l t h e s p ec i e s o f s il k h av e

f o u r s t ag es i n t h e i r l if e cy c l e s n am e ly , t h e eg g , l a r v a , p u p a an d m o th . T h e m u lb e r ys i l k w o r m b e l o n g s t o th e s p e c i e s B o m b y x m o r i a n d a b o u t 9 5 % o f t h e w o r l d 's p r o -

d u c t io n i s o f t h i s sp ec i e s . T h e o th e r t h r ee v a r ie t i e s a re p r o d u ced b y t h e w o r m

An th e r ae a m y l i t t a an d a re t e r m ed a s w i ld si lk . T h e y a r e st i ff e r an d co a r s e r th an

m u lb e r y s i lk . Ra w s i l k t h r ead i s o b t a in ed f r o m s i l k co co o n s b y r ee l i n g a f t e r b o i l -

i n g t h e co co o n s i n w a te r . Sev e r a l s u ch th r ead s a r e d o u b led t o g e th e r an d tw i s t ed

in to a s t r o n g y am n ece s s a r y f o r w e av in g an d k n i tt i n g .

T h e m o r p h o lo g i ca l s t ru c tu r e o f r aw s i lk fi b re i s g iv en i n F ig . 1 - 10 . T h e ac tu a l

f i b re p r o t e in i s ca l l ed f i b r io n an d t h e p r o t e in s e r ic in i s t h e g u m m y s u b s t an ce t h a t

h o ld s t h e f i l am en t t o g e th e r . T h e av e r ag e co m p o s i t i o n o f r aw s i l k i s 70 - 75 % f ib r io n

(C~sH23NsOs), 20-2 5% ser ic in , 2 -3% w ax y su bs tanc es e x t r ac tab le by e the r and a l -

co h o l an d 1 t o 1 . 7% m in e r a l m a t t e r . Se r i c in i s am o r p h o u s an d d i s s o lv es i n h o t

s o ap s o lu t i o n . F ib r io n i s t h e f o r m o f a f i lam en t t h r ead an d d i s s o lv es i n 5 % s o d iu m

h y d r o x id e s o lu t i o n a t b o i l.

Bo th f i b r io n an d s e r i c in a r e p r o t e in s u b s t an ces b u i l t u p o f 1 6 - 18 am in o ac id s ,

o u t o f w h ich o n ly g ly c in e , a l an in e , s e r in e an d t y r o s in e m a k e u p t h e l a r g es t p a r t o ft h e s i l k fi b r e ( s ee T ab l e 1 .8 ) an d t h e r em a in in g am in o ac id s co n t a in in g b u lk y s id e

g r o u p s a r e n o t s i g n if i can t. T h e c h em ica l s t r u c tu r e o f f i b rio n an d s e r i c in f o r fo u r





16 Kind s o f F ibres

/ \ /R H C C H B R H C

\ / \C ~.-~0- --H--N C ~0- -.

/ \ /- - H - N C - ~ O - - -H- 'N

\ / \CHI~ RHC CHR

/ \ /-,, -O ~ C N-H-- -O ~ C

\ / \N - H - - - - O ~ C N -- H- -

/ \ /RHC CHR RHC

\ / \C . ~ O - - H - N C ~ O -

/ \ /- -H -N C - ~ O - - H - N

\ / \

Figu re 1 -11. Crys ta l l ine s t ruc tu re o f po lyp ep t ide c ha ins in f ib r ion .

F igure 1 -12 . Lam inate d s t ruc tu re o f si lk .

in d iam eter a long the f ib re . The f ib res a re bas ica l ly t r i angular in c ross -sec t ion wi th

ro u n d ed co m ers . T h e i s o e lec t r ic p o i n t o f si lk is ab o u t 5.

1 .5 Long Vegetable F ibres

The long ve getab le f ib res inc lude v ar ious bas t f ib res , l eaf fib res and f ru i t f ib res .

Am on g the bas t f ib res fl ax , rem ie , ju te a re the m os t impo r tan t f ib res . The se f ib res ,

w h i ch a r e u s ed i n co rd ag e h av e s u f f e r ed a l o n g w i t h ab aca , co i r , h en eq u een an d

s i sa l fib res as they a re unab le to wi ths tan d the ons laugh t o f syn the t i c f ib re corda ge

techno logy. Thus, the long vegetable f ibres wi th thei r l imi ted and f luctuat ing grow th

ra tes , can not cop e wi th rap id r ise in g loba l dem and fo r indus t r i a l t ex t i les . The ad-

van tage o f these f ib res i s tha t they a re e co- f r i end ly f ib res .



Kinds o f F ib r e s 17

1 . 5 . 1 F l a x ( l i n e n )

Fla x i s a ba s t f ib r e u se d to m a nu f a c tu r e l i ne n te x t i le s . I t i s ob ta ine d f r om p la n tL i n i u m U s i t a t i s s im u m b y a c o m p l i c a te d p r o c e s s to s e p a ra t e f ib r e f ro m t h e w o o d y

c or e . Th i s p r oc e s s know n a s r e t t ing a nd c a n be done by de w r e t t i ng [52 ] , poo l

r e t t ing , t a nk r e t ti ng , s t e a m r e t t i ng [53 - 55 ] , c he m ic a l [56 - 59] a nd b io c he m ic a l r e t -

t ing . Af te r re t t i ng is c om ple te , t he s t a c k i s bun d le d toge the r a nd pa s se d be tw e e n

f lu t te d r o l l e r s tha t b r e a ks the ou te r woo dy c o ve r ing in to sm a l l pa r t ic l e s . I t i s t he n

subjec ted to scutching process , which sepera tes the oute r cover ing f rom the unusuable

f ib r e . Af t e r s c u tc h ing , t he f l a x f ib r e s a re ha c k le d o r c om b e d to s e pa r a t e the sho r t

f ibres ( tow) f rom the long f ibres .

F la x i s c ons ide r e d to be the o lde s t f ib r e in the We s te r n w or ld a nd C I S ( f o r m e r ly

US S R ) g r ow s m os t o f t he f la x fib re . L ine n ha s be e n g r a dua l ly loos ing i t s pos i t ion

a s an a ppa r e l f a b r i c s inc e 19 50s , bu t t he e m e r g e nc e o f l i ne n a s a c om pon e n t o f

b le nds ha s s t im u la t e d c ons ide r a b le in t e re s t .

F la x f ib r e s a r e m u l t i c e llu l a r , w i th e a c h c e l l ha v ing t a pe r ing e nds a n d a na r r ow

lum e n . The f ib r e s show long i tud ina l s t ri a tions a nd node s ( F ig . 1 -13). The u l t im a te

F igur e 1 - 13. C r oss - se c t ion o f f l ax f ib r e ( E . I .Du Pom de N e m ou r s & C o . ) .

f ib r e s a r e c om pose d o f e l e m e n ta r y f ib r il s ( m ic r o f ib r i ls ) , w h ic h a r e sp i r a lly a r r a nge d

[6 0] . The f ib ri l s a r e he ld toge the r by a bon d ing o r gu m m y sub s ta nc e s .

C e l lu lo se i s t he m a in c o ns t i tue n t s o f f la x f ib re ( F ig . 1 - 14). The u n r e t t e d f l a x

c on ta ins a bou t 16 .7 % he m ic e l lu lose , 1 .8 % pe c t in s , 2% l ign in a nd 1 .5% f a t s a nd

w a x e s . T h e p o l y m e r o f f la x c o n s is t s w i th a d e g r e e o f p o l y m e r i s a t io n o f a b o u t

18 0 00 c e l lob iose un i ts . F l a x is a n a s se m b ly o f u l t im a te s c e m e n te d tog e the r w i th in

the f ib r e s a nd a n a s se m bly o f the se f ib r e s in to bund le s . The se a s se m bl i e s a r e p r one



18 Kind s o f F ib r e s

H O H H O HI I I I

H .OH C " .OH

o /C O O H C 0 H

H O ~ H O H c/ /I I

H H

Figur e 1 -14 . C he m ic a l c on s t i tu t ion o f f la x .

( 6 4% C e l lu lose + 16 % He m i- c e l lu lose ) .

to d i sc o lou r a t ion [61 ] . I t i s t he s t r uc tu r e wh ic h m a ke s l i ne n f e e l li ke li ne n . F la x

ha s r e l a t ive ly h igh s t r e ng th . D i s r up t ion o f s t ruc tu r e by , f o r e xa m ple , s c our ing r e -

f e r r e d to a s c o t ton i sa t ion .

1 . 5 . 2 R e m i e

R e m ie f ib r e is wh i t e a nd lu s t r ous a nd o f t e n re f e r r e d to a s c h ina g r a s s . R e m ie

ha s be e n g r ow n in B r a z i l to subs t i tu t e f la x . The f ib re i s s t if f a nd f a i r ly c oa r se l ike

c a n v a s . T h i s f i br e c o m e s f r o m p l a n ts B o e h m e r i a n iv e a o r B o e h m e r i a t e n a c i s s e m a

w hic h be lo ng to a f a m i ly o f s t ing le s s ne t t le s . The r e m ie f ib r e s a r e r e m ov e d f r om

the s t a lks by the p r oc e s s o f de c o r t i c a t io n . The f ib r e s ar e r e l e a se d f r om r ibbons o r

s t ra n d s i n w h i c h t h e y ar e h e l d to g e t h e r b y n a t u ra l g u m s . C o m m e r c i a l d e g u m m i n g

i s c a r r i e d ou t by t r e a t ing the fib r e s w i th c a us t i c soda so lu t ion f o r 4 h . The use o fm ixe d ba c te r i a l c u l tu r e s [62 ] a nd e nz ym e s [6 3 ] a r e al so r e por t e d to r e m ov e the gum

f r om r e m ie f ib r e .

Pur i f i e d r e m ie f ib r e i s c om pos e d o f a s ing le c e llu lose w i th wa l l w i th a n S - sp i r al

6 o to the a x i s [6 4 ,6 5 ] . R e m ie ha s the h igh e s t de g r e e o f bo th po lym e r i sa t ion a nd

b i r e f r inge n c e s . Th e h igh s t r e ng th o f r e m ie i s a t t r ibu te d to i ts h igh ly o r de r e d s t ruc -

ture . Th e c rys ta l l ine a reas inc rease in la te ra l s ize and decrea se in c rys ta l l ine or ien-

t a t ion a s the gu m i s r e m ov e d f r om the in t e r c r ys t a l l ine a r e a s [66 ].

R e m ie f ib r e s te nd to ha ve a ha i r y fe e l w h ic h r e duc e s the i r c ohe s ion . Th e y a r e

sm oo th a nd c y l ind r i c a l , w i th th i c k wa l l. The su r f a c e o f the c el l is m a r ke d by l i t tl e



Kind s o f F ib r e s 19

r idge s . Th e c e l l o f t he f ib r e is l ong a nd the c ros s - se c t ion i r r e gu la r in sha pe . The

l u m e n n a r r o w s a n d d i s a p p e a r s to w a r d s t h e e n d s o f t h e ce ll . R e m i e f i b re a b s o r b sw a te r ra p id ly a nd f a b r i c s m a d e f r om i t w i l l l a unde r e a s i ly a nd d r y qu ic k ly .

1 . 5 . 3 H e m p

He m p c o m e s f r om the p la n t , C a nna b i s S a t iva , an a nnua l o f t he f a m i ly M or a c e a e ,

w h i c h g r o w s t o a h i g h t o f 1 0 f e et o r m o r e . T h e m o s t i m p o r t a n t h e m p p r o d u c i n g

c oun t r i e s a r e C . I.S ., Yugo s la v ia , R u m a n ia a nd Hunga r y . F ib r e is fr e e d f r om woo dy

m a t t e r by a re t t i ng p r oc e ss , f o l lowe d by b r e a k ing a nd sc u tc h ing . Th i s i s t he n so f t -

e n e d b y p o u n d i n g i t m e c h a n i c a l l y o r b y h a n d . H e m p h a s c e l l u lo s e c o n t e n t o f ab o u t

6 7 % a n d c o n t a i n s a b o u t 1 6 % h e m i c e ll u l o s e . S t ra n d s o f h e m p f ib r e m a y b e 6 fe e t

o r m or e in l e ng th . The ind iv id ua l c e l l i s, on a ve r a ge be tw e e n 0 .5 a nd 1 inc h long .

Th e y a r e c y l ind r i c a l i n sha pe wi th jo in t s , c r a c ks , sw e l l ing a nd o the r i r r e gu la r i t ie s

on su r f a c e . L ike f l a x , t he c e l ls o f he m p f ib r e a r e th i c k wa l l e d , t he y a r e po lygon a l i n

c r os s - se c t ion . Th e c e n t r a l c a na l o r l um e n i s b r oa d e r tha n tha t o f fl a x , how e ve r , t he

e nds o f the c e l l s a r e b lun t .

T h e f ib r e w i l l n o t b l e a c h e a s i l y a n d g e n e r a l ly e m p l o y e d i n th e m a n u f a c t u r e o f

r ope s , tw ine s , s a c k ing , c a r pe t s , ne t s a nd ta r pa u l in s . I n a dd i tion , he m p a l so se r ve stoda y a s a r a w m a te r i a l f o r pa p e r indus t ry . C o t ton i se d he m p doe s no t sp in e a s ily

a lone , bu t it g ive s u se f u l ya r n , whe n m ixe d w i th c o t ton ( up to 50 % he m p) .

1 .5 .4 J u te

Ju te i s a lso a l i gnoc e l lu los i c b a s t f ib re a nd i s c u l t iva t e d in a m a n ne r s im i l a r t o

tha t o f f la x . Ju t e i s m a in ly g r ow n in I nd ia , B a ng la d e sh a nd Tha i l a nd . Ju te f ib re

c om e s f r om h e r ba c e o us a nnu a l p l a n t w h ic h g r ow s a s h igh a s 20 f e et . Ju t e fib r e s ar e

e x t r a c t e d f r om the s t e m by r e t t ing w h ic h usua l ly c ons i s t s two s t a ge s : phy s ic a l

s t a ge a t w h ic h w a te r i s im b ibe d , sw e l l ing oc c u r s , so lub le subs ta nc e s a r e e x t r a c t e d

a nd the m ic r ob ia l s t a ge . Ju t e t e nds to be b r ow n in c o lou r due to a bou t 20 % l ign in

p r e se n t i n the f ib r e , bu t doe s h a ve a s i lk li ke lu s t re .

Th e ind iv idua l c e ll s o f j u t e a r e ve r y sho r t. Ta b le 1 .11 c om pa r e s the d im e n s ion

of u l t im a te f r om se ve r a l sou r c e s . The c r os s - se c t ion o f ju t e f ib re is po ly gon a l , u su -

a l ly w i th f ive o r s ix s ide s . I t ha s th i c k wa l l s a nd a b r oa d lum e n o f ova l c r os s -

se c t ion . B y c on t r a s t w i th the r e gu la r l um e n o f f la x , tha t o f j u t e i s i r r e gu la r ; i t

b e c o m e s n a r r o w i n p l a c e s q u i te s u d d e n l y . T h e l e n g t h s o f v a r i o u s v e g e t a b l e f ib r e sva r i e s c ons ide r a b ly , w he r e a s the d i a m e te r is m ode r a t e ly c on s ta n t f r om f ib r e to f i-

bre .




T A B L E 1 . 1 1

C o m p a r i s o n o f t h e D i m e n s i o n s o f L o n g V e g e t a b l e F i b re s [ 6 7]F ib r e Len g th Diam e te r As p ec t r a t i o

( m m ) ( n m )

M ar in o 4 . 6 - 5 . 2 1 7 . 0 -2 1 . 4 2 5 5

C oir 0 .9-1 .2 16 .2 -19 .5 60

Flax 27 .4-36 .1 17 .8-21 .6 1600

T r u e He m p 8 .3 - 1 4 .1 1 7 . 0 -2 2 . 8 5 60

Su n n He m p 3 . 7 - 6 .0 2 3 . 0 - 3 5 . 0 1 70

Ju te (Ca psu lar i s ) 1 .9-2 .4 16 .6-20 .7 115

Ju te (Cor . Ol i to r ius ) 2 .3 -3 .2 15 .9-18 .8 160

K en af 2 . 0 - 2 .7 1 7 . 7 -2 1 . 9 1 2 0

Rem ie 1 2 . 5 - 1 2 .6 2 8 . 1 - 3 5 . 0 4 000

M esta 2 .6-3 .3 18 .5 -20 .0 150

Sisal 1 .8-3.1 18.3-2 3.7 120

Ur e n a 2 . 1 - 3 . 6 1 5 . 6 - 1 6 .0 1 80

In f lax t h e u l tim a te s a r e m u ch lo n g e r th an t h o s e i n j u t e , s i sa l an d co ir . T h e

im p l i ca t i o n o f t h i s o b s e r v a t i o n i s t h a t t h e ' c em en t ' c an b e r em o v ed f r o m th e f l ax

w i th l it tl e e f f ec t o n t en s i le s t r en g th a s h y d r o g en b o n d in g s ti ll o ccu r s o v e r t h e l a r g e

co n tac t a r eas o f t h e u l tim a te s . In th e ca s e o f f ib r e s w i th s h o r t u l t im a te s , s u ch b o n d -

i n g d o e s n o t o c c u r a n d r e m o v a l o f t h e c e m e n t c a u s e s m a s s i v e s t r e n g t h lo s s.

J u t e f i b re s a r e b u n d le s o f f i b ro u s m a te r i a l h e ld t o g e th e r b y a g u m m y s u b s t an ce

o f p r o t e in a ceo u s ch a r ac te r . Ch em ica ll y , j u t e f i b re s a re co m p o s ed o f m a in ly p o ly s ac -

c h a r i d e s a n d l ig n i n , a lt h o u g h t h e n u m b e r o f m i n o r c o m p o n e n t s , s u c h a s w a x e s ,

pec t in , inorga n ic sa lt s , n i t rogeneou s subs tances , co lour ing m at te r e tc ., a r e a l so found .

T ab le 1 .1 2 co m p ar es t h e co n s t i tu t i o n o f co t t o n w i th f l ax an d j u t e . T h e t o t a l ca r b o -

h y d r a t e m a te r i a l i s u s u a l l y d es ig n a t ed a s h o lo ce l l u lo s e , w h ich i s f u r th e r d iv id ed

in to tw o g r o u p s , n am e ly (x - cel lu lo se ( tr u e ce ll u lo s e ) an d h em ice l l u lo s e . Ce r t a in

f r ac t io n s o f t h e h em ice l l u lo s e m ay b e ch e m ica l l y l i n k ed w i th t h e t r u e ce ll u lo s e .T h e f o r m a t io n o f m ix ed c r y s t a l s is p o s tu l a t ed . L ig n in i s g en e r a l l y r eg a r d ed a s a



Kin d s o f F ib r e s 2 1

T A B L E 1 . 1 2

C o m p a r i s o n o f t h e C h e m i c a l C o n s t i tu t i o n o f Ju t e w i th F l a x a n d C o t t o n

C h e m i c a l C o t t o n F l a x

co n s t i t u ti o n av e r ag e Re t t ed Un r e t t ed

Jute

Ce l lu lose 88-96 55 .4 65 .1 58-63

Hem ice l l u lo s e - - 1 5 .4 1 6 .7 2 1 - 2 4

Pect ins 0 .7-1 .2 2 .5 1 .8 0 .2 -15

Lign in - -

Pro te ins 1 .1 -1 .9

2.5 2 .0 12-15

0.8-1 .8

F a ts & W ax e s 0 .4 -1 .6 . . . . 0 .4 -0 .8

A s h (% ) . . . . . . 0 .6 -1 .2

t h r e e - d i m e n s i o n a l p o l y c o n d e n s a t e o f d e h y d r o g e n a t i o n p r o d u c t s o f h y d r o x y a n d

m e th o x y c in n am y l a l co h o ls . T h e ex i s t an ce o f e s t e r- li n k ag e b e tw een ca r b o x y l g r o u p s

i n u r o n i c a c i d o f h e m i c e l l u l o s e a n d h y d r o x y l g r o u p s o f l i g n i n i s f o u n d. I n g e n e r a l

p l an t l i g n in r e s i s t s t h e ac t i o n o f ac id s t o a g r ea t ex t en t. Co i r w i th h ig h es t l i g n inc o n t e n t ( 3 5 % ) i s m o s t r e s i s ta n t t o c h e m i c a l s a n d m i c r o - b i o l o g i c a l a t ta c k . V a r i o u s

p r o p e r t i e s o f j u t e f i b re s a r e co m p ar e d w i th fl ax in T ab l e 1 .1 3 . J u t e is n o t a s st r o n g

T A B L E 1 . 1 3

P r o p e r t i e s o f Ju t e an d F l ax F ib r e s

P r o p e r ty E v a lu a t i o n

Flax Ju te

Lu s t r e Hig h S i lk y

St ren g th ( tenac i ty ) 6 .5 g /d 3 .5 g /d

R e s i li e n c y P o o r L o w

De ns i ty 1 .54 1 .50

M o i s t u re a b s o r p ti o n

at 20~ 12% 13 .7%

as f lax o r h em p . J u t e f ib r e s a r e s t if f, b u t d o es h av e an u n u s u a l ly h ig h m o i s tu r e

r e g a i n . S u n l i g h t d o e s n o t d a m a g e j u t e .




1 . 6 R e g e n e r a t e d N a t u r a l F i b r e s

T h er e a r e th r ee t y p es o f r eg en e r a t ed n a tu r a l f i b re s - r ay o n , acc t a t e an d p r o t e in -t h e f i rs t tw o a r e d e r iv ed f r o m co t to n l i n te r s o r p in e w o o d . W o o l l i k e p r o t e in b as ed

a r t if i c ia l f i b r e s m a y b e r eg en e r a t e d f r o m an im a l an d v eg e t ab l e p r o t e in s .

1 . 6 . 1 C u p r a m m o n i u m r a y o n

T h e p r e p a r a t i o n p r o c e s s o f c u p r a m m o n i u m r a y o n i s s h o w n i n F ig . 1 -1 5 . I n

pur i f ied ce l lu losea que ous ammonia---- .-- ,_ I ]

ba s ic c oppe r s u l pha te = | lcaust ic s o d a - ~ _ _ ~

n ic k e lga uze f i l t e r

- l l l [ l l l i ! i l l ~ - ]

~-~s toragew~P~af~t~ --Iminnerette

s u l phur ic a c id ~of

to winding,wa s h ing .lubrication.a nd d r y ing

F i g u r e 1 -1 5 . F l o w c h a r t s h o w i n g p r o c e s s o f c u p r a m m o n i u m m a n u f a c t u re .o r d e r t o m ak e a sp in n in g d o p e t h e b as i c co p p e r s u lp h a t e i s d i s s o lv ed i n am m o n ia ,

g iv in g a s o lu t i o n o f cu p r i t e t r am m in o h y d r o x id e an d s u lp h a t e i n t h e m o lecu l a r r a t io

o f 3 : 1 an d p u r i f i ed l i n t e rs a r e ad d ed . Cau s t i c s o d a i s t h en ad d ed t o co n v e r t th e

s u lp h a t e t o co r r e s p o n d in g h y d r o x id e an d f il t e red [68 ]. T h e ch em ica l reac t i o n s a r e

g ive n in F ig . 1 -16.

C6H7Oz(OH)3 + Cu(NH4OH ) ---->C6H702(OH) : Cu(NH 4OH )

H2SO 4

C6H702(OH)3

F i g u r e 1 -1 6. F o r m a t i o n o f c u p r a m m o n i u m r a y o n .

T h e s p in n in g s o lu t io n i s p u m p ed th r o u g h th e s p in n e r e t t e i n to a fu n n e l t h r o u g h

w h i c h s o f t w a t e r i s r u n n i n g . T h e m o v e m e n t o f w a t e r s t re t c h es t h e n e w l y f o r m e d

f i lam en t . T h e f i b r e s t h en m o v e t o s p in n in g m ach in es , w h e r e t h ey a re w as h ed , p u t

t h r o u g h a m i ld ac id b a th t o r em o v e an y ad h e r in g s o lu t io n , r i n s ed an d tw i s t ed i n to

y a m s .

1 . 6 . 2 V i s c o s e r a y o nP u r i f i ed b l eac h ed w o o d p u lp o r s h ee t s o f ce l l u lo s e a r e s t eep ed i n an a lk a l i s o lu -



Kinds o f F ib res 23

t ion (17.5%) unt i l the ce l lu lose i s conver ted to soda-cel lu lose . The a lkal i pulp i s

then shred ded in to a lkal i ce l lu lose crum b, which i s aged for speci f ic time. Thecrum bs a re t hen t rea t ed wi th ca rbon d i su lph ide and p roduce sod ium ce l lu lose xan -

tha te . Th i s i s d i s so lved i n d i lu t e sod ium hyd rox ide and fo rms a honey c o lou red

l iquid and aged t il l requ i red v i scos i ty i s obta ined . The v i scous so lu t ion i s pu m pe d

to t he sp inn ing t anks , de l ive red t o the sp inn ing mac h ines , fo rced by pum p th rou gh

a sp inneret te in to a d i lu te ac id bath (Fig . 1-17). The m etho d of m akin g f ibre i s

F igu re 1 -17. Vi scose r ayon m anufac tu r ing p roces s .

ca l led wet -sp inning . The che mica l changes that occured in the proce ss are out lined

in Fig . 1-18. In the m id- 1960s f ibres w i th h igher we t s t re tch , low w et ex tens ib i l i ty

and a h igh we t mo du lus (HW M ) a re p roduced and known as 'po lynos i c ' o r 'moda l '

t ype f ib res . H W M f ib res a re genera l l y p roduced [69,70] by add ing mod i f ie r s , e .g .

va r ious am ines o r po ly ( e thy l ene) g lyco l t o the v i s cose t o con t ro l t he r a te o f r egen-

e ra t ion o f t he f i l ame n t i n the coag u la t i on ba th . Th ey a re usua l ly p rod uced as s t ap l e

fibre.

Vi scose and mo d i f i ed v i s cose a re com posed o f ce ll u lose and l ike co t t on they

are po ly m er o f anhydrog lucose un it . The s ign i fi can t phys i ca l d i f fe rences be twe en

var ious r egenera t ed ce l l u lose and co t t on po lym ers a re li s ted i n Tab l e 1 .14 . HW Mviscose r ayon may app ear nea r ly round in c ros s -sec t ion . Vi scose po lym ers a re

very amo rphous and have h igh moi s tu re abso rp t ion capac i t y o f 11 t o 16% . Vi s -




CIH2OH H OHt I

I I I

H OH C H2OH

\E a c h h y d ro x y l g r o up is r e p re s e n te d b y " - C - O H

/\ , , / /S

For m a t ion o f x a n t ha te e s t e r" - C - O H + C S 2 + OH- ~ /-- -C -O-C/ NS -

R e g e n e r a te d v i sc o s e r a y o n" - O - H § ~ - ~ - O H + C S 2

Figure 1-18 . Viscose process .

+ H 2 0

T A B L E 1 . 1 4

S ign i f i c a n t Phys ic a l D i f f e r e nc e s B e twe e n R a yon a nd C o t tonP o l y m e r Approx. no .

o f c e l lob iose

units

Appr ox . Appr ox . Appr ox .

p o l y m e r p o l y m e r d e g r e e o f

l e ng th ( ra m ) th i c kne ss ( nm ) po lym e s i sa t ion

Visco se 175 180 0 .8 175

Poly nos ic 300 310 0 .8 300

C u p r a m m o n i u m 2 5 0 2 6 0 0 .8 2 5 0

r a y o n

Co t ton 5000 5000 0 .8 5000

c ose sho ws no d i sc e r n ib le m ic r o - s t r uc tu r e , bu t po lynos ic shows a d i s t inc t f ib r il l a r

structure s im ilar to cotton. Viscose f ibres sho w longitud inal s tr ia tions ( t iny groov es) ,

b u t c u p r a m m o n i u m a n d p o l y n o s i c a re c o a g u l a te d m u c h m o r e s l o w l y o n e x tr u s io n ,

do no t de ve lop a ny s tr i at ions . Fo lde d c ha ins m ode l ha ve be e n p r opose d [71 ] f o r

the f ine s truc ture of v iscose rayon (Ce l lu lose I I) . The d i f fe rence be tw een C e l lu lose I

a nd C e l lu lose I I f a m i l i e s a ppe a r s in the a r r a nge m e n t o f po la r i ty o f f o lde d c ha ins

p r oduc e d f r om the c e l lu lose m ole c u le s [7 2 ] .



K i n d s o f F i b r e s 2 5

1 . 6 . 3 A c e t a t e f i b r e s

I n t h i s g r o u p t h e r e a r e t wo f i b r e s : s e c o n d a r y c e l l u l o se a c e t a t e a n d t r i a c e t a t ef ib r e s. A c e t a t e f i b r es a r e p r o d u c e d f r o m c o t t o n li n t er s o r p u r i f i e d w o o d p u l p ,

w h i c h a r e a c e ty l a t e d at t e m p e r a t u r e u p to 5 0~ w i t h a c et ic a n h y d r i d e i n p r e s e n c e o f

g l a c i a l a c e t ic a c i d a n d c o n c e n t r a t e d su l p h u r i c a ci d . I t i s t h e n a g e d o r r i p e n e d i n

p r e s e n c e o f w a t e r a n d h y d r o l y s i s o c c u r s d u r i n g t h e r i p e n i n g a n d r e s u l ts i n t h e f or -

m a t i o n o f s e c o n d a r y a c e t at e . T h e f l a k e s ar e t h e n d i s s o lv e d i n a c e t o n e c o n t a i n i n g

4 % w a t e r a s th e s o l v e n t t o f o r m t h e s p i n n i n g d o p e , w h i c h i s f il te r e d a n d t h e n f o r c e d

t h r o u g h t h e s p i n n e r e t t e i n t o a w a r m - a i r c h a m b e r a n d t h e m e t h o d o f s p i n n i n g i s

c a l l e d d r y - s p i n n i n g . T r i a c e t a te i s m a n u f a c t u r e d f r o m t h e s a m e r a w m a t e r i a l s as

s e c o n d a r y a c e t a t e , b u t th e r i p e n i n g s t a g e i n w h i c h h y d r o l y s i s o c c u r s i s o m i t t e d i n

t r i a c e ta t e p r o d u c t i o n . T o p r o d u c e s p i n n i n g so l u t io n , d r i e d a c e t a t e f la k e i s d i s so l v e d

in m e t h y l e n e c h l o ri d e a n d d r y - s p u n i n to a w a r m - a i r c h a m b e r .

T h e c h e m i c a l s t r u c t u r e o f a c e t a te f i b r es a r e s h o w n in Fi g . 1 - 1 9 . I n s e c o n d a r y

( C el lu lo s e ) - O H + ( C H 3 C O ) 2 0 H,_SO,> ( C e l lu l o s e ) _ O . C O . C H 3 +CH3COOH

H"x CH20OCCH3 ~ OOCCH3 /

?<

H OOCCH X'H H C H 2 0 O C C H 3

H

fJ

n = 1 5 0

Se c o n d a r y c e l l u l o se a c e t a t e

H CHzOCOCH H H\ ~ c ~ O ~ OCOCH3 r-,~

d " :c -oCH30~O XH H C H 2 O C O C H 3

T r i a c e t a t e f i b r e

F i g u r e 1 - 1 9. F o r m a t i o n o f c e l l u l o se a c e t a t e f ib r e s .

J

n = 225




a c e ta t e po lym e r , i t is the m e th y lo l h ydr ox y l g r oup tha t i s a c e ty la t e d a nd o ne o f the

o the r hydr o xy l g r oup . The o r e t i c a l ly be tw e e n 2 .3 to 2 .4 a c e ty l o r a c e ta l g r oups pe r

g luc ose un i t oc c u r in s e c onda r y c e l lu lose a c e ta t e po lym e r .

B o th type s o f a c e tat e f ib r es ha ve a po ly m e r " ba c kbo ne " o f he xa go na l un i ts .

The m a c r o s t r uc tu r e o f a c e ta te f ib re s i s ve r y s im i l a r t o tha t o f v i sc ose a nd d i sp la ys

no d i sc e r n ib le m ic r o - s t r uc tu r e s . Ac e ta t e f ib r e c om pl i c a t e s c lose pa c k ing be c a use

o f bu lk y s t r uc tu r e. B o th the f ib r es a r e a m or ph ous ( 6 0 % or le s s ) a nd a r e he ld to -

ge th e r by Van der W aa ls ' forces . Tr iace ta te has ce r ta in proper t ie s tha t a re d i f fe rent

f rom sec on dary ace ta te f ibres (Table 1 .15) . Seco nda ry ace ta te i s abou t 160 nm

T A B L E 1 . 1 5

C o m p a r i s o n o f P h y s i ca l P r o p e r ti e s o f A c e t a te F i b r e s

Prop er ty Secon dary Tr iace ta te

aceta te

Tenac i ty , g /den 1 .2-1 .5 1 .2-1 .4

E long a t ion , % 25- 45 25 - 45

R e c ove r y ( a t 4% e longa t ion ) , % 45- 6 5 50 - 65

M ois tu re rega in , % 6-6 .5 2 .5-3 .0

Spec i f ic gravi ty 1 .32 1 .32

M e l t ing po in t , oC 240 300

( f i lament)

(a t 5% s t re tching)

long a nd a bou t 2 .3 nm th i ck , w h i l s t the t ri a c e t a te i s a bou t 240 nm long a nd a bou t

2 .6 nm th ick . T r i a c e ta te s ha v e m uc h b e t t e r r e s i s ta nc e to bo i l ing wa te r a nd a lka li .

Tr iace ta te i s mo re expens ive than sec ondary ace ta te. Both the fibres can be b lended

wi th c e l lu los i c f ib r e s to ob ta in spe c ia l s ty l ing a nd pe r f o r m a nc e c ha r a c te r i s t i c s .

Te n de n c y o f ac e ta t e fib r es to de lus t r e in a que ous ba th a bove 8 0~ f o r ce to dye

the se f ib r es a t 7 5 -8 0 ~ g iv ing poor we t - f a s tne s s p r ope r t ie s . Th i s sho r t - c om ing o f

a c e ta t e ha s be e n r e m ove d r e c e n t ly ( X to l f ib r e s ) [7 3, 7 4 ].

1 .6 .4 Reg enerated p or te in f ibre s

The r a w m a te r i a l s u se d f o r the p r e pe r a tion o f r e ge ne r a t e d p r o te in f ib re s m a y be

m i lk , so ya be a ns , pe a nu t s a nd z ein . S om e t im e s a lka l ine so lu t ions o f ge l a tin , a lbu -

m in and o the r raw mate r ia ls l ike was te wool , s i lk and fea the rs ma y be used . F ibro lane

( Gr e a t B r e ta in ) a nd M e r ine va ( It a ly ) a re m a de b y d i s so lv ing c a se in in sod ium hy-droxide , and then by ext rus ion in to an ac id /sa l t ba th . The f ibres form ed in th is w ay



Kinds o f F ibres 27

is s t re tched as tow and par t ia l ly s tab i l ised by t rea tme nt wi th fo rm aldeh yde (F ig . 1 -

20).R - N H 2 + H C H O + H z N - R --4 R N H C H 2 N H R

Case in

+

[ - N H + C H 2 0 + N H -] -- - ~ [-- H N - C H 2 0 - N H - 1

Vicara |

F igure 1 -20 . R egene ra ted p ro te in f ib res.

The genera l p roper t ies o f regenera ted por te in f ib res inc lude the wool l ike a t -

t r ibu tes o f res i l ience , wa rm th and sof t hand le . The s t reng th i s low er than wool .

The se f ib res do no t con ta in cys t ine l inkage , wh ich resu l ts in more open s t ruc tu re .

These f ib res a re fa r less successfu l than hoped and never se r ious ly cha l langed w ool .

1 .7 Syn thet i c F ibres

The c lass ic researches o f W al lace Hum e C aro thers on po ly m er syn thes is s ta r ted

in the Du Po nt (USA ) in 1928 and bu lk sca le p roduct ion o f ny lon 6 and ny lon 6 ,6

s ta r ted in 1939. J .R.W hinf ie ld and J .T .Dickson d iscovered po lyes te r in 1941 and

w a s c o m m e r c i a l l y m a n u f a c t u r e d b y 1 9 5 4 . Y a m t e x tu r is i ng a n d s p in d r a w y a m sp r o d u ced a t su p e r h ig h sp eed s h av e f u r th e r in c r ea se th e p o p u la r i ty o f sy n th e t i c

f ib res [75, 76] . Po lys te r f ib re accounts fo r more than 50% of the to ta l syn the t ic

f ib re p ro duct ion .

1.7.1 Polyes ter

Ter ep h th a l i c ac id o r d im e th y l t e r ep h th a la t e an d e th y len e g ly co l p o ly m er i se b y

c o n d e n s a t i o n r e a c t i o n to f o r m t h e p o l y e s t e r p o l y m e r (F i g . 1 -2 1 ). A f t e r

H O O C - - C O O H + n H O - C H 2 - C H 2 - O H , -H~O

tereph tha l ic ac id e thy lene g lyco l

OH(H2)2-o-o < ) OOHPolyes te r f ib re

Figure 1 -21 . Ch em ica l reac t ions in po lye s te r fo rmat ion .

n = 80 - 100

poly m er isa t ion they a re ex t ruded in the fo rm o f r ibbon , then cu t in to ch ips. The

ch ips a re d r ied and conveyed to a hopper , f rom which they a re fed to the mel t -

sp inn ing tank (F ig . 1 -22). The ho t so lu t ion i s fed th rough the sp innere t te and so-



2 8 K i n d s o f F i b re s

l id i f ies in to f ib re fo rm upon con tac t wi th a i r. I t i s s t re tched whi le ho t to ob ta in

s t rength.P o l y es t e r i s ma d e u p o f fu l ly ex t en d ed p l an e r ch a i n s an d r ep ea t u n i t a l o n g t h e

cha in is 10.75.A. and the su cce ss ive es ter gro ups are essent ial ly in the t rans co nfigu -

r a t i o n o f each o t h e r (Fi g . 1 -2 3 ). T h e p o l y m er is h e l d t o g e th e r ma i n l y b y V an d e r

. . . . dimethyl erephthalateorI _ ~ ~ terephthalicacid

ethylene glycolor otherdihydric alcoholmethanol

[ ~ . . t ~ . .. --~~wUy......:.

/ spinnerette

cutter, cherperand otherprocessing

F i g u re 1 -2 2 . F lo w d i ag ram o f p o l y es t e r

m an u fac t u r i n g p ro ces s .

F igure 1 -23 . S t ruc tu re o f po ly e thy le ne

terephthalate .

W aa l s ' f o rce s an d t o a l e s s e r ex t en t s o me w e ak h y d ro g en b o n d s. T h e p o l y m er

sys te m i s es t im ated to be about 65 to 85% crys ta l l ine .

The p hys ic a l p roper t i es o f po lye s te r is g iven in Tab le 1 .16. Th i s f ib re has h igh

t en s i le s t ren g t h , l o w m o i s t u re r eg a in , h i g h i n i t ia l mo d u l u s an d g o o d c r ea s e r eco v -

ery . S t rong caus t i c a lka l i es a t h igh t empera tu res hydro lyse and degrade the f ib re

and con cen t ra ted su lphu r ic ac id d i s in tegra tes the f ib re . Po lyes te r d i s so lves in ho t

m-creso l , t r i - f luoro ace t i c ac id and o-ch lorophenol .

T h e ch em i ca l mo d i f ica t i o n s o f p o l y es t e r is m a i n l y i n ten d ed t o o v e rco m e s o m e

o f t h e i n h e ren t d r aw b ack s o f th e f ib r e s u ch a s l o w d y eab i l it y , lo w m o i s t u re r eg a i n ,

s t a ti c accu m ula t ion , so i l ing tenden cy , p i l l ing p roper ty and f l amm abi l i ty . Dev elop-



Kinds of Fibres 29

T A B L E 1 . 1 6

Phys i ca l P roper t i e s o f Po lyes t e rProper ty Range

Ten aci ty, g/den 2.5-6.0

Elong at ion , % 12-15

Elas t ic recove ry , %

Ave rage s t if fness , g /den

Speci f ic gravi ty

Mois ture regain (s tandard

condi t ion) , %

90-96 a t 2% extens ion

8-25

1 . 3 8

0.4

men t s o f bo th hom o - and co -po lyes t e r s have con t inued and man y mo d i f i ed po ly -

es te r s have appeared wi th improv ed p roper ti e s . The repea t i ng un i ts o f some o f t he

m o d i f i e d p o l y e s t e r a r e g i v e n i n F i g . 1 - 2 4 . K o d e l I I i s b a s e d o n 1 , 4 -

d imethylcyclohexane terephthala te and g ive increased s tab i l i ty to hydrolys i s . A-

Te l l is po lye thy l eneox yben zoa t e (PEB) and has a s il k l ike hand le and d rape , good

wrinkle res is tance and easy care proper ties. T he se l f po lym er ofp oly (p ivalo lactone)

has bet ter res i s tance to hyd rolys i s and a muc h h igher m el t ing poin t than the or ig inal

a l iphat ic polyes ter . Polybuty len e terephthala te (PBT) i s a carr ier free dyeable poly-

es t er wi th low er g las s - t rans i t ion t em pera tu re (Tg) . Vyc ron (US A) i s a m od i f i ed

polyes ter where terephthal ic ac id i s par t ly reduced by i sophthal ic ac id to open up

the com pac t s tructure . Sulphon ic ac id group is in t roduced ad di t ional ly in to the

i sophthal ic ac id to dye w i th bas ic dye (CDPE T). S imi lar ly anionic dyeab le polyes-t e r is a lso i n t roduced con t a in ing n i trogenous com pounds (po lyamines ) w h ich o f fe r

bas ic grou p as s it es for the adsorpt ion o f ac id dyes . Th erm otropic ' liquid crys ta l'

ph i l o soph y has deve loped a fu ll y a romat i c po lyes t e r s l i ke po lya l l y l a te f ib res wi th

very h igh t ens il e mo du lus (o f t he o rde r o f 100 Gpa). The c ros s - sec t i on o f t he

regu lar polye s ter i s round, of dacron (Du Poin t ) is tr i lobal , of For te l and Enc ron i s

T-shap e, ofT rev i ra (Hoechs t ) i s penta lobal an d of Ko del is t r il a tera l . Cha nges that

occur the cross -sect ion produce f ibres wi th d i f ferent hand and appearance.

1 . 7 . 2 Ny lon

The m os t popu la r o f t he a li pha ti c po lyam ides a re ny lon 6 ,6 and ny lon 6 . N y lon



30 Kinds of Fibres

Rep eating unit Fibre

o o 1~-O ~ - > I'_C_O_CH2_ CH20 Kodel I IE a s t m a n K o d a k )

nO H H

~ O - ~ - < > O - C - ~ @ _ A -T e l l ( J a pa n)

f i H nH CH 3

O - C - C - CI I I IH C U 3 0

poly (pivalolactone)

O O

5o < > _

+ O - - ~ ./ / ,I - ~ - O - C H 2 - C H 2 +n

~ O ~ HO O-

n

polybutylene

terephthalate

Cationic dyeable

polyester (CDPET)

Anionic dyeable

polyester

Figure 1-24. Repeating units o f some m odified polyester [77].

6 is the polymerisation product made form s - caprolactum and nylon 6,6 is pro-

duced by po lycondensa t ion f rom ad ip ic ac id and hexamethy lene d iamine

(Fig. 1-25 ). Th e 6,6 designation simp ly implies that each of the two raw m aterials

. . . . I ~ I C H 2 - C H 2 - N H

n C H 2 I ~ - - ~ C O ( C H 2 ) s - N H

~ C H 2 - C H 2 - C = O n

g-caprolactum nylon 6 n = 200 +

n HOOC-(CH2)4--COOH + nH2N-(CH2)6-NH2--, [--CO(CH2)4-CO-NH(CH2)6NH--~

adipic acid hexam ethylene nylon 6, 6

diamine n = 5 0 - 80+

Figure 1-25. Ch em ical reactions in nylon 6 and 6, 6 m anufacture.



Kinds of Fibres 31

contains 6 carbon atoms. Fig. 1-26 gives the flow chart show ing steps in the manu-

h e x a m e t h y l e n eF d i a m i n e

P ~ v m e r i z a t i ~ [ ~ ~ t ] ~ i ; " : [r e a c t ,O r [ ~ ; g ? ; : l ~ ) f V ! p re s s u re

w a t e r ~ I ! ~ ~ 1 ~ ; ; " : ......" ; " l / ~ A

: / " ~ . , , ' r

0rat0r~'L J I ~ ~ i t c h i ; p e r -~ " " :) i. i:. ~ c h i p p e r b b i n ,

e v a p : .. ~ ; ; ' .; . " . . " : / c o l d ~ r a w i n g ,

L~ vi!erl~ ~ r l ? i _ _ 1 ~// andtwisting

Figure 1-26. Flowchart showing steps in the m anufacture o f nylon 6, 6.

facture of nylon 6,6 . Specific amounts of the tw o chemicals are combined in

solution to form nylon salt. The salt is purified, polymerised, extruded in ribbonform and chipped into small flakes or pellets. The polym er is then melted and

extrud ed through a spinnerette into cool air, where the filame nts are formed. The

filamen ts are then stretched or cold drawn to develop desired properties. Ny lon

staple is obtained by crimping filament tow and then cutting into short uniform

lengths.

The estimated po lym er length of nylon varies from 90 to 140 nm with polym er

thickness o f 0.3 nm. The am ide linkage (-CO-N H-) ows its polarity to the slightly

negative charge on its hydrogen atom, that is imino hydrogen. Man y other nylons

are synthe sised (Fig. 1-27 ), am ong st them 6, 10, 7, 11 etc. are marke ted to som e

extent. Ny lon filame nts are sm ooth and shiny. W hen view ed in cross-section,

nylo n is usua lly perfe ctly round. The y are highly resistance to alkalies and rela-

tively less resistance to acids. The noteble feature of various nylon s is their mois-

ture sorption and melting point (Table 1.17). The photochemical behaviour of

nylon is less favourable and the fibre turns yellow on heat and oxidising agent

treatmen ts. Apart from these textured nylons are very popular.The mo dified nylons can take several forms 9 hanging cross-section o f shape



32 Kinds o f F ibres

Re pea t un i t F ib re

H H

[ - ~ ' - - ~ ) ,0 - ,~ - ]nH H H

I I I- C - C - C - N -

I i UH H O

[ ( " ) 13 0 n

H H

H H 1

O O

Nylon 11

Ny lo n 3

Ny lo n 4

Ny lo n 7

Nylon 12

Nylon 6, 10

Figure 1 -27 . Re pea t un i t s o f var ious ny lons .

T A B L E 1 . 1 7

Mo is tu re So r p t io n o f Va r io u s Ny lo n s

Fibre M ois tu re sorp t ion

(%) at 65% r .h .at 20~

Sp. gr. _ M . Pt. (~

N ylon 6 3 .5 -5 .0

N ylon 6 ,6 3 .8-4 .5

N ylo n 11 1 .18

N y lo n 4 Hig h e r th an co t to n

Ny lo n 6 ,1 0 2 .6

1.14 210

1.14 250

1.04 189

2 1 4

and chan ging the physica l and ch em ica l p roper t ies to improve dy eab i l i ty , hand le ,

tenac i ty , hea t s tab i l i ty e tc . The repea t un i t s o f some o f the mod if ied ny lon s a re



Kinds of Fibres 33

given in Fig. 1-28. Both nylon 6T and Nom ex have very high thermal resistance.

Repeat unit Fibre

- H N C H 2 ) 6 N H C O - @ C O -

H H

( - l ~ - ( ) l ( I - ~ - ~ ~ - )n

Nylon 6T

Nomex, Kevlar (Du Pont)

H H

PBI (Celanese Corpn.)

. u i n a , . u ' o n t

0

II

0

0II

II

0

Polyimide

OII

" )~ ,- C - - 1~ - n

II

O

Kermel (Rohne-Poulene)

0 O ~ 0

(~ ~,_~ ~-~ ~ ~~~ )~) X-500 (Monsanto)

Figure 1-28. Repeat units of some m odified nylons [78].

Ny lon 6T mel ts a t 370~ Nom ex is p rac t ica l ly f lameproof . Kevla r , po ly

(p-phynyleneterephthalam ide) represents a break-through in high m odu lus arom aticpolyam ide fibre and ma inly used as reinforcem ent tyres, conveyers belt etc., PBI is



34 Kind s o f F ib r e s

o b t a i n e d b y r e a c t i n g d i a m i n o b e n z i d i n e a n d d i p h e n y l i s o p h t h a la t e a n d i s u s e d a s a n

a l t e r na te to a sbe s tos in h igh t e m pe r a tu r e f i lt r at ion a nd the r m a l p r o te c t ion c lo th ing .I ts m o i s tu r e r e ga in i s h igh a t 14 .4%, wh ic h pe r m i t s h igh de g r e e o f c om f or t [79 ].

Q u ina , w i th a t r il oba l c ros s s e c tion , is a po lyc onde nsa te o f d ia m inod iph e ny lm e tha ne

a nd de c a ne d ic a r boxy l i c a c id . I t i s d i s t ingu i she d by i ts s i lk - l ike ha nd le a nd r e -

ga r de d a s syn the t ic subs t i tu te f o r pu r e s i lk . Ke r m e l is a po ly a m ide - im ide f ib r e

m a de f r om e i the r t r im i l l i t i c a nhydr ide c h lo r ide a nd a d i a m ine o r a d i i soc ya na te .

The s e po ly m e r s ha v e r e a sona b le the r m a l s t ab i li ty , ve r y r e s il i e n t and ha ve e xc e l l e n t

f l a m e - r e s i s t a nc e . The M ons a n to ' s X- 50 0 c l a s s o f f ib r e , o f w h ic h tha t p r e pa r e d

f r o m p o l y a m i d e - h y d r a z i d e i s ty p i c al . D e v e l o p m e n t s i n m e l t - s p i n n i n g h a v e l e d t o

f i l a m e n t s w i th nove l c r os s - se c t ions o r c on ta in ing c a v i t ie s to ob ta in im pr ove d p r op -

e r t ie s , such as inc reased cover , a c r i sp , s i lk- l ike , f i rm hand, reduced p i l l ing , in-

c r e a se d bu lk , sp a r k le e ff e c t s a nd he igh te ne d r e s i s t a nc e to so il . Ge ne r a l ly , no r m a l

ny lo n ha s a r oun de d c r os s - se c t ion a nd Q u ina ha s t r il oba l c r os s - se c t ion . C a d on

( M o nsa n to ) ha s a roun de d squa r e c r os s - se c t ion wi th f ou r c a v i t ie s [8 0] .

1 .7 .3 A c r y l i c f i b r e s

P o l y a c r y l o n i t i l e ( P A N ) i s a l o n g c h a i n p o l y m e r c o n t a i n i n g a c r y l o n i t r i l e[ - C Hz - C H ( C N) ] a s r e pe a t ing un i t i n the po lym e r ic c ha in a nd a r e f o r m e d by a dd i -

t ion polym er isa t ion . Acryl ic f ibre conta ins 15% or le ss co polym er . The mod acryl ic

f ib re s a r e c om pr i se d o f l e ss tha n 8 5% bu t a t l e a s t 35% by w e igh t o f a c r y lon i t ri l e .

The c om onom e r s a r e a dde d to inc r e a se the po lym e r the r m op la s t i c i ty , so lub i l i t y ,

dyeabi l i ty , mois ture rega in , e tc .

T h u s , t h e m o l e c u l a r s t ru c t u re o f c o p o l y m e r o f a c ry l o n it ri le a n d c o m o n o m e r i s

r e p r e s e n t e d a s

x

C N y n

n = 150 to 200 uni ts

w h e r e m a n d p a re n u m b e r o f m o n o m e r a n d c o m o n o m e r u n i ts r e s p e c ti v e l y in th e

po lym e r c ha in , n i s t he de g r e e o f po lym e r i sa t ion a nd x a nd y a re the subs t i tu t e d

gr oup s o f the c om ono m e r . I n ge ne ra l , t he r e ar e th r e e s ta ge s fo r the p r od uc t ion o f

ac ry l ic f ibres , i .e ., po lym er isa t ion , dop e prepara t ion and sp inning (Fig . 1-29). Acry-lon i t r il e i s po ly m e r i se d e i the r by the susp e ns ion sy s t e m in wh ic h w a te r is u se d o r






T A B L E 1 . 1 8

M odi f i c a t ion o f Ac r y l i c F ib r e s [8 1]M o d i f i c a t i o n M e a n s o f M o di f i c a t ion F ib r e ob ta ine d

C h e m i c a l m o d i f ic a t io n B y c o m o n o m e r s EnhanJzed d isso lu t ion and

dye ing , F la m e r e s i s t a nc e ,

A n t i s t a t i c , I m p r o v e d h y -

drophi lic i ty , Dy e ing s imul-

taneous ly w i th ac id and ba -

sic colours.

Phys ic a l m od i f i c a t ion

B y p o l y m e r m i x t u r e

I nc o r por a t ion o f

addi t ives

A t p o l y m e r i s a ti o n

s tage , dope prepara -

t ion a nd sp inn ing

condi t ion .

G r a f t p o l y m e r i s a t i o n ,

Bicom ponen t f ibres, F ibres

f ro m p o l y m e r m i x t u re .

E n h a n c e d w h i t e n e s s a n d

therm al s tabil i ty, Flam e re-

ta rdant, A nt i - so i l ing , Ant i -sta t ic , Anti-pi l l ing.

Hi-bulk f ibres , Hol low f i -

b r e s , C h a n g e o f s u r f a c e

s t r uc tu r e , Ex t r e m e de n ie r

fibre.

350~ I t has g lass- t ran s i t ion be tw een 85 and 100~ wh ich appears to va ry wi thm olec ula r w e ight . I t has poor res is tance to s t rong ac ids , a lka l ie s and to a few pola r

organ ic so lven ts . I t s r e s is tance to sunl ight i s good.

The m o da c r y l i c f ib r e s ha ve s im i l a r p r ope r t ie s to those o f a cr y l i cs a nd a r e f la m e

res is ta n t . .M ost ly th is fibre is based on a 60 /40 or 50 /50 copo lym er of ac ry loni t r i le

wi th v iny l id ine c h lo r ide ( C H 2 = C C 12) toge the r w i th sm a l l p r op or t ion o f t e r na r y

m o n o m e r to im p r o v e i o n i c d y e a b i l i ty o r h y d r o p h i l ic i t y . T h e b e t te r k n o w n

m oda cryl ic f ibres have a r ibbon -shape d or pea -nu t shaped c ross- sec t ion . One prob-

lem en cou nte red wi th mo dacry l ic f ibre is loss of lus t re a t the boi l [83 , 84]. Th is

f ibre i s used for appare l , home furn ish ing , wigs e tc .




1.7.40lefin fibres

Polye thy le ne a nd po lyp r opy le ne f ib r e s a r e bo th use d a s f ib r e - f o r m ing f o r t e x -

t il e pu r pose s . The y a r e w id e ly use d in indus t r ia l f a b r ic s . The se tw o f ib r e s c an be

bond e d in to non - wo ve n f a b ri c f o r m a nd use d a s the ba se f o r tu f t e d ca r pe t ing . O le -

f in f ibres a re re la t ive ly low in cos t, but both the f ibres have low m el t ing p oin ts , low

gla s s - t ra ns i t ion t e m pe r a tu r e s a nd poor dy e a b i l it y .

The po lye thy le ne f ib r e i s p r oduc e d by e i the r h igh p r e s su r e po lym e r i sa t ion o f

e thy le ne w i th a pe r ox ide - c a ta lyse d p r oc e ss o r low p r e s su r e po lym e r i sa t ion o f e th -

y le ne us ing ne w c a ta lys t s sys te m s . The m ole c u la r s t ruc tu r e o f po ly e thy le n e i s a

l ine a r po lym e r o f e thy le ne un i t s w i th r e pe a t un i t o f

- ~ - C -

n n = c .550.

Or id ina r y p o lye thy le ne o f m o le c u la r w e igh t c a 104 is d r a wn up to t e n t im e s in

l e ng th bu t t he ge l - sp inn ing m e thod p r oduc e s the f ib r e tha t c a n be d r a w n ove r th i r ty

t im e s a nd c a n ye i ld a You ng ' s m od u lus o f 9 0 GPa . Fa br i c s m a de f r om th i s m a te -

r i al posse s s h igh im pa c t s t r e ng th , h igh we a the r r e s i s t a nc e a nd c a n be use d f o r m a k -

ing bul le t pro of c lo th ing , pro tec t ive w ear , f i lte r , sa i l ing c lo th , pa rach utes e tc.

The f i l a m e n t s o f po lyp r opy le ne f ib r e ar e p r oduc e d f r om p r opy le ne us ing spe -

c i al c a ta lys t s. The po ly m e r i sa t ion p r oc e ss invo lve d i s a dd i t ion , a s the doub le bond

i s b r ok e n in the p r opy le ne m ole c u le , t he m on om e r o r s ing le m ole c u le s jo in o r a dd

toge the r . The f i l a m e n t s a r e p r odu c e d by the m e l t - sp inn ing p r oc e ss in a s im i l a r

m a nn e r to po lye s t e r . The r e pe a t un i t o f po lyp r opy le n e i s

H

(- H- C = ~ - H- _ L

U H 3 n n = c. 1800.

W h e n t h e p r o p y l e n e ( m o n o m e r ) p o l y m e r i s e s , t h e p e n d e n t CH 3 can l ie in e i ther

d i r e c t i o n . T h e r a n d o m l y d i s p o s e d CH 3 gr oup ( a t a c t i c f o r m ) doe s no t f o r m good

f ib r e . I n the i so t a ct i c f o r m the m e thy l g r oups a r e on the sa m e s ide o f the po lym e r

ba c kbone , bu t i n synd io ta c t i c a r r a nge m e n t the m e thy l g r oups l a y a t t e r na te ly on

e i the r s ide o f the po ly m e r c ha in ( F ig . 1 - 30 ). To p r oduc e th i s fo r m o f po lyp r opy-lene , spec ia l ca ta ly s ts a re used .




( i ) I S O T A C T I C P O L Y P R O P Y L E N E

c , . 3 c , . , c , . , ~ , H , ~ , . ,--CH~ C H e r t = C H C ~ C H C ~ C H C ) ~ C H C H z - - -

( ; { ) S Y N O I O T A C T IC P O L Y P R O P Y L E N E

r r c ~I j

--cM 2 CHCH1 CHCH CEC Il z ~:HCH ~:HcH;;--

CN3 ri i i ) A T A CT IC P O L Y P R O P Y L E N E

c N CiHI

c . ) c . ] r 3

Figur e 1 - 30 . S te r e os t r uc tu r e s o f po lyp r opy le ne c ha in .

Un m o di f i e d po lyp r opy le ne i s h igh ly c r ys ta l li ne . The a bse nc e o f in t e r c ha in hy -d r oge n bon d ing e f f e c t ive ly r e su l t s i n the f ib r e be ing a pe r m a ne n t ly swo l l e n s ta te .

S ta b i l i s a tion o f p o lyp r opy le ne to hea t , ox ida t ion a nd l ight , pa r t i c u la r ly to u lt r a v io -

le t r ad ia t ion i s ex t rem ely im por tan t and the pa tent l i te ra ture on th is subjec t i s ex ten-

s ive . The u nm odi f i e d po lyp r op y le ne f ib r e i s d i f fi c u l t t o dye a nd e x te ns ive a t -

t e m pts ha ve be e n m a de to m od i f y the f ib r e s t r uc tu r e by the in t r oduc t ion o f dye -

r e c e p t ive s i te s [8 5 - 89 ] . M o is tu r e a bso r p t ion o f po lyp r o py le ne i s v i r tua l ly ze r o .

The f ib re ha s h igh t e ns il e s t r e ng th a nd good r e s i s ta nc e to a c ids a nd a lka l ie s . W i th

a spec i f ic g ravi ty o f abou t 0 .9 , the f ibre i s the l ightes t fibre group. The m el t ing

po in t o f p o lyp r op y le n e i s 176 ~ Po lyo le f in fib re s r e se m b le g l a s s r od in long i tud i -

na l a nd c r os s - se c t iona l v i e w . The m on of i l a m e n t po lyp r op y le ne i s m a in ly use d in

ou tdoo r furn i ture we bbing , in ca r sea t covers , sw im m ing pool covers , f i l te r f abr ics ,

in the rope s a nd c o r da ge f i eld s e tc . The m ul t i f i l a m e n t ya m s c a n be use d a s b l a n -

ke ts , uphols te ry fabr ics , swea te r s , ca rpe ts , p i le fabr ics , s tockings and can p lay a

m a jo r r o l e in non- w ove n f a b ri c s.

1 .8 M i s c e l l a n e o u s S y n t h e t i c F i b r e s

The r e a r e m a ny o the r syn the t i c f ib r e s ha ve be e n de ve lope d ove r the ye a r s in




m a ny c oun t r i e s , bu t on ly a f e w o f the m a r e use d f o r a ppa r e l a s we l l a s c om m e r c ia l

a nd indus t r ia l u se . Th oug h the se f ib re s a re no t w ide ly use d bu t the sc i e nc e a ndte c hno logy o f the se f ib re s a r e b r i e f ly d i sc usse d f r om the a c a de m ic po in t o f v i e w .

1 . 8 . 1 C h l o r o f i b r e s

Po ly ( v iny l c h lo r ide ) f ib re u se d f o r t e x t i le s i s m a nuf a c tu r e d f r om a c e ty le ne a nd

hyd r oge n c h lo r ide wh ic h i s d i s so lve d in m ix tu r e s o f c a r bon d i su lph ide a nd a c e tone

f o r d r y - sp in n ing o f no r m a l v iny l c h lo r ide (PVC ) hom opo lym e r . The f ib re s a r e

c opo lym e r o f v iny lc h lo r ide / v iny le d ine c h lo r ide a nd v iny l c ya n ide o r v iny l a c -

e ta te . Th e f ibre is s t re tched to va ry ing deg rees as it leaves the sp inn ing je t to g ive

d i f f e re n t t ype s o f fi l a m e n t s . The r e pe a t un i t s o f som e o f the c h lo r o f ib r e s a r e show n

in F ig . 1 - 31 . The w a te r a bso r p t ion o f the se f ib r e s ar e e x t r e m e ly low, so f t e n ing

F ib r e R e p e a t un i t

Dyn e l |

( Un ion c a r b ide )

S a r a n |

( D o w C h e m . C o r p n . )

Viny on |

(Avtex Fib res Inc . )

L ~1 ) x / C N ] y J n

x = 60%, y - 40%

C1

C1 C1 ~y~ n

x > 8 0 %, y < 20 %

' C1 /x O~ CH ~y n

O

x = 85%, y < 15%

Figur e 1 -31 . R e pe a t un i t s o f som e c h lo r o f ib r e s .

t e m p e r a tu r e i s l ow wi th c ons ide r a b le sh r inka ge a t 7 0~ a nd ha ve poor dye a b i l i t y a t

m ode r a t e t e m pe r a tu r e s . The se f ib re s a r e m a in ly use d in f il t er c lo ths , f l y ing su i ts

( in wh ic h the i r p r ope r ty o f non - f l a m m a bi l i t y i s a n a s se t ), c u r t a ins ( owing to the i r

r e s i s t a nc e to de g r a da t ion o f l i gh t ) a nd f i sh ing ne t s ( owing to the i r r e s i s t a nc e to

wa te r ). The se f ib re s ha ve r e gu la r r ound , dog bone o r dum be l l sha pe d c r os s - se c t ion

a nd t r a nspa r e n t , e ve n a nd sm oo th . The y a r e h igh ly lu s t r ous a nd s i lky in ha nd .

1.8 .2 Poly (v inyl a lcohol ) f ibres

Polyv iny l a l c oho l i s m a nuf a c tu r e d ind i r e c t ly by the hydr o lys i s o f po ly ( v iny l




ace ta te ). Th e polyvin yl a lcohol i s so lu t ion-spu n to form the f ibres and hot s t re tched

a t 200~ As ext ruded, the f ibre i s w a te r so luble and m ust be t rea ted w i th form al-de hy de to m a ke the m inso lub le . The r e pe a t un i t o f V ina l | i s

C H 2 - , HO H ] x \ C ] y n

IH C R

I0

x > 5 0 % , x + y > 8 5 % , R = - H ,

The c r ys t a l li ne po ly ( v iny l a l c oho l) ha s a k inke d c ha in w i th th r e e m on om e r pe r

repea t [90 ] . This f ibre poss esses g ood res is tance to ac ids , a lka l ie s and m ost or -

ganic so lvents excep t formal in , phen ol , c resol and formic ac id abov e 60~ I t can

be b le nde d wi th c e l lu los i c f ib re s a nd dye d . V ina l doe s no t suppor t c om b us t ion ; i t

so f t e ns a t 20 0 ~ a nd m e l t s a t 220 ~ Al l i e d I nc. o f US A ha s de ve lope d h igh

m o du lus h igh t e na c i ty supe r h igh m ole c u la r we igh t PVA f ib re by ge l - sp inn ing a nd

the p r ope r t ie s o f PVA a r e s im i l a r to those o f Ar a m id f ib re s . Th i s f ib re i s e m ploye d

in pro te c t ive appare l - ra in co a ts , jacke ts , h a ts , umbre l la s , su i t ing and l in ing fabr ics ,socks and g loves . Ind us t r ia l uses inc lud e f i sh ing ne ts , f i l te r f abr ics , tyre cord , ta r -

paul ins and br is t le s .

1 .8 .3 E l a s t o m e r i c f i b re s

Spandex i s the gener ic te rm appl icable to a l l e la s tomer ic f ibres in which the

f ib r e f o r m ing subs ta nc e c ons i s ts o f at l e a s t 85% of a s e gm e n te d po lyu r e tha ne . The

f i rs t e l a s tom e r ic f ib r e , L yc r a wa s de ve lope d by Du Pon t a r ound 19 58 . The f ib r e s

a r e c ha r a c te r i s e d by e x t r e m e ly h igh e longa t ion a nd ou t s t a nd ing e l a s t i c r e c ove r y .

The c ha in m o le c u le s a re m a de up o f ha rd se gm e n t s - c r ys ta l li ne , h igh m e l t ing po ly -

u r e tha ne - a nd o f so ft s e gm e n t s - low m e l t ing , a m or pho us po lye s t e r o r po lye the r s .

Hyd r oge n bonds a r e m a in ly f o r m e d be twe e n the ha r d se gm e n t s [9 1 .9 2 ] . E la s t ic

ha r d f ib r e s m a y be p r e pa r e d f r om po lyp r opy le ne , po ly ( 3 - m e thy lbu t - 1 - e ne ) , po ly

( oxyr ne thy le ne ) [93 ] a nd po ly ( i sobu te ne ox ide ) [94 ] a nd l a r ge ly ba se d on 4 , 4 ' -

m e t h y l e n e b i s ( 4 - p h e n y l i s o c y a n a t e ) , u t i l i s i n g d i a m i n e o r g l y c o l e x t e n d e r s .

F ig . 1 - 32 p r ov ide s a s im p l i f ie d ou t l ine o f c om m e r c ia l c he m is t ri e s a nd F ig . 1 -33

show s a n ove r v ie w o f d r y - sp inn ing p r oc e ss o f S pa nde x .S pa n de x f ib re s ha ve dog bone to r ounde r c r os s - se c tion a nd t e nd to be l a rge r in




P r e p o l y m e r r e a c t io n

c , , c , , , , , , , , , . o o . o . , . O . , , , . O . , . c . 0

l

0 = C = N J~ O~ I~ - I ' - N = C = 0

C h a i n e x t e n s i o n r e a c t i o n

0 = C = N J~ ~ r ~ - -~ - N = C = 0+

ObmiM

!

[)~lutton

F i g u r e 1 - 3 2 . P r e p o l y m e r r e a c t i o n ,

c ha i n e x t e ns i on r e a c t i on .

' ~ - - ] ,I I .

, . _ - ~ | : "

Chain-xtensior

S~n~r~Cell

,I

Coele,cwce .- -

Hot Gas

Solvent

F i n i s h , /

w ~ n ~ u p l

F i g u r e 1 - 3 3 . D r y - s p i n n i n g p r o c e s s o f

S pa nde x .

d i a m e t e r . S pa nde x h a ve a de ns i t y o f 1 .0 -1 . 2g / c m 3, m o i s t u r e a bs o rp t i on i s 0 .3 -

3 % , w h i l e e l o n g a t i o n a t b r e a k a m o u n t s 4 5 0 - 9 0 0 % a n d 9 5 % e l as ti c r e c o v e r y f r o m

20 0 % e x t e ns i on . Th i s fi b r e ha s g l a s s - t r a ns i ti on t e mp e ra t u r e be l ow 0 ~ s o t ha t s o f t

c o m p o n e n t s h a v e a c o n s id e r a b le f r ee d o m o f m o v e m e n t a t r o o m t e m p e r a tu r e a n d

abov e . E la s tom er ic f ibres a re res i s t an t to d i lu te and cold ac ids , and a l so to a lka l i es .

T h e y c a n b e i r o n e d sa f e ly a t t e m p e r a t u r e s b e l o w 1 50 ~ T h e y a r e u s e d fo r s u c h

p u r p o s e s a s s w i m w e a r , f o u n d a t io n g a r m e n t s , s p o r ts w e a r , h o s i e r y , b r a s , s o c k t o p s

a nd me d i c a l p rod uc t s r e qu i r i ng e l a s ti c it y .

1 . 8 . 4 C a r b o n f i b r e s

C a r b o n f i b r es a re m a n u f a c t u r e d f r o m ra y o n a n d p o ly a c r y l o n i tr i le . C a r b o n f i -

b r e s c a n be he a t e d up t o 1500 ~ a nd c on t a i ns up t o 9 5% of e l e m e n t a l c a rbon .

G r a p h i t e f ib r e s c a n b e h e a t e d a b o v e 2 5 00 ~ w i t h 99 % c a r b o n . T h e f o r m a t i o n o f

c a rbon f i b r e s f rom po l ya c ry l on i t r i l e i s ou t l i ne d i n F ig . 1 -34 . C a rbon f i b r es a r e u s e d

in the ae rospa ce indus t ry , in com presso r b lade to j e t engines , he l i copte r ro tor - b lades ,

a i r c r a f t f u s e l a ge s t ruc t u r e s , go l f - c l ub s ha f t s , c ros s -bow s fo r a r c he ry a nd i n h i gh

s pe e d r e c i p roc a t i ng pa r t s i n l oom.



42 Kinds of Fibres

C N C NI I

. . , , /CH 2 CH 2

c a 2 CH 2 /

I IC N C N

C N C N

~ H ~C H C H C Hoxidation > (~ ++ 0 2

-2H20CH CH (~H

~ c H ~ c ~ / ~I I

C N C N

I I

c ~cI

Figure 1-34 . Form at ion of PAN based carbon f ibres [95].

1 . 8 . 5 P T O f i b r e s ( E n k a t h e r m )

Enk atherm , a high temp erature flam e-pro of fibre is based on poly (terephthaloyl

oxal ic-b is-amidrazo ne) (PTO). This f ibre is produced by wet -sp inning and then

drawn [96,97] . The form ula of PTO and chela ted forms of PTO is shown in

Fig. 1-35.

H H

_NI_ N . / N _ N I \

c -c c-// \~-c-

. . $ 8 8

C - C-... : ,,/ M e . , . . O O

N / N H 2

~ N = C /

Nc=\H 2 N , , , , / N - C - ~ C

O ~ O / M e , , / / O O

- C - -( / ~ - - C N \ N H 2

\ N = C <

Figure 1-35 . Form ula of repeat uni t of PTO f ibre, showing possib le chela ted form.

1 . 8 . 6 O t h e r s y n t h e t i c f i b r e sM any other synthet ic f ibres are found in the l i te ra ture , the t rade nam es of som e

of them are Novoloid , PBI, Polycarbonate , Alginate , Flurocarbon (Teflon) , ra in-



Kinds o f F ibres 43

era l fib res l ike g lass , ce ramic and asbes tos f ib res , b icom pon ent and b icon st i tuen t

fibres etc.Novolo id i s the des igna t ion ass igned fo r a c lass o f f lame re ta rdan t f ib re made

f r o m c r o ss - lin k ed p h en o l f o r m a ld eh y d e p o ly m er s . P o ly b en z im id azo le , o r P BI is

non f lam m able , co m for tab le , f lex ib le and used in appare l fo r space and fo r d rogue

chutes and und ersu i t fo r as t ronau ts . Po lycarbo nate f ib res a re linear po lye s te r s o f

a l ipha t ic o r a rom at ic d ihydrox y comp ound s wi th carbonic ac id [98] and has exce l -

len t res is tance to hea t and wea ther ing . The raw m ater ia ls fo r g lass f ib re a re p r ima-

r i ly s il ica , sand and l ime s tone wi th modif ie r s l ike a lum in ium hyd rox ide , so d ium

carbonate , and borax [99] . M ajor uses o f the f ib re a re in w indo w cur ta ins , tab le -

c lo ths , i ron ing board covers , lampsh ades sc reens e tc . The p roduc t ion o f e lec t r i-

cal ly condu ctive f ibres [100 - 102] and meta l l ised f ibres [103,104] are reported. In

per fum ed f ib res (M is tub ish i Rayon) the essence i s cap tured in four peda l - like cav i -

t ies a r ranged rad ia l ly in a ho l low f ib re . The essence i s g radua l ly re leased th roug h

the f ib re c ross-sec t ion p roduces the re f resh ing e f fec t typ ica l o f deep fo res ts and

induces good s leep . Apa r t f rom these , tex t i le f ib res fo r m edica l app l ica t ions , a r t i-

f ic ia l sk in , f ib res p roduced by bac te r ias l ike bac te r ia l ce l lu lose , po lyes te r andBiop las t ics and carbon f ib res f rom w ood , op t ica l fib res and new po ly te t ram ethy lene

e t h e r g l y c o l ( P T M E G ) f r o m t e t r a h y d r o f u r a n ( T H F ) f o r e l a s t o m e r i c m a t e r i a l

(Tetrathe ne by D u Pont) e tc. are the recen t advance s in the f ie ld of f ibre scienc e and

technology .

Bico m p o n e n t f ib r e s a re sy n th e t ic f ib re s co m p o sed o f two f i r m ly b u t sep a r a t e ly

co m b in ed p o ly m er s o f d if f e ren t ch em ica l an d p h y s ica l s tr u c tu r e s. Th e s t ru c tu re o f

the bicom pon ent dep ends on the shape o f the spinneret te or ifice (side-by-side, sheath

core , m at r ix - f ib r i l and m ul t i - f ib r i l la ry) and the type o f sp inn ing metho d . Due to

the s t ruc tu ra l d i ffe rences , the two co m pon ents sh r ink d i f fe ren t ly on hea t t rea tmen t

and fo rm cr imp and grea te r bu lk in the f ib re . The f i r s t fu l ly syn the t ic b icom pon ent

w as an acry l ic (Saye l le , Or lon 21) . The use o f shea th-core f ib res com pose d of

ny lon 6 ,6 and ny lon 6 (Heterof il , ICI ) fo r f loor cover ings i s descr ibed .

B iconst i tue n t f ib res consis t ing f ib r i l s o f a po lym er a l igned para l le l to the f ib re

leng th in te r sperse d in a con t inuou s m atr ix o f ano ther po ly m er and the i r s truc tu re ,

resem bles the b i la te ra l s t ruc tu re o f wool . C lear ly f ib r i l la r -matr ix ra t io and the na-

tu re an d r e l a t iv e d im en s io n o f th e co m p o n en t s can b e a l te r ed to v a r y th e p h y s ico -



4 4 Kin d s o f F ib re s

chem ica l p roper ties . Som e of the impor tan t b iconst i tuen t fib res a re Mon vel le (Ny-

lon/Spa ndex ) , Source (Polyester /Nylon ) , Ch inon (Acrylonitr i le /Ca sein) , M iraf i 140(Ny lon / Olef in ) , Po lych la l (Po lyv iny l ch lor id e /Po lyv in y l a lcohol) e tc . N ew and

im p r o v ed ty p es o f b ic o m p o n en t an d b ico n s ti tu en t fib re s co n t in u e to f in d in c r ea s-

ing ap plica t ion in kint t ing, ho siery a nd ca rpeting [ 105,106].

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33 R . Frey tag , Tex t i lve red lung , 11 (1976) 82 .34 A. C . W alk ar and M. H. Que l l , J. Tex t i le Ins t . , 24 (1933) T 131.

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252 .

36 In te rna t ion a l W oo l Secre ta r ia t c i ted by [37 ].

37 E . V . T r u te r , W ool wa x ( L ondo n C le a ve r - H um e Pr e ss , 19 56 ).

38 M. L . Sch loss m an and J . P . M cC ar thy , J. Am er . Oi l Ch em. Soc . , 55 (1978)

447 .

39 H. R . Ch ipa lka t t i , A. D. Sule , K. K. June ja and M. C . Agga rwa l , J . Tex t i le

Inst . , 56 (1965) T 649.

40 U. Ka lkbrenner , A. Kroner , H. Hocker and D. E . R ive t t , Schr i f t , DWI, 105

(1990) 67.

41 A .P . N egar i , H. J . Co m nel , D. E . R ive t t , J. Soc . Dy ers Colou r is t s , 109 (1993)

296A.

42 A. P. Ne gar i , H. J. Co m el l and D. E . R ive t t , Text i le Res . J. , 63(2) (1993) 109 .

43 J . D. Le ed er and J . A. Rip po n, J . Soc. Dy ers Colo urists , 101 (1985) 11.




44 M . R a m a na tha n , T . S iko r sk i a nd H . J . Woods , I n t . Wool Te x t . R e s . C onf . ,

Aug. 1955, F 92.45 M. Hor io an d T. Kon do, Tex t i le Res . J ., 23 (1953) 373.

46 E. H. Me rcer , Tex t i le Res . J ., 23 (1953) 331.

47 Bo ne ' s an d T. S ikorski , J . Tex t i le Ins t . 58 (1967) 521.

48 J . W .S . He a r l e and R . H . Pe te r s, F ib r e S c ie nc e , B u t t e r wo r th & C o . , L ondon ,

1963.

49 E. Be nd it , Tex ti le Res. J ., 38 (1968) 15.

50 C. A. And erso n, J . Te xti le Inst . , 73 (1982) 289.

51 S .R . Ch r is toe , D. K. Pha m and B . O. Ba teup , Text i le Asia (Apr 1994) 45 .

52 A. M. Shisko e t a l ., Ve ts i Akad. Na vu k BSS R, Ser . Sc i. , 23 (1981) 197.

53 L .K . M in ic he v , Te c hno l . Te x t i l e I ndus tr . US S R , 5 ( 19 69 ) 141.

54 L . K. M inich ev, T ekhn ol Teks t i l Prom. , 72 (5) (1969) 139 .

55 L .V . Y uda e v a e t a l. , Te khno l . Te ks t i l P r om . , 157 ( 1 ) ( 1 9 8 4 ) 46 .

56 T. Todo rov, God. S of i l Univ . , B io l . Fak . , 59 (2) (1964/65) 59 .

57 R . Koz lowski and J . Tabisz , Proc . Ins t . Prezm. Wlok Lykawyeh, 15 (1968)

113.58 H.S .S .Sh arm a , B io techno l . le t t ., 8 (1986) 219 .

59 A. M. Shishko , Kh im. Drev . , 1 (1984) 95 .

60 J . A Turn er , J . Te xti le Inst . , 39 (1948) 150.

6 1 C . B lum , Eur ope a n Te x t i l e R e se a r c h : C om pe t i t i ve ne ss th r ough innova t ion ,

Elsevie r , London, 1985.

62 N. B. Paul and S. K. Bh attac har ya, J . Te xti le Inst . , 70 (1979) 512.

6 3 G . B . B r a v ' ova , K. A . Ka lun ya n t s a nd R . N . Gr e be shova , T r - Vse s , Na uc hn o-

I ss led , Ins t . B ios in t . Be ko vy kh V eshch es tv , 2 (1974) 177 .

64 P . A. Ro e lofose n , T ext i le Res . J. , 21 (1951) 412.

65 J . O. Wa rw icke r , J . Polym . Sc i , Pa r t A-z , 4 (1966) 571.

66 P . K. Roy, S . C . Bag an d A. C . Chakrab or ty , J . Appl . Polym . Sc i . , 19 (1975)

999.

6 7 D . H . B ow e n , S t r uc tu r e a nd m or ph o log y o f ve ge ta b le f ib re s , I J IR A, Go lde n

Jubi lee Seminar , 6 -7 th Nov. 1987 .

6 8 G e r m a n P a t e n t 9 8 64 2 , M a n u f a c tu r e o f C u p r a m m o n i u m R a y o n F i l a m e n t s,He r m a nn Pa u ly .





48 Kinds o f F ib res

97

98

99

F. C . A. A., van Berkel and H. Grot jahn , Appl . Polym er-Sy m p. No. 21 (1973)

67.B. Von Falkai and E. C . W em er , M el l iand T ext i lber ., 53 (1972) 1197.

H. L. Ne edles , Tex t i le Fibres , Dyes, Finishes a nd Processes - A concise Guide ,

No yes Pub . , N ew Je rsey , US A , p 117 .

100 F . March in i , Ch em iefase m / Tex t i l i ndus t r i e , 40 /92 (1990) E 137.

101 G. Av iv, J. Soc. Dy ers Co louris ts , 105 (1989) 406.

102 F . March in i and V. Massa , Chem iefase rn / Tex t i l i ndu s t r i e , 38 /90 (1988) T5 .

103 H. Ebn eth , Tex t i lveredlun g, 21 (1986) 105.

104 K. V. Da tye, Rev. Prog. Col . , 21 (1991).

105 H. Res t , Ho s iery Times , No. 40 (1967) 75.

106 An on, Hos iery Trade J ., (June 1966) 92.



Chapter 2

P R E P A R A T I O N B E F O R E C H E M I C A L P R O C E S S E S

2 . 1 I n t r o d u c t i o nAf te r the g r e y f a b r i c s ha ve be e n r e c e ive d in the g r e y r oom by the f in i sh ing

e n te r p r i s e s , t he ba le s a r e ope ne d a nd in spe c te d , a p r oc e ss wh ic h i s i nc r e a s ing ly

m e c ha n ic a l , bu t m uc h o f i t r e m a ins sub je c t ive . The m o s t im por t a n t po in t is t o

obta in fab r ic s" f ree from exte r ior im pu r i t ie s" in order to achieve sm ooth and t rouble

f ree resul t s in the subsequent f in ish ing sys tems.

2 .2 I n s p e c t i o n

I t i s c he c ke d wh e the r the g r e y f a b r ic s a r e in c onf o r m i ty w i th s t a nda r ds , a nd a ll

we a v ing f a u l t s a r e m a r ke d ou t . Fa b r i c in spe c t ion invo lve s th r e e poss ib l e s t e ps :

pe r c h ing , bu r l ing a nd m e nd ing . Pe r c h ing i s a v i sua l i n spe c t ion a nd the na m e de -

r ive s f r om the f r a m e , c a l l e d a pe r c h , o f fr o s t ed g l a s s w i th l i gh t s be h ind a nd a bove

i t. Th e fabr ic passes thro ugh the pe rch and i s inspec ted (Fig . 2-1) . F laws, s ta ins or

F igu r e 2 - 1 . Pe r c he s use d f o r in spe c t ion o f fa b r ic ( C o ur t e sy o f S p r ings M i l l s ).



50 P r e p a r a ti o n B e f o r e C h e m i c a l P r o c e ss e s

spo t s , ya m kno t s a nd o the r im pe r f e c t ions a r e m a r ke d . B ur l ing i s t he r e m ova l o f

ya m kno t s o r o the r im pe r f e c t ions f r om the f a b ri c . The f a u l t s a r e the n m e n de d a nd

a ny kn o t s in the m a te r i a l a r e the n push e d to the ba c k . M e nd ing , i s obv ious ly , t he

a c tua l r e pa i r o f im pe r f e c t ions . Kno t t ing shou ld be done c a r e f u l ly a nd tho r ough ly

so tha t t he r e pa i r o r ho le s i s no t v i s ib l e .

The r e c e n t i nnov a t ion i s the c lo th in spe c t ion b y the use o f la se r be a m s . S ta ins ,

ho le s , t h i c k a nd th in p l a c e s , a nd wa r p o r we f t t h re a d b r e a ks a r e de te ct e d . The a ppa -

r a tus wo r ks by the on - l ine sys t e m a nd e l im ina te s hum a n e r r o r c a use d by t i r e dne ss ,

thus e nsu r ing c ons ta n t ly un i f o r m f a b r ic qua l i ty . S u c h a ppa r a tus ope r a t e s on th r e e

d i f f e r e n t p r inc ip le s , na m e ly , t he c oa x ia l, re m is s ion a nd t r a nsm is s ion m e tho ds . I nthe c oa x ia l m e tho d the sc a n ne r l i gh t be a m i s r e f l e c t e c d ba c k to i ts sou r c e ( r e tr o -

r e f l e c t ion ) on to a r e c e ive r s i tua t e d in the op t i c a l hand . I n the r e m is s io n m e thod the

e m i t t e d l i gh t be a m i s r e c e ive d a t a f r e e ly a d jus t a b le a n g le by a li gh t gu ide sys t e m

a nd c onduc te d to the s igna l c onve r t e r . The t r a nsm is s ion m e thod use s a r e c e ive r

sys t e m loc a te d be low the pa th o f the f a b ri c wh ic h m e a su r e s the l i gh t pa s s ing th r ough

the we b . A sys ( e m f o r su r fa c e m o n i t e r ing o f w ove n a nd kn i t t e d f a b r ic s i s show n in

F ig . 2 - 2 . The l igh t sou r c e ( 1 ) is a he l ium ne o n l a se r o r a xe no n h igh p r e s su r e l a m p ,

Figure 2-2 . C lo th inspec t ion by la se r beam s us ing the " S ic k-

S c a n - S y s te m K o - R e - T r a " ( C o u rt es y o f E . S i ck , G m b H ) .

the l i gh t be a m f r om whic h pa s se s th r ough a n op t i c a l sys t e m ( 2 ) on to a l e ns ( 3 ) .

F r om he r e the l i gh t be a m i s p r o je c t e d on to a fa s t - ro t a t ing m ul t ip l a na r m i r r o r whe e l

( 4 ). The l igh t be a m be c o m e s a t ra ve l l ing be a m by the r o ta t ion o f the m i r r o r wh e e l



P r e p a r a ti o n B e f o r e C h e m i c a l P ro c e s s e s 51

a nd i s de f l e c t e d th r ou gh the p l a na r m i r r o r ( 5 ) on to a pa r a bo l i c r e f l e c to r w i th a xe s

pa r a l l e l a nd f oc usse d by the c y l inde r l e ns ( 7 ) on to the we b pa th ( 8 ) . The be a mguid ing sys t e m e nsu r e s tha t the l i gh t be a m a lwa ys s t rike s the c lo th pa th a t the sa m e

a n g l e . T h e l i g h t r e c e i v e r i n t h e r e m i s s i o n a n d t r a n s m i s s i o n m e t h o d s i s a

ph o toc on duc to r [ (9 ) fo r r e m is s ion , ( 10 ) f o r t r a nsm is s ion ] w h ic h c on s i s t s o f a n op -

t i ca l ly h i g h g r a d e l ig h t c o n d u c t i n g m a t e ri a l o f h i g h h o m o g e n i t y a n d l o w a b s o r p -

t ion . The p ho toc o ndu c to r i s a t t a c he d a t the f r on t su r f a c e to a p l a na r m i r r o r a nd a t

the o the r e nd to a pho to r e c e iv e r ( 11 ) wh ic h c o nve r t s t he a m o un t o f l i gh t in to s ig -

na l s . The f a u l t s igna l s pa s s f r om the m on i t e r ing a pp a r a tus th r ough a n a m p l i f ie r to a

c e n t r a l e l e c t ron ic un i t t o wh ic h m a y be c o nne c te d to a da ta inpu t , a d i sp la y un i t, a

r e c o r de r , a c oun te r w i th a c ous t i c a l a r m , a m a r k ing de v ic e , a da t a s to r e a nd /o r a

printer.

2 .3 Sewing

A f t e r th e g o o d s h a v e b e e n i n s p e c te d , c h e c k e d a n d c l a s s e d i n th e g r e y r o o m ,

a c c or d ing to qua l i ty a nd s t a m pe d , t he y a r e s e wn toge the r , e nd to e nd , by se wing

m a c h in e s e sp e c ia l ly c ons t r uc te d f o r th i s pu r pose . Th e r e a r e va r ious type s o f s e w-

ing m a c h ine s [F ig . 2 - 3 ( a ) & ( b )] . The f a b r ic s a r e u sua l ly s e w n on c i r c u la r m a c h ine .

Figure 2-3(a ) . Por table sewing machine

(Cour tesy of Gebr. Doh le Gm bH & Co. ).

jo in in g p iece lengths of fabr ic (Co ur tesy

of Meta ]p las t , I ta ly) .



52 Pr e pa r a t ion B e f o r e C he m ic a l P r oc e sse s

The po r t a b le R o ta r y S e wing M a c h ine i s ve r y ha ndy . The m a in d i f f i c u l ti e s a r e be n t

se lvedges . S t i tch ing should be done in such a manner tha t the c reases in fabr ic a tthe t im e o f s t it c h ing shou ld be a vo ide d . The use o f p r ope r s t i tc h ing th r e a d i s ne c e s -

sa r y to a vo id s t i t c h m a r ks du r ing c o lou r pa dd ing . Fo r he a vy f a b r i c s in t e nde d f o r

m e r c e r i z ing a nd c on t inuous ope r a t ions , t he se a m shou ld be w ide r ( 15 m m ) a nd

s t r onge r. S om e t im e s , g lue ing o r bond ing o f f ab r i cs to b ind the e nd p ie c e s by f us ing

po lym e r f i lm s und e r the a c t ion o f h igh t e m p e r a tu r e i s u se d in s t e a d o f s e wing to

r e duc e the a m oun t o f r a gs . Goods o f s im i l a r we igh t , w id th a nd c on s t r uc tion a nd the

goods wh ic h wi l l r e c e ive a s im i l a r t r e a tm e n t i s ba t c he d toge the r a nd e a c h lo t i s

g ive n a num be r .

2 .4 M e c h a n i c a l C l e a n i n g o f F a b r i c s

The p r e - c l e a n ing o f g r e y f a b r ic s m a y be c a r ri e d ou t i n a s e pe ra t e un i t j u s t b e f o r e

c r opp ing a nd she a r ing ope r a t ions . The e f f i c i e nc y o f p r e - c l e a n ing i s t he founda t ion

of good c r o pp ing a nd she a r ing . The p r e - c l e a n ing o pe r a t ion is a c h ie ve d w i th :

(i ) Th or ou gh g r ind ing o f the c lo th su r f a ce by e m e r y c ove r e d r o l le r s .

( ii ) S c r a p ing w i th su it a b le de s igne d a nd loc a te d sc r a p ing b la de s .

( ii i) Ef f ic ie nt brus hing on both s ides o f the c lo th .W i th the p r og r e s s o f g r ind ing a nd sc r a p ing a c t ion , t he c lo th su r f a c e ge t s c ove r e d

with th read ends , dus t , f luff , d i rt e tc . , thus the pre -c leaning uni t should h ave a good

dus t e xha u s t ing sys t e m .

2 .4 .1 Brush ing

The p u r pose o f b r ush ing i s to r e m ov e the sho r t a nd loose f ib re s f r om the su r f ac e

of the c lo th . I t a l so remov es h usk pa r t ic les c l ingin g to the c lo th . Brush ing i s m a in ly

done to f a b r ic s o f s t a p le f ib re c on te n t , a s f i la m e n t ya m s usua l ly do no t ha ve loose

f ibre ends . Cy l inders cov ered w i th f ine br is t le s ro ta te ov er the fabr ic , p ick up loo se

f ib r e s , a nd pu l l t he m a wa y b y e i the r g r a v i ty o r va c uum . T he r a i se d f ib re e nds a r e

c u t o f f du r ing she a r ing ope r a t ion . B r ush ing be f o r e c r opp ing m in im ise p i l l ing .

2 .4 .2 C r o p p i n g a n d s h e a r i n g

S he a r ing i s an ope r a t ion c ons i s t s o f c u t t ing the loose s t r a nds o f fib r es f r om

e i the r su r f a c e o f a f ab r i c w i th a sha rp e dge d r a z o r o r s c i s so r s . B y m a n ipu la t ing the

shear ing i t i s a l so poss ib le to cu t des igns in to p i le fabr ics . Good c ropping i s pe r -

ha ps , t he s im p le s t wa y o f r e duc ing the t e nde nc y o f b l e nde d f a b ri c s to ' p i l l ' . I n thecase of co t ton fabr ics , in pa r t icu la r , ca re should be taken to see tha t the shear ing



P rep a ra t i o n Be fo re Ch em i ca l P ro ces s e s 53

b l ad es d o n o t s c r a t ch t h e s u r face o f t h e f ab r ic , w h i ch o t h e rw i s e can cau s e d y e i n g

d e fec t s d u r i n g s u b s eq u en t d y e i n g .F ig . 2 -4 shows a four -cu t t e r shear ing machine and F igs . 2 .5 and 2 .6 show the

Figure 2-5. Typical 2-cutter cropping m ac hin e. Fig ure -6. Typical 4-cuttercroppingmachine.

s i mp l i f i ed l in e d i ag ram s o f 2 an d 4 -cu t t e r mach i n es w h i ch i ll u s tr a t e t he s h ea r i n g

an d c ro p p i n g . T h e m ach i n e co n s i s ts o f a st ro n g f r ami n g ca r ry i n g fo u r r ev o l v i n g

cu t te rs f i t t ed wi th l e f t and r igh t hand sp i ra l b lades . A 4-cu t t e r machine has fourcu t t ing po in t s , two fo r the face and two fo r the reverse s ide . The t e rm 'cu t t ing



5 4 P r e p a r a ti o n B e f o r e C h e m i c a l P r o c e s s e s

po in t ' de no te s the c on ta c t l ine be tw e e n the sp i r al she a r ing c y l inde r a nd the l e dge r

b la de , ove r wh ic h the f a b r i c ha s to pa s s du r ing c r opp ing a nd she a r ing ope r a t ion .Ea c h c u t t e r i s p r ov ide d w i th a d jus t a b le l e dge r b l a de . B e f o r e l e a v ing the m a c h ine ,

the c lo th i s b r ushe d by a sp i r a l r e vo lv ing b r ush . The m a c h ine s a r e o f t o t a l ly e n -

c l o s e d c o n s t r u c t i o n w i t h e x h a u s t c h a n n e l s . A l t h o u g h t h e r e h a v e b e e n n o m a j o r

c h a n g e s i n th e l a te s t cr o p p i n g a n d s h e a r in g m a c h i n e s , a m o d e m f u ll y a u t o m a t i c

she a r ing r a n ge ( F ig . 2 - 7 ) ha s the f o l low ing f e a tu r e s :

( i) Fabr ic feeding device (e lec t ronica l ly cont ro l led) ensur ing the ent ry of c rease

free fabr ic .

( ii ) A sof t bed u nde r the cut te r s so tha t the b lades w hich cu t the f ibres c lose to

the su r f a c e do no t da m a ge the f ib r e s in the ya m .

( ii i) S e a m jo in t s e nso r s ( e l e c t r on ic ) wh ic h l i ft the she a r ing r o l l s a wa y f r om the

f a b r i c su r f a c e wh e n a s e a m pa sse s .

( iv ) M a gn e t i c m e ta l de t e c to r s s e nse the i r on pa r t i c le s e m be d de d w i th the c lo th

a nd a c t iva t e the l im i t ing swi t c h , so tha t t he m a c h ine s tops , t he c onc e r n e d

pa r t i c l e s a r e r e m ove d a nd the m a c h ine r e s t a rt e d .

( v) Hy dr a u l i c sp e e d ge a r sys t e m ha s be e n r e p la c e d by su i t a b le DC d r ive s .M o d e m s h e a r i n g m a c h i n e c a n o p e r a t e u p t o a s p e e d o f 1 0 0 m / m i n . T h e

uni ts have be en m ade m ore m odu la r , in order to fac i l ita te quick ins ta l la t ion .

F igu r e 2 - 7 . Fu l ly a u tom a t i c she a r ing r a nge [C our t e sy o f S wis s

A s s o c i a t i o n o f M a c h i n e r y M a n u f a c t u r e r s ( V S M ) ] .S he a r ing m a c h ine s f i tt e d w i th se r r a t e d b l a de s ha ve be e n f ound sa t i s f a c to r y f o r



P r e p a r a t io n B e f o r e C h e m i c a l P r o c e s se s 55

the c u t t ing o f po ly e s t e r m a te r i a l s . Po lye s t e r s t a p le f ib r e f a b r ic s a r e c r opp e d a n d

s inge d m a in ly to c on t r o l t he p i l l i ng t e nde nc y . Fo r po lye s t e r /woo l b l e nde d f ib r efabr ics a g oo d c ro pp ing i s e ssent ia l i f the fabr ic i s not to be m i l led . I f it is des i red to

f in i sh s im u la t ing w oo l , l oose po lye s t e r shou ld f ir s t be r e m o ve d b y b r ush ing , c r op -

p ing a nd s inge ing a nd the n the f a b ri c is soa p - m i l l e d to p r oduc e a wo o l c ove r , wh ic h

c a n be c r oppe d to g ive the r e qu i r e d a ppe a r a n c e a nd ha nd le .

2.5 S ingeing

The a im o f s inge ing i s t o bum - of f t he p r o t rud ing f ib re s a nd ha i r s f r om the f a b r ic

s u r fa c e . T h e s p i n n i n g p r o c e s s p r o d u c e s h a i ri n e s s o f th e y a m a n d l o w e r t h e y a r n

c oun t s ( Ne 26 /1 - 36 /1 ) g r e a te r is t he de g r e e o f ha i r ine s s . T he r e f o r e the r e a sons f o r

s i n g e i n g s h o u l d b e c o n s i d e r e d m o r e c l o se l y .

(i ) S inge ing im p r ove s the e nd use a nd we a r ing p r ope r t i e s o f t e x i le s .

(i i) The bu r n ing - o f f o f p r o t r ud ing f ib r e s r e su l t s in a c l e a n su r f a ce wh ic h a l lows

the su r uc tu r e o f the f a b r ic m or e c l ea r .

( ii i) S inge in g r e duc e s the f ogg in e ss c a use d by d i f f e ring r e f l e c t ion o f l i gh t by

the p r o je c t ing f ib r e a nd the dy e d f a b r i c s a ppe a r b r igh te r .

( iv ) S inge in g i s a n e f fe c t ive m e a n s o f r e duc in g p i l l ing in b l e nd e d f a b r i c s c on -ta in ing synthe t ic f ibres .

(v ) Un s ing e d f a b r i c s so i l m or e e a s i ly tha n s inge d fa b r ic s .

(v i) A c lose ly s ing ed fabr ic i s e ssen t ia l for pr in t in g f ine in t r ica te pa t te rns .

( v ii ) S inge ing p r oc e ss f a c i li t a te s a n d spe e ds up d e s i z ing , i f t he f a b r i c i s im pr e g -

na te d w i th de s i z ing l iquor im m e dia t e ly a f t e r s inge ing .

On the o the r ha n d the r e a r e s inge ing f a u l ts wh ic h a r e no t v i s ib l e a nd onc e oc -

c u r r e d c a n no lon ge r be r e pa i r e d . The y a r e :

( i) Un eve n s inge ing e f fec t can cause s t reaks w hen the fabr ic i s dyed, or bub bles

w he n the f a b r i c i s fin i she d .

(i i) I n the c o t ton sy s t e m s inge ing i s done on the g r e y c lo th , bu t f o r b l e nd e d

f a b r i c s c on ta in ing syn the t i c f ib r e s g r e y s t a te s inge in g i s no t a d v i sa b le be -

c a use sm a l l g lobu le s o f m e l t e d syn the t i c f ib r e s a bso r b dye p r e f e r e n t i a l ly ,

g iv ing c lo th a spe c k le d a ppe a r a nc e .

( ii i) Th ere i s a pos s ib i l i ty o f the rm al d am age to tempe ra ture sens i t ive f ibres , for

ins tance polyes te r .( iv ) S top - o f f s c a n c a use he a t ba r s on f a b ri c s . C r e a s ing p r oduc e s s t r e a ks wh ic h

i s m a g n i f i e d w h e n d y e d .



56 P r e p a r a ti o n B e f o r e C h e m i c a l P r o c e ss e s

( v ) P r o t r ud ing f ib r e s a r e f i rm ly bou nd by s inge ing on the su r fa c e by the s i z ing

a ge n t by ha r de n ing o f the s i z e a nd c a n l e a d to d i f f ic u l t i e s in de s i z ing .( v i) W he n s inge ing i s done a f t e r dye ing , he a t c a n c a use c o lou r lo s s f r om po ly -

e s t e r p o r t i o n o f th e b l e n d b e c a u s e o f s u b l i m a t io n o f d y e .

( v ii ) Th e r e m a y be r e d uc t ion o f t e a r s t r e ng th due to ov e r s inge ing o f the f a b r ic .

Ge ne r a l ly , s inge ing i s done on bo th s ide s o f t he f a b r i c . No c he m ic a l c ha nge

oc c ur s in the f a b r ic du r ing s inge ing a nd the r e a c t ion i s ba s i c a l ly one o f ox ida t ion .

S i n g e i n g a n d d e s i z i n g c a n b e f r e q u e n t l y c o m b i n e d b y p a s s i n g t h e s i n g e d c l o t h

t h r o u g h t h e w a t e r b a t h w h i c h i n c l u d e e n z y m e s . T h e e n z y m e s d i g e s t t h e v a r i o u s

s i z ing a ge n t s , m a k ing i t e a sy to r e m ove the m dur ing the sc our ing ope r a t ion . The

c om bine d p r oc e ss a l so p r e ve n t s poss ib l e l a t e n t da m a ge to fa b r ic f r om the s inge ing

f l a m e o r he a te d p l a t e s .

2 . 5. 1 S i n g e i n g d i f f e r e n t k i n d s o f f i b r e s f a b r i c s

I n s inge ing the sho r t f ib r e s a r e bu r n t o f f f r om the su r f ac e o f the f a b r ic by d i r e c t

o r ind i r e c t he a t ing sys t e m s wi thou t da m a ge to the c lo th by sc o r c h ing o r bu r n ing .

The the r m a l be ha v iou r o f d i f f e r e n t k inds o f f ib r e s a r e d i f f e r e n t a nd s inge ing a t

h igh e r t e m p e r a tu r e i s na tu r a l ly a s so c ia t e d wi th g r e a te r ha z a r ds on e xc e ss ive c on-t a c t pe r iod a nd m a y c a u se the r m a l de g r a d a t ion o f the f ib r e.

I n c a se o f ve ge ta b le f ib r e s , g r e y s inge ing i s ne c e s sa r y a s it l e a ds to s l igh t ye l-

l o w i n g w h i c h n e e d s s u b s e q u e n t b l e a c h i n g t o g e t h i g h d e g r e e o f w h i t e n e s s. G r e y

s inge ing i s a l so e c onom ic a l a s s inge ing a t a ny o the r s t a ge s o f p r oc e ss ing r e qu i r e s

a dd i t iona l wa sh ing a nd d r y ing . Ve ge ta b le a nd r e ge ne r a t e d f ib r e s f a b r i c s c a n be

s inge d ve r y s t r ong ly w i th m a x im um bur ne r in t e ns i ty to ob ta in good r e su l ts . R e ge n-

e r a t e d f ib r e s no r m a l ly b um to a l it tl e l e s s e a s i ly tha n na tu r a l f ib re s .

W o o l h a s p o o r c o m b u s t i o n p r o p e r t ie s a n d a r e v e r y s e n s i ti v e to t e m p e r a t u r e s

and hen ce w ool len m ate r ia ls a re not subjec ted to in tense f lame l ike cotton . In wool len

f a b r ic f l a m e i s no t ge ne r a l ly a l low e d to pe ne t r a t e the m a te r ia l a nd th i s c a n be ob -

t a ine d by b low ing a i r t h r oug h the f a b r ic f r om the op pos i t e s ide o f the f l a m e so tha t

the f l a m e wi l l be r e s t r i c te d on ly on the su r f a c e o f the f a b r ic . A l t e r na t ive ly , t he

f a b r i c c a n be gu ide d to wa te r c oo le d gu ide r o l l e r s a l lowing the f l a m e to he a t t he

c lo th . W he n the f l a m e s t r ike s the f a b ri c i t i s r e f l e c t e d by a i r / s te a m c ush ion c r e a t e d

wi th in the m a te r i a l .Am on gs t t he sy n the t i c f ib re s po lye s t e r ha s the g r e a te s t s ign i f i c a nc e . I t m e l t s a t















P r e p a r a t io n B e f o r e C h e m i c a l P r o c e s s e s 63

t im e . T h i s d e p en d s o n t h e s p eed o f t h e f l am e an d h ea t cap ac i t y o f t h e f l am e . I t i s

u s u a l l y m e as u r ed i n m i l lim e te r h e ad w a te r o f t h e co m b u s t ib l e m ix tu r e o f t h e b u r n e r .T h e a c tu a l f l am e in t en s i t y f o r s in g e in g l i e s b e tw een 5 an d 2 0 m b ar s w h ich can b e

s e t st ep l e s s ly i n th e d es c r ib ed m an n e r .

T h e b u r n e r s h o u ld b e cap ab l e o f i n d iv id u a l s w iv e l l i n g to an d f r o m th e c lo th .

T h e s w i v e l l i n g m e c h a n i s m i s c o n n e c t e d t o t h e g a s s u p p l y s y s t e m , w h e r e b y t h e

b u r n e r s a r e au to m a t i ca l l y i g n i t ed o r ex t i n g u i s h ed . Du s t an d g as eo u s co m b u s t io n

p r o d u c t s a r e ex h au s t ed t h r o u g h a v en t i l a t i o n h o o d a r r an g ed ab o v e t h e s i n g e in g

m ach in e . S in g e in g r o o m s h o u ld b e w e l l v en t il a t ed , s p ac io u s an d f i r e -p r o o f .

M o d e m s i n g e i n g m a c h i n e s i n c lu d e p n e u m a t i c a d j u s t a b le f ir in g p o s it io n , u l t ra -

v io l e t f l am e s can n e r , b u i l t - i n f l am e ex t r ac t i o n s y s t em , f l am e s h ea r in g e f f ec t , im -

p r o v ed g u id in g s y s t em , h ig h f r eq u en cy b u r n e r s an d v a r i ab l e s p eed an d ad ju s t ab l e

b u r n e r s . T h e u s e o f d o u b le j e t b u r n e r i n i t i a t e s s i n g e in g b y m ean s o f an i n t en s e

c o n c e n t r a t e d a n d h o m o g e n e o u s f l a m e a n d s n a g m e t i c c o n t r o l s y s t e m f o r c o n t r o l -

l ing a ll f l ame param eter s . S ingeing mach ine i s equ ipped w i th m eter counter s , speedo-

m e t e r a n d a t h e r m o c o u p l e w i t h a s ta t io n a r y m u l t i v o l t m e t e r f o r m e a s u r i n g t h e t e m -

p e r a tu r e o f s i n g ed s u r face . A l l m o d em s in g e in g m ach in e i s e l ec t ro n i s ed , w i th ad d edd ev ice o f w ar n in g n o i s e o r fi re a l a r m in t h e ca s e o f a fi re . As an ad d ed p r ecau t io n ,

w e t s p r in k l e r s an d u n b u r n t g as d e t ec to r s h av e a l s o b eco m e n e ces s a r y d u e t o st ri n -

g en t s a f e ty r eg u l a t i o n s . Ap ar t f r o m th es e f ea tu r e s , s i n g e in g m ach in e r i e s s h o u ld

a l s o h av e s t eam q u en ch in g f o r t h o s e s o r t s o f fab r ic w h ich a r e n o t t o b e w e t t ed , e . g .

g r ey m er ce r i ze d f ab r ic s .

2 . 5 . 5 . S i n g e i n g c i r c u l a r k n i t f a b r i c s

As w i th w o v en f ab r ic s , h a i r i n es s o f t h e f ace o f k n i t t ed f ab r i c s i s s e ld o m d es i r -

ab l e . T h e r e a r e v a r io u s w a y s t o av o id th i s p r o b l em . T h e y a r n q u a l i t y , u n i f o r m f ace

ap p e a r an ce an d p r o p e r y a r n co u n t a re im p o r t an t f ac to rs w h er e t h e q u a l i ty o f k n i t -

t ed f ab ri c i s co n ce r n ed . T h e q u a l i t y can b e f u r th e r im p r o v ed b y ad d i t i o n a l p r o ces s

s tage such as , fo r ins tance , s ingeing .

The s ingeing m achine fo r c i r cu lar kn i t f abric d i ff e r s f rom the w el l -know n s ingeing

m ach in e f o r w o v e n f ab r i c s o n ly i n g u id in g an d t r an s p o r t o f t h e f ab r ic . T h e r ea l

p r o b l em co n s i s t s i n p r o p e r ly o p en in g o u t t h e t u b u l a r f ab ri c . T h e d i s t an ce b e tw ee n

b u r n e r an d f ab r i c m u s t b e ex ac t l y t h e s am e a t ev e r y p o in t . T h e b u r n e r m u s t b e s od es ig n ed t h a t t h e r e i s an u n i f o r m f l am e in t en s i t y o v e r t h e en t i r e t u b e c i r cu m f e r -



64 P r e p a r a ti o n B e f o r e C h e m i c a l P r o c e s se s

e n c e . T h e b u r n e r m a y b e r i n g - s h a p e d , a n d t h e t u b u la r f a b ri c to o m u s t b e o p e n e d

ou t in a c ir c u la r f o rm . A h igh c a pa c i ty doub le j e t bu r ne r s c a n a l so be use d . B a s e d

o n t h e a u t o m a t i c a l l y a d j u s ta b l e s y s t e m , D o m i e r ( G e r m a n y ) a n d o t h e r m a n u f a c t u r -

e r s l i ke R im m e r , B r a z z o l i , Os tho f f e t c . ha v e de ve lope d a c ir c u la r s inge ing c onc e p t

to s inge kn i t good s in tubu la r f o r m w i thou t e dge m a r ks . T he f a b r i c is gu ide d to the

c i r c u la r e xpa n de r v i a tu r n ta b le a nd de twis t e r ( F ig . 2 - 13). The f a b r i c r uns th r oug h

Figur e 2 - 13 . S inge ing m a c h ine f o r c i r c u la r kn i t

f a b r ic ( C our t e sy o f Do r n ie r Ga sse l l s c ha f t m bH ) .

t h e m a c h i n e i n a n u p w a r d m o v e m e n t , t h e r e b y a i d i n g t he e f f e ct o f th e e x h a u s t d e -

v ic e , wh ic h i s a lso f i t te d a bove the bu r ne r in c i r c u la r a r r a nge m e n t . The e xpa nde r

a pp l i e s t e ns ion , wh i l e e igh t swive l l ing bu r ne r s a r e a r r a nge d on a r ing in suc h a

m a nn e r tha t , e ve n wi th w id th a d jus tm e n t s , t he fu l l w id th o f the f la m e o f e a c h se g -

m e n t i s a pp l i e d to the f ab r ic . I n the ga s s inge ing p r oc e ss , t he f l a m e in t e ns i ty o f 7 0

to 10 0 m m wa te r c o lum n i s su i t a b le . I n the s inge ing a r e a the r e i s p r a c t i c a l ly no

long i tud ina l t e ns ion . Af te r l e a v ing the gu ide e xp a nde r the f a b r ic i s t he n t a ke n o ve r

by the d r iven spark ext ingu ish ing and p la i t ing uni t. Al l da ta such as d iamete r , burner

dis tance , burne r in tens i ty and speed a re cont ro l led f rom a com pute r te rmina l . S inge-

ing a nd c e l lu l a se e nz ym e t r e a tm e n t to de f uz z a nd im pr o ve the v i sua l a ppe a r a nc e i s

thus a be s t c ho ic e to g ive the c on sum e r a va lue - a dde d qu a l i ty o f kn i t f a b r ic s .



P r e p a r a t io n B e f o r e C h e m i c a l P ro c e s s e s 65

2 .6 P r o c e s s S e q u e n c e

T h e s e l ec t i o n o f co r r ec t p r o ces s s eq u en ce h as a d i r ec t b ea r in g o n t h e q u a l i ty o ff u r th e r p r o c es s in g o p e r a t i o n s s u ch a s d y e in g , p r in ti n g , f i n i s h in g e tc . So m e 60% o f

a ll th e p r o b l em s o ccu r in g i n s u b s eq u en t p r o ces s in g g en e r a l l y o r ig in a t e f r o m a w r o n g

an d in ad eq u a t e s e l ec ti o n o f p r o ces s s eq u en ce . P r ec i s e req u i r em en t s o f f ab r ic p r ep a -

r a t i o n d e p en d o n t h e k in d o f f ib r e an d i t s p r o p o r t i o n co n t a in ed i n t h e b l en d s , f ab r i c

co n s t r u c t i o n , s i ze ty p e a n d l o ad in g an d t h e en d u s e . Co t to n k n i t t ed f ab r i c s a r e s u b -

j e c t e d t o a m o d i f i e d r o u t in e i n w h i c h s i n g e in g a n d d e s i z i n g s t a g e s a r e s o m e t i m e s

o m i t t ed , w h e r eas f o r w o v en f ab r i c s d es i z in g can n o t b e o m i t t ed . Sy n th e t i c f i b r e s

a r e p r o d u ced u n d e r co n t r o l l ed co n d i t i o n s an d co n t a in o n ly ad d ed im p u r i t i e s , t h e i r

c l e a n i n g i s c o m p a r a t i v e l y e a s y . H o w e v e r , w h e n t h e y a re u s e d i n a d m i x t u re w i t h

n a tu r a l f i b re s , th e p r o b l em s ag g r av a t e . P r ep a r a t i o n o f f ab r ic a l s o d ep en d s o n t h e

e n d re q u i r e m e n t . F o r e x a m p l e , " f u l l w h i t e b l e a c h " i s d o n e i n t h e c a se o f g o o d s

w h ich a r e t o b e s u p p l i ed w h i t e , ' h a l f b l eac h ' f o r o v e r d y e in g o r w h en e v e r b ig b lo tch

an d f u l ly co v e r ed d es ig n s a r e to b e p r in t ed an d ' f u l l b l eac h ' w h en ev e r p as t e l s h ad es

a r e t o b e d y ed . Co t to n f ab r i c s t o b e d y ed i n d eep s h ad es w i l l m o s t l i k e ly r eq u i r e

m er ce r i za t i o n i n o r d e r to im p r o v e t h e i r d y eab i l it y .F a b r i c p r e p a r a t i o n i s a c o s tl y s e r ie s o f e n e r g y c o n s u m i n g p r o c e s s e s . E c o n o m i c

co n s id e r a t i o n , t h u s , h av e l ed t o co n s id e r ab l e m o d i f i ca t i o n o f t h e ex i s t i n g p r o ces s -

in g s eq u en ces . T h e t r ad i t io n a l s eq u en ce o f p r e - t r ea tm en t i s s h o r t en ed b y s in g l e

s t ag e b l each in g , w h e r e k i e r s a r e s t il l in u se . I t i s t h e r e f o r e n ec es s a r y t o b a l an ce t h e

c o s t o f p r e p a r a t i o n b y o p t i m i z i n g t h e p r o c e s s s e q u e n c e , c o n d i t io n s a n d d e v e l o p -

m e n t o f sh o r t e r r o u te s . F u r t h e r m o r e , s e v e ra l n e w t y p e s o f m a c h i n e r i e s a n d n e w e r

p r o c e s s e s h a v e b e e n e v o l v e d t o m e e t t h e r e q u i re m e n t o f e f fi c ie n t b u t e c o n o m i c a l

an d r ap id p r ep a r a t i o n o f c lo th . A l l th e s e f ac to r s n eces s i t a t e t h e a l t e r a t io n o f p r o ces s

s e q u e n c e t o g e t t h e o p t i m u m r e s u lt s a n d t h e te c h n o l o g i s ts c a n d e c i d e a s a n d w h e n

a n y o f t h e s t a g e s a r e to b e b y - p a s s e d w i t h o u t c o m p r o m i s i n g t h e q u a l i t y o f th e

goods . The seque nce g iven in th i s chap ter , therefore , se rves on ly a genera l gu idence .

2 . 6. 1 P r o c e s s s e q u e n c e f o r c o t t o n f a b r i c o n k i e r

M e t h o d A : F o r w h i t e / p r in t i n g : (P o p l in , Ca m b r i c , Ru b ia , M u l l s e t c .) Gr ey

m er ce r i ze --~ Sco u r i n k i e r --~ R in s e i n k i e r --~ W as h - ~ Ch em ick in g i n C i s t e r n

W as h --~ Op en b o i l i n k i e r u s in g H2 02 --~ R i n s e in k i e r - ~ W a s h ~ S c u t c h - ~ D r y .M e t h o d B 9F o r d y e in g : (P o p l in , Cam b r i c , Ru b ia , Mu l l s , S h ee t i n g s e t c . ) Gr ey



66 Preparation Before Chemical Processes

merce rize ~ Desize in Cistern --~ Was h -~ Scour in kier under pressure ~ Wash

Open boil in kier using U2 02 --} Rinse in kier ~ Was h ~ Scutch ~ Dry.2 .6 .2 P r o c e s s s e q u e n c e f o r c o t to n f a b r i c o n J -B o x

M e t h o d A 9For white/printing : Grey mercerize -~ Desize in J-Box Cistern -+

Was h --~ Caustic Saturator -~ Steam in J-Box ~ Wash ~ Chem ick Saturator -~

Store in J-Bo x --~ Perox ide Saturator -~ Steam in J-Box ~ Was h ~ Scutch -~

Dry.

M e t h o d B 9For dyeing : Grey mercerize ~ Wash ~ Caustic Saturator

Stea m in J-Bo x --~ Was h ~ Che mi ck Saturat or ~ Store in J-Box --+ Was h

Anti chlo r --~ Was h -~ Neutral ise ~ Scutch ~ Dry.

2 .6 .3 P r o c e s s s e q u e n c e f o r c o t t o n f a b r i c o n P a d - R o l l / T h e r m o r e a c t i o n

C h a m b e r (T.R.C.)

M e t h o d A : For whit e/pri nting : Singeing cum Desizing --~ Wash --~ Scour on

Pad-Ro ll (T.R.C.) --~ Was h --~ D ry --~ Merce rize -~ Bleaching on Pad-Roll (T.R.C.)

Ste ami ng ~ Was h ~ Dry.

M e t h o d B : For dyeing : Grey mercerize -~ Scour on Pad-Roll (T.R.C.) --~

Wa sh --~ Blea ch on Pad-Rol l (T.R.C.) ~ Was h ~ Dry.2 . 6 . 4 P r o c e s s s e q u e n c e f o r c o t to n f a b r i c o n J u m b o J i g g e r

M e t h o d A : For white goods : Grey me rceri ze -~ Scour on Jigger --~ Was h --~

Che mi cki ng --~ Was h --~ Perox ide Boil -~ Was h --~ Neutrali se --~ Unload.

M e t h o d B : For dyeing : Grey mercer ize --~ Scour at boil --~ Wash --~ Che micki ng

-~ Was h --~ Antic hlor ~ Was h --~ Neutra lise ~ Unload.

M e t h o d C 9For co lour ed wov en sorts : Grey mer ceriz e --~ Desize --+ Was h -~

Che mi ck in g --~ Wash --~ Pero xide Boil --~ Was h --~ Neutral ise --~ D r y - ~ Merceri ze

Dry.

2 . 6 . 5 P r o c e s s s e q u e n c e f o r k n i t t e d c o t t o n g o o d s

M e t h o d A : For white goods : Hypochlori te Bleach ~ Reduction or Peroxide

Bleach + Fluorescent Whitening Agent (FWA).

M e t h o d B : For white goods : Deminer alizati on acid med ium (metals) ~ Per-

oxide Bleach + FWA.

M e t h o d C : For white goods : Alkaline treatment + Demineralization (oils,

paraff in spots + metals) ~ Peroxi de Bleach + FWA.









70 Desiz ing

s t r a igh t c ha in po lysa c c ha r ide s o f g luc ose whe r e a s a m ylope c t in ( 7 0 - 8 0 %) be ing

wa te r insoluble i s d i f ficu l t to rem ove f rom cot ton due to it s h igh er molecu la r we ig hta nd b r a nc h e s c ha in (F ig . 3 - 2 ). Apa r t f r om s t a rc h , m o d i f i e d s t a r c he s suc h a s

A B

A A - "~,.. ~ ' ' ~- , <A

- a - I , c - i , . . . . . . . . . . . I - R A . - - - . - - . ~c ~, R...... ..... . .

A A

A(a) (b) (c)

F igu r e 3 - 2 . S c he m a t i c r e p r e se n ta t ions o f a m y lope c t in [2] .R = R e duc ing e nd .

A = No n- r e du c ing e nd o f s ing ly c onne c te d c ha in .

B = No n- r e du c ing e nd o f m u l t ip ly c onne c te d c ha in .

C = No n- r e duc ing e nd o f c ha in w h ic h c a r r i es a re duc ing e nd .

hydr oxye thy l s t a r c h , c a r boxym e thy l c e l lu lose ( C M C ) a nd na tu r a l gum s a r e a l so

used . Th e o the r s ize ingred ients pa r t icu la r ly use d in the case of regen era ted c e l lu-

lose f ibres a re pro te in based g lue , ge la t in e tc.

In synthe t ic f ibres the na ture o f s izes and s iz ing ingredien ts a re d i f fe rent . Syn-the t ic y a r ns a r e s t r onge r a nd he nc e inc r e a s ing s t r e ng th by s i z ing i s no t t he a im a nd

adh es ion of the s iz ing m ate r ia l to the ya rn i s a lso d i ff icu l t. S ta rch s iz ing of m an-

m a d e f ib r e s posse s s m a ny p r ob le m s w he n ya r ns a r e s la she d a nd f a b ri c s a re wove n .

Fur the r m or e , w i th the in t roduc t ion o f t e x tu r e d syn the t i c f ib r e ya m s , b l e nde d f ib r e

f a b r ic s , i n t r oduc t ion o f j e t l oom s , sys t e m o f dye ing a nd s iz ing toge the r, pe r m a na n t

a pp l i c a t ion o f s i z ing , so lve n t s i z ing e t c. , c ha nge the pa tt e r n o f s iz ing wi th c onve n-

t iona l s iz ing ingredients . The de ma nd for inc reas ing the warp speed has a lso led to

the de ve lop m e n t o f spe c ia l syn the ti c po lym e r s a nd pa r a f f in - ba se d lub r i c an t s . The

m a in syn the t i c s i z e s c om p r i se o f po lyv in y l a l c oho l (PVA) , po lya c ry l i c a c id , C M C ,

se r ie s o f p la s t i c i s e d a c id ic v iny l a c e ta te a nd a c id i c m e thy l a c r y la t e po lym e r s .

PV A i s the o lde s t a nd be s t know n g r oup o f syn the ti c s i z es . PVA dr ie s to f o rm a

tough to ha r d f i lm o f poor f l e x ib i l it y . The ba r s due to s toppa ge s in s i z ing o f pu r e

cot ton a re dreaded and cause d i f f icu l t ie s in dry sp l it t ing . The so lubi l i ty of PV A can

be im pa i r e d by he a t a pp l i e d d u r ing s i z ing , g r e y f ab r ic he a t - se t t ing o r s inge ing , a n

im p or t a n t po in t wh ic h in f lue nc e s de s i z ing . The va r ious g r ade s o f PVA c a n be

d i f f e r e n t i a te d de pe nd ing on the de g r e e o f hydr o lys i s ( o f a c e ta t e g r oups o f po lyv i -





7 2 D e s i z i ng

p o u n d t o e a s e th e i r r e m o v a l . T h i s is a c c o m p l i s h e d b y t r an s f e r r in g t h e s t a rc h i n t o

t h e i r s im p l e s u g a r s o r s i m p l e w a t e r s o l u b l e p o l y m e r s . T h e s y n t h e t ic s i z e s u s e d f o r

m a n - m a d e f ib r e s a re g e n e r a l l y w a t e r s o lu b l e a n d t h e y a r e r e m o v e d d u r i n g t h e s c o u r-

i n g o p e r a t io n .

3 .2 .1 Ro t s t eep ing

I n t h i s me t hod g re y c o t t on f a b r i c i s s t e e pe d i n w a t e r i n s u i t a b l e box a t a t e m-

p e r a t u r e o f a b o u t 3 0 -4 0 ~ D u r i n g t h e s t o ra g e m i c r o - o r g a n i s m s d e v e l o p e x c r e t i n g

e n z y m e s w h i c h a t t a c k t h e s ta r c h. T h e s w o l l e n a n d h y d r o l y s e d s t a r c h is t h u s p a r -

t i a ll y c o n v e r t e d i n t o s o l u b l e s ta t e w h i c h a r e t h e n r e m o v e d f r o m t h e f a b r i c b y n o r -

m a l w a s h i n g w i t h w a t er . T h e m a i n p r o b l e m s i n t h is m e t h o d a r e l o w e f f i c ie n c y d u e

t o l o n g e r t r e a t m e n t t i m e a n d d e g r a d a t i o n o f c e l l u l o s e d u e t o c r o s s - i n f e c t i o n s o f

m i l d e w i f t h e f e r m e n t a t i o n p r o c e s s i s n o t p r o p e r l y c o n t r o l le d .

3 .2 .2 Ac id des i z ing

I n th i s me t ho d c o t t on f a b r i c is t r e a t e d w i t h d i lu t e s u l phur i c a c i d w i t h a c on c e n -

t r a t i on o f 5 -10 g /1 a t a t e m pe ra t u r e o f a bou t 40 ~ fo r 3 -4 h . D i l u t e a c i d a t ta c ks t he

p o l y m e r c h a i n o f st a rc h a n d d u e t o c h a i n c l e a v a g e o f s ta r c h m o l e c u l e s h o r t w a t e r

s o l u b l e o r d i s p e r s ib l e c h a i n s e g m e n t s a r e f o r m e d . W i t h s u lp h u r i c a c i d h i g h e r t h a n10 g /1 a nd a b ove 50 ~ t he re is a l w a ys t he pos s i b i l i ty o f w e a k e n i n g t he c l o t h o r

c a u s i n g h o l e s [ 3 ,4 ] . T h e t r e a te d c l o t h m u s t n o t b e a l l o w e d t o d r y a t al l o t h e r w i s e

de g ra da t i on o f c o t t on w i ll oc c u r a t t he d r i e d ar e a . R i s e in t e mp e ra t u r e i nc r e a s e s t he

r a t e o f r e a c t i on , bu t a t t he s a m e t i me t he r e i s pos s i b i l i ty o f a t t a c k i ng t he c e l l u l os e

c ha i n . G e n e ra l l y , t he r a t e o f r e a c t i on dou b l e s fo r e a c h 10 ~ r i se in t e m pe ra t u r e .

T h e a c i d - s t e e p i n g m e t h o d i s p a r t i c u l a r l y s u i ta b l e f o r c o tt o n v a r i e t ie s c o n t a i n i n g

l a r g e m e t a l c o n t e n t s a s t h e m i n e r a l a c i d c o n v e r t s th e m e t a l s to t h e i r c o r r e s p o n d i n g

s u l p h a t e w h i c h a r e w a t e r s o l u b l e. T h e d e g r a d e d s t a r c h is r e m o v e d f r o m t h e f a b ri c

b y n o r m a l w a s h i n g t re a t m e n t .

3 .2 .3 Enzymat i c des i z ing

T h e w o r d e n z y m e is f r o m G r e e k w o r d s f o r ' i n y e a s t ' a n d w a s c o i n e d i n 1 8 76 b y

t h e G e r m a n b i o c h e m i s t W i l le y K u h n e [ 5] . E n z y m e s a re o rg a n i c b i o c a t a ly s t s h i g h l y

s pe c i f i c bo t h i n t he r e a c t i on c a t a l y s e d a nd t he i r c ho i c e o f r e a c t a n t s ( s ubs t r a t e ).

P h y s i c a l l y e n z y m e s a r e c o l lo i d a l n a tu r e a n d c h e m i c a l l y th e y a r e o f t h e n a t u r e o f

p r o te i n . E n z y m e s a re c o m p l e x a n d h a v e h i g h m o l e c u l a r w e i g h t s [6 ]. T o d a y e n -z y m e s a r e p r o d u c e d b y b i o t e c h n o l o g ic a l p r o c e s se s in g r e a t a m o u n t o f c o n s ta n t

qua l i t y , a nd a r e t he r e fo re a pp l i c a b l e to l a rge - s c a l e p roc e s s e s . A d va n c e s i n the f i e ld





74 D e s i z i n g

d i f f e r e n t e n z y m e d e s i z i n g p r o c e s s e s a r e c o m p a r e d w i t h r o t an d a c i d - s t e e p i n g i n

T a b l e 3 .1 . T h e l e n g t h o f t i m e f o r d ig e s t i o n w i ll v a r y w i t h t h e c o n c e n t r a t io n o fT A B L E 3 . 1 .

C o m p a r i s o n o f P r o c e s s C o n d i t i o n s f o r D e s i z i n g [ 8] .

P r o c e s s C o n c e n t r a ti o n T i m e T e m p e r a tu r e

(g / l) (hou r ) /pH (~

R o t - s t e e p i n g

H 2 SO 4 - s t e e p i n g

M a l t D i a s t a s e

P a n c r e a t i v e D i a s t a se

B a c t e r i a l D i a s t a se

- 10-16 h 30-4 0

5 - 1 0 3 - 4 h 4 0

(pH)3 - 2 0 4 .5 - 5 .5 5 0 - 60

1-3 6 .8-7 .5 50-6 0

0.5-1 6 .5 -7 .5 60-70

e n z y m e u s e d , t h e t e m p e r a t u r e o f t h e d e s iz i n g b a th , t h e ty p e s o f g o o d s b e i n g d e s i ze d

a n d b y t h e m e t h o d s d e p e n d i n g o n th e b a t c h o r c o n t in u o u s p r o c es s . C o m p a r e d t o

p a n c r e a t i v e e n z y m e , t h e m a l t e n z y m e h a s a l o w e r a c t io n e v e n w i t h th e a d d i t io n o f

m o r e a m o u n t o f e n z y m e . T h e u s e o f g r e at er a m o u n t o f e n z y m e t h an th e o p t i m u mw i l l n o t i t s e l f c o n v e r t t h e st a rc h . W h e n t h e g o o d s a r e p a d d e d w i t h d e s i z i n g m i x -

t u re , d i g e s t i o n o f th e s t a r ch i s a m a t t e r o f t i m e a n d t e m p e r a t u r e . A t l o w e r t e m p e r a -

t u re t h e d e s i z i n g e f f i c ie n c y i s a l so l o w e r . M a l t e n z y m e i s m o r e s t r o n g l y d e p e n d e n t

u p o n t e m p e r a t u r e t h a n o t h e r e n z y m e s . E v e n s o m e e n z y m e s a r e a v a il a b le w h i c h

c a n n o w b e w o r k e d a t 1 00 ~ s o t h a t h i g h te m p e r a t u r e d e s i z i n g is a r e a li ty . E n -

z y m e s a r e q u i t e s p e c i fi c i n t h e ir r e s p o n s e t o p H a n d r e q u i r e c l o s e c o n t r o l ( T a b l e

100 o~ 4009080 ~ 300

9 70 ~ 200

60 ~=

50 .~ 100

40 ~ - ; ' ~ _, - , ~5.0 6.0 7.0 8.0

pH

F i g u r e 3 - 3. E f f e c t o f p H o n e n z y m e

a c t iv i t y ( C o u r t e s y o f G r a h a m F i sh e r ,

G . B . F e r m e n t a t i o n I n d .) .

110 130 150 170

Temperature (~

F i g u r e 3 - 4 . E f f e c t o f t e m p e r a t u r e o n

e n z y m e a c t i v i t y [ 8] .



D e s i z i ng 7 5

3 . 1 ). The pH o f t he de s i z i ng ba t h is ma i n t a i ne d by a dd i ng a c i d o r a l ka li . The

e f f e c t s o f pH a nd t e mp e ra t u r e on e nz ym e a c t i v i t y a re s how n i n F i gs . 3 -3 a nd 3 -4r e s p e c t iv e l y . H o w e v e r s t o r in g t he e n z y m e a t a f ix e d te m p e r a t u r e s h o w s t h a t t h e

a c t i v i t y s t e a d i ly de c re a s e s w i t h ti me ( F i g . 3 -5 ) . I n ge ne ra l , c ha n ge s i n pH , t e m-

0" ~ ' i a l '~~~ - ......... ........................ i. ..~_~em yla se

.-~ 20 i ~ M a lt t n y l a ~ ~4 0

o 60O

-~ 80Pancreas amy lase -..

100 . . . . . . . . . . . _ ~ . . . ~ . . . . i ......... 9 . . . . .10 20 30 40 50 60

Minutes

F i gu re 3 -5 . D e c a y o f a c ti v i t y o f va r ious a m yl a s e s [ 9] a t 6 0~

pe ra t u r e a nd du ra t i on o f st o r i ng a l te r bo t h t he a c t i v it y a nd s t a b i l it y o f e nz y m e s ve ry

great ly.

S o m e t i m e s s o d i u m o r p o t a s s i u m c h l o r id e ( 0 . 1 8 - 1 . 0% ) i s a d d e d t o th e d e s i z i n g

ba t h fo r pa n c re a t i ve e nz ym e s t o ge t i ts f u ll a c t iv i t y . Fo r m a l t a - a m yl a s e c a l c i um

i on is e f f e c t i ve a nd s e qu e s t e r i ng a g e n t m us t be a vo i de d i n t he de s iz e ba th . Th e s e

s a l t s a r e pa r t i c u l a r l y u s e d fo r de s i z e mi x t u re by a f fo rd i ng he a t p ro t e c t i on t o e n -

z ym e , i nc r e a s e d s t a b i l i ty o f t he e nz y m e a nd e f f ic i e nc y . O n the o t he r ha nd , he a v y

me t a l i ons s uc h a s c oppe r , i r on et c. ma y c om bi ne w i t h e nz y me a nd i nh i b i t i ts a c ti v -

i ty [ 8] . S o m e t i m e s h yd roc a rbon s o l ve n t s s uc h a s xy l e ne ( 50 ml /1 ) a l ong w i t h s u i t -

a b l e e mu l s i f i e r ( 4 g / l) a r e a l s o a dde d to f a c il i ta t e r e mov a l o f w a xy c o m pon e n t s o fthe s ize .

F o l l o w i n g t h e d ig e s t io n p e r i o d , a h o t w a t e r w a s h , w i th o r w i t h o u t s u b s e q u e n t

a lka l ine scour , i s requ i red for com ple te rem ova l for the s i ze tha t has been so lubi l i s ed

b y t h e e n z y m e s .

3 . 2 . 4 D e s i z i n g w i t h o x i d i s i n g a g e n t s

Th ou gh t he us e o f ox i da n t s fo r de s i z i ng o f c o t t on f a b r i c is w i de l y a c c e p t e d bu t

t he i r l a rge s c a l e indus t r i a l a pp l i c a t i on i s ye t to be e xp l o i t e d . The m os t i m por t a n t

a s pe c t s o f ox i d i s i ng a g e n t s a r e tha t t he y c a n be a pp l i c a b l e t o w i de r a ng e o f f a b r i c s,

t h e si ze c o n t e n t o f w h i c h i s o f te n n o t k n o w n . T a b l e 3 .2 s u m m e r i s e s t h e n e c e s s a r y

c ond i t i ons fo r de s i z i ng s t a r c h i n p r e s e nc e o f s ome i mpor t a n t ox i d i s i ng a ge n t s .





De s iz ing 7 7

A l k a l i n e p e r o x y c o m p o u n d s [ 1 3 , 1 4 ] h a v e b e e n f o u n d m u c h m o r e s u i t a b l e f o r

the e f f e c t ive ne ss a s de s i z ing a ge n t . Pe r ox ym ono su lph ur i c a c id (H2S O5), sod iumpers ulp ha te , p e ro xy disu lph a tes [NazS208 , K2S20 s and (NH4)2S208] , ac id h yd rog en

p e r m o n o s u l p h a t e s ( K H S O 5 a n d N H 4 H SO s ) a n d p o t a s s i u m p e r o x y d i p h o s p h a t e

(K 4P 2O s) h a v e b e e n s h o w n t o be e f f e c t i v e f o r d e s i z i n g [ 1 5 - 1 9 ] .

Pe r o xy m on osu lphu r i c a c id (2 g / l) is a pp l i e d in a s im i l a r m a nn e r to tha t o f m ine r a l

a c id d e s iz i n g . P e r s u l p h a t e s ar e r e c o m m e n d e d f o r a m b i e n t t e m p e r a t u r e d e s i z in g

c on ta in ing 0 .5% pe r su lpha te , 0 .5% te t ra sod ium p yr oph osph a te a nd 0 .5 - 3% c a us t ic

soda wi th 4 - 8 h t r e a tm e n t tim e . Pe r pho spha te r e qu i r e s a h igh e r t e m pe r a tu r e f o r

a c t iva t ion tha n doe s pe r su lpha te , i t i s u se d m or e f r e que n t ly in c a us t i c s a tu r a to r

be c a u se o f i ts s t a b i li t y a t e l e va te d t e m pe r a tu r e s . Pe r pho spha te a l so e xh ib i t s a syn -

e r g i s t ic e f f e c t on the c a us t i c t r e a tm e n t o f the f a b r i c a s e v ide nc e d by the lowe r so l-

ve n t e x t r a c t ib i li t i e s a nd the c l e a ne r bo t tom . The ino r ga n ic pe r sa l t s v iz . sod ium

pe r bor a t e ( Na B O 3. 4H 20 ) a nd sod ium c a r bona te hyd r oge n pe r ox ide ( 2Na 2C O 3.

3H202) ha ve b e e n show n to be e f fe c t ive in f oa m de s i z ing a n d b le a c h in g o f ya r n

a nd d ye d f a b ri c .

The m a in l im i t a t ions o f ox ida t ive de s i z ing a ge n t s a re inc r e a se d po l lu t ion loa d ,f ib r e da m a ge a nd ina b i l i t y to r e c ov e r a nd r e - use wa te r so lub le s i z es . Ox id a t ive

de s i z ing a ge n t s r e qu i r e p r e c i se c on t r o l on p r oc e ss pa r a m e te r s . M e ta l s c a t a lyse the

a c t ion o f ox id i s ing a g e n t s a nd the de s i z ing l iquor shou ld no t be in c on ta c t w i th a ny

m eta l f i t t ings .

3 .3 D e s i z i n g o f S y n t h e t i c F i b r e F a b r i c s a n d T h e i r B l e n d s w i t h C e l lu l o s e

T h e m o s t c o m m o n s i zi n g a g e n t s u s e d f or n y l o n a r e b a s e d u p o n P V A , g e la t in ,

c a se in o r va r i e ty o f ve ge ta b le a nd m ine r a l o i ls . De s iz ing o f r e ge ne r a t e d c e l lu lose s

de pe n ds on na tu r e o f si z e tha t m us t be r e m o ve d . De s iz ing i s d i f f ic u l t a s r a yon

swe l l s i n wa te r to a g r e a t e x te n t . Th i s l e a ds to poo r pe ne t r a t ion o f e nz ym e .

W h e n w a t e r s o l u b l e P V A i s u s e d a s s i z i n g a g e n t i n w e a v i n g , n o d e s i z i n g o f

syn the t i c f ib r e f a b r ic s is ne c e s sa r y . L igh t s c our ing wi th non - ion ic su r f a c t a n t

(3-5 g / l ) a t 95-100~ for 20-30 ra in is eno ug h to rem ov e the s iz ing m ate r ia l . How -

e ve r , h igh m ole c u la r we igh t PV A a b ove 1 ,00 ,00 0 a r e found to be qu i t e d if f i cu l t t o

r e m ove f r om the f a b r ic du r ing de s i z ing a nd r e su l t s in une ve n de s i z ing .

Po lye s t e r s i z ing a ge n t s ar e no t r e m ove d by s im p le wa sh ing t r e a tm e n t . S u i t a b lede te r ge n t s f o r r e m ov ing po lye s t e r s i z e a re the e f fi c i e n t a n ion ic o r non - ion ic type s





Des iz in g 79

3 .4 D e s i z in g M a c h i n e r i e s

T h e d e s i z i n g p r o c e s s e s a r e v e r y m u c h d i c ta t e d b y e c o n o m i c s i n t e r m s o f t h ech em ica l o r en zy m e co n s u m p t io n , t h e eq u ip m en t av a i l ab le an d t h e en d u s e r eq u i r e -

m e n t s . W i t h th e i n t ro d u c t i o n o f J - B o x e s a n d o t h e r c o n t i n u o u s p r e p a r a t o r y m e t h -

o d s an d eq u ip m en t , d e s i z in g i s g r ad u a l ly l o o s in g i ts i d en t it y a s a s ep e r a t e p r o ces s .

N o w - a - d ay s d es i z in g an d s co u r in g can b e ca r r i ed o u t i n o n e o p e r a t i o n an d t h u s a

s u b s ta n t ia l a m o u n t o f t im e a n d e n e r g y c a n b e s a v e d. T h i s h as b e c o m e p o s s i b l e

m a i n l y b e c a u s e o f m a n y m i l d o x i d i s i n g a g e n t s c a n b e a d d e d t o c o n v e n t i o n a l l i q u o r

to p r o m o te d e s i z in g , w h i l e th e s co u r in g is i n p r o g r es s . S im u l t an eo u s d es i z in g an d

scour ing can a l so be car r ied ou t in k ier s by a jud ic iou s cho ice o f chem ica ls . De s iz ing

in th e b a t ch p r o c es s can b e ca r r i ed o u t i n a j i g o r w in ch o r i n a k i e r p r io r t o b o i l- o f f.

F o r s m a l l l o ts , f o r ex am p le o f t h e o r d e r o f 1 000 m o r l e s s d es i z in g can b e ca r r i ed

o u t i n j i g s o r r o p e w as h in g m ach in es . Co m p r eh en s iv e d ev e lo p m en t o f m ic r o p r o s s o r

t ech n o lo g y en ab l e s j i g g e r s (F ig . 3 - 6 ) t o b e co n n ec t ed t o a p e r s o n a l co m p u te r . E v -

F ig u r e 3 - 6 . Un iv e r s a l J i g g e r f o r p r e - t r ea tm en t p r o ce s s es

( C o u r te s y o f B e n n i n g e r A G , U z w i l ).

e r y s t ag e o f t h e p r o ces s can b e g r ap h i ca l l y d i s p l ay ed o n t h e p e r s o n a l co m p u te r .

T h e m o d e m m a c h i n e i s s u p p l i e d w i t h b a t c h i n g u p f a c i l i t i e s , a u t o m a t i c s e l v e d g e

s h i f ti n g , au to m a t i c t en s io n r eg u l a t i o n an d g en t l e h an d l in g o f e la s t i c i s ed o r u l tr a -

d e l i ca t e f ab r ic s . T h e en t i r e p r o d u c t io n d a t a , f ro m lo ad in g t h e f ab ri c , d e s i z in g ,

w a s h in g an d u n lo ad in g e t c . c an b e p r in t ed o u t. I f en zy m e t r ea tm en t i s ca r r i ed o u t

in w in ch o r s im i l a r d y e in g m ach in e (F ig . 3 - 7 ) in f o r m o f r o p e , d es i z in g m ay b ec a r r ie d ou t a t 6 0 -7 0 ~ f o r 3 0 m i n w i th r e d u c e d a m o u n t o f e n z y m e . T h e m o d e m



80 Des iz ing

rope wash ing mach ines can be used fo r p roces s ing wi th any k ind o f f ab r i c wi th

redu ced w ater consum pt ion , chem icals and e lec t rica l energy. The fabr ic i s pro-

Figure 3-7 . Ma chine for des iz ing and wash ing in the rope fo rm

[Courtesy Cimi S.R.L, (Biel la) , I taly] .

pel led by a w inch in conjunc t ion wi th good mi l l ing ef fect. The fabr ic capaci ty of

the mach ine i s abou t 350 kg wi th max imu m speed o f abou t 600 m/ min .

In the batch process (Fig . 3-8) long d iges t ion t ime in the range of 6-16 h are. . . . . | | | l | l - - , m | i _ . | |l i i | m _ , _

I

I

I|

It

Singer Satura tor Batch

F igure 3 -8 . S chemat i c d i ag ram o f pad -ba t ch sys t em show ing s inger ,

des ize sa tura tor and padder . (C our tesy o f Ju l ien S .A, Belg ium ).

g iven becau se the ma ter ia l is unheated . After imp regnat ion w i th the so lu tion con-

ta in ing des iz ing agent , non-poisoning wet t ing agent and sa l t , the fabr ic in open

wid th fo rm is ba tched and covered w i th po ly thene shee t t o p reven t f ab r i c be ing

dr ied une ven ly [24] . The sa tura tor a lso works as a quench bo x in wh ich a l l sparks

are ext inguished imm ediate ly af ter s ingeing the c lo th .





8 2 De s iz ing

F igur e 3 - 11 . C o n t inuous a u tom a t i c s t e a m ing c ha m be r .

sa tu r a t e d s t e a m f o r 20 - 6 0 se c onds . The bo t tom o f the s te a m ing c ha m be r i s p r o -

v ide d w i th s t e a m r a d ia t ing p ipe s to ob ta in the ne c e s sa r y c o nd i t ions o f t e m p e r a tu r e

a nd hum id i ty . A lka l ine pe r ox ide i s g r e a tly u se d in c on t inuous pa d - s t e a m p r oc e sse s

[ 26 ] in w h i c h d e s i z in g , s c o u r in g a n d b l e a c h i n g c a n b e c o m b i n e d . W h e n e n z y m e s

a r e a pp l i e d to s t a r c h the e nz ym e se n s i t iv ity to he a t i s r e m a r ka b ly im p r ove d i f t he

e nz y m e c a n be a pp l i e d fi r st a nd the n s te a m e d . Af te r de s i z ing is c om ple te d the

f a b r i c i s wa she d in a n ope n wid th wa she r ( F ig . 3 .12 ) to r e m ove the sho r t c ha in

F i g u r e 3 - 1 2 . O p e n w i d t h w a s h e r ( C o u r t e s y o f F a rm e r N o r t o n ).

suga r s be c a use the se a r e wa te r so lub le. The w a she r i s spe ci f ic a l ly de s igne d to m e e t

the c u r r e n t de m a nd f o r g r e a te r e ne r gy sa v ing a nd i s to t a l ly e nc lose d a nd in su la t e d .

I f J - B o x ( F ig . 3 - 13) i s u se d f o r de s i z ing o f c o tton f a b r i c in c on t inuou s o pe r a t ion , a

t e m pe r a tu r e r a nge o f 6 0 -9 0 ~ f o r 15 - 20 m in wi l l su f fi c e. The use o f h igh p r e s su r e





84 Desizing

The ICI Marka l p rocess i s used fo r des iz ing and scour ing by us ing suspension o f

enzy m e in t r ich loroe thy lene and sur fac tan t so lu t ion . The fabr ic is padd ed th roughthe so lven t fo rmula t ion , s teame d to remo ve the so lven t and to ac t iva te the enzym e.

A wa sh -of f wi th water comp le tes the p rocess . The Marka l p rocesses a re su i tab le

for po lyes te r /co t ton , po lyes te r / rayon and o ther b lends as wel l as fo r co t ton .

R E F E R E N C E S

1 E .G.V. and E . Perc iva l , S t ruc tu ra l Carbohydra te Chemis t ry , Garne t Mil le r ,

London , 1962 .

2 J. Hon eym an, Recent Advan ces in Ch em istry of Cellulose and Starch, Ch apm an

and Hal l , London , 1959.

3 R. G. Fargher , L. R. Hart and M. E. Prober t , J . Tex ti le Inst . , 18 (1927) T 29.

4 R. E. Hu dso n and H. M. W add le, Texti le Res. J ., 18 (1948) 232.

5 H . M. Le ice s t e r, Dev e lo p m en t o f B io ch em ica l Co n cep t s f r o m An c ien t t o

M od em Tim es , Harvard Univers i ty Press , Cam br idge , Mass , 1974 , p 166.

6 P . D. Boyen , H. A. Lardy and K. Myrback , The Enzymes, 2nd Ed . , Acad .

Press , N ew York , N. Y., 1953 .

7 N. K. Lange , Tex ti le Ch em . Color . , 29 (6) (1997) 23.

8 E. Schubert , Texti l -Rundschau, 5 (1950) 1 .

9 E . Schuber t , Tex t i l -Ru ndscha u , 3 (1948) 295 ,335 .

10 R. E. Ye lin and Vil l iers , Texti le Chem . Color . , 4 (1972) 50.

11 R .L . Holb rook e t a l ., Am er . Dy estu f fR ep . , 53 (3) (1966) 88.12 R. Freytag , Tein tex, 25 (1961) 323.

13 K. Dickso n, J. Soc. Dy ers Colou rists , 95 (1979) 11 9.

14 K. Dickso n and J . J . Tho m son , Am er . Dye stu f f Rep . , 69 (1980) 9.

15 N. Ob yabu , Japan Tex t i le Ne ws, (M arch 1977) 52 .

16 L. Chemer, J . Soc. Dyers Colourists , 19 (1963) 139.

17 W . A. S. W hite , N. J . Ro ss an dN . F. Crow der , J. Tex ti le Inst . , 50 (1959) 3 .

1 8 E . J . d u P o n t , P r o d u c t B u l l e t i n N o . A - 6 9 7 4 2 , " O x o n e M o n o s u l p h a t e

C o m p o u n d " , A p ri l 1 97 0.



Desiz ing 85

19 L. A . S i tver , K. E . Be rnard and R. E . Yel in , F . M. C. Co rporat ion , "E ffe ct o f

P o t a s s iu m P e r p h o s p h a te o n P e r o x id e B l e a c h i n g " .20 E. S. Ols on and Lyo ns, Text i le Res. J. , 42 (1972) 1 99.

21 Krav etz , Te xt i le Che m. Co lor ., 5 (1973) 29.

22 Jones , AA TC C S ym pos ium : 'Tex t i le S o lven t Te chn o log y ' , J an 1973, p 103.

23 V. G. S toko zenk o, S . M. Gub ina and V. N. Galashina , Pefera t . Zhur . , 12 B

(Dec 1987) 12.

24 I . Re gan , J . Soc. Dy ers Co louris ts , 78 (1962) 533.

25 J. A. D. Ha ll, D ye r 125 (196 1) 727.

26 Row e, Tex t i le Chem . Color ., 3 (1971) 170.

27 Shipm an, Sou th Afr ican Text i les , (Sept 1970) 32 .





S c o u ri n g ~ , ~ 8 7

sorbs a lka l i . Alka l i neu t ra l i ses the carboxyl g roup in ce l lu lose and in pec t in . The

h y d ro x y l g ro u p s o n t h e g l u co s e u n i ts i n ce ll u l o se a r e a l s o w eak l y ac i d ic . O w i n g t oth i s p referen t i a l so rp t ion , the concen t ra t ion o f a lka l i in the f ib re i s increased and

thus a t t acks the im pur i t i es more in tens ive ly .

4 .2 M e c h a n i s m o f R e m o v a l o f I m p u r i t i e s

Th e ac t ion of alkal ine scou ring agen t i s to saponify any res idual o i ls, to neutral ise

carbo xyl ic ac ids , to so lub i l i se any s iz ing mater ia l s and to cause d i spers ion o f na tu -

r a l l y o ccu r i n g i mp u r i t i e s i n n a t u ra l f ib r e s. T ab l e 4 .1 s u m m er i s e s t h e r emo v a l p ro -

cess invo lved dur ing scour ing .

T A B L E 4 . 1 .

T ech n i q u es fo r Re m o v i n g N a t u ra l Imp u r i t i e s o f Co t t o n D u r i n g Sco u r i n g [ 1

I m p u r it ie s M e t h o d o f r e m o v a l

F a t s an d w a x es

P ec t i n s an d r e l a t ed s u b s t an ces

M i n e r a l s a n d h e a v y m e t a ls

A m i n o ac i d s o r p ro t e i n s

Lubr ican t s /Kni t t ing o i l s

Lev e l s a r e r ed u ced t o acce p t ab l e l i mi t s b y t h e

ac t ion o f a lka l i and sur face a c t ive p roduct s , in

ex t r eme cas e s th e u s e o f s o l v en t an d s u r f ac tan t

m i x t u re s may b e n eces s a ry .

So lub i l i sed by the ac t ion o f a lka l i, usu a l ly caus t i c

soda, which also acts as a swel l ing age nt to faci l ita te

r emo v a l .

(a ) By p rodu cing m ore so lub le sa l t s e.g . ac id

dem inera l isa t ion (b) By use o f sequ es te r ing agen t s.

So l u b i l is ed b y p ro d u c i n g co r r e s p o n d i n g s o d i u m

salt.

M o d em mi n e ra l o i l f o rmu l a t i o n u s u a l l y co n t a int h e ir o w n s e l f - emu l s i f ica t i o n s y s t em.

Na tura l fa t s , o i l s and lubr ican t s ( t a l low) a re mos t ly es te rs usua l ly in the fo rm of

t r ig l y ce r i d es . Be i n g t r ig l y ce r i d es , t h e l u b r ican t s can b e a l mo s t h y d ro l y s e d b y l i-

pases , y ie ld ing g lycero l , fa t ty ac ids and mo no-a nd d ig lycer ides as the reac t ion p rod-

u c t. G l y ce ro l i s co m p l e t e l y w a t e r s o l u b le , f a t ty ac i d is r emo v ed d u r i n g s co u r i n g

an d mo n o an d d i g l y ce r i d es a r e k n o w n t o b e e f f i c i en t s u r f ac t an t s o r emu l s i f i e r s .

Thus , a l ipase t rea tm ent im prov e no t on ly des iz ing bu t a lso the sco ur ing p rocesses .T h e e s t e r s r eac t w i t h s o d i u m h y d ro x i d e t o fo rm s o ap an d g l y ce r in e . T h e s o ap th u s







9 0 S c our i ng

4 . 3 .3 T h e s o d a - a s h b o i l

The t ype o f a l ka l i u s e d fo r s c our i ng o f c o tt on de p e nds on t he qua l i ty o f goods .For e x a m pl e , i f c o l ou re d y a rns p r e s e n t i n the f a b r ic , s od i um c a rbona t e i s i de a l ly

s u i t e d be c a us e o f i t s l ow pH . C o t t on ya rns t o be dye d i n da rk s ha de s hou l d be

s c o u r e d w i t h 1 - 2 % s o d i u m c a r b o n a t e s o lu t io n f o r 30 m i n i n p r e s e n c e o f w e t t i n g

agent .

4 . 3 . 4 T h e m i x t u r e o f c a u s t i c - s o d a a n d s o d a - a s h b o i l

A c om bi na t i o n o f 2 pa r t s o f c a us t i c s oda a nd 1 pa r t o f s od i um c a rbona t e i s

o f t e n us e d i n s ing l e s t a ge bo il ing . S oda -a s h s o f t ens t he w a t e r w h i l e i n t e r a c t i ng w i t h

C a a n d M g s a lt s ( i f s uc h a r e p r e s e n t ) ; i t c r e a t e s a n a c t ive r e a c t i on o f t he me d i um

w h i c h i s m os t f a vo ura b l e fo r t he fo rma t i on o f s t a b le e mu l s i ons a nd s us pe ns i ons ;

i nc r e a s e s f i b r e s w e l l i ng , t hus c on t r i bu t i ng t o t he r e l e a s e o f i mpur i t i e s f rom t he

f i b re ; ne u t r a l i s e s f a tt y a c ids c on t a i ne d i n t he f a b r ic by s oa p fo rm a t i on ; obv i a t e s

s oa p hyd ro l ys i s i n t he p r e s e nc e o f w o o l ; r e duc e s t he a dhe re nc e o f de t e rge n t s t o

w o o l i n th e a l k a l in e m e d i u m c o n d i ti o n s .

4 . 3 . 5 T h e s o a p / d e t e r g e n t - s o d a - a s h b o i l

T h i s c o m b i n a t i o n i s c o m p a r a b l y m i l d e r c o m b i n a t i o n t h a n th a t o f c a u s ti c s o d aa nd he nc e i de a l l y s u i t a b l e fo r more de l i c a t e c l o t hs a nd c o l ou r w ove n goods c om-

pe n s a t i ng fo r the s l ow e r a c t i on o f the m i l de r a l ka l i by t he a dd i t i on o f a de t e rge n t .

A n i on i c p roduc t s l i ke s od i um a l ky l s u l pha t e s a nd a l ky l a roma t i c s u l phona t e s a nd

non- i on i c s l i ke po l ye t hoxy l a t e d c om pou nds a r e u s e d a s de t e rge n t. S om e t i me s m i x -

t u r e s o f a n i on i c a nd non- i on i c p rod uc t s a r e u se d . I t i s pos s i b l e t o ob t a i n a s yne rg i s -

t i c e f f e c t be t w e e n a de t e rge n t a nd a l ka l i , s o t ha t t he t w o a ge n t s w he n c ombi ne d

increase the i r to ta l ac t iv i t i e s ra the r than inhib i t each o ther . F ig . 4-2 shows the syn-

~v-- i ~ ~ f ~ j ~ j ~...9 0 - - -

8 0 . - - - _.~

70 . . . .

60 . . . .

~ 5 0 _

4o 11

73 0 , . -

2 0 - -

_. I .1 1 I I .1 i I ~ l . _ _ . . d ~

100 19~0 80 70 60 5 0 ~ ] 30 20 10 0% ST P

0 20 30 40 50 70 80 90 100 % Alkyl arvl

Detergen r ion suifonate

Fi gu re 4 -2 . E f f e c t o f s o 'd i um t r i po l ypho s pha t e ( S TP) on de t e rge n c y [ 4 ].



Scouring 91

erg is tic e f fec t when phosp hates a re com bined w i th a lky l a ry l su lphonates and a re

used as scour ing agen ts in p rocess ing water . Af te r scour ing , w ash ing i s car r ied ou tby ho t p rogress ive r ins ing w hi le g radua l ly decreas ing the tempera tu re in o rder to

avo id b reak d ow n of the em uls ion and prec ip i ta t ion o f the impur i t ies on to the co t -

ton . W ash in g i s com ple ted by t rea t ing the fabr ic in an ac id so lu t ion to neu t ra l ise

any alkal i re tained b y the fabr ic .

4.3.6. Sequestering agents

Seque ste r ing agen ts o r che la t ing agen ts a re nega t ive ly charged and a re capab le

of fo rming s t rong r ing s t ruc tu res (F ig . 4 -3) wi th the meta l ions p resen t in hard

/ C H 2 C H 2 ~

HO ?OH2 H N ~ H ~

/?% ~ ' /~~ 2+ ~ -~u2, / + 2H2N CH2CH2NH2 --~ / Cu, / + 4H20

U20 / ~ ~ O / U 2 H2N/~ ~/NH2" ~ 2 2 C H ~ / ~

Figure 4 -3 . A typ ica l che la te s t ruc tu re (Cou r tesy o f Do w C hem ica l Co . ) .

wa ter and in pec t ins o f co t ton . The pos i t ive ly charged meta l ions, par t icu la r ly Fe3+and C a 2+ are read i ly ava i lab le fo r reac t ion wi th any neg a t ive ly charged an ion such

as OH- or CO3-2 and inso lub i l i se soap in the f ib re which m ay d is tu rb subsequen t

opera t ion . Th is p rob lem is m uch m ore acu te when scou r ing is carr ied ou t in con-

t inuous p rocess invo lv ing padding ba th where l iquor ra t io is m uch lowe r than the

batc h proces s [5] . Thus , the functions of the chelat ing agen ts in the soap and deter-

g en t f o rm u la t io n s a r e f o r t h e p r ev en t io n o f -

i ) f i lm and scum format ion ,

i i) p rec ip i ta t ion o f hard water ,

i ii ) ca lc ium and m agn esium inh ib i t ion o f foam ing proper t ies ,

iv ) c logg in g of l iqu id d ispers ions ,

v) haze turbid i ty in l iquid solut ions, and

vi) ranc id i ty and ox ida t ion tha t cause d isco loura t ion o f fo rmula t ion .Sequeste r ing power i s in f luenced by pH of the scour ing ba th . At a g iven pH,



92 Scouring

different amount of chelating agents are required to chelate a given amount of

metal. O rganic sequestering agents that find com mercial uses (F ig. 4-4) are stable

O OII II

N a O - C - C H 2 \ / C H 2 - C - O N a

N- CH2- CH2- N

N a O - C -C H 2 / \ C H 2 - C - O N aIIO O

/ C H 2 - C O O HN - C H 2 - C O O HN

CH2-COOH

HOOC CH2 "xN_CH2__CH2_N/CH2COOH

HOOCCH2 \CHzCOO H

Et hy l ened i ami net e t r aace t i c Ac i d(EDTA)

N i t r i l o t r i a c e t i c

Ac i d and Sa l t s(NTA)

N-(2-Hydroxyethyl)e t h y l e n e d i a m i n et e t r aace t i c Ac i d(HEDTA)

HOOCCH2\ /CH2COOH

N-CH2-CHa-N-CH 2- CH2-NHOOCCH2 / CHaCOOH \CH 2C OO H

D i e t h y l t r i a m i n ePentaacet ic Acidand Salts (DTPA)

HO-CH2-CH 2 \ OII

N - C H 2 - C - O N a

HO_CH2_CH 2 /

N , N - D i

(2-Hydroxyethyl)Glycine (DHEG)

HOOC-CH2N NCH2_CH_CH2N~ %H2COOH

/H O OC -C H 2 OH C H 2 C O O H

Diaminopropanoltriacetic Acid(DPTA)

Figure 4-4. Am inocarboxylates and hydroxy carbox ylates

as organic sequestering agen ts.to hot alkaline scouring solutions. There are som e organopho sphonates (Fig. 4-5)



S c our ing 93

H203P-H2C \ /CH2-PO3H2

NI

CU2-PO3U2

O HI

CH3-C-PO3H2

~O3H2

A m i n o t r i - ( m e t h y l e n e

p h o s p h o n i c a ci d ) A T M P

1-Hy droxy e thyleden e- 1 , 1-

d iphospho n ic a c id ( HEDP)

H203P-H2% /CH2-PO3H2N-CH2--CH2-N

H203P-H2C NCH2_PO3H2

Ethylen ediam ine tet ra -(me-t h y l e n e p h o s p h o n i c a c i d )

( E D T M P )

Die thy le ne

H203PH2C N / CH2PO3H2 t r i a m inope n ta -

N-CH2-CH2- N-CH2- CH2-N (methylene

HzO3PH2C / CH 2 xX CH2PO3H2 p h o s p h o n i c

PO3H2 a c id ) ( DTM P)

F i g u r e 4 - 5 . C o n s t i tu t i o n o f o r g a n o p h o s p h o n a t e s e q n e s t e r in g a g e n t s [ 6 ].

wh ic h , how e ve r , a c t a s a s e que s t e r ing a ge n t a nd a t t he sa m e t im e c o n t r ibu te to

de te r ge nc y , d i spe r s ing p r ope r t i e s a nd p r e ve n t so i l r e de pos i t ion on t e x t i l e goods .

Ho w ever , the produ c ts a re not s tab le in a lka li so lu t ion a t h igh tem pera ture . A t h igh er

t e m p e r a t u r e s t h e y a r e h y d r o l y s e d t o o r t h o p h o s p h a t e w h i c h h a s n o d i s p e r s i n g a s

we l l a s s e qu e s t e r ing p r ope r t i e s .

4 . 3 . 7 B u i l d e r s

B u i lde r s a r e ge n e r a l ly a dde d to the k i e r bo i l ing ba th to inc r e a se the a c t iv i ty o f

soa p o r de t e r ge n t s . B u i lde r s a r e ge ne r a l ly s a l t s suc h a s bo r a t e s , s i l i c a t e s , phos -

pha tes , sod ium chlor ide , sodium sulpha te e tc . Sod ium m etas i l ica te (Na2SiO 3. 5H2 0)

a l so a c t s a s a de t e r ge n t a nd bu f f e r a nd a s s i s t s o the r c he m ic a l s to pe ne t r a t e in to the

l ign in m a ss o f c e l lu lose m a te r i a l s. I n ge ne r a l, t he f unc t ion o f the bu i lde r s i s t o d r ive

the soa p f r om w a te r pha s e to fa b r i c /wa te r i n t e r f a c e a nd c on se qu e n t ly inc r e a se the

c on c e n t r a t ion o f soa p on the f a b r i c . I t i s ine xpe ns ive , bu t i t s a dd i t ion in the sc our -ing ba th inc r e a se the a sh c on te n t o f c o tton .



94 Sco u r in g

4 .3 . 8. F i b r e p r o t e c t i n g r e d u c i n g a g e n t s

So d iu m h y d r o x id e s o lu t i o n d u r in g k i e r b o i l i n g o f co t t o n a t h ig h t em p er a tu r ec a n f o r m o x y c e l l u lo s e i n p r e s e n c e o f o x y g e n . G e n e r a ll y , o x y g e n is r e m o v e d f r o m

th e k i e r b e f o r e s co u r in g s t a rt s , b u t ev en a s m a l l q u an t i ty o f a ir en t r ap p ed i n th e

f ab r ic l ay e r s m ay cau s e p r o b l em s an d t en d e r in g o f c lo th t ak es p lace . T h u s , a s m a l l

q u an t i t y o f m i ld red u c in g ag e n t s u ch a s so d iu m b i s u lp h i t e o r ev en h y d r o s u lp h i t e i s

ad d ed t o t h e k i e r l i q u o r t o p r ev en t o x id a t i o n o f ce l l u lo s e d u r in g s co u r in g o p e r a -

tion.

4 . 3 .9 M i l d o x i d i s i n g a g e n t s

So m et im e s , w o v en f ab ri c co n t a in s a v a t o r azo i c d y ed co lo u r ed y a r n t o h av e a

s t r ipe e f f ec t . W he n such f abr ics a re scoured in a p ressu re k ier und er a lka l ine cond i -

t io n , t h e r e i s a lw ay s a r i sk o f s ta in in g t h e ad j acen t w h i te g r o u n d b y b l eed in g o f d y es

f r o m th e co lo u r ed t h r ead . Azo ic d y es m ay b e m ech an ica l l y t r an s f e r r ed w h i l e t h e

v a t d y es m ay b e r e d u ce d t o i ts s o lu b l e l eu co s ta t e i n p r e s en ce o f a lk a l i an d im p u r i -

t i e s r em o v ed f r o m th e c lo th . F o r s u ch t y p es o f f ab r i c s m i ld o x id i s in g ag en t s l i k e

Lu d ig o l , Re s i s t Sa l t L e tc . m ay b e ad d ed t o th e s co u r in g b a th t o r e s is t th e r ed u c in g

p r o p e r t i e s o f d y es . Ch em ica l l y , t h e s e p r o d u c t s a r e s o d iu m s a l t o f n i t r o b en ze n esu lphonic ac id. A l te rna t ive ly , such f abr ics con ta in ing co loured th reads can be scoured

in o p en k i e r , o n w in ch m ach in e , j i g g e r o r co n t in u o u s m ach in e w i th b o i l i n g s o d a -

a s h l i q u o r (2 . 5 % o . w . f .) i n s t ead o f cau s t i c s o d a t o r ed u ce t h e m a r k - o f f t o a m in i -

m u m .

4 . 3 .1 0 W a t e r i n s o l u b l e s o l v en t s

F o r t h e p u r p o s e o f acce l e r a t i n g t h e s co u r in g p r o ces s , w e t t i n g ag en t s a r e s o m e-

t i m e s u s e d i n c o n j u n c t i o n w i t h h i g h b o i l i n g s o l v e n t s ( c y c l o h e x a n o l ,

m e th y l cy c lo h ex an o l , t e t r ah y d ro n ap h th a l en e , d ecah y d r o n ap h th a l en e e tc .) . T h e f u n c -

t i o n o f t h e s o lv en t i s t o d i s s o lv e m o r e i n s o lu b l e f a t s an d w ax es an d t h a t o f t h e

d e t e r g en t t o em u l s i f y t h e s o lv en t an d w ax es .

4 . 4 S u r f a c t a n t s

A s u r f ac t an t m a y b e d e f in ed a s a su b s t an ce w h ich , w h en ap p l i ed in lo w co n cen -

t r a t io n , m ar k e d ly r ed u ces t h e s u r f ace t en s io n o f a s o lv en t . A g o o d s u r f ac t an t , f o r

ex am p le , w i l l r ed u ce t h e s u r f ace t en s io n o f w a te r f ro m 72 d y n e s / cm to 3 0 d y n es /

cm a t a co n cen t r a t i o n o f l e s s t h an 0 . 1 %. T h e co n cen t r a t i o n a t w h ich n o f u r th e rr ed u c t io n i n s u r f ace t en s io n o ccu r s i s k n o w n as ' c r i t i c a l m ice l l e co n cen t r a t i o n ' .

Gen e r a l l y , s u r f ace t en s io n b e tw een t ex t il e f i b re s , p a r t i cu l a r ly s y n th e t i c f i b r e s an d



Scour ing 95

wa ter i s h igh , and hence we t t ing o f the f ibre surface does not take p lace tho roug hly

and quickly. Surfactants reduce the interfacial tension and thereby bring ab out quickwet t ing of the f ibre surface . Surfactants are widely used in scour ing of synthet ic

f ibres which do not conta in natura l ly occur ing impur i t i es l ike cot ton . Surfactants

are a l so used in wool scour ing and a l so ass i s t in the mi l l ing and development of

wool len fabr ic .

A high qual i ty synthet ic detergen t provides a good balance w i th wet t ing , c lean-

ing, emulsifying, dispersing and foam ing properties , thus providing i t a good cleaning

abi l i ty . Chemical ly , the surfactants are long chain organic compounds conta in ing

bo th a hydrophob ic and a hydroph i l i c componen t . The hydrophob ic cha rac t e r i nthe surfactant molecu le i s associa ted w i th the hydrocarb on chain , usual ly qui te long

in i ts l ength . Al thou gh lowe r ing o f surface tens ion i s an essent ia l req ui rem ent of a

good su r fac t an t, t he com poun d shou ld have p roper hydrophob ic l yoph i li c ba lance

(HLB ) to have balanced wa ter so lubi li ty and water insolubi li ty . Surfactants m ay be

class i f ied in to four groups , v iz . an ionic , ca t ionic , non- ionic and am photer ic surfac-

tants . However , the non- ionic and anionic detergents and b lends , so lvent ass i s ted

detergen t b lends , soaps and pH buffered 'bu i l t p rod ucts ' a re m ainly used for scour-

ing in text i le industry.

4 . 4 . 1 A n i o n i c s u r f a c t a n t s

Anion ic su r fac tan t s a re those w h ich bea r a nega t i ve charge and m ig ra t e t oward

the anode or pos i t ive ch arge in so lu t ion . Th is c lass of sa l t l ike com pou nds include

the soaps and m any of the pop ular syn thet ics (Fig . 4-6) . W hen fa t s are hydroly sed

Anionic detergent Che mical s t ructure

Sodium s teara te (soap)

Dip ropy le naph the l ene su lphona t es

Alky l benzene su lphona t es

Alkyl su lphatesAlkane su lphona tes

Phosphate es ters

C I7H35C O O Na

3 7 * s o 3 aC ! 2 H 2 5 ( ~ , ~ 83 N a / / ,

C H 3- (C H 2) 16-CH2OSO3NaC I7H33COOCHCH2SO3Na

Igepon A

C 7H33CO-N-C2H4SO3Na1 C ~ . . _ ~ 3

Igepon T

R - O - ( C 2H O )x-PO 3Na2R = Octyl or non yl pheno l or fa t ty a lcohol

Figure 4-6 . Ty pical exam ples o f an ionic detergents .



9 6 S c our i ng

i n p r e s e n c e o f a lka l i f at ty a c i d i s f o rm e d w h i c h on ne u t r a l is a t i on w i t h c a us t ic s oda

fo rm a s od i um s a lt o f f a t ty a c id , know n a s s oa p . The m os t i mpo r t a n t f a c t o r w h i c h

de t e rm i ne s t he p rope r t i e s o f s oa p is t he num be r o f c a rbon a t oms i n t he a l ipha t i c

soap. Soa p wi th h igh m olec ula r w e igh t (C~2 to C~8 i s only su i t ab le for use w hen

s c our i ng c a n be c a r r i e d ou t a t o r ne a r t he bo i l i ng po i n t o f t he s o l u ti on . T he i n s ta b i l -

i ty o f s oa p i n ac i d s o l u t ions i s t he ma i n d r a w ba c k . S yn t he t i c de t e rge n t s a r e s u r fa c -

t a n t s de ve l op e d t o ove rc o m e t he d r a w ba c k s o f s oa ps . The y a r e sa l ts o f s t r ong a c i ds

and w he n p ure they a re prac t i ca l ly neu t ra l . In cont ras t to soap they a re l e s s li ab le to

ha rd w a t e r p r e c i p i t a t i on a nd a r e r e a d i l y ri n s a b l e .

I n t he l a t e 19 20 ' s l ong c ha i n f a t t y a l c oho l s w e re s u l phona t e d a nd s o l d a s

ne u t r a l i s e d s od i um s a lt s. In 1 9 30 ' s l ong c ha i n a l ky l a ry l s u l phona t e s w i t h be nz e ne

a s a rom a t i c ne uc l e a s a nd a l ky l po r t i on m a de f rom ke ros i ne po r t i on a ppe a re d on the

m a rke t i n U . S . A . B o t h t he a lc oho l s u l pha t e s a nd tr i a lky l a ry l s u l phon a t e s w e re s o l d

a s s u c h a s c l e a n in g m a t e ri a ls b u t d i d n o t m a k e m u c h h e a d w a y o n t h e to t al m a r k e t .

I n 1 9 4 0 ' s, d o d e c y l b e n z e n e , f o r m e d b y t h e r e a c ti o n o f p r o p y l e n e t e t r a m e r w i t h

b e n z e n e , w a s a v a i l a b le i n p l e n t y a n d d o d e c y l b e n z e n e s u l p h o n a te d o m i n a t e d t h e

s yn t he t i c de t e rge n t m a rke t . L a t e in 19 50 ' s , h i ghe r m o l e c u l a r w e i gh t m a t e r i a l s w i t ha n a ve ra ge o f 13 c a rbon a t oms i n s t e a d o f 12 a s i n dode c y l be nz e ne w a s found t o

hav e be t t e r de te rgen cy. In the ea r ly 60 ' s , i t was found tha t the bran che d cha in s t ruc -

t u r e o f dod e c y l b e nz e ne s u l phona t e s a r e no t b i od e gra d a b l e a nd t hus li ne a r a lky l

be nz e n e s u l phona t e ha s r e p l a c e d p ropy l e ne t e t r a me r . A n i on i c s u r f a c ta n t s w i t h phos -

pha t e e s t e rs a r e f i nd i ng more a nd m ore us e s i n i ndus t ry a nd a r e ob t a i ne d by t r e a t i ng

n o n - i o n i c s u r f a ct a n ts w i th p h o s p h o r o u s p e n t o x i d e .

4 . 4 . 2 C a t i o n i c s u r f a c t a n t s

C h e m i c a l l y t he y a r e j u s t opp os i te t o t he a n i on i c s u r f a c t a n t a nd he nc e a r e uns u it -

a b l e fo r u s e a s de t e rge n t s o r w e t t i ng a ge n t s . The hy droph ob i c pa r t o f t he m ol e c u l e

o f t h e c a ti o n i c s u r f a c ta n t is t h e o r g a n ic a m m o n i u m o r p y r i d i n i u m c o m p o u n d c o n -

t a i n in g o n e o r m o r e h y d r o p h o b i c r e s i d u e s a s s h o w n b e l o w :

@ . / " C H 2 - (C H 2 ),4 - C H 3

NClC e t y l py r i d i n i um c h l o r i de

C a t i on i c s u r f a c t a n t s a r e ra r e l y us e d i n p r e pa ra t i on un l e s s a pp l i e d a s a l ub r i c a n t



Scour ing 97

or ant i s ta t a t the end of the scour cyc le o n goo ds tha t a re to be d yed bu t not b leached.

A sm a l l qua n t i ty o f c a t ion ic su r f a c t a n t i s a l so r e c om m e nde d a s a n a id in we igh tr e duc t ion in ca us t i c t r e a tm e n t o f po lye s t e r . C a t ion ic su r f a c t a n t s a r e m a in ly u se d a s

so f t e ne rs , l e ve l l ing a ge n t s , r e ta r da n t s in dye ing , wa te r re pe l l e n t s , ba c te r i a g r owth

inhib i tor s and emuls i f ie r s .

4 . 4 . 3 N o n - i o n i c s u r f a e t a n t s

No n- ion ic s a r e s e c ond m a jo r su r f a c ta n t c l as s u se d in p r e pa r a t ion a nd a r e m a n u-

fac tured in d i f fe rent forms. No n- ion ic sur fac tants do not conta in an ionisable group

a nd ha ve no e l e c tr i c a l c ha r ge ( Ta b le 4 .2 ) . The m os t im po r t a n t non- ion ic de te r ge n t s

T A B L E 4 . 2

No n- ion ic S ur f a c t a n t s tha t B e a r a n E le c t r i c a l ly Ne u t r a l C ha r g e

E O - P O E t h e r s

E O - P O E s t e r s

Fa t ty es te r s

Am pho te r i c ( a t i soe le c tr i c po in t )

Th ioe the r sSorbi tan es te r s

S or b i t a n e s t e r -EO

Sorbi to l e s te r s

S or b i to l e s t e r - EO

EO f a t ty a c id

PO fa t ty ac idFa t ty a lka no l a m ide s

a r e those ob ta ine d b y c onde nsa t ion o f ethy le ne ox ide o r p r opy le ne ox ide . E thy le ne

oxide ca n be reac ted w i th fa t ty ac ids , a lcohols and a lkyl phenol , f a t ty am ide e tc . to

g ive po ly oxy e thy le n e c o m p oun d o f e the r, e s te r a nd a m ide know n a s e thy le ne ox -

ide c onde nsa t ion p r odu c t ( F ig . 4 - 7 ). The non- ion ic s a re r e nde r e d w a te r so lub le by

No n- ion ic de te r ge n t C he m ic a l s t ruc tu re

E t h o x y l a t e d p r i m a r y a l c o h o l

E t h o x y l a t e d n o n y l p h e n o l

E thoxy la t e d th io - e the r s

E tho xy la t e d f a t ty a c ids

E t h o x y l a t e d f a tt y a m i d e

R-O-(C2H40)nOH

C9Ul9~)O(C2H4O)nu

C Hg- S - C 2H4- ( C 2H40 ) nH

O

R-~-(CzH40) OHR - C O N - ( C 2 H 4 0 ) H

H

Figur e 4 - 7 . S om e typ ic a l e xa m ple s o f non- ion ic s .



98 Sc o u r i n g

t h e s o l v a t i o n o f o x y g e n i n t h e e t h e r a n d t h e s o l u b i l it y i s p r o p o r t i o n a l t o t h e n u m b e r

o f s u c h o x y g e n a t o m s i n th e m o l e c u l e . A p r i m a r y h y d r a t e is f o r m e d i n w h i c h f u r -t h e r w a t e r m o l e c u l e s p a r t ic i p a te , r e s u l t i n g i n t h e f o r m a t i o n o f v o l u m i n o u s h y d r a t e

s h e a t h w i t h 2 0 to 3 0 w a t e r m o l e c u l e s t o e a c h o x y g e n a t o m . S o m e t y p i c al e x a m p l e s

o f n o n - i o n i c su r f a c t a n t s a r e g i v e n i n F ig . 4 - 7 .

N o n - i o n i c s a r e c h a r a c te r i s e d b y i ts c l o u d p o i n t. I t i s t h e t e m p e r a t u r e a t w h i c h

1 . 0% s o l u t io n o f n o n - i o n i c s u r f a c ta n t s , b e c o m e c l o u d y o r i n s o lu b l e . T h e l a rg e r t h e

n u m b e r o f e t h y l e n e o x i d e m o l e c u l e s i n th e p r o d u c t, h i g h e r i s t h e c lo u d p o i n t . T h e

e x c e p t i o n t o t h i s r u l e i s a n o n - i o n i c t h a t i s c o - r e a c t e d o r c a p p e d , w i t h p r o p y l e n e

o x i d e . A n o t h e r m e t h o d o f o v e r c o m i n g t h e p r o b l e m o f c l o u d p o i n t is t o b l e n d t h e

n o n - i o n i c w i t h a n a n io n i c s u c h a s a s o ap , a s u l p h o n a t e o r a p h o s p h a t e . T h e c l o u d

p o i n t o f n o n - i o n i c s u r f a c t a n t s o lu t i o n c a n b e d e p r e s s e d b y t h e a d d i ti o n o f a n e l ec -

t r o l y t e l i k e c o m m o n sa l t , G l a u b e r ' s s a l t e t c .

N o n - i o n i c su r f a c t a n t s a re fr e e fr o m p r e c i p i t a t i o n a n d r e d e p o s i t i o n o n t o t h e f a b -

r i c a n d c a n b e s a f e l y u se d wh i c h a l so p e r m i t th e c a u s t i c to a c t a s a l i m e - so a p d e t e r -

g e n t . I ts a d v a n t a g e s a r e e x c e l l e n t c o m p a t i b i l i t y w i t h a l l c l a s se s o f su r f a c t a n ts , g o o d

w e t t e r s a n d r e w e t t e r s , g o o d e m u l s i fi e r s , e x c e ll e n t o il s o l u b il it y a n d g o o d c o m p o -n e n t s o f o i l e m u l s i f i e r.

4 .4 .4 A m p h o t e r i e s u r f a et a n t s

A m p h o t e r i c s u r f a c t a n t s m a y b e c a ti o n ic , a n i o n i c or n o n - i o n i c d e p e n d i n g u p o n

t h e p H o f t h e a q u e o u s s o l u t io n ( T a b l e 4 . 3 ). A t y p i c a l a m p h o t e r i c s u r f a c t a n t c a n b e

T A B L E 4 . 3 .

E f f e c t o f p H o n I o n ic N a t u re o f A m p h o t e r ic

S t r u c t u r e p H I o n i c c h a r g e(-) (+)C 1 R N H 2 C H 2 C H 2 C O O H A c i d i c C a t i o n ic

(+) (-)

R N H 2 C H 2 C H 2 C O 0 I s o el e ct ri c r a n g e N o n - i o n i c(-) (+)

R N H C H 2 C H 2 C O O N a A l k al in e A n i o n ic

r e p r e s e n t e d b y t h e f o l l o w i n g f o r m u l a "

/ C H 2 ~

N C H 2II

/ V ~ A A - C N - C H 2C H 2 O C H 2C O O - N a +I

C H 2 C O O -



Scour ing 99

Am ph o te r i c su r f a c t a n t s o f f e r a n e xc e l l e n t de g r e e o f lub r i c a t ion , c o r r os ion in -

h ib i to r , a nd we t t ing a c t ion a nd p r ov ide a p r o te c t ive c o l lo id f o r s i lk a nd wo o l p r o -c e s s in g . T h e m a j o r u s e s o f a m p h o t e r i c s a r e in t h e s c o u ri n g a n d d y e i n g o f p r o t e i n

f ib r e s t o p r e v e n t c h a f in g , c r a c k m a r k s a n d c r o w ' s f e et . A m p h o t e r i c s a r e c o m p a r a -

t i v e ly e x p e n s i v e a n d s o m e o f t h e m a re n o t h e a t s ta b le a n d h e n c e c a n n o t b e u s e d a t

e l e va te d t e m pe r a tu r e .

4 . 4. 5 B l e n d s o f su r f a c t a n t s

B le nde d su r f a c t a n t s a r e c om m only use d in p r e pa r a t ion a ux i l i a r i e s a s the y a r e

f o u n d t o b e m o r e e f f ic i e n t th a n t h e s i n g le c o m p o n e n t . W h e n n a t u r a l w a x e s , a n d

s iz e s a re to be r e m ov e d f r om c o t ton , a n ion ic s - o r non- ion ic s bu i l t w i th a n ion ic s -

a ppe a r to be the be t t e r c ho ic e . An ion ic s , whe the r su lpha te o r phospha te de r ive d ,

wh e n ne u t r a l i z e d wi th a m ine s o r a lka no la m ine s be c om e so lve n t a nd oi l so lub le a nd

m a y b e u s e d i n c o n j u n c t io n w i t h lo w - m o l e e t h o x y l a t e s. A b l e n d o f p r o p y l e n e o x -

i d e - c a p p e d n o n - i o n i c s o r t h io e t h e r e t h o x y l at e s , c o u p l e d w i t h l o w - m o l e p h o s p h a t e

e s t e r o f d inony l phe no l e tho xy la t e s tha t ha s be e n ne u t r a l i s e d wi th a lka no la m ine , i s

c o m m o n l y u s e d t o e m u l s i fy a h i g h b o i l in g m i n e r al s p ir it ty p e s o l v e n t. T h i s c o m b i -

n a t i o n p r o d u c t p r o v i d e s g o o d d e t e r g e n c y a n d s a t i s fa c t o ri ly a c c o m p l i s h e s t h e r e-m ova l o f process ing o i l s , g reases and s izes. A s imple b lend o f shor t -cha in e thoxyla tes

a n d l o n g - c h a i n e t h o x y l a t es o f s a m e h y d r o p h o b e t h a t p r o v i d e s a b a l a n c e d H L B c a n

som e t im e s be the be s t c ho ic e . On m a ny oc c a s ions , i t i s ne c e s sa r y to inc o r po r a t e a

s o l v e n t p r o c e s s in g a i d s a n d a c o m p l e x m i x t u r e o f e t h y l e n e o x i d e a n d f a tt y a c id

d e r i v a t i v e s p r o d u c e d w i t h i n o r g a n i c c o m p o u n d s t o p r o v i d e o p t i m u m p r o c e s s i n g

eff ic iency.

4 . 4 .6 S u r f a c t a n t a s w e t t i n g a g e n t

Ge n e r a l ly in t e r r a c ia l t e ns ion b e twe e n the t e x ti l e f ib r e a nd the l i quor i s h igh , a nd

he nc e w e t t ing o f the f ib r e su r f a c e doe s no t ta ke p l a c e qu ic k ly . T h i s i s pa r t i c u la r ly

t r ue in the c a se o f g r e y c o t ton f a b r i c a nd hydr ophob ic f ib r e s . One o f the m a in

f unc t ion o f the su r f a c t a n t s i s t o r e duc e the su r f a c e t e ns ion a nd the r e b y b r ing a bou t

w e t t ing o f the su r f a c e .

W a t e r h a s a n u n c o m m o n l y h i g h s u r fa c e te n s i o n o f 7 2 d y n e s / c m . T h e m o s t i m -

por t a n t f e a tu r e a bou t h igh su r f a c e t e ns ion o f wa te r is it s s tr uc tu re . A lone o xyg e n

a t o m i n th e w a t e r m o l e c u l e s c o n t a i n s a p a ir o f e l e ct ro n s , w h i c h i s b a l a n c e d b y ac o r r e spond ing ly l a r ge pos i t ive c ha r ge in the hydr oge n a tom s . Th i s s t r uc tu r e g ive s



100 Scour ing

w a t e r a g re a t d ip o l e m o m e n t , a n d a l s o t he m o l e c u l e s ' s t ic k ' t o on e a n o t h e r w h e n

w a te r i s i n i ts l i q u id p h as e . I t i s a m ix tu r e o f c lu s te r s o f t e t r ah y d r a l l y l i n k ed w a te rm o l e c u l e s a n d a si n g le m o l e c u l e , w i t h s i n g le m o l e c u l e o c c u p y i n g s p a c e s b e t w e e n

th e c lu s t e rs . T h e w a te r m o lecu l e s i n t h e c lu s te r s an d m o lecu l a r ag g r eg a t e s a r e h e ld

to g e th e r b y s t r o n g b o n d s . T h e e n e r g y o f a h y d r o g en b o n d i s ev en g r ea t e r th an t h a t

o f an y o th e r m o lecu l a r i n t e r ac t io n . A l l t h e s e f ac to rs e i t h e r a lo n e o r t o g e th e r m ak e

the w et t in g o f tex t i les d i f f icu lt .

I t i s p o s s ib l e t o b r in g d o w n th e s u r f ace t en s io n o f w a te r f r o m 72 d y n es / cm to 2 8

d y n es / cm b y d i s s o lv in g s o ap i n w a te r . Wh en a s u r f ac t an t ( s o ap ) i s d i s s o lv ed i n

w a te r t h e h y d r o ca r b o n ch a in (h y d r o p h o b ic p a r t t ai l, ==) t ri e s to g e t aw ay f r o m th e

CH3(CHz)~6COONa ~ CH3(CH2),6COO-+N a +. . . . . - . . . . . . . . . .

F ig u r e 4 - 8 . Su r f ace ac t i v i ty an d o r i en t a t io n o f s o ap m o lecu l e s .

w a te r m e d iu m d u e t o it s h y d r o p h o b ic i t y (F ig . 4 - 8 ) an d co n cen t r a t e a t t h e s u r face .

T h e h y d r o p h i l i c g r o u p in g ( ca r b o x y l h ead , O) j u s t d ip i n t h e w a te r a t t h e s u r f ace an d

th e s o d iu m ca t i o n i s in t h e v i c in i t y o f n eg a t i v e ly ch a r g e d ca r b o x y l h ead . T h u s t h i sco m p o u n d , s o d iu m s t ea r a te ( s o ap ) , d is t o r t t h e s t ru c tu r e o f w a t e r an d d ec r eas e t h e

f r ee en e r g y o f th e s y s t em .

H o w e v e r , t h e re i s a n o th e r m e a n s o f m i n i m i s i n g f re e e n e r g y o f th e s e s y s t e m s .

T h e d i s to r t i o n o f t h e s o lv en t s t r u c tu r e can a l s o tak e p l ace b y ag g r eg a t i o n o f th e

s u r f ac t an t m o lecu l e s i n to c lu s t e r s (m ice l l e s ) w i th t h e i r h y d r o p h o b ic g r o u p in g s d i -

r ec t ed t o w ar d t h e i n t e r i o r o f t h e c lu s t e r an d th e i r h y d r o p h i l ic g r o u p s d i r ec t ed t o -

w ar d s t h e s o lv en t. Mice l l i s a t io n i s t h e r e fo r e a m ech a n i s m a l t e rn a t i v e t o ad s o r p ti o n

at the in te r faces fo r r em ovin g lyopho bic g rou ps f rom the con tac t wi th water , thereby

r ed u c in g t h e f ree en e r g y o f t h e s y s t em .



Scour ing 101

T h e w e t t i n g a g e n t n o t o n l y f a c il i ta t e s th e w e t t i n g o f t h e f ib r e b y w a t e r b u t a l s o

r e s u l ts i n t h e d i s p l a c e m e n t o f ai r fr o m t h e m i c r o p o r e s o f c o t to n b y t h e w a t e r. T h u st h e we t t i n g o f a su r f a c e i n v o l v e s t h e r e d u c t i o n o f in t e r f a c i a l t e n s i o n , so t h a t l iq u i d

s p r e a d s a s a c o n t i n u o u s f i lm i n s t e a d o f r e m a i n i n g a s d ro p s ( Fi g . 4 -9 ) . W h e n t h e

F i g u r e 4 - 9 . A n g l e o f c o n t a c t, 0 .

i n t e r f a c i a l t e n s i o n i s l a r g e , th e a n g l e o f c o n t a c t i s a l so l ar g e . S u r f a c t a n t s c a n r e d u c e

t h e a n g l e o f c o n t a c t , s i n c e t h e y f a c i l it a t e we t t i n g ( sp r e a d i n g ) o f t h e l i q u i d o n t h e

su r f a c e . T h e r e l a t i o n sh i p b e t w e e n t h e v a r i o u s f o r c e s c a n b e wr i t t e n a s 9

c o s O = -T,

F o r p e r f e c t w e t t i n g o f t h e f ib r e , 0 m u s t b e z e r o , so th a t ,

Ts - T~s - Co s O ~ - 1

or, T s - T l s = T I

T h i s m e a n s t h a t i f 0 i s l e s s t h a n 90 ~ t h e o il w i l l t e n d to sp r e a d o v e r t h e f i b r e a n d

a d h e r e t o i t. B u t i f 0 i s g r e a t e r t h a n 90 ~ t h e o i l w i ll t e n d t o f o r m g l o b u l e s w h i c h a r e

e a s i l y d e t a t c h e d f r o m t h e f i b r e . T h e e f f e c t o f a d d i n g su r f a c t a n t t o wa t e r i s th a t th e

su r f a c t a n t m o l e c u l e s w i l l c o n g r e g a t e a t t h e o i l / fi b r e (T s ) a n d e v e n m o r e a t o i l/

w a t e r ( T ~ s ) i n t e r f a c e s , t h u s r e d u c i n g t h e v a l u e s o f C o s 0 .

4 . 4. 7 S u r f a c t a n t a s d e t e r g e n t ( s c o u r i n g a g e n t )

T h e f u n c t i o n o f t h e d e t e r g e n t is t o r e m o v e t h e d i r t a n d d u s t p a r t i c l e s a n d o t h e r

c o n s t i t u e n t s o f t h e s i z e su c h a s c h i n a c l a y f r o m t h e c o t t o n f a b r i c . T h e d e t e r g e n t

k e e p s t h e s o i ls i n d i s p e r s e d o r s u s p e n d e d f o r m i n s c o u r i n g s o l u t i o n a n d p r e v e n t s

r e d e p o s i t i o n o n t h e f a b ri c . F ig . 4 - 1 0 i l l u s t r a t e s t h e s e q u e n c e o f e v e n t s o f so il re -

m o v a l . A d v e n t i t i o u s d i r t a d h e r e t o t h e f a b r i c b e c a u se t h e o i l a c t s a s a n a d h e s i v e

t o w a r d s i t . T h e f a b r i c / s o i l / w a t e r i n t e r f a c e s n o t s o l u b l e i n w a t e r i s s h o w n i n



102 Scouring

Fig . 4-10 (A) . W hen detergent i s added [Fig . 4-10 (B)] , the so il hyd roph obe e i ther

d isso lves in to the so i l or or ien t a long the f ibre surface . The larges t concent ra t ion ofdeterge nt i s present a long the edge o f the so il . Beca use of the hydrophi le , the edges

tend to associa te wi th water and thus the removal of so i l f rom the fabr ic s tar t s .

Ult imately, the oi l disperses as droplets [Fig. 4-10 (C)] and the dir t is held in sus-

pens ion wi th in the drople t s [8] . The suspended so i l par t ic les wi th i t s sheath of

/ ........ , _ - ~ - - ~

- - - t~ ~ i ... :-~61i~i~II --i~i i-ii i'-'-'~--

Y~. Fab rl c-mo ll interface.

[ . . . . ii i ]B. Ori entat ion begins.

-

C . l ~ d o e e f f e c t

. . . . DR OP AET

D. Remora I oE so l I.

Figure 4-10. Schem et ic d iagra m of events caus ing detergenc y [7].

or ien ted soap mo lecules assum es a net negat ive charge s imi lar to the g lobular

micel le of soap . Cot ton f ibres a l so take up a negat ive charge when immersed in

water . T he e lec t ros ta t ic repuls ions b etw een the par t ic les and the f ibre p lay a majo r

ro l e i n p reven t ing redepos i ti on . T he add i t ion o f ca rboxym ethy l ce l lu lose (CM C)

and/or poly viny l pyrol ido ne (PVP) (Fig . 4-11) can act as an t i- redepos i t ion agen ts .

C H 2 O C H 2 C OO N a H O H H 2 C - - C H 2

~ H H ~ H O ~ X ~ j # ~ ~ _ H2C C = O]H "~ O \ N /

H OH CH2OCH2COON a n - CH - CH 2 - nC M C P V P

Figure 4 -11 . Chem ica l s t ruc tu re o f CM C and PVP.



Scou r ing 10 3

C M C i s u se d p r im a r i ly in su r f a c t a n t s a nd PVP i s u se d a s ba th a dd i t ive . Fu r the r ,

C M C a l so f o r m s a p ro te c t ive c o l lo id w i th the so il a nd thus p r e ve n t s so i l r e de pos i t ion

on the c lo th . The e m uls ion o f o il a nd d i rt shou ld be s t ab le , o the r w ise the r e w i l l be

r e de po s i t ion . Or d ina r y soa p a nd de te r ge n t is a good e m u ls i f y ing a ge n t .

Th e m os t im por t a n t c ons ide r a t ion in s c our ing i s t he c r it i ca l m ic e l l e c on c e n t r a -

t ion ( C M C ) o f the su r fa c t a n t . A r e se r vo i r i s e s t a b l i she d a t t he C M C a nd se ve r a l

f a c to r s be c om e e v ide n t ( F ig . 4 - 12) . The de te r ge n c y is a t i ts m a x im um wh i l e the

>.

. , .4

>- . 4

u

CRC

- ~ ' ~ - ~ D e c e r ; e n c y

AN'~i.., ~ , a c e Tension (S t )

\ ~ i . . . . . . . . . . . . . . . . . . . I n t e r . ~ a c i a l T e n s i o n ( I t )

0,i 0.2 0.3 0.4 0.5Soap Concentration (OW~))

Figur e 4 - 12 . R e la t ions h ip be twe e n de te r ge nc y , su r f a c e

te ns ion , i n t e r f a c ia l t e ns ion a nd C M C [9] .

su r f a c e t e ns ion a nd in t e r f a c ia l t e ns ion a re a t t he i r m in im u m . The C M C i s d i f f e r e n t

f o r d i ff e r e n t m o le c u la r s t r uc tu r e o f su r f a c ta n t s , a nd i t va r i e s w i th t e m pe r a tu r e , a g -

g l o m e r a t i o n n u m b e r a n d a v e r a g e n u m b e r o f m o l e c u l e s p e r m i c e l le .

4 . 4 . 8 E m u l s i o n s c o u r i n g

The kn i t t i ng ya r n in c o t ton we f t kn i t t e d f a b r i c s c on ta ins lub r i c a n t s wh ic h r e -

p la c e the s i ze on wov e n f a b r ic s . L ubr i c a n t s a re w ide ly use d in w or s t e d a nd w oo l l e n

se c to r s o f t he woo l indus t r y , p r im a r i ly to a id p r oc e ss e s suc h a s c a r d ing , c om bing

a nd sp inn ing . A t the fina l s t a ge s o f m a nu f a c tu r ing o f syn the t i c f ib re s , the y a r e

sub je c te d to o i l ing to im pr o ve the i r phy s ic a l a nd m e c h a n ic a l p r op e r t i e s a nd to fin -

ishing w ith an ti-s ta t ic age nts to reduce their abil i ty to be e lectr if ied [ 10,11 ] . Stabil isedb u l k e d - p o l y e s t e r y a m s f o r w e f t k n i t t in g a re h e a v i l y o i le d .



10 4 S c our i ng

The t e rm ' ya m l ub r i c a n t s ' ( o r c on i ng o i l) is de f i ne d a s al l l ub r i c a n t s a pp l i e d by

t e x t i le m i l l o r p roc e s s o r s s ubs e qu e n t t o a pp l i c a t i on o f s p in f i n is h . I nc r e a s i ng l y s o -ph i s t i c a t e d s p i n f in i s he s a r e u s e d a nd l ong g roup o f c om pou nds a r e kno w n t o se rve

as f ibre lubr icant s , m inera l o i l s be in g used s ince long. S t ra ight cha in es te rs such as

m ethy l , e thyl or buty l of fa t ty ac ids w i th fu nc t iona l grou ps C 6 to C~8 a re the l a rg es t

g rou ps ha v i ng e xc e l l e n t l ub r ic i t y . Po l yg l yc o l s o r t he i r f a tt y a c i d e s te r s a nd f a tt y

g l yc e r i de s , m ore c om pl e x c he m i c a l s s uc h a s e s te r s o f d iba s ic a c ids , pe n t a c ry th r i t o l,

ne ope n t y l e ne g l yc o l , a nd po l yc e ro l s a s w e l l a s a ry l , a l ky l , a l ky l a ry l phos pha t e s ,

s i l icones , s i li ca te es te rs , fluroes te rs and polyp hen yl e the rs have been used for grea te r

s t ab i l it y . L ub r i c a n t s ha ve b e e n m od i f i e d b y e s t e r in t e r c ha nge , e t hoy l a t ion o r a c e ty -

l a t ion i n o rde r t o i n f l ue nc e t he de g re e o f l ub r i c i ty a nd o t he r p rope r t i e s . The m a i n

l ub r i c a n t s , how e ve r , u s e d a r e s a pon i f i a b l e , w a t e r e mu l s i f ia b l e ( e s t e r ba s e d) , w a t e r

d i s pe r s i b l e a nd w a t e r s o l ub l e ( su r f a c t a n t ba s e d). O u t o f t he s e e st e r ba s e d a nd w a t e r

s o l u b le t y p e s a r e m o r e p o p u l a r b e c a u s e o f t h e ir t e ch n i c a l p e r f o r m a n c e a n d e a s e o f

r e m ova l . Ta b l e 4 .8 s how s a r a nge o f t yp i c a l a pp l i c a t i on l e ve l s u s e d fo r t he m a i n

T A B L E 4 . 8 .

M a i n T y p e s o f L u b r i c a n t s U s e d o n t h e W o o l l e n S y s t e m [ 12 ]

Y a rn e nd us e L ubr i c a n t A pp l y ( o . w . f. )

Fa br i c s S a pon i f i a b l e

Em ul s i f ia b l e 5 - 7 %

H o s i e ry E m u l s if ia b le 4 - 1 1 %

C a rpe t s Emul s i f i a b l e

D i s pe r s i b l e

W a t e r s o l ub le

1 - 5 %

t ype s o f l ub r i c a n t s on the w oo l l e n s ys t e m. M os t o i ls ha ve l ow e r r e f l e c t i ve i nd i c e s

t ha n d ra w n p o l ye s t e r f ib r e s , s o tha t t he p r e s e nc e o f o il on the s u r f a c e o f the f i b r e

r e duc e s t he s c a t t e r i ng o f i nc i de n t l igh t ; i mpa i r l e ve l dye i ng p rope r t i e s a n d t he f a s t-

ne s s t o w a s h i ng a nd rubb i ng ; a nd mo d i fy t he s t ruc t u r e o f po l ye s t e r f i b r e s on s t o r-

a ge a nd t he rma l t r e a t me n t . A p rop e r s e l e c t ion o f l ub r i c a n t s is ne c e s s a ry s o t ha t

s c o u r i n g m u s t b e t h o ro u g h .

N on- s c oura b l e o i l s a r e d i f f i c u l t t o r e move f rom c o t t on g i v i ng r i s e t o un l e ve l

dye i ngs [ 13 ]. The o i l , g r e a s e a nd ta r st a in s a r e ge ne ra l l y r e m ove d by s po t t i ng on



Scour ing 105

s ta ine d po r t ion wi th s t a in r e m ove r c om pr i s ing e m uls i f i e d so lve n t s in the l i qu id

f o r m . The s t a ins a r e spo t t e d w i th s t ain re m ove r a nd r ubbe d a nd l e ft f o r sho r t t im ea nd the n wa she d . The p r oc e ss m a y be r e pe a te d to r e m o ve s t a ins c om ple te ly . The

t r e a t e d a r e a s howe ve r shou ld no t d r y be f o r e the y a r e wa she d a s o the r wise r ing

m a r ks a r e l i ke ly to be f o r m e d . Em uls i f i e d so lve n t s ( Ta b le 4 .9 ) a re u se d in the

T A B L E 4 . 9 .

T y p e o f E m u l s i f ie d S o l v e n ts

Type Sur fac tants ( emuls i f ie r ) Solvents

Anion ic s S u lpha te d o i l, C a r bon t e t ra c h lo r ide ,a lkyl a ry l su lphon a tes , and t r ich loroe thy lene .

E thy le ne ox ide c onde nsa te Pe r c h lo r oe thy le ne ,

wi th a lky l phe no l s , f a tty i sop r opy la l c oho l ,

a l c oho l s a nd f a t ty a c ids , oxyc y c lohe xa ne ,

c h lo r obe nz e ne ,

be nz y l a l c oho l.

N o n - i o n i c s

f o r m u la t ion o f s t a in r e m ove r s . T he y a r e u sua l ly o r ga n ic so lve n t s c on ta in ing e m ul -

s i fi e r d i s so lve d in the m a nd he nc e be c o m e se l f -e m uls i f i a b le . The so lve n t m us t be

c a pa b le o f d i s so lv ing the hyd r oc a r bon im pu r i ty a nd the de te rge n t m us t be c a pa b le

o f e m uls i f y ing bo th the hydr oc a r bon a nd the so lve n t . S o lve n t s b l e nde d wi th su r -

f a c ta n t s a r e c l a im e d to ha ve supe r io r e nv i r onm e n ta l be ha v iou r a long w i th e xc e l le n t

g r e a se r e m ova l [ 14 ].

O the r a l t e r na t ive m e tho ds a r e tha t t he pow e r f u l s t a in r e m ov e r s m a y be a pp l i e d

f r om the ba th a long wi th we t t ing a ge n t s c um de te r ge n t s a t h igh t e m pe r a tu r e a ndso lve n t s c our. One suc h f o r m ula t ion w h ic h ha s be e n wide ly use d f o r po lye s t e r /

c o t ton b le nde d f a b ri c s f o r r e m o v ing u nsa pon i f ia b le wa xe s f r om c o t ton po r t ion a pa r t

f r om lub r i c a n t s a nd c o nn ing o i l s f r om the ya m i s g ive n in Ta b le 4 .10. The l e ft ove r

T A B L E 4 . 1 0 .

E m u l s i o n S c o u r i n g R e c ip e

I ngr e d ie n t s P r opor t ion by we ig h t

Esse n t i a l O i l

Pe r c h lo r oe thy le neEm uls i f i e r

(e .g . nonyl phenol , HLB = 13-15)

40 - 50 pa r t s

20 - 10 pa r t s

40 pa r ts

Tota l 100 par ts



106 Scour ing

s o l u ti o n a s w e l l as th e w as h w a t e r a r e r emo v ed . Ru s t s t a in s a re b es t r emo v ed b y

oxal ic ac id up to 10 g/1 a t abou t 60-70~ fo l low ed by wash ing .T h e m ech an i s m b y w h i ch em u l s i o n s co u r i n g o ccu r s is a tt r ib u t ed to t h e h y d ro -

p h o b i c p o r t i o n o f t h e mi ce l le b e i n g s a t u ra t ed w i t h t h e s o lv en t. T h e m i ce l le , w h en

loade d w i th so lven t , i s m ore e f fec t ive in so lub i li s ing o i ly impu r i t ies f rom the fabr ic

t h an i s t h e d e t e rg en t a l on e , p ro v i d ed b o t h s o l v en t an d e mu l s i fi e r a re p ro p e r l y s e -

l ec ted and used . The c r i ti ca l fea tu re o f such a so lven t i s i ts KB V alue , w hich i s a

m eas ure o f i ts so lven cy fo r a par t i cu lar o i ly so i l.

4 .5 S o l v e n t S c o u r i n g

So lven t scour ing appears to be a l t e rna t ive to aqueou s scour ing and par t i cu lar ly

s u i tab l e fo r p o l y es t e r an d w o o l l en g o o d s . T h i s p ro ces s n o t o n ly p e rmi t s s co u r i n g ,

bu t a l so s imul taneous scour ing and des iz ing o r even par t i a l b leach ing in one s t ep

[ 15 ,16] . So lv en t scour ing i s a l so usefu l fo r the remo val o f lubr ica t ing o i l s f rom

k n i t t ed p o l y es t e r, o l i g o m er f ro m p o l y es t e r and b u lk i n g o f k n i t t ed g o od s . W o o l

fe l ts l es s in so lven t med ia and i s par t i cu lar ly usefu l in wool m i l l ing and app l ica t ion

of sh r ink- res i s t res ins to woo l [ 17]. So lven t p rocess ing has been es tab l i shed due to

r ed u ced w a t e r p o l l u t i o n , r ed u ced en e rg y co s t an d co n s u mp t i o n ap a r t f ro m e f f ec -t iv e r em o v a l o f imp u r i ti e s . So l v en t p r ep a ra t io n g i v es ex ce ll en t r e s u l ts i n t e rms o f

u n i fo rm i t y , r ep ro d u c i b i l i t y an d h i g h ab s o rb an cy [ 1 8] .

Bas i ca l l y s o l v en t s co u r i n g i s a r e f i n emen t o f d ry -c l ean i n g an d i s ca r r i ed o u t

e i ther ba tc hw ise o r con t inu ous ly (C hapter 5 ). So lven t s in tended fo r use in t ex t i le

p ro ces s i n g s h o u l d i d ea l ly b e i n ex p en s i v e , r ead i l y o b t a i n ab l e , n o n - t o x ic , n o n - f l am-

ma b l e , s t ab l e to r ep ea t ed r eco v e ry , i n e r t t o t ex t il e s an d n o n -co r ro s i v e . T h e m o s t

s u i t ab l e s o l v en t s fo r t ex t i l e p ro ces s i n g a r e t h e ch l o r i n a t ed h y d ro ca rb o n s , e .g .

tet rachloroe thylene (perch loroethylene) , t r ichloroethylene and 1,1,1- tr ichloroethane.

P e rch l o ro e t h y l en e i s w i d e l y u s ed i n d ru m m ach i n e [ 1 9] . T r i ch l o ro e t h y l en e i s b e s t

av o i d ed b ecau s e o f it s s tr i p p in g ac t io n o f d y ed p o l y es t e r ma t e r i a l s i f t h e t emp e ra -

tu re shou ld r i se above 30~ One im por tan t fac to r fo r so lven t p roc ess ing is the

s tab i l i ty o f so lven t s to recove ry by d i s t il l a t ion o r by adsorp t ion p rocess . The re -

cov ery o f s tab i l i se r in the so lven t s is a l so equa l ly imp or tan t . The s t ab i li se rs recom -

m end ed fo r d i f fe ren t so lven t s a re shown in Tab le 4 .11 . In cer ta in p rocesses 'boos te r

so lv en t s ' a re added to perch loroe thy lene . The y are gene ra l ly d ipo lar apro t i r so l -v en t s [ 2 7 .2 8 ] . So i l r em o v a l i n ch l o r i n a ted h y d ro ca rb o n s can b e i mp ro v ed b y t h e

ad d i t i o n o f s o l v en t d e te rg en t s, e .g . m o n o e t h an o l am i n e , a l k y l b en zen e s u l p h o n a t e ,



Scour ing 107

TABLE 4 .1 1

Solven ts and Stab i l i se r s fo r Tex t i le S cour ingSolv ent Stabil isers Ref .

Tr ich loroe thy lene Subst i tu ted d iamines 20

or

Perch loroe thy lene Cro tona ldehydedia lky l

hydrazones. 21

1, 1, 1 - t r ich lo r o e th an e Mix tu r e s o f ace to n i t r i l e

and n i t romethane 22or

Dim e th o x y e th an e an d

1, 4 - diox an. 23

Helog ena ted hydro carbon s Tr ie thy leor thoformate , 24

(general) Pho spho ric acid , 25

Benzotr iazoic . 26

a lky l po ly (g lyco l e ther ) and a lky l pyr id ine ch lor ide [29] . Such products a re usu-a l ly mix tures , e .g . dodecy lbenzene su lphonate (13%) , nonyl phenol a long wi th 5

e thy lene ox ide un i t s (5%) , i sopropyla lcoh ol (5%) , w ater (7%) and ch lor ina ted hy-

drocarbon (70%) . Ch lor ina ted hydro carbons con ta in ing such produc ts a re capab le

o f d i s so lv in g w a te r an d h en ce en h an ces d e te r g en cy .

The m ain d i f f icu l t ies o f so lven t scour ing a re the need fo r sys tem s to recover the

so lven t f rom fabr ics a f te r p rocess ing . Apar t f rom th is , so lven t can remo ve b inders

f rom bow l f i l l ings and ad hes ives f rom lamin a ted bowl cov ers and rap id ly a t tacks~

co n v en t io n a l r u b b e r co v e r in g s wi th ex p en s iv e e f f ec t . A t h ig h t em p er a tu r e s ad -

sorp t ion o f so lven t in to the f ib re web increases and the degreas ing ac t ion in subse-

quen t s team ing opera t ion can have em barass ing s ide e f fects . How ever , the g row-

in g p r o b lem s a sso c ia t ed wi th th e in c rea s in g d em an d f o r raw wa te r i n so m e co u n -

t r ies and d isposa l o f e f f luen t in genera l have g iven an imp etus to the so lven t scour -

ing sys tem.

4 .6 S c o u r i n g o f R a w W o o l

Raw wool i s d i f f icu l t to sp in because o f the na tu ra l g rease /wax (yo lk) , la rgepersp irat ion sal ts terme d suint , acquired im puri t ies l ike vegetab le matters, d ir t , pro-

t e in aceo u s co n tam in an t l ay e r s ( P CL) an d w o o l b u r rs w h ich co n ta in h em i - ce llu lo se



108 Scour ing

a nd l ign i n . F i ne r va r i e ti e s o f w o o l m a y c on t a i n f a t s a nd s u in t a s m uc h a s 50 % o f

t he w e i gh t o f r a w w oo l . The op t i ma l r e s i dua l w a x c on t e n t a ft e r s c our i ng s ho u l d beo f the o rde r o f 0 .5 t o 0 . 7 5% on l y be c a u s e a m oun t s i n e xc e s s o f t h is a r e l i a b le t o

c a us e t r oub l e i n c a rd i ng , do f f i ng a nd in s ubs e q ue n t dy e i ng p roc e s s e s . O n t he c on-

t r a ry , too l o w a w a x c o n t e n t i mp a i r s t he ha nd l e o f w oo l a s w e l l a s s p i nn i ng p rope r -

t ie s . To a c h i e ve s a t is f a c t o ry r e s i dua l g r e a s e c on t e n t on w oo l va r ious s c o ur i ng p ro -

c e dure s ha ve be e n us e d [ 30 ] .

4 . 6 . 1 E m u l s i o n s c o u r i n g

S c ou r i ng o f r a w w oo l i s c a r r ie d o u t i n t a nks f il le d w i t h de t e rge n t s o r o l e a te s oa p

( 2 -4% ) a nd s od i um c a rbona t e ( 2% ) a t 50 -55~ fo r 10 t o 15 r a i n . The pH o f t he

l i quor i s a bou t 10. I n p r a c t i c e t he r a w w oo l i s p rope l l e d g e n t l y th rou gh t he s c our -

i n g ta n k , t h e n s q u e e z e d b e t w e e n r o l le r s a n d t h en p a s s e d t h r o u g h a n o t h e r o r m o r e

t a nks i n t h i s w a y , un t i l e ve n t ua l l y i t i s r i n s e d i n c l e a n w a t e r. S uc h a m u l t i - s t a ge

s c o u r i n g e n v i r o n m e n t i s n e e d e d t o r e m o v e d i rt f ro m t h e w o o l .

The l e ve l s o f w o o l w a x a nd d i r t (a s h ) r e m a i n i ng a f te r c onve n t i ona l s c our i ng a r e

c on s i de ra b l y h i gh e r on t he t op t ha n ba s e (Ta b l e 4 .12 ) . The ha rd to r e m ove w oo l

w a x i s p r i nc i pa l l y ox i d i s e d w oo l w hos e e mul s i on s t a b i l i t y i s c ons i de ra b l y h i ghe r

T A B L E 4 . 1 2 .

L e v e l s o f R e s i d u a l C o n t a m i n a n t s o n P o r ti o n o f a W o o l F i b r e

P o r t i o n o f f ib r e W o o l w a x A s h

B a s e 0 . 46 0 . 42

Top 1 .18 4 .73

a nd i n mul t i s t a ge s c our i ng s ys t e m more e f f e c t i ve c on t a c t t i me i s a va i l a b l e fo r

s o l ub i l i s a ti on r a t he r t ha n ro l l i ng -up m e c ha n i s m [ 31 , 32 ] . Thus , i n t he fi na l s t a ge o f

s c o u r i n g i n p r e s e n c e o f d e te r g e n t , th e h a r d t o r e m o v e w o o l w a x i s s o lu b i l is e d b y

t he de t e rge n t t o fo rm a fa i rl y d i s pe r s e d m i c e l le s , w h e re a s t he s t rong l y a dhe r i ng d i r t

( i no rga n i c o r o rga n i c ) i s d i s p l a c e d b y t he a ds o rp t i on on non- i on i c de t e rge n t a t t he

f ibre / so lu t ion in te r face [33] . In the sur fac tant so lu t ion the re a re four s t ages in the

r e m o v a l m e c h a n i s m [ 3 4 ] :

i )

ii)iii)

i v )

a n in i ti a l s w e l l i ng o f t he p ro t e i na c e ou s c on t a m i na n t s ;

f o rma t i on o f g r e a s e g l obu l e s w i t h i n o r on , t he s w o l l e n PC L ;r e m o v a l o f t h e s w o l le n P C L w i t h a tt a c h e d g l o b u l es ; a n d

b r e a k i n g u p o f th e s w o l l e n P C L / g r e a s e c o m p l e x i n t o s p h e r ic a l o r i r re g u -

la r ly shaped par t i c les in so lu t ion .



Sc o u r i n g 1 09

4 . 6 . 2 S u i n t s c o u r i n g

I n t h i s p r o c e s s t h e d u s t e d r a w w o o l i s s t e e p e d i n wa t e r a t 16~ a n d t h e n th el i q u o r is w i t h d r a w n a n d c l a ri f ie d b y s e d i m e n t a t io n o r c e n t ri f u g i n g [ 3 5] . T h e p H o f

t h e su i n t l i q u o r i s b e t w e e n 5 .5 to 8 .8 . F o r r e m o v a l o f w a x t h e su i n t l i q u o r sh o u l d

b e h e a t e d a t 6 0~ w h e n w a x i s e m u l s i f ie d . T h e m a t e r ia l is i n t h e n r i n s e d , w a s h e d

w i t h s o a p a n d f i n a ll y ri n s e d i n th e s u b s e q u e n t b o w l .

4 . 6 . 3 S o l v e n t e x t r a c t i o n s c o u r i n g

A b o u t 9 0 % o f t h e w o o l w a x c a n b e r e m o v e d b y th is s y s te m . T h e r e c o m m e n d e d

s o l v e n t s a r e b e n z e n e , c a r b o n t e t r a c h l o r i d e , s o l v e n t n a p t h a , w h i t e sp i ri t ,

t r i c h l o r o e t h a n e e tc . I n o n e m e t h o d so l v e n t is a p p l i e d u n d e r h i g h p r e s su r e j e t o n th e

m a t e r i a l p l a c e d o n a p e r m e a b l e c o n v e y e r a n d d i s l o d g e s m u c h o f t h e d ir t a n d s u i n t

a p a r t f r o m r e m o v a l o f w a x f r o m t h e fi b re [ 3 6] . T h e s o l v e n t c o n t e n t o n t h e tr e a t e d

w o o l i s r e d u c e d t o a b o u t 4 5 % b y p a s s i n g t h r o u g h t h e r o l le r s a n d i s fu r t h e r r e d u c e d

t o a b o u t 1 0 % b y c e n t r if u g i n g . F i n a ll y , th e re s i d u a l s o l v e n t is r e m o v e d f r o m t h e

f i b r e b y b l o wi n g h o t a i r [ 3 7 ] .

4 . 6 . 4 R e f r i g e r a t i o n p r o c e s s

I n t h i s m e t h o d r a w w o o l i s f i r s t e x p o s e d t o l o w t e m p e r a t u r e e n v i r o n m e n t o fa b o u t - 3 0 ~ w h i c h f re e z es th e w a x a n d v e g e t a b le m a t t e r a n d t h us b e c o m e s h a rd

a n d b r it t le . I n t h e s e c o n d s t a g e th e se i m p u r i t i e s a re r e m o v e d f r o m t h e f ib r e b y

s o m e m e c h a n i c a l m e a n s [ 38 ].

4 .7 S c o u r i n g o f W o o l Y a r n a n d F a b r i c

T h e s c o u r i n g o f lo o s e w o o l is a c o m m o n p r a c t ic e , a l t h o u g h f u r t h e r s c o u r i n g o f

w o o l y a r n o r p i e c e i s o f te n c a r r i e d o u t to r e m o v e t h e a d d e d i m p u r i t ie s i. e. c o m b i n g

a n d s p i n n i n g o i l. H o w e v e r , b e f o r e s c o u r i n g t re a t m e n t s o f w o o l y a r n s a n d f a b ri c s,

p a r t i c u l a r l y a ll w o r s t e d s a n d w o o l / c o t t o n u n i o n a r e g iv e n o t h e r p r e - t r e a t m e n t p r o -

c e s se s l i k e c r a b b i n g a n d p o t t i n g .

4 .7 .1 S e t t i n g a n d s c o u r i n g o f w o o l y a r n

C e r t a i n y a r n s su c h a s t h o se f r o m c r o s s - b r e d w o o l s a r e we t s e t b e f o r e s c o u r i n g t o

p r e v e n t c o c k l i n g o c c u r i n g i n t h e p i e c e s . Se t t i n g o f y a r n i s c a r r i e d o u t b y s t r e t c h i n g

t h e h a n k s i n a su it a b l e f r a m e a n d t h e s tr e t c h e d h a n k s a r e i m m e r se d i n b o i l i n g w a t e r

f o r 3 0 m i n . T h e h a n k s a r e a l l o w e d t o c o o l u n d e r te n s i o n b e fo r e r e m o v i n g f r o m t h e

f r a m e .W o o l l e n y a r n s a r e n o r m a l l y s p u n w i t h a s a p o n i f ia b l e o i l, s u c h a s o le i n e b a s e d



110 S c our i ng

l u b r i c a n ts ( 7 0 % F F A / 3 0 % m i n e r a l o il ). S c o u r i n g c a n b e c a r ri e d o u t b y s a p o n i fi c a -

t io n s y s t e m u s i n g s o d a - a s h o n l y a n d f o r m i n g th e n e c e s s a r y s o a p b y r e a c t i o n w i t ht he o l e i c a c i d c on t e n t o f t he l ub r i c a n t . S oa p w i l l e xe r t a s t r ong e m ul s i fy i ng a c t i on

t o r e m o v e g r e a s e a n d d i r t f r o m w o o l y a r n . W o r s t e d y a r n s ar e g e n e r a l l y s p u n w i t h

up t o 3% o f e m ul s i f i a b l e o i l ( b l e nds o f m i ne ra l o i l a nd e m ul s i f i e r s ). Th i s is r e -

m o v e d b y s o a p a d d e d t o t h e s c o u r i n g b a t h t o g e t h e r w i t h a l k al i as a s o a p b u i l d e r o r

by a l ka l i ne s o l u t i ons o f s yn t he t i c de t e rge n t s . S u r f a c t a n t type s o f l ub r i c a n t s a r e

m a i n l y u s e d o n w o r s t e d a n d s e m i w o r s t e d s y s t e m s , a n d t h e l o w l e v e ls a p p l i e d a re

o f t e n r e m o v e d i n t h e d y e b a th . P o l y g l y c o l ty p e o f l u b r ic a n t s u se d f o r c a r p e t y a m

s p i n n i n g c a n b e r e a d i l y r e m o v e d u s i n g n o n - i o n i c d e t e r g e n t s in n e u t ra l c o n d i t i o n s .

4 . 7 .2 C r a b b i n g ( s e t ti n g ) o f w o o l l e n f a b r i c s

C r a b b i n g i s m e r e l y a r e l a x a t i o n p r o c e s s c o n d u c t e d u n d e r c o n t r o l l e d c o n d i t i o n s

b e f o r e s c o u r i n g to p r e v e n t d i s t o r ti o n d u r in g s u b s e q u e n t p r o c e s s i n g . R e l a x a t i o n

r e m o v e s t h e l a t e n t s tr a in i n t r o d u c e d i n t o th e y a r n b e fo r e b e i n g w o v e n . I n th e b a t c h

p r o c e s s t h e c l o t h is p a s s e d o p e n w i d t h u n d e r g u i d e r o ll e r s th r o u g h b o i l i n g w a t e r in

t he f i r st t r ough a nd i s t he n t i gh t l y w o un d o n t he low e r ro l le r o f t he t w o l a rge ro l l e r s

i n s u c h a w a y t h a t h a l f o f th e r o t a t i n g r o l l e r o f c l o th i s i m m e r s e d i n th e h o t w a t e r.T h i s t r e a t m e n t t a k e s a b o u t 5 m i n u t e s . T h e p r o c e s s i s r e p e a t e d b y p a s s i n g t h e c l o th

t o the s e c on d un i t . I n t h i s w a y t he ou t e r l a ye r o f t he c l o t h i n t he f i rs t t r e a t m e n t

b e c o m e s t h e i n n e r l a y e r d u r i n g t h e s e c o n d a n d t h u s u n i f o r m t r e a t m e n t i s p o s s i b le .

4 . 7 .3 P o t t i n g o f w o o l l e n f a b r i c

C r a b b i n g i s f r e q u e n t l y f o l l o w e d b y s t e a m i n g o r b l o w i n g w i t h s t e a m a n d t h e

w o o l f a b r i c s a r e g i ve n s u r f a c e s t a b i l i ty w i t hou t l o s ing t he i r s ha p i ng c a pa c i t y i n t he

m a k i n g u p p r o c e s s . T h e b o n d s t h a t st a b il is e w o o l f ib r e s in a p a r t i c u l a r c o n f i g u r a -

t io n a r e d i s u l p h i d e c r o s s -l i n k s , h y d r o g e n b o n d s , e l e c t ro s t a ti c b o n d i n g b e t w e e n a n -

i on i c a nd c a t i on i c s i de c ha i ns a nd hyd roph ob i c s i de c ha i ns i n t he p ro t e i n m ol e c u l e s

( Ta b l e 4 . 13 ) . I n t he s e t t ing p roc e s s , t he s t re s s e s a re r e l a xe d w i t h i n t he f ib r e by

m o b i l i z i n g o n e o r m o r e v a r i o u s c r o s s - li n k i n g b o n d s a n d t h e r e b y a l l o w i n g t h e m to

r e a r r a ng e i n t o ne w , uns t r e s s e d pos i ti on . The a c t i on o f s te a m on s t r a i ne d w o o l f i b re

i s t w o- fo l d [ 40 ] . Th e f ir s t s t a ge c ons i s t s o f b r e a k i ng t he e x i s t i ng bo nds 9

R - S - S - R + H2 0 --+ R - S H + R - S - O H

T h e s e c o n d s ta g e c o n s is t s o f a f o r m a t i o n o f n e w b o n d s 9R - S - O H + R - N H 2 --~ R - S - N H - R + H 2 0



Scouring 111

T A B L E 4 .1 3 .

T h e C r o s s - li n k s i n W o o l a n d R e a g e n t s C a p a b l e o f M o b i l i z in g E a c h T y p e a n dB r in g ing A bou t S t r e s s - r e l a xa t ion o r S e t t ing [39] .

C r oss - l ink M o b i l iz i n g a g e n t s

Disu lph ide l i nks

IC = O 0 = ~

I |

H C - CH 2 - S - S - CH~ - CHI ~

yi-iI I

H y d r o g e n b o n d sI _1_

C = O ................................. HNI I

Ele c t r os t a t i c bonds

IC = O O = ~

IH C - R ~ - C O O - . ....... N H 3 - R 2 - ~ H

N HI I

R~ & R 2 = h ydr o c a r bo n un i t s

H y d r o p h o b i c b o n d s

iC = O O - ~

IH C - R 3 . . . . . . . . . . . . . . . . . . . . . . . . R 4 - ~ H

N HI I

R 3 & R 4 = h y d r o c a r b o n s id e c h a in s

Th iog lyc o l i c ac id , r e duc ing a ge n t s ,

a lka l i e s , s t e a m a t h igh p r e s su r e o r

s t e a m a t a tm osphe r i c p r e s su r e f o r

long pe r iods o f tim e .

W a t e r , s t e a m o r h y d r o g e n b o n d

br e a k ing a ge n t s suc h a s u r e a a nd

DM F.

W a te r o r st e a m .

O r g a n i c s o l v e n t s e . g . , a l c o h o l s ,

DM F e tc.

The r e d i s t r ibu t ion o f H- bo nds i s a n a c c e p te d the o ry . Te m pe r a tu r e , p r e s su r e ,

m o i s t u r e a n d t i m e a r e th e p a r a m e t e r s w h i c h i n t r o d u c e p h y s i c a l a n d c h e m i c a l p ro -

c e s s e s in k i e r d e c a t iz i n g . T h e o p t i m u m p H f o r c r a b b i n g h a s b e e n s h o w n t o b e

a rou nd 6 [41 ] .

T h e s o - c a l l e d " d i s u l p h i d e e x c h a n g e " r e a c t i o n is a l so a c ce p t e d to d a y . W o o l is

cons t ruc ted o f a matr ix and m ic rofibr i ls . The c rys ta l l ine subs tance of the mic rof ibr i l s

i s e m be d de d in the m a t r ix , t he a m or pho us subs ta nc e . The two m or ph o log ic a l c om -ponents , d i f fe r d is t inc t ly in su lphur content . Dur ing the k ie r deca t iz ing , i t i s a s -

sum e d tha t t h i s d i su lph ide e x c ha nge , t he sp l it t ing o f d i su lph ide b r idge s , t a ke s p l a c e



112 Scour ing

f i rs t in th e m a t r i x b y m e an s o f w a te r a s a k in d o f p r e l im in a r y s t ag e. T h e s o - ca l l ed

m ic r o f ib r i l co m p o n e n t i s p l a s t i ca l ly d e f o r m ab le , i .e . t h e s e m ic r o f ib r i ls a r e p a r t i cu -l a r l y s tab i l i zed b y h y d r o g en b r id g es . S t eam can ac tu a l l y o n ly n o w a t t ack th es e

h y d r o g e n b r i d g e s , w h i c h w e r e p r e v i o u s l y m a s k e d b y a c o m p l i c a t e d s y s t e m o f

d i s u lp h id e b r id g es . T h e im p o r t an t s t ep th e r e f o r e i s t h a t t h e m ic r o f ib r il s a r e d e -

f o r m e d 9 h en b y co o l in g , o x id a t i o n an d t h e b lo w in g t h r o u g h o f a i r, th i s s e t m i -

c r o f ib ri l co n d i t io n i s r e - l o ck ed b y t h e r eo r g an i s ed d i s u lp h id e b r id g es i n t h e m a t r i x .

F ig . 4 - 1 3 s h o w s h o w a f t e r t h e d i s u lp h id e i n t e r ch an g e an in i t ia l ly t en s e m o lecu l a r

s t ruc tu re goe s in to r e lax ed (s tab i l i sed) s ta te in a new , geom et r ic s t ruc tu re .

1

~ - S S

SH

2

F ig u r e 4 - 1 3 . E x ch an g e o f s u lp h id e an d r e l ax a t i o n o f t h e ten s io n s [ 42 ]

1 , i n t e r n a l ex c h an g e a t t h e p r o g r es s iv e r e l ax a t i o n o f t h e t en s io n an d

2 , f ina l s tage wi thou t tens ion .

In ac tu a l p r ac t i ce t h e f ab r ic i s w o u n d o n a p e r f o r a t ed r o l l e r o r cy l i n d e r co v e r ed

w i th co t t o n c lo th to p r ev e n t th e p e r fo r a t i o n m a r k in g . Be tw een each l ay e r o f w o o l

fabr ic there i s a s imi lar th ickne ss o f in te r leav ing f abr ic . The s team is b low n th rou gh

th e i n s id e o f th e m e ta l r o l l e r u n d e r p r e s s u r e o f 4 0 - 5 0 l b fo r 1 0 t o 1 5 m in w h i l s t th e

cy l in d e r r o t a t e s . T h e n th e ab s o r b ed s t eam i s r em o v e d f r o m th e c lo th b y b lo w in g

c o m p r e s s e d a i r t h r o u g h t he f a b ri c i n m u c h t h e s a m e w a y a s th e s t e a m w a s b l o w n

th r o u g h i t. T h e a i r a l s o p r o d u ces s o m e co o l in g o n t h e fab r ic . T h e c lo th is t h en

w o u n d o n a s eco n d s t eam in g cy l i n d e r s o t h a t o u t e r l ay e r o f t h e c lo th f o r m s t h e

in n e r l ay e r o f t h e ro l l an d is s t eam e d a s b e f o r e . T h e c lo th i s t h en co o l ed o r p as s ed



Scour ing 113

th r o u g h co ld w a te r i n o p en w id th o r s q u eezed . P o t t i n g a ls o g iv es s o ft h an d l e an d

b r ig h t f in i s h . T h e m a in d i s ad v an t ag e i s t h a t s team in g a t h ig h t em p er a tu r e s t en d s toy e l l o w t h e w o o l .

4 . 7 .4 S c o u r i n g o f w o o l f a b r i c

W o o l l en f ab r ic s a r e s ti ll m o s t l y l u b r i ca ted w i th o l e in - b as ed p r o 'd u c t s o r m in e r a l

w o o l o i ls . W o r s t ed m ay b e l u b r i ca t ed a s in f o r m er t im es , w i th n a tu r a l o il s o f v eg -

e t ab l e o r an im a l o r ig in , o r w i th p o ly a lk y l en e g ly co l b as ed l u b r i can t s w i th o r w i th -

o u t m in e r a l o i l ad d i t i o n s . W o o l l en f ab r i c s a r e g en e r a l l y s co u r ed u s in g s co u r in g

l iq u o r s s im i l a r to th o s e u s ed i n y a m s co u r in g . Us e o f s o ap an d s o d a is m a in ly u s ed

as s co u r in g ag en t . T h i s s y s t em h as ce r t a in ad v a n t ag es i n p r o m o t in g b u lk in g an d

g o o d h a n d l i n g .

4 .8 C a r b o n i s i n g o f W o o l

Ca r b o n i s in g i s d o n e t o r em o v e t h e ce ll u lo si c im p u r i t ie s f r o m w o o l b y t r ea tm en t

w i th ac id o r ac id p r o d u c in g s a lt s . Ca r b o n i s in g m ay b e ca r r i ed o u t i n l o o s e w o o l o r

o n p i ece g o o d s a f t e r s co u r in g . Ho w e v er , i t i s co m m o n p r ac t i ce t o ca r b o n i s e w o r -

s t ed p i ece g o o d s a s w e l l a s w o o l l en s .

T h e co n v en t io n a l c a r b o n i s in g p r o ces s co m p r i s e s f iv e m a in s t ag es : s co u r in g ,ac id i z in g , d r y in g an d b ak in g , b u r r c r u s h in g an d d ed u s t i n g an d n e u t r a l i si n g [4 3 -4 6 ] .

W o o l p i ec e g o o d s a r e t rea t ed w i th s u lp h u r i c ac id (6 -8 o T w ) co n t a in in g ac id s t ab l e

w e t t i n g ag en t an d h y d r o ex t r ac t ed . T h e t r ea t ed w o o l s u b s t an ce i s d r i ed a t l o w t em -

p e r a tu r e (60 -70~ v e r y q u i ck ly to m in im i s e d eg r ad a t i o n b y s u lp h u r i c ac id o f i n-

t e r m ed ia t e c r i ti ca l co n cen t r a t i o n [47 ]. T h e d r i ed w o o l is t h en h ea t ed a t 1 1 0~ f o r a

s h o r t t im e . T h e g o o d s a r e t h en n eu t r a l i s ed im m ed ia t e ly o r r u n d r y t h r o u g h a d o l ly

o r m i l li n g m a c h i n e t o r e m o v e t h e c h a r re d v e g e t a b l e m a t t e r a n d t h e n n e u t r a li s e d .

N e u t r a l i s a t i o n o f w o o l f ab r ic can a l s o b e ca r r i ed o u t i n o p en - w id th s co u r in g m a-

c h i ne . N e u t r a li s a t io n w i t h a m m o n i a o r a m m o n i a / a m m o n i u m a c e t a te m i x t u re s re -

m o v es ac id f r o m th e f ab r i c f a r m o r e r ap id ly t h an e i t h e r s o d iu m ca r b o n a t e an d

s o d iu m ace t a t e .

In a r ap id ca r b o n i s in g p r o ces s [ 48 ] w o o l i s t r ea t ed i n u p t o 8% (w / v ) s u lp h u r i c

ac id s o lu t i o n f o r 3 0 s ec an d tim e d e l ay o f ab o u t 1 0 -1 5 m in i s in t r o d u ced b e f o r e

d r y in g . T h e l o ca l l y d a m ag e d a r eas can g r ea t l y w e ak e n t h e fi b re i f s u r f ace ac id is

no t even ly d i s t r ibu ted [49] dur ing d ry ing . Ho we ver , in the r ap id carbon is ing m ethodw i th a d e l ay o f 1 0 -1 5 r a in , th e d i s t r i b u t io n o f su lp h u r i c ac id b e tw een s u r f ace ac id



114 Scour ing

and to ta l ac id ins ide the wo ol chan ges [50 ] . Free sur face ac id pene t ra te in to the

wo o l f ib r e s a nd bonds to woo l . Thus the a m o un t o f c onc e n t r a t e d a c id f o r m e d du r -

ing d r y ing a nd ba k ing i s m in im ise d a nd a s a c onse que nc e , l e s s c he m ic a l a t t a c k

oc c ur s to woo l in r a p id c a r bon i s ing .

M a gn e s iu m c h lo r ide , a lum in ium c h lo r ide ( 8 - 10 ~ Tw ) o r ga se ous hyd r oc h lo r i c

a c id m a y a l so be use d f o r c a r bon i s ing o f woo l . R a gs a r e c a r bon i se d to r e m o ve

c o t ton s t i t ch ings p r io r t o u se in sha ddy by the ' d r y c a r bo n i s ing ' p r oc e s s by e xp os -

ing to hydr oc h lo r i c a c id ga s in a n e nc lose d c ha m b e r . M e ta l a c id sa lt s l i be ra t e

hyd r oc h lo r i c a c id a t h igh t e m pe r a tu r e a nd a t t a c k the c e l lu lose in woo l . B u t ow ing

to the ir h igh c os t a nd h ighe r t e m p e r a tu r e s r e qu i r e d w h ic h c a use in ju r y to d r y woo l ,

a re ra re ly used .The w oo l bu r r s c on ta in he m i - c e l lu lose a nd lign in a pa r t f r om c e llu lose. The

l ign in i s no t e f f e c t e d by c a r bon i s ing p r oc e ss on a c id hydr o lys i s , bu t c a n be sp l i t

ox ida t ive ly . S a l t o f pe r su lphu r i c a c id a c c e ler a t e s de g r a da tion o f woo l bu r r s wh ic h

e na b le sho r t e n ing the t im e o f r e a c t ion [51 ] .

Na tu r a l so i l ing o f woo l a nd ve ge ta b le m a t t e r a nd sk in fl a kes , c a n a l so be e nz y-

m a t i c a l ly m od i f i e d [52 ]. The re p la c e m e n t o f c a r b on i sa t ion by the use o f e nz ym e s ,

such as ce l lu lases , l igninases , hydrolases , lyases , oxidoredulases e tc . a re repor ted

[53 ] . The m a in a dva n ta ge s o f e nz ym a t i c c a r bon i s ing a r e r e duc e d w oo l f ib re da m -a ge , e f f lue n t l oa d a nd e ne r gy c on sum p t ion .

C a r bo n i se d woo l a r e m o r e po r ous tha n sc our e d woo l a nd he nc e the dye up ta ke

i s h ighe r . Un e ve n dye ing m a y r e su l t due to fa u l ty c a r bon i s ing [54 ].

4 .9 D e g u m m i n g o f S i lk

D e g u m m i n g o r b o i l i n g - o f f i s t h e p r o c e s s e m p l o y e d t o r e m o v e t h e s i l k g u m

(ser ic in) enve lo pin g the two raw s i lk threads ( f ibr ion) (Fig . 4-14) . Du r ing the

F igur e 4 - 14 . The m ic r o pho togr a ph o f r a w s i lk [55 ].



Scour ing 115

sp inon ing p r oc e ss o f s i lk by s i lkwor m s the two f i l a m e n t s a r e m a de in to one by

m e a ns o f p r o te in ious gu m m y subs ta nc e c a l l e d se r ic in . The gu m c on te n t o f s i lk

va r i e s a c c o r d ing to qua l i ty a nd o r ig in . B o m by x m or i o r M u lbe r y s i lk s ha ve a bou t

2 0 - 3 0 % g u m a n d T u s s a h 5 - 1 5 % . T h e g u m i s n o t c o m p l e t e l y r e m o v e d i n e v e r y

c a se. The e x te n t o f de g um m ing g ive s r i s e to d i f f e r e n t va r i e t ie s o f s i lk [56] . ' Ec r u

s i lk ' ( c r ude , ba s t s i lk ) i s r a r e ly de gum m e d , qu i t e ha r d a nd wi thou t lu st re . The

d e g u m m i n g l o s s i s m a x i m u m 4 % , s i n c e m o s t l y o n l y g r e a s e , w a x a n d r e s i n s u b -

s t a nce s a r e r e m ove d . Th i s type o f s i lk is m a in ly use d a s wa r p th r e a ds. ' Ha l f - bo i l e d

s i lk ' ( soup le , so ft , m a t t s il k ) i s pa r t i a l ly de gum m e d . The d e gu m m ing lo s s is a p -

p r ox im a te ly 6 - 12%. I n o r de r to m a ke the gum on the fib re to so f t en a nd r e m a in intha t c ond i t ion , a t r e a tm e n t o f 3 - 4% of t a rt a r e m a t i c i s adv i sa b le . ' C u i t e s i lk ' ( l u s t re

s i lk ) w i th ne a r ly 18 - 30 % gum los s c a n be c l a s s i f i e d a s a c om ple te ly de gum m e d

va r i e ty w i th a so f t ha nd le a nd h igh lu s tr e .

Apar t f rom se r ic in , o the r impur i t ie s present in s i lk a re lubr icants and sof teners

added dur ing throw ing or in prepara t ion for we aving or kni t t ing , d i r t and o i l s p icked

up inc ide n ta lly du r ing p r oc e ss ing a nd unde s ir a b le na tu ra l c o lou r s . The c om pon e n t

o f fa t s a nd o i l s i s a r ound 0 .5 - 1% a nd tha t o f na tu r a l p igm e n t s 1 .0 -1 .4%. Dur ing

the deg um m in g proc ess , so i l , s ta in , o il and fa ts s t ick ing to the m ate r ia l w i l l a lso ber e m o v e d . T h u s d e g u m m i n g i s s y n o n y m o u s w i t h t h e s c o u r in g p r o c e s s n o r m a l l y

use d f o r the pu r i f i c a t ion o f c o t ton a nd woo l .

S i lk wa r p i s no t sub je c t e d to s i zing be f o r e we a v ing l ike c o tton . How e ve r , g r e y

s i lk f a b r i c a nd i t s b l e nde d f a b r i c s a r e sub je c t e d to s inge ing p r io r to de gum m ing .

De gum m ing c a n be c a r r i e d ou t by phys ic a l o r c he m ic a l m e a ns on s i lk in the f o r m

of ha n k a nd a l so on f a b ri c s wh ic h a r e subse que n t ly t a ke n f o r dye ing . The c ho ic e o f

de g um m ing c ond i t ions de pe nds on the type o f s i lk p r odu c t ( ya m , tw i s t , f a b r ic s o f

d i f f e r e n t de ns i ti e s ). W i ld s i lk fa b r ic i s m o r e d i f f i c u lt to de g um tha n M ulbe r y s ilk .

Tuss a h s i lk c on ta ins h ighe r qua n t i t i e s o f c a l c ium sa lt . L oss in we igh t o f s ilk by

d e g u m m i n g p r o c e s s i s a ls o a c c o m p a n i e d b y a l o ss i n s tr e n g th o f ap p r o x i m a t e l y

2 0 % . T h e l o s s o f w e i g h t a n d v o l u m e c a n b e c o m p l e t e ly o r p a rt i a ll y c o m p e n s a t e d

by the subse que n t we igh t ing p r oc e ss .

De gum m ing i s e f f e c t e d by c a r e f u l t r e a tm e n t o f s i lk w i th h igh p r e s su r e wa te r ,

ac ids , a lka l ie s , soaps and synthe t ic de te rgents . Ch em ica l d isso lu t ion of se r ic in i s

ob ta ine d pa r t ly by hydr o lys i s a nd pa r tly by d i spe rs ion , i nde p e nde n t o f t he m e thod

use d . S oa p wor ks m a in ly by d ispe r s ion wh i l s t a lka l i e s ha ve a s t r ong hydr o ly t i c

effect [57].



116 Scour ing

4 . 9 . 1 D e g u m m i n g o f s i l k i n w a t e r [ 5 8 ]

Cu l t i v a t ed v a r i e t i e s o f s i lk can b e d eg u m m ed b y ex t r ac t io n w i th w a te r a t 1 20~f o r ab o u t 2 h an d r ep ea t i n g t h e p r o ces s t h r ee t o f o u r tim es . In t h is ca s e d e g r ad a t i o n

o f si l k i s m in im u m , b u t u s e o f p r e s s u r e eq u ip m e n t i s e s s en t ia l . Ho w e v er , s o m e

m o d i f i ca t i o n o f t h e p r o t e in m o lecu l e d o es t ak e p l ace .

4 . 9 .2 D e g u m m i n g o f s i lk w i t h a l k a l i [ 5 9] a n d a c i d [ 60 ]

Si lk d eg u m m in g in aq u eo u s s o lu t io n s o f ac id s an d a lk a l i e s is g r ea t ly i n f lu en ced

b y p H a n d t em p er a tu r e . An a lk a l i n e reac t i o n a t a p H > 9 an d ac id r eac t i o n a t

p H < 2 . 5 en s u r e a r ap id e l im in a t i o n o f se r i c in co m p le t e ly a f t e r 3 0 m in o f t r ea tm en t .

T h e t em p er a tu r e s h o u ld n o t ex ce ed 95 ~ to av o id w e ak en in g o f t h e f ib r e . T h e

d eg r ee o f h y d r o ly s i s o f fi b r io n a l s o d ep e n d s o n p H o f t h e b a th .

4 . 9 .3 D e g u m m i n g o f s i lk w i t h s o a p [61 ]

D e g u m m i n g is e ff e c te d b y c a r e fu l b o i l i n g - o f f i n so a p b a th s w h i c h s h o u l d b e

s l igh t ly a lka l ine . The f ib re i s t r ea ted w i th soap so lu t ion to g ive a pH arou nd 10 .0 a t

90-95~ fo r 1 .5 -2 h . In o rder to avo id l i en soap depos i t s and r esu l t ing s ta ins , the

w a te r s h o u ld b e p r o p e r ly s o f t en ed . Seq u es t e r i n g ag en t m ay b e ad d ed i n t h e b a th t o

co r r ec t t h e h a r d n es s o f w a t e r . In ca s e o f w h i t e an d d e l i ca t e v a r i e t ie s a tw o b a thm e t h o d m a y b e e m p l o y e d . T h e s e c o n d d e g u m m i n g b a th w i ll c o n si s t o f 5 0 % q u a n -

t i ty o f s o ap t ak en f o r t h e f ir s t d eg u m m in g b a th an d t h e d u r a ti o n o f tr ea tm en t m ay

b e d iv id ed eq u a l ly b e tw een 4 0 - 4 5 m in f o r each b a th .

N e u t r a l s o ap l i k e M er s e i l le s o ap o r o li v e o il s o ap h av e n o d eg u m m in g p r o p e r ty

as t h e f r ee a lk a l i p r e s en t i n t h em a r e v e r y n eg l ig ib l e . Ho w ev er , Mer s e i l l e s o ap

(8 g /l ) can b e u s ed i n p r e s en ce o f n o n - io n i c t en s id e ( f a t ty a l co h o l p o ly g ly co l e th e r )

(1 -3 g / l ) , po lyp hos pha te (1 -3 g / l ) ( fo r so f ten ing the w ater ) and sod a (1 g / l ) a t 95~

for 1 -2 h wi th a m ater ia l to l iquor r a t io o f 1 :30 . Here a l so a two ba th m etho d can be

r e s o r t ed t o . N o n - io n i c t en s id e acce l e r a t e s t h e d eg u m m in g p r o ces s an d fac i l it a t e s

r i n s in g o u t t h e s o ap . T u s s ah s i l k i s u s u a l l y p r ew e t t ed w i th b o i l in g w a te r b e f o r e

d e g u m m i n g a n d t h e n d e g u m m e d i n st ro n g a l k a li n e b a th [ 62 ].

4 .9 . 4 D e g u m m i n g o f s il k w i t h s y n t h e ti c d e t e r g en t s

D e g u m m i n g w i t h s y n th e t ic d e t e r g e n t is i n c r e a s in g l y re p l a c i n g s o ap . T h e m a i n

d r aw b ack s a r e s o ap i s ex p en s iv e , g r ea t q u an t i t y o f s o ap i s r eq u i r ed an d l o n g e r

t r ea tm en t t im e . A l a rg e n u m b er o f s y n th e t ic d e t e r g en t s a r e av a i lab l e i n t h e m ar k e tan d t h e i r s e l ec t i o n i s v e r y im p o r t an t p a r t i cu l a r ly o n t h e r eq u i r em en t o f s o ft f ee l a s



Sc o u r i n g 1 1 7

t h a t a c h i e v e d w i t h s o a p . N o n - i o n i c p r o d u c t l i k e n o n y l p h e n o l e t h o x y l a t e d c o m -

p o u n d i n t h e p H r a n g e o f 1 1 .2 - 1 1 .5 f o r a t r e a t m e n t t im e o f 4 0 m i n a t 95 ~ i s f o u n d

t o r e m o v e t h e g u m a n d m a i n t a i n t h e s t r e n g th o f t h e y a m .

4 .9 .5 E n z y m a t i c d e g n m m i n g o f s i lk

E n z y m e w h i c h c a n h y d r o l y s e t h e s e r i c i n i s c l a s s i f i e d a s p r o t e o l y t i c e n z y m e s

[ 6 3 - 6 5 ]. T h e p r o t e o l y t ic e n z y m e s c l e a v e t h e p e p t i d e / a m i d e l in k a g e s a n d c o n v e r t

t h e m i n to a m i n o a c id . M a i n l y t h e re a re t h r e e t y p e s o f p r o t e o l y t i c e n z y m e s s u c h a s

z i n c p r o t e a s e ( e. g . c a r b o x y p e p t i d a s e A ) , s er in e p r o t e a s e ( C h y m o t r y p s i n , T r y p s i n ,

T h r o m b i n ) a n d t h i o l p r o t e a se ( a c ts a s c y s t i n e r e s i d u e i n t h e p r o t e i n ) . T h e f u n c t i o n

o f p r o t e o ly t ic e n z y m e s in t h e ir d e g r e e o f d e g u m m i n g d e p e n d s o n t h e p H o f t heb a t h a n d t h e o p t i m u m a c t i v i t y is f o u n d t o b e d i f f e r e n t a t d i f f e r e n t p H f o r d if f e r e n t

e n z y m e s .

U s u a l l y e n z y m a t i c d e s i z in g o f s i lk is a t w o s t a g e p r o c e s s . I n p r e - d e g u m m i n g

s t a g e , t h e c l o t h is t r e a t e d w i t h a so l u t i o n c o n t a i n i n g so d a - a sh ( 1 g /l ) a t 95 ~ f o r 2 0

m i n a t a l iq u o r r a t io o f 3 0. I n t h e s e c o n d s t a g e, f u r t h e r d e g u m m i n g i s c a r r i e d o u t b y

t r e a t m e n t i n a so l u t i o n c o n t a i n i n g p r o t e i n e n z y m e ( 0 .06 - 0 .1 g / l ) , n o n - i o n i c d e t e r -

g e n t (1 g / l) fo r 3 0 m i n a t 5 5 t o 60~ I t i s u su a l l y i m p o ss i b l e to a c h i e v e f u ll d e g u m -

m i n g o f si l k b y e n z y m e s . A sh o r t - t i m e t r e a t m e n t in a t h i r d b a t h c o n t a i n i n g so d a - a sho r s o a p m a y b e g i v e n f o r th e r e m o v a l o f t h e r e m a i n i n g s e ri c in .

4 . 9 . 6 F o a m d e g u m m i n g

T h e d e g u m m i n g o f s il k c a n a ls o b e ca r r ie d o u t b y f o a m m e t h o d . T h e s i lk s k ie n s

a r e su b j e c t e d t o t h e a c t i o n o f f o a m f r o m a b o i l i n g so a p b a t h . Sk i e n s a r e a c t u a l l y

h u n g a b o v e t h e s o a p s o l u t i o n a n d t h e f o a m a c t i o n h a s a t e n d e n c y t o d i s s o l v e a n d

e l i m i n a t e s e r ic i n . T h i s m e t h o d , h o w e v e r , i s n o t p o p u l a r l y a d o p t e d .

4 .9 . 7 P a r t i a l d e g u m m i n g o f s i l k

B e f o r e p a r t i a l d e g u m m i n g t h e s i lk i s d e g r e a s e d i n m o d e r a t e l y w a r m ( 3 0 -4 0 ~

a n d s l i g h t ly a l k a l in e s o a p b a t h s. T h e a c t u al d e g u m m i n g is t h e n t a k e n p l a c e in a

b a t h c o n t a i n i n g a c i d s a l ts o r a c i d s . T h e s e r i c in is n o t r e l e a se d a s m u c h i n an a c i d

m e d i u m a s i t i s i n a n e u t r a l o r a l k a l i n e b a t h , t h u s o n l y p a r t i a l d e g u m m i n g r e su l t s .

A c i d d e g u m m i n g h a s a l s o a p o s i t i v e e f fe c t o n t h e s tr e n g t h a n d h a n d l e . T h e a c t u a l

d e g u m m i n g b a t h c an h a v e v ar io u s c o m p o s i t io n s :

- S u l p h u r i c a c i d a n d m a g n e s i u m s u l p h at e ,

- Su l p h u r i c a c i d a n d so a p ,

- Su l p h u r i c a c i d a n d t a rt a r ,

- 4 % s t r e n g t h so a p so l u t i o n ,

- N a H S O 3 s o l u ti o n .



118 Scour ing

De pe n d ing on the na tu r e o f s ilk , it is t re a t e d f o r 1 -3 h a t bo i l ing t e m p e r a tu r e . The

w e igh t lo s s w i th ha l f bo i l e d s i lk l ie s in the r a nge o f 6 -12% on the o r ig ina l r aw

weight .

4 .9 .8 W a s h i n g o f d e g u m m e d s il k

Af te r bo i l ing - o f f , t he s i lk i s t ho r ough ly wa she d wi th lo t o f wa te r a t 50 - 6 0 ~

c on ta in ing lm l /1 a m m onia f o r 15 -20 m in . Th i s i s t he n f o l low e d by 1 to 2 c o ld

r in s ing ba ths . Ha l f - bo i l e d s i lk shou ld no t be sub je c t e d to ho t soa p ba ths a nd a lka -

l ine li quor s ov e r 30~ be c a u se th is wou ld a c t on the s i lk gum s t i ll p r e se n t .

Fo l lo w ing w a sh in g a nd d r y ing s i lk i s g ive n f u r the r m e c ha n ic a l t r e a tm e n t in the

f o r m o f s t r e tc h ing , be a t ing o r g los s ing . S c r oop i s im pa r t e d to the s i lk fa b r i c by

t r e a tm e n t w i th 2 - 5 g /1 o f 30 % a c e t i c a c id a t r oom te m pe r a tu r e f o r 15 - 30 m in . W he n

s i lk is de l ive r e d in dye d c ond i t ion , s c r oop ing i s done a f t e r dye ing .

Bo th deg um m ing and par t ia l deg um m ing a re only su i tab le for ree led s i lk (gre ige) .

The se f in i sh ing p r oc e sse s a r e in s ign i f i c a n t whe r e sc ha ppe a nd bour e t t e s i lk s a r e

c onc e r ne d , s inc e the se a re f r e e d f r om the i r gum in the e a r ly s t a ge s o f p r e pa r a t ion

be f o r e sp inn ing [66 ].

4 .1 0 D e g u m m i n g o f R e m i eD e g u m m i n g o f r e m i e is a l o n g a n d c o m p l e x p ro c e d u r e . D i f f e re n t d e g u m m i n g

techn olog ies [67-72] use d i f fe rent auxi l ia r ie s . Bes id es boi l ing-of f , o the r t r ea tme nts

suc h a s s c u th ing , w a sh ing in a c id so lu t ion a n d wa te r e tc . d i r e c tly e f f e c t the she e n

a n d g u m c o n t e n t o f t h e m a s s o f c l e a n e d f i br e.

I n c he m ic a l de g um m ing o f r e m ie , ho t c a us t ic soda so lu t ion o f a bou t 10 % ( o.w .f .)

i s u se d to d i s so lve pe c t i c subs ta nc e s . Apa r t f r om th is , sod ium phosph a te , sod ium

pyr o pho sph a te , sod ium m e ta s i l ic a t e , sod ium su lph i t e c a n a lso be use d f o r de gu m -

m i n g o f re m i e .

S o d i u m p y r o p h o s p h a t e i s b e t t e r t h a n s o d i u m p h o s p h a t e i n w a s h i n g a n d t o ta l

c l e a n ing [7 3 ] . A l thou gh sod ium pyr op hos pha te is ve r y pe r m e a b le , d i f fus ib l e a nd

c a n sc ou r a s we l l i n p r e se nc e o f m e ta l i ons , i t i s e xpe ns ive . S od ium m e ta s i l i c a t e

shows good wa sh ing , t o t a l c l e a n ing a nd e m uls i f y ing p r ope r t i e s a nd i t i s i ne xpe n-

s ive . S odium sulphite , not only has a b leaching func tion , but a lso pro tec ts the phys ica l

p r ope r t i e s o f t he f ib r e s . The d e gu m m ing e f f ic i e nc ie s o f t he se th r e e a ux i l i a ri e s wa s

s tud ie d by us ing qua dr a t ic o r thogona l r o t a t ion e xpe r im e n ta l de s ign [7 4 ]. The c on-c e n t r a t ion o f a ux i l i a r i e s a nd t im e o f s e c ond bo i l ing - o f f a r e the m os t im por t a n t



Scour ing 119

f a c to r s in d e g u m m i n g . S o d i u m p y r o p h o s p h a t e c a n b e re p l a c e d a n d re p l e n i s h e d b y

sod ium m e ta s i l i c a t e ove r a de f in i t e ra nge , so al so de c r e a se the m a nu f a c tu r ing c os t.T h e o p t i m u m c o n d i t io n s o f s o d i u m s u l p h i te d e g u m m i n g a r e 1 % a n d s e c o n d b o i l-

ing - o f f t im e , 3 - 3 .5 h , t he c onc e n t r a t ions o f sod ium m e ta s i l ic a t e a nd py r o pho sph a te

a r e 2 .5 - 3% a nd 0 .7 - 1 .0 % r e spe c t ive ly .

4 .1 1 S c o u r i n g o f L i n e n

T h e s c o u r i n g o f l in e n i s a s s o c ia t e d w i t h n u m b e r o f p r o b l e m s s u c h a s w e i g h t

lo s s , r e l e a se o f c a tions f r om sa l ts i n to so lu t ion a nd lo s s in s t re ng th . I f t he r e l e a se d

c a t ion i s i r on , t h i s c a n l e a d to c a t ion ic t e nde r ing du r ing b le a c h ing . Th i s p r ob le m

c a n be m in im ise d b y a dd ing su i t a b le c he la ting a ge n t s in the sc our ing ba th a nd thus

se que s t e r s a n y c a t ions r e l e a se d f r om the p r o te ins .

T r a d i t iona l ly , l ong s low p r oc e ss e s a r e c a r r ie d ou t t o ob ta in c o r r e c t ba l a nc e be -

twe e n the re qu i r e d p r op e r t i e s o f wh i t e ne ss , a bso r ba nc y e tc . in one ha nd a nd c he m i -

c a l da m a ge o n the o the r. The t r a d i t iona l p r oc e s s u su a l ly c ons i s t s o f c h lo r ina t ion ,

e x t r a c ti o n o f t h e c h l o r in a t e d l ig n i n b y s c o u r in g i n s o d a - a s h a n d t h e n b l e a c h i n g

pr e f e r a b ly w i th a l t e r na te c h lo r it e a nd pe r ox ide s t a ge s o r e ve n hypoc h lo r i t e b l e a c h .

P r oc e ss de ta i l s o f c onv e n t iona l m e th od a r e show n in Ta b le 4 .14 . L im e bo i l isT A B L E 4 . 1 4

C o nve n t iona l P r oc e ss De ta i ls f o r t he S c our ing o f F la x

Kie r bo i l L im e 10 - 12% ( o .w . f .) ,

8 h at 60~

C is t e r n sou r

Kie r bo i l

C i s t e rn c h e m i c

Kie r bo i l

C h e m i c b l ea c h

Sod a-ash 12 .5 g / l , 18 h

at 60~A va ilab le C12 1.7 g/l, 2 h at

pH 4 .3

So da-a sh 6 .5 g/ l , 18 h

at 60~

Av ailab le C12 0 .6 g/ l , cold

p a d - b a t c h

ove r - n igh t

So da-a sh 2.0 g/1



120 Scour ing

f o l l o w ed b y h y d r o ch lo r i c ac id s o u r , a l k a l i n e ( s o d a - a s h ) b o i l s , a c id ch em ic (h y -

p o ch lo r i t e a t p H 4 t o 5 ), a f u r th e r a lk a li n e b o i l w i th s o d a - a s h w h ich r em o v e s t h ech lo r in a t ed s p r it ( r em n an t s o f th e w o o d y co r e o f t h e f lax s t em ) , an d f i n a l l y a h y -

p o ch lo r i t e b l each (p H 9 - 1 0 ). T h i s co m p l i ca t ed p r o ces s s eq u en ce h as b een s t r eam -

l in ed o v e r t h e y ea r s . T h e l im e b o i l h a s b een r ep l aced b y a cau s t i c - s o d a - a s h b o i l.

4 . 1 2 S c o u r i n g o f J u t e

Although ju te i s a na tu ra l f ib re l ike co t ton , i t d i f f e r s in chemica l compos i t ion .

Un l ik e co t t o n j u t e co n t a in s a h ig h p e r cen t ag e o f n o n - ce l l u lo s ic m a t t e r ( ab o u t 4 0%)

an d th e p r e - t r ea tm en t p r o ce s s es o f j u t e a r e s o m e w h a t d i f fe r en t f ro m th a t o f co t t o n .

Sco u r in g o f ju t e w i th cau s t ic s o d a u n d e r p r e s s u r e can n o t b e ca r r ied o u t li k e co t to n

b ecau s e o f r em o v a l o f h em i - ce l l u lo s e w h ich r e s u l ts i n h ig h l o s se s o f ten s i le s t r en g th

( 1 0 - 1 5 % ) a n d w e i g h t ( 6 - 8 % ) .

Ap ar t f r o m n a tu r a l im p u r i t i e s , j u t e y a r n s o r f ab r i c s co n t a in m in e r a l o i l / j u t e

b a t ch in g o i l ( JBO ) , w h ich i s ad d ed t o f ac il it a t e s p in n in g o f ju t e f ib r e . T h e J B O h as

a d e lu s t e r i n g e f f ec t an d a ls o co n t r i b u t e s ad d i t io n a l y e l l o w in g o n ex p o s u r e t o li g h t.

Des p i t e g o ld en b r o w n co lo u r o f j u t e an d p r e s en ce o f m in e r a l o i ls i t i s d i r ec t ly

t ak en f o r b l eac h in g a f t e r a h o t an d co ld r i n s e o r an ac id s t eep in g o r a n eu t r a l / m i lds co u r in g . T r ea tm e n t w i th d il u te s o lu t i o n o f s o d iu m h y d r o x id e an d s o ap a t e l ev a t ed

t em p er a tu r e r e s u l t s i n s o ft e r f ee l an d p l i ab i li t y w h ich m ay b e a t t r ib u t ed t o th e ac -

t ion o f a lka l in i ty in the soap and depos i t ion o f f a t ty mater ia l s on the f ib re su r face .

An e f f ec t i v e m e th o d o f r em o v a l o f J BO o r m in e r a l o il t o g e th e r w i th ad h e r in g /

ex t r en e o u s d i r t s /im p u r i ti e s i s t o tr ea t th e g r ey m a te r i a l w i th an em u l s i f ied s o lv en t

f o r 1 5- 2 0 m in at 70 -80~ to w h ich s o d a - a s h m ay o p t io n a l l y b e ad d ed . T h e ad v an -

t ag e o f t h e p r o ces s i s t h a t t h e s t r en g th o f j u t e i s n o t a f f ec t ed m u ch .

4 .1 3 S c o u r i n g o f S y n t h e t i c - p o l y m e r F i b r es

Synthe t ic f ib res gene ra l ly do no t con ta in na tu ra l ly occur ing im pur i ties l ike na tu ra l

f ib res i. e . co t ton and wool . Ho w eve r , sp in fin i shes , p roc ess ing an d con ing o i l s and

an t i s ta t i c ag en t s a r e ad d ed to im p r o v e t h e p h y s i ca l an d m ech an ica l p r o p e r t i e s d u r -

i n g s p in n in g , w eav in g an d k n i t t i n g . O th e r im p u r i t i e s a r e d i r t an d s ig h t in g co lo u r s

( to d i s t i n g u i s h o n e k in d o f fi b re f r o m th e o th e r ). T h e o b j ec t i v e o f s co u r in g s y n -

the t ic f ib re f abr ics i s to r emove the d i r t , s ize , p rocess ing lubr ican ts and s igh t ing

co lo u r s , a ch i e v em en t o f r e l ax a t i o n i n t h e ca se o f t ex tu r i s ed an d k n i tt ed f ab r i c s an dp r o d u c t io n o f s p ec i a l e f fec t s .





122 S c our i ng

T A B L E 4 .1 5

R e c i p e s f o r t h e S c o u r i n g o f N y l o n s

S c o u r i n g c h e m i c a l B a t c h p r o c e s s C o n t i n u o u s p r o c e s s

N o n- i on i c de t e rge n t ( g /l ) 2 -3 2 -3

An ionic de te r gen t (g / l) 1-2 1-2

So da- ash (g / l) 1-3 -

S o d i u m p y r o p h o s p h a t e ( g /l ) - 3 - 6

Te m pe ra t u r e ( ~ 7 0 9 0

T i m e ( mi n) 20 -30 10 -20

be o f a s s i st a nc e i f o i l s t ai n is a l s o be r e m ov e d f rom t he fi b re . The t e m pe ra t u r e o f

s c our i ng de pe n ds on w he t he r t he ma t e r i a l ha s be e n he a t - s e t o r no t . Fo r uns e t f a b r ic

the pre fe ra ble t em per a ture ra ng e i s 70-80~ and for the se t fabr ic it i s 95-100~

U ns e t f a b r i c s ha ve c r e a s i ng p rob l e m i f s c our i ng i s c a r r i e d ou t i n rope fo rm a bove

6 0~ A f t e r s c our i ng the fa b r ic is w a s he d f i r st a t r oom t e m pe ra t u r e a nd t he n r a i s e d

t o t he r e qu i r e d t e mp e ra t u r e . A n a c i d ic w a s h - o f f i s ne c e s s a ry w he n c a t i on i c f in i s h

i s t o be r e m ov e d f rom t he f a b r i c.

4 .13 .3 Scour ing o f po lyaery lon i t r i le f ibres

S c our i ng i s pa r t i c u l a r l y ne c e s s a ry fo r ya ms w h i c h a r e t o be dye d i n pa l e a nd

me d i um s ha de s a s g r e y pa t c he s ma y a ppe a r due t o s o i l i ng a nd l ub r i c a n t p r e s e n t i n

the f ibre .

B e fo re s c o ur i ng h i gh bu l k a c ry l i c ya m s on c one s a r e r e l a xe d i n s a tu r a t e d s t e a m

a t a bou t 10 0~ fo r 20 m i n o r i n ho t w a t er . The ha nks m a y be r e l a xe d du r i ng dye i n g

a l so . Fa b r i c s m a y be g i ve n d ry he a t t r e a t me n t to i mpa r t s om e s t a b il i ty a ga i ns t

c r e a s i ng a nd t o r e la x t he ma t e r i a l .A l ka l i ne s o l u t ions o r s oa ps a re no t u s e d fo r s c our i ng o fp o l ya c ry l o n i t r i l e f i b re s

as they d i sco lour the f ibre . Sco ur in g i s ca r r i ed ou t in a so lu t ion c on ta in ing 1-2 g/1

non - i on i c de t e rge n t a nd 1 g /1 t r i s od i um pho s pha t e a t bo i l f o r 30 r a in . A n i on i c de -

t e rge n t s hou l d be a v o i de d . 1 ml / 1 s o l ve n t -ba s e d de t e rge n t ma y be a dde d i n t he ba t h

fo r r e m ov a l o f oi l a nd g re a s e f rom t he f ib r e . A f t e r s c our i ng t he ba t h is c oo l e d t o

6 0~ a nd r in s e d a t t h is t e mp e ra t u r e t ho ro ugh l y t o r e m ove de t e rge n t s a s i ts p r e s e nc e

a f f e c t t he ha nd l e o f t he f ib r e .G e n e r a l l y , s c o u r i n g o f m o d a c r y l i c f i b r es is n o t a lw a y s n e c e s s a ry . H o w e v e r ,

s c our i ng a nd d e s i z i ng m a y be c a r r i e d o u t in a s i mi l a r ma nn e r t o tha t r e gu l a r a c ry l i c



Scour ing 123

f ib re s w i th n o n - io n i c d e t e r g en t s a t 5 0 - 60~ f o r 3 0 m in u n d e r e i th e r w eak ly ac id

(ace t i c ac id ) o r a lk a l i n e ( t r i s o d iu m p h o s p h a t e ) co n d i t i o n s f o l l o w ed b y t h o r o u g h

r ins ing .

4 . 1 3 .4 S c o u r i n g o f a c e t a t e f i b r es

T h e s co u r in g o f ace t a t e f i b r e s can b e ca r r i ed o u t i n a s o lu t io n co n t a in in g 3 g/1

s o ap an d 1 g /1 o f a 2 5 % s o lu t io n o f am m o n ia f o r 3 0 -3 5 r a in a t 70~ Diace t a t e can

b e s ap o n i f i ed u n d e r ce r t a in co n d i t i o n s o f a lk a l i n e s co u r in g an d t h e r e f o r e ca r e f u l

co n t r o l is n ec es s a r y t o av o id s u r f ace m o d i f i ca ti o n . De lu s t e r i n g o f n o r m a l ly b r ig h t

ace t a t e f i b re s can b e co m b in ed w i th s co u r in g . T r i ace t a t e i s n o t d e lu s t e r ed b y b o i l-

i n g o r s o ap s o lu t io n s . F o r tr i ace t a te h ig h e r t em p er a tu r e o f w e t t r ea tm e n t can b e

g iv en t h an f o r d i ace ta t e .

4 . 1 3 .5 S c o u r i n g o f r e g e n e r a t e d c e l lu l o s e

Viscose an d cupram m onium rayons do no t con ta in na tu ra l imp ur i ties and scour ing

i s d o n e o n ly t o r em o v e ad d ed im p u r i t ie s . Ra y o n can b e c lean ed b y t r ea tm e n t a t a

t em p er a tu r e o f 80 - 90~ w i th s o ap s o lu t io n (0. 3 - 0 . 5 %) to w h ich m i ld a lk a l i l ik e

s o d a - a s h o r t r is o d i u m p h o s p h a t e m a y b e a d d ed . R a y o n f a b r ic s m a y b e d e s i z e d ,

s c o u r e d a n d b l e a c h e d b y t r e a t m e n t w i th a s o lu t io n c o n t a in i n g h y d r o g e n p e r o x i d e(0 .67 vo l ) , caus t ic soda (5 g / l ) , toge ther wi th sod ium s i l i ca te (5 g / l ) and wet t ing

ag en t (1 . 5 g /l ) b y p ad - s t eam m e th o d . T h e t r ea t ed f ab r ic i s s t eam ed f o r 2 m in .

Af t e r b o i l i n g - o f f , t h e fab r i c is w a s h ed w i th w ar m an d co ld w a te r . T h e s t r en g th o f

h y d r a t ed ce l l u lo s e i s co n s id e r ab ly r ed u ced i n w e t co n d i t i o n an d h en ce s co u r in g

s h o u ld b e ca r r i ed o u t i n a ten s io n l e s s co n d i t i o n .

4 . 1 3 .6 S c o u r i n g o f t e x t u r i s e d f a b r i c

T h e f i l am en t y a r n h as an e s tab l i s h ed s u p e r io r i t y o v e r sp u n y am s d u e t o i ts h ig h

s t r en g th an d l u s tr e . Ho w e v er , f ab r i c s m ad e f r o m f i l am en t y a r n d o n o t p o s s es s a

s o f t f ee l an d ap p ea r t o b e p ap e r y . T o r em o v e t h i s d r aw b ack an d t o ach i ev e s u p p le -

n e s s in t h e f ab r ic , th e f il a m e n t y a r n is g iv e n w h a t is c a l le d a " C r i m p i n g " . T h e

p r o c e s s o f m a k i n g c r i m p y a r n i s k n o w n a s ' t e x t u r i s i n g " . T e x t u r i s i n g is p o s s i b le

f o r s y n th e t i c f i b re b ecau s e o f i ts t h e r m o p las t i c n a tu r e . T ex tu r i s i n g im p r o v es t h e

e las t ic i ty , bu lk iness , r es i l i enc y , c rea se r es i s tance e tc . o f the f abric . Fa lse tw is t p ro-

ces s es a r e w id e ly u s ed f o r t h e p r o d u c t io n o f b u lk ed p o ly es t e r an d n y lo n y am s f o r a

v a r i e ty o f en d u s es i n th e w o v en an d k n i t t ed g o o d s , i n c lu d in g s o ck s , g lo v es , k n i t t edu n d e r w e a r , m u f f l e rs , s w ea t e r s , b a th in g s u i ts an d m an y o th e r p r o d u c t s .



1 2 4 Sc o u r i n g

T h e t e x t u r e d w o v e n a n d k n i t te d g o o d s p o s s e s s l a te n t h e a t o f t o r q u e w h i c h i s

a l r e a d y s e t d u r i n g te x t u r i s i n g p r o c e s s . T h e w a r p y a m is a p p l ie d w i t h a l a r g e a m o u n to f s i z i n g a n d o i l i n g a g e n t a n d t h u s t h e g r e y f a b r i c l o se s i t s c r i m p b y m e c h a n i c a l

t e n s i o n , b e c o m i n g i n a f la t s t a te . T h e r e f o r e , i t i s n e c e s sa r y t o re s t o r e t h e c r i m p o f

t h e y a r n b y r e l a x i n g t r e a t m e n t i n w a t e r u n d e r t e n s i o n l es s c o n d i t io n . R e l a x i n g c a n

b e c a r r i e d o u t b y wa t e r , s t e a m a n d d r y h e a t a n d i t c a n b e s e e n ( F i g . 4 - 1 6 ) t h a t h o t

1 5 I

~ 1 0(D

i s.~

2 0 4 0

, /,,- , ,.,,,o

.,..,-' ~ , " ,, "

./" ~ ..

, /

,." ~ e ~ //" / dry hea t/

, /wa te r /

, /: /

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L j . . . ~ . . . . . . . . . .. ~ . .. .. . . . .. . . .. . . ~ . . ~ . . .. .. .. .. .. ~ . . . . . J .

60 80 100 120 140 160

T e m p e r a t u r e , ~

F i g u r e 4 - 1 6 . E f f e c t o f h e a t i n g m e d i u m o n r e la x a t i o n o f t e x t u r e d f a b r ic .

wa t e r i s b e t t e r t h a n s t e a m o r h o t a i r f o r o b t a i n i n g t h e f a b r i c r e l a x a t i o n t o d e v e l o p

s t r e tc h . T h e r e su l t a n t sh r i n k a g e is a b o u t 1 5 - 2 0% .

T h e t e x t u r e d f a b r i c s a r e r e l a x e d i n w a t e r a t 80 - 95 ~ i n t h e a b se n c e o f t e n s i o n

f o r 2 0 - 3 0 m i n . F o r h i g h t w i s t y a r n a n d f a b r i c a l o n g e r t i m e is r e q u i r e d . A g r a d u a l

e l e v a t i o n o f t e m p e r a t u r e i s m o r e f a v o u r a b l e t o r e l a x at i o n . A h i g h t e m p e r a t u r e

r e l a x i n g w i t h o u t t e n s i o n m a y c a u se wr i n k l i n g , so t h a t a l it tl e t e n s i o n o f th e o r d e r o f

1 -2 m g / d i s f a v o u r a b le . T h e f o r ce e x i s t in g b e t w e e n y a m s a n d i n t h e t e x t u r e d w o -v e n f a b r i c r e s t r a i n t h e r e l a x a t i o n so t h a t i t i s n e c e s sa r y t o r e d u c e t h e r e s t r a i n b y

s o m e m e c h a n i c a l i m p a c t in th e f o r m o f b e n d i n g , p r e s s i n g , v i b r a t in g a n d r u b b i n g

a c t i o n t h a t c a n b e u t il is e d b y m a k i n g u s e o f v a r io u s m a c h i n e s .

S p i n f i n i s h e s o f t e x t u r e d p o l y e s t e r y a r n s a n d k n i t te d f a b ri c n o r m a l l y c o n t a i n

o i l in g a g e n t o f s e l f- e m u l s i f i e d t y p e , a n d c a n t h e r e f o re b e r e a d i l y r e m o v e d b y r i n s -

i n g a t 5 0 - 60~ wi t h o u t a n y a d d i t i o n o f d e t e r g e n t . Sp i n fi n i sh e s t h a t d o n o t c o n t a i n

e m u l s i f y i n g a g e n t a re r e m o v e d b y w a s h i n g w i t h 1 -2 g/1 a c o m b i n a t i o n o f n o n - i o n i c

a n d a n i o n i c d e t e r g e n t a t 6 0 -7 0 ~ T h e t e m p e r a t u r e o f t h e b a t h s h o u l d n o t b e r a is e d

m o r e t h a n 2 ~ t o a v o i d p r o d u c t i o n c r e as e s .



Scour ing 125

I n mos t c a s e s s c our i ng i s c a r r i e d ou t i n c on j unc t i on w i t h t he r e la x i ng p roc e s s on

a t e ns i on l e s s m a c h i ne . I n pa dd l e s c our i ng , c i r c u l a r kn i t t e d ny l on f a b r i c s o r ga r -

m e n t s a r e l o o s e l y p a c k e d i n t o p o l y e s t e r m e s h b a g s a n d s c o u r e d / r e l a x e d i n o v e r -

he a d o r s i de -pa dd l e m a c h i n e s u s i ng 1 g /1 non- i on i c o r a n i on i c de t e rge n t , 0 . 5 g/1

s od i u m he x a m e t a ph os p ha t e a nd 1 g /1 s o l ve n t s c our i ng a ge n t a t 6 0~ fo r 30 mi n .

The l i quor i s c oo l e d , f a b r i c i n r i n s e d , hydroe x t r a c t e d a nd d r i e d w i t hou t t e ns i on a t

60-80~

T h e g o o d s m a y b e s o l v e n t s c o u r e d i n r o t a ry d r u m m a c h i n e , r e s t ri c t in g t h e l o a d

t o 5 0 % o f t h e m a c h i n e m a x i m u m c a p a c i ty a n d t h e c e n t ri f u g i n g t i m e t o 1 m i n t o

a vo i d t he fo rma t i on o f p r e s s u re c r e a s e s . W a rp kn i t t e d f a b r i c s a r e , i n ge ne ra l , m ore

s t a b le t o t e ns i on t ha n w e f t kn i t t e d f a b r i c s .

4 . 1 4 S c o u r i n g o f B l e n d e d F i b r e F a b r i c s

T h e w i d e r a n g e o f n a t u r a l a n d m a n - m a d e f ib r e s p r o v i d e s m a n y c o m b i n a t io n s t o

c r e a t e ne w e f f e c t s w i t h de s i r a b l e p rope r t i e s. S t r e ng t h , w e a r i b i l i ty a nd c r e a s e r e-

c ove ry a r e t he ma i n p rope r t i e s r e s pons i b l e fo r s yn t he t i c f i b r e s be c omi ng e s t a b -

l i s he d fo r b l e nd s w i t h c o t ton , v i s c os e a nd w oo l . The a c ry l i c s a r e a l s o i n m uc h

de ma nd fo r s uc h b l e nds , w h i l e po l ya mi de f i b r e s a nd t r i a c e t a t e s a r e o f s e c onda ryi mpor t a nc e .

4 .1 4 .1 S c o u r i n g o f p o l y e s te r / c o t t o n b l e n d s

S c o u r i n g i s m a i n l y d e s i g n e d t o r e m o v e t h e n a t u r a l o i l s a n d w a x e s f r o m t h e

c o t to n p o r t i o n a n d t h e f in i s h o il s w h i c h m a n u f a c t u r e r a d d t o p o l y e s t e r f ib r e s w h e n

e x t rude d . B l e n ds o f po l ye s t e r / c o t t on c a n be s c oure d w i t h a l ka l ine s c ou r i ng a ge n t s

a s pe r c ond i t i ons s how n i n Ta b l e 4 . 16 . T r i s od i um p hos ph a t e c a n a l s o be us e d a s a n

T A B L E 4 .1 6

A l k a l i n e S c o u r i n g C o n d i t io n s f o r P o l y e s t e r /C o t t o n B l e n d s

E q u i p m e n t S c o u r i n g a g e n t a n d c o n d i t io n s

J i gge r

J i gge r

W i n c h

P a d - s t e a m

Cau s t i c soda (3%) a t 70~ for 90 m in or a t 100~

for 15 min .

So da-a sh (5-1 0 g / l ) and de te rge nt (2-5 g / l ) a t boi l ,

or NaOH (2-5 g / l ) and de te rgent (2-5 g / l ) a t 75~

N aO H (1-2 g / l ) or NazCO 3 (2-5 g / l ) a t 75~

S od a -a s h ( 5 -10 g / l) a nd de t e rge n t ( 2 -5 g / l ), 10 0 %

pi c k -up , s t e a m i ng a t 100 ~ fo r 30 -6 0 mi n .



1 2 6 Sc o u r i n g

a l k a li . T h e u se o f e m u l s i fi a b l e so l v e n t s c o u r in g a g e n t s a r e u se fu l . C o m b i n e d s c o u r -

i n g a n d b l e a c h i n g p r o c e s s u s i n g a l k a l i n e h y d r o g e n p e r o x i d e is a ls o p r e f e r r e d f o rt h e r e a so n o f e c o n o m y . F a b r i c s c o n t a i n i n g p o l y e s t e r f ib r e sh o u l d n o t b e k i e r - b o i le d .

I n s u c h b l e n d s , m i l d e r c o n d i t i o n s o f a lk a l i n it y a n d t e m p e r a t u r e a r e u s e d t o a v o i d

d e t r i m e n t a l e f f e c t s o n t h e p o l y e s t e r p o r t i o n .

4 . 1 4 .2 S c o u r i n g o f p o l y e s te r / w o o l b l e n d s

P o l y e s t e r /w o o l b l e n d s a re v e r y p o p u l a r, t h e m o s t c o m m o n b l e n d r a t i o s a r e 5 5 :4 5

a n d 7 0 : 3 0 p o l y e s t e r : w o o l . P o l y e s t e r r ic h b l e n d s a r e n o r m a l l y c o n s t r u c t e d f r o m a

t e x t u r i s e d p o l y e s t e r f ib r e w a r p a n d 5 5 :4 5 p o l y e s t e r : w o o l w e f t y a m s . T h e 2 0 : 8 0

p o l y e s t e r / w o o l i s w o v e n f r o m 5 5 :4 5 w a r p a n d a p u r e w e f t y a m . W o r s t e d p o l y e s -

t e r / w o o l b l e n d y a m s m a y c o n t a i n 2 .5 - 3 % s o l v e n t e x tr a c t a b le o il , c o m p a r e d w i t h

3 .5 - 5 % f o r s i m i l a r a l l wo o l y a m s . T h e o i l s h a v e m u c h g r e a t e r a ff i n i ty f o r p o l y e s -

t e r fi b r e t h a n wo o l a n d a f t e r n o r m a l p i e c e s c o u r i n g , t h e b l e n d s c o n t a i n r e s i d u a l o i l

c o n t e n t o f 0 . 6 - 1 . 2% c o m p a r e d w i t h 0 .3 % f o r w o o l . O x i d a t i o n o f c o m b i n g o i l is

i n f l u e n c e d b y e x p o s u r e t o l ig h t w h i c h s h o u l d b e a v o i d e d b e f o r e s c o u r i n g . A d d i -

t i o n o f su r f a c t a n t t o c o m b i n g o i l i m p r o v e s t h e s c o u r a b i l i t y o f t h e b l e n d f a b r i c [ 75 ] .

T h e o b j e c t o f s c o u r i n g p o l y e s t e r / w o o l b l e n d e d f a br ic i s n o t o n ly t o r e m o v e s p inf in i shes , l u br i ca t ing o i l s , s i ze s and con tam ina t ion o f a l l t ypes , i t a l so he lps in fabr i c

r e l a x a t i o n a n d p a r ti n g th e n e c e s s a r y c o m p a c t n e s s . B l e n d e d f a b ri c s m a y a l s o b e

p r e s s e d a n d f l a tt e n e d b y a n y o f t h e u s u a l m e t h o d s e m p l o y e d w i t h a l l - w o o l c l o t h

b e f o r e s c o u r i n g .

S c o u r i n g c a n b e c a r r ie d o u t e i t h er i n r o p e f o r m i n D o l l y w a s h i n g m a c h i n e f o r

w o o l r i c h b l e n d s o r o p e n w i d t h f o r m f o r p o l y e s t e r r ic h b le n d s . T h e s p i n f in i s h e s

a r e r e m o v e d b y 0 . 5 - 1 % n o n - i o n i c a l k y l p h e n o l p o l y g l y c o l e t h e r t y p e o f d e t e rg e n t

a n d 0 .2 5 - 0 .5 m l /1 N H 3 ( 2 5 % ) o r 0 .2 - 0 .4 g/1 so d a - a s h a t p H 8 t o 9 f o r 2 0 - 3 0 r a i n a t

4 0 - 5 0~ Sy n t h e t i c d e t e r g e n t so l u ti o n a t p H 5 t o 6 c a n b e u se d to m i n i m i se d e g r a -

d a t io n . T h e p r e s e n c e o f m a n - m a d e f ib r e in a b l e n d w i th w o o l ( g r e a t e r t h a n 2 0 % )

m a y i n h i b i t m i l l in g . I n g e n e r a l , t h e g r e a t e r t h e p e r c e n t a g e o f wo o l i n t h e c l o t h t h e

g r e a t e r is t h e sh r in k a g e . T h e f a b r i c is f i n a l ly w a sh e d - o f f at 3 5 - 4 0~ f o r 4 5 ra i n ,

a n d t h e n c o o l e d g r a d u a l l y . A t y p i c a l p r o c e d u r e f o r a so f t f i n ish f o r p o l y e s t e r /w o o l

k n i t t e d g o o d s i s t o s c o u r i n t u b u l a r f o r m ( f a c e in s i d e ) a t 3 0 - 3 5 ~ f o r 2 5 m i n i n 4 o

T w N a 2 C O 3 ( 1 . 9 % s o l u ti o n ) a n d 4 % s o a p ( o . w .f .) . A f t e r w a s h i n g - o f f i n w a t e r a t35~ fo r 15 m in , t he fabr i c is d r i ed on e i the r tubu la r d r i e r o r s t en te r , is c ro pp ed



Sc o u r i n g 1 2 7

c l o se l y o n t h e f a c e s i d e , o p e n s t e a m e d f o r f u l l r e l a x a t i o n a n d f i n a l l y d e c a t i s e d .

I n c a se o f so l v e n t s c o u r i n g i t i s c l a i m e d t h a t t r i c h l o r o e t h y l e n e a t t h e b o i l p r o -

v i d e s a s a t i s f a c to r y m e t h o d i n a c o n t i n u o u s o p e n w i d t h p l a n t o f sp e c i a l d e s ig n .

4 . 1 4 .3 S c o u r i n g o f p o l y e s t e r / a c r y l i c b l e n d s

Sc o u r i n g o f p o l y e s t e r / a c r y l i c f i b r e b l e n d e d f a b r i c s c a n b e c a r r i e d o u t in e i t h e r a

w e a k l y a c i d o r a l k a l in e b a t h u s i n g a c o m b i n a t i o n o f 0 .5 - 1 g /1 n o n - i o n i c a n d a n i o n i c

d e t e r g e n t s . T h e p H o f th e b a t h i s a d j u s t e d t o 5 - 6 w i t h a c e t i c a c i d o r 8- 7 w i t h a m m o -

n i a o r so d a - a sh a n d th e t r e a t m e n t is d o n e f o r 2 0 - 3 0 r a i n at 60~ ( f o r a c i d i c p H ) a n d

4 0 - 5 0 ~ ( fo r a l k a l in e p H ) . T h e a m o u n t o f d e t e r g e n t u s e d d e p e n d o n t h e d e g r e e o f

so i l in g . A f t e r wa sh i n g , r i n s i n g p r o c e e d s u n t i l t h e c l o t h i s f r e e o f a l k a l i. I t i s a n

a d v a n t a g e t o so u r t h e l a s t r i n s i n g w i t h a li tt l e a c e ti c a c i d .

4 . 1 4 . 4 S c o u r i n g o f a c r y l i c / w o o l b l e n d s

W o o l / a c r y l i c f ib r e b l e n d y a r n s a r e p r e p a r e d o n th e w o o l l e n o r w o r s t e d s y s t e m s

o f s p in n i n g . G e n e r a l l y , f a t t y a ci d ty p e o f l u b r ic a n t s a p p l i e d i n w o o l l e n p r o c e s s i n g

sh o u l d b e a v o i d e d t o p r e v e n t d i s c o l o u r a t i o n o f t h e a c r y l i c fi b re s . H i g h b u l k a c r y l i c

f ib r e s a re a l so u s e d i n t h e w o o l i n d u s tr y . B l e n d y a m s c o n t a i n i n g u n r e l a x e d h i g h -

b u l k a c r y l i c f i br e s h o u l d b e c o m p l e t e l y re l a x e d b e f o r e b e i n g d y e d , e i th e r b y s t e a m -i n g i n a n a u t o c l a v e a t 1 07~ f o r 1 0 m i n a f te r p r e l i m i n a r y e v a c u t i o n o f t h e s t e a m e r ,

o r b y i m m e r s i o n i n b o i l i n g w a t e r f o r 5 m i n .

F o r w o r s t e d y a m s , s c o u r i n g c a n b e c o n d u c t e d a t a m a x i m u m t e m p e r a t u r e o f

60~ f o r 3 0 m i n w i t h 1 g /1 n o n - i o n i c d e t e r g e n t a n d 0 .5 m l /1 a c e t i c a c i d ( 80% ) .

W o o l l e n s p u n y a m s l u b r i c a t e d w i t h o le i n e ar e s c o u r e d a t 3 0 ~ w i t h s o a p o r s y n -

t h e ti c d e t e r g e n t a n d s o d i u m c a r b o n a t e . T h e a d d i t i o n o f s o l v e n t i s s o m e t i m e s a d -

v a n t a g e o u s f o r t h e r e m o v a l o f o il s. T a p e s c o u r i n g m a c h i n e s a r e g e n e r a l l y u s e d f or

t h e s c o u r i n g o f h a n k s .

A c r y l i c / w o o l b l e n d e d f i b r e f a b r i c s m a y b e p r e p a r e d a c c o r d i n g t o e s t a b l i s h e d

p r a c t i c e f o r wo o l , e x c e p t t h a t p r e c a u t i o n s a r e t a k e n t o a l l o w f o r t h e t h e r m o p l a s t i c

p r o p e r t i e s f o r th e a c r y l i c f ib r e s . R e l a x a t i o n i s d o n e t o r e m o v e t h e i n h e r e n t s t ra i n .

W o r s t e d f a b r ic s a r e c r a b b e d a n d t h e n s c o u r e d i n e i th e r a D o l l y a t t e m p e r a t u r e n o t

e x c e e d i n g 4 0 ~ o r i n w i n c h .

4 . 1 4. 5 S c o u r i n g o f a c r y l i c / c e ll u l o s ic s b l e n d s

B l e n d e d y a r n s o f a c r y li c / c e ll u l o s i c f ib r e s a re p r e p a r e d o n t h e w o o l l e n s y s t e m .Y a m s p r e p a r e d i n t h e c o t t o n s y s t e m o f s p i n n i n g m a y b e s c o u r e d a t 6 0~ ( 30 ~ f o r



128 Scour ing

unre l a xe d bu l k e d ya m s ) fo r 30 m i n i n a l i quor c on t a i n i ng 1 g /1 non- i on i c de t e rge n t

a nd 0 .5 ml/1 a ce t ic a c i d ( 8 0 % ) . Fa b r i c s s ho u l d be de s i z e d a nd s c oure d t o r e m ove

s i z e s, s p i nn i ng a s s i s t a n t s a nd o t he r i mpur i t i e s . S c our i ng c a n be c a r r i e d ou t w i t h 1

g /1 non - i on i c de t e rge n t , 1 g /1 t r i s od i um pho s pha t e a t 6 0~ fo r 30 mi n fo l l ow e d by

r i ns i ng w e l l w i t h s u f f i c ie n t w a t e r .

4 . 1 4. 6 S c o u r i n g o f a c e ta t e / w o o l b l e n d s

D i a c e t a t e a nd t ri a c e t a te a r e bo t h us e d i n b l e nds w i t h w oo l . S c ou r i ng a nd mi l l -

i n g c a n b e c o n d u c t e d w i t h th e m i n i m u m q u a n t it y o f a lk a li a t t e m p e r a t u r e s n o t e x -

c e e d i n g 50 ~ a nd c a r e s hou l d be t a ke n to a vo i d e xc e s s i ve m e c ha n i c a l f r i c ti on on

t he f a b r i c. Fa b r i c s ma d e f rom t r ia c e t a t e / w oo l b l e nd s s hou l d be g i ve n a c r a bb i ng

t r e a t m e n t b e f o r e d y e i n g .

4 . 1 4. 7 S c o u r i n g o f b l e n d s c o n t a i n i n g v is c o s e

S t a n d a r d v i s c o s e a n d p o l y n o s i c r a y o n s a r e b l e n d e d w i t h c o t t o n f o r i m p r o v e d

phy s i c o -c h e m i c a l p rope r t i e s o f t he b l e nd e d f a b r ic . The i nc r e a s e in t e ns i le s t r e ng t h

b r o u g h t a b o u t b y b l e n d i n g w o o l w i t h v i sc o s e is w e l l - k n o w n . F a b r i c s c o n ta i n i n g

a rou nd 6 5 % t r i a c e ta t e w i t h v i s c os e ma y be g i ve n du ra b l e p l e a ts . B u l ke d o r t e x -

t u r e d ny l on i s s om e t i me s us e d w i t h v i s c os e r a yon fo r f a b r ic s . Ta b l e 4 . 17 s how s

T A B L E 4 . 1 7

S c o u r i n g C o n d i t io n s f o r B l e n d s C o n t a i n i n g V i s c o s e

B l e n d Tre a t me n t c ond i t i ons

V i s c os e / C o t t on

V i s c os e / W ool

V i s c os e / A c e t a t e

V i s c os e / A c ry l i c

V i s c o s e / N y l o n

V i s c o s e / R e g e n e r a t e d

pro t e i n

0 . 1% s oa p ; 0 . 1% N a O H ; 1 h a t bo i l .

3 % n o n - io n i c d e t e r g e n t ; 1 m l / 1 N H 3 ( 0 . 8 8 sp. gr.);

15-20 min a t 40-45~

0 . 2% s oa p , 0 . 2% a mmoni um hydrox i de ( s p . g r .0 . 88 ) ; 30 mi n a t 9 0~ Te m pe ra t u r e s hou l d no t

e xc e e d fo r b r i gh t a c e t a te .

0 . 25% s yn t he t i c de t e rge n t ; 0 . 5% s od i um a c e t a t e

or ace t i c ac id , ad jus ted to pH 5 .5-6 ; 30 min a t

90~

2-5% ( o . w . f . ) s oa p o r s yn t he t i c de t e rge n t ; 2 -5%

t r i s od i um pho s pha t e ; 30 mi n a t 40 -7 0~

Solut ion i s s ame as for v i scose /ac ry l i c b lend ; 30

min a t 50~



Scour ing 129

som e r e p r e se n ta t ive sc our ing t r e a tm e n t s tha t a re su i t a b le f o r spe c i fi c b l e nds c on-

t a in ing v i sc ose f ib re s bu t i n p r a c ti c e the p r e c i se c ond i t ions va r y a l so w i th the p r o -c e dur e a nd m a c h ine r i e s u se d .

4 . 1 4 .8 S c o u r i n g o f p o l y e s t e r / s i l k b l e n d s

B le nd s o f na tu r a l s i lk a nd po lye s t e r f ib r e s ( 35 :6 5) a r e som e t im e s use d f o r d r e s s

goods , b louse f a b r ic s a nd m e n ' s f a sh ion we a r . S i z ing age n t s a nd so i ls a re re m ove d

by w a sh ing wi th a m in i m um te ns ion in ope n soa pe r c on ta in ing 1 g /1 non- ion ic

d e t e r g e n t a n d 1 m l / 1 N H 3 ( 2 5 % ) at 50~

4 . 1 4 . 9 S c o u r i n g o f b l e n d s c o n t a i n i n g c a s e i n f i b r e s

Cas e in /ce l lu los ic f ibre b lende d fabr ic is f i rs t des ized und er mi ld ly ac id ic cond i-

t ions a t 60-70~ for 30-60 ra in and then sco ur ing i s ca r r ied out in a f resh ba th a t

pH 6 w i th 3-4 g/1 non - ionic de te rg ent a t 50-60~ for 30 ra in , and r insed w e l l , fi r s t

in wa r m a nd the n in c o ld wa te r.

B le nds c on ta in ing c a se in /woo l c a n be sc our e d w i th 1 g/1 non- ion ic de te r ge n t ,

1 g /1 sod ium hyd rosu lphi te and 1 ml /1 N H 3 ( sp . gr . 0 .88) for 30 ra in a t 50~ The

gr e y f a b r i c i s s c our e d in the Do l ly o r w inc h wi th m in im um m e c ha n ic a l a c t ion .

S t r ong a lka l i e s and p r o lon ge d we t p r oc e ss ing t e m pe r a tu r e s a bove 8 0 ~ a r e no ta dv i sa b le. Apa r t f r om c e r ta in l im i t a t ions in s cour ing , m o s t o the r wo o l l e n a nd wo r -

s t ed p r e pa r a t ion a nd f in i sh ing ope r a t ions c a n be c a r ri e d ou t w i thou t m a jo r c ha nge s ,

the y inc lude c a r bon i s ing , c r a bb ing , b lowing , de c a t i s ing a nd p r e s s ing .

R E F E R E N C E S

1 M. S . El l io t and D. Whi t t le s tone , J . Soc . Dyers Colour is t s , 110 (1994)266 .2 G. V. H o m u ff and H. Richte r , Fasa . u. Tex m . , 15 (1964) 165.

3 C .F . Prut ton and S. H. Mar ion , Fund am enta l Pr inc ip les of Phys ica l Chem is t ry ,

M a c m i l l i a n C o . , N e w Yor k , N . Y ., ( 1957 ) 7 8 0.

4 J . E . Ne t t l e s , Ha nd boo k o f C he m ic a l S pe c ia lt i e s, John Wi le y & S ons , Ne w

York, Chiches te r (1983) , p 384.

5 R . Freytag , Colourage , 22 (1975) 35 .

6 X. Ko w alsk i , J. , AA TC C, 10 (1978) 161.

7 D . P r i c e , " De te r ge n t s " , C he m ic a l Pub . C o . , I nc o r por a t e d , Ne w Yor k , N .Y . ,

(1952) p 63.8 E . R . T r o t m a n , D y e i n g a n d C h e m i c a l T e c h n o l o g y o f T e x t i le F i b re s , G ri ff in ,

London, England (1964) p 178 .



130 Scouring

9 A .W . Adam son, Phys ical Chem is t ry of Surfaces , In tersc ience Publi sh ing , NewYork , N . Y ., (1964 )p 371 .

10 Ob etz. Tex t i le A~ia, 4 (N ov 1973) 20.11 Andrews , Dyer , 153 (May 1975) 466.

12 R. Steele, J . Soc. Dy ers Co louris t , 110 (1994) 6.

13 M . S. El l iot and D. W hit t le s tone , J . Soc. Dye rs C olouris ts , 110 (1994) 266.14 R. Taylor, Dyer (Apr 1995) 16.

15 H .H . H ofs te l ler , Me l l iand Text i lber . , 50 (1969) 321.

16 G. Reinert , Text i lveredlung, 10 (1975) 85.

17 J . M echee ls , Text i lveredlun g, 40 (1969) 749.

18 A.J . Shipman, Text i lveredlung, 5 (1970) 523.

19 M. Sch w ierer, Australa nian Tex t i les , 1 (1) (1981) 19.

2 0 W a c h e r - C h e m i e , G e r m a n P a te n t, 1 , 2 7 5 , 5 3 1 ( 19 65 ).

21 S oc i e t a Ed i son , Germ an Pa t en t , 1 , 25 8 , 4 04 (1965).

22 Dy nam i t Nob e l , Germ an Pa t ent , 1 , 29 3 , 7 32 (1963).

23 Pi t sburg Pla te Glass , Germ an Patent, 1 ,285 , 991 (1962).

24 Pech iney , BP 1 , 120 , 239 (1965) .

25 Dow, B P 1 ,096, 866 (1965) .

2 6 D o w , B P 1 , 1 2 3 , 8 5 8 ( 19 6 7) .

27 Guta m ann, Chim ia , 23 (1969) 283.

28 Normani , Angew. Chem. , 79 (1967) 1029.29 J . Kurz , 'Die Praxis der Chem ischrein igung ' (Gem mrighe 'm : Fachbuchver lag) ,

J . Kurz (1969).30 Vo n Berg en, W. , W ool Handb ook , In tersc ience Pub. , N ew Yo rk , Vol . II , Par t

I (1969) p 22.

31 N. K. Ad am , J . Soc. Dy ers Colou ris ts , 53 (1897) 121.32 K. Sw ans to m and R. C . Palme r , J . Text i le Ins t. , 52 (1951) 675.

33 R. P. Harper , W IR A Repo r t , 138 (1971) 1 .

34 C. A. Ande rson , Text i le Res. J ., 53 (12) (1983) 741.35 T . E . T hom pson , The S cour ing o f Raw W ool in Theory and Prac ti ce , Tex t i le

Manf . Monograph No. 2 , 1940.

36 J . I . Sinclair , Proc. 1st . Int . W oo l Text . Res. Con f. , Vol E (1955) 3 47.

37 M. Lipson and G. W. Wal l s , Proc . 2nd. In t . Wool Text . Res . Conf . (1960)

395.

38 J . To w ne nd , J. Te xt i le Inst. , 27 (1936) 219.

39 T. Sha w and J. Lew is, Te xt i le Progres s , 4 (3) (1972) 38.

40 J . B. Spea km an, J . Soc. Dy ers Colou ris ts , 52 (1936) 335.

41 C. S. W he w ell an d H. A. Tu rner, J . Te xt i le Inst. , 42 (1951) 133.

42 I . M . Bo na, Int . Te xt i le Bull . , Dy g/Ptg. /Fing . , 1 (1994) 38.

43 J . Kno t t , P . Za narol i and A. M akro , Proc . 7 th W ool Text . Res . Con f . , To kyo ,

Vol V, 1985, pp 99- 107.



Scouring 131

44 T . E . M ozes , SW AT RI Spl . Pub . , Apr i l 1986.

45 H. Z ahn , J . Soc. Dy ers Colou rists , 76 (1960) 226.46 W u. Z hao an d M. T. Pail thorp e, Texti le Res. J. , 57 (1987) 39.47 B alcken berg and Breuers , M il l iand Tex t i lber ., 63 (1982) 515 .

48 M. S. Ed en bo rou gh and M. Chaikin , J . Tex ti le Inst . , 70 (1979) 62.

49 W u. Z hao and N. A. G. Johnson , Tex t i le Res . J ., (1986) 741 .

50 W u. Z hao and M. T. Pail thorp e, Texti le Res. J ., (Sept 1987) 523.

51 K . H a r t k o f f a n d H . K . R o u e t t e , S c h r i f t e n r e i h e d e s D e u t s c h e n ,W ol l fo rschu nges in is tu tes , 1986, No .99 , pp 441-446.

52 M. L iebesk ind , H. H~cker , C. W and rey and A. G. J~/ger, FE M S M icroboi l .Lett. , 71 (1990) 325.

53 R. S . Z uko w ska and A. Z akrzew ski , Po l i sh Pa ten t , 147 ,49 8.54 J. Park, J . Soc. D yer C olourists , 87 (1971) 111.

55 A. S. B ianc hi and G. M. Co lonna , M ell ian d Texti lber . , 1 (1992) 68.

56 E . Wagner , Die tex t i len Rohstof fe , 6 , Auf lage (1981) , Dr . Spohr Ver lag /Deu tscher Fachver lag .

57 J. Gallois , Tien tex, 9 (1966) 613.

58 M. S. Du nn, M. N. C am in, J. S. Ro dland , S. Sh ank m an and S. C. Go ldberg , J.Biol . Chem., 155 (1944) 591.

59 S . Brez ez insk i and G. M al inow ska , M el l iand Tex t i lber . , (Eng . Ed . ) 70 (1984)40.

60 P. P. Vik torv and Z. S. Bloc h, Text . Proun. , 11 (1933) 43.61 S . Brez ez insk i and G. M ahino wh a, Brbeg l W OR K, 43 (4) (1989) 160.

62 F. Schm itz , F~i 'ben und Au sr~gten von S eide, TPI 38 (1983) 6 and 575.

63 Y. Ka w ah ara and S. N aka jim a, J . Ser ic . Sci. , Japan, 61 (1992) 460.64 M. L. Gu lrajani , Rev. Prog. Color . , 22 (1992) 79.65 T .N . Son w alkar and J . Prabhu , Colourage , 39 (7) (1992) 37.66 M. An s to e tz , D ip lo m ar b e i t F ach h o ch sch u le N ied e r r h e in Mo n ch en g lad b ach

(1983) .67 R. A. Be m aro ld, Te xti le Inf. Dig. , 9 (2) (1981) 19.

68 P. C. Dasg upta , K. Sen and S. K. Sen, Ce llul . Ch em . Tech. , 10 (1976) 285.

69 C. G. Jarm an, A. J. C ann ing and S. M yklu k, Trop. Sci . , 20 (2) (1978) 91.

70 B. Lunik, Texti le Q . , 4 (1954) 42.

71 H. Jefferson, Texti le Color . , 49 (1927) 747.

72 W . M arsh al , J. Soc. Dy ers Colo urists , 40 (1924) 10.

73 D. W ang , J. Tex ti les, 18 (2) (1983) 25 (in Ch inese) .

74 Y. Zh eng , Ze . Z hang and Z e . Luo , Tex t i le Res . J ., 58 (11) ( N ov 1988) 663 .

75 R. S. Heart ly and R. F. Elseworth , Proceedings, J . Texti le Inst . , 49 (1958)554.



Chapter 5

S C O U R I N G M A C H I N E R I E S

5 . 1 I n t r o d u c t i o nSco u r in g can b e ca r r i ed o u t in b a t ch , s em ico n t in u o u s an d co n t in u o u s p r o ces s es .

T h e m a c h i n i s a t i o n o f t h e p o s t- k i e r s c o u r in g s t a g es h a d b e e n p r o g r e s s i v e l y d e v e l -

o p ed f r o m th e ea r ly 1 93 0 s. T h e n o n - co n t in u o u s p r o ce s s co n s i s t s e s s en t i a l l y o f

c i r cu l a t i n g h o t a lk a li l i q u o r th r o u g h th e c lo th in a v ess e l ca l led k i e r. T h e co n t in u -

o u s s co u r in g an d b l eac h in g i n t h e J -Bo x h as b een e s t ab l i s h ed a f t e r 1 960. T h e co n -

t i n u o u s p r o ce s s i s b as ed o n t h e im p r eg n a t io n o f th e f ab r ic i n an a lk a li s o lu t i o n

f o l l o w e d b y s t eam ag e in g s t ag e , t h e f ab ri c b e in g e i t h e r in r o p e f o r m o r o p en w id th

f o r m . Kie r s h av e g iv en w ay to J - Bo x es an d J - Bo x es a r e d i s ca r d ed i n f av o u r o f

o p en w id th s co u r in g w h ich r eq u i r e s o n ly 2 - 1 5 m in h av in g v e r y h ig h p r o d u c t io n . In

co m p ar i s o n k i e r s t ak e 6 -1 2 h d ep e n d in g u p o n th e am o u n t o f im p u r i t i e s .

5 .2 B a t c h T y p e S c o u r in g M a c h i n e s ( R o p e F o r m )

5 . 2 . 1 L o w p r e s s u r e k i e r

Va r io u s d es ig n s o f k i e r s a r e av a i l ab l e [ 1 ,2 ] . Lo w p r es s u r e o r o p en k i e r s a r e

g en e r a l l y m ad e w i th a h in g ed l i d , an d t h e s co u r in g l iq u o r s a r e c i r cu l a ted b y i n j ec to r

s y s t em o r b y t h e p r o v i s io n o f an ex t e r n a l m u l t i tu b u l a r h ea t e r an d p u m p (F ig . 5 - 1 ).

~ . r - , r m 0 , ~ 1 7 6 1 7 6 o

i i i i l i

Figu re 5 -1 . A typ ica l low pre ssure k ier .

T h e s t eam in j ec to r l o ca t ed a t th e cen t r e o f t h e k i e r p e r m i t s t h e h ea t i n g o f t h e b a th



S c o u r i n g M a c h i n e r i e s 1 33

a n d t h e l i q u o r i s c i r c u l a t e d f r o m b o t t o m t o t o p b e f o r e s p r a y i n g i t o n t h e f i b r e .

O p e n k i e r s a r e m a i n l y u s e d f o r li n e n , y a r n a n d c l o t h s m a d e o f l o o s e l y w o v e n g o o d s

a n d k n i t t e d m a t e r i a l s e t c . w h i c h w i l l n o t s t a n d h i g h p r e s s u r e b o i l i n g i n a l k a l i n e

s o l u ti o n s . T h i s t y p e o f k i e r s a re a l so p r e f e rr e d f o r c o l o u r e d w o v e n g o o d s w h i c h

o p e r a t e s a t a t m o s p h e r i c p r e s s u r e b e l o w 1 00 ~ T h e m a i n d i s a d v a n t a g e o f t h is t y p e

o f m a c h i n e i s t h e d i lu t i o n o f th e b a t h b y c o n d e n s e d s t e a m o n a c c o u n t o f d i re c t

s t e a m h e a t i n g s y s t e m .

5 .2 .2 H i g h p r e s s u r e k i e r

T h e p r o t o t y p e o f m o d e m h i g h p r e s su r e k e i r (F ig . 5 - 2 ) w i t h m u l t it u b u l a r h e a te r

i s o f t e n r e f e r r e d t o a s W a l s h ' s k i e r a nd c ons i de re d t o be t he be s t . A 2 t ons c a p a c i t y

F i g u r e 5 - 2 . H i g h p r e s s u r e v e r t i c a l k i e r w i t h m u l t i t u b u l a r h e a t e r.

k i e r is m o s t c o m m o n w h i c h i s a b o u t 9' h i g h a n d 6 . 5' in d i a m e t e r a n d m o u n t e d o nR . C .C . c o l u m n s . T h e k i e r is g e n e r al ly m a d e f or a m a x i m u m l ik e l y w o r k i n g p r es -



134 S c o u r i n g M a c h i n e r i e s

su r e 4 0 l b / i n 2 ( 2 .81 2 k g / c m 2) a t 1 4 1 ~ a n d i s c o m p o se d o f m i l d s t e el p l a t e s w i t h

c o u n t e r s u n k r i v e t h e a d s i n s i d e to g i v e a sm o o t h su r f a c e . T h e k i e r is p r o v i d e d w i t hv a r i o u s m o u n t i n g s a n d a c c e s s o r ie s s u c h a s p r e s s u r e g a u g e , s a f e ty v a l v e, b l o w o f f

v a l v e f o r a ir a n d s t e a m , s t e a m t r a p , l i q u o r l e v e l i n d i c a t o r , d r a i n c o c k e t c .

T h e g o o d s i n r o p e f o r m a r e p il e d e i t h e r m a n n u a l l y o r b y m e c h a n i c a l p l a i t i n g o n

t h e p e r f o r a t e d f a l s e b o t t o m . T h e c l o t h c a n b e s a t u r a t e d w i t h a l k a l i n e so l u t i o n s

c o n t a i n i n g c a u s t i c so d a ( 2 t o 3 % ) , so d i u m s i l i c a t e ( 0 .75 t o 1 % ) , so d i u m c a r b o n a t e

( 0.5 to 1 % ) a n d w e t t i n g a g e n t ( 0 .1 % ) d u r i n g p i l in g . Su f f i c i e n t s c o u r i n g l i q u o r is

t h e n a d m i t t e d t o t h e k ie r f r o m b e l o w t o s w e e p o u t e n t r a p p e d a ir f r o m t h e g o o d s t o

a v o i d t h e f o r m a t i o n o f o x y c e l l u l o se . T h e l i d i s t h e n c l o se d b u t th e a i r v a l v e i s k e p t

o p e n . S t e a m i s t u r n e d o n a n d li q u o r is c ir c u l a te d b y c e n t r if u g a l p u m p ( C ) c o u p l e d

t o a n e l e c t r ic m o t o r . H i g h p r e s su r e k i e r o p e r a t e s a t a b o u t 1 3 0~ ( 2 .1 09 k g / c m 2) f o r

a b o u t 8 t o 1 0 h w i t h a li q u o r r a ti o b e t w e e n 5 :1 t o 6 :1 . A f t e r s c o u r i n g t h e d r a i n c o c k

i s o p e n e d a t r e d u c e d p r e s su r e (5 t o 6 lb / i n 2) a n d e q u i v a l e n t a m o u n t o f h o t wa t e r i s

a d m i t t e d f r o m t h e t op . A f t e r ci r c u l a ti n g c o ld w a t e r th e g o o d s a r e r e m o v e d a n d

w a s h e d i n a r o p e w a s h i n g m a c h i n e . T h e l iq u o r is w i t h d r a w n f r o m t h e b o t t o m o f

t h e k i e r ( A ) a n d f o r c e d t h r o u g h t h e h e a t e r ( B ) a n d sp r e a d o v e r t h e to p o f t h e lo a d b yt h e d i s t r i b u t o r ( D ).

F a b r i c s wh i c h a r e t o b e so l d i n wh i t e s t a t e a r e g i v e n t wo b o i l s a n d t h e f a b r i c

i n t e n d e d f o r p r i n t in g , s i n g l e b o i l i s su f f ic i e n t. R e c e n t l y , t h e k i e r h a s b e e n so m o d i -

f i e d a s t o r e d u c e t h e t im e f o r p r e s su r e k i e r i n g o r e v e n p e r o x i d e b l e a c h i n g . T h i s i s

a c h i e v e d b y u s i n g s a t u r a t o r s , a u t o p i l e r s a n d r e so r t i n g t o s t e a m i n g a s in t h e c a se o f

J - B o x r a n g e .

5 .2 .3 J a f f e r s o n - W a l k e r ' s k i e r

K i e r o f t h is t y p e ( F ig . 5 - 3 ) i s a l so a v e r ti c a l k i e r b u t u t il i se s a v a c u u m sy s t e m f o r

F i g u r e 5 - 3 . T h e J e f f e r so n - W a l k e r k i e r .



S c o u r i n g M a c h i n e r i e s 135

c i r c u l a t i on o f t he k i e r li quor . I n th i s s ys t e m, t he r e i s a s ma l l s ubs i d i a ry r e c e i ve r k i e r

b e t w e e n t h e a c t u a l k ie r a n d s u p p l y p ip e . A b o u t o n e - f i f th o f t h e l iq u o r i n th e k i e r i sw i t h d r a w n i n t o t h e r e c e i v e r k i e r a n d t h is c r e a te s a p a r t ia l v a c u u m , d r a w i n g f a b r ic

t o g e t h e r . T h e k i e r l iq u o r i s p e r i o d i c a l l y w i t h d r a w n , h e a t e d a n d t h e n r e t u r n e d t o th e

k i e r . Th e e n t i r e l i quor i s c i r c u l a t e d e ve ry 10 -12 m i n .

5 . 2 . 4 G e b a u e r k i e r

Th e un i t ( F i g . 5 -4 ) c ons i s ts o f tw o c onc e n t r i c ve s s e l s one i n s i de t he o t he r w i t h a

F i gu re 5 -4 . Th e G e b a ue r ' s k i e r.

p e r f o r a t e d i n n e r j a c k e t . T h e h e a t e d s c o u r i n g l i q u o r is in j e c t e d a t t h e to p b e t w e e n

t he t w o c onc e n t r i c w a l l s . In t h is s ys t e m t he f l ow o f li quor i s r a d i a l i n s t e a d o f ve r t i-

c a l c i r c u l a t i on a nd t hus the c l o t h m ore o r le s s fl oa ts . The p r e s s u re d i f f e r e nc e be -

t w e e n t o p a n d b o t t o m i s e l i m i n a t e d .

5 .3 B a t c h T y p e S c o u r in g M a c h i n e ( O p e n W i d th F o r m )

H e a v y f a b r ic s l ik e d r il ls , c o r d e d f a b r ic s a n d o t h e r w e a v e s s h o w r o p e m a r k s a n d

c r e a s e s i f t h e y a r e s c o u r e d i n r o p e f o r m . S u c h f a b r ic s a r e sc o u r e d i n o p e n w i d t h

f o r m .

5 . 3 . 1 M a t h e r a n d P l a t t ' s h o r i z o n t a l k i e r

M a t h e r a n d P l a t t h o r i z o n t a l k i e r ( F ig . 5 - 5 ) c o n s i s ts o f a h o r i z o n t a l s h e ll w i t h

u s u a l m o u n t i n g s a n d a c c e s s o ri e s . F o u r w a g o n s a r e su p p l i e d w i t h t h e m a c h i n e , tw o

a re f i l le d w i t h f a b r i c o u t s i de t he k i e r w h i l s t t he o t he r t w o a r e in p roc e s s i n t he k i e r .

T h e g o o d s s a t u r a t e d w i t h s c o u r i n g s o l u t io n a r e r u n o n t h e i ro n r a i ls s e c u r e d t o th e

k i e r b o t t o m a n d t h e n t h e f ro n t d o o r is c lo s e d a n d f a s t e n ed . T h e h o t a l k a li n e l i q u o r

i s t h e n c i r c u l a t e d f o r 6- 8 h u n d e r r e q u i r e d p r e s s u r e a n d t e m p e r a t u r e d e p e n d i n g o n

t h e ty p e o f g o o d s . T h e b a t h i s h e a t e d b y a n e x t e rn a l m u l t i tu b u l a r h e a t e r a n d t h e



136 S c o u r i n g M a c h i n e r i es

F i g u r e 5 - 5 . H o r i z o n t a l k i e r ( M o t h e r & P l a t t) .

l i q u o r is sp r a y e d o n t h e f a b r ic i n t h e w a g o n b y u m b r e l l a sp r a y i n g d e v i c e . A f t e r

b o i l i n g i s o v e r t h e g o o d s a r e w a sh e d o n c e o r t w i c e i n t h e k i e r . T h e d i r e c t i o n o f

c i r c u l a t io n o f li q u o r c a n be r e v e r s e d d u r i n g th e b o i li n g o r w a s h i n g p r o c e s s e s . T h e

m a c h i n e c a n a l so b e u s e d f o r l o o s e c o tt o n a n d y a m .

5 . 3 . 2 J a c k s o n k i e r

F a b r i c s a r e s e c u r e d i n o p e n w i d t h f o r m i n t h e J a c k s o n k i e r a s s h o w n i n

F i g s . 5 - 6 ( a ) a n d 5 - 6 ( b ). I t c o n s i s t s o f a h o r i z o n t a l sh e l l a n d a c a r r a i g e w h i c h su p -

F i g u r e 5 - 6 ( a ) . J a c k so n k i e r . F i g u r e 5 - 6 ( b ) . I m p r e g n a t i n g d e v i c e .

p o r t s t h r e e r o l l e r s . T h e t w o o u t e r b a t c h r o l l e r s r o t a te i n t h e f i x e d b e a r i n g s a t e i t h e r

e n d o f t h e c a r r a i g e . T h e r o l l e r o r d r u m i s l a r g e , h o l l o w a n d p e r f o r a t e d a n d i s c a r r ie d



S c our ing M a c h ine r i e s 137

on osc i l l a t ing a r m s p ivo te d a t e i the r e nd o f the ba se o f the c a r r aige . Th e f a b r i c i s

sa tu r a t e d wi th sc o ur ing l iquor ou t s ide in a n i ron t a nk [F ig . 5 - 6 (b ) ] . The ba tc h r o l l e r

i s t he n p la c e d on the c a r r a ige a nd pus he d in to the k i e r on gu ide r a i ls a nd the n door

i s c lo se d . Th e f a b r i c is w oun d f r om o ne ro l l e r t o the o the r du r ing the sc our ing

pr oc e ss . Ho t s c our ing l iquor i s c i r c u la t e d by the c e n t ri f uga l pum p a nd i s c on t inu -

ous ly sp r a ye d o ve r the f ab r i c a s i t pa s se s f r om one r o l l e r t o the o the r. S c ou r ing i s

don e u nd er a pressu re of abo ut 301b/in 2.

5 . 3 . 3 J i g proc e s s

F a b r i c s c a n b e d e s i z e d a n d s c o u r e d i n o p e n w i d t h f o r m u s i n g a j i g g e r , w h i c h i s

one o f the o lde s t a nd m os t un ive r sa l m a c h ine in t e x t i le f in i sh ing . A c e n t r a l ly c on-

t r o ll e d f u l ly a u tom a te d j igge r ( F ig . 5 - 7 ) to s e c u r e im pr o ve d p r o c e ss ing qua l i ty w i th

F igur e 5 - 7 . N e w ge ne r a t ion o f j igg e r s ( C our t e sy o f Asy s t S .L . , S a ba de l l ).

r e d u c e d o p e r a t o r i n v o l v e m e n t is s h o w n . G e n e r a l ly , th e g o o d s a r e b a t c h e d o n t o

r o l l s a nd g ive n 6 to 15 e nds on the j i g th r ough the sc our ing so lu t ion a t bo i l ing

te m p e r a tu r e . Af t e r s c our ing the goods a r e r in se d se ve r a l ends on j ig . I n th i s p r o -

c e s s the r e i s da nge r o f oxy c e l lu lose f o r m a t ion by ho t a lka l ine so lu t ion in p r e se n c e

of ai r. C lo se d j igge r s a r e u se d f o r ope r a t ion unde r inc r e a se d p r e s su r e .

A t the e nd o f e igh t i e s j i gge r s w e r e a l r e a dy c on t r o l l e d by m ic r op r oc e sso r sys t e m

a n d t o d a y m i c r o p r o c e s s o r t e c h n o l o g y e n a b l e s a ll j i g g e r s t o b e c o n n e c t e d t o a p e r -

sona l c om p ute r . A l l p r oc e s s da ta , f rom loa d ing the f ab r i c, s c our ing , wa sh in g a nd

un loa d ing , i s sto r e d a nd c an be r e que s t e d a ny t im e f o r subs e que n t p r oc e ss ing . I na dd i t ion to the poss ib i l i t y o f m a jo r a u tom a t ion , t he m a c h ine c a n be supp l i e d wi th





S c o u r i n g M a c h i n e r ie s 139

. . . . S T E A M

E S T E A M / A I R

F i g u r e 5 - 7. C l o s e d - t o p J - B o x s y s t e m

(Du - P o n t t y p e ) .

F ig u r e 5 - 8 . Op en - to p J - Bo x s y s t em

(Becco t y p e )

c lo th . In s tead o f r o p e f o r m a m u l t i - s t ag e J - Bo x in o p en w id th f o r m can a l s o b e

u s ed w i th a d w e l l tim e o f 8 - 1 0 m in i n J - Bo x . T h e s c o u r ed f ab r ic i s w as h e d o u t s id eh e a v i n g a c o u n t e r c u r r e n t a r r a n g e m e n t a t te m p e r a t u re o f a b o u t 7 0 -8 0 ~

5 . 5 . 2 O p e n w i d t h r o l l e r s t e a m e r

T h e f ab r i c i n o p en w id th f o r m i s p ad d ed (F ig . 5 - 9 ) t h r o u g h th e s co u r in g s o lu -

A l k . ~ l ~ I L u f f b r o l

a p p l : l .r

" d e : q 'h : ] . o gS b c ~ k .q C e .q m "r o.'$,

I . - .5 CO .pa x" tm,e 'n t

- . i i -

"i

...

I m p r e ~ o ~ C • v a t S t : e . am e . r Op,= .n soape r

F ig u r e 5 - 9 . Co n t in u o u s s co u r in g o f P o ly es t e r / Co t to n b l en d s [4 ].

t i o n t o a t l e a s t 1 00% p ick - u p a t 60~ w i th a r u n n in g s p eed o f 60 m / m in an d t h en

p a s s e d t h r o u g h a s h o c k s te a m e r . T h e re s i d e n c e t im e i n t h is s t e a m e r m a y r a n g e

f r o m 3 0 s ec to 5 m in . T h e u s u a l t im e i s 1 t o 2 m in ex p o s u r e t o w e t s t eam a t 1 00 to




1 1 0~ T h e a m o u n t o f f a b ri c i n s id e th e s t e a m e r is a b o u t 6 0- 1 0 0 y d s w i t h a p r o d u c -

t i o n ra t e o f a b o u t 6 0 m / m i n . T h e f a b ri c i s t h e n w a s h e d i n o p e n s o a p e r a t 7 0- 8 0 ~w i t h c o u n t e r c u r r e n t fl o w a r r a n g e m e n t .

5 .5 .3 B a t c h o r r e b a t e h i n g s y s t e m [5 ]

I n th i s sy s t e m ( F ig . 5 - 1 0 ) th e r e a r e t wo w i n d i n g sy s t e m s , o n e a b o v e t h e a n o t h e r .

O

. i l

. .. .. .. .. .. .. .. .. .. . : . . . . . . . . . : ~ ~ - , . . . _ . .. .. . ~ . ~ . . . ~ , , - . ~ -

I

F i g u r e 5 - 1 0. C o n t i n u o u s r e b a t c h i n g s y s t e m .

T h e c l o t h i s b a t c h e d i n t o t wo su p ,

l aye r comes f rom the o the r l aye r ,~ ,~ , ~ , ,~ ,~,,~, ~ , , , , ~ , ~ , . , u , , ~ ~ , ~ , ~ , , H u , , ~ y , , , ~ , , , ~ , ~

f r o m t h e i m p r e g n a t i o n d e v i ce . A s s o o n a s t h e b a t c h i s c o m p l e t e o n t h e f i rs t w i n d e r ,

t h e d i r e c t io n o f ro t a t io n is r e v e r s e d a n d t h e s e c o n d l a y er , w h i c h c o m e s f ir s t f ro m

t h e i m p r e g n a t i o n s q u e e z e r , i s le d to t h e s e c o n d w i n d e r b e l o w t h e e n t e r in g c l o th ,

wh i l e t h e o t h e r la y e r , wh i c h h a s b e e n c o m p l e t e l y a g e d , l e a v e s th e r e a c t io n c h a m b e r .

F o r r e a c t i o n p e r i o d o f a b o u t 1 - 2 h , t h e sy s t e m a l l o ws f a b r i c t r e a t m e n t w i t h a p r o -

d u c t i o n s p e e d a r o u n d 1 2 0 m / m i n . T h e m a i n d i s a d v a n t a g e s o f t h is s y s t e m a r e : ( i) it

i s su i ta b l e o n l y f o r tr e a t m e n t o f fa b r i c s w i t h s a m e w i d t h a n d ( i i) m o i r e e f f e c t (wa t e rm a r k s ) c a n n o t b e a v o i d e d .

5 .5 .4 V a p o r l o e s y s t e m

T h e c l o t h in o p e n w i d t h f o r m i s fi rs t s a tu r a t e d w i t h s o d i u m h y d r o x i d e s o l u t io n

( 5 - 9 % ) a l o n g w i t h w e t t i n g a g e n t a t 7 0~ p a d d e d a n d t h e n e n t e r e d i n to v a p o r l o c

r e a c t i o n c h a m b e r w h i c h o p e r a t e s a t 3 0 l b /i n 2 ( 2 a t m . ) a t a te m p e r a t u r e o f 1 34 ~

w i t h a r e a c t i o n t i m e o f 90 - 1 2 0 s e c (F i g . 5 - 1 1 ). T h e f a b r ic i s d e p o s i t e d o n r o l l e r - b e d

sy s t e m a n d t h u s a l l o w s t h e f a b r ic t o b e i n a r e l a x e d s t a te i n s id e t h e p r e s su r e c h a m -

b e r [ 6 , 7 ] . T h e f a b r i c p a s se s i n b e t we e n t h e l o w f r i c t i o n t e f l o n m a t e r i a l a n d t h e

c e n t r e b e a m s p e c ia l s e a l s e n a b l e s t h e g e n e r a t io n o f n e c e s s a r y p r e s s u r e i n s id e t h e




F ig u r e 5 - 1 1 . M a th e r & P la t t co n t in u o u s o p en - w id th p r e s s u r e r eac t io n c h am b er [8 ].

s t eam er . T h e c lo th co n t en t i n s id e th e s t eam er is ab o u t 2 00 m e te r s . T h e p r o d u c t io n

s p eed i s o f th e o r d e r o f 1 2 0 m / m in . T h e g o o d s a f t e r s co u r in g a r e w as h e d o f f f ir s t

w i th h o t w a t e r an d t h en w i th co ld w a te r .

5 .5 .5 H i g h p r e s s u r e K l i e n e w e f e r r o l l e r s t e a m e r

Co nt inuou s p roce ss ing p ressure s team er o f Kl iene we fer (F ig . 5 -12) u t i li ses ro l le r

F i g u r e 5 - 1 2. H i g h p re s s u r e ro l l e r s t e a m e r ( C o u r t e s y o f K l i e n e w e f e r s G m b H . ) .

s t eam er w h ich o p e r a t e s a t 3 a tm . p r e s s u r e i n d w e l l tim e to 3 0 - 1 80 s ec fo r a s o d iu m

h y d r o x id e im p r eg n a t io n co n cen t r a t i o n eq u a l t o 60 - 1 00 g/1 a t 1 3 0 -1 4 0~ T h e p r o -

d u c t io n s p eed i s o f t h e o r d e r o f 3 0 - 60 m / m in d ep en d in g o n t h e cap ac i t y o f t h e

v es s e l . Hy d r a u l i c s ea l i n g h ead s a r e s u b j ec t ed t o a p r e s s u r e i n s id e t h e v es s e l w h e r e

th e c lo th i s g u id ed o n r o l l e r s . T h e s ea l i n g h ead s p e r m i t co n t in u o u s c lo th f eed in gand de l ivery [9 ] .



142 S c our ing M a c h ine r i e s

5 . 5 . 6 C o n v e y e r s t o r a g e s t e a m e r s y s t e m

A n o t h e r w a y o f s to r i n g i m p r e g n a t e d f a b ri c c o n s i s ts o f t h e u s e o f a c o n t in u o u sp i l e s to r a ge s t e a m e r whe r e the c lo th is p l a i t e d dow n on to c on ve ye r be l t s f o r ne c e s -

sa r y t im e [ 10 ] . I n th i s sys t e m the a c c um ula t ion o f goods i s suc h tha t t he r isks o f

c r e a s ing a r e no t sup pr e s se d .

5 .5 . 7 R o l l e r b e d s t e a m e r w i t h p r e - s w e l l in g z o n e

I n th i s sy s t e m the f a b r ic in ope n w id th f o r m i s fi rs t im pr e gna te d wi th a s c ou r ing

so lu t ion a nd the n gu ide d to r o l l e r s f o r a t im e su f f i c ie n t f o r swe l l ing ( F ig . 5 - 13).

F i g u r e 5 - 1 3 . R o l l e r b e d s t e a m e r ( C o u r t e s y o f K l i e n e w e f e r s G m b H ) .

The f a b r ic i s p r e - swo l l e n in the t igh t - s t ra nd r o l l e r s e c tion be f o re be ing p la i t e d dow n

on to the r o l l e r be d f o r the r e qu i r e d t im e . T he r o l l e r be d c onv e ye r c a n be r e p la c e d

by a c onv e ye r be l t. Th i s k ind o f in s t a l l a tion pe r m i t s 6 - 20 m in dw e l l t im e a t 10 0 ~

f o r N a O H c o n c e n t r a t io n a r o u n d 3 - 6 % w i t h a p ro d u c t i o n s p e e d o f ab o u t 1 00 m /

m i n . V a c u u m i m p r e g n a t i o n o f th e f a b r ic w i th t h e s c o u r in g s o l u ti o n b e f o re s t ea m -

ing i s som e t im e s r e c o m m e nd e d f o r r a p id w e t t ing o f the goo ds [ 11 ] .

5 . 5 . 8 C o n t i n u o u s r e l a x i n g / s c o u r i n g m a c h i n e

R o ta r y w a she r s ( se e c ha p te r 7 ) ha ve be e n use d a s a n ope n wid th t r e a t ing a p pa -

r a tus o f ba t c h type ; t h i s ha s a l a r ge e f f ec t , bu t ha s su c h de m e r i ts a s f e a r o f r e l a x -

a t ion spe c ks ( spo t m a r k ) a nd f l a w ( de fe c t , spo t e tc .) a nd ine f f ic i e nc y . He nc e c on-

t inuous r e l a x e r ha s be e n de ve lope d . T he a bse n c e o f t e ns ion i s f a vour a b le f o r re l a x -

ing a nd e a c h m a c h ine m a nuf a c tu r e r ha s g ive n v ib r a t ion to the f a b r i c in h i s ownw a y . M e c h a n i c a l i m p a c t s i n th e f o r m o f b e n d i n g , p r e s si n g , v i b r a ti n g a n d r u b b i n g

a c t ion a r e u t i l i s e d f o r be t te r e f f e c t du r ing r e l a x ing p r oc e ss .




In t h e Mez za r a r e l ax in g m a ch in e (F ig . 5 - 1 4 ) t h e fab r ic s u s p en d e d i n lo o p s f r o m

1 . D raw ro l l e r s fo r con t ro l l ing feed2 . Pre -w e t t ing ba th wi th d r iven ro l l e r3 . D raw ro l l e r s4 . T r o u g h w i t h V - s l o t

5 . M a in t ank6 . S aw- to o th ra i l s7 . C e m t r i f u g a l p u m p w i t h f i lt e r

F ig u r e 5 - 1 4 . Mez ze r a ( I ta ly ) o p en - w id th r e l ax in g / s co u r in g u n i t.

a s e r ie s o f p a r a l l e l r o d s m o v e f o r w ar d v e r y s lo w ly a lo n g t h e l en g th o f t h e m ach in e .

T h e s e r o d s a r e m o u n ted i n t r ack s o n e i th e r s i d e o f t h e m ach in e t an k . T h e y a r e

lo ca t ed j u s t b e lo w th e s u r f ace o f t h e l iq u o r . T h e r o d s r i s e u p a s aw to o th r am p an d

th en d r o p , s ay ab o u t 5 cm , t h u s g iv in g an o p p o r tu n i ty f o r th e f ab r i c i n co n t ac t w i th

th e r o d t o b e s l i g h t l y d i s p l aced . T h e f ab ri c i s ca r e f u l ly g u id ed i n to t h e cen t r e o f th e

m ach in e an d f ed o v e r a fu l l w id th ree l , in to a V- s h ap ed t r o u g h , w i th an o p en b o t -t o m . T h e t r o u g h i s k ep t h a l f f i ll ed w i th w a te r w h ich p u l l s t h e f ab r i c o f f th e r ee l an d

ca r r i e s i t d o w n in to t h e b a th t o f o r m a l o o p , g en e r a l l y ab o u t 80 cm lo n g . T h e m ax i -

m u m s p e e d o f o p e ra t io n i s d i c ta t e d b y t h e s p e e d o f t h e w a t e r p o u r i n g o u t o f th e

b o t t o m o f t h e V - t ro u g h . T h e b o t t o m o f t h e tr o u g h s l o w l y m o v e s f o r w a r d w i t h t he

ad v an ce o f t h e r o d , b e in g l o ad ed , an d t h en ab o u t ev e r y 5 t o 6 s ec r o t a t e s b ack t o

s t a r t l o ad in g t h e n ex t r o d . Af t e r ca r r y in g t h e f ab r i c t h r o u g h th e m ach in e t h e r o d s

m o v e d o w n to th e b o t to m o f t h e b a th an d r e tu r n to th e f eed en d . T h e f ab r ic b e in g

im m er s ed i n t h e l i q u o r in l o o p f o r m f o r ab o u t 2 0 r a in h as a g o o d ch a n ce t o r e l ax .

T h e f a b ri c i s t h e n d r a w n o f f b y r o l le r a n d s p r a y e d w i t h w a r m w a t e r a n d t h e n c o l d

w a t e r b e f o r e b e i n g p l a i te d d o w n , o u t s id e t h e m a c h i n e .




5 . 5 . 9 S o l v e n t s c o u r i n g m a c h i n e s

S c o u r i n g o f k n i t te d g o o d s , w o o l a n d b l e n d e d w o v e n f a b r ic s i n d i s c o n t in u o u sr o t a r y - d r u m w a s h i n g m a c h i n e s h a s b e e n e s t a b li s h e d in m a n y c o u n t r ie s f o r a n u m -

b e r o f y e a rs . E q u i p m e n t f o r co n t i n u o u s p r e p a r a ti o n a n d d y e i n g f r o m n o n - a q u e o u s

so lve n t ha v e be e n de v e lope d by se ve r a l c om pa n ie s ( Ta b le 5 .1 ).

T A B L E 5 . 1

C o n t i n u o u s S o l v e n t S c o u ri n g M a c h i n e s

C o m p a n y U n i t

B o h l e r a n d W e b e r [ 1 2 -1 4 ]ICI [15]

B ruc kn er [ 16, 17]

D o w [ 1 8 ]

R i m m e r [ 1 9]

R i g g s a n d L o m b a n d [ 20 ]

N e i l & S pe nc e r [21 ]

C 1600 / C 1800M a r ka l

Solvani t

D o w S c o u r i n g S y s t e m

Vibr o S c our

S c our - k le e n

L iba te x

In ICI ' s M arka l p rocess (Fig . 5-15) the dry c lo th f i r s t passes throu gh t r ich loroe t -

F i g u r e 5 - 1 5 . C o m m e r c i a l M a r k a l ( I C I ) m a c h i n e a n d c o m b i n e d w a s h e r .

h y l e n e ( T C E ) i n t h e d e w a x i n g v e s s e l w h i c h i s d i v i d e d i n t o n u m b e r o f s e p e r a t e

c o m p a r t m e n t s . F r o m t h e l as t c o m p a r t m e n t t h e c l o th p a s s e s t h r o u g h a s o l v e n t s e al

a n d h e a v y m a n g l e w h e r e m u c h e x t r a i n e d s o l v e n t is r e m o v e d f ro m t h e c l o th . T h e

c lo th the n pa s se s th r ough a c ha m be r in to wh ic h s t e a m i s i n je c te d . Thus r a p id e va po -,.

r a t ion o f so lve n t i n the c lo th a nd the m ix tu r e o f s t e a m a nd TC E va pour i s c on -

de n se d a nd r e tu r ne d to the so lve n t s e a l wh e r e the so lve n t a nd wa te r a r e s e pe r a te d .I n a l te r na t ive m e thod , t he so lve n t is r e m ove d f r om the c lo th by the use o f a n e n -

c lose d ho t w a te r ( 95~ ba th in s te a d o f s t e a m c ha m b e r [22 ]. Af t e r pa s s ing th r ough




the wa te r wa sh t a nk , t he c lo th l e a ve s the sc our ing m a c h ine sa tu r a t e d wi th wa te r .

T h e M a r k a l I I p r o c e s s c o n s i s t s o f e f fe c t in g s i m u l t a n e o u s s c o u r i n g a n d d e s i z i n g b y

u s i n g s u s p e n s i o n o f e n z y m e i n T C E a n d s u r f a c ta n t s o lu t io n . T h e t r e at e d s a m p l e i s

the n pa s se d th r oug h s t e a m ing c ha m be r f o r 10 - 20 se c w he r e the so lve n t i s f l a she d -

o f f. The f a b r ic i s the n g ive n no r m a l w a sh to r e m ov e the s i z e [23 , 24 ]. M a r ka l I I I

p r oc e ss c om bine s b l e a c h ing w i th sc our ing a nd de s i z ing by us ing e m u ls ion o f a que -

o u s h y d r o g e n p e r o x i d e i n th e T C E - s u r f a c ta n t s o lu t io n , a g a i n f o l l o w e d b y s t e a m i n g

a n d w a s h i n g - o f f.

A n o t h e r c o n t i n u o u s s o l v e n t s c o u r in g m a c h i n e f o r k n i tt e d a n d w o v e n f a b ri c s is

show n in F ig . 5 - 16 . The B r uc kn e r S o lva n i t c on t inuous p r oc e ss i s u se d f o r s im u l t a -

ne ou s sc ou r ing , c l e a n ing a nd f o r sh r ink ing . The c lo th is t r a nspor t e d b y a pa te n te d

F igur e 5 - 16 . C o n t inuo us so lve n t s couring , a nd f in i sh ing m a c h ine

( C ou r t e sy o f S pe r o t to R im a r , I t aly ).

p a d d l e w h e e l w h i c h e n s u r e s t h o r o u g h r e m o v a l o f c o n t a m i n a n t s b y c o u n t e r c u r r e n t

f lo w o f f r e s h p e rc h l o r o e t h y l e n e . R e l a x a t i o n a n d b u l k i n g o f k n i t t e d g o o d s O c cu r

dur ing so lve n t f l a sh - o f f . .

5 . 6 W o o l S c o u r i n g M a c h i n e s

S c o u r i n g m a c h i n e s o f w o o l d e p e n d o n t h e k in d o f w o o l t o b e s c o u r e d i .e . r a w

w o o l , h a n k f o r m o r w o v e n f a br ic s . S c o u r i n g o f w o o l c a n b e c a r ri e d o u t i n b a t c h o r

c o n t i n u o u s p r o c e s s , a q u e o u s o r s o l v e n t m e d i a a n d r o p e o r o p e n w i d t h f o r m .

5 .6 .1 R a w w o o l s c o u r i n g m a c h i n e s

I n the c onve n t iona l s c our ing m a c h ine ( F ig . 5 - 17 ), r a w w oo l i s p r op e l l e d th r ou gh

a t a nk f i l l e d w i th wa r m wa te r c on ta in ing de te r ge n t , r a ke d th r ough the bowl , c on -v e y e d b y m e a n s o f a tr a n s fe r m e c h a n i s m t o s q u e e z i n g r o l le r s a n d t h e t i c a r ri e d i n to

a no the r s im i l a r t a nk . The bow ls ha ve f a l se bo t tom s c ons i s t ing o f pe r f o r a t e d p l a t e s




F igu r e 5 - 17 . S c our ing o f r a w w oo l in tr a d i t iona l s c r ou r ing m a c h ine s .

wh ic h a l low r e m ova l o f d i r t f r om the woo l to f a l l t h r ough the pe r f o r a t ions wh i l e

p r e v e n t i n g t h e f ib r e f ro m p a s s i n g . T h e w o o l m a y p a s s t h r o u g h f o u r o r m o r e t a n k s

in th i s wa y , un t i l e ve n tua l ly i t is r in se d in c l e a n wa te r .

T h e r a w w o o l i s al so s c o u r e d b y s o m e u n c o n v e n t i o n a l m a c h i n e s [ 25 ]. I n th e

F l e i s s n e r m a c h i n e l o o s e w o o l i s c o n v e y e d t h r o u g h t h e b o w l b y a s er ie s o f s u c ti o n

dr um s ( F ig . 5 - 18 ) . The f low o f l iquo r th r ou gh the wo o l a nd in to the th r e e suc t ion

F igur e 5 - 18 . The F le i s sne r s c our ing bow l .

d r um s i s done by pum ps th r ou gh the pe r fo r a t e d su r f a c e o f the d r um f r om ou t s ide to

ins ide . I n th i s type , t he e f f ic i e nc y o f r e m ov ing im pu r i ti e s i s c om pa r a t ive ly l e s se r

due to the ge n t l e s c ou r ing a c t ion a nd a r e a l so c om pa r a t ive ly c os t l i e r tha n the c on-

v e n t i o n a l m a c h i n e .

I n the j e t s c our ing m a c h in e s ( F ig . 5 - 19 ) the woo l t r a ve l s on a c onve y e r be l t o r a

Figure 5-19 . Je t scour ing bowl [26 , 27 ] .




p e r f o r a t ed d r u m an d th e s co u r in g l i q u o r i s s p r ay ed o n t h e f i b r e t h r o u g h lo w p r e s -

s u r e j e t s . Les s f e l t in g t ak es p l ace d u e to lo w v e lo c i t y o f j e t an d g en t l e m o v em en t o f

w o o l .

In t h e CIS R O L o - f lo s y s t em [2 8 ], f ir s t o n e o r tw o b o w ls o f co n v en t io n a l m a-

ch in e a r e rep l ac ed an d w a s h p l a te b o w l s (F ig . 5 - 2 0 ) a r e u s ed i n s t ead . T h e w o o l i s

J

F ig u r e 5 - 2 0 . Was h p la t e b o w l s u s ed i n Lo - f lo p r o ces s .

w a s h ed d o w n a p e r f o r a t ed p l a t e i n to t h e s q u e ez in g r o l l e r b y j e t s o r s p r ay s o f s co u r -

in g li q u o r . L iq u o r s f r o m L o - f lo u n i t an d th e co n v e n t io n a l b o w l s a r e b o th r ecy c l ed

th r o u g h in t e r co n n ec t ed l o o p s i n co r p o r a t i n g h eav y s o l i d s s e t t l i n g an d cen t r i f u g a l

o p e r a t i o n . T h i s h as t h e s h o r t e s t p o s s ib l e b o w l an d h as p o o r s co u r in g e f f i c i en cy .

T h e p r o c es s i s m a in ly u s ed t o r eco v e r g r eas e an d f o r p o l l u t i o n co n t r o l.

5 . 6 . 2 W o o l h a n k s c o u r i n g m a c h i n e

W o o l l en an d w o r s t ed y am s , u n l e s s d r y s p u n co n ta in s i g n i f ican t am o u n t o f l u b ri -

ca t i n g o i l an d a r e u s u a l l y s co u r ed i n h an k f o r m in a co n t in u o u s s co u r in g m ach in e .

T h e h a n k s a r e t r an s p o r t ed t h r o u g h th e s co u r in g s e ts e i th e r b y t ap e (F ig . 5 - 2 1 ) s y s -

t em o r b y b a t t r i ce s (F ig . 5 - 2 2 ). Us u a l ly , t h e s e t s h av e f o u r b o w l s " tw o s co u r b o w ls ,

o n e r i n s e b o w l an d a f i n a l b o w l w h er e ac id i f i ca t i o n an d m o th p r o o f in g i s ca r r i ed

o u t . T h e r e i s a p a i r o f s q u eeze r o l l e r b e tw een each b o w l . T h e t o p r o l l e r i s u s u a l l y

l ap p ed w i th w o o l o r co t t o n s l i v e r an d t h e b o t to m r o l l e r is m ad e o f m e ta l . P r e s s u r e

i s ap p l i ed t o h av e an ex p r es s io n o f ab o u t 60%. T h e ch a r ac t e r i s t i c f ea tu r e s o f t h e

tw o ty p es o f m ach in es a r e s u m m er i s ed i n T ab l e 5 .2 . It i s n o r m a l t o s co u r o n ly 1 -2



148 Scour ing Machiner ies

Figure 5-22 . Pr incip le of a bat t r ice scour ing m achine .



S c our ing M a c h ine r i e s

T A B L E 5 . 2

C h a r a c t e r is t ic F e a t u r e s o f Y a m S c o u r i n g M a c h i n e s [ 29 ]

149

Bat t r ice Tape

L e n g t h 0 f b o w l s ( m )

W i d t h o f b o w l s (c m )

D e p t h o f b o w l s (c m )

Ca pa c i ty (1)

R u n n i n g s p e e d (m / m i n )

2 .5-4 1 .5-3 .5

8 0 - 135 7 0 - 120

55-85 55-85

1 6 0 0 - 2 5 0 0 5 0 0 - 2 2 0 0

4.5 9 .0

, to n s o f y a m i n s u c h t y p e s o f m a c h i n e s . D u e t o l o w e r r u n n i n g s p e e d , b a t t ri c e m a -

c h i n e s g i v e l o w e r i m m e r s i o n t i m e s c o m p a r e d t o 6 t o 1 2 s e c g i v e n b y t a p e m a -

c h i n e s. T h e b o w l s a re u s u a l l y h e a t e d b y d i r e c t s te a m t h r o u g h p e r f o r a t e d p i p e s o r

c on t r o l l e d s t e a m va lve s .

W o o l l e n y a m s c a n a ls o b e s c o u r e d i n p a c k a g e s s u c h a s in th e f o r m o f c o n e s o r

c h e e s e s . S m a l l b a tc h e s m a y b e s c o u r e d i n K l a u d e r - W e l d o n m a c h i n e o r o n a D o l l y

w a s h i n g m a c h i n e .

5 .6 .3 W o o l f a b r ic s c o u r i n g m a c h i n eB a tc hw ise r ope sc ou r ing in the Do l ly [30] u s ing soa p a nd sod a is w id e ly p r a c -

t is e d . The D o l ly c ons i s ts o f a wo ode n ve s se l ac r oss a nd ove r the w inc h va t i s m oun te d

a p a i r o f h e a v y w o o d e n s q u e e z i n g r o ll e rs . M o d e r n m a c h i n e s a re d e v e l o p e d

( Fi g . 5 - 2 3 ), i n w h i c h t h e o p e r a ti o n s o f w a s h i n g / f u l li n g o r o f h i g h s p e e d w a s h i n g

c a n b e c a r r ie d o u t w i t h o u t t h e n e e d f o r a d d i ti o n a l m a c h i n e r y . C o m b i n e d s c o u r in g

a n d m i l l i n g s a v e ti m e , m a n - p o w e r , w a t e r a n d e n e rg y . T h e c l o th i s r u n t h r o u g h t h e

sc our ing l iquor a nd the sc ou r ing i s c on t inue d t il l the f a b r i c i s cl e a ne d . I n one sys -

t e m j e t s o f s c ou t ing l iquor a r e f o r c e d in to a nd th r ough the f a b r i c r ope s a s the y pa s s

t h r o u g h a j e t b o x i m m e d i a t e l y i n f r o n t o f th e n i p ro l le r s . B y m e a n s o f tw o t ra n s -

po r t ing a nd sque e z ing r o l l e r s ( 7 ), t he f a b ri c i s c om pr e sse d in to the f u l l ing t a nk ( 9) ,

a nd a s t a r c y l inde r ( 10 ) , ope r a t ing a t va r i a b le spe e d , e na b le s the de s i r e d pa c k ing

de ns i ty in the f u l l ing t a nk to be a c h ie ve d w i th the g r e a te s t a c c u r a c y a nd r e p r odu c -

ib i li ty . T he se t t ing o f the p r e s su r e a t t he f u l l ing f la p ( 11) l e a ds to a m or e un i f o r m

f u l l ing e f f e c t . The m a te r i a l i s c onve y e d o u t o f the f u l l ing t a nk v ia the c y l inde r ( 10 )

and a f te r pass ing o ver ano ther s ta r cy l inder (13) , r e turns to the fu l l ing l iquor . In thec a se o f h ig h - sp e e d w a sh ing , o r a f te r f u ll i ng , the c y l inde r ( 13 ) op e ns - ou t the f a b r i c




F i g u r e 5 - 2 3 . D i a g r a m o f a s o ft a n d r a p i d s c o u r i n g a n d m i l l i n g m a c h i n e( C o u r t e s y o f C I M I C e r r e t o C a s t e l l o , I t al y ) .

a n d t h r o w s i t a g a i n s t t h e b a f f l e p l a t e ( 1 5 ) . T h e h i g h - s p e e d w a s h i n g m a c h i n e i s

a v a i l a b l e w i t h 2 a n d 4 f u l l i n g t a n k s ( J - B o x e s ) , w i t h t h e p o s s i b i l i t y o f o n e o r t wo

e n t r ie s p e r t a n k . T h e f u l li n g t a n k c a p a c i t y m a y b e 5 0 - 4 0 0 k g f o r th e m a c h i n e w i t h

t w o t a n k s a n d 5 0 - 6 0 0 k g f a b r ic f o r th e m a c h i n e w i t h fo u r ta n k s. T h e w o r k i n g s p e e d

c a n b e i n f i n i t e l y v a r i e d b e t w e e n 6 0 - 4 0 0 m / m i n i n a d d i t i o n t o t h e c h o i c e o f 5

p r e s e l e c t a b l e s p e e d s , w h i c h m a y b e c h a n g e d a s n e c e s s a r y . T h e r e a r e s o m e m a -c h i n e s w h i c h c a n l o a d u p to 1 2 r o p e s o f l ig h t f ab r ic s . T h e w e l l - k n o w n b a g s t i tc h i n g s

f o r a l l f a b r i c s a r e n o t n e c e s sa r y a n y m o r e a n d i t i s g u a r a n t e e d t h e a b se n c e o f t h e

t r a d i t i o n a l p r o b l e m s o f c r e a se s , a b r a s i o n s , t e a r s a n d h o l e s a lso o n b l e n d s p a r t i c u -

l a r l y s e n s i t iv e t o t h e se d e f ec t s . T h e c l o t h a f t e r s c o u r i n g i s w a sh e d - o f f i n l u k e wa r m

wate r .

5 . 6 . 4 C a r b o n i s i n g r a n g e f o r w o o l l e n f a b r i c s

T h e c a r b o n i s i n g p r o c e s s u su a l l y c o m p r i s e s : a c i d i f y i n g - d r y i n g - c a r b o n i sa t i o n

- s c o u r i n g . T h e p r o c e s s i s s a m e f o r l o o se s t o c k a n d p i e c e g o o d s . T h e c a r b o n i s i n g

m a c h i n e ( F i g . 5 - 2 4 ) c o m p r i s e s : e n t r y f r a m e , a c i d b a t h , J - B o x r e a c t i o n , p e r f o r a t e d




t . . . . . U J I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 ~ . : , , . ~ ; ~ _ r:" + : ~ F

Figur e 5 - 24 . C a r bon i s ing r a nge f o r wo o l l e n f a b r i c

( C o u r t e s y o f F l e i s s n e r G m b H & C o . G e r m a n y ) .

d r um d r ye r w i th c a r bon i s ing se c t ion , be a t ing a nd b r ush ing un i t a nd p la i t i ng o r

ba tc h ing un i t . De pe nd ing on the f u r the r p r oc e ss s e que nc e , a ne u t r a l i s ing pha se

(Fig . 5-25) can fo l low.

- +~++~- '-" 1

. . . . . . . . . . . . . ,

- . _ z

Figur e 5 - 25 . (a ) M a c h ine c onc e p t a s pe r f o r a t e d d r u m w a sh ing r a nge ,

( b ) R o l l e r va t r a nge f o r m or e c lose ly wov e n c lo th qua l i ti e s .

The a c id ba th i s de s igne d a s a r o l l e r va t w i th s ing le f a b r i c th r e a d - in . R ubbe rc ove r e d r o l l e r s p r e s s on the uppe r gu ide r o l le r s i n o r de r to p r om ote e va c ua t ion o f

the a i r a nd so a k ing o f the f a b ri c . Wi th ou t be ing sub je c te d to e xc e ss ive sque e z ing ,

the fabr ic i s dep os i ted in J -Bo x reac t ion vesse l hold ing abou t 100 m o f fabr ic . Here

the c lo th , w h ic h i s s a tu r a t e d wi th the l iquor , ha s a m ple oppo r tun i ty to a bso r b the

a c id . Fo l low ing a n a de qua te r e a c t ion pe r iod , t he f a b r ic i s d r a wn o u t o f t he J - B ox

v ia a h igh e xpr e s s ion n ip . The e x pr e s se d l iquor i s c onduc te d ba c k to the im pr e gn a t -

ing ba th . The r e i s a l so a l i quor r e tu r n f low c onne c t ion l e a d ing f r om the r e a c t ion

ve sse l . The im pr e gn a t ing ba th i s p r ov ide d wi th a li quor c i r c u la tion f a c i l i ty wh ic h

e nsu r e u n i f o r m c onc e n t r a t ion in the ba th . The use d l iquor i s r e p le n i she d by a l e ve l

c on t r o l l er . A n a u tom a t i c t i tr a t ion s t a tion c ons ta n t ly m on i to r s the a c id .



152 S c o u r i n g M a c h i n e r ie s

The fab r ic i s then dr ied a t 80~ in pe r fo ra ted drum dryers where the dry ing a i r i s

d r a w n t h rough t he f a b r i c w h i c h e ns u re s a f a s t , ge n t l e a nd un i fo rm d ry i ng a c t i on .F i na l l y , t he d ry f a b ri c is he a t e d up to 120 -130~ on a pe r fo r a t e d d rum i n t he

carbo nis ing sec t ion , and th is tem pera ture i s m ain ta ined cons tant in the hot flue cham -

b e r , w h i c h h o l d s a p p r o x i m a t e l y 3 0 m o f cl o th . T h e d r y i n g c h a m b e r is s e p e r at e d

f rom t he c a rbon i s i ng s e c t ion by a pa r t i ti on . Fo l l ow i ng c a rbon i s a t i on t he f a b r ic i s

g u i d e d t h r o u g h a b e a t i n g a n d b r u s h i n g u n i t w h e r e t h e c o m b u s t e d c e l lu l o s e i m p u r i -

t i e s a r e r e move d a nd e xha us t e d .

A c a rbon i s i ng r a nge fo r w oo l f a b r i c s w h i c h p roba b l y a pp l i e s hydroc h l o r i c a c i d

f rom pe rc h l o roe t hy l e ne ha s be e n de ve l ope d ( F i g . 5 -26 ) .

F i gu re 5 -26 . C on t i nuous r a nge fo r s o l ve n t c a rbon i s i ng o f

w o o l l e n f a b r ic s ( C ou r t e s y o f S pe ro t t o R i ma r , I t a ly ) .

5 . 6 . 5 C r a b b i n g a n d d e c a t i s i n g m a c h i n e s

C r a b b i n g a n d d e c a t i s in g r e p r e s e n t i m p o r t a n t p r o c e s s e s i n t h e f in i s h in g o f w o o l

goods p rov i d i ng w oo l f a b r i c s w i t h a t op - l i ne s h r i nk - f r e e f i n i s h . The c on t i nuous

f i n i s h i ng l i ne fo r w or s t e ds a r e s he a r i ng - p r e s s i ng - humi d i fy i ng - de c a t i s i ng a nd

fo r w o o l l e n f a b r i c s a r e s he a r i ng - p r e s s i ng - s h r i nk i ng - hum i d i fy i ng - de c a t i s ing .

A c on t i nuou s c r a bb i ng by ove rh e a t e d w a t e r w i t hou t r ubbe r be lt ( Fi g . 5 -27 ) g i ve s

p e r m a n e n t e f f ec t w i t h b r i g h t e r a p p e a r a n c e. T h e n o t a b le i m p r o v e m e n t o f t h e f ab r ic

qua l i ty is due to the ca len der in g e f fec t in w a te r a t 110~ Th ere i s no need for use of

e xpe ns i ve rubbe r be l t s . F i g . 5 -28 s how s a c on t i nuous mul t i s e t c r a bb i ng ma c h i ne .

The k i e r de c a t i s i ng ( F ig . 5 -29 ) o f w oo l f a b r i cs i s al s o a p roc e s s fo r pe rm a ne n t l y

s e t t i ng w oo l f a b r i c s . I n t h i s w a y w oo l f a b r i c s a r e g i ve n s u r f a c e s t a b i l i t y w i t hou t



Scouring M achineries 153

Figure 5-2 8. Continuous crabbing m achine (C ourtesy of Sperotto Rimar, Italy).



154 Sco u r in g Mach in e r i e s

F ig u r e 5 - 2 9 . Kie r d eca t i s i n g m ac h in e (Co u r t e s y o f Sp e r o t t o R im ar , I t a ly ) .

l o o s in g t h e i r s h ap in g cap ac i t y i n t h e m ak in g u p p r o ces s . T em p er a tu r e , p r e s s u r e ,

m o i s t u re a n d t i m e a r e t h e p a r a m e t e r s w h i c h i n tr o d u c e p h y s i c a l a n d c h e m i c a l p r o -

ces s es i n k i e r d eca t i s in g . O n e o f t h e d i s ad v an t ag e o f k i e r d eca t i s i n g i s i ts b a t ch t y p e

m e th o d o f o p e r a t i o n . Ch em ica l d eca t i s in g o f w o o l f ab ri c s h as l o n g b een a s u b j ec t

o f d i s c u s s i o n i n b a s i c r e s e a r c h c en t re s . T h e " M e n s c h e m a p r o c e s s " ( K e t t li n g +

Br au n , H em m er ) i s a lo w ad d - o n ap p l i ca to r i n co m b in a t i o n w i th a Co n t r i p r e s s |an d a d eca t i s i n g m ach in e . M en s c h n e r an d T r i a t ex p r e s en t ed i t o n ly i n t h e f o r m o f a

" m u r a l r e l i e f ' '. T h e n e w M R p r o c e s s ( M e n s c h n e r - R o t t a c h e m i c a l d e c a t i s in g ) i s

s h o w n in F ig . 5 - 3 0 . T h e o p e r a t i o n a l s e q u en ce s o f t h e M R p r o ce s s a r e w e t f i n is h -

F ig u r e 5 - 3 0 . Un iv e r s a l p e r m an en t d eca t i s i n g m ach in e

( C o u r te s y o f M e n s c h n e r - K e t tl in g & B r a un , F R o f G e r m a n y ) .




ing , padd ing , d epend ing on the e f fec t (Rot ta ), dry ing , r edam ping (W eko) , cont r ipress

( M e nsc hne r ) a nd c on t inuous de c a t i s ing . B e f o r e the woo l f a b r i c i s t r e a t e d on theC o n t r ip r e s s the s t a b i l is ing a ge n t s o r s im i l a r p r odu c t s a r e a pp l i e d in e xa c t ly the

r i g h t a m o u n t b y t h e l o w a d d - o n r o u t e a n d t h e n c a n r e a c t c o m p l e t e l y u n d e r t h e

im pe r m e a b le C o n t r ip r e s s be l t i n the te m pe r a tu r e a nd p r e s su r e z one . The e f f e c t ive

r a nge o f a pp l i c a t ion i s f r e e ly va r i a b le . O the r c he m ic a l s tha t s e t woo l in the d r y a nd

we t s t a t e s c a n a l so be a pp l i e d . B e s ide s g r e a t ly s im p l i f y ing the f in i sh ing se que nc e ,

the p r oc e ss c u t s c os t s a nd sa ve s f loo r spa c e .

T h e e v a l u a t i o n o f t h e d e c a t i s in g e f fe c t is c o m m o n l y b a s e d o n s u b j e c t i v e e s ti -

m a te s . The ha n d le , t he g l a z e , the b r ighm e ss o f the c o lou r s , the bu lk in e s s o r ha r d -

ne ss o f t he f a b ri c a re ob ta ine d f r om the de c a t i s ing m a c h ine s , t he f low d ia g r a m s o f

whic h a r e shown in F igs . 5 .31 , 5 .32 a nd 5 .33 . The r e f o r e , i t i s r e qu i r e d f r om the

de c a t i s ing m a c h in e s tha t m a y h a ve a w ide a nd e f f e c t ive ve r sa ti l it y .

F igu r e 5 - 32 . L us t r e de c a t i s ing m a c h ine

( C ou r t e sy o f D r a b e r t S h~ Sne, Ge r m a ny) .



156 Sco u r in g Mach in e r i e s

F i g u r e 5 - 33 . P e r m a n e n t c o n t i n u o u s d e c a t is i n g m a c h i n e(Co u r t e s y o f D r ab e r t Sh ]Sn e, Ger m an y ) .

5 .7 S i lk D e g u m m i n g M a c h i n e s

P r o p e r s e l ec t i o n o f eq u ip m en t f o r d eg u m m in g o f s i l k i s e s s en t i a l t o p r ev en t

c h a f e d s u r fa c e , c h af e m a r k s , u n e v e n d e g u m m i n g a n d c h e m i c a l d a m a g e . H o w e v e r ,

t h e s e l ec t i o n o f eq u ip m en t d ep en d s o n t h e ty p e o f t h e a r ti c le t o b e p r o ces s ed .

5 .7 .1 Y a r n d e g u m m i n g m a c h i n e s

Si lk y a r n i s n o r m a l ly d eg u m m ed in t h e h an k f o rm . In t h e p ac k (b eck ) , t h e h an k s

a re n o r m a l l y h u n g o n p o l i s h e d w o o d o r m e t a l r o d s w h i c h a re s u b m e r g e d i n t h e b a t h

an d tu r n ed b y h an d . Al t e r n a t i v e ly , h an k an d s p r ay d y e in g m ach in es can a l s o b e

u s e d f o r d e g u m m i n g o f s il k i n y a m f o rm . I n th e f o a m b o i l i n g p r o c e s s f o a m p r o -

d u c e d b y s o a p b a t h c o m e s i n c o n t a c t w i th s i l k a n d th u s c a u s e s d e g u m m i n g .

5 . 7 . 2 P i e c e g o o d s d e g u m m i n g m a c h i n e s

D e g u m m i n g o f p i e c e g o o d s c a n b e d o n e o n b e c k o r p a c k s y s t e m a n d th e s t a r

m ach in es (F ig . 5 - 3 4 ) a r e p a r t i cu l a r ly s u i t ab le f o r d e l i ca t e a r t ic l e s . In t h e b eck s y s -

t em w i th s t r i n g s t h e p i eces a r e h u n g o n b am b o o o r s m o o th m e ta l r o d s s o t h a t t h eg o o d s r e m a i n s u b m e r g e d i n t h e d e g u m m i n g b a th . T h e m a i n d i s a d v a n t a g e o f t h is

sys te m i s chafe m arks (b lanch ed p lace s ) o r ir r egu lar i t i es in the fo rm o f spo ts . In the

w e l l k n o w n s ta r m a c h i n e s t h e g o o d s m a y b e h u n g f r o m a b o v e o n l y i n t h e c a se o f

v e r t i ca l s im p le s t a r o r t h e g o o d s m ay b e a t t ach ed f r o m b e lo w o n h o o k s a s w e l l a s

h an g in g f r o m ab o v e i n t h e ca s e o f v e rt ica l d o u b le s ta r o r m ay b e h o r i zo n t a ll y d o u b le

s t a r s y s t em . Du r in g d eg u m m in g s h r in k ag e t ak es p l ace an d h en ce t h e s ta r m ach in es

a r e s o d es ig n e d t h a t th e h an k s can b e m o v ed a lo n g t h e a r m s o f t h e s t ar , t h u s a l l o w -

in g f o r s h r in k ag e .

In t h e co n t in u o u s d eg u m m in g m ach in es (F ig . 5 -3 5 ) th e g o o d s a r e h u n g in l o o p s



S c our ing M a c h ine r ie s 157

Figur e 5 - 35 . C on t inuous bo i l ing o f f m a c h ine f r om M e z z e r a .

on rods wh ic h r e m a in f u l ly subm e r ge d in the ba th a nd m ove c on t inuous ly f o rwa r d .

A r t ic l e s w i t h t ig h t , s m o o t h w e a v e s m a y b e d e g u m m e d o n t he j ig . W i n c h e s a n d

j e t s a re n o t g e n e r a ll y re c o m m e n d e d f o r c o m p l e t e d e g u m m i n g , b u t o v e r fl o w m a -

chines can be used for kni t ted goods .



158 Scour ing Ma chiner ies

R E F E R E N C E S

1 J .T . Marsh , A n In t roduct ion to Tex t i le F in ish ing , (J . T . Ma rsh Ed . ) Ch apm an

and Hall , London (1946) .

2 S .R . T ro tm an and E. L. Throp , The Pr inc ip les o f Bleach ing and F in ish ing of

Cotton (S. R. Trotman and E. L. Throp Ed.) Griff in , London (1927) .

3 D. Ang stam an n and K. H. Ru cker , Texti l Praxis Int . , 28 (1973) 464.

4 BA SF Man n u a l , "D y e in g an d F in ish in g o f P o ly es te r F ib r e s" .

5 P. B uch m ann , M ell iand Texti lber . , 35 (1954) 304.

6 C. Du ckw orth , J . V. Horsely and J. J . Thw aites, J. Soc. Dy ers Co lourists , 88

(1972) 281.

7 J. T. B ow den , Tex ti lvered lung, 8 (1973) 173.

8 M ath er & Plat t Ltd. , Int. Dye r , 145 (1971) 206.

9 J. J. Th w aite s, Indian Text. J., 84 (1973) 159.

10 M ath ieso n A lka l i Corp . , Am er . Dye stu f f Rep . , 33 (1944) 536 .

11 G. Schiffe r, Int. Dy er, 159 (1978) 463.

12 Sch nerr ing, Texti lve redlun g, 8 (Jan 1973) 31.13 Seiber , Am er. Dyes tuf t Rep . , 59 (Oct 1970) 44.

14 Se iber , DC R O Leices te r Con ference (Oct 1972).

15 Su i te r and Sh ipman, AA TC C Sy m posium , Tex t i le So lven t Tech nology , ( Jan

1973) 109.

16 Buckner - Appara tebau Miche ls tad t , BP, 1 ,306, 777 (18 Feb 1970) .

17 Kolb , AAT CC Sym posium , Tex t i le So lven t Techn ology , (Jan 1973) 91 .

18 Dow Chemica l Co . , USP 3 ,535 , 156 (11 Dec 1967) .

19 Go ddar , Me ll iand Texti lber . , 54 (July 1973) 742.

20 Fusconi , AAT CC Sym posium , Tex t i le So lven t Tech . , ( Jan 1973) 97.

21 Kn it t ing Tim es (Jan 1974) 20.

22 ICI , M ond Div is ion , Techn ica l Serv ice Note , T5/BS/126.

23 Ship m an, Tex ti lveredlu ng, 5 (1970) 523.

24 Kal inow ski , Am er . Dy estu f fR ep . , 61 (5) (1972) 31 .

25 J.V . Po ncelet , Text . J. Austral ia , 39 (Sept 1964) 30.

26 C .A . And erson, M . Lipson, J. F. Sinclair and F. G. W ood, Proc. of the 3rd Int .Wool Text . Res. Conf . , 3 (1965) 141.



Scour ing M achiner ies 159

27 Tex t . J. Au stral ia , 44 (1969) 34.

28 Bla nken burg and Breuea , M el l iand Tex t i lber . , 63 (1982) 515 .29 J . Park , A Prac t ica l In t roduc t ion to Yarn Dyeing , The Soc . o f Dye rs and

Colour is t s , Perk in House , Gra t ton Road , Bradford , West Yorksh i re (1984)

p 22.

30 J . T . M arsh , In t roduc t ion to Tex t i le Bleach ing , Cha pm an and Hal l, London ,

1956.

31 Si lk and Colours , S andoz Ltd . , Bas le , Sw i tzer land (1987) p 41 .



Chapter 6

B L E A C H I N G O F T E X T I L E S

6 . 1 I n t r o d u c t i o nTh e na tura l f ibre and fabr ics even a f te r scour ing s t il l conta in na tu ra l ly occu r ing

c o lou r ing m a t t e r . Th i s ye l lowish a nd b r own d i sc o lou r a t ion m a y be r e l a t e d to f l a -

vone p igm e n t s o f the c o t ton f lowe r . The c l im a te , so i l, d r ough t a nd f r os t c a n a l so

c a use va r iou s de g r e e s o f ye l lown e ss . T ips o f l e a ve s o r st a lk s c om ing in c on ta c t

w i t h t h e m o i s t b a l l a f t e r o p e n i n g w i l l c a u s e d a r k s p o t s a n d d i s c o l o u r a t i o n .

D isc o lou r a t ion m a y a l so c om e f r om d i r t , dus t , i n se c t s o r f r om ha r ve s t ing o r p r o -

c e s s ing e qu ip m e n t in the f o r m o f o i ls a nd g r e a se s . The ob je c t o f b l e a c h ing i s t o

p r odu c e w h i t e f a b r i cs by de s t r oy ing the c o lou r ing m a t t e r w i th the he lp o f b l e a c h ing

a ge n t s w i th m in im um de gr a da t ion o f the f ib r e. The b le a c h ing a ge n t s e i the r ox id i se

o r r e d u c e t h e c o l o u r i n g m a t t e r w h i c h i s w a s h e d o u t a n d w h i t e n e s s t h u s o b t a i n e d i s

o f pe r m a ne n t na tu r e . C he m ic a l b l e a c h ing o f te x t i le f ib r e s is f u rthe r a ide d by a dd i -

t ion o f op t i c a l b r igh te ne r s .

T h e p r i m i t i v e m e t h o d o f cl o th b l e a ch i n g , n a m e l y h a r s h s c o u r in g a n d e x p o s u r e

to the sun wa s a l so a c he m ic a l p r oc e s s in wh ic h l igh t s e rve d a s a n ox ida t ion c a t a -

ly st . How e ve r , t he p r oc e sse s a r e t im e c onsum a b le , l a bour in te ns ive , h igh ly va r i a b lein qua l i ty o f goods p r odu c e d , a nd t i e d up l a rge a m oun t o f c a p i ta l . The f i r s t m a jo r

b r e a k w i th t ra d i t iona l m e thod s o f b l e a c h in g c a m e in 17 56. N ine m a jo r b r e a k -

th r ou ghs in the f i e ld o f b l e a c h ing f l ax a nd c o t ton a r e show n in Ta b le 6 .1 . Dur ing

T A B L E 6.1

N i n e M a j o r B r e a k - t h r o u g h s i n B l e a c h i n g C e l l u lo s i c s

A p p r o x i m a t e D a t e o f S i g n i fi c a n t U s u g e

S u lphu r i c a c id S c ourC h l o r i n e B l e a c h

L e B l a n c P r o c e s s f o r S o d a A s h

H i g h P r e s s u r e K i e r

R o p e W a s h e r

E n z y m e D e s i z in g

P e r o x i d e B l e a c h i n g

C o n t i n u o u s P e r o x i d e B l e a c h i n g

F luor e sc e n t B r igh te ne r s

1756

1790

1791

1815

1830

1900

1925

1939

1950



Bleach ing o f Tex t i le s 161

the la ter s tage o f tw ente eth century the time requi red for b leaching dropped s teadily

f rom mo nths t o days to hours . Now -a-days , man pow er r equ i red fo r ave rage p l an t

i s decl ined con s iderab ly and the cos t of b leache d f in i shed prod uct i s a lso reduced.

This t echnical break- through wi l l cont inue in the fu ture a l so and wi l l reduce the

cos t of b leac hing fur ther.

A general classif ication o f bleaching agents is shown in Fig. 6-1. In 1790 Bertholet

B l e ach i n g A ge n t sI

I IOx i d a t i on B l e ach i n g Age n t s Re d u c t iv e B l e ach i n g Age n t s

I 1. Sulp hur diox ide

I I 2 . Sod ium hyd rosulph i te

P e r ox id e S ys t e m Ch l or in e S ys t e m 3. Sulphoxyla tes

1. Hyd roge n pe rox ide 1. B l each ing pow der 4 . Ac id i c sod ium su lph i te

2 . S od ium perox ide 2 . S od ium hypoch lo r i t e 5 . S od ium b i su lph i t e s

3 . S od ium perbora t e 3 . L i th ium hypoch lo r i t e

4. Potassium permanganate 4. Sod ium chlori te

5 . Peracet ic ac id 5 . Ch loram ine6. Other peracids 6 . I socynu al t r ich lor ide

Figure 6-1 . Class i f ica t ion o f b leach ing ag ents .

deve loped b l each ing p roces s u s ing w a te r so lu ti ons o f ch lo r ine . T ennan t i n 1978

deve loped so li d b l each ing pow der . Ch lo r ine based m ate r ia l s such as sod ium hy-

pochlor i te , ca lc ium hypochlor i te and sodium chlor i te , predominated unt i l the la te

1920s wh en peroxide cam e in to wide r use wi th the cheaper e lec t ro ly t ic synthes i s of

hydrogen peroxide . By 1940, about 65% and to-day about 90% of a l l co t ton i sb l eached wi th hydrogen pe rox ide .

6 .2 B leach ing wi th Hypoch lor i te s

Hy poc hlori tes as bleaching agents are s ti ll pop ular despi te the ant i -chlorine lobb y

and env i ronme n ta l p res su res . S om e o f t hese s a lt s wh ich a re used fo r the b l each ing

of tex t il es are br ief ly descr ibed .

6 .2 .1 Calc ium hypoch lor i te (B leach ing powder )

A solu tion of b leaching p ow der conta ins ca lc ium hypoc hlor i te [ C a ( O C 1 ) 2 . 4 H 2 0 ] ,

calc ium chlor ide [CaC12, Ca(OH)2.H20] , lime hyp och lorous ac id form ed by the



162 B l e a c h i n g o f T e x t i le s

hyd r o lys i s o f h yp oc h lo r i t e , po ss ib ly f r e e c h lo r ine a nd o the r so lub le im pur i t i e s li ke

c a lc ium c h lo ra t e , c a l c ium pe r m a nga n a te e t c. C a lc ium hyp oc h lo r i te i s ge ne r a l ly p re -pa r e d f r om b le a c h in g pow de r o r fr om l iqu id c h lo r ine a nd s l a ke d l im e suspe ns ion .

I t i s a l so poss ib l e to m a ke so lu t ions o f hyp oc h lo r i t e by pa s s ing c h lo r ine in to m i lk

o f li m e . S o l id b l e a c h i n g p o w d e r m a y b e o b t a in e d b y p a s s i n g c h l o r in e o v e r h y -

d r a t e d l im e [ 1 . In th is p r oc e ss c a r e m u s t be t a ke n no t t o inc r e a se the t e m pe r a tu r e

a bov e 55~ s inc e a t h ighe r t e m p e r a tu r e s , c h lo r a t e a nd c h lo r ide a r e f o r m e d .

B le a c h ing powde r i s pa r t i a l ly so lub le in wa te r . A sm oo th pa s t e w i th wa te r i s

f ir s t p r e pa r e d a nd the n d i lu t e d wi th w a te r. Th i s i s t he n a l lowe d to s t a nd un t il wh o le

o f the su spe n de d m a t t e r ha s s e t tl e d to bo t tom . T he c l e a r supe m a te n t l i qu id i s t he n

dr a in e d - o f f f o r u se wh ic h i s a bou t 12~ a nd c on ta ins a bou t 3 .9 % a va i l a b le c h lo -

r ine . This i s then d i lu ted to the requi re d s t rength .

C a l c i u m h y p o c h l o r i t e u n d e r g o e s r a p i d e x o t h e r m i c d e c o m p o s i t i o n o n h e a t i n g

a bov e 17 5~ B le a c h ing pow de r so lu t ion r e a c t s w i th a c ids w i th the e vo lua t ion o f

chlor ine .

Ca(OC1)2 + HC1 = CaC12 + 2HOC 1

Ca(OC1)2 + H2SO4 = C a S O4+ 2HOC 1CaC12 + H2SO4 = CaSO4 + 2HC1

2HOC1 + 2HC 1 = 2H 20 + 2C12

C e r t a i n m e t a l s o r t h e ir o x i d e s b r i n g a b o u t c a t a ly t ic d e c o m p o s i t io n o f b l ea c h i n g

pow de r . S im i l a r r e a c t ion c a n a l so oc c u r w i th o the r m e ta l s suc h a s i ron o r c oppe r .

C a (OC 1)2 + 4 C o 0 = 2 C o 0 3 + C aC 12

2C oO 3 = 4 C o O + 0 2

Th e ox id i s ing a c t ion o f c a l c ium hy poc h lo r i t e is due to hyp oc h lo r ous a c id . The

c ond i t ions ( pH) wh ic h f a vo ur the f o r m a t ion o f hyp oc h lo r o us a c id inc r e a se the

o x i d i s in g p o w e r o f b l e a c h i n g p o w d e r . F r e s h l y p r e p a re d c a l ci u m h y p o c h l o r i t e s o l u -

t ion ha s a pH o f a bou t 11 .0 5 wh ic h on s t a nd ing o r a g i ta t ion re duc e s the a lka l in i ty

by p r e c ip i t a t ing in so lub le c a r bo na te a nd thus inc r e a s ing the c onc e n t r a t ion o f hy -

poc h lo r ous a c id . Th i s a c id i c hypoc h lo r ous a c id i s m or e powe r f u l b l e a c h ing a ge n t

tha n the a lka l ine hy poc h lo r i t e a nd a r e no t s a f e a s th i s c a use s de g r a da t ion o f the

c e l lu los i c m a te r i a l due to the f o r m a t ion o f oxyc e l lu lose .

6 .2 .2 S o d i u m h y p o c h l o r i t eS o d ium hyp oc h lo r i t e is a sod ium sa l t o f hyp oc h lo r o us a c id (HOC 1). S od ium

hypoc h lo r i t e c a n be p r e pa r e d by pa s s ing c h lo r ine ga s in to a t a nk c on ta in ing p r e -



B l e a c h i n g o f T e x t i le s 163

p a r e d s o l u ti o n o f c a u s ti c s o d a , s o d i u m c a r b o n a te o r m i x t u re o f t h e tw o ( a b o u t 4 %

b y w e ig h t ) a t ab o u t 2 7~

2 N aO H + C12 = N aOC1 + N aC1 + H2 0 + 2 5 C a l

6N aO H + 3 C12 = N aC1 + N aC1 03 + 3 H 2 0

An o th e r w ay o f p r ep a r in g s o d iu m h y p o c h lo r i t e s o lu t i o n is b y t h e e l ec t ro ly s i s o f

a s o lu t i o n o f s o d iu m ch lo r id e . In t h i s m e th o d s o d iu m h y d r o x id e i s f o r m ed a t t h e

ca th o d e an d ch lo r in e a t t h e an o d e o n p as s in g e l ec t r i c cu r r en t t h r o u g h th i s s o lu t io n .

T h e s o d iu m io n r eac t s w i th w a te r to f o r m s o d iu m h y d r o x id e an d t h e l ib e r a t ed ch lo -

r in e r e a c t s w i t h s o d i u m h y d r o x i d e f o r m i n g s o d i u m h y p o c h l o r it e .

N a + e - -~ N a

2 N a + 2 H 2 0 --~ 2 N a O H + H 2 0

2C1 ~ C12 + 2e

2 N aO H + C12 ~ N aOC1 + N aC 1 + H2 0

So d iu m h y p o ch lo r i t e s o lu t i o n i s s t r o n g ly a lk a l i n e (p H ~ 1 1 . 5 5 ) an d t h e f r ee

cau s t i c p r e s en t i n t h e s o lu t i o n ac t s a s a s tab i l is e r . So d a - as h s cav a n g es f ree h y d r o -

ch lo r i c ac id f o r m in g a n o n - v o l a t i l e s a l t an d m a in t a in i ts a lk a l in i t y . S t ab i l it y o f s o -

d iu m h y p o ch lo r i t e s o lu t i o n i s a l s o im p r o v ed b y s to r in g i t i n a d a r k r o o m b e lo w3 0~ an d fr ee f r o m co n tam in a t io n s o f an y h eav y m e ta l sa l ts . T h e d eco m p o s i t i o n o f

s o d i u m h y p o c h l o r i t e c a n b e re p r e s e n t e d b y t h e f o l l o w i n g r e a c t io n s :

2NaO C1 --~ NaC1 + N aC102

or 2NaO C1 -~ 2NaC1 + 02 1"

or 3NaOC 1 --~ 2NaC1 + NaC 103

T h e b l e a c h i n g m e c h a n i s m o f so d i u m h y p o c h l o r i te c o n s i st s o f t h e f o ll o w i n g

r e a c t i o n [ 2 ] :

N aOC1 - + N aC1 + (O)

T h e a b o v e r e a c t i o n i s a c c o m p a n i e d b y s e v e r a n c e o f g lu c o s e l i n k a g e i n c o tt o n ,

r e s u l t i n g i n l o s s o f t en s i le s t r en g th .

6 .2 .3 L i t h i u m h y p o c h l o r it e a n d c h l o r in a t e d t r i s o d i u m p h o s p h a t e

L i t h i u m h y p o c h l o r i t e c a n b e o b t a i n e d b y m i x i n g s t r o n g s o l u t i o n s o f s o d i u m

h y p o ch lo r i t e w i th l i t h iu m ch lo r id e . T h i s r e s u l t s i n p a r t i a l p r ec ip i t a t i o n o f s o d iu m

ch lo r id e . T h e p r o d u c t o b t a in ed b y ev ap o r a t i o n o f s u p e r n a t en t s o lu t i o n t y p i ca l l y

co n ta in s 3 0% l i t h iu m h y p o ch lo r i t e (L iOC1 ) , 3 4 % s o d iu m ch lo r id e an d o th e r s a lt s.C h l o r i n a t e d t r i so d i u m p h o s p h a t e i s a h y d r a t e d c o m p l e x h a v i n g c h e m i c a l f o r m u l a

(N a 3 P O4 . H2 0) N aOC1 an d co n t a in s a p p r o x im a te ly 4 % av a i l ab l e ch lo r in e . G en e r -



164 B l e a c h i ng o f Te x t i l e s

a l ly , t he y a r e m a i n l y us e d a s la undry de t e rge n t s , be c a us e s od i um a nd l i th i um do no t

prec ip i t a te an ionic sur fac tant s as the ca lc ium sa l t s .6 .2 . 4 F a c t o r s e f f e c t in g i n h y p o e h l o r i t e b l e a c h i n g o p e r a t i o n s

C o t t o n c a n b e b l e a c h e d w i t h h y p o c h l o r i t e s o l u t i o n a t r o o m t e m p e r a t u r e c o n -

ta in in g 1-3 g ava i l ab le ch lor ine p er l it re a t pH ran ge o f 9 .5 to 11 . Th e pH i s m ain-

t a i ne d by a dd i ng 5 g / 1 s od i um c a rbona t e i n t he b l e a c h ba t h . A f t e r b l e a c h i ng t he

c lo th i s t rea ted w i th d i lu te hydroc hlor ic ac id to neut ra l i se any a lka l i ( sour ing) present

i n t he c l o th . A n a n t i c h l o r t r e a t me n t w i t h s od i um t h i os u l pha t e o r b i s u l ph i t e i s a l so

r e c omme nde d t o r e move a ny r e s i dua l c h l o r i ne f rom t he c l o t h . F i na l l y , t he c l o t h i s

w a s h e d w i t h w a t e r t o r i n s e ou t a c id f rom t he c lo t h .

2N a O C 1 + H z S O 4 ~ N a z S O 4 + 2H O C 1

2HOC1 - -~ 2HC1 + 20

HOC 1 + HCI~-~-C12 + 2H 20

6 .2 .4 .1 Ef fec t o f p H

H y poc h l o r i t e i on i s e s d i f f e r e n t l y unde r d i f f e r e n t pH c ond i t i ons a n d a c ti ve c om-

po ne nt can be e f fec t ive in three d i f fe ren t s t a tes (F ig . 6 -2) . In the regio n of pH 7 ,

! i '

9 . ! ~

...... A ci d l A lk ali ne //a ~

I "

[ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

p H o f s o l u ti o n

F i gure 6 -2 . R a t e o f ox i da t i on o f c e l lu l os e i n t e rms o f the

c ons u m pt i on o f ha l f the t o t al a va i l a b l e c h l o r i ne .

w h e n h y p o c h l o r o u s a c i d a n d h y p o c h l o r i t e i o n a r e p r e s e n t a p p r o x i m a t e t h e s a m e



Bleac h in g o f T ex t i l e s 165

co n cen t r a t i o n s , t h e r a t e o f a t t ack o n ce l l u lo s e i s g r ea t l y en h an ced . In t h e ca s e o f

b l each in g p o w d er t h e p H h as f a ll en to w i th in th e d an g e r zo n e a f t e r 1 5 m in an d a f t e r

l h w h en s o d iu m h y p o ch lo r i t e i s u s ed . As t h e p H f a ll s b e lo w 5 , t h e l i b e r a ti o n o f

c h l o r in e b e g i n s t o t a k e p la c e a n d p H b e l o w 1 . 5 , t h e w h o l e o f h y p o c h l o r o u s a c i d is

co n v e r t ed i n to ch lo r in e . In t h e p H r an g e 9 t o 1 1 , a p l a t eu o ccu r s a t w h ich l i t t l e

ch an g e o ccu r s an d i s t h e n o r m a l u s e r an g e f o r b l each in g w i th h y p o ch lo r i t e s o lu -

t io n . T h e ac t i v e s p ec i e s [ 4] ap p ea r t o b e OC1 - i o n, o r a co m p lex o f HOC1 an d

OC1- . The pH (8 .5 -11 .0) i s s tab i l i sed by the a dd i t ion o f buf fe r s (5 g /1Na2CO3).

H O C1 ~ - H § + O C 1 -

H O C I + H § C 1 2 +H 2 06 .2 . 4. 2 E f f e c t o f t e m p e r a t u r e

Gen er a l l y b l each in g o f co t to n i s ca r ri ed o u t w i th 1 .5 g/1 o f h y p o c h lo r i t e s o lu ti o n

a t ab o u t 4 0~ f o r 1 h . H ig h e r t em p er a tu r e i n c r eas es t h e ra t e o f b l eac h in g b u t a t t h e

s am e t im e d eg r ad a t i o n o f co t t o n is a l s o i n c r eas ed . Hy p o ch lo r i t e s o lu t io n s b y

th em s e lv es a r e q u i te s t ab l e a t t h e b o i l a t p H v a lu es 11 o r h ig h e r , b u t d eco m p o s es a t

l o w er p H v a lu es [ 5 ] . Du r in g t h e d eco m p o s i t i o n o f h y p o ch lo r i t e s o lu t i o n s , ch lo r a t e

f o r m a t io n p r ed o m in a t e s i n t h e ab s en ce o f co tt o n , w h i l e i n t h e p r e s en ce o f co tt o n , i t

i s p r ac t i ca l l y ab s en t u n d e r a lk a l i n e co n d i t i o n [6 ] . Hy p o ch lo r i t e s o lu ti o n s i f b u f f e r ed

to p H 1 1 , t h e r a te o f b l eac h in g i s i n c r eas ed b y a f ac to r o f 2 .3 t im e s f o r ev e r y 1 0~

r i se in tem pera tu re . I t i s thus , poss ib le to b leach a t 60~ in 7 m in , bu t i s d i f f icu l t to

co n t r o l t h e d eg r ad a t i o n o f co t to n i n s u ch s h o r t p e r io d o f b l each in g .

6 .2 . 4. 3 E f f e c t o f c o n c e n t r a t i o n

T h e c o m m e r c i a l s o l u t io n o f s o d iu m h y p o c h l o r i te c o n t a in s 1 4 - 1 5 % a v a i l a b le

ch lo r in e , co m p ar ed t o 3 5 - 3 6% in b l each in g p o w d er . T h e co n cen t r a ti o n o f h y p o c h lo -

r i te i n t h e b l each in g b a th g en e r a l l y v a r i e s f r o m 1 t o 3 g/1 av a i l ab l e ch lo r in e . T h eo p t i m u m b l e a c h i n g c o n d i ti o n s , h o w e v e r , d e p e n d o n th e d e g r e e o f d i sc o l o u r a ti o n

o f t h e c lo th an d t h u s t h e tem p er a tu r e an d t im e o f r eac t i o n s h o u ld b e ad ju s t ed ac -

co r d in g t o t h e r eq u i r em en t . T h e co n cen t r a t io n o f h y p o ch lo r i t e s o lu t io n i s n o r m a l ly

es t im a ted b y m ean s o f s t an d a r d t h io s u lp h a t e o r a r s en i te t i t ra t io n .

6 . 2 .4 . 4 E f f e c t o f e le c t r o l y t e

T h e ad d i t i o n o f s a l t i n t h e h y p o ch lo r i t e b l each in g b a th i n c r eas es t h e ac t i v i ty i n

th e i n i ti a l p e r io d d u e t o th e p r o d u c t io n o f n as ce n t ch lo r in e . T h e ad d i t i o n o f ch lo -

r ide moves the equ i l ib r ium to the le f t -hand s ide , bu t a f te r , say 15 r a in , when the




n ew eq u i l i b r iu m i s r each ed , t h e s u d d en s t im u la t ed e f f ec t i s ceas ed an d b l each in g

r es u m es i t s n o r m a l co u r s e an d h en ce ac t i o n o f s a l t i s o n ly tem p o r a r y an d co n f in edto t h e f i rs t s t ag e o f b l each in g .

2Ca(OH )2 + 2C12 ~ Ca(OC1) 2 + CaC12 + 2H 20

H O C 1 + N a C 1 = 2 C 1 + N a O H

6 . 2 . 5 A c c e l e r a t e d h y p o c h l o r i t e b l e a c h i n g

T h e a im o f acce l e r a ted b l each in g i s t o ad o p t a co n t in u o u s b l each in g b y r ed u c in g

th e b l eac h in g t im e an d ch lo r in e co n s u m p t io n w i th t h e h e lp o f m o r e r eac t i v e b l each

l iq u o r . H o w e v e r , t h e a c c e l e r a te d b l e a c h i n g m a y l e a d to d e g r a d a t io n a n d y e l l o w i n g

of the co t ton f abr ic .

6 .2 .5 .1 A c c e l e r a t e d b l e a c h i n g i n t h e d a n g e r z o n e

Blea ch in g w i th h y p o ch lo r i t e s o lu t io n c o n t a in in g 1 g/1 o f av a i lab l e ch lo r in e w i th

th e ad d i t i o n o f 5 g/1 s o d iu m ca r b o n a t e a t p H c lo s e t o 7 can b e d o n e i n j u s t 1 0 m in .

T h e s y s t em i s m o r e r eac t i v e i n t h e d an g e r zo n e an d th u s b l each in g can b e d o n e i n a

s h o r t e r t im e .

6 . 2. 5 .2 A c c e l e r a t e d b l e a c h i n g i n c o n j u n c t i o n w i t h H ~ O 2

H y p o c h l o r i t e b l e a c h i n g c a n b e a c c e l e r a t e d b y t h e a d d i ti o n o f h y d r o g e n p e r o x -id e , am m o n ia , ch lo r am in e e t c . [7 , 8 ]. Hy d r o g en p e r o x id e r eac t s w i th h y p o ch lo r i t e

f o r m in g h y d r o x y l an d H O 2" r ad i ca l s . T h e h y d r o x y l r ad i ca l m ay r eac t a s b e f o r e o r

H 2 0 2 + C 1 0 - - > H O 2 + C I ' + O H

H O 2" + O H--> H 2 0 + O 2

t e r m in a t e b y r ea c t i o n w i th HO2 " . In ac tu a l p r ac t i ce f ab ri c i s f ir s t t r ea t ed w i th co ld

a lk a l i n e h y p o ch o r i t e s o lu t i o n a s a p r e - b l eac h in g ag en t an d t h en an a f te r b l each i s

ca r r ied o u t (w i th o u t r in s in g ) i n co n ju n c t io n w i th h y d r o g e n p e r o x id e o r s o d iu m ch lo -

r i t e [9 ] . T h e co ld h y p o ch lo r i t e t r ea tm en t can b e ca r r i ed o u t i n a J - Bo x ty p e co ld

r eac t i o n ch am b er o f 7 r a in reac t i o n t im e . T h e c lo th t h en p as s es i n an o th e r h o t r eac -

t i o n J - Bo x in o p en w id th f o r m an d p l a i t ed i n to a b ig g e r p i l e w i th o u t an y s e r io u s

r i s k o f c r eas in g an d p o s s ib l e c r eas e m ar k in g . T h e ad v an t ag es o f t h i s p r o ces s a r e

th a t t h e t o ta l r eac t i o n t im e o f t h e b l each in g p r o ces s can b e r ed u ced , H2 02 ac t s a s an

an t ich lor and f abr ics con ta in ing co t ton / rayon m ix ture as wel l as co lour -w oven goods

can b e b l each e d d u e t o m i ld e r co n d i t io n s em p lo y e d i n t h e h y p o ch lo r i t e s t ag e .

6 .2 . 5. 3 A c c e l e r a t e d b l e a c h i n g a t e l e v a te d t e m p e r a t u r e

An o th e r p o s s ib l e w ay to r ed u ce t h e b l each in g t im e i s t o w o r k a t e lev a t ed t e rn -



Bl each i n g o f T ex t i le s 167

p e ra t u re [ 5 , 1 0] . Rap i d b l each i n g m ay b e d o n e a t 60 -80~ co n t a i n i n g 0 .9-1 .6% o f

ac t ive c h lor ine (o .w.f . ) in the pH rang e o f 8 .6 to 12 .8 .6 .2 .5 .4 Acce le ra t ed b leach ing in pre sence o f add i t ive s

So m et i mes b ro m i d es o r r e la t ed co m p o u n d s a r e ad d ed to th e h y p o ch l o r i t e l i q u o r

t o acce l e r a t e t h e b l each i n g ac ti o n . I t is l ik e l y t h a t s o d i u m h y p o b ro m i t e i s fo rme d

w h i ch i s a s t ro n g e r o x i d i s i n g ag en t t h an h y p o ch l o r i t e .

M e t h o d s o f b l each i n g a t h i g h t emp e ra t u re an d p H c l o s e to 7 in p re s en ce o f

su l fam ic a c id in hypo ch lor i t e b leach ing of co t ton has been sugge s ted [ 11 ] . I t has a

s t ab i li s in g e f f ec t, s l o w i n g t h e r a te o f d eco m p o s i t i o n o fh y p o c h l o r i t e an d r ed u c i n g

the damage to the f ib re , wi thou t hav ing any adverse e f fec t on the f ina l whi teness .

6 . 2. 5. 5 A c c e l e r a t e d b l e a c h i n g b y s t e a m i n g

An acce lera ted me thod fo r b leach ing po lyes te r /co t ton b lended fabr ic i s descr ibed

[12] . The p roc ess cons i s t s o f s t eam ing a t 100 +15~ fo r 60 ra in fo l low ed by wa sh-

ing and padding th rough a so lu t ion con ta in ing 10-12 g /1 ac t ive ch lor ine a t 25~

The fabr ic i s then age d in a se r i es o f cham bers fo r 60 m in and then l ed th rough an

ac id i fy ing ba th wi th 2 -2 .5 g/1 su lphur ic ac id a t 20~ The acc e lera ted e f fec t is

ach i ev ed b y ch an g i n g t h e o rd e r o f t he o p e ra t i o n s.6 .2 .6 A d v a n t a g e s o f s o d i u m h y p o c h l o r i te b l e a c h i n g o v e r b l e a c h i n g p o w d e r

So d i u m h y p o c h l o r i t e h a s p rac t i ca l ly r ep l aced b l each i n g p o w d er d u e t o it s v a r i -

o u s ad v an t ag es a l t h o u g h s o l u ti o n s o f h y p o ch l o r i te a r e mo re ex p en s i v e t h an ca l -

c i u m h y p o ch l o r i t e .

(i) B l each i n g p o w d er is a m i x t u re o f ca l c i u m h y p o ch l o r i t e w i t h l ime . T h u s,

ca lc ium carbonate se t t l es on the f ib re dur ing b leach ing process . On the

co n t r a ry , s o d i u m h y p o ch l o r i t e i s fr ee f ro m an y s u ch d an g e r o f sp eck s o f

l i me b e i n g d ep o s i t ed o n t h e c l o th .

( ii ) Ble ach ing pow de r is par t i a l ly so lub le in wa ter and ex i s t s in a so l id fo rm.

H o w ev e r , s o d i u m h y p o ch l o r i t e , b e i n g a s o d iu m s a l t o fh y p o c h l o ro u s ac id ,

d o es n o t r eq u i r e an y d i s s o l v in g a r r an g e m en t an d a r e r ead y fo r i mm ed i a t e

use . Hypochlor i t es a re easy to hand le .

( ii i) Ch l o r i n a t ed l i me r eq u i re s h i g h e r a l k a l i n it y th an t h a t o f s o d i u m h y p o ch l o -

r i t e so lu t ions fo r ac t ive b leach ing condi t ions .

( iv ) So d ium h ypo chlor i t e so lu t ions have l ess t ende ncy fo r the pH va lue to fa l ld u r i n g b l each i n g . Cau s t i c s o d a i s l i b e ra t ed b y t h e h y d ro l y s i s o f s o d i u m



168 B le a c h ing o f Te x t il e s

hypoc h to r i t e f o r m sod ium c a r bona te unde r the a c t ion o f c a r bon d iox ide

f r om a tm osphe r e . S od ium c a r bona te thus f o r m e d c a n be e a s i ly wa she da w a y w i th wa te r a nd re duc e s a c id re qu i r e m e n t f o r sou r ing . I n suc h c a se ,

su lphur i c a c id m a y be use d a s sou r ing a ge n t in p l a c e o f the m or e c os t ly

hydrochlor ic ac id .

(v) Sod ium hypo chlor i te can pene t ra te in to the fabr ic mo re thoro ugh ly than in

the c a se o f b l e a c h ing pow de r a nd the r e fo r e sho r t er t im e o f b l e a c h ing i s

poss ib l e in the c a se o f sod ium hypoc h lo r i t e .

6 .2 . 7 D i s a d v a n t a g e s o f s o d i u m h y p o c h l o r i te

(i) S od ium hypo c h lo r i t e doe s no t p r oduc e c om ple te ly sa t i s f a c to r y wh i t e s

insp i te o f m a ny a dva n ta ge s .

( ii ) B le a c h ing wi th sod ium hypoc h lo r i t e p r oduc e s s l igh t da m a ge to c e l lu los i c

f ibres.

( ii i) S od ium h ypoc h lo r i t e c a n no t be use d fo r the b l e a c h ing o f syn the t ic f ib r e s

as it p rod uces grea te r dam age to such f ibres .

( iv ) B le a c h ing wi th sod ium hypoc h lo r i t e so lu t ion r e qu i r es c o r r os ion r e s i s ta n t

e qu ipm e n t .( v) S od ium hypoc h lo r i te p r oduc e s unp le ase n t odour s in wor k ing e nv i ronm e n t .

(v i) So diu m hypo chlor i te so lu t ion is ha rm ful to sk in in conce nt ra ted form.

(v ii ) I t p rod uces ha rsh hand le on fabr ic . Fur the rm ore , i t canno t be used on na tu-

ra l an im al f ibres .

(v ii i ) S tabi l i sa t ion of sodium hyp och lor i te i s d i f ficu l t to achieve w here pH var -

ies.

( ix ) The f o r m a t ion o f h igh ly tox ic c h lo r ina te d o r ga n ic b ip r oduc t s ( A O X ) du r -

ing the b l e a c h ing p r oc e ss ha s l im i t e d i t s u se be c a use the se c om poun ds a re

a p o t e n t i a l h a z a r d t o t h e d r i n k i n g w a t e r r e s o u r c e s w h e n d i s c h a r g e d

[13, 14].

6 .3 B l e a c h i n g w i t h P e r o x id e

Hy dro gen p eroxid e was d iscovered in 1818 and it s use in b leach ing tex t i le s was

f i r s t sugges ted in 1866 . However , i t s h igh cos t l imi ted i t s use in co t ton b leaching

un t il 1935 . The p r ob le m wa s pa r t i a lly so lve d by the p r oc e ss u s ing ba r ium p e r ox ide

a nd phospho r i c a c id . In 19 26 hyd r oge n pe r ox ide w a s m a nu f a c tu r e d by a n e l e c tr o -ly t i c p r oc e ss ba s e d on the de c o m p os i t ion o f pe r su lph ur i c a c id (H2SOs) [15 ] .



B le a c h ing o f Te x t i l e s 169

Sulphu r ic ac id is f ir s t ionised in to hyd roge n and b isu lpha te ions wh ich i s d ischarg ed

on the a node a nd the n f o r m pe r su lphur i c a c id , wh ic h on va c uu m d i s t i ll a t ion r e ac t swi th wa te r t o f o r m hydr o ge n pe r ox ide . Hy dr oge n pe r ox ide c a n a l so be ob ta ine d by

d i s so lv ing sod ium pe r ox ide in wa te r . In s t e a d o f d i s so lv ing the pe r ox ide a nd the n

neutra l i s ing the l ibe ra ted a lka l i , the pe roxide can s lowly be s t i r red in to s l ight ex-

cess of su lphur ic ac id . The reac t ion i s ca re fu l ly cont ro l led as a la rge am ou nt o f hea t

i s e vo lve d . F o r e ve r y 100 lb o f H20 2 ( 40 % by vo lum e ) 9 5 lb o f Na 2 0 2 i s t o be use d .

H2804 ~ H+ + HSO4-

2HS O2- -2e ~ 2HSO 4

2H SO 4 --+ H2S208

H2820 8 + H2O ----> H2SO s + H2SO 4

HzSO 5 + H2O ~ H2SO 4 + H2O 2

Na 20 2 + 2H20 = 2Na OH + H20 2

Na202 + HzSO 4 = Na2SO 4 + H202

Pur e hy dr og e n p e r ox ide i s f a i rly s t ab le in p r e se nc e o f su lphur ic a c id a nd phos -

phor i c a c id i f s to r e d a wa y f r om sun l igh t i n a pe r f e c t ly sm o o th bo t t le . I n a lka l ine

m e d iu m i t i s le s s s t a b le a nd e ve n t r a c e s o f alka li ( Na OH , Na 2C O3) de c om posea que o us so lu t ion o f hyd r oge n pe r ox ide . The a dd i t ion o f a l c oho l , g lyc e r ine o r

be r b i tu r i c a c id a l so s t a b i l i s e hydr oge n pe r ox ide . Hydr oge n pe r ox ide a l so de c om -

pose s in the p r e se nc e o f fine ly d iv ide d he a vy m e ta l s suc h a s coppe r , i r on , m a nga -

ne se , n i c ke l , c h r o m ium e tc . o r t he i r ox ide s w i th l ibe r a t ion o f oxyge n .

2H202 ~ 2H20 + O 2

The vo lum e s t r e ng th o f hyd r oge n p e r ox ide i s e xp r e s se d a s the vo lum e o f l i ber -

a t e d oxyge n a t N .T .P . on he a t ing one vo lum e o f hydr og e n pe r ox ide sa m ple . Hydr o -

gen pe roxide i s genera l ly made of 10 , 12 , 20 , 100 and 130 volume s t rength . A 10

vo lum e pe r ox ide so lu t ion i s one wh ic h wi l l l i be r a t e 10 t im e s i t s own vo lum e o f

oxyg e n . Th e pe r c e n ta ge c onc e n t r a t ion i s e xp r e s se d a s the qua n t i ty o f pu r e hydr o -

ge n pe r ox ide in 10 0 pa r t s o f s a m ple a nd i s e xp r e s se d a s x%, y% e tc . The c om m e r -

c i al supp ly o f hyd r oge n p e r ox ide a r e ge ne r a l ly 35% a nd 50 %. A 10 vo lu m e hydr o -

ge n pe r ox ide c on ta ins 3% hydr oge n pe r ox ide a nd thus , 1% H20 2 = 3 .3 vo lum e

c onc e n t r a t ion . The s t r e ng th o f the a va i la b le o xyg e n c a n be e s t im a te d by t i t ra t ing

the pe r ox ide us ing s t a nda r d i se d po ta s s ium pe r m a nga na te ( KM nO 4) un t i l o r f a in tpe r m a ne n t p ink c o lou r a ppe a rs . How e ve r , i od ine m e thod i s p r e f e r r e d to pe r m a nga -

na te m e thod .




6 .3 .1 M e c h a n i s m o f p e r o x id e b l e a c h i n g

Th oug h hyd r oge n pe r ox ide i s s t a b le in a c id ic m e d ium , bu t b l e a c h ing oc c u r s bythe a dd i t ion o f a lka l i o r by inc r e a se d t e m pe r a tu r e . Hydr oge n pe r ox ide l i be r a t e s

pe r h ydr o xy l ion (HO2- ) in a que ous m e d iu m a nd c he m ic a l ly be ha ve s l ike a we a k

d iba s i c a c id . The pe r h ydr ox y l i s h igh ly un s t a b le a nd in the p r e se nc e o f ox id i sa b le

subs ta nc e ( c o lou r e d im pur i t i e s in c o t ton ) , i t i s de c om pose d a nd thus b l e a c h ing a c -

t ion t a ke s p l a c e . S od ium hydr ox ide a c t iva te s hyd r oge n pe r ox ide be c a use H § ion is

neu t ra l i sed by a lka l i which i s f avou rable for libe ra t ion o f r iO2-.

H202 ~ H + + H O 2-

H2 02 __~ H + + H O 2- OH- > H O 2- + H 20

Ho w eve r , a t h igh er pH (abo ve 10 .8 ) the libe ra t ion of HO 2- ion is so rapid th at i t

b e c o m e s u n s t a b le w i t h th e f o r m a t i o n o f o x y g e n g a s w h i c h h a s n o b l ea c h i n g p r o p -

e r ty . I f t he r a te o f de c om pos i t ion i s ve r y h igh , t he unu t i l is e d HO 2-m a y d a m a g e t h e

f ibre . A sa fe and opt im um p H for co t ton b leac hing l ie s be tw een 10 .5 to 10 .8 where

the r a te o f e vo lu t ion o f pe r hyd r oxy l ion i s e qua l t o the r a t e o f c onsu m p t ion ( fo r

b le a c h ing) . A t h ighe r pH, hydr o ge n p e r ox ide i s no t s t a b le a nd he nc e a s ta b i l is e r i s

f r e que n t ly a dde d in the b l e a c h ing ba th .

6 .3 .2 S t a b i l i se r s f o r p e r o x i d e b l e a c h i n g

The p r oc e ss o f r e gu la t ion o r c on t ro l o f p e r hy dr ox y l ion to p r e ve n t r a p id de c om -

pos i t ion o f b l e a c h a nd to m in im ise f ib re de g r a da t ion i s de sc r ibe d a s s ta b i l is a t ion .

S tabi l i se r s for pe rox ide no rm al ly func t ion by co nt ro l l ing the format ion o f f ree radi -

c a ls . The se a r e c om ple x b le nds o f a s el e c tion o f m a te r i a l s s e r v ing a num be r o f

f unc t ions . T he y c o u ld inc lude a ny o f the f o l lowing"

- A l k a l i , e .g . caus t ic sod a /ca rbona te / s i l ica te .- Dispersant , e .g . ac ry la tes /phosphona tes .

- S e que s t ra n t s , e .g . ED TAf l ) TPA/he p ton a te s /g luc ona te s .

- I no r ga n ic s , e .g . m a gn e s iu m sa lt s.

- C o l lo id s t a b i l i s e r s , e . g . a c r y l i c po lym e r s .

The se l e c t ion o f a lka l i t o be use d in pe r ox ide b l e a c h ing i s de pe nde n t on the

f ib r e s o r b l e nds be ing b le a c he d . S od ium hydr ox ide , sod ium c a r bona te a r e ge ne r -

a l ly used on ce l lu los ic f ibres whi ls t amm onia and va r ious phosp ha tes a re used when

b le a c h ing p r o te in f ib r es . Of the va r ious phospha te s on ly t e t r a sod ium pyr op hos -

pha te , Na4P207 a nd he xa m e ta p hosp ha te s a re o f i n te r e s t a s s ta b i l is e r s in a lka l ine

b le a c h b a th .





172 B le a c h ing o f Te x t i l es

no t c on ta in m a gne s ium sa lt s, t he th r ee m a in type s be ing the a m inopo lyc a r boxy la t e ,

p r o te in d e g r a da t ion p r od uc t s a nd se l e c te d su r f a c t an t s . The p r e f e r re d se que s t e r inga ge n t s in t e rm s o f bo th se que s t e r ib i l it y a nd s t a b i l it y to ox ida t ion a r e d i e thy le ne

t r i a m ine pe n ta a c e t i c a c id (DTPA ) , e i the r a s sod ium o r m a gn e s ium sa lt , and i ts hy -

d r oxy d e r iva t ive s . A m in opo lyc a r bo xy l i c a c ids u se d in the fo r m o f the i r m a gne -

s ium a nd c a l c ium sa lt s ha ve the a dva n ta ge ove r c onve n t iona l a m ino po lyc a r boxy l i c

a c ids in tha t t he y a r e no t r e duc e d to a m ino ox ide s a t h igh t e m p e r a tu r e a nd thus do

no t loose the i r s e que s t e r ing powe r . Po lyc a r bo xy l i c a c ids a c t m a in ly a s d i spe r s ing

ion - e xc h a nge r s . Phosph ona te s h a ve l im i t e d a pp l i c a tion a nd s inc e r e c e n t ly , due to

the i r eu t r i f ica t ion na ture , a re not pre fe r red . Phosphona tes a re ac t ive as complex

f o r m e r s w i th good d i spe r s ing p r ope rt i e s .

In recent yea rs ac ry la tes have been used in pre fe rence to phosp hona tes and whi ls t

he p tona te s a nd g luc ona te s ha ve r e p la c e d EDTA a nd DTPA. Ac r y l i c a c id c opo ly -

m e r s a r e no r m a l ly no t b iode g r a da b le . A m e thod ha s be e n pa te n te d to in tr oduc e

suga r m o le c u le s d i r e c tly in the po ly m e r c ha in o f po lyc a r bo xy l i c a c id [18] . The

suga r m o le c u le in the ta u tom e r ic e nd io l f o r m ha s C = C doub le bond wh ic h i s ne c e s -

sa r y f o r c opo lym e r i sa t ion wi th a c r y l i c a cid . S uga r po lya c r y la te s , how e ve r , due tothe hydr ox y l g r oups o f suga r, ha ve a b ind ing c a pa c i ty f o r fe r ri c ion . O the r b iode -

g r a da b le c om pou nds ( s ta b i l is e r s ) a re p r e pa r e d by g r a f t c opo lym e r i sa t ion o f a va i l-

ab le unsa tura ted m ono m ers such as male ic ac id , v inyl aceta te , me tha l ly l su lphona tes ,

m e t h o x y P E G , m e t h a c r y la t e a n d s a c c h a r o se a n d h av e a m o l e c u l ar w e i g h t r a n g e o f

3-20 thousa nd. Th ey can be used in the form of f ree ac id or the i r sa lt s . The b indin g

p o w e r o f c a l c iu m a n d m a g n e s i u m s a lt is 3 -5 t i m e s t ha t o f h o m o p o l y a c r y l a t e s , p a r -

t i c u la r ly f o r hydr ox ide s o f i r on , c a l c ium a nd m a gne s ium a t r oom te m pe r a tu r e a s

we l l a s a t bo i l . The y ha ve h igh d i spe r s ing powe r f o r i r on ox ide s , o f t he l e ve l o f

phosphona te s .

6 .3 .3 P a r a m e t e r s i n p e r o x i d e b l e a c h i n g o p e r a t i o n s

I t i s ve r y d i f f ic u l t t o spe c i f y s t r ic t gu ide l ine s f o r op t im u m b le a c h ing c ond i t ions

f o r hyd r oge n pe r ox ide a s the ope r a t ion i s no r m a l ly a f f e c t e d by the na tu r e a nd qua l -

i ty o f t he goods to be b l e a c he d , t he a m oun t o f b l e a c h ing r e qu i r e d a nd on the e qu ip -

m e n t a va i l a b le . How e ve r , t he f o l lowing ge ne r a l va r ia b le s a r e c ons ide r e d to be im -

p o r t a n t :

6 .3 .3 .1 Ef fe c t o f pH

The s t a b i l it y o f hyd r oge n pe r ox ide de pe nds on pH. A t pH 1 to 3 it is s t a b le ; bu t




a t h igh ly a lka l ine pH 11 .5 to 13 i t ha s l e a s t s t a b il it y . The b le a c h ing t a ke s p l a c e

a r o u n d 1 0 . 5 d u e t o a c c u m u l a t i o n o f p e r h y d r o x y l i o n s in t h e b l e a c h i n g b a t h . A tn e u t r al o r w e a k a l k al in e m e d i a , h y d r o g e n p e r o x i d e d o e s n o t p ro d u c e a n y w h i t e n i n g

e f f e c t a nd m a y c a u se de g r a da t ion o f c e l lu lose .

6 . 3 .3 . 2 E f f e c t o f t e m p e r a t u r e

I n p r a c t i c e c o t ton b le a c h ing wi th hyd r oge n pe r ox ide i s c a r ri e d ou t a t 90 - 100 ~

b u t th e t e m p e r a t u r e m a y b e i n c r e a se d t o 1 2 0 ~ i n t h e c as e o f p r e s s u r i s e d e q u i p -

m e n t w i t h a c o r r e s p o n d i n g r e d u c t i o n i n p r o c e s s t im e . T h e r a te o f b l e a c h i n g i n-

c r e a se s w i th the inc r e a se in t e m pe r a tu r e , bu t a t t he sa m e t im e so lu t ion be c om e s

u n s t a b l e a n d d e g r a d a t i o n o f c o t to n i n c re a s e s . B e l o w 8 0~ t h e e v o l u t i o n o f

pe r h ydr o xy l ion i s ve r y s low so a lso the ra t e o f b l e a c h ing .

6 . 3 .3 . 3 E f f e c t o f c o n c e n t r a t i o n o f li q u o r

T h e o p t i m u m c o n c e n t r a t io n o f h y d r o g e n p e r o x i d e d e p e n d s o n n u m b e r o f f ac -

to r s na m e ly l iquor r a tio , t e m p e r a tu r e a nd c l a s s o f fib re . I n the ba tc h p r oc e ss u s ing

k ie r s a bou t 2 - 4% ( o .w . f . ) hy dr og e n pe r ox ide i s su f f ic i e n t f o r c o t ton f a b r i c s w i th a

l iquor r a t io o f 10 :1 to 20 :1 . I n the c on t inuo us p r oc e ss , t he c o t ton f a b r i c s a re s a tu -

r a t e d wi th b l e a c h ba th c on ta in ing 1 - 2% ( o .w . f .) hydr oge n pe r ox ide . Ve r y h igh c on-c e n t r a t ion m a y da m a ge the f ib r e .

6 . 3 .3 . 4 E f f e c t o f t i m e

T h e t i m e r e q u i r e d t o b l e a c h w i t h h y d r o g e n p e r o x i d e d e p e n d s o n t e m p e r a t u r e ,

c l a s s o f fib r e a nd e qu ip m e n t u se d f o r b l e a c h ing . I n ge ne r a l , the t im e o f b l e a c h in g i s

i n v e r s e ly p r o p o r t i o n a l t o t h e t e m p e r a t u r e o f th e b l e a c h i n g b a t h . C o t t o n m a y b e

b le a c h e d in ope n k ie r s by c i r c u la t ing he a te d hydr o ge n pe r ox id e so lu t ion (8 8 -9 5~

for 6 to 10 hou rs .

6 .4 B l e a c h i n g o f W o o l w i t h H y d r o g e n P e r o x i d e

The na tu r a l c o lou r o f a n im a l f ib r e i s c lo se ly r e l a t e d to the c ha r a c te r o f e nv i r on -

m e n t in wh ic h the a n im a l l ive s [ 19 ] . W ool lo ts c om ple te ly f r e e o f da r k f ib r e s do no t

e x i s t [ 2 0] . I n a n im a l ( a n d h u m a n ) h a i r t w o k i n d s o f p i g m e n t s o c c u r , n a m e l y

e u m e l a n i n ( r e s p o n s i b l e f o r b l a c k , d a r k b r o w n a n d g r e y c o l o u r s a n d c o m m o n l y

r e f e r r e d to a s m e la n in ) a nd phe or ne la n in ( p r e se n t in ye llow, r e dd i sh - b r ow n a nd r e d

h a ir ). B o t h a r e t h o u g h t t o b e f o r m e d b y d i f f e re n t m e c h a n i s m s a n d c h e m i c a l ly d i f-

f e r e d [21 ] . Eu m e la n in i s f o r m e d b y e nz ym a t i c ( ty r os ina se ) ox ida t ion o f ty r os inea n d p o l y m e r i s a t i o n o f s ev e r a l o x i d a t i o n p r o d u c t [ 22 ]. P h e o m e l a n i n o c c u r s i n f o rm

of d i sc re t e g r a nnu le s . M e la n in g r a nnu le s c a n oc c u r in the c o r t e x o r in the c u ti c le .



17 4 B le a c h ing o f Te x t i l e s

S c o ur e d W ool va r i e s in sha de f r om the l i gh t c r e a m o f wo o l s c on s ide r e d to ha ve

g o o d c o l o u r t o d i s c o l o u re d , u r i n e - s ta i n e d w o o l s a n d t h e n e a r b la c k o f h e a v i ly p i g -m e n t e d w o o l . B l e a c h i n g i s c o m m o n w i t h al l t h e se w o o l s w h i c h h a s b e e n w e l l r e -

v i e w e d [ 2 3 -2 5 ] . T h e m a i n p r o b l e m i s t h a t th e w h i t e n e s s o f w o o l a t t a in e d d u r i n g

b l e a c h i n g i s n o t p e r m a n e n t . W o o l t e n d s t o y e l l o w o v e r a p e r i o d o f a t m o s p h e r i c

e x p o s u r e o f a p p r o x i m a t e l y s ix m o n t h s . B l u e i n g o r o p ti c al w h i t e n e r s m a y b e a d d e d

e i the r to b l e a c h l iquor o r to f ina l r in se ba th . T he m a in b l e a c h ing a ge n t s f o r woo l a r e

o x i d i s i n g a n d r e d u c i n g a g e n ts . A m o n g s t t h e o x i d i s i n g a g e n ts h y d r o g e n p e r o x i d e i s

m o s t c o m m o n l y u s e d b e c a u s e s o d i u m h y p o c h l o r i t e g i v e s a d e e p r u s t c o l o u r a n d

sod iu m c h lo r i te de ve lops p ink c o lou r a t ion on woo l . T r a d i t iona l ly woo l i s b l e a c he d

by ox ida t ive p r oc e sse s e i the r in the p r e se nc e o f a lka l ine s t a b i li s e r o r und e r a c id i c

c ond i t ion o f hy dr og e n pe r ox ide [27, 28 ] .

6 .4 . 1 B l e a c h i n g o f w o o l in a l k a l in e h y d r o g e n p e r o x i d e s o l u t io n

In the a lk a l ine con di t ion , w ool i s t r ea ted a t pH 8-10 w i th a 1 .5-3 vol. so lu t ion of

hydr oge n pe r ox ide c on ta in ing 2 - 3 g /1 s t a b i l i s e r , wh ic h m a y be sod ium s i l i c a t e o r

s o d i u m p y r o p h o s p h a t e. A m i x tu r e o f s o d iu m p y r o p h o s p h a t e a n d a m m o n i u m o x -

a la te i s a l so use f u l f o r u se a s a s ta b i l i se r i n b l e a c h ing o f woo l w i th hydr o ge n p e r ox-ide [28 ] . B le a c h ing m a y be c a r r i e d ou t a t 50 ~ f o r 3 to 5 h a nd the n r in se d , t r e a te d

wi th d i lu t e a c e ti c a c id a nd r in se d a ga in . The l e ve l o f wh i t e ne ss c a n be c on t r o l l e d by

c o n c e n t r a t i o n o f h y d r o g e n p e r o x i d e , l e n g t h o f t re a t m e n t t i m e , p H a n d t e m p e r a t u r e

o f t r e a t m e n t b a t h .

6 . 4 .2 B l e a c h i n g o f w o o l in a c i d i c h y d r o g e n p e r o x i d e s o l u t io n

I n the a c id p r oc e ss w oo l i s tr e a t e d wi th a so lu tion o f hyd r oge n p e r ox ide c on-

t a in ing f o r m ic a c id (2 .5 g / l) a t pH a r ound 4 to 4 .5 a t r oom te m pe r a tu r e . T he t r e a t e d

wo o l i s t he n squ e e z e d to r e m ove e xc e ss l i quor a nd pa s se d in to a d r ie r whe r e b l e a c h -

ing t a ke s p l a c e . Age in g i s p r e f e r a b le be c a use the c o lou r o f the woo l c on t inue s to

im pr ov e f o r 24 - 48 h a f t e r d r y ing . C i t ri c a c id a c t iva t e s pe r ox ide b l e a c h in g o f wo o l

b e t w e e n 8 0 a n d 60 ~ [ 29 ]. A c t i v a t ed h y d r o g e n p e r o x i d e b l e a c h i n g o f w o o l w i t h

r e d u c e d b l e a c h i n g t im e a n d d a m a g e i s r e p o r t e d b y t r e at m e n t i n a b a t h c o n s i s t i n g a

m ix tu r e o f o r ga n ic s a l t s t ha t f o r m c a r boxy l i c a c ids [30 , 31 ] . Fu r the r , b l e a c h ing

wi th a lka l ine a nd a cid i c hyd r oge n pe r ox ide a t 6 0~ c a n be im pr ove d by a dd ing 100

to 20 0 g /1 o f u r e a [32 ] . The p r e c a u t ions du r ing b le a c h ing a r e e xa c t ly the sa m e a st h o s e n e e d e d i n th e b l e a c h in g o f c o tt o n w i t h h y d r o g e n p e r o x i d e. T h e a d v a n t a g e s o f



Bleach ing of Tex t i les 175

ac id p rocess a re lowe r chem ica l degrada t ion o f wool , r ins ing a f te r b leach ing i s no t

r eq u i r ed an d n o t en d en cy f o r b l eed in g o f co lo u red th read in g s .6 . 4. 3 A l k a l i n e p e r o x i d e b l e a c h i n g f o l l o w e d b y h y d r o s u l p h i t e t r e a t m e n t o f w o o l

W here an exc e l len t s tab le b leach i s requ i red , espec ia l ly i f it is to be fo l lowed by

the app l ica t ion o f a f luorescen t b r igh teners , then an a lka l ine perox id e b leach fo l-

low ed by s tab i l i sed hydrosu lph i te t rea tmen t is necessary . B leach ing i s car r ied ou t

fo r 3 -5 h a t 50~ wi th a lka l ine hyd rogen perox ide fo l low ed by a second trea tm ent

w i th 2 g/1 o fh yd ros u lp h i te so lu t ion to ra ise the whi teness fu r ther .

6 .4 . 4 M o r d a n t i n g a n d p e r o x id e b l e a c h i n g o f w o o l

Th e b es t ch an ce f o r an e f f ic i en t b l each in g o f h ig h ly p ig m en ted w o o l w i th m in i -

m u m f ib r e d am ag e i s p r o v id ed b y th e u se o f m e ta l c a t a ly s ts i n a m o r d an t in g s tep

p r eceed in g p e r o x id e b l each in g .

M o r d an t in g i s d o n e in p r e sen ce o f h y p o p h o sp h o r o u s ac id an d it is an ex ce ll en t

s tab i l i se r fo r iron ( I I) ions unde r mo rdan t ing condi t ions (Tab le 6 .2) . M ore im por-

T A B L E 6 .2

Mo r d an t in g an d Rin s in g C o n d i t io n s f o r P ig m en ted W o o l [33 ]_

Mordan t ing Rins ing

Iron (II) sulpha te hep tahy drate 10 g/1

Hy pop hosp horo us ac id (50%) 3-4 g/1

( reduc ing agen t)

Form ic ac id To pH 3 to 3 .5

Tem pera tu re (~ 80

Tim e (rain) 60

8O

20

tan t ly , cys t ine suf fe rs hard ly any a t tack f rom hyp oph osph orous ac id unde r condi -

t ions tha t favour d isu lph ide sc iss ion induced by su lphur con ta in ing reduc ing agen ts

[34-36] . It is poss ib le to avo id the use o f fo rma ldehyd e in p igm ent b leach ing w hen

a m i ld r ed u c in g ag en t su ch a s h y p o p h o sp h o r o u s ac id i s p r e sen t. H o wev e r , w i th

h y d r o su lp h i t e , f e rr o u s su lp h a te an d am m o n iu m su lp h ate m o r d an t in g , ad d i t io n o f

4% of 40% formaldehyde as a c ross- l ink ing agen t to p reven t f ib re degrada t ion i s

suggested [37 , 38] . Rins ing fo l lowing the mordan t ing s tep p roved to be c r i t ica l

wi th regard to se lec t iv i ty and consequen t ly to f ib re damage . A normal co ld r insew ould rem ove v i r tua l ly no i ron f rom the f ib re .



176 B le a c h ing o f Te x t i le s

I n the se c o nd s t age , b l e a c h ing i s c a r r ie d ou t i n a lka l ine c on d i t ion o f hyd r oge n

pero xide . I ron tha t se t t le s on the sur face and ins ide the f ibre ac ts a s a ca ta lyse r andbr ings a bou t e nha nc e d b le a c h ing a c t ion by e x t r e m e ly r e a c t ive r a d ic a l s ( HO. a nd

HO 2 . ) t ha t a r e p r oduc e d f r om ox id i s in g a ge n t . The b le a c h in g c ond i t ions a r e

sum m e r i se d in Ta b le 6 .3 . Te t r a sod ium pyr ophospha te ( d iphospha te ) ( 10 g / l ) i s a

T A B L E 6 . 3

B l e a c h i n g C o n d i t i o n s f o r W o o l P i g m e n t e d i n th e B u l k

F ib r e type U202( 35%) pH Te m p. T im e

(m l/1 ) (adjus ted wi th (~ ( ra in)a m m . h y d r o x i d e )

K a r a k u l W o o l , C a s h m e r e ,

A lpa c a , C a m e l , Ya k .

Rabbi t , Chicken fea the r .

Goa t , Hum a n ha i r.

25-45 8 -8.5 50-60 45-1 80

20-40 8 -8.5 50-60 45-1 20

30-50 8 .5 60-70 60-180

goo d s t a b i l i s ing a g e n t in pe rox ide b a th ha v ing l iquor r a t io o f 15 :1 . Af te r b l e a c h ing

the woo l i s t ho r ou gh ly r in se d w i th wa te r. The r e t e n t ion o f non- se l e c t ive f e rr ousi o n s o n w o o l f o l lo w i n g r i n s in g a n d s u b s e q u e n t b l ea c h i n g w i th h y d r o g e n p e r o x i d e

le a ds to a n unde s i r a b le l i gh t b r ow n d i sc o lou r a t ion f r om f e r ri c spe c ie s . S e le c t ive ly

b le a c he d f ib r e m a y be g ive n a s e c ond s te p r educ t ive o r ox ida t ive b l e a c h ing to y i e ld

wh i t e r m a te r i a l f o r c us tom e r r e qu i re m e n t .

6 . 4. 5 S e q u e n t i a l o x i d a t i v e a n d r e d u c t i v e b l e a c h i n g o f w o o l

The r e a r e two a ppr oa c he s f o r s e que n t i a l ox ida t ive / re duc t ive b l e a c h in g o f woo l

in a s ing le ba th . I n the f i rs t a pp r oa c h , f o l lowing the ox ida t ive b l e a c h ing o f woo l

us ing hy dr og e n pe r ox ide , t he pe r ox ide ba th i s c onve r t e d to r e duc t ive ba th by a dd i -

t ion o f th iou r e a a nd b le a c h ing c on t inue s w i thou t the ne e d f o r a f l e sh ba th f o r the

r e duc t ive s t eps . I n the se c ond a pp r oa c h a f te r b l e a c h ing o f woo l w i th ox ida t ive

hy dr og e n pe r o x ide ( a lka line o r a c id ic ) , t he r e m a in ing a c t ive hydr oge n pe r o x ide i s

de c om pose d by the use o f a n o r ga n ic c a t a lys t , a nd f ina l ly a r e duc t ive b l e a c h ing

a ge n t i s a dde d to the ba th w i th ne c e s sa r y pH a d jus tm e n t .

R e ga r d ing the f i r s t a pp r oa c h va s t a m oun t o f i n f o r m a t ion i s a va i l a b le on th io -

u r e a [39 - 43 ] a nd the r e a c t ion m e c h a n i sm c a n be re p r e se n te d a s :

pH4.5-5.5 N - C ( - N H ) - SO2H + 2 H 2 02 N - C ( - N H ) - S H + 2 H 2~ 2 ) H 2

t h i o u r e a t h i o u r e a d i o x i d e



Bleach ing of Tex t iles 177

H 2 N - C ( = N H ) - SO 2H + 2 O H - p H 7 - 8 ), H2 N - C ( - N H ) - O H + S O 2

urea su lph ina te ionSO2 - + [ ch r o m o p h o r e ] + SO 4 2--}- [ r ed u ced ch r o m o p h o r e ]

The re ac t ion rou te and the f ina l p roducts o f the reac t ion o f th iourea w i th hydro-

g en p e r o x id e a re v e r y m u ch d ep en d en t o n th e m o la r ra t io o f r eac t an t s an d th e p H o f

the reac t ion . T h iourea d iox ide i s p rodu ced in s itu and reduc t ive b leac h ing o ccurs .

Th e b l each in g co n d i t io n s d ev e lo p ed a re , a lk a lin e h y d r o g en p e r o x id e b l each in g a t

60~ fo r 60 m in fo l lowed by an add i t ion o f th iourea , pH ad jus tme nt , and subse-

quen t reduc t ive b leach in g a t 60~ fo r 25 m in fo l low ed by wash ing and r ins ing .

Th e r e a r e n u m b er o f p a t en t s o n th e se n ew b leach in g p r o cess [4 4, 4 5 ] .

In the sec ond app roach , the add i t ion o f th iourea d i rec t ly to hydrog en perox ide

ba th i s avo ided because i t wa stes considerab le reduc t ive agen t due to la rge excess

of hydrogen perox ide usua l ly le f t in the b leach ba th . To avo id th is p rob lem, o r -

gan ic ca ta lys ts tha t decompose hydrogen perox ide a re added and f ina l ly th iourea

d iox ide o r me thane su lph ina te i s added d i rec t ly to the ba th w i th nec essary pH ad-

jus tm ent . The re a re m any inorgan ic ca ta lys ts tha t read i ly decomp ose hyd rogen per -

ox ide , bu t s o m e (F e B+, Fe 2+, Cu 2+, M n 2+) tend to cause excess ive da m age as wel l asd isco lou ra t ion o f wool . C o 2§ i s the on ly m eta l ca t ion repo r ted to cause no dam age

or d isco loura t ion [46] .

Desp i te the advan tages o f us ing th iourea to induce in s i tu reduc t ive b leach ing ,

some po ten t ia l users o f s ing le ba th p rocesses hes i ta te to use i t due to the tox ic

n a tu r e o f th io u r ea . F u r th e r m o r e , t h io u r ea th o u g h ea s i ly h an d led an d th o r o u g h ly

consu m ed, i s c lass i f ied as carc inogen u n l ike i ts ox id ised counterpar t , th iourea d i -

ox ide ( fo rmamid inesu lph in ic ac id) .

Tri thio cya nuric acid (TT CA ; s- tr iazine-2, 4 , 6- tr i th iol) is a cyclic analog o f thi o-

S -

- S ~ L N H 3N a + ~ ~ S -

H ~ N S ~ - ' ~ / ~ "

Thiourea Sod ium sa l t t r i th iocyanur ic ac id (Na3TTCA)

urea . Na3TTC A is no t c lass i f ied as a carc inogen and th iourea m ay be rep laced by i t.

Na3TTCA is most e f fec t ive a t 90% of the s to ich iometr ic weigh t to perox ide , as




o p p o s ed t o 70% f o r t h io u rea . T h e N a3 T T CA i s m o r e s en s i ti v e t o t h e p H o f t h e ri n s e

b a th t h an t h e t h io u r ea p r o ces s an d i s m o r e ex p en s iv e t h an t h io u r ea . N ev e r th e l e s s ,t h e a t t r ac t i v en es s o f u s in g N a3 T T C A i s t h e av o id an ce o f a p o t en t ia l c a r c in o g en an d

a c h i e v e m e n t o f e x c e p t io n a l w h i t e n e s s o v e r c o n v e n ti o n a l p e r o x id e b l e a c h i n g

[ 4 7 , 4 8 ] .

6 . 4. 6 B l e a c h i n g o f w o o l w i th e m u l s i o n o f h y d r o g e n p e r o x i d e

W o o l h as b ee n s u cces s f u l l y b l each ed w i th a s tab l e em u l s io n o f h y d r o g en p e r o x -

id e [4 9 ] o r p e r m o n o s u lp h u r i c ac id [ 5 0] i n p e r ch lo r o e th y l en e . By th i s m ean s i t ap -

p ea r s t o b e p o s s ib l e t o o b ta in t h e s am e d eg r ee o f w h i t en es s a s t h a t a t t a in ab l e i n a

s t an d a r d aq u e o u s b l each , b u t m o r e r ap id ly an d w i th th e u s e o f l e s s p e r o x id e . N o

s t ab i l i s in g o r ac t i v a t in g ag en t s a r e n eed ed , b u t th e b l each in g o f w o o l i n p e r ch lo r o -

e t h y l e n e s e e m s t o b e m o r e d e l e te r io u s t o m e c h a n i c a l p r o p e r ti e s o f b l e a c h e d w o o l

th an eq u iv a l en t aq u eo u s p r o ced u r e .

6 .5 B l e a c h i n g o f S il k w i t h H y d r o g e n P e r o x id e

T h e n a tu r a l co lo u r o f s i l k t h r ead d i f f e r s d ep en d in g u p o n th e t y p e o f s i l k w o r m

an d i t s f eed in g h ab i t . A l th o u g h th e b u lk o f th e n a tu r a l d y e s tu f f su ch a s ch lo r o p h i l ,

x an th o p h i l an d ca r o t i n a re to b e f o u n d in t h e s i lk g u m , th e d eg u m m ed m u lb e r y s i lka l s o h as s t r o n g y e l l o w i s h i n h e r en t co lo u r . S in ce s o m e o f t h e s e r ic in i s t en ac io u s ly

h e l d b y f ib r io n , c o m p l e t e e l i m i n a t i o n o f c o l o u r b y d e g u m m i n g i s n o t a c h i e v e d .

T h u s , t h e f ab r i c s m an u f ac tu r ed f r o m y e l l o w r aw s i l k r e t a in a y e l l o w i s h t i n t a f t e r

b o i l i n g - o f f . T h i s n a tu r a l y e l l o w i s h t i n t o n s i l k i s d es i r ed b y s o m e f a s h io n d es ig n e r s

a s a ' s o f t w h i t e ' o r n a tu r a l s h ad e . T h e d es i r ed d eg r ee o f w h i t en es s can b e r e l a t iv e ly

e a s i ly a c h i e v e d w i t h B o m b y x m o r i s il k on b l ea c h i n g . W i t h tu s s a h s i l k t h e y e ll o w -

i s h co lo u r in g o f th e f i b r io n i s co n s id e r ab ly m o r e i n t en s iv e . O n e r ea s o n f o r t h is i s

tha t wi th the tu ssah s i lk the ser ic in a l so pen et ra tes the ac tua l s i lk f ib re , so tha t the

n a tu r a l d y es tu f f s l en d t h e t u s s ah f i b r io n a t y p i ca l b r o w n i s h y e l l o w to g r een i s h y e l -

l o w co lo u r . T h e n a tu r a l co lo u r in g m a t t e r i s t h e t an n in o f th e o ak t r ee l eav es o n

w h ich t u s s ah s i l k w o r m i s f ed . T h e b l each in g p r o ces s f o r t u s s ah s i l k t o g e t w h i t e

f ab r i c i s t h u s u s u a l l y v e r y d i f f i cu l t , w h ich m ak es s u ch s i l k s u n s u i t ab l e f o r w h i t e

f ab r i c s o r f o r ce r t a in p as te l t o n es . T h e s i lk m ay b e b l eac h ed b y o x id a t i v e a s w e l l a s

r ed u c t io n m e th o d s . I f a v e r y h ig h d eg r ee o f w h i t en es s i s r eq u i r ed , a co m b in a t i o n o f

b o th m e th o d s i n t h e f o rm o f d o u b le b l eac h i s ap p l ied .T h e b e s t m e t h o d o f b l e a c h i n g s i lk i s t h e u s e o f h y d r o g e n p e r o x i d e i n a s e p e ra t e



B l e a c h i n g o f T e x t il e s 179

b a th . T h e p e r h y d r o x y l i o n o r ev en a to m ic o x y g en i s r e s p o n s ib l e f o r t h e o x id a t i o n

e f f ec t o n t h e o r g an i c co lo u r in g m a t t e r p r e s en t i n s i lk an d t h u s f o r b l eac h in g e f fec t .T h e r ec ip e s f o r b l eac h in g tw o v a r i e t i e s o f si l k w i th h y d r o g en p e r o x id e a r e g iv en in

T ab le 6 . 4 . T h e m a te r i a l a f t e r d eg u m m in g i s en t e r ed i n to t h e p r ep a r ed b l each in g

T A B L E 6 .4

R e c i p e f o r B l e a c h i n g S i l k w i t h H y d r o g e n P e r o x i d e

C h e m i c a ls M u l b e r y W i l d s il k

s i lk ( tussah , m ug a, e r i )

Hy d r o g en p e r o x id e (3 5 % b y w t . ) 1 5 -2 0 m l /1 2 0 - 3 0 m l /1Sta bilis er 2 g/1 4 g/1

M : L r a t i o 1 : 2 0 1 : 3 0

T em p er a tu r e (~ 75 - 80 80 - 90

Tim e (h) 1 -2 3 -4

bath a t 40~ W ith these f ib res , w hich are sens i t ive to a lka l i , the a lka l i nec essa ry fo r

a c t i v a ti o n o f h y d r o g e n p e r o x i d e m u s t b e a d d e d t o t h e b le a c h i n g b a t h s h o u l d b e

a m m o n i a o r t e t ra s o d i u m p y r o p h o s p h a t e . T h e p H v a l u e o f t h e b l e a c h i n g l iq u o r s

s h o u ld l i e b e tw een p H 8 . 5 - 9 . S t ab i l i s e r s a r e ad d ed t o t h e b a th t o ach i ev e a s l o w

s ep e r a t i o n o f t h e o x y g en n ee d ed f o r t h e b l each in g e f f ec t . W a te r g l a s s , w h ich i s

o f t en u s ed a s a s t ab i li s e r , s h o u ld n o t b e u s ed f o r b l each in g s i lk , b ec au s e o w in g t o

the p rec ip i ta t io n o f s i l i c ic ac id the s i lk can ge t a hard , b r i t t l e ha nd le [51 ] . In th i s

cas e , t e t r a s o d iu m p y r o p h o s p h a t e an d f a t ty p r o t e in co n d en s a t e s a r e t h e i d ea l ch o i ce .

T h e m i x t u r e s o f s o d i u m s i li c a te a n d t r is o d i u m p h o s p h a t e o r o r g a n o p h o s p h a t e s e x -

e r t a g r ea t s t ab i l is i n g e f f ec t o n p e r o x id e an d h e lp t o co n t r o l b l eac h in g ac t io n . G en -e r a ll y , o n e s h o u ld co n s id e r w h e th e r in s t ead o f t h e s eem in g ly co n t r ad i c to r y m e th o d

o f u s in g a c t i v a to r s o n t h e o n e h an d an d s t ab i l i se r s o n th e o th e r h an d , i t w o u ld b e

b e t t e r to h a v e e x a c t m e t e r i n g o f t h e h y d r o g e n p e r o x i d e s o lu t io n . T h e d i s p e n s in g

s y s t e m s t h a t m o s t d y e h o u s e s a r e n o w u s i n g m a k e t h i s f e a s i b l e . H a r d w a t e r w i t h

m e ta l l i c s a l t s o r im p u r i t ie s i s av o id ed a s t h e m e ta l s ac t a s ca t a ly s t an d w e ak e n t h e

s il k . It is ad v i s ab l e t o u s e s t a in le s s s t ee l o r a lu m in iu m v es s e l an d r o d s . B l each in g

ab o v e t h e s p ec i f i ed t em p er a tu r e s l o w er t h e t en s i l e s t r en g th o f s i l k an d b eco m es

y e l lo w . T h e b a th i s g r ad u a l ly r a i s ed t o r eq u i r ed t em p er a tu r e i n 1 h an d b l each in g i s

d o n e a t t h i s t em p er a tu r e f o r s p ec i f i ed t im e . W h er ea s b l each in g o f m u lb e r y s i lk is




c om ple te a f t e r a bou t 2 hour s , t he t im e r e qu i r e d f o r b l e a c h ing tu s sa h s i lk c a n be a

lo t long e r de pe nd in g on the o r ig in a nd inhe r e n t c o lou r . The s i lk a f t e r b l e a c h in g i st h o r o u g h l y r i n s e d f i r st w i th w a r m w a t e r a n d t h e n w i t h c o l d w a t er , h y d r o e x t r a c t e d

a n d d r ie d . S t a n d i n g b a t h s o f p e r o x id e c a n b e u s e d b y r e p l e n i s h i n g t h e b a t h w i t h

1 /3 rd the qu a n t i ty o f hyd r oge n p e r ox ide a nd 1 /4th the qua n t i ty o f st a b i l is e r o r ig i-

na l ly t a ke n f o r b l e a c h ing .

S i lk goods to be so ld a s wh i t e r e qu i r e a t r e a tm e n t w i th 0 .0 8 to 0 .5% op t i c a l

w h i t e n in g a ge n t a long w i th 0.5% g la ube r ' s s a lt at 45~ f o r 20 m in a t pH 4 to 5 w i th

the a dd i t ion o f a ce t i c ac id . U l t r a m a r ine B lue i s a l so r e c o m m e nd e d in the op t i c al

b r igh te n in g ba th to ob ta in a b lu i sh t i nge to the wh i t e s i lk goods .

6 .6 B l e a c h i n g o f S y n t h e ti c F ib r e s w i t h H y d r o g e n P e r o x id e

6 .6 .1 B l e a c h i n g o f r e g e n e r a t e d c e l lu l o s e

Fi la m e n t v i sc ose r a yon m a y no t r e qu i r e b l e a c h ing s inc e th i s is no r m a l ly c a r r i e d

ou t du r ing m a nuf a c tu r e . Howe ve r , v i sc ose in s t a p le f o r m r e qu i r e s b l e a c h ing a s i t

m a y no t ne c e s sa r i ly inc lude a b l e a c h ing t r e a tm e n t du r ing it s m a nu f a c tu re . T he sa m e

r e a ge n t s a s those use d f o r b l e a c h ing l ine n a nd c o t ton f a b r i c s a r e u se f u l f o r t he se

f ib r es . F o r v e r y g o o d w h i te n e s s , r a y o n m a y b e b l e a c h e d o n a j i g g e r w i t h a l k a li n eh y p o c h l o r i t e o r c o m b i n e d s c o u r a n d b le a c h u s i n g h y d r o g e n p e r o x i d e ( up t o 1 v o l.

s t r e ng th ) c on ta in ing sod ium s i l i c a t e a nd a lka l ine de te r ge n t s - a t a t e m pe r a tu r e o f

a bou t 7 0~ The p r e se nc e o f he a v y m e ta l s ( f rom Xa n tha te hydr o ly s i s s t a ge ) m a ke s

the use o f pe r ox ide a ha z a r d ous p r oc e ss . I t is a l so poss ib l e to u se pe r a c e t i c a c id

w i t h v i s c o s e r a y o n .

6 . 6 .2 B l e a c h i n g o f a c e ta t e f i b r e s

T h e w h i t e n e s s o f th e f a b ri c m a d e o f a c et a te m a y b e i m p r o v e d b y t r e a t m e n t w i t h

hy dr o ge n pe r ox ide ( 30 %) , 1 -3 g /1 in p r e se nc e o f sod ium s i li c a te , 0 .3 g /1 . Du r ing

th i s t r e a tm e n t the a lka l in i ty o f t he ba th a nd the r e qu i r e d t e m pe r a tu r e shou ld be

c a r e f u l ly m a in ta ine d . T he pH o f the b l e a c h ba th shou ld no t be g r e a te r t ha n 9 a nd

t r e a tm e n t f o r 1 h at 45~ g ive s c om b ine d sc our a nd b le a c h ing w i th the a dd i t ion o f

non - ion ic de te r ge n t .

6 . 6. 3 B l e a c h i n g o f a c r y li c f ib r e s

C e r ta in a c r y l i c f ib re s shou ld no t be c h lo r i t e b l e a c h e d be c a us e o f the ir t e nde nc y

to ye l low /or loose s tab il i ty to l ight. M any f luorescent br ighteners added to the chlor i teba th a r e a l so no t s t a b le a nd suc h m a te r i a l s m a y e xh ib i t a n a c c e le r a t e d f a de whe n




e xpose d to sun l igh t i n we t a lka l ine c ond i t ion . S uc h f ib r e s c a n be b l e a c he d wi th

hyd r oge n pe r o x ide o r hydr osu lph i t e s . How e ve r , t he ne e d f o r b l e a c h ing va r i e s w i thdifferent acrylic f ibres. Acri lan 16 is suff ic iently white for m os t purp oses, b ut Acri lan

16 56 ha s a m or e ye l lowish b r own na tu r a l c o lou r . Or lon 42 ha s a c o lou r wh ic h i s

in t e r m e d ia t e be twe e n na tu r a l a nd b le a c he d c o t ton .

6 .7 A d v a n t a g e s a n d D i s a d v a n t a g e s o f P e r o xi d e o v e r H y p o c h l o r i t e B l e a c h in g

Advantages :

(i ) Pe r ox ide i s a n un ive r sa l b l e a c h ing a ge n t a nd c a n be e m ploy e d f o r woo l ,

s i lk as we l l a s co t ton . I t i s spec ia l ly su i ted to the b leachin g of union fabr ics

c on ta in ing b o th c o t ton a nd woo l o r s ilk .

( ii ) Hy dr og e n pe r ox ide i s a m i lde r r e a ge n t tha n hypo c h lo r i t e a nd the de g r a d -

ing e f f e c t o f pe r ox ide b l e a c h ing on c e l lu lose i s le s s in f lue nc e d tha n i s the

c a se w i th hyp oc h lo r i t e .

( ii i) Pe r ox ide i s c a pa b le o f c on t inu ing the sc our ing a c t ion s im ul t a ne o us ly w i th

the b l e a c h ing a c t ion , t hus a s ing le s t a ge c om bine d sc our a nd b le a c h o r a

c o n t i n u o u s m e t h o d i s p o s s i b le u s i n g h y d r o g e n p e r o x i d e .

( iv) Pero xide b le ach ing i s in gene ra l le ss l iab le to have ad verse e f fec t on dye dth r e a ds . The w h i t e e f f e c t is good a nd pe r m a ne n t a nd the r e i s l es s r isk o f

ye l low ing a t a la te r s tage .

( v) Th or ou gh r in s ing f o l lowe d by sc our ing o r a n t i c h lo r t r e a tm e n t is r e qu i r e d

wi th hypoc h lo r i t e b l e a c h ing , whe r e a s w i th pe r ox ide a c om p a r a t ive ly sho r t

r ins ing suf f ices .

( v i) W i th hyd r oge n pe r ox ide , t he re is no da nge r o f e qu ip m e n t c o r r os ion , no

unp le a se n t o dour s a nd no l im i t a t ions a s to p r oc e ss ing t e c hn ique s .

( v ii ) I nc r e a s ing s t ri c t c on t r o l ove r the d i sc ha r ge o f AO X f r om c h lo r ine b l e a c h -

ing l iquor s ha s l e d to a g r e a te r a dva n ta ge o f pe r ox ide p r oc e sse s f o r b l e a c h -

ing ce l lu los ic f ibres [52-54] .

D i s a d v a n t a g e s 9

(i) B le a c h ing wi th pe r ox ide i s c os t l i er t ha n tha t o f h yp oc h lo r i t e o r b l e a c h ing

powde r .

( ii ) Hy dr o ge n pe r ox ide b l e a c h ing r e qu i r e s s t ab i l i s at ion usua l ly w i th s i li c a te s

whic h b r ings the r i sk o f f o r m ing r e s i s t s t a in s in subse que n t dye ing , a ndc a use s a bu i ld - up o f ha r d c r ys t a l li ne de pos i t s on p l a n t a nd m a c h ine r y

c a us ing a b r a s ion da m a ge to the f a b r ic du r ing pa s sa ge .



182 B l e a c h i n g o f T e x t il e s

(i ii) ' C a t a l y t i c d a m a g e ' o c c u r s d u r i n g h y d r o g e n p e r o x id e b l e a c h i n g o f c o t to n

f a b r ic s a nd r e su l t s i n sm a l l spo t s o f une v e n ly dy e d f a b r ic o r e ve n , i n s e ve r ec a se s , t he f o r m a t ion o f sm a l l ho le s .

( iv) Th ere i s l imi ta t io n in w hi te obta ined on ac ry l ic f ibres . It a l so causes de l -

e t e r ious e f f e c t on sk in w he n u se d in a c onc e n t r a t e d f o r m .

6 .8 B l e a c h i n g w i t h S o d i u m C h l o r it e

C o m m e r c i a l m a n u f a c t u r e o f so d i u m c h l o ri te u n d e r th e tr a d e n a m e o f 't e x t o n e '

b e g a n i n 1 9 3 0s a n d b y 1 93 9 it w a s b e i n g p r o m o t e d f o r c o n t i n u o u s b l e a c h i n g o f

c e l lu los i c t e x t i le s f o r w h ic h pu r pos e US m a nuf a c tu r e r s , M a th ie son A lka l i C o . de-

s igne d a l a r ge c on ve y e r sys t e m . S od ium c h lo r i te ( Na C 10 2) in i ts wh i t e c r ys t a l l ine

f o r m i s h igh ly hy gr osc o p ic in na tu r e . S o l id sod ium c h lo r it e i s s t a b le a t r oom te m -

pe r a tu r e f o r a longe r t im e wh e n i t i s m ixe d w i th sm a l l qua n t i ty o f a lka li ( Na2C O3).

N ow - a - da y s c h lo r i le b l e a c h ing i s inc r e a s ing ly be ing use d f o r po lye s t e r , be c a u se the

c he m is t r y i s be t t e r unde r s tood [55] .

6 .8 .1 M e c h a n i s m o f c h l o r it e b le a c h i n g

S o d i u m c h l o ri te o n d e c o m p o s i t i o n p r o d u c e s a s tr o n g o x i d is i n g g a s k n o w n a s

c h lo r ine d iox ide . Th e low e r the pH va lue s a n d h ighe r the t e m pe r a tu r e ( a bove 7 0 ~of b l e a c h ba th , t he g r e a te r is the spe e d o f de c om pos i t ion [56] . The r a t e o f c h lo r ine

d iox ide f o r m a t ion i s p r opor t iona l t o the c onc e n t r a t ion o f sod ium c h lo r i t e in the

so lu t ion . C h lo r ous a c id ( HC 10 2) tha t i s f o r m e d i s uns t a b le a nd d e c om pose s to c h lo -

r ine d iox ide (C 10 2) w h ic h i s t he a c i tve spe c ie s so f a r a s b l e a c h in g i s c onc e r ne d .

M a x i m u m c h l o r in e d i o x i d e i s fo r m e d b e t w e e n p H 2 . 5 a n d 3 .0 . In th e a b s e n c e o f

m e ta l i ons a nd t e x t i l e s , t he r a t e o f f o r m a t ion o f c h lo r ine d iox ide a ppr ox im a te ly

dou b le s f o r e a c h 0 .4 - pH d r op , in the 3 .0 - 5 .0 ra nge , a t 8 5~ Add i t ion o f a n a c id

suc h a s f o r m ic , a c e t ic o r pho spho r i c a c id is r e c o m m e nd e d so tha t pH l ie s be tw e e n

3 to 5 . I f t he pH d r ops be low 3 .0, c o t ton f ib re i s s e ve r e ly da m a ge d be c a use we a k

a c id ( HC 10 2) a nd s t r ong a c ids ( HC 1 a nd HC 10 3) ar e f o r m e d wh ic h hy dr o lyse the

c e l lu lose . On the o the r ha nd , t he lo s s o f oxy ge n e v o lu t ion f r om ho t c h lo r it e so lu -

t ion wh e n c o t ton i s a dde d a l so sugge s t s t ha t c h lo r it e i on r a the r tha n c h lo r ous a c id i s

r e spon s ib le f o r b l e a c h ing [57] .

2Na C 10 2 + H2S O4 --> Na2SO 4 + 2HC102

HC102 --> C 102 + H §H C 1 0 2 - -) , H C1 + 2 0




Aque ous sod ium c h lo r i t e so lu t ions , wh ic h a r e s t a b le unde r a lka l ine c ond i t ions

a r e to be a c t iva t e d by a c id i f i c a t ion . Ac t iva t ion wi th s t r ong a c id p r oduc e s a tox icc o r r os ive c h lo r ine d iox ide ga s . It is t hus ne c e s sa r y to c on t r o l i t s ra t e o f e vo lu t ion .

T e c h n i c a l d e v e l o p m e n t s h a v e b e e n l i n k e d m a i n l y t o c o n t ro l t h e c h l o ri n e d i o x i d e

e vo lu t ion [58 - 6 0] . In p r a c t i c e th i s i s ge ne r a l ly a c h ie ve d by c on t r o l l ing the te m -

p e r a t u r e a n d p H b y a d d i t io n o f b u f f e r s i n th e b l e a c h b a th . T h i s c a n b e a v o i d e d b y

a dd i t ion o f we a k a c id ( wh ic h f o r m s a bu f f e r w i th the a lka l i i n the c h lo r i t e ) o r a

m ix tu r e o f we a k a c id a n d i ts s a l t w t ih a s t r ong ba se [61 ] . S om e a ux i l i a r y p r odu c t s

f u n c t i o n b y g i v i n g a s l o w d e v e l o p m e n t o f a c i d i t y o n h e a t i n g o r l o n g s t r o a g e a t

a m b i e n t t e m p e r a t u r e s . S p e c i a l b r a n d s o f s o d i u m c h l o r i te a r e a v a i l a b le w h i c h c o n -

t a in a c id ge ne r a t ing m a te r i a l s a nd thus a t t a in the re qu i r e d pH, w i thou t f u r the r add i -

t ion on r e a c t ing a t b l e a c h in g t e m pe r a tu r e . A c t iva t ion wi th pe r su lph a te s a bo ve pH 7

[6 2 ], a lde hyd e a t pH 3 - 7 [6 3 ], b r om ide s [6 4 ], s a lt s w i th c o ba l t , n i c ke l a nd m a ng a -

ne se a t pH 5 - 8 .5 [6 5 ], su lphur , s e l e n ium o r fine ly d iv ide d c a r bo n [66 ] a nd c h lo r i -

n a t e d h y d r o c a r b o n [ 67 ] h a v e b e e n p r o p o s e d a n d a ls o a c i tv a t i o n b y o r g a n ic a c id

es te r s such as e thyl lac ta te (1-3 g / l ) wi th addi t ion of sodium ni t ra te (1-3 g / l ) to

inh ib i t c o r r os ion [6 8 ] i s poss ib l e . S od ium hydr oge n o r thophospha te ( Na H2PO4)sod ium f o r m a te w h ic h p r odu c e a c id whe n the l i quor is he a te d a r e a lso sugg e s te d a s

buf f e r s . O r ga n ic e s t e r s suc h a s d i e thy l t a r ta r a t e wh ic h hyd r o lyse s to g ive t a r ta r i c

a c id , o r sod ium c h lo r oa c e ta t e w h ic h l ibe r a te s hydr oc h lo r i c a c id a nd g lyc o l l i c a c ids

dur ing s t e a m ing , ha ve a l so be e n sugge s te d a s bu f f e r s [55 ] . O the r a l t e r na t ive s a r e

the use o f e ithe r spe c ia l a ux i l i a r y p r odu c t s w h ic h l im i t c h lo r ine d iox ide e vo lu t ion ,

f o r e xa m ple , f oa m f o r m a t ion on the b l e a c h l iquor su r f a c e o r o the r c he m ic a l s c a -

p a b l e o f t ra p p i n g c h l o r in e d i o x i d e c h e m i c a ll y .

6 .8 .2 B l e a c h i n g o f c o t t o n w i t h s o d i u m c h l o r it e

C o t ton c a n be e f f e c t ive ly b l e a c h e d wi th so d ium c h lo r i t e (1 - 2% ) a t a pH 4 .0 • 2

c o n t a i n i n g s o d i u m d i h y d r o g e n p h o s p h a t e ( 0 .2 - 0 .5 % ) , s t a b l e fo a m i n g a n d w e t t i n g

a ge n t ( 0 .1 - 0 .25%) , n i t r oge nous c h lo r ine a bso r be r a nd f o r m ic a c id to m a in ta in the

pH. The t e m pe r a tu r e o f the b l e a c h ba th i s r a i s e d to 8 2 - 90 ~ a nd m a in ta ine d a t t h i s

t e m p e r a t u r e f o r 1 - 3 h d e p e n d i n g u p o n t h e m a c h i n e s ( b a t c h w i s e ) e m p l o y e d f o r

b l e a c h i n g . C h e m i c a l s s h o u l d b e a d d e d i n t h e f o l lo w i n g o r d e r : w a t e r , p r e v io u s l y

d i s so lv e d sod iu m n i t ra t e , bu f f e r s a l t s o r o the r c h lo r it e s t a b i l i se r , su r f a c t a n t s , so -d ium c h lo r i te ( p r e - d i s so lve d , i f so lid p r oduc t ) a nd l a s t ly the d i lu t e d a c id . The a dd i -



184 B l e a c h i n g o f T e x t i l es

t ion o f a c id ic m a te r i a ls t o c onc e n t r a t e d sod ium c h lo r it e so lu t ions m us t be a vo ide d .

So dium ni t ra te i s used as a cor ros ion inhib i tor . I t i s not e ssent ia l to use ac id chlor i teso lu t ions in the se m i - c on t inuou s p r oc e sse s ( pa d - r o ll o r pa d - s t a c k ) w he r e e f f e c t ive

l iquor r a tio i s low a nd ne u t r a l c h lo r i te so lu t ions ( 10 g /l ) a r e r e c om m e nd e d . W he n

long ba tc h ing t im e a r e u se d , so da - a sh (1 g / l ) is a dde d to m a in ta in s t a b i l i t y o f the

ba th .

C o t t o n g o o d s t h a t h a v e b e e n p r e p a r e d i n k i e rs a r e a d v a n t a g e o u s l y b l e a c h e d b y

a n a lka l ine sod ium c h lo r it e a c t iva t e d by hy poc h lo r i t e . In th i s m e tho d , c o t ton goods

2Na C 10 2 + N a OC 1 + H 2 0 ~ 2 C I O 2 + N a O H + N a C 1

pa sse s th r ough a s a tu r a to r c on ta in ing ( 1 - 3 g /1 a va i l a b le c h lo r ine ) m ix tu r e o f so -

d i u m c h l o ri te a n d s o d i u m h y p o c h l o r i te a n d a b u f fe r m i x t u r e o f b ic a r b o n a t e o f s o d a

a nd so da - a sh . A n a v a i l a b le c h lo r ine p i c k - up o f 0 .3% ( o .w . f .) i s typ ic a l . I n a c tua l

p r a c t i c e , t he hyp oc h lo r i t e : sod ium c h lo r i te r a t io c a n va r y be tw e e n 3 : 2 a nd 3 : 1,

on a n a v a i l a b le c h lo r ine ba s is . The a c c e p ta b le pH va r i e s f rom 8 .8 to 9 .7 m a in ta ine d

by bu f f e r . Af t e r l e a v ing the sa tu r a to r , t he goods r e m a in s in J - B oxe s o r b ins f o r the

t im e ne c e ssa r y f o r b l e a c h ing , u su a l ly 1 -2 hour s . A t the e nd o f the b l e a c h ing c yc le

the goods a r e wa she d , a n t i c h lo r e d , a nd wa sh e d a ga in .The th i r d m e thod o f a c t iva t ing sod ium c h lo r it e invo lve s the r e a c t ion o f sod ium

c h lo r i te w i th c h lo r ine . The r e a c t ion g oe s to c om ple t ion ve r y ra p id ly . How e ve r , t h i s

2Na C 10 2 + C12 --~ 2C102 + 2NaC1

m e tho d ha s no t ye t found a n a pp l i c a t ion in the indus t r y .

6 .8 .3 B l e a c h i n g o f p o ly e s t e r w i t h s o d i u m c h l o r it e

S yn the t i c po lye s t e r f ib r e s a r e no r m a l ly supp l i e d in a n o f f - wh i t e s t a t e . S om e -

t im e s h igh de g r e e o f w h i t e ne ss i s r e qu i r e d f o r wh i t e goods . The po lye s t e r i s ge ne r -a l ly b l e a c he d wi th sod ium c h lo r i t e in a ba th c on ta in ing sod ium c h lo r i t e ( 50 %) ,

3-5 g / l, form ic ac id to ge t pH 3 .0 for 1-2 h at a tem pera ture of 95~ A sm al l

qua n t i ty o f we t t ing a ge n t c a n be a dde d in the b l e a c h ing ba th . B le a c h ing i s f o l low e d

by a n t i - c h lo r ina t ion wi th th iosu lpha te ( 2 - 3 g /l ) a t 6 0~ f o r 20 m in . F ina l ly , wa r m

(60~ and cold r inses a re g ive n for 10 m inutes .

6 . 8. 4 B l e a c h i n g o f n y lo n w i t h s o d i u m c h l o r it e

N ylo n i s a l so supp l i e d in qu i te wh i t e s t at e . B le a c h ing o f ny lon i s no r m a l ly c a r -

r i e d ou t whe r e the ny lon ha s be e n d i sc o lou r e d by he a t - se t ti ng t re a tm e n t . T he p r ob -

l e m o f d i sc o lou r a t ion i s c om pa r a t ive ly l e s s in the c ase o f ny lon 6 tha n tha t o f ny lon




6 ,6 due to the lowe r t e m p e r a tu r e r e qu i r e d in the sp inn ing p r oc e ss a nd low e r so f t e n -

ing po in t o f ny lon 6 ,6 .N e i t h e r s o d i u m h y p o c h l o r it e n o r h y d r o g e n p e r o x id e is r e c o m m e n d e d f o r b l e ac h -

ing o f ny lon . W he n hyp oc h lo r i t e i s u se d , t he r e is a t e nde n c y f o r c h lo r ine to c om -

b ine w i th se c ond a r y a m ino g r oups , c a us ing de c r e a se in t e ns i l e s tr e ng th . N y lon c a n

be b le a c he d in a ba th c on ta in ing sod ium c h lo r i t e ( 8 0 %) , 1 - 2 g / l , sod ium n i t r a t e ,

1-3 g /l , form ic ac id (85%) , 2 ml /1 for 1 h a t 80-85~ Ace t ic ac id is pre fe r red to

f o r m ic a c id f o r a d jus t ing the pH ( 3 .5 to 4 ) be c a use i t ha s a bu f f e r ing a c t ion on

sod iu m c h lo r i t e so lu t ion in the r e qu i r e d r e g ion . A sm a l l a m oun t o f a c id s t a b le de -

t e r ge n t ( 0 .2 g / l ) m a y be a dde d to the b l e a c h ba th to ha ve a c om bine d e f f e c t o f

sc our ing a nd b le a c h ing a s we l l a s r e duc t ion in the lo s s o f c h lo r ine d iox ide to the

a tm osph e r e due to the f o r m a t ion o f su r f a c e fr o th . An a c t iva to r f o r b l e a c h ing w i th

s o d i u m c h l o ri te i s al so r e c o m m e n d e d s o th a t b le a c h i n g c a n b e c a r r ie d o u t i n n e a r

ne u t r a l pH . A c id don or s o r ga n ic e s t e r s e .g . e thy l la c t a t e a re r e a d i ly hydr o lyse d in

b le a c h ba th a nd sp l i t i n to a l c oho l a nd o r ga n ic a c id . As the hydr o lys i s p r og r e s se s

R - C O O R ' + H 2 0 ~ R C O O H + R ' O H

the o r ga n ic a c id w h ic h i s s lowly l ibe r a t e d r e gu la t e s the the de c o m pos i t ion o f c h lo -r it e . The pH o f the ba th . i s m a in ta in e d w i th in 6 .6 to 6 .0 du r ing the pe r iod o f b l e a c h -

ing . Th e a m oun t o f e thy l la c t a t e a dde d to the ba th de pe nd s on the l i quor ra t io . Fo r

shor t l i quor r a t io 2 - 3 m l /1 a nd f o r long l iquor 1 m l /1 o f e thy l l a c t a t e i s su f f i ci e n t .

S om e t im e s a m m oniu m c h lo r ide i s a l so use d a s a n a c t iva to r f o r b l e a c h ing w i th c h lo -

r it e . B le a c h ing o f d i ff e r e n ti a l dye ing ny lon i s no t no r m a l ly r e c om m e nd e d s inc e th i s

t e nds to l im i t the c on t r a s t e f fe c t s du r ing subse qu e n t dye ing . How e ve r , w he n b le a c h -

ing i s e s se n t i a l a m i ld c h lo r i t e b l e a c h [69 ] c a n be e m ploye d .

6 .8 . 5 B l e a c h i n g o f a c e ta t e f ib r e s w i t h s o d i u m c h l o r i te

I t i s m or e sa f e to c a r r y ou t b l e a c h ing o f a c e ta t e f ib r e s w i th so d ium c h lo r i te tha n

w i t h h y d r o g e n p e r o x i d e . B l e a c h i n g c a n b e c a r r i e d o u t w i t h s o d i u m c h l o r i t e

( 0. 5 -2 g / l) i n p r e s e n c e o f m o n o s u b s t i tu t e d a m m o n i u m p h o s p h a t e ( 0. 5 -2 g / l ) an d

non - ion ic de te r ge n t a t 7 0 -8 0 ~ f o r 6 0 - 10 0 m in .

6 . 8. 6 B l e a c h i n g o f p o l y a c r y l o n i t r i l e w i t h s o d i u m c h l o r i te

Fa br i c s m a de f r om po lya c r y lon i t r i le i n g r e y c ond i t ion ha ve a ye l lowish o r c re a m

t in t . Po lym e r t e x t i le f in ish ing a g e n t s c on ta in ing po lya c r y lon i t r il e a nd n i t ri l e g r oupste nd to ye l lo w dur ing f ib r e p r oc e s s ing a nd re qu i r e s b l e a c h ing [7 0] .



186 B l e a c h i n g o f T e x t i l es

6 . 8. 7 B l e a c h i n g o f p o l y v i n y l a l c o h o l w i t h s o d i u m c h l o r it e

Af te r b o i l ing wi th 1 -2 g/1 o f non- ion ic o r a n ion ic de te r ge n t f o r 45 - 6 0 r a in a t

8 5 - 90 ~ the fa b r i c s r e qur i e b l e a c h ing i f t he y ar e de l ive r e d undye d . The b le a c h ing

c a n be c a r r i e d ou t w i th a so lu t ion c on ta in ing sod ium c h lo r it e , 0 .4 - 0 .7 % ( o .w . f .) ,

pH 3-4 , a t 70-80~ for 30-45 m in .

6 . 8. 8 P r o b l e m o f c o r ro s i o n a n d i ts p r e v e n t i o n i n ch l o r it e b l e a c h i n g

M ost o f the m a te r i a l s u se d in the c ons t r uc t ion f o r b l e a c h ing e qu ipm e n t , a r e

c o r r od e d d ue to f re e c h lo r ine d iox ide ga s e vo lve d du r ing b le a c h in g p r oc e ss . Va r i -

o u s a p p r o a c h e s h a v e b e e n s u g g e s t e d to m i n i m i s e t h e e v o l u ti o n o f c h l o ri n e d i o x i d e

g a s a n d c o r r o s i o n p r o b l e m .(i ) S t a in l e s s s t ee l c on ta in ing 2 .5% m olyb de n um m a ke s the b l e a c h ing e qu ip -

m e n t q u i t e r e s i s t a n t to c h lo r ine d iox ide . T i t a n ium a l so doe s no t c o r r ode in

pres enc e of ch lor i te [71 ] , bu t i ts use i s l im i ted du e to i ts h igh cos t . V esse ls

l ine d wi th t i t a n ium , g l a s s o r c e r a m ic s c a n be use d . F ib r e - g la s s J - B oxe s a r e

su f f i c i e n t ly sm o o th , r e s i s t r e a c t ions w i th c h lo ri t e. C r oss - l inke d po lye s t e r

a nd r e s ins [72 ] u se d in su r f a c e c o a t ings a r e su f f i c i en t ly r e s i s t a n t t o c h lo -

r ine d iox ide .

(i i) C o r r os ion c a n be suppr e s se d v i r tua l ly c om ple te ly by a dd ing se l e c t e d a s -s is tan ts w hich tend "to ha rn ess the f ree evolu t ion of ch lor ine d ioxid e [73] .

The se a s s i s t a n t s a r e those p r oduc t s wh ic h c on ta in n i t r oge n a nd ha ve the

a b i l i ty to s c a va ng e c h lo r ine a nd i t s p r oduc t s . Th e se a s s i s t a n t s r a nge f r om

p r o d u c t s s u c h as a m m o n i u m d i h y d ro g e n p h o s p h at e , s o d iu m a n d a m m o -

n ium n i t r a te (NH4NO3), n i t ri c a c id to n i t roge no us r e s ins suc h a s m e la m ine ,

u r e a a nd o the rs .

(i ii ) Th e p r ob le m s o f c o r r os ion ha z a r d , f um ing a n d f o r m a t ion o f c h lo r a t e a re

a ll m i n i m i s e d w i t h o u t l o ss o f b l e a c h i n g e f f ic i e n c y b y r a is i n g t h e p H f ro m3 to 5 b y m e a n s o f m a g n e s i u m d i h y d r o g e n p h o s p h a t e a c t i v at o r [ 7 4 ].

( iv ) I t i s c l a im e d [75 ] tha t t he sa l ts o f m ono - , d i - o r t r i e tha no la m ine w i ll

m a in ta in a pH o f 7 .0 - 8.5 a t 20 - 50 ~ a nd ye t b r ing a bo u t qua n t i t a tive de -

c om pos i t ion o f c h lo ri t e s a t t e m p e r a tu r e s a bo ve 7 0~

( v) To e l im ina te the c o r r os ion o f the e xpose d pa r ts by c h lo rine d iox ide va pour ,

t h e m a c h i n e s h o u l d b e d e s i g n e d i n s u c h a m a n n e r t h a t c o n d e n s a t i o n i s

p r e ve n te d [76 ] o r by m e a ns o f ga s wa she r i e s wh ic h a re in s t al l e d w i th in the

ve n t i l a t ion duc t w i th w a te r o r a n a lka line hydr oge n pe r ox ide so lu t ion [7 7] .( vi ) C o r r os ion c a n be we l l c on t r o l l e d by the use o f a m m on ium sa lt s , w h ic h






T h e ch lo r i t e b l each in g p r o ces s s u f f e r s fr o m ce r t a in d r aw b ack s a s f o ll o w s :

( i) So d iu m ch lo r it e i s m o r e ex p en s iv e th an h y d r o g en p e r o x id e . It i s n o t u s e -fu l fo r the b leac h ing o f s i lk and woo l , s ince i t g ives p ink co lou ra t ion w hich ,

h o w e v e r , c a n b e r e m o v e d w i t h t re a t m e n t o f s o id u m b i s u lp h i t e s o lu t io n .

( ii ) E v en a t p H 4 - 5 ce r t a in am o u n t o f ch lo r in e d io x id e is ev o lv ed , an d t h e

b l each in g ac t i o n is ex t r em e ly co r r o s iv e t o m e ta l s i n c lu d in g s t a in l e s s s t eel .

N e u t r a l an d a lk a l i n e p H m ay t en d e r th e co t to n .

( ii i) Ch lo r in e d io x id e i s a v e r y t o x i c g as b ecau s e i t c an d eco m p o s e i n to b o th

h y d r o ch lo r i c ac id an d ch lo r in e g as es . T h e g as m ix tu r e i s a s k in i r r i t an t ,

a t t a c k s m u c o u s m e m b r a n e s a n d c a n c a u s e f a t a l p u l m o n a r y e d e m a . T h e

T L V o f t h is co m p o u n d i s 0 .1 p . p . m , an d s h o w s th e n eces s i t y f o r ad eq u a t e

ca r e an d v en t i l a t io n d u r in g u s u ag e .

( iv ) E x p lo s io n s a r e f o s t e red w h e n g as eo u s ch lo r in e d io x id e an d HC1 02 i s ex -

posed to uv l igh t .

6 . 9 B l e a c h i n g w i t h P e r a c e t i c A c i d

P er ace t i c ac id i s an eq u i l i b r iu m s o lu ti o n co n s i s i ti n g o f h y d r o g en p e r o x id e , ace -

t ic ac id an d p e r ace t i c ac id. I t c an b e u s ed f o r b l each in g o f n y lo n , v i s co s e r ay o n ,ce l lu lose ace ta te and even co t ton [79 , 80] . Perace t ic ac id i s commercia l ly ava i lab le

f o r t ex t i le b l eac h in g i n 5, 1 5 an d 4 0% s o lu t io n s a s Wh a t i s k n o w n as "e q u i l i b r iu m

p e r a c i d " . P e r a c e t ic a c i d ca n b e p r e p a r e d b y t h e i n te r a c ti o n o f c o n c e n t r a te d h y d r o -

gen perox ide and ace t ic ac id in the p resence o f s t rong minera l ac id such as su lphur ic

ac id [81 , 82 ]. A l t e r n a t i v e ly , i t c an b e p r ep a r ed b y m ix in g h y d r o g e n p e r o x id e w i th

ace t i c an h y d r id e a t r o o m t em p er a tu r e i n p r e s en ce o f s u i t ab l e ca t a ly s t l i k e cau s t i c

s o d a o r E D T A [ 83 ]. T h e o p t i m u m r e a c t io n t a k e s p l ac e w i th 1 p a r t o f h y d r o g e n

p e r o x id e an d 6 p a r ts o f ace t ic an h y d r id e a f t e r ab o u t 4 h a t r o o m t em p er a tu r e t o g iv e

a y i e ld o f ab o u t 80%. T h e ex ces s ace t i c an h y d r id e m ay , h o w ev e r , cau s e an u n d es i r -

ab l e s i d e r eac t i o n t o y i e ld h ig h ly ex p lo s iv e d i ace ty l p e r o x id e .

H202+ C H 3 C O O H H+ ; C H 3 . C O . O . O H + H 2 0

p er ace t i c ac id

CH3-C=O Cat.O q- H202 @ CH3CO.O.OH + CHgCOOH

[ NaOH

CH3-C=Oace t ic an h y d r id e




The phy s ic a l a nd c he m ic a l p r ope r t i e s o f pe r a c e t ic a c id is sum m e r i se d in Ta b le

6 .5 . The c on c e n t r a t e d so lu t ion o f pe r a c e t i c a c id i s vo la t i le a nd ha s a pun ge n t sm e l lT A B L E 6 . 5

Pr ope r t i e s o f Pe r a c e t i c Ac id

Pr ope r t i e s C on c e n t r a t ion o f p e r a c e t i c a c id

5% 15%

Phys ic a l p r op e r t i e s

Appe a r a nc e

o d o u rp H

De ns i ty ( g /m L , 20 ~

C he m ic a l p r ope r t i e s

H202

Acet ic ac id

2.0

1.120

c o lou r l e s s l i qu id

p u n g e n t2.0

1.480

27 .0 22 .0

6.3 16.6

a nd s t r ong ly i r r it a t es the m uc ous m e m b r a ne . The s t a b i li t y o f pe r a c e t i c a c id is no t

qu i t e h igh a s tha t o f s ta b i l is e d hyd r oge n pe r ox ide . F r e e r a d ic a l s m a y be p r o duc e din the presenc e of ions su ch as copper , i ron e tc .

Perace t ic ac id has prov en to be e f fec t ive b leaching agent in the househ old de te r -

ge n t s a nd a l so f ound w ide a pp l i c a t ion in the l a undr y indus t ry . To r e duc e the da nge r

in the on - s i t e p r oduc t ion o f pe r a c e t i c a c id f r om a c e t i c a nhydr ide /hydr oge n pe r ox-

ide , ac t iva tors can be used in household de te rgents to genera te pe race t ic ac id in

s i tu . The c om m only use d a c t iva to r s a r e sod ium pe r bor a t e a nd a c e ty la t e d 0 o r N-

c om pounds suc h a s t e t r a a c e ty le thy le ne d ia m ine ( TAED) [8 4 , 8 5 ] . The pe r bor a t e

ac t iva to rs a re assu m ed to ac t v ia the s tages of pe race t ic ac ids [86 ] . Pe rbora te h y-

d r o lyse s in a que ous so lu t ion a nd hyd r oge n pe r ox ide i s p r oduc e d . R e a c t ive pe r ox -

i d e an i o n i s p r o d u c e d f r o m h y d r o g e n p e r o x i d e u n d e r w e a k l y a l k al in e m e d i u m a n d

Na4(H4B2Os) + 4H 20 --+ 2Na2[B(OH)4 ] + 2H202

H202 + O H- --~ H O 2- 4- H 20

X - A c + HO 2- ~ X - + A c O O H

t he n the a c tiva to r re a c t s [8 7 ]. The c he m is t r y o f TA ED /H20 2 b le a c h in g i s ba se d on

t he f o l lo w i n g m e c h a n i s m :








( iv ) Pe r a c e t ic a c id b l e a c he d goo ds show c om pa r a b le o r e ve n h ighe r b r ighm e ss

wi th le ss f ibre damage .(v) In the hou sehold pow der de te rgent , pe race t ic ac id i s genera ted in s i tu f rom

activators .

The d i sa dva n ta ge s o f pe r a c e t i c a c id a s a b l e a c h ing a ge n t ar e :

( i) Co ncen t ra ted so lu t ion ofp erac e t ic ac id (35-40% ) is dang erous ly explos ive

a nd c a nno t be ha nd le d . The c o nc e n t r a t e d so lu t ion ha s a pun ge n t odour , i s

caus t ic and burns the sk in . I t needs to be ca r r ied in spec ia l ly pro tec ted

ta nke r wa g ons w he n t r a nspor t e d b y ra i l.

( ii ) I t i s expe ns ive for b leac hing of co t ton and rayon and is used on ly as a la s t

resor t .

( ii i) The s tab i li ty ofpe race t ic ac id i s not qui te h igh as tha t of s tab i l i sed h ydro gen

pe r ox ide . F r e e r a d ic a l s m a y be p r oduc e d in the p r e se nc e o f C u a nd Fe

ions.

6 .1 0 R e d u c t i v e B l e a c h i n g o f W o o l

R e d u c t i v e b l e a c h i n g t r e a t m e n t s a r e n o r m a l l y e m p l o y e d f o r t h e b l e a c h i n g o f

woo l , s i l k and ny lon f ib r es . Now - a - da ys , t he m a in f o r m o f r e duc t ive b l e a c h in ge m p loys hydr osu lph i t e c om pou nds . T he t r ea tm e n t s u s ing su lphur d iox ide o r sod ium

bisu lph i t e a r e now on ly o f h i s to r i c a l va lue a s the p r oc e ss ha s m a ny p r a c t i c a l

d i sa dva n ta ge s . S od ium hy dr osu lph i t e m a y be used a lone, p r ov ide d the t e m pe r a tu r e

of the b leach ba th i s kept low to preve nt rap id decom posi t ion . How ever , a s tab i l i sed

f o r m o f s o d i u m h y d r o s u l p h i te i s m o r e c o m m o n l y u s e d , in w h i c h t h e in c l u s io n o f

sod ium pyr ophospha te ( o r o the r non- phospha te bu f f e r s ) c on t r o l s t he pH c lose to

ne u t r a l t o inh ib i t the too ra p id de c om pos i t ion o f the hydr osu lph i t e. B y the use o f

s u c h s t a b i li s e d h y d r o s u l p h i t e c o m p o u n d a m u c h h i g h e r t e m p e r a t u r e c a n b e

e m ploye d . Th iou r e a d iox ide i s som e t im e s e m ploye d a s a r e duc ing a ge n t f o r t he

b le a c h ing o f woo l [9 3 -9 5 ] . The de c o m p os i t ion r a t e o f t h iou r e a d iox ide inc r e a se s

wi th inc r e a s ing pH a nd t e m pe r a tu r e a nd de c r e a se s w i th inc r e a s ing c onc e n t r a t ion

[96].

6 .10.1 B leach ing o f woo l w i th su lphur d iox ide ( s tov ing proce s s )

I n th i s m e tho d m ois t woo l l e n ya r n in the ha nk f o r m i s e xpose d to the a c t ion o f

su lphur d iox ide p r o duc e d by bu r n ing su lphur ( 3 to 6 % o .w . f .) p l a c e d in a n i r on o re a r the nw a r e po t i n s ide the c ha m be r . S u lphur i s c onve r t e d to su lphur d iox ide a nd




su lphur ous a c id ga s in the p re se nc e o f m o i s tu r e. S u lphur ous a c id is a s t r ong r e duc ing

a g e n t w h i c h r e d u c e s t h e o r g a n i c c o l o u r i n g m a t t e r in t o c o l o u r le s s s u b s t a n c e s . T h e

m a te r i a l i s e xp ose d to su lphur d iox ide f o r 6 to 8 h o r ove r - n igh t a nd the n r in se d f o r

15 m in in H20 2 ( 0 .1% ) so lu t ion a t 35~ w h ic h ox id i se s r e t a ine d su lphur d iox ide

( p r e se n t a s su lphur ous a c id ) to su lphur i c a c id a nd f ina l ly ne u t r a l i s e d wi th d i lu t e

su lphur i c a c id a nd b lue d . P ie c e goods in m oi s t c ond i t ion c a n a l so be s tove d in a

s im i l a r m a nn e r by pa s s ing th e m in to the s tove th r ough a na r r ow s l it in the s tove a nd

susp e nd ing on wo ode n r o l le r s a r r a nge d in two t i re s .

T h e d i s a d v a n t a g e s o f t h is m e t h o d a r e :

(i ) B le a c h in g e f fe c t i s no t pe r m a ne n t , t he na tu r a l c o lou r o f wo o l r e tu r ns

gradua l ly .

(i i) The su lphu r ous a c id ga s m a y be f o r m e d by the r e a c t ion o f S O 2 a nd wa te r ,

w h i c h c a n c a u s e p e r m a n e n t d a m a g e t o e y e s an d re s p i r a to r y s y s te m .

(iii) E v e n a f t e r t h o r o u g h w a s h i n g w o o l r e ta i n s s u l p h u r d i o x i d e a n d h e n c e

t r e a tm e n t w i th ox id i s ing a ge n t l i ke NaOC 1 o r H20 2 i s ne c e s sa r y .

( iv ) The p r oc e ss r e qu i r e s long e r t im e f o r b l e a c h ing .

(v) I f w oo l is too dry , the b le ach ing e f fec t i s poor .6 .1 0 .2 B l e a c h i n g o f w o o l w i t h s o d i u m b i s u l p h i t e

I n the sod ium b i su lph i t e m e thod [9 7 ] , woo l i s im pr e gna te d wi th a so lu t ion

c o n t a i n i n g 2 ~ s o d i u m b i s u l p h i te a n d 1~ HzSO 4 f o r 2 h . A l t e r na t ive ly , w oo l

c a n be t r e a t e d wi th a so lu t ion o f sod ium b i su lph i t e (2~ f o r 6 to 10 h , sque e z e d ,

a n d i s t h e n f o l l o w e d b y s e c o n d im p r e g n a t i o n in H z SO 4 ( l ~ a n d w a s h e d

tho r ough ly .

6 . 10 .3 B l e a c h i n g o f w o o l w i th s o d i u m h y d r o s u l p h i t e

R e d u c t i v e b l e a c h i n g w i t h n o n - s t a b i l i s e d s o d i u m h y d r o s u l p h i t e [ 9 8 ] , s o d i u m

h y d r o s u l p h i t e - b a s e d s u l p h o x y l a t e f o r m a l d e h y d e [ 9 9 ] a n d s o d i u m a n d z i n c

h y d r o x y m e t h a n e s u l p h i n a t e [ 1 0 0 ] h a v e b e e n s h o w n t o p r o v i d e w o o l e x c e l l e n t

w h i t e n e s s , w i t h a l o w e r c y s t i n e c o n t e n t t h a n i n th e c a s e o f b le a c h i n g w o o l w i t h

o the r r e duc in g a ge n t s . The r e su l t ob ta ine d i s pe r m a ne n t , i n c on t r a s t to the uns t a b le

p e r o x i d e w h i t e .

The good s a r e t r e a t e d wi th a so lu t ion c on ta in ing sod ium hyd r osu lp h i t e ( 4 - 8 g /l )

o r s t a b i l is e d sod ium hyd r osu lph i t e ( 5 - 10 g / l) a nd py r oph osph a te o r bu f f e r ( 3 - 4 g /l )a t 50 - 55~ f o r 1 -2 h . S od ium hydr o su lph i t e in a que o us so lu t ion i s c onv e r t e d in to

sod iu m b i su lph i t e whe n a pp l i e d at 50~ a t pH a r oun d 7.0 . Af te r b l e a c h ing the




g o o d s a r e r i n s e d i n w a r m w a t e r a n d t h e n i n c o l d . T h e p r e s e n c e o f s o d i u m

la ur y l su lph a te ( S L S ) in the b l e a c h ing ba th im pr ove s the wh i t e ne ss a nd m e c ha n ic a lp r op e r t i e s o f t he b l e a c he d good s w i thou t a f f e c t ing the c y s t ine c on te n t [ 101 ] . The

pr o te c t io n i s the ou tc o m e o f su lph i to lys i s i nh ib i t ion de r ive d f r om the ion ic o r non-

ionic in te rac t io n of SLS in the po s i t ive s i te s ofke ra t in e ( -NU3 +) or in the pa ra f f in ic

s ide c ha ins o f s a m e a m ino a c id r e s idue s . The in t e r a c t ion o r c om bina t ion o f S L S

w i th p r o te in inc r e a se s i t s ne t ne ga t ive c ha r ge a nd h inde r s the a c c e s s o f the r e duc ing

a ge n t to the d i su lph ide l i nka ge [10 2 ]. I ron a nd c opp e r in the hydr osu lph i t e b l e a c h

ba th c a n c a use a g r e y i sh d i sc o lou r a t ion due to the f o r m a t ion o f the i r r e spe c t ive

su lph id e s w h ic h a r e d i ff i c u l t t o r e m ove du r ing wa sh ing .

6 . 1 0. 4 B l e a c h i n g o f w o o l w i th t h i o - u r e a d i o x id e

T h e o p t i m u m b l e a c h i n g v a l u e o f w o o l c a n b e a c h i e v e d a t t h i o - u r e a d i o x i d e

1 .5 g /l , t im e 30 m in a nd t e m p e r a tu r e 8 0 ~ The c os t o f b l e a c h ing wi th th io - u r e a

d iox id e i s c l a im e d to be th r e e t im e s l e s se r t ha n tha t o f b l e a c h in g c a r r i e d ou t w i th

sod iu m hy dr osu lph i t e . A l so , it s l a c k o f m u ta ge n a c t iv i ty a nd i ts low C OD a nd

B O D v a l u e s r e c o m m e n d e d i t a s a n o n - t o x i c p r o d u c t g i v in g a l o w c o n c e n t r a t io n o f

e f f luents .6 .1 0 .5 P h o t o b l e a c h i n g o f w o o l

T h e n o v e l m e t h o d o f b l e a c h i n g w o o l b y e x p o s u r e t o i n te n s e l i g h t ar e a t tr a c ti v e

b e c a u s e o f th e d r y a n d p o l l u t io n - f r e e n a t u r e o f t h e p ro c e s s . P h o t o b l e a c h i n g c a n b e

rapid an d the resul t ing colou r and br ighmess a re s imi la r to those of pe roxide b leached

w o o l [ 1 0 3 ] . T h o u g h p h o t o c h e m i c a l b l e a c h i n g i s i n d u s t r i a l l y p o s s i b l e , b u t n o t

e c o n o m i c a l l y a t t r a c t i v e y e t . W o o l c a n b e p h o t o c h e m i c a l l y b l e a c h e d [ 1 0 4 ] b y

e xp osu r e to u .v. l i gh t be low 36 0 nm . W he n w oo l i s t r e a t e d wi th a z inc c om ple x o f

t h i o g l y c o l l ic a c id t o m i n i m i s e y e l l o w i n g a n d t h e n e x p o s e d t o s u n l ig h t , u n d e r g o e s

pho toc he m ic a l b l e a c h ing w h ic h e f f e c t ive ly de s t roys the im pur i ti e s c a use d by pho to -

de gr a da t ion .

6 .1 1 B l e a c h i n g o f S il k w i t h R e d u c i n g A g e n t s

S i lk f ib r ion i s h igh ly se ns i t ive to ox id i s ing a ge n t s l ike hypo c h lo r i t e a nd c h lo r i te

so lu t ions . O x ida t ion a nd sub s t i tu t ion in the be nz e ne r ing o f ty r os ine i s r e spon s ib le

f o r de g r a da t ion o f s i lk w i th the fo r m a t ion o f c h lo r o - a m ino a c ids , ke ton ic a c ids a nd

r in severa l s tages [105] .R e d u c t i o n b l e a c h i n g o f s i lk i s g e n e r a ll y c a r r ie d o u t w i th s o d i u m h y d r o s u l p h i t e

o r a pp r opr i a t e s t a b i l i s e d c om m e r c ia l p r oduc t s on th i s ba s i s . The s i lk f ib r ion i s




r e s i s t a n t t o the r e duc ing a ge n t s . S inc e the b l e a c h ing e f f e c t i s poor e r tha n wi th

p e r o x i d e b l e a c h , t h e t e r m " h a l f b l e a c h " i s s o m e t i m e s u s ed . A b r i e f r e s u m e o f t h eT A B L E 6 . 6

B l e a c h i n g o f S i lk w i t h R e d u c i n g A g e n t s

R e d u c i n g a g e n t C o n d i t i o n

S u lph ur d iox ide o r 4 to 6 h a t a n a tm o sphe r e o f S O 2,

S u lph ur ous a c id . ye l low ish t in t ob ta ine d .

S od ium hyd r osu lph i t e . 4 to 6 h a t t e m pe r a tu r e a r oun d 50 ~

N a 2 S 2 0 4 + 4H202 --> 2 N a H S O 4 + 3H 2 pH 7 , c onc e n t r a t ion a r o und 45 g /1 .S ta b i l i s e d hydr osu lph i t e . 30 to 9 0 m in a t t e m p e r a tu r e o f 6 0 -9 0 ~

S o d i u m s u l p h o x y l a te s .

NaHSO2.CH20 + H20 --> NaHS O3 + H2

pH 5 to 7 , con cen t ra t ion a rou nd 10 g /1 .

C o nc e n t r a t ion 4 to 6 g / l, t e m pe r a tu r e

60-95~ pH 4 to 5 .5 , t ime 20-30 min .

b le a c h ing o pe r a t ions i s h igh l igh te d in Ta b le 6 .6 .

S om e t im e s s i lk i s st il l b l e a c h e d w i th su lphur d iox ide in ga s f o r m . To do th is t he

dam ped fabr ic i s subjec ted to the su lph ur d ioxide gas for severa l hou rs in an enc losed

c h a m b e r . T h r o u g h t h e f o r m a t i o n o f s u l p h u r d i o x i d e s o m e n a t u r a l d y e s t u f f s a r e

r e duc t ive ly de s t r oye d , whe r e a s o the r s a r e on ly c onve r t e d to wa te r so lub le l e uc o

c o m p o u n d s , w h i c h t h e n h a v e t o b e w a s h e d o u t, s o a s n o t t o r i s k r e o x i d a t i o n a n d

t h u s y e l l o w i n g d u r i n g s t o r a g e. T h e f r eq u e n t l y n o t i c e d u n p l e a s a n t o d o u r o f t h e

r e m a in ing su lphur d iox ide on the f ab r i c c a n be e l im ina te d by a r in s ing p r oc e s s w i th

hy dr o ge n pe r o x ide o f 35% s t r e ng th (1 m g/1 ).

I f a v e r y h i g h d e g r e e o f w h i t e n e s s i s r e q u i r e d , a d o u b l e b l e a c h p r o c e s s i sr e c o m m e nd e d . He r e b l e a c h ing i s c a r r i e d ou t on two se pe r a t e s t a ge s , fi rs t the s i lk i s

t r e a t e d wi th 3 to 5 g /1 s t a b i l i s e d sod ium h ydr o su lph i t e a t 6 0~ f o r 1 h , f o l lowe d by

ox ida t ive b l e a c h ing us ing H2 0 2 , 10 -20 m l /1 ( 35% s t r e ng th ), 2 - 3% sod ium s i li c a te ,

the pH o f the ba th be ing m a in ta ine d a t 8 .5 - 9 .0 a t 9 0~ f o r 1 h . W i th th i s p r oc e ss , a s

a ro le , an exc e l len t fu ll whi te i s achieved, w hich w i l l endure s torage and i s lightproof .

C e r t a in tu s sa h s i lk s c a nno t , how e ve r , be b l e a c he d to a fu l l wh i t e , e ve n a pp ly ing th is

pro ces s [ 106] .

6 .1 2 R e d u c t i v e B l e a c h i n g o f Ny l o n

R e d u c t i v e b l e a c h i n g o f n y l o n i s n o r m a l l y e m p l o y e d u n d e r a c i d ic c o n d i t i o n s .




Vir tu a l ly no f ibre deg rada t ion occurs and the res is tance of the f ibre to pho to-

de gr a da t ion i s no t im pa i r e d . The l iquor i s s e t w i th 2 - 4% ( o .w . f . ) s t a b i l i s e dhydrosulphi te , 2% (o .w. f . ) seques te r ing agent , 0 .2-1% (o .w. f . ) se lec ted f luorescent

b r igh te ne r a nd a c e t i c a c id to pH 4 .5 . The g oods a r e e n te r e d in to the ba th a nd the

te m pe r a tu r e i s r a i s e d s lowly (1 ~ to 8 5 -10 0~ Tr e a tm e n t i s c on t inue d un t il

t he de s i r e d c o lou r i s a c h ie ve d . The goods a r e the n c oo le d a nd r in se d tho r ough ly .

6 .1 3 P ero x y g en B l ea c h i n g C o m p u n d s

The r e a r e s e ve r a l pe r oxyge n de r iva t ive s tha t oc c a s iona l ly f ind use in t e x t i l e

indus t ry . The se a re po ta s s ium pe r oxym onos u lpha te ( m onope r su lpha te ) , po ta s s ium

pe r pho spha te a nd u r e a pe r ox ide . The se c om poun ds a re r a r e ly use d by the m se lve s ,

bu t a r e u se d p r im a r i ly a s b l e a c h boos te r s . The y a r e a l l powde r s a nd a r e u sua l ly

c om poun de d whe r e a s tr ong c o lou r l es s ox id i s ing a ge n t is ind ica te d . The m e c h a n i sm

of po ta s s ium pe r oxy d i su lpha te pe r ox ide i s r e p r e se n te d by the f o l lowing r e a c t ions ;

82082 . ~ 28 04 - "

SO4-o -}- H 2 0 ~ H + + 8042- "ol-O H "

O H " + H202 --~ H2 0 + HO 2"

H O 2" + 82082- ~ 02 q-- HSO4-+ SO4-"HO 2" + H202 ~ 0 2 q- H 2 0 + O H "

to g ive a ne t r eac t ion

82082-q - H2 02 ---> 02 -it- HS O4 -

Above pH 5 .0 , the addi t ion s teps a re wr i t ten :

H O 2" @ O 2- + H +

0 2 - + 8208 ~ 02 -1- 8042 - q SO 4-

O 2- q- H2 02 ~ 02 -1- O H + O H "

U n d e r t h e n a m e o f " O x o n e " D u P o n t h a s p u t on t h e m a r k e t a b l e a c h i n g a g e n t

f o r po lya m ide f ib r e s . I t s a c t ive b l e a c h ing c om pone n t i s po ta s s ium pe r su lpha te

(KHSO s, pH of a 1 .0% solu t ion i s 2 to 3). Oxon e i s used for the b leach ing of nylon ,

toge the r w i th Na C 1 a nd a m ix e d bu f f e r K2CO 3 a nd Na H2PO4.2H20 a t pH be tw e e n

7 .5 and 8 .0 a t 80~ This b lea chin g auxi l ia ry is used m ore for dom est ic b leachin g

tha n f o r b l e a c h ing f in ish wor ks .

6 .14 B leach ing o f Jute

The a r t of b leaching ju te has rece ived f resh a tten t ion as d ive rs i f ied ju te pro duc ts

l ike de c o r a t ive s , so f t l ugga ge , a nd up ho l s t r y m a te r i a l a r e in g re a t de m a n d no w- a -

da ys . R a w I nd ia n ju t e i s b r ow n in c o lou r a nd r e qu i r e s b l e a ch ing . S c o r u ing o f ju t e



Bl each i n g o f T ex t i le s 197

fabr ic before b leach ing has no benef ic ia l e f fec t , ra ther i t de te r io ra tes whi teness

index . The g rey ju te fabr ic a t t a ins redd i sh tone a f t e r scour ing in a lka li . How eve r ,

s co u r i n g o f j u t e f ab r ic b e fo re s o d i u m ch l o r it e b l each i n g en h an ces t h e w h i t en es s

index . A da m age to the ju te f ib re occurs a t concen t ra t ions o f caus t ic sod a h igher

than 9 .0% [ 107] . Bleac h ing re nde rs ju te ne ar wh i te resu l t ing in be t t e r lus t re and

ap p ea l t o t h e f ab r ic . B l each i n g o f j u t e i s a ls o r eq u i r ed fo r g o o d co l o u ra t i o n

b ack g ro u n d .

B l each i n g o f j u t e can b e a f f ec ted b y a l l b l each i n g ag en t s , b u t b l each i n g p o w d er

an d h y d ro g en p e ro x i d e [ 1 08 ,1 09 ] f i n d co mmerc i a l ap p l i ca t i o n . O w i n g t o t h e

p r e s e n c e o f n o n - c e l l u l o s i c c o n s t i tu e n t s , p a r t i c u l a r l y l ig n i n , t he a c t i o n s o fcon ven t iona l b lea ch in g ag en t s such as H202 , NaC102, perac e t i c ac id and NaOC1

are s o mew h a t d i f f e r en t a s co mp ared t o t h e i r a c t i o n o n co t t o n [ 1 1 0 ,1 1 1 ] . T h e

b leac h ing ef fec t o f H202 and perace t i c ac id on l ign in i s a lm os t n i l. The u se o f

s o d i u m h y d ro s u l p h i t e , s o d i u m b i s u l p h i t e , s o d i u m b o ro h y d r i d e h av e a l s o b een

reco m m en d ed fo r b l each i n g o f j u t e [ 1 12 ]. J u te b l each ed w i th r ed u c i n g ag en t s is n o t

a l l s t ab le and develops redd i sh o r b rown t inge on s to rage .

6 .14 .1 B l each ing o f ju te wi th sod ium hypo ch lor i t e

Ju te p iece goo ds a re b leache d in open w id th e .g. on j igs and ju te carpe t yarn i sb l each ed i n h an k fo rm o r i n t h e fo rm o f c ro s s -w o u n d ch ees es i n an o p en m ach i n e .

Ju te can be b leached wi th a lka l ine hypoch lor i t e us ing 5 -7 g /1 ava i l ab le ch lor ine .

A f t e rw ard s t h e g o o d s a r e u s u a l l y g i v en an an t i ch l o r w i t h s o d i u m b i s u l p h it e , b u t i t

i s n o t s o u red b ecau s e o f th e d i f f icu l t y o f r em o v i n g t h e t races o f aci d . H o w ev e r , t h e

s o d i u m h y p o ch l o r i t e b l each i n g p ro d u ces p o o r w h i t en es s w h i ch i s n o t accep t ab l e

fo r s u b s eq u en t d y e i n g an d p r in t in g .

6 .14 .2 B l each in g o f ju te wi th hyd rogen perox ide

H y d ro g en p e ro x i d e b l each i n g p ro ces s i s mo s t s u i tab le fo r b l each i n g j u t e f ab r ic s

an d t h e b l each ed g o o d s a r e s u i t ab le fo r m ak i n g d i v e r s if i ed j u t e p ro d u c t s .

Blea ching exclusively wi th hydrog en peroxide in the presence of s il icate general ly

n eces s i t a t e s h i g h p e ro x i d e co n s u mp t i o n l ev e l an d r i g o ro u s co n d i t i o n s an d h en ce

s u b s t an t ia l f i b r e d am ag e can r e s ul t. B l each i n g o f g r ey j u t e can b e ca r r i ed o u t w i t h

H202 (2 vol .) , sod ium s i l icate (10 g/l) , sodium hyd roxide (1 g/ l) , t r i sodium p hosp hate

(5 g /l ), pH arou nd 11 a t 80~ fo r about 1 h . Af te r b leach ing the fabr ic is thorou ghly

w as h ed , n eu t r a l i s ed w i t h 2 m l /1 ace t ic ac i d an d t h en u s u a l w as h i n g an d d ry i n g i s

ca r r ied o u t . A l k a li n e h y d ro g en p e ro x i d e g i v es a g o o d w h i te co l o u r an d l e s s mark ed

y e l l o w i n g t h an t h a t o fh y p o ch l o r i t e b l each . T h e l o ss e s i n s tr en g t h an d w e i g h t d u e t o



198 Bleac h in g o f T ex t i l e s

b l eac h in g t r ea tm en t a r e a l so l es s in ca se o f p e r o x id e b l ea ch in g p r o ces s , co m p ar ed

to h y p o ch lo r i t e b l each .

Process invo lv ing on ly use o fH202 i s no t very su i tab le as above cer ta in percen tage

o f H202 (6% o f 5 0% H2 02 ) co n ce n t r a t i o n , t h e r e i s n o ap p r ec i ab l e i n c r eas e i n

b r ig h m es s v a lu e . Mo d i f i ed b l eac h in g r ec ip es f o r j u t e a r e n o w b e in g r ep o r t ed [ 1 1 3,

1 1 4 ] . J u t e w i th h ig h l i g n in co n t en t co m p ar ed w i th o th e r ce l l u lo s i c f i b r e s , c an b e

b l eac h ed i n a s eq u en t i a l p r o ces s u s in g s o d iu m ch lo r it e o r h y p o ch lo r i te f o l l o w ed b y

hyd roge n perox ide - sod ium s i li ca te b leach to p roduce the bes t f ib re wh i teness wi thou t

ap p r ec i ab l e s t r en g th l o ss . L ig n in p r e s en t i n j u t e i s ch lo r in a t ed t o co n v e r t i n to

ch lo r o l i g n in w h ich a r e f u r th e r ex t r ac t ed d u r in g a lk a l i n e ex t r ac t i o n . T h i s i s t h enf o l l o w e d b y p e r o x i d e b l e a c h i n g . T h e w h i t e n e s s c a n f u r t h e r b e r a i s e d b y t h e

app l ica t ion o f a su i tab le f luorescen t b r igh ten ing agen t to the b leach ba th o r sepera te ly .

6 . 1 4 .3 B l e a c h i n g o f j u t e w i th s o d i u m c h l o r i te

Sco u r in g an d b l each in g o f ju t e w i th s o d iu m ch lo ri te w i th an accep t ab le w h i t en es s

can b e ach i ev ed , b u t th e p r o ces s i s a t im e co n s u m in g tw o s t ep p r o ces s . M o r eo v e r ,

s o d iu m ch lo r i te i s m e ta l co r r o s iv e an d h ea l t h h aza r d o u s .

A s in g l e s t ag e p r o ces s co n t a in in g 5 % s o d iu m ch lo r i te s o lu t io n a t 65 - 70~ w i th

a l i q u o r r a t i o o f 1 0 : 1 can p r o d u ce p a l e y e l l o w co lo u r , w i th m o d er a t e ly g o o d w e ts t r eng th , bu t the f abr ic i s m ined ye l low on exp osure to l igh t [ 115] . In ano ther a t tem pt ,

t r ea tm en t o f j u t e w i th 3 g/1 s o d iu m ch lo r it e a t b o i l f o r 90 m in a t p H 4 an d t h en

f o l l o w e d b y t r ea tm en t w i th H2 02 (0. 5 v o l .) s o lu t io n b u f f e r ed t o p H 1 0 a t 80~ f o r

3 0 m in , g iv es a p r o d u c t w i th co m p ar a t i v e ly im p r o v ed w h i t en es s an d r e s i s t an ce t o

y e l l o w in g o n ex o s u r e t o l i g h t [ 1 1 6] . A d i r ec t b l each in g p r o ces s [ 1 1 7 ] b y t h e u s e o f

a s o lu t i o n co n t a in in g s o d iu m ch lo r i t e , h y d r o g en p e r o x id e a s a s t ab i l i s e r f o r t h e

ch lo r i t e , an d b u f f e r s a l t s s u ch a s m o n o - an d d i - s o d iu m p h o s p h a t e (5 0 - 2 5 0% b as ed

on ch lor i te con ten t ) a t pH 4 .5 -7 i s a l so r epor ted . The f abr ics a re wrung ou t to

r em o v e ex ces s l i q u id , a re h ea t ed b y m ea n s o f a su p e r h ea t ed s t eam an d a r e k ep t a t a

t em p er a tu r e o f 90~ f o r 3 h . T h e w h i t en es s o f t h e f ib r e is u n i f o r m an d o f a h ig h

s t an d a r d . A m in im u m ch an g e i n t h e DP o ccu r s w h en th e j u t e i s b l each ed w i th 0 . 7%

s o d iu m ch lo r i te a t p H 4 an d 65 -70~ f o r 80 m in . T h e r a te o f b l each in g can b e

in c r eas ed b y i n c r eas in g t h e t em p e r a tu r e [ 1 1 8] .

6 . 1 4 .4 B l e a c h i n g o f j u t e w i t h p e r a c e t i c a c id

T h e u s e o f p e r a ce t i c ac id a s a b l each in g ag en t f o r j u t e f ab r ic s i s r ep o r t ed [1 1 9 ].

T h e o p t im u m b l each in g r e s u l ts a r e o b t a in ed a t 70~ a r o u n d p H 6.5 . T h e m i ld ac id ic

co n d i t i o n i s m o s t s u i t ab l e b ecau s e o f t h e f act t h a t n e i t h e r h y d r o ce l l u lo s e n o r



B l e a c h i n g o f T e x t i l es 199

oxyc e l lu lose i s p r oduc e d a t t h i s pH . Pe r a c e t i c a c id b l e a c h ing i s m or e e f f e c t ive in

r e d u c i n g l o s s e s i n w e i g h t a n d t e n s i le s t re n g t h t h a n h y d r o g e n p e r o x i d e b l e a c h i n g .

T h e i m p r o v e m e n t i n h a n d l e s /f e e l a n d l o w a s h c o n t e n t o f p e r a c e ti c a c i d b l e a c h e d

jute fabr ics is a t tr ibuted to s i l ica te f ree bleachin g. Jute can a lso be effec t ively bleach ed

with pe rac e t ic ac id in the presen ce o f se lec ted buf fe r ing and s tab i l i s ing agents [ 120].

A s u p e r i o r b l e a c h i n g e f fe c t c a n b e a c h i e v e d b y u s i n g t e tr a s o d i u m p y r o p h o s p h a t e

( TS PP) a s a s t a b i l i s e r und e r m i ld ly a lka l ine c ond i t ions ( pH 8 .0 -8 .5 ) a nd e xc e l l e n t

f ib re b r igh tne s s c a n oc c u r a t t e m pe r a tu r e s a s low a s 40 - 6 0~ Th i s p r oc e ss o f f e rs a

m or e e ne r gy e f f i c i e n t op t ion f o r b l e a c h ing 10 0 % ju te f a b r ic . Th i s p r oc e ss c a n a l so

b e e x t e n d e d t o b l e a c h i n g o f j u t e / c o t to n b l e n d s .6 .1 4 .5 D r a w b a c k s i n b l e a c h i n g o f j u t e

T h e r e a r e s o m e s e r i o u s d r a w b a c k s w i th r e fe r e n c e t o th e b l e a c h in g o f j u t e . T h e y

a r e :

(i ) Ju t e f a b r ic b l e a c h e d wi th a lka l ine hyp oc h lo r i t e s o r hyd r oge n pe r ox id e

u n d e r g o e s m a r k e d l o s s es i n w e i g h t a n d s t r en g t h a n d a l so s h o w s d e c r e a s e

in w id th . Th e se a r e m a in ly a t t r ibu te d to the a c t ion o f b l e a c h ing a ge n t o r

a lka l i o r a lka l ine r e a ge n t s on the non- c e l lu los i c c ons t i tue n t s o f j u t e i .e .,

h e m i - c e l lu l o s e a n d l ig n i n [ 1 2 1 , 1 2 2 ] .

(i i) Th e he a vy de pos i t s o f c a l c ium o r m a gn e s ium s i l ic a t e on the su r f a c e o f the

f a b r ic , r e su l t ing f r om pe r ox ide b l e a c h in g w i th s i li c a te , p r oduc e ha r sh f e e l

a nd p r e se n t d i f f i c u l t ie s in subse q ue n t p r oc e ss ing .

(iii) T h e m a i n d r a w b a c k o f h y p o c h l o r i t e o r p e r o x i d e b l e a c h e d ju t e is

p h o t o y e l l o w i n g . T h e r e a s o n f o r y e l l o w i n g i s e n v i r o n m e n t a l e f f e c t s l i k e

he a t , a i r , uv r a d ia t ion in sun l igh t e t c . On e xposu r e to l i gh t , t he sha de o f

b l e a c h e d j u t e t u rn s t o b r o w n i s h y e l l o w , w h i c h r u i n s t h e d e c o r a t iv e l o ok .T h i s y e l l o w - b r o w n c o l o u r c a n b e r e m o v e d b y s e c o n d b l e a c h in g t re a t m e n t ,

bu t i t a ppe a r s on f u r the r e xpo su r e to li gh t. The on - se t o f ye l low ing v a r i e s

c o n s i d e r a b l y w i t h t h e b l e a c h i n g a g e n t u s ed .

6 .14 .6 C auses of ye l lowing and impro veme nt of photos tabi l i ty of b leached jute

Ju te ha s th r e e m a in c om pon e n t s c ~ -c el lu lose ( 6 0%) , he m i - c e l lu lose ( 24%) a nd

l ign in ( 13%) . The f i r s t two c om pone n t s do no t a bso r b uv - r a d ia t ion p r e se n t i n the

sun- l ight (300-400 nm) , l ignin how ever does . The reac t ion i s be l ieved to be ox ida t ive

in na tu r e a nd he a t a nd oxyge n in the a i r c a use pho to - se ns i t i z a t ion o f l i gn in . Th i s

d i sc o lou r a t ion i s a l so a s soc ia t e d wi th lo s s o f s t r e ng th . The de g r a da t ion o f l i gn in



2 00 Bleac h in g o f T ex t i l e s

m a y b e a s s o c i a te d w i t h th e p r o d u c ti o n o f si m p l e r a r om a t i c c o m p o u n d s h a v i n g t w o

phen ol ic funct ional g roups , o r a pheno l ic and an a ldehyd e funct ional g roup a t tache d

t o t h e n u c l e u s . T h e c o m p o u n d s t h e n a p p e a r t o u n d e r g o c o n d e n s a t i o n r e a c t i o n s

invo lv ing a fr ee r ad ica l m echan ism. In th i s p rocess , chrom opho re g rou ps are fo rm ed

w i th q u in o n e - m e th id e t y p es o f st r u c tu re s , an d th es e a r e r e s p o n s ib l e f o r y e l l o w in g .

T h e im p r o v em en t o f p h o to s t ab i l i t y o f ju t e f ab r i c i t s e l f i s an im p o r t an t m a t t e r to

b e g i v e n p r i o ri ty . V a r i o u s p r o c e s s e s h a v e b e e n d e v e l o p e d i n w h i c h b l e a c h e d j u te

d o es n o t r ev e r t t o i ts n a tu r a l co lo u r o n ex p o s u r e t o l ig h t . T h e b lo ck in g o f r eac t i v e

phen ol ic g roup s by e ther i fica t ion o r es te ri f ica t ion i s expected to a r res t the ye l low ing

p r o c e s s . T h e p r e s e n c e o f s o m e c h r o m o p h o r e i n d y e s c a n c a u se a b s o r p t i o n o f n e a ru v - r ad i a t i o n o f s u n l ig h t an d p r ev en t d i s co lo u r a t i o n . B leach ed j u t e g o o d s t r ea t ed

w i th co p p e r - p o t a s s iu m d i ch r o m a te (0 . 2 5 % o . w . f . ) im p r o v e p h o to s t ab i l i t y o v e r

co n v en t io n a l b l each ed f ab ri c [ 1 23 ] .

B l e a c h i n g o f j u t e w i t h H 2 0 2 f o l lo w e d b y t r e a t m e n t w i th a n a q u e o u s s o l u ti o n o f

p o t a s s iu m p e r m an g an a t e (8 - 1 2 % o . w . f .) an d a m in e r a l ac id , H2 SO 4 (8 - 1 2 % o . w . f .)

i s r eco m m end ed [ 124] . Subsequen t ly , the r educed pe rman ganate i s c leared by rins ing

th e f ab r i c i n an aq u eo u s s o lu t i o n o f s o d iu m b i s u lp h i t e o r s o d iu m s u lp h o x y la t e

f o r m a ld eh y d e a t p H 3 . 0 -3 . 5 . An o th e r p r o ces s [ 1 2 5] co n s i s ts i n b l each in g o f j u t e

f ab r ic a t a p H b e lo w 3 . 0 an d a t em p er a tu r e i n t h e r an g e 1 5 -4 3 ~ in an aq u eo u s

s o l u ti o n o f p o t a s s i u m p e r m a n g a n a t e a n d p h o s p h o r ic a c id i n a m o u n t s s u c h t ha t th e

r a ti o o f p o t a s s i u m p e r m a n g a n a t e t o p h o s p h o r i c a c i d r a n g e s b e t w e e n 1 : 0 .7 a n d

1 : 1 . 1 . T h e b l each ed f abr ic i s t h en s cav an g ed w i th an aq u eo u s s o lu ti o n o f an o r g an i c

r ed u c in g ag en t , s u ch a s s o d iu m b i s u lp h i t e , a t a p H b e lo w 4 . 0 . T h e f ab r i c i s t h en

s co u r ed w i th h o t w a t e r o r s team .

A co n t in u o u s o r s em i - co n t in u o u s p r o ce s s f o r b l each in g o f j u t e f ab r i c w i thch lo r in a t ed d e r iv a t i v es o f cy an u r i c ac id i s d ev e lo p ed [1 2 6] . T h e p r o ces s co m p r i s e s

a p re l im inary t r ea tment w i th bo i l ing water , fo l lowed b y im pregnat ion o f the mater ia ls

w i th 0 . 4 - 0 . 6% aq u eo u s a lk a l i n e s o lu t io n , an d t h en s u b j ec t i o n o f t h e m a te r i a l t o

s t eam t r ea tm en t . T h e r ea f t e r , t h e m a te r i a l is t r ea ted a t 2 0 -5 0~ w i th a m ix tu r e o f

t r i ch lo r o cy an u r i c ac id an d cy an u r i c a c id (w i th av a i lab l e ch lo r in e co n t en t 7 -1 5 g / l) ,

con ta in ing sod ium carbonate o r b icarbonate . The p H of the so lu t ion i s f ina l ly ad jus ted

to 4 - 5 w i th ace t i c ac id o r p h o s p h o r i c ac id . T h e t r ea t ed m a te r i a l i s t h en b l each ed

w i th H2 02 . T h e t im e o f t r ea tm en t i s u s u a l ly 4 0 - 60 m in , b u t can b e ex t en d ed t o 2 h

in th e ca s e o f a h eav y f ab ri c w i th h ig h l i g n in co n t en t .





20 2 B le a c h ing o f Te x t il e s

m uc h lowe r tha n tha t o f ju t e . The l ign in is d i ff i c u lt t o r e m ov e in the we t p r oc e ss ing

of f l a x , a nd inc om ple te r e m ova l i s r e spons ib le f o r ye l lowing o f the f ib r e a f t e rb leaching .

B le a c h ing o f li ne n c a n be c a r r i e d ou t by e i the r sod ium hy poc h lo r i t e o r sod ium

c h lo r it e . L ine n c a n be b l e a c he d w h i t e f r om the g r e y s t a te w i thou t a ny p r io r bo i l ing

t r e a tm e n t by us ing h ighe r c onc e n t r a t ion o f sod ium c h lo r i te ( 20 -30 g /1 a t 80 ~ a nd

pH 3 .5-4) , the impu r i t ie s in grey flax ac t iva te sodium chlor ite . How ever , b lea ching

b y c h l o ri n e c o n t a in i n g c o m p o u n d s g i v e s o r g a n o h e l o g e n c o m p o u n d s A O X . T h i s i s

c a use d by r e a c t ion wi th c h lo r ine c on ta in ing b le a c h ing a ge n t s w i th l i gn in [139 ] .

Th i s p r o b le m i s e l im ina te d by r e p la c ing i t w i th a no the r b l e a c h ing a ge n t tha t al so

l igni fy fu l ly .

A t e c hn ique f o r r e m ova l o f f l a x r us t ( M e la m psoz a l in i ) f r om f l a x f a b r i c s i s

e s t a b l i she d [140] by us ing b le a c h ing m ix tu r e (Na OC 1 - H20 2). The f a b ri c m a de

f rom ru s ted f lax ya m s is tr ea ted w i th an aqueous so lu t ion o f NaOC1 (2 .5 g /1 of

a c t ive c h lo r ine ) a t pH 9 a nd a m bie n t t e m pe r a tu r e . Th i s i s f o l lowe d by t r e a tm e n t

w i t h 3 0 % H202 (3.5 g/ l ) a t pH 9 and a t a tem pera tu re of 85-95~ For good whi te ,

op t i c a l b r igh te n ing a ge n t m a y be f ina l ly a pp l i ed . T he e xha us t ion o f the ox ida n t i ss low a nd the de g r e e o f wh i t e ne ss c a n be im p r ove d , i f t he m o de r a t e s c our ing i s

done b e f o r e b l e a c h ing [ 141 ] . The m a in d i sa dva n ta ge by us ing sod ium c h lo r it e o r

p e r o x i d e b l e a c h i n g o f l in e n i s t h a t o f p r e s en c e o f " s p r i t ' ( r em m n a n t s o f w o o d y

c or e o f f l a x s t e m ) . The d ye ing p r ope r t i e s o f sp r it m a y d i f fe r f r om those o f the l i nen

f ib r e . The o n ly e f f e c t ive wa y to r e m ove i t i s by t r e a tm e n t w i th hypoc h lo r i t e .

Pe r a c e t i c a c id /pe r ox ide c om bina t ions c a n r e p la c e hypoc h lo r i t e /pe r ox ide a nd

s im i l a r wh i t e ne ss c a n be ob ta ine d a s the c h lo r ine r ou te [142 ] . The r e su l t s a r e

sum m e r i se d in Ta b le 6 .7 . Pe r ox ide i t s e l f i s a good de l ign i f i c a t ion a ge n t , a nd in

T A B L E 6 .7

R e f l e c t a nc e Va lue o f B le a c he d L ine n

Sta te Ref lec tan ce (%)

Gr e y l ine n 20

Ash sc our e d 30

Pe r ox id e b l e a c he d 6 5

Perace t ic ac id process 77

H y p o / p e r o x i d e b l e a ch 6 7



B le a c h ing o f Te x t i l e s 20 3

fac t , be t te r than pe ra ce t ic ac id [143] . I t i s l ike ly tha t pe race t ic ac id w i l l be able to

replace these agen ts both as b leaching and d e l igni fica t ion agents . The wa te r insolublep r oduc t s o f pe r a c e t i c a c id on lign in is a lm o s t n i l. On c he m ic a l a na lys i s o f the wa te r

in so lub le p r o duc t a f t e r t r e a tm e n t f o r 1 h , the p r opor t ion o f f unc t iona l g r oups a r e

a l so r e duc e d b y d i f f e r e n t de g r e e s ( Ta b le 6 .8 ). The h igh c h lo r ine c on te n t i n l i gn in

t rea ted wi th hyp ochlor i te indica tes tha t in th is ch lorina t ion i s mo re v igo rous , wh ereas

wi th so dium chlor i te oxida t ion processes a re dom inant and the chlor ina t ion reac t ion

is a lmost absent .

T A B L E 6 .8

The E f f e c t o f Ox id i s ing Age n t in the Func t iona l Gr oups

o f L ign in Ex t r a c t e d f r om F la x [ 144]

Func t iona l

g r o u p

M e t h o x y l

H y d r o x y l

C a r b o x y l

A l d e h y d e

Pe r c e n ta ge o f f unc t iona l g r oups in

Or ig ina l

l ignin

4 .47

6.50

1.23

6 .50

L ign in t r e a t ed w i th

Hypoc h lo r i t e H202 P A A N a C 1 0 2

2.23

0.83

0.23

7.50

1.55

4.15

0 .34

4.30

2.91

3.76

1.03

5.80

1 .62

2.41

0.76

4.55

Elemental Analysis % % % % %

58.39

6 .40

51.03

7.45

C a r b o n

H y d r o g e n

C hlo r ine

51.23

7.48

39 .86

5.96

12.90

49 .27

7.68

0 .30

6 .1 6 B l e a c h i n g o f B l e n d e d F i b r e F a b r i c s

I n t r op ic a l c oun t r i e s l i ke I nd ia syn the t i c f ib r e s b l e nde d wi th c e l lu los i c f ib r e s

f a b r i c s a re ve r y pop u la r due to the i r e xc e ll e n t c om bina t ion o f a e s the t i c p r ope r t i e s

a nd e a sy c a r e p r ope r t ie s . T hus , b l e a c h ing o f b l e nde d f ib r e f a b r ic s be f o r e f u r the r

p r oc e ss ing i s a n im po r t a n t s t ep . M a ny o f the p r e pa r a to r y p r oc e sse s u se d f o r na tu r a l

a nd syn the t i c f ib re s ha ve l i tt l e o r no a pp l i c a t ion in p r e pa r a t ion o f b l e nde d f ib r e

fabircs.

6 . 1 6 . 1 B l e a c h i n g p o l y e s t e r / c o t t o n b l e n d s

Polyes te r f ibre in b lends wi th ce l lu los ic f ibres in the ra t ios of 65/35 and 50 /50

are co m m on cons t ruc t ion . W hen ce l lu lose por t ion i s r ayon, the b lends ra re ly requi re



204 Bleach ing o f Tex t i le s

b l each ing , b u t w hen co t ton i s p resen t b l each ing i s u sua ll y neces sa ry . B l each ing

t rea tmen t s o f such b lends a re no rm al ly r equ i red t o r emov e t he na tu ra l co lou rs o fcot ton , s igh t ing colours and i f the polyes ter por t ion i s turned ye l low at the t ime o f

hea t-set t ing operat ion. Chlorine bleaching, peroxide bleaching and c hlori te bleaching

are employed wide ly . I f t he po lyes t e r po r t i on requ i res b l each ing , t hen ch lo r i t e

b lea chin g i s used , as th i s b leac hing a gent b leaches bo th polye s ter and cel lu lose . I f

t he po lyes t e r po r t i on does no t need b l each ing , t hen a pe rox ide b l each ing i s m ore

conven ient . How ever , in case ofh ypo chlo r i te b leaching , i f ch lor ine rem ains in f ibre

deg radat ion can occur . Peracetic ac id b leach ing causes no undue deg radat ion o f the

fibre.

Ch lor ine b leac hing can be done a t 1-2~ b leac hing pow der so lu t ion for 2-3 h ,

w hich i s fo l lowed by dec hlor inat ing trea tment . S odium th iosulphate , ac id ic sodium

sulphate , a m m onia , H202 e tc . can be used as dech lor inat ing agents .

Alkal ine hy drogen peroxide b leaching i s the most preferred sys tem for polyes ter /

cot ton blends a nd bleaching ca n be ca rried out on various equipm ent using batchwise,

sem i-cont inuo us and cont inuous m ethod. Table 6 .9 shows condi t ions for b leaching

T A B L E 6 . 9

Bleac h ing o f Po lyes t e r / Co t ton a t HT/ HP Cond i t i on wi th H202

Chemica l Concen t ra t i on

H y d r o g e n p e r o x i d e ( 3 5 % )

S od ium s i li ca te (38~

S od ium hydrox ide ( so li d )

S od ium t r i po lyphospha t e

SurfactantTempera tu re

T i m e

30-40 ml/1

1 0 - 1 2 ml/1

2-4 g/1

some quan t i ty

some quan t i ty130-140~

60-120 sec

wi th hydrog en pe rox ide i n HT/ HP equ ipm en t by ba t chwi se sys tem. How ever , t he

use o f con t inuous open wid th b l each ing wi th sho r t r eac t i on t ime has l ed t o

cons ide rab l e and d ram at ic ad vances i n t he b l each ing o f po lyes t e r /co t t on b l ended

fabr ics. I t enables the com plete pre- t rea tm ent to be acco m pl i shed in 12 m in ins tead

of 24 h r equ i red fo r pad - ro l l sys t em. In th i s sys tem the des i zed fab r i c a f te r

imp regna t ion wi th a li quor con t a in ing H202 (above rec ipe) so lu ti on a t 35~ is



B le a c h in g o f Te x t i l e s 205

s te a m e d ( he a te d to 9 5 -9 6 ~ a nd s to r e d in the J - B ox f o r 7 5 m in . The f a b r i c is t he n

w a sh e d a t 6 5~ a nd d ri e d . B le n de d f a b r i c s c on ta in ing c o lou r e d th r e a ds c a n be

b le a c he d a t 8 0~ in s t e a d o f 9 5 - 9 6~ w i thou t da ng e r o f b l e e d ing .

T h e m o s t e f f e c ti v e m e t h o d o f b le a c h i n g p o l y e s t e r / c o tt o n i s s o d i u m c h l o ri te ,

w h i c h m a y b e f o l l o w e d b y p e r o x i d e b l e a c h i n g . C h l o r i t e b l e a c h e s t h e h u s k , b u t

d o e s n o t d e s t r o y t h e m c o m p l e t e l y . P o l y e s t e r/ c o t to n b l e n d s m a y b e b l e a c h e d w i t h

sod ium c h lo r i t e in long l iquor s a nd a l so by pa d - s t e a m p r oc e ss [Ta b le 6 .10 ] . The

T A B L E 6 . 1 0

R e c i p e f o r B l e a c h i n g P o l y e s t e r /C o t t o n B l e n d s w i t h N a C 1 02

C o n d i t i o n J ig W i n c h b e c k P a d - s t e a m

(Dry- in-wet)

L iqu or r a t io 7 :1 - 3 :1 50 :1 -20 :1 7 0 % p ic k - up

N aC1 02 (80% ), g/1 5-7 1-2 10-20

Stab il iser , (g/ l) 2-4 0 .5-1 -

So dium ni t ra te , (g / l) 2-3 1-2 10-15

F o r m i c a c i d to m a i n t a i n

pH to 3 .5 - 4 3 .5 - 4 5 .5 - 6

R e a c t ion t e m p . , (~ 8 0 - 9 0 8 0 - 90 8 5- 9 0

R eac t ion t ime , (h) 1-3 1 2-4

a m oun t o f va r ious c he m ic a l s r e qu i r e d f o r b l e a c h ing de pe n d on the li quor ra t io . The

f a b r ic a f t e r b l e a c h ing i s r in se d a s ho t a s poss ib l e a nd a n a n t i c h lo r ina t ion t r e a tm e n t

i s g ive n wi th sod ium b i su lph i te . I n a no the r m e thod , t he c lo th i s s t e e pe d in the li quor

a t pH 3 to 3 .5 , sque e z e d a t 10 0 % p ic k - up , pu t i n a r e a c t ion towe r m a de o f t i t a n ,

pa s se d th r ough a he a t ing duc t so tha t t he c lo th t e m pe r a tu r e i s r a i s e d to p r ope r

t e m p e r a tu r e , pu t i n a s t a y ing c ha m be r wh e r e the c lo th is s te a m e d a nd b le a c he d .

Pe r a c e t i c a c id c a n a l so be use d f o r b l e a c h ing po lye s t e r / c o t ton b le nde d f a b r i c s

wi th a so lu t ion c o n ta in ing 4 g /1 pe r a c e t i c a c id , 1 g /1 t e t r a sod iu m pyr o pho sph a te

( s tabi l i se r ) an d 1 g /1 w e t t ing agen t wi th a liquo r ra t io o f 5 : 1 . Pe rac e t ic ac id has a

pH o f a bou t 1 .5 a nd the b l e a c h ing b a th so lu t ion i s a d jus t e d to pH 5 .5 w i th the he lp

of d i lu te a lka l i. The m ate r ia l is en te red cold and m n for 10 min . T hen the tem pera ture

i s r a i s e d to 6 5 - 70 ~ in 15 m in a nd b le a c h ing i s c on t inue d a t th i s t e m p e r a tu r e t i ll theconcen t ra t ion ofpe race t ic ac id drops to 0 .09 g /1 . The fabric i s then wa shed thoroug hly



20 6 B l e a c h i n g o f T e x t i le s

wi th ho t a nd c o ld wa te r . The b le a c h ing c a n be pe r f o r m e d in the k i e r o r in the j i gge r .

A s i n g le s t a g e c o m b i n e d s c o u r i n g a n d b l e a c h in g o f p o l y e s t e r /c o t t o n b l e n d e df a b r ic c a n a l so be done f o r e c onom y. Th e r e a re va r ious a ppr oa c he s w h ic h inc lude :

a lka l i t r e a tm e n t w i th de te r ge n t a nd pe r ox ide ho t b l e a c h ; a lka l i t r e a tm e n t w i th

de te r ge n t a nd sod ium c h lo r i t e b l e a c h ; sod ium c h lo r i t e a nd pe r ox ide b l e a c h ; a nd

p e r o x i d e c o l d a n d p e r o x i d e h o t b l e a c h .

6 .16 .2 B l each ing o f po lyes t er /woo l b l ends

T h e w o o l p o r t i o n c o n t a i n e d i n th e b l e n d s h o w r e v e r si o n t o a c re a m y c o l o u r a n d

ye l low ing o f the f a b r ic . I n ge ne r al , b l e nds c on ta in ing w oo l a nd po lye s t e r f ib r e s c a n

b e b l e a c h e d w i t h h y d r o g e n p e o r x i d e e i th e r i n a ci d o r al k a li n e m e d i u m w i t h o u t r is k

o f d a m a g e .

I n a c id m e d ium , the f a b r i c i s t r e a t e d wi th a so lu t ion c on ta in ing 30 - 40 m l /1H20 2

(35% ) , 2 -4 g /1 organ ic s tab i l ise r , 0 .25 g /1 w e t t ing agen t and 0 .25 g /1 de te rg ent a t pH

5.5-6 (ace t ic ac id) for 40-60 min a t 80~ or 2-2 .5 h a t 65~ Th e t rea ted fabr ics a re

t h e n g i v e n w a r m a n d c o l d r in s e .

I n a lka l ine m e d ium , the ba th c o m pr i se s o f H20 2 ( 35%) , 30 - 40 m l /1 ; sod ium

pyr o pho sph a te , 2 - 4 g/1 ; a m m onia to m a in ta in the pH be twe e n 8 .5 - 9 .0 . The ba th i sse t a t 40 ~ a nd the goods a r e t r e a t e d f o r 2 - 4 h , a nd r in se d we l l in wa r m a nd c o ld

water .

As pe r ox ide - b le a c he d goods t e nd to show r e ve r s ion to a c r e a m y c o lou r , i t i s

usua l t o f o l low w i th a tr e a tm e n t in r e duc ing a ge n t to s t a b i li s e the b l e a c h in a ba th

con ta in in g 3-4 g/1 s tab i l i sed hy dro sulp hi te and 1 g /1 synthe t ic de te rgen t a t 50~ for

30 - 40 m in , r in se d a nd d r ie d .

Po ly e s t e r / s i lk b l e nds c a n be b l e a c h e d by a s im i l a r m a nn e r to tha t o f po lye s t e r /

w o o l b l e n d s .

6 .16 .3 B l each ing o f ny lon / ce llu lo se b l ends

B l e n d s o f n y l o n a n d c e l lu l o s ic f ib r e s m a y b e b l e a c h e d w i th e i th e r H 2 0 2 o r

N a C 1 0 2 , u s i n g b a t c h w i s e o r c o n ti n u o u s m e t h o d [ 1 4 5 , 1 4 6 ] .

H 2 0 2 d o e s n o t b l e a c h n y l o n a n d n o r m a l m e t h o d s o f b l e a c h i n g d e g r a d e n y l o n

a n d c a u s e y e l l o w i n g . B l e n d s c o n t a i n i n g 3 0 % o r le s s o f n y l o n m a y b e b l e a c h e d b y

the c on t inu ous H20 2 m e thod , a n d in suc h c a se s c o tton wi l l a bso r b the pe r ox ide

p r e f e r e n t i a l ly a nd so p r o te c t t he ny lon f r om da m a ge . The use o f p r o te c t ive a ge n t sw hic h p r e ve n t und ue d a m a ge to the ny lon po r i ton o f the b l e nd i s re po r t e d [ 147] .



B l e a c h i n g o f T e x t i le s 20 7

T h e g o o d s a r e e n t e r e d i n t o a b a t h c o n t a i n i n g 2 - 3 v o l u m e H202, 1 g/1 sodium

hy dro xid e f l ake , 0 .2 g /1 per ox ide s t ab i l i s e r , 0 .25 g /1 seq ues te r ing age nt and 0 .002to 0 .05 g/1 f ree radic a l supp resso r a t 40~ the t em per a tur e i s ra i se d to 85~ and

t he n t he t r e a t me n t c o n t i nue d fo r 1 h . The t r e a t e d go ods a r e the n c o o l e d a n d r i n s e d

t ho rough l y . W he n a ppropr i a t e , s e l e c t e d op t i c a l b r i gh t e ne r s ma y be i nc o rpora t e d i n

t h e p e r o x i d e b l e a c h b a t h .

H ypoc h l o r i t e doe s no t da ma ge ny l on bu t i t ha s go t no b l e a c h i ng a c t i on on i t .

S od i um c h l o r i t e c a us e s no de g ra d a t i on o f e i t he r c e l l u l os ic o r po l y a m i de a nd i s a

be t t e r b l e a c h i ng a ge n t t ha n pe ra c e t i c a c i d fo r c o t t on . Fo r ba t c hw i s e b l e a c h i ng t he

fabr ic i s t rea ted wi th a so lu t ion conta in ing sodium chlor i t e (2-5 g / l ) a t pH 3 to 4 a t

90~ for 1 ~/2 to 2 h . Th i s i s fo l low ed by a trea tm ent in a 2 g /1 so lu t ion of sod ium

c a rbo na t e a t 40 -50 ~ a nd f i na l ly ho t a nd c o l d r i n s e s a r e g i ve n i n w a t e r . Pa d - ro l l

a n d c o n t i n u o u s p r o c e s s e s a r e a ls o u s ed f o r b l e a c h i n g p o l y a m i d e / c e l l u l o s e m i x t u r e.

6 . 1 6. 4 B l e a c h i n g o f n y l o n /w o o l b l e n d s

I t i s d i f f i c u l t t o b l e a c h t h i s b l e nds s i nc e t he me t hod no rma l l y us e d fo r ny l on

d e g r a d e w o o l . T h e u s u a l m e t h o d is e it h e r to b l e a c h th e w o o l p o r t io n w i t h H202 at

l ow t e m pe ra t u r e [ 148] o r to c a r ry ou t r e duc t i on b l e a c h i ng p roc e s s [ 149 ]. A l ka l i neH202b l e a c h i ng a l w a ys da m a ge t he po l ya mi de f ib r e s t o some e x te n t . N orma l a l ka l ine

H202 b l e a c h i n g p r o c e s s m a y b e u s e d w i t h s a f e ty o n b le n d s c o n t a i n i n g u p t o 2 5 %

p o l y a m i d e , b u t a n a c id b l e a c h m u s t b e u s e d w h e n p r o p o r t i o n e x c e e d s t h is f i g u re .

The f a b r i c c a n be b l e a c he d w i t h a s o l u t i on c on t a i n i ng 12 -15 ml / 1 H202 (35~

2 g/1 t e t r a s od i um pyro pho s pha t e , 1 g /1 ED TA ( 30 % ) a n d 0 . 25 g /1 p ro t e c t i ve a ge n t

a t 6 0 -6 5~ fo r 45 -6 0 m i n a nd the n r i n s e d w e l l i n w a t e r .

6 .16 .5 B leach ing o f acry l i c / ce l lu los i c b l ends

I f t he c e l l u l os i c po r t i on i s c o t t on , b l e a c h i ng i s i nva r i a b l y r e qu i r e d fo r th i s f ib r e .

I f t he a c ry l ic po r t i on doe s no t r e qu i r e b l e a c h i ng , t he n a pe ro x i de t r e a t m e n t c a n be

done a t pH 9 . 5 . The a l ka l i ne c ond i t i on s hou l d no t be h i gh a s o t he rw i s e i t w ou l d

c a us e de g ra da t i on o f t he f ib r e . The f a b r i c i s t r e a t e d w i t h a so l u t i on c on t a i n i ng

7 .5-10 .0 g /1H202 (35%), 3 g/1 sod ium s i li ca te (79~ and 1 g /1 sod ium carbo na te

a t 9 0 ~ fo r 45 -6 0 mi n . A f t e r b l e a c h i ng t he ba t h is c oo l e d s l ow l y to 50 ~ r i n s e d

a nd n e u t r a l i s e d .

W he n a c ry l ic f i b r e a l so r e qu i r e s b l e a c h i ng , t he n mi l d c h l o r i te t r e a t m e n t w i ll a c ton bo th the f ibres in the b lend . The ba th i s pre par ed a t 35~ w i th 1 .5 g/1 sod ium



2 08 B l e a c h i n g o f T e x t i le s

ch lor i te , 2 g /1 oxal ic ac id , 1 g /1 te t r aso d ium pho spha te and 1 g /1 cor ros io n inh ib i to r.

T h e b l each b a th s h o u ld g iv e a p H o f ab o u t 3 .5 t o 4 . 0. T h e t em p er a tu r e o f t h e b a thi s r a i s ed t o 90~ o v e r 3 0 m in an d p r o ces s in g c o n t in u ed f o r 3 0 -4 5 r a in a t t h is

t em p er a tu r e . T h e b a th is co o l ed s lo w ly to 50~ an d t h en r i n s ed th o r o u g h ly . An

an t i ch lo r t r ea tm en t i s g iv en i n a b a th co n t a in in g s o d iu m b i s u lp h i t e (1 . 5 g / l ) an d

t e t r a s o d iu m p h o s p h a t e (1 .5 g / l) a t 60~ f o r 2 0 - 3 0 m in , co o l ed th e b a th an d r i n s ed

w e l l . T h e t e m p e r a t u r e o f d r y i n g s h o u l d n o t e x c e e d 8 0 ~

6 . 1 6 . 6 B l e a c h i n g o f a c r y l i c / w o o l b l e n d s

H y d r o g en p e r o x id e i s n o t s u i t ab l e f o r ac r y l ic f i b r e a t h ig h ly a lk a l i n e c o n d i t i o n

an d m o r eo v e r ac r y l i c f i b r e t u r n s y e l l o w i s h o n a lk a l i n e p e r o x id e t r ea tm en t . T h e

d i s co lo u r a t i o n can b e im p r o v e d b y a f te r - t r ea tm en t w i th f o r m ic ac id i n p r e s en c e o f

d e t e r g en t . Acr y l i c / w o o l b l en d s can a l s o b e b l each ed b y a r ed u c t io n b l each o r b y

c o m b i n a t i o n o f p e r o x i d e a n d re d u c t i o n b l e a c h i n g p r o c e s s .

6 . 1 6 . 7 B l e a c h i n g o f a c e t a t e / c e l l u l o s i c b l e n d s

Diace t a t e / v i s co s e b l en d s h av e b een u s ed i n d r e s s w ea r , s h i r t in g an d u n d e r - w e a r .

T h e s e b l e n d s m a y b e b l e a c h e d w i t h h y d r o g e n p e r o x i d e o r s o d i u m h y p o c h l o r i t e ,

p re ferab ly the la tte r .T h e g o o d s m ay b e t r ea t ed w i th a s o lu t io n co n t a in in g 5 g/1 H2 02 (1 00 v o l . ),

2 g/1 sod ium s i l ica te an d 1 g /1 soap a t 70-75~ fo r a m in im um t ime of 30 r a in .

B l e a c h i n g c a n b e d o n e b y t r e a t m e n t w i t h a s o l u t i o n c o n t a i n i n g s o d i u m

hyp och lor i te (2 -3 g /1 ava i lab le ch lor ine) ad jus ted to pH 10 a t room tem pera tu re fo r

3 0 m in , an d t h en t h e f ab r ic i s g iv en co ld t r ea tm en t w i th 1 m l / 1 HC1 an d t h o r o u g h

r ins ing . A l te rna t ive ly , an ac id so lu t ion i s p repa red w i th 10 ml /1 sod ium hypo chlor i te

(5 0~ an d 2 m l /1 h y d r o c h lo r i c ac id ad ju s t ed t o p H 3 . T h e t r ea tm en t is ca r r i ed o u t

co ld f o r 4 0 m in , g o o d s a r e w e l l r i n s ed an d t h en t r ea t ed i n a s eco n d b a th w i th 3 g/1

s o d iu m b i s u lp h i t e a t 4 0~ f o r 2 0 r a in .

6 . 1 6 .8 B l e a c h i n g o f p o l y e s t e r / l in e n b l e n d s

P o ly e s t e r / l o n g - s t ap l e f i b re s a r e u s ed i n t h e l i n en in d u s t r y , w h e r e y am s m ay b e

o f e i th e r t he " s t r e t c h b r o k e n " o r " u n b r o k e n " t yp e , b u t m o r e c o m m o n l y o f t he

l a tt e r. T h e l in e n c o m p o n e n t o f th e b l e n d m a y b e o f b l e a c h e d o r u n b l e a c h e d f ib r e

an d y am s s p u n f r o m u n b leach ed f ib r e m ay b e b l each ed b e f o re w eav in g . Mo s t f ab ri c s

in th i s b lend are woven on s ized (s ing les ) warps . Un m odif ied w arp s izes a re rem ove db y en zy m e t r ea tm en t an d n o n - ce l l u lo s i c m a t t e r i s r em o v ed b y an a lk a l i n e s co u r .



B l e a c h i n g o f T e x t il e s 2 09

Go o d s m ad e f r o m b l each ed y a r n s o r f i b r e s r eq u i r e o n ly a l i g h t s co u r w i th 2 g / 1

s o d a - a s h a lo n g w i th 1 g/1 d e t e r g en t . Go o d s p r ep a r ed f r o m u n b le ach ed y a r n s o r

f i b re a r e p ad d ed w i th d il u t e cau s ti c s o d a s o lu t io n a t 70 t o 80~ b a t ch ed o n a r o l l

and a l low ed to ro ta te a t th i s tem pera tu re fo r 24 h . The g ood s are then r insed , sco ured

an d b l each ed w i th h y d r o g en p e r o x id e o r w i th s o d iu m h y p o ch lo r i t e . So d iu m ch lo ri te

i s n o t n o r m a l ly u s ed f o r b l eac h in g t h i s b l en d .

6 . 1 6 .9 B l e a e l l in g o f w o o l / v i s c o s e b l e n d s

B l e a c h i n g i s u s u a l l y c a r r i e d o u t b y i m m e r s i o n o f t h e m a t e r i a l i n a l i q u o r

co n ta in in g 1 -2 v o l. H2 02 an d 5 g/1 s o d iu m s i li ca te o r s o d iu m p y r o p h o s p h a t e a t

30~ ov ern ig h t o r a t 40-50~ fo r 4 h . The ba th i s ad jus ted to pH 8 and i t i s adv isa b le

to ad d 0 . 2 5 - 0 . 5 g/1 o f a s u i tab l e s eq u e s t e r i n g ag en t . F o r t r ea tm en t b y t h e s h o r t e r

t im e , t h e co n cen t r a t i o n of HzO 2 may b e i n c r eas ed t o 3 t o 3 . 5 v o l s . T h e am o u n t o f

H2 02 , h o w ev e r , d ep en d s o n t h e q u a l i t y o f w o o l o r p r o p o r t i o n o f v i s co s e i n t h e

b lends .

6 . 1 6 .1 0 B l e a c h i n g o f v i s c o s e / c o t t o n b l e n d s

V i s c o s e / c o t t o n b l e n d s c a n b e b l e a c h e d e i th e r b y b a t c h m e t h o d o n j i g a n d w i n c h

o r b y a co n t in u o u s p r o ces s u s in g J - Bo x [1 5 0 ] . B l each in g i s d o n e o n a w in ch w i ths o d iu m h y p o ch lo r i t e (2 g / 1 av a i l ab l e ch lo r in e ) ad ju s t ed t o p H 1 0 - 1 1 w i th s o d iu m

carbo nate , fo r 1 h a t 25~ or a l te rna t ive ly , w i th 5 g /1 sod ium ch lor i te ad jus ted to

p H 4 w i th ace t ic ac id f o r 3 0 m in a t 80~ Al t e r n a t i v e ly , th e b l eac h in g t r ea tm en t

m a y f o l l o w w i t h a lk a l in e h y d r o g e n p e r o x i d e a t 8 5 ~

In t h e co n t in u o u s m e th o d th e f ab r i c is s a tu ra t ed w i th b l each l i q u o r co n s i s t i n g o f

H2 02 an d p o t a s s iu m p e r s u lp h a t e , p a s s ed t h r o u g h a J - Bo x , f o l l o w ed b y s h o r t b o i l -

o f f , r i n s in g an d d r y in g o v e r can s w i th a t o t a l p r o ces s in g t im e o f 1 5 m in . T h e

t em p er a tu r e i n t h e J - Bo x ap p r o x im a te s 70~ an d t h a t o f w as h l iq u o r 80~

6 . 1 7 B l e a c h i n g o f C o t t o n W e f t K n i t te d . F a b r i c s

Kn i t t ed f ab r i c s can b e p r o d u ced f r o m a w id e r an g e o f f i b re s an d b l en d s , e i t h e r

a s fl a t f ab r i c o r g a r m en t s . Ga r m e n t s , r an g in g f r o m o u te r w ea r ( i n c lu d in g s p o r t an d

l e i s u r e w ea r ) t o h o s i e r y , a r e g en e r a l l y w ef t k n i t t ed . War p k n i t s u s u a l l y r eq u i r e

f i la m e n t y a m s w h i c h a r e 1 0 0% s y n t h e ti c a n d d o n o t n o r m a l l y r e q u i re b l e a c h i n g .

T h e w ef t k n i t t ed f ab r ic s p r o d u ce d f r o m 1 00% co t to n an d s y n th e t i c f i b r e /co t t o n

b l en d s m ay b e ca l l ed j e r s ey , r i b o r f l eece d ep en d in g o n h o w th e l o o p l i e . Wh i l ew ef t k n i t t ed f ab r ic s a r e co m f o r t ab l e t o w ea r , s i n ce t h ey a r e l ig h t an d p l eas in g t o th e




sk in , t he y do ha ve d i sa dva n ta ge s in tha t t he y a r e e a s i ly de f o r m e d by m e c ha n ic a l

s t r e s se s a nd we t c r e a se d tha n w ove n f a b r i c s.S i n c e k n i t ti n g y a r n s a r e u n s i ze d a n d u s u a l ly c o m b e d t o r e d u c e s e e d a n d ' tr a s h

c on te n t ' , t he r e i s no r m a l ly a ny ne e d f o r t re a tm e n t p r io r t o b l e a c h ing . T he kn i t t i ng

lub r i c a n t s wh ic h r e p la c e the s i z e on wove n f a b r i c s a r e u sua l ly s e l f s c our ing , bu t

s o m e t i m e s f r o m t h e ir v e r y v o l u m e m a y c r e a te p r o b l e m s w i t h f o am a n d s t ai n s in

w e t p r o c e s s i n g o r in t h e k n it ti n g m a c h i n e w h i c h n e e d t o b e t re a t ed w i th s o l v e n t

c on ta in ing a ux i l ia r i es .

The b le a c h in g o f kn i t t e d f a b r i c s -l ike tha t o f w ove n f a b r i c s -shou ld r e su l t i n h igh

w h i t e n e s s , l o w c h e m i c a l o r a b r a s i o n d a m a g e , l o w c r e a s e f o r m a t i o n a n d h i g h

a bso r ba nc y to wa te r. S od ium h ypoc h lo r i t e is ge ne r a l ly no t su i ta b le f o r b l e a c h ing o f

kn i t t e d f a b r i c s on a c c oun t o f a lka l ine na tu r e o f the b l e a c h p r oc e ss a nd r e c e n t

r e s t ri c t io n o n a d s o r b a b l e o r g a n o - h e l o g e n c o m p o u n d ( A O X ) g e n e r a t io n . H o w e v e r ,

hyp oc h lo r i t e m a y be use d a t pH 11 a nd at t e m p e r a tu r e no t e xc e e d ing 30 - 35~ in

p r e se nc e o f e f f e c t ive we t t ing a ge n t [151 ] . Th e n the f a b r i c i s g ive n a n a n t i c h lo r

t r e a tm e n t , t he who le p r oc e ss t a k ing 3 - 4 h.

Th e a c id i c na tu r e o f sod ium c h lo r i te b l e a c h ing p r oc e ss m a k e i t i de a l fo r kn i tt e df a b r i cs , a s the na tu r a l f a ts a nd wa xe s o f the f ib re w e r e no t s c our e d ou t , e nha n c ing

the so ft , vo lu m ino us ha nd le o f the goods . A l t e r na t ive ly , a s ing le - s t a ge c om bine d

s c o u r i n g a n d b l e a c h i n g c a n b e o p e r a t ed u s i n g a p e r o x i d e s o l u t io n c o n t a i n i n g m i ld

a lka l i, a de t e r ge n t a n d so d ium s i li c a te a s s t a b i l is e r . The a lka l in i ty o f pe r ox ide

b le a c h ing c o nd i t ions m a y sc o ur ou t t he na tu r a l f a ts a nd wa xe s f r om k n i t t e d f a b r ic s

a nd r e su l t s i n ha r she r ha nd le a nd po or e r s e w a b i l it y . A so f t f a b r ic c a n be p r oduc e d

b y t r e a ti n g w i th s o f te n e r a f te r p e ro x i d e b l e a c h i n g . T h e c o m b i n e d h y p o / p e r o x i d e

p r oc e ss g e ne r a l ly p r ov ide s the h ighe s t w h i t e ne ss on kn i t t e d c o tton f a b r ic s . C o t ton

h o s i e r y m a d e f r o m d a r k c o l o u r e d m e r c e r i z e d y a m c a n b e r a p i d l y b l e a c h e d b y

h y p o c h l o r i t e f o l l o w e d b y p e r o x i d e w i t h o u t p r e l im i n a r y s c ou r. C o t t o n i n k n i t te d

f a b r i c s is u sua l ly l e s s s e e dy tha n f o r w ove n f a b r ic s m a k ing on e s t e p sc our /b l e a c h

w i t h p e r o x i d e m o r e r e a d i l y a p p l i c a b l e . L o w t e n s i o n m a c h i n e r i e s a r e g e n e r a l l y

suitable .



Bleach in g o f Tex t i l es 211

R E F E R E N C E S

1 T en na nt , Br i t . Pa t ., 2391 (1799).

2 J . E . Ne t t les , Am er . Dye stu f f Rep . , (1968) 31 .

3 D. A. Clibbe ns an d B. P. Rid ge, J . Tex ti le Inst . , 18 (1927) T135 .

4 Du Pon t, Un ited S tates Pat . , 2 , 304, 474.

5 R. L. De rry, J. Soc. Dy ers Co lourists , 71 (1955 ) 884.

6 G. M. Na bar , V. A. Shena i and J. G. N air , Ind. J. Tec h. , 4 (1966) 124.

7 Amer ican Cot ton Handbook , 1941 , p 659 .

8 H. S. B ri t ton and E. N. Dodd s, T. F. S. , 29 (1933) 537.

9 Texti le Mfr . , 87 (1961) 109.

10 H. B orsten, Tex ti le R eco rder , 82, No . 974 (1964) 71.

11 A.A . Bu r insk i i and I. N. Ki taeva , Resu rsosbergayush ch . Technol . p ro tsessy v

keks t i l , pr-ve, L. (1988) 9, 12B, 10 (Oct 1989) ( in R ussian ) .

12 V .R . Ly uts, V. F. Seldatenko va and I. Ya. Kalontarov, R eferat Zhur , 12B (Aug

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15 R .N . S teev e, Th e Ch em ica l P r o cess In d u s t ri e s , Seco n d Ed n ., McG r aw Hi l l

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16 P. N ey, Tex ti l Praxis, 29 (1974) 1392, 1552.

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64 Pales t ine Po tash Ltd. , BP 596, 192 ; 596, 193.

65 Ec us ta Paper Corpn . , US P, 2 , 477, 631.

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67 S o lw ay C ie , Be lg i an P 36 5 , 07 2 ; 365 , 084 .

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69 ICI Ltd . , Tec hnical Inform at ion , p 960.

70 Blume, Text i lveredlung, 4 (1969) 88.

71 S. He nrik son , Ind. Pulp. Pap. , 22 (1967) 22.

72 M ey be ck and Ivann ow , Bul l . Ins t. Text . France, 39 (1953) 23 .

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77 B. I. Lam abo rn , USP 2 , 810, 717.

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144 R. R . M ukh er jee and T. Rad hakr i shn an, Text i le Prog. , 4(4) (1972) 56.

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147 To urd ot , Te intex, 37 (Feb 1972) 67.

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149 Schm idt , In tem at . Text . Bul l . No. 4 (1972) 371.

150 B. K. Eas ton , Amer . Dy es tu ffR ep . , 51 (14) (1962) 502.

151 P. Gr5"nig, Deu tsch. Faer ber -Ka lend er, 80 (1976) 48.



Chapter 7

B L E A C H I N G A N D W A S H I N G E Q U I P M E N T

7 . 1 I n t r o d u c t i o nT ex t i l e s can b e b l each ed an d w as h ed i n l o o s e f o r m , y a r n f o r m an d f ab r i c (w o -

v en an d k n i t t ed ) f o r m . L o o s e s to ck can b e b l each ed b y s t eep in g m e th o d in a s u it -

ab l e v es s e l . Yar n s an d t o p s a r e b l each ed u s in g s k i en s o r p ack ag e m ach in es . Kn i t

g o o d s a r e co m m o n ly s co u r ed an d b l each ed i n co m p ar a t i v e ly s m a l l b a t ch es i n w in c h

an d j e t m ach in es [ 1 , 2 ] . Ho w ev er , co n t in u o u s b l each in g r an g es f o r co t t o n k n i t g o o d s

a r e av a il ab le . R o ta r y m ach in es can b e u s ed f o r b l each in g o f h o s i e r y f ab r ic s . W o v e n

f ab r ic s can b e b l each ed i n t h r ee d i f fe r en t w ay s , s u ch a s b a t ch p r o c es s (k i e rs ) , s em i -

co n t in u o u s p r o ces s an d co n t in u o u s p r o ces s . In t h e s em i - co n t in u o u s p r o ces s , p ad -

b a t c h a n d p a d - r o l l s y s t e m s a n d i n c o n ti n u o u s p r o c e s s , ro p e o r o p e n - w i d t h J - B o x e s

a r e p o p u l a r . O v e r t h e p a s t fe w y e a r s , th e r e h a v e b e e n n e w o p e n - w i d t h c o n t i n u o u s

m a c h i n e r i e s d e s i g n e d , d e v e l o p e d a n d i n s t a l l e d i n t h e m o d e r n b l e a c h h o u s e a n d

h av e m ad e e f f i c i en t im p r es s io n i n t h e i n d u s t r y . "

7 .2 B a t c h B l e a c h i n g P r o c e s s M a c h i n e r i e s

I n th e e a r l i e r d a y s b l e a c h i n g o f w o v e n p i e c e g o o d s w a s u s u a l l y c a r r i e d o u t b y

p i l i n g t h e m a te r i a l i n to g l azed b r i ck o r ti le l i n ed t an k s co n t a in in g h y p o ch lo r i t e s o -lu t io n s . T h e u s u a l p r ac t i ce i s t o tu r n t h e l o ad i n to an ad j acen t s eco n d t an k , s o th a t

t h e en d w h ich en t e r ed f i rs t is a l so d r aw n o u t f i rs t. T h e b in o r p i t s h av e f a l se b o t to m

w h ich a l l o w s d r a in a g e o f b l each in g s o lu ti o n . T h e c lo th is a l l o w e d to d w e l l t h e r e

u n t il t h e b l each in g i s co m p le t e .

B le ach in g o f co t t o n , li n en , r ay o n , m an - m ad e f i b re s e tc . in t h e f o r m o f w o v en o r

k n i t t ed f ab r ic s , h an k ed y a r n s an d l o o s e s t o ck w i th ap p r o p r ia t e b l each in g ag en t s can

b e ca r r i ed o u t i n p ac k b l each in g r an g es (F ig . 7 - 1 ) o r in k i e r s . T h e b l ea ch in g t an k s

c a n b e f u l ly e n c l o s e d o r o p e n ty p e e q u i p p e d w i t h a u t o m a t i c t e m p e r a t u r e c o n t r o l

a n d t he e n t i re p r o c e s s c a n b e p r o g r a m m e d c o n tr o l. T h e c a p a c i t y o f t h e m a c h i n e

m ay b e 2 00 - 2 000 k g g o o d s . T h e r e i s an a r r an g e m en t o f au to m a t i c p l a i t e r t o p i le t h e

f ab r i c r o p es (F ig . 7 - 2 ) . T h i s en s u r e s ev en tw i s t l e s s p i l i n g o f f ab r i c r o p es a t a l l

speeds , r egard le ss o f f abric weigh t . Rai l i s m oun ted to serve severa l t anks sepera te ly .

Af t e r t h e b l each in g s o lu t i o n i s ad d ed s u f f i c i en t w a t e r i s ad d ed t o en s u r e t h a t t h e

l o a d i s c o m p l e t e l y i m m e r s e d . T h e t e m p e r a t u r e i s r a i s e d to t h e re q u i r e d t e m p e r a -



218 Bleach ing and W ash ing Equ ipmen t

F i g u r e 7 - 1 . P a c k b l e a c h i n g r a n g e s(Cou r tesy of Fr iedr ichsfe ld , Germ any) . Figure 7-2 . Automat ic rope p i ler forcircular tanks.

ture , the b leac h l iquor i s sprayed f rom the top and the l iquor percola tes through the

batch cont inuo us ly . In the l iquor c i rcula t ing sys tem only 2 h may be necessa ry , but

longer t ime i s requi red for open k ier type o f machiner ies . Af ter b leaching , the goods

m ay be wa shed i n t he s ame m ach ine i ts e lf , p re fe rab ly wi th warm wate r , t hen pu t

th rough a rope w asher .

Raw s tocks and yams in packages o r i n beams can be b l eached on ly by t he

l iquor c i r cu la t ing mach ines . Co t ton ya rn i n the fo rm o f hank can be b l eached as a

rope o f c lo th us ing p res su re k i e r s , wash ing m ach ines and hypoch lo r i te b l each ing

p i t s . Bu t t he modem t endency i s t o b l each i n a more e f f i c i en t manner i n dye ing

m ach ines in the form of beam s (Fig . 7-3) and pack ages (Fig . 7-4) . This mac hine

F igure 7 -3 . Un iver sa l HT dye ing and

b l e a c h i n g m a c h i n e ( C o u r t e s y o f

Arge l ich , Tea m es & C .A. , Spa~n).

F i g u r e 7 - 4 . R a p i d l o w l i q u o r r a t i opackage dye ing and b leach ing m ach ine

[3].



B l e a c h in g a n d W a s h i n g E q u i p m e n t 2 1 9

(Fig . 7 -3) i s su i t ab le fo r dye ing an d b leach ing of loose s tock and yarn as we l l as o f

w arp b e am s , t o p s an d ca rd ed s li v e r. A l l k n o w n n a t u ra l an d s y n t h e t ic f i b r e s can b et rea ted . The c y l indr ica l , ver t i ca l au toc lave i s l i f ted wi th a cen t ra l , con ica l supp or t

fo r the m ater ia l car r i e r , as wel l as wi th a d ra in va lve . The cover i s l i ft ed wi th a rap id

l o ck. C o u n t e rw e i g h t s p r in g s a s s i s t e a s y o p en i n g an d c l o s i n g o f th e l id . T h e m a i n

l in e o f d ev e l o p m en t i n p ack ag e d y e i n g m ach i n es (F ig . 7 -4 ) h as b een t h e ab i l i t y t o

d y e an d b l each a t h i g h t emp era t u re an d p re s s u re w i t h g rea t ly i mp ro v ed l iq u o r f lo w .

T h e a l k a li s co u r an d h y p o ch l o r i t e p ro ces s i s n o t p a r t i cu l a r ly s u i t ab le fo r y a m i n

s u ch fo rms . A s i n g le s tag e p e ro x i d e b l each i n g an d fo r fu ll w h i t e d o u b l e p e ro x i d e

b l each m ay b e r eq u i red .

In th e p as t i t h a s b een an d s t il l i s co m m o n p rac t i ce t o u s e m a i n l y w i n ch es o r j e t

m ach i n es fo r p r ep a ra t o ry o f b o t h w o v e n an d k n i t t ed f ab r i c s in t u b u l a r fo rm. S t a rt -

ing wi th the winch beck , mac hiner ies fo r p re- t rea tme nt p rocesses have pa ssed th rough

s ev e ra l s t ag es o f d ev e l o p m en t ( j ig , b eam, je t , o v e r f l o w ) , s o m e p a ra l l e l ed i n w as h -

i n g ma ch i n es . T h e cu r r en t tr en d s t o w ard s s m a l l e r s e r ie s h av e l ed t o a co m eb ac k o f

the conven t iona l sys tem s us ing j igge r m ach ines (F ig . 7 -5) fo r t ex t i le p rocess ing .

F i g u re 7 -5. A u t o m a t i c j i g g e r o f f e r in g ma x i m u m au t o m a t i o n an d en h an ced q u a l i ty

(Co u r t e s y o fM ezze ra -K l e i n ew efe r s S .p .A . , I t a l y ) .

N o w -a -d ay s , o l d o b s o l e t e h y d rau l i c j i g g e r s a r e r ep l aced b y n ew m o d e l s cap ab l e o f

w o rk i n g w i t h co n s t an t fab r ic t en s i o n an d ad j u s tm en t r an g i n g f ro m 1 an d 5 00 N w /

m w i t h a m ax i m u m w o rk i n g s p eed u p t o 1 5 0 m /mi n . W h ere b a t ch ed s i ze is a ro u n d

6000 m, j u m b o j i g g e r s an d p re s s u r i s ed j u m b o j i g g e r s [ F ig . 7 -6(b )] can b e u s ed fo r

b leach ing in open -wid th fo rm. In non-pre ssur i sed jum bo j iggers [F ig . 7 -6(a) ] p repa-





B l e a c h in g a n d W a s h i n g E q u i p m e n t 221

F i g u r e 7 - 8. N o v e l c o u n t e r fl o w r o p e t r e a tm e n t m a c h i n e

(Co u r t e s y o f MCS, S . p . A . , I t a ly ) .

i n a s p r ia l f a s h io n . T h e n e w r an g es a r e p r im a r i l y i n t en d ed f o r p r ew as h in g , b l each -

in g an d a f t e r w as h in g o f k n i t t ed an d w o v en f ab r ic s i n r o p e f o r m . T h ey can co m p r i s e

6 o r 1 2 w as h in g s ec t i o n s co n n ec t ed i n s e r ie s , a g u id e ro l l e r, a ro t a r y p u l s a to r f it ted

w i th s ev e r a l i n d iv id u a l m i l l i n g r o ll e r s , a h ea t r eco v e r y u n i t an d a f ab ri c f eed an d

d e l iv e r y s y s t em in a s t a in le s s s t ee l h o u s in g . T h e w as h in g s ec t i o n s each h av e anin l e t an d o u t l e t an d a r e i n t e r co n n ec t ed b y a f l ex ib le t u b e r o u n d th e r o t a r y p u l s a to r .

T h e f ab r ic i s d r aw n in to t h e m ach in e b y m e an s o f a t r an s p o r t r o l le r an d f ed t o th e

in d iv id u a l w as h in g s ec t i o n s . T h e l a t t e r a r e co n n ec t ed s o t h a t f r e s h w a te r can b e

s u p p l i ed t o t h e en t i r e m ach in e o n a co u n te r f l o w p r in c ip l e . T h e r e i s p r o v i s io n o f

m e t e r i n g t h e c h e m i c a l s a n d t h e n e c e s s a r y t e x ti le c h e m i c a l s c a n b e a d d e d i n co n -

t r o l led q u an t i t ie s a n d t h e co r r ec t p r o ce s s in g t em p er a tu r e can b e m a in t a in ed f o r t h e

in d iv id u a l w as h in g s ec ti o n s . T h e p r o ces s co n t ro l t ech n o lo g y s to re s a ll m ach in e an d

p r o ces s cy c l e d a t a an d m a k es o v e r r i d in g o p e r a t in g d a t a l o g g in g u n i ts acces s ib l e v i a

p r o f ib u s .

An o th e r o n e i s sp i r a l j e t b l each in g u n i t in w h ich t h e w o v en an d k n i t t ed f ab r i c s

can b e p r e - t r ea t ed a s s h o w n in F ig . 7 - 9 . In th i s m ach in e , t h e f ab r i c i s m o v ed in a

sp i r a l , in rope fo rm, th rough the tube , us ing je t s tha t l i f t ed the f abr ic ou t o f one

co m p ar tm en t an d d ep o s i t ed i n t h e n ex t [7 - 9 ] .

A co m p ar i s o n o f t y p i ca l b l each in g r ec ip es o f co t t o n f ab ri c f o r b a t ch b l eac h in g

i n d i f fe r e n t e q u i p m e n t w i t h h y d r o g e n p e r o x i d e i s su m m e r i s e d i n T a b l e 7 .1 . W h e nm ak in g - u p a b l eac h in g b a th , n a tu r a l l y t h e q u a l i t y o f co t t o n , d eg r ee o f p r e - t r ea t -

m en t , l i q u o r ra t i o , eq u ip m en t u s e d an d t em p e r a tu r e m u s t a ll b e t ak en i n to acco u n t .



222 B l e a c h in g a n d W a s h i n g E q u i p m e n t

1. Jet

2. Channel

3 . Hea t exchang er

4 . By-pass5 . Ci rcula t ion pum p

6. Side tank

7. Con t ro l panel

8 . Load ing winch

9. Rolls

10. Doors

11. Un loading w inch

12. Drive

F igure 7 -9 . S p i ral j e t b l each ing un i t (Cour t esy o f K~ s t e r K BR ) .

7 . 3 S e m i - C o n t i n u o u s B l e a c h i n g P r o c e s s M a c h i n e r i e s

Both pe rox ide and sod ium ch lo r i t e can be used fo r b l each ing o f co t t on and

po lyes t e r / co t t on goo ds by s em i -con t inuous open-w id th fo rm. In the pad -ba t ch (o r

pad-s t ack ) p roces s t he padded goods a re ba t ched and t hen covered wi th p l as t i c

shee t t o p reven t evap ora t ion o f b leach ing agen t o r gas and t hen a l l owed to li e fo r

24 h . In the pad-ro l l process (Fig . 7-10) , the goods af ter padding wi th b leaching

so lu ti on a re t hen hea t ed i n a s t eam ches t and ro l led -up i n a mo b i l e ba t ch cham berfor 4-12 h . The c ham ber can be sealed so that no gas can evolve dur ing b leaching .





2 2 4 B l e a c h i n g a n d W a s h i n g E q u i p m e n t

ch lor i te so lu t ions a re su itab le . How ever , fo r a longe r b leach ing t ime, a smal l amo unt

o f s o d a - a s h i s u s e f u l t o m a in t a in t h e s t ab i l it y o f t h e b a th . T h e r o ll i s r o t a t ed g en t lyd u r in g i t s d w e l l p e rio d . T h e p r o ced u r e i s f o l l o w ed b y a h o t w as h w i th 1 % s o d a - as h

in t h e ca s e o f H2 02 an d an t i ch lo r t r ea tm e n t w i th b is u lp h i t e i n t h e ca s e o f s o d iu m

ch lo r i t e an d th en s o ap in g t h e g o o d s in a b a th a t ab o u t 80~ T h e p ad - j i g p r o ces s is

a l s o u s ed f o r t h e b l each in g o f tex t il e s . T h es e s y s t em s a r e s im p le t o o p e r a te b u t h av e

s o m e d i s ad v an tag e s l i k e im p a i r m e n t o f t h e l ev e ln es s o f p r e - t r ea tm en t d u e to v a r i a -

t io n i n d w e l l t im e an d t em p er a tu r e f r o m b a t ch t o b a t ch . Ho w ev er , m ach in e r i e s w i th

e a s y a n d a u t o m a t i c b a t c h i n g a n d u n b a t c h i n g s y s te m s a re d e v e l o p e d w i t h s p e c ia l

f ea tu r e s f o r t h e v a r io u s p r e - t r ea tm e n t an d b l each in g p l an t .

7 .4 C o n t i n u o u s B l ea c h i n g b y J - B o x S y s t em s

T h e m a in p u r p o s e o f t h e co n t in u o u s b l each in g s y s t em , w h e th e r i n t h e r o p e f o r m

o r in o p e n - w id th f o r m , i s t o r ed u ce t h e tim e o f b l each in g an d t h e co s t o f l ab o u r

in v o lv ed . Co n t in u o u s b l each in g i n J - Bo x in r o p e f o r m w as s t a r t ed i n t h e l a t e i n

1 93 0s w i th t h e i n tr o d u c t io n o f h y d r o g e n p e r o x id e [1 0, 1 1] an d p l an t s ca le eq u ip -

m en t h a d b ee n b u i l t an d a s u i tab l e p r o ced u r e w as d ev e lo p ed [ 1 2 ] . In 1 94 2, t h e u n i t

u s ed i n t h e b l each r an g e w as ca l l ed a J - P il e r [ 1 3 ] , b u t b y 1 95 2 th e n am e h ad b e -co m e J - Bo x an d b l eac h e r ' s d r eam o f o n e - s t ep p r o ces s h a d f i n a l ly co m e t r u e [ 1 4 ].

T h e h ea r t o f t h e p r o ces s i s t h e J - Bo x s to r ag e u n i t an d t he s h ap e i s li k e t h e E n -

g l i s h l e t te r ' J ' . I n r o p e b l each in g t h e f ab r ic i s p u l l ed t o g e th e r t o fo r m a s o m e w h a t

c i r cu l a r m as s , w h ich i s lo o s e en o u g h f o r p en e t r a t i o n an d r e s em b les a l a r g e r o p e ; i n

ope n-w id th fo rm the f abr ic i s unde r tens ion and i s f la t and sm ooth . J -Boxes , w hethe r

o p en (Bec co t y p e ) o r c lo s ed (Du P o n t t y p e ) can b o th b e u s ed f o r p r e - t r ea tm en t . In

the Becco type (F ig . 7 -11) , the c lo th i s p i led co ld in to the top and i s hea ted as i t

p a s s e s d o w n t h r o u g h t h e b o x b y s t e am a n d p a s s e d t h r o u g h t he p e r f o r a te d p l a t e s

a r o u n d th e b o x , j u s t b e lo w th e t o p o f t h e p il e . T w o h ea t i n g p o s i t i o n s a r e p r o v id ed ,

t h e l o w er o n e f o r u s e w h en th e b o x i s b e in g f il led . In th e Du P o n t t y p e o f J - Bo x

u n i t s (F ig . 7 -1 2 ) , t h e f ab ri c p as s es t h r o u g h th e l o n g en t e r in g b o x w h ich e n ab l e s t h e

f ab r ic ro p e t o r each t h e d es i r ed t em p er a tu r e (98~ b e f o r e p i l i n g d o w n in to t h e t o p

o f th e J - B o x i ts e lf . T h e i n t e r n a l s u r f ace o f t h e en t ir e J - Bo x i s g r o u n d v e r y s m o o th

to av o id an y f r i c t i o n o n t h e m o v in g c lo th . T h e m a te r i a l o f co n s t r u c t i o n o f J - Bo x

s h o u ld b e h ig h q u a l i t y s t a in le s s s t ee l f o r p e r o x id e t r ea tm en t , f i b r e g l a s s re in f o r ce -m en t p l a s t i c f o r h y p o ch lo r i t e t r ea tm en t , s t a in l e s s s t ee l w i th t i t an iu m co m p o n en t




F igur e 7 - 13 . Op e r a t ing se que n c e o f a th r e e - s t a ge r ope r a nge .w a s h ) r o p e r a n g e s e q u e n c e i n a c o n t in u o u s J - B o x e s b l e a c h i n g p l an t . T h e e n e r g y

c o n s e r v a t i o n i s a m a j o r f a c t o r in m u l t i- s t a g e p r o c e s s i n g a n d h e n c e c o n s i d e r a b l e

i m p o r t a n c e h a s b e e n g i v e n to t h e d e v e l o p m e n t o f m o d i f i ed r o u t e s, f ir st b y c o m b i n -

ing sc our ing wi th de s i z ing o r b l e a c h ing . F ig . 7 - 14 shows the Du Pon t two- s t a ge

(s inge --~ des ize - -~ scou r & bleac h ~ w ash) b leach ing range . In th is range the c lo th

in r ope f o r m i s s a tu r a t e d wi th 2 .5 - 4% c a us t ic soda so lu t ion a t 30 ~ a nd squ e e z e d to

10 0 % p ic k - up . Th e c lo th i s t he n r a p id ly he a te d to 10 0 ~ a nd p i l e d in J -B o x f o r

a b o u t 1 h . T h e g o o d s a r e t h e n s a tu r a t e d w i t h 0 .5 -1 v o l u m e p e r o x i d e s o l u ti o n o f p H

10 .6 to 10 .8 in p r e se nc e o f sod ium s i l ic a t e ( 1 - 1 .6 %) . T he f a b r ic a f t e r squ e e z ing i s



2 2 6 B l e a ch i n g a n d W a s h i n g E q u i p m e n t

F igu r e 7 - 14 . Du Pon t c o n t inuou s tw o- s t a ge b l e a c h ing r a nge [ 16] .

onc e a g a in he a te d to 10 0 ~ in the he a te r t ube a nd s to re d f o r 1 h in J - B ox . Go ods

c on ta in ing dye d ya r n a r e he a te d a t s l i gh t ly lowe r t e m pe r a tu r e . F ina l ly , the goo ds

a r e wa sh e d in a r ope w a she r . B le a c h ing w i th hypoc h lo r i t e c a n a l so be done us ing J -

B ox sys t e m wi th sa tu r a to r . The f a b r i c a f t e r s a tu r a t ion wi th hypoc h lo r i t e so lu t ion

c on ta in ing 0 .7 5 g /1 non - ion ic w e t t ing a ge n t a nd 0 .25 g/1 o f 15% c he m ic a t r oom

te m pe r a tu r e a r e p i l e d in to J - B ox f o r 15 - 40 m in a t 6 0 -10 0 ~ a nd the n wa she d . The

two - s t a ge p l a n t w i th a spe e d o f a bou t 100 yds /m in r e qu i r e s t r e a tm e n t o f a bou t 2 ha nd a l so p r ope r t im e a nd pH i s r e qu i r e d to be m a in ta ine d to c on t r o l t he r a t e o f

r e a c t io n w h i c h m a y d a m a g e t h e c lo t h. T h u s , i n o n e -s t a g e c o n t in u o u s r o p e b l e a c h -

ing ranges (Fig . 7 -15) , one more s tage i s e l imina ted and the good s a re caus t ic t r ea ted

F igur e 7 - 15 . One - s t a ge c on t inuous r ope b l e a c h ing r a nge us ing

J - B o x ( C o u r te s y o f F r i e d r i c h s f e l d G m b H , G e r m a n y ) .

a nd b le a c he d in one ba th . The sod ium c h lo r i t e m e thod i s o f t e n the on ly f e a s ib l e



B l e a c h i n g a n d W a s h i n g E q u i p m e n t 227

pr oc e d ur e f o r b l e a c h ing b le nds o f c o t ton a nd syn the t i c f ib r e s by one s t a ge sys t e m .

The we t t ing a nd r in s ing un i t ( 1 ) i s m a de up o f th r e e c om pa r tm e n t s , e a c h wi th i t sown sque e z ing un i t . B e f o r e e n te r ing the ne x t s t a ge the goods a r e de pos i t e d on a

c hu te ( 2 ) c oa te d wi th PTF E in the im p r e gna t ing m a c h ine ( 3 ), li quor up ta ke i s ke p t

c ons ta n t a t a bou t 30 % by m e a ns o f sque e z e r o l l e r s . The im pr e gna t ing l iquor i s

c i r c u la t e d a nd f i l t e r e d c on t inuous ly , a nd the c onc e n t r a t ion o f c he m ic a l s i s m e a -

su r e d a nd toppe d up a u tom a t i c a l ly ( 4 ). I n the he a t ing up a nd sh r inka ge un i t ( 5 ) the

goods a r e he a te d to 9 8~ by sp r a y ing w i th sa tu r a t e d s t e a m a nd p i l e d in to the J - B ox

( 6 ) . Af t e r e x i t ing f r om the J - B ox , the goods a r e c onve ye d loose ly a nd wi thou t

c r e a s ing to a wa te r a nd ne u t r a l i s ing ba th by a w inc h f o r m ing pa r t o f t he wa sh ing

a nd ne u t r a l i s ing se c t ion ( 7 ). The r ope i s sque e z e d on ly whe n c o o le d a nd the n de -

pos i ted in another in te rm edia te s tore (8 ). The fo l low ing sec t ion o f the range i s used

to a pp ly f luo r e sc e n t wh i t e n ing a ge n t s a nd a l l c om pa r tm e n t s a r e f i t t e d w i th the i r

own squeeze uni ts . On leaving the range , the rope i s p i led in to a t ro l ley (10) for

loa d ing in to a c e n t r i fuge . The c o nc e n t r a t ions o f b l e a c h ing b a th a r e g ive n in Ta b le

7 .2 . I f hy dro gen p erox ide i s used as a b leac hing agent , the fabr ic i s sa tura ted wi th a

T A B L E 7 . 2R e c i p e f o r O n e - S t a g e B l e a c h i n g w i t h S o d i u m C h l o ri te

Add i t ive s C o t ton Po lyno s ic /C o t ton Po lye s t e r /C o t ton

Sodium chlor i te (80%) , g /1

Blea chin g au xi l ia ry , g/1

pH ( wi th f o r m ic a c id )

J - B o x d w e l l p e r io d , m i n

12-20 12-15 10-12

5 5 5

3.8 3.8 4.0

90-105 60 60

so lu t ion c on ta in ing H202, wet t ing agent , sodium s i l ica te , caus t ic soda , sof teners

a nd wh i t e n ing a ge n t s . The p r oc e ss , ope r a t e d by two m e n a t up to 20 0 yds /m in c a n

turn out about 10 ,000 yds of fabr ic an hour .

I n the c a se o f kn i t t e d goods , pe r ox ide b l e a c h ing on e ithe r FM C we t bo t tom

J- B ox ( F ig . 7 - 16 ) o r on the Ga s ton C oun ty DuB e c sys t e m ( F ig . 7 - 17 ) a re su i t ab le .

S uc h ra nge s ( F ig 7 - 16 ) c ons i s t o f a n unw ind c r a d le , a s e wing sc r a y , a d r y sto r a ge

J - B ox , ho ld ing a bou t 9 0 0 kg o f tubu la r f a b r i c, a s a tu r a to r, a b l e a c h J - B ox a nd a

wa she r . The FM C sys te m ha s a we t bo t tom c r e a te d by ha v ing a 540 li tr e he e l t a nkof l i quor, w h ic h i s m a de by d r op p ing 27 0 l i tr e o f t he sa tu r a to r l i quor to it , m a k ing



2 2 8 B l e a c h in g a n d W a s h i n g E q u i p m e n t

F ig u r e 7 - 1 7 . T h e Gas to n Co u n ty Du Bec s y s t em .

u p t o 5 4 0 l i tr e w i th w a te r an d c i r cu l a t i n g t h e li q u o r b y m ean s o f p u m p in s id e t h e J -

Bo x . In co n t r a s t , i n t h e Du Bec s y s t em (F ig . 7 - 1 7 ), t h e b l each in g J - Bo x h as a

P T F E l i n in g an d th e w a s h e r is a s p i ra l r o p e w as h e r . T h i s d r y st o r ag e J - Bo x i s r u n20% fas ter than the wet J -Box and any var ia t ion in load in the sys tem i s accom odated




w i t h c o m p e n s a t i n g o r b a l a n c e d s c r a y s . T h e D u B e c r a n g e c o m b i n e s t h e b e s t fe a -

t u re s o f t w o w e l l -k n o w n p r o c e s s e s : t h e D u P o n t s i n g l e s ta g e m e t h o d a n d t h e B e c c oW e t h e e l J - B o x m e t h o d . C a p a c i t y o f t h e D u B e c ' s J - B o x is 3 , 00 0 p o u n d s . R a n g e

s p e e d s f ro m 5 0 t o 1 5 0 y d s / m i n w i t h a p r o d u c t i o n a v e r a g e s o f a b o u t 2 00 0 lb s /h .

The J - B o x r e c ipe s f o r the two type s a re c om pa r e d in Ta b le 7 .3 . Ko lm e r de sc r ibe s

T A B L E 7 . 3

J - B o x R e c i p e s ( 1 00 % P i c k - u p , S t e a m 9 0 M i n u t e s a t 9 0~

C h e m i c al F M C D u P o n t

W e t t ing a ge n t ( g /l )DTPA, 40 % ( g / l )

So diu m s i l ica te , 79~ (g /l )

S od ium hydr ox ide , 10 0 % ( g / l )

H202, 35% (ml/1)

5 51 1

10-20 10-20

7-10 4-7

45 45

a de v e lopm e n t o f t he Ga la xy wh ic h use s J - B oxe s f o r sto r a ge a nd wa she s the f ab r i c

a s a f l a t t e n e d " o p e n - w i d t h ' t u b e. E a c h s e c ti o n o f t h e w a s h e r ( th e T u b o l a v a r ) c o n -

s i s ts o f a sm a l l J -B o x in wh ic h the f la t t e ne d tube s a re sp r a y wa sh e d . O n e m e r g ing

f r om the J - B ox the tube i s i n f la t e d , t o a lt e r t he c r e a se loc a t ion , a nd n ippe d , be f o r e

go ing in to the ne x t s e c tion .

T h e f o l lw i n g a r e th e a d v a n t a g e s a n d d i s a d v a n t a g e s o f c o n t i n u o u s r o p e b l e a c h -

ing in J -Box : -

A d v a n t a g e s :

i) J - B o x o f f e r s e c on om y in spa c e , t im e , wa te r , s t e a m , a nd c he m ic a l s .

i i) M a te r i a l to l iquor r at io is 1 :1 . M in im um e le c t ri c a l pow e r i s r e qu i r e d w i th

a dv a n ta ge o f va r i a b le spe e d .

i ii ) U n i f o r m a n d r e p r o d u c i b l e a b s o r b a n c y w i t h g o o d w h i t e n e s s o f t h e g o o d s is

ob ta ine d .

i v) M i n i m u m h a n d l i n g d a m a g e w i t h l es s lo s s o f t e n s il e s t re n g t h is o b se r v e d .

v ) Fa br i c s o f d i f f er e n t w id th , we igh t a nd de ns i t ie s c a n be r un th r ough the p l a n t

wi thou t a l t e r a t ion o r a d jus tm e n t , e xc e p t f o r spe e d a nd dwe l l t im e a t e a c h

s t a ge o f the p r oc e ss .

D i s a d v a n t a g e s :

i) J - B o x sys t e m is e c ono m ic a l on ly i f t he p r odu c t ion ta r ge t i s b ig e nou gh to




f e e d the J - p la n t by a bou t 2 l a c s l i ne a r m e te r pe r da y . Howe ve r , sm a l l e r

un i t s ha ve a l so be e n de ve lope d f o r ha nd l ing 2 to 3 tons o f c lo th pe r da y .i i) P in ho le s - c a t a ly t i c a c tion o f i r on c om ing f r om s t ea m p ipe s i s obse r ve d

som e t im e s on the b l e a c he d f a b ri c .

i ii ) S om e s i l ic a t e s f r om the w e t c lo th c on ta in ing b le a c h ing so lu t ion m a y be

de pos i t e d on the he a te d wa l l s o f t he J - B ox . The c lo th s l id ing down the

J - B o x r ubs a g a ins t the se s i l i c a te s c a l e s tha t l e a d to a b r a s ion m a r ks w h ic h

s h o w s u p i n s u b s e q u e n t d y e in g .

iv) Du e to grea t w e igh t of the c lo th , the low er por t ion of the fabr ic is subjec ted

to g r e a t p r e s su r e , w h ic h m a y be up to 2 tons in l a rge r J - B oxe s . T h i s m a y

le a d to s e ve r e r ope m a r ks in c e rt a in c om pa c t a nd he a v ie r va r i e ti e s o f c lo th .

Co nt inuou s t rea tments in rope form a re a lso l ike ly to cause lengthw ise c rease

m a r ks .

7 .5 Cont inuous Open-W idth Bleach ing Equipm ent

Som e fabr ics such as heav y dr il l, co rded fabr ics, sa t ins and o the r sens i t ive weav es

a r e l i a b le to be da m a ge d i f t he y a r e b l e a c h e d in r ope f o rm . C r e a se le s s r unn ing a nd

low c lo th t e ns ion a r e a l so im p or t a n t f a c to r s f o r b l e nds w i th syn the t ic s . Th e se ne -c e s s it a te d t h e d e v e lo p m e n t o f n e w t y p e s o f o p e n - w i d t h b l e a c h i n g m a c h i n e r i e s f o r

f a b r ic s . Ge ne r a l ly , a c on t inuo us op e n- w id th b l e a c h ing r a nge c ons i s t s o f 2 to 3

u n i t s w i t h m a x i m u m s p e e d o f 1 0 0 t o 1 50 m / m i n a n d r e a ct i o n t im e o f a b o u t 2 -7 m i n

pe r t r e a tm e n t un i t. D i f f e re n t t ype s o f st e a m e r s c a n be c om bine d in va r ious w a ys to

f o r m a la r ge num be r o f d i f f e r e n t r a nge s , t o c a t e r f o r a b r oa d s pe c t r um o f r e qu i r e -

m ents in te rms o f prod uc t iv i ty , f abr ic qu a l i t ie s and su bseq uent t r ea tm ent [ 17 ,18]. I t

i s d i f fi c u l t t o e xp la in va r ious f a b r ic pa ths in d i f fe r e n t t ype s o f s t e a m e r s a nd s t e a m -

i n g o p e ra t io n s , h o w e v e r T a b l e 7 .4 m e n t i o n s s o m e o f t h em .

F o r c h e m i c a l p r e - t re a t m e n t o f w o v e n c o t t o n a n d p o l y e s te r /c o t t o n b l e n d e d f a b -

r ic s B e n n i n g e r h a s d e v e lo p e d th e " B e n B l e a c h s y s t e m " f o r d e s iz i n g , s c o u r in g a n d

b le a c h ing in one ope r a t ion i .e , " B e n - I n j e c t a " f o r de s i zing , " B e n - I m pa c ta " f o r im -

p r e g n a t i o n , " B e n - s t e a m " f or s te a m i n g a n d " B e n - E x t r a c t a " f or w a s h in g . F o l lo w -

ing de s i z ing in the " B e n - I n je c t a /B e n - Ex t r a c t a " s e c tion , t he f a b r ic is s a tu r a t e d and

l o a d e d w i t h b l e a c h i n g s o l u t io n s i n t h e " B e n - I m p a c t a " f o r h i g h d e g r e e o f p e n e t r a-

t ion and h igh fabr ic - liquor in te rchang e . Ben - Im pac ta (Fig . 7-18) i s in i ts geo m etryl ike a n ups ide down I n je c t a . The f a b r i c pa s se s th r ough two long na r r ow s lo t s , i n




T A B L E 7 . 4

D i f f e r e n t O p e n - W i d t h C o n t i n u o u s B l e a c h i n g S t e a m e r s [ 1 9]

M a n u f a c t u r e r N a m e Fe a tu r e s

Ar tos C o n t i n u o u s o p e n - w i d t h

s t e a m i n g m a c h i n e s w i th

A R T O X " R a p i d R e l a x " U - b ox

Ai r I ndus t r y R o l l - a - B e l t co m b i n a t io n s t e a m e r

B r u g m a n n

Esta fe t te

B e n n i n g e r

C o n v e y e r s te a m e r

T y p e D S c o m b i n a t i o n s te a m e r

G o l l e r C o n v e y e r s t e a m e r

K l e in e w e f e r C o m b i - s te a m e r b o x

M a t h e r & P l a tt V a p o r l o c R o l l e r -b e d

pr e s su r e s t e a m e r

( a) C a p a c i t y - 4 0 0 k g / m o f

fabr ic width .

( b ) R unn ing spe e d up to

10 0 m /m in .

(a) Tigh t - s t rand sec t ion-30 m.

(b) Co nv eye r capac i ty- 100 kg

o f f a b ri c p e r m e t e r o f

width .

C a p a c i t y - 3 0 0 0 m .

(a) Tigh t-strand section 50,100

o r 1 5 0 m .

(b) Roller-bed-Minimu m 7 ra in

dw e l l a t up to 150 m /m in .(a ) C a p a c i ty - 30 0 to 40 0 m

f a br ic pe r m e te r o f

conveyer .

(b) A range of conv eyer length

is ava i lab le .

(a ) T igh t - s t r a nd se c t ion 40 o r

8 0 m .

( b ) R o l l e r - be d - 4 0 0 to 60 0 kg

o f f a b ri c p e r m e t e r o f

fabr ic width .

(c) Reaction ti m e- 10 to 15 min.

(a ) D w e l l t i m e - 2 t o 3 m i n at

100 m /m in .

( b ) P r e s su r e - up to 30 p . s . i .

(c) Tem perature - up to 134~

wh ich the imp regna t ing l iquor c i rcula tes . Imp regna t ion a t 40~ is norm al wi th pe rox-




F igu r e 7 - 18. I m pr e gn a t ing un i t ( B e n- I m pa c ta ) f o r

p r e - tr e a t m e n t ( C o u r t e s y o f B e n n i n g e r A G ) .

ide , bu t w i th good s t a b i li s e r t he t e m p e r a tu r e c a n be r a i se d e ve n up to 6 0~ The

a dv a n ta g e s o f th i s t ype o f im p r e gna t ing u n i t ar e : sm a l l l iquor vo lum e , in t e ns ive

f a b r i c - l iquor in t e r c ha nge ove r a long r e a c t ion z one , va r i a b le l i quor a pp l i c a t ion ,

low c on sum pt ion o f c he m ic a l s , e ve n sa tu r a t ion a nd loa d ing , sm a l l spa c e r e qu i r e -

m e n t , n o s t r e a k i n e s s o r c r e a s e s a n d s e l f - r e g u l a t i o n o f li q u o r c o n c e n t r a t io n .

M oni t e r ing o f the l i quor c onc e n t r a t ion in the im pr e gna t ion un i t i s none sse n t i a l ,

e xc e p t a t m a te r i a l c ha nge ove r .

7 .5 .1 S t e a m e r s w i t h o u t p l a i t ed s t o r a g e

Figur e s 7 - 19 to 7 - 23 show the va r ious f a b r i c pa ths in c on t inuous ope n- wid th

bleach ing equ ipm ent wi th s teamer sys tems based on pos i t ive fabr ic guidence wi thout

p la i t e d s to ra ge . Th e m a in f e a tu r e s o f t h is sys t e m a re : ve r y m uc h su i t ab le f o r c r e a sesusc e p t ib l e f a b r ic , fa i r de g r e e o f wh i t e ne ss , fa b r ic w i th good a bso r ba n c y , l e ss

c ha nc e s o f f a b r ic de g r a da t ion a nd f a i r m o te r e m ov a l .

7 .5 .2 C o n v e y e r s t e a m e r w i t h o u t p r e - s t e e p i n g z o n e

C o n v e y e r s t e a m e r w a s f ir st d e s ig n e d b y M a t h i e s o n A l k al i C o r p o r a ti o n i n U S A

[20] . F igs . 7 - 24 to 7 - 28 show the l ine d i a g r a m s o f suc h c onve y e r s t e a m e r sys t e m s

ba se d on p la i t e d fa b r i c s to r a ge wi thou t p r e - s t e e p ing z one . Dur ing the e a r ly 60 s

s t e a m e r s we r e de ve lope d to t r e a t t he c lo th in ope n - wid th f o r m f o r ve r y sho r ts t e a m ing tim e ( 9 0 - 120 se c s ) a t 120 - 130~ unde r p r e s su r e f o r c on t inuo us sc our ing



B l e a c h i n g a n d W a s h i n g E q u i p m e n t 2 3 3

Fig . 7 -21 F ig . 7 -22 F ig . 7 -23

F i g u r e s 7 - 1 9 t o 7 - 2 3 . S t e a m e r s w i t h o u t p l a i t e d s t o r a g e . F i g u r e 7 - 1 9 . B a b c o c k K G ;

F i g u r e 7 - 2 0. B e n n i n g e r A G ; F i g u r e 7 -2 1 . K l i e i n e w e f e r s G m b H ; F i g u r e 7 -2 2 .

E . Kus te r s ; F igu re 7-23 . C ,m e z S . p .A .

a n d p e r o x i d e b l e a c h i n g [ 2 1 ] . T h e m a i n d i f f e r e n c e b e t w e e n t h e K l e i n e w e f e r s

( P r e s su r l o k ) a n d M a t h e r & P l a t t (V a p o r l o c ) sy s t e m s i s t h e m e a n s o f fa b r ic t r a n sp o r t.

Kl i ene w efe rs uses a t i gh t - s t rand des ign w hi l e Mathe r & P la t t uses a ro l l e r -bed sys t em .

T h e l a t t e r a l l o w g r e a t e r f l e x i b i l i t y in r u n n i n g sp e e d [ 2 2 ] . T h e r o l l e r s a r e p o s i t i v e l y

d r i v e n wh i c h p u sh e s t h e f a b r i c f o r wa r d . T h e t i m e f o r s t o r a g e v a r i e s f r o m 7 t o 1 5

m i n o r m o r e . T h e e n t i r e s e t o f r o l l e r s is p l a c e d i n a s t e a m i n g c h a m b e r . T h e f a b r ic

c o n t e n t i s a b o u t 6000 m a t a p r o d u c t i o n sp e e d o f a b o u t 1 00 m / r a i n . T h e f a b r i c i s

s e n s i t i v e to c r e a s i n g o wi n g t o t h e ti g h t l y c o m p r e s s e d c l o t h p i le s w i t h i n t h e s t e a m e r .

T i g h t - s t r a n d s t e a m e r s w i t h a r e a c t i o n t i m e o f 1 t o 2 r a i n a n d wi t h o u t a n y p l a i t i n g o r

b a t c h i n g a v o i d a b o v e d i f f i c u l t i e s . H o we r e r , t h e se u n i t s a r e n o t su i t a b l e f o r f a b r i c

c o n t a i n i n g s e e d h u s k s w h i c h a r e , e v e n o t h e r w i s e d i f f ic u l t t o r e m o v e [ 2 3] .

I n t h e m u l t i l a y e r c o n v e y e r s t e a m e r ( F i g . 7 - 2 9 ) t h e c l o t h i s b l e a c h e d b y





Bleach ing and W ash ing Equ ipmen t 235

Fig. 7-32 Fig. 7-33

Figures 7-30 to 7-33 . Conveyer s teamers wi th pre-s teeping zone. F igure 7-30.

Ba bcoc k KG ; F igu re 7 -31 . S i r J ames Farm er N or to n ; F igu re 7 -32 . Kle inew efe r s

Gm bH ; Figure 7-33 . Ma ther & Pla t t L td .



2 3 6 B l e a c h i n g an d W a s h i n g E q u i p m e n t

a b l e fo r c r e a s e s e n s i t ive f a b r i c s , f a ir de g re e o f w h i t e ne s s , be t t e r a bs o rba n c y , l ow

D P v a l u e s a n d f a ir s e e d h u s k r e m o v a l . S u c h s t e a m e r s a ls o h a v e t i g h t -s t r a n d s e c ti o no f 4 0 - 8 0 m w i t h a r o l l e r - b e d o f a b o u t 4 0 0 - 6 0 0 k g o f f a b r i c p e r m e t e r o f f a b r i c

w i d t h w i t h a r e a c t i o n t i m e o f 1 0 t o 15 m i n u t e s .

7 . 5 . 4 P r e s s u r e l e s s o r c o m b i - s t e a m e r s

T h e c o m b i - s t e a m e r s a r e a s s o c i a te d w i t h h o r i z o n t a l ly l a id o u t p o s i t i v e l y d r i v e n

r o l l e r - b e d a n d a h e a t i n g - u p a n d r e a c t i o n z o n e w h i c h i s j u d i c i o u s l y c o m b i n e d . T h e

t i g h t - s t r a n d f a b ri c t r a n s p o r t h a s t h e o b j e c t o f e n s u r i n g u n i f o r m s w e l l i n g o f c e l lu l o -

s ic f i b r es . H e re t he f a b r ic i s s ub j e c t e d t o le ng t hw i s e t e ns i on a nd t he ro l l e r s s i mu l -

t a ne ou s l y e xe r t a n ir on i ng e f f e c t w h i c h l e ve l s ou t in t e rna l te ns i on w i t h i n t he f a b ri c

d u r i n g t h e t r e a t m e n t . T h e p l a it i n g d o w n s y s t e m o n t h e c o n v e y e r b e l t o r r o l l e r - b e d

of f e r s f l e x i b i l i ty a s fa r a s t he r e a c t i o n t i me s a re c onc e rne d , a nd a l l ow s p rodu c t i on

s p e e d s u p t o 1 5 0 m / m i n . S o m e t y p i c a l c o m b i n a t i o n s t e a m e r s a r e s h o w n i n

F i g s. 7 - 3 4 to 7 - 3 7. O n e - s te p c o n t i n u o u s b l e a c h i n g r a n g e w i t h m a x i m u m i m p r e g n a -

F i g u r e 7 -3 5 . F a r m e r N o r t o n c o m b i n a t i o n s t e a m e r .



Bleaching and W ashing Equipm ent 237

Figure 7-38. One-s tep cont inuous b leaching range using com bi-s teame r

(Courtesy ofEx clusiv as TEPA S.A.).

mum impregnat ion (1) i s a combinat ion of spraying and vacuum ext rac t ion by




w hic h the f a b r ic a t t a in s a p r e v iou s r e s idua l m o i s tu r e o f 35 - 55%. The f a b r ic i s the n

p a s s e d t h r o u g h P a d - S t e a m b l e a c h i n g s t e a m e r , " c o m b i " t y p e ( 2) w i t h u p p e r fa b ri cp a s s a g e b e t w e e n r o l l e rs a n d l o w e r r o l l e r- b e d f o r l o n g b a tc h i n g . T h e w a s h i n g u n i t s

( 3 ) a t t he e nd o f the s t e a m e r c om ple te s the r a nge .

I n a l l t ype s o f c om bi - s t e a m e r s the f a b r i c e n te r s th r ough a n a i r - loc k wh ic h i s

f o l low e d by he a t ing - up z one a t 100 ~ f o r a bou t 15 - 20 m in . F r om the e x t r e m e e nd

of the s t e a m e r the f a b r ic i s c a r e f u lly l e d ou t o f t he m a c h ine th r ough the de l ive r y a i r-

loc k. Th e t igh t - s tr a nd s t e a m e r se c t ion o f the c om bi - s t e a m e r i s a s se m b le d on a m odu -

l a r p r inc ip le . E a c h m odu le ge ne r a l ly ha s a f ab r i c c on te n t o f 50 m e te r s . Th e p r ob -

l e m o f c r e a se m a r k ing i s al so e l im ina te d in a ll t ype s o f f ab r i cs .

7 .5 .5 Cont inuous submerged b leach ing sys tem

T h e c o n t i n u o u s s u b m e r g e d b l e a c h i n g p r o c e ss i s al so k n o w n u n d e r t h e d e s ig n a -

t ion PKS ( pe r ox ide c on t inuous r a p id b l e a c h) p r oc e ss [24 ]. The ho r i z on ta l s to r a ge

c ha m be r a nd the c on t inuous PKS r a nge a r e shown in F igs . 7 - 39 a nd 7 - 40 r e spe c -

F igu r e 7 - 40 . C on t inuous , subm e r ge d , ope n- wid th PKS r a nge .

t ive ly . A he a d o f the s to r e (F ig . 7 -39 ) i s a n im pr e g na t ing pa d de r to a pp ly va r ious




l iquor s r e qu i r e d . Af te r pa dd ing , t he f a b r i c i s r un o ve r a gu ide r o l l e r i n to the e n t r y

s lo t a nd pa s se s th r ou gh a ho t a que ou s b l e a c h l iquor w h ic h a l lows b le a c h ing f o r 15 -

20 m in a t 9 5 - 98 ~ The l iquor w h ic h is c on t inu ous ly c i r c u la t ing a nd ove r f low ing

in the p r e - c h a m be r , sw e e ps the fa b r i c ge n t ly a nd wi thou t t e ns ion in to the ho r i z on-

t a l s to r a ge c ha m be r , w h ic h i s c lo se d a t t op a nd bo t tom by a spe c ia l c onv e ye r g r id

tha t i s d r ive n by m e a ns o f c a m - sha f t . A t e a c h r e vo lu t ion o f the sha f t t he f a b ri c ,

wh ic h i s p l a i t e d down in f o lds , a dva nc e s a g ive n d i s t a nc e . Th i s c onve ye r g r id i s

f i t t e d a bove a nd be low the s to r a ge c ha m be r to e na b le a l l k inds o f goods to be

t r e a te d . P a r t o f the c i r c u la t e d l iquor i s f e d to the g oods r un n ing ou t so a s to p r e ve n t

c r e a se s ow ing to ove r - r a p id c oo l ing in the p l a i t e d s t a te . B e c a us e the dwe l l oc c u r s

unde r the b l e a c h l iquor su r f a c e , t he p r oc e ss i s a l so r e f e r r e d to a s " unde r l i quor

b le a c h" . B a ye r f o l lowe d the i r o r ig ina l r e po r t s w i th o the r s [25 - 28 ] . A r e c ipe f o r

r e se r v io r i s g ive n in Ta b le 7 .5 a nd the e c onom y o f the p r oc e ss i s r e v ie we d [29 ] .

T A B L E 7 . 5

P K S B l e a c h i n g R e c i p e s f r o m B a y e r a n d M e n z e l [ 3 0]

C h e m i c a l B a y e r M e n z e l

Org anic s tab i l i se r (g / l )

So diu m s i l ica te , 79~ (g / l)

W e t t ing a ge n t ( g /l )

De te rgent (g / l )

S od ium hydr ox ide ( so l id , g / l )

H202, 35% (ml/1)

M i n i m u m d w e l l t i m e ( m i n )

T e m p e r a t u r e (~

6 5

7 6

- 1

2 1

4 4

20 10-17

10-15 20-40

95 85

The f a b r ic l e a ve s the s to r e v i a a r e gu la to r a n d a pa i r o f sque e z e r o l le r s , t he n r uns to

a w a sh un i t a nd b le a c h ing c a n be m a de in to a c on t inuous p r oc e ss ( F ig . 7 - 40 ). The

u s e o f t o w e r w a s h i n g u n i ts , w h i c h w o r k a c c o r d i n g t o a p u re c o u n t e r c u r r e n t p r i n -

c ip l e c a n sa ve w a te r du r ing wa sh ing . K~ a 's te rs [28] a dd i t iona l ly r e c o m m e nd e d a

s t e a m ing s t a ge f o r the f a b ri c e m e r g ing f r om the r e se rv io r , be f o r e w a sh ing a nd d r y -

ing . In 19 86 , He e t j a n s [31] a nd W i t t e [32 ] a nno unc e d the e n t r y o f Th ie s in to the

PKS m a r ke t . I t i s c l a im e d to p r odu c e 40 0 - 50 0 kg /h a t a r unn ing spe e d o f 40 m /m in .

T h i s m a c h i n e i s v e r y g o o d f o r th e b l e a c h i n g o f al l t y p e s o f w o v e n a n d k n i t te d



240 B l e a ch i n g a n d W a s h i n g E q u i p m e n t

f a b r i c s o f na t u r a l a nd s yn t he t ic f i b r es a nd t he i r b l e nds , a s w e ll a s f o r t he b l e a c h i ng

of c o l ou re d w ove n goods a s ve ry l i t t l e t e ns i on i s a pp l i e d . A dva n t a ge s c l a i me d fo r

th i s pro ces s a re 9m i n i m u m c h e m i c a l d a m a g e , s h o r t b l e a c h i n g t i m e a t a n a v e r a g e

l iquor ra t io of 15 91 , l ow ma c h i ne ry c os t s a nd good s h r i nka ge va l ue s . The ma i n

d i s a dva n t a ge i s t he b l e a c h i ng c he mi c a l c os t .

7 .6 W ashing EquipmentW a s h i ng i s c a l l e d fo r at al l st a ge s o f te x t i le p roc e s s i ng , i n p r e - t r e a t m e n t , a f t e r

dye i ng a nd p r i n t i ng , a f t er r e s in f i n i s h i ng e tc . The a i m i s t o r e mov e i mpur i t i e s , s iz e ,

s o f t e n i ng a ge n t s , l ye, de g ra da t i on p roduc t , r e s i due s o f a ux i l i a ri e s , un f i xe d dye ,

t h i c ke n i ng a ge n t s u s e d i n p r i n t i ng e t c . A l l the s e s ubs t a nc e s m us t be w a t e r s o l ub l e

o r , w i t h t he a i d o f a dde d c h e m i c a l s , e m ul s i f ia b l e . F i g . 7-41 s how s t he s i tua t i on

F i gure 7 -41 . S i t ua t ion be fo re a nd a f t e r w a s h i ng [ 32 ].

A - Actu a l s t a te ; B - D es i red s ta te ;

1 - L i quor , 2 - Fa b r i c , 3 - Ex t r a ne ou s ma t t e r .

be fo re a nd a f t e r w a s h i ng . I n ge ne ra l t he w a s h i ng p roc e s s c a n be d i v i de d i n t o t h r e e

pha s e s 9 oos e n i ng o f e x t r a ne ou s ma t t e r , tr a ns f e r o f e x t r a ne ous m a t t e r a nd r e m ova l

o f e x t r a ne ou s m a t te r . I n the f i rs t pha s e t he e x t r a ne ou s m a t t e r mus t s w e l l a nd loos e n

a s qu i c k l y a s pos s i b l e . I n the s e c o nd pha s e t he ma t t e r i s t r a ns por t e d by d i f fus ion t o

t he l a ye r o f l i quor f l ow i ng n e x t t o t he s u r f a c e o f the t e x t il e s . I n the t h i rd pha s e t he

e x t r a n e o u s m a t t e r i s c ar r ie d a w a y b y t h e f lo w o f t h e w a s h i n g l iq u o r a n d t h e m o v e -

m e n t o f the go ods . I n a c t ua l p r a c t ic e a l l t he th r e e pha s e s a r e found t o ove r l a p .

W a s h i n g i s c h a r a c t e r i s e d b y m a x i m u m e f f i c i e n c y c o m b i n e d w i t h s i g n i f i c a n t s a v -




in g s i n w a te r , e l ec t ri c i ty , h ea t an d ch em ica l s . T h e e f f ic i en cy o f w as h in g ac t i o n i s

p r o m o t e d b y m e c h a n i c a l m o v e m e n t , l iq u o r f lo w i n g c o u n t e r t o t h e ru n o f t h e g o o d s ,

ef f ic ien t d r ives and con t ro ls , su i tab le f abr ic gu ides e tc . Tak ing a l l f ac to r s in to con-

s i d e ra t io n , t h e b e s t a v e r a g e c o n s u m p t i o n f o r m o d e m m a c h i n e s i s o f t h e o r d e r o f

a b o u t 4 - 6 k g w a t e r /k g g o o d s .

T h e f a b r i c c a n b e w a s h e d i n r o p e a n d o p e n - w i d t h f o r m . P o t e y e s , m a d e o f

p o r ce l a in o r s ta in l e s s s t ee l, a r e u s ed f o r d r aw in g t h e f ab r ic i n t h e ro p e f o r m f r o m

o n e s t ep to t h e o th e r . Op en - w id th w as h in g g iv es m o r e u n i f o r m r e s u l t s t h an d o es t h e

r o p e f o r m . F u r th e r m o r e , d e l i ca t e f ab r i c an d t ex tu r i s ed w o v en an d k n i t t ed f ab r i c s

n eed a v e r y s o f t t r ea tm en t d u r in g s co u r in g an d w as h in g . B o th t h e f o r m , t h a t is t h e

r o p e a n d o p e n - w i d t h w a s h i n g c a n b e d o n e i n b a t c h w i s e o r c o n t i n u o u s f a s h i o n .

M a n u f a c t u r e r s a l l o v e r t h e w o r l d h a v e m a r k e t e d a n d e s t a b l i s h e d t h e i r r o p e a n d

o p en - w id th w a s h in g m ach in e r i e s an d i t i s d i f fi cu l t t o d es c r ib e a ll o f th em , h o w ev er ,

a f ew o f t h em d es ig n ed o n d i f f e r en t p r in c ip l e s a r e d es c r ib ed .

7 .6 .1 R o p e w a s h i n g m a c h i n e s

The l ine d iag ram of t igh t rope w ash ing m achine i s g iven in F ig . 7 -42 . The m achine

F i g u r e 7 - 4 2. T i g h t r o p e w a s h i n g m a c h i n e .




c o n s i s t s o f t w o c a s t i ro n s i d e f r a m e s a n d a p a i r o f h e a v y a n d w i d e s q u e e z i n g b o w l s

(E). Th e bow l i s dr iven pos i t ive ly whi le the uppe r one ro ta tes by f r ic t iona l gr ippage .

Tw o r op e s o f c lo th a r e ge ne r a l ly wa she d a t a t im e . One r ope (J ) en te r s th r ough a po t

e ye ( I ), pa s se s in to the n ip o f the sque e z ing bow ls ( E), e n te r s the wa te r i n the

t r oug h ( A) , pa s se s u nde r the tr ough gu ide r o l le r s ( B ) a nd be tw e e n the pe gs ( D) a nd

the n pa s se s in to the n ip a ga in . P r e s su r e i s a pp l i e d by s im ple l e ve r ( F ) a nd we igh t

( G) . H i s t he ha ndwhe e l , L i s f u l c r um , M i s i n t e r na l ly th r e a de d b loc k a nd N i s

t h r e a d e d b a r . T h e p a s s a g e o f b o t h t h e r o p e s t h r o u g h t h e m a c h i n e c o n t i n u e s i n a

sp i ra l f a sh ion to the c e n t r e whe r e bo th the r ope s f ina l ly l e a ve the m a c h ine . T he t a nk

usua l ly r e c e ive s f r e sh wa te r (K) . The ou t pu t o f t he m a c h ine i s a bou t 250 to 350 m /

m in . Due to c ons ide r a b le t e ns ion on the f a b r i c , t h i s t ype o f m a c h in e i s u t i li s e d in

t h e c a s e o f m e d i u m o r h e a v y f a b ri c s.

I n the s l a c k r ope w a sh ing m a c h ine ( Fig . 7 -43) , the f a b r i c r ope i s a l lowe d to d r op

F igur e 7 - 43 . S la c k r ope wa sh ing m a c h ine .

d o w n t h e m a c h i n e t a n k a n d i s m a i n t a i n e d t h e r e f o r a c e rt a in a m o u n t o f ti m e i n a

re laxed form. T he fabr ic rope (K) ente r s the pot eye ( I ), passes be tw een the squeez ing

bow ls ( E) , ove r the w inc h ( F ) a nd the n in to the de e p t r ough ( A) wi th a s lop ing ba se

down whic h the c lo th f a l l s i n a s l a c k a nd s l igh t ly p l a i t e d s t a t e . The f a b r i c the n

pa sse s un de r a w ood e n gu ide ro l l e r (B ) , t he n upw a r d be twe e n the pe gs ( D). A pe g




r a i l (C ) i s fi t te d to p r e v e n t the e n ta n g le m e n t o f r ope s a n d the n pa s se s th r o ugh the

n ip a ga in . Thus , t he f a b r i c t a ke s a sp i r al pa th . The p r od uc t ion i s a bou t 150 m /m inw i th a n w a te r c o nsu m pt ion o f a bou t 6 to 8 l i tr e s /kg o f c lo th .

Ano the r type , na m e ly squa r e be a te r wa sh ing m a c h ine i s u se d m a in ly f o r wa sh ing

pr in t e d goods . T he be a te r r e vo lve s in a d ir e c t ion o ppos i t e to tha t o f t he c lo th so tha t

i t r e c e ive s a f l a pp ing m ot ion w h ic h be a t s o u t l oose pa r t i c l e s a dhe r ing to the f a b ri c .

The h igh spe e d r ope wa sh ing m a c h ine ( F ig . 7 - 44) o f f e r s e f f i c i e n t p r oc e s s ing

F i g u r e 7 - 4 4. H i g h s p e e d r o p e w a s h e r ( C o u r t e s y o f H e m m e r , G e r m a n y ) .

w i thou t c u m be r so m e th r e a d ing up . In th i s type the l iquor t r ough i s d iv ide d in to two

o r m o r e p a r t s o r s e c t i o n s b y m e a n s o f c le a r ly r o u n d e d r e m o v a b l e p a r t it io n s . T h e

f a b r ic i s f e d in to the m a c h ine f r om a su i t a b ly pos i t ione d po t e ye a nd f i rs t w a she d in

one s ide o f the pa r t i t ion a nd the n on the o the r s ide a nd so on . The wa sh l iquor i s

a r r a nge d to f low in a d i r e c t ion oppo s i t e to the f a b r ic r ope . The f a b r ic r ope pa s se s

a l t e r na t ive ly unde r a s t a in l e ss s t e e l bo t tom r o l l e r a nd a loose s t a in l e ss s t ee l bobb ins

on the top sha f t . A t the e nd o f the wa s h ing se c t ion , t he f a b r i c pa s se s th r ou gh

p n e u m a t i c a l l y l o a d e d s q u e e z e d e v i c e l o c a t e d a t t h e t o p . T h e m a c h i n e i s t o t a l l y

enc losed and f i tted wi th s l id ing g lass pane ls . The fabric is guided throu gh the ma chine

in suc h a m a nne r tha t l owe s t poss ib l e t e ns ion i s e xe r t e d on the f a b r i c . The h igh

p e r f o r m a n c e r o p e w a s h i n g m a c h i n e s m a y b e e m p l o y e d b o t h a s a si n g l e u n i t or in

c o n t i n u o u s o p e r a t io n w i t h s i m i l ar m a c h i n e w i t h a w o r k i n g s p e e d o f u p to 2 0 0 to

2 5 0 m / m i n .A f t e r ro p e w a s h i n g , t h e f ab r ic i s p a s s e d t h r o u g h t h e r o p e s q u e e z i n g m a c h i n e




( F ig . 7 - 45) wh ic h a l lows the f a b r i c to ha ve r e a sona b ly c ons i s t a n t wa te r c on te n t .

F igu re 7 -46 . A ca r r iage p i le r for fabr ics .

w h i c h m o v e f o r w a r d o r b a c k w a r d i n o n e d i r e c ti o n o v e r t h e r o p e o f p it s. T h e n t h e

f a b r ic i s ope n e d ou t f rom r ope to ope n w id th f o r m w i th the he lp o f a n ope ne r ( F ig .

7 - 47 ) o r s c u tc he r ( F ig . 7 - 48 ) . R ope e xpa nde r s o r r ope ope ne r s a r e u sua l ly f i t t e d



B l e a c h i n g a n d W a s h i n g E q u i p m e n t 2 4 5

F i g u r e 7 - 4 8. D i a g r a m o f s c u t c h e r fo r o p e n i n g c l o t h f ro m r o p e f o r m .

b e h i n d t h e r o p e w a s h i n g m a c h i n e s . I n t h e ca s e o f r o p e o p e n e r s w i t h o u t s c u t c h e r,

t h e f a b r ic r o p e s a r e o p e n e d w i t h th e a i d o f c l o th g u i d e r s a n d s o m e t i m e s a d d i t i o n a l

s c r o l l r o l l e r s a r e u se d . T h e s c u t c h e r u su a l l y c o n s i s t s o f a r e v o l v i n g b r a s s b e a t e r ,

t wo sc r o l l r o l l e r s , a p i v o t e d g u i d i n g d e v i c e a n d d r a w r o l l e rs . T h e t w o sc r o l l r o l l e r s

a r e g e a r e d t o g e t h e r b y m e a n s o f s p u r w h e e l s a n d a r e d r i v e n i n p a i r s i n t h e c o u n t e r

d i r e c t io n t o t h e c lo t h w h i c h p a s s e s b e t w e e n t h e m . T h e b e a t e r i s a l so d r i v e n i n th e

o p p o s i t e d i r e c ti o n o f t h e c lo t h . F o r b o t h t h e sy s t e m s , a n a d e q u a t e u n h i n d e r e d f e e d i n g

d i s t ance o f a t lea s t 6 -8 m i s nec essa ry to ensure tha t t he fabr ic rope c an be s uf f i c i en t ly

d e t w i s t e d . O c c a s i o n a l l y r o p e d e t w i s t e r s a r e f it te d b e t w e e n t h e l a s t r o p e g u i d e r in go r w h e e l a n d t h e r o p e o p e n e r . S c a n n e r s s e n s e t h e d ir e c t io n o f tw i s t o f th e r o p e a n d




a p p r o p r i a t e s i g n a l i s g i v e n t o t h e c o n t r o l l e l e m e n t . S o m e t i m e s " W h i t t l e r " r o p e

o p en e r s a r e f i tt ed w i th t h e s cu t ch e r an d t h e p a r t i cu l a r ly g o o d o p en in g e f f ec t is d u e

to th e f ac t th a t th e f ab r ic r o p e i s s u b j ec t ed t o a r h y th m ica l u n d u la t i n g m o v e m en t o f

th e tw o , t h r ee , o r f o u r p a r t s cu t ch e r , w h ich cau s es t h e r o p e t o l o o s en u p an d d e -

c r eas e , an d ex i s ti n g tw i s t is e l im in a t ed . T h e e s s en ce o f t h e "W h i t t l e r " r o p e o p en e r

i s, h o w e v e r , t h e r eg u l a to r (F ig . 7 - 4 9 ), w h ich k eep s t h e o p e n - w id th f ab ri c o n cen t r e

F ig u r e 7 - 4 9. Wh i t t le r r o p e o p en e r r eg u l a t c ~

an d g u id es i t t o f u r th e r p r o ces s in g o p e r a t i o n s . Mach in e s p eed s f r o m 1 2 0- 1 80 m /

m in can b e ach i ev ed i f t h e r eg u l a to r can f u lf il i ts t a s k in ev e r y r e s p ec t . W i th r o p e

o p en e r s o f o th e r d es ig n s m ac h in e s p eed s o f o n ly 4 0 -60 m / m in can b e a t t a in ed .

Af t e r l eav in g t h e o p en e r , t h e c lo th i s t h en p as s ed t h r o u g h h o t w a t e r i n w a te r

" - . . . .

1

F ig u r e 7 - 5 0. W ate r m an g le .




m ang le (F ig . 7 -50). The wa te r man g le r em oves l a s t t r aces o f d ir t, exces s w a te r,

rope m arks and f l a tt ens the f ab r ic . A w a te r mang le has 3 to 6 bowl s , bu t som et imeseven 8 . Th e m ang le i s equipp ed w i th an entry scaffo ld , an adjus table tens ioner , two

scrol l ro l l s and a utom at ic c lo th gu iders su i tab le for we t fabr ics a t the ent ry s ide and

a p i l i ng winc h a t the de l i ve ry s ide . The c lo th speed ranges f rom 100 to 200 m / min

depen d ing u pon the t ype o f the f ab r ic . The wa te r m ang le can be synchron i sed w i th

the d rye r , wh ich usu a l l y fo l lows t he w a te r man g l ing p roces s.

7 .6 .2 O p en - w i d t h w a s h i n g m a c h i n e s

Of the many open-wid th wash ing mach ine concep t s , t he t h ree d rum wash ing

ma ch ines , nam ely pe r fo ra t ed osc i l l a ti ng d rums , pe r fo ra ted d rum s w i th osc il la t i ng

cen t ra l un it s (Ro towa) , pe r fo ra t ed ro t a ti ng d rums and sp ray ing a r rangem en t s a re

very popu la r i n t he ba t ch fo rm. The more com m on type o f open-w id th con t inuous

wa sh ing m ach ine i s open soaper . Modi f i ca t ion fo l lowed m od i f i ca t ion i n wh ich t he

m anua l opera t i ons a re p rog res s ive ly m echan i sed , t he a im be ing t o co -o rd ina t e t he

indiv idual s teps. Di f ferent ef fective and inexpens ive sy s tems for w ashing even very

sens i ti ve w oven and kn i t ed go ods a re ava i lab l e .

In the suc t i on d rum wa sh ing m ach ine (F ig . 7 -51) t he s cour ing l i quor is d rawn

Figure 7 -51 . S uc t i on d rum w asher (Cour t esy o f Ar tos , Germ any) .




through the perfora t ions of the drums, and the fabr ic in ters t ices , thus ef fect ively

rem ov ing t he wa te r so lub l e ma te r ia l . S uc t i on d rum w ashers u sua l ly have two o rm ore bow ls d r iven a t some synchronous speed, the f ab ri c cover ing abou t 80% of

Figu re 7-52 to 7-56. Ty pical installations o fva riou s suction drum w ashing ranges [32].




the c i r cumference o f t he d rums . L iquor i s pumped ou t a t t he end o f t he d rum

(Fig . 7-51) and i s rec i rcula te d throu gh the washer . E dge unc ur lers are f i t ted beforethe f i rs t d rum on t he mach ine . A s imple n ip m ay be f i t ted be tween t he succes s ive

bowls . The funct ion of the n ip i s main ly to advance the fabr ic in to the uni t ra ther

than t o r em ove t he su rp lus li quor. The suc ti on d rum w ash ing m ach ine (F ig . 7 -52)

t rea t s the goods u nder low tens ion w i th a good con vect ive r ins ing act ion . The sam e

m achin e can be used in tende m w i th im pregn at ion squeeze ro l lers (Fig . 7-53) , wi th

imp regn at ion t roug h (Fig . 7-54) , wi th fes toon boi l ing off range fo l lowed b y r ins ing

t anks (F ig . 7 -55) , and spec ia l wash ing and bu lk ing m ach ine fo l lowed by r i n s ingtanks (Fig. 7-56).

In the Ro tow a w ashin g m ach ine (Fig . 7-57) the fabr ic i s w oun d on to the perfo-

F igure 7 -57 . Ro towa wash ing mach ine (Cour t esy o fHeber l e in & Co . AG) .

ra t ed beam on t he ba t ch ing t ro l ly . The range (F ig . 7 -58) com pr i ses w i th pe r fo ra ted

drum and l i quor c ir cu l a ti on , p lus a s soc i a t ed com bined w ind ing and w ash ing d r ive.

The fab r ic i s washed by pum ping l iquor t h rough the pe r fo ra t ed d rum . Th e l iqu id i s

forced f rom the cent re to the outer l ayer o f the fabr ic batch a t r ight ang les ensur ing

good washing ef fect l This process i s in tens i f ied by the cent r i fugal ac t ion of the

drum . W ork ing speeds range f ro m 20 to 140 m/ ra in . The range i s suppl ied in ro l ler

wid ths o f 1400 to 3600 mm . The wa te r c onsum pt ion i s 6 -8 1 / kg o f d ry goods . On

com plet ion of process ing , the chambe r is opened and the goods are reversed through

the squeezer o r f eed ro ll s and e i t he r wound up on to a g i an t ba t ch o r p la i t ed down .




1. Batc hing unit

2. Fabric

3. Ex pand er rol le rs

4 . S q u e e z e r w i th d - c m o t o r

5. Fal ler rol ler

6 . W i nd i ng a rm

7. d -c mot or wi nd i ng a nd wa sh i ng d r i ve

8. Hyd raul ic sys tem

9. Liquor rese rve

10. Ci rcula t ion pum p

Figure 7-58 . Rotow a open wid th wash ing r ange (Cour tesy o fH ebe r le in & Co. AG).

T h e s p r ay d r u m w as h in g m ach in e (F ig . 7 - 5 9 ) co n s i s t s o f s t a in l e s s s t ee l p e r f o -

r a t ed d r u m w h ich a l l o w s eas y w a s h l i q u o r t h r o u g h th e p e r f o r a ti o n s . T h e d r u m r u n s

i n b a l l b e a r i n g s m o u n t e d o u t si d e t h e ta n k . T h e m o v e m e n t o f t h e d r u m is b r o u g h t

ab o u t b y t h e d r ag o f th e r u n n in g f ab ri c . T h e w as h in g d r u m i s s e t in a s ta in l e s s s t ee l

t an k , w i th p r o v i s io n t o p r o p e r ly d r a in aw ay th e w a s h w a te r . A s e t o f n o zz l e b a t t e r -

i e s is p l ace d r o u n d th e c i r cu m f e r en ce o f t h e d r u m , w i th a v i ew to s p r ay w a te r j e t s

o n t h e f ab r i c . T h e j e t w as h e r (F ig . 7 - 60 ) co n s i s t s o f a t r o u g h an d a ca s cad e zo n e .

F ig u r e 7 - 5 9. W as h t an k w i th s p r ay d r u m . F ig u r e 7 - 60 . J e t w a s h e r (Co u r t e s y o f E .

Kt i s te r s , Germany) .

Ab o v e t h e ca s cad e zo n e , t h e r e is a n o zz l e w i th a w id e s lo t w h ich f o r m s a co n t in u -



B l e a c h in g a n d W a s h in g E q u i p m e n t 251

o u s c u r t a i n o f w a t e r a c r o s s t h e f u l l w i d t h o f th e g o o d s . T h e t r o u g h i s fi tt e d w i t h

f il te r a n d l i q u o r c i r c u l a t io n p u m p . W a t e r i s p u m p e d i n to t h e f a b r ic a t a h i g h s p e e d

v i a the w i de s l o t noz z l e . Th e c a s c a de z on e , a n inc l i ne d p l a ne , e ns u re s t ha t the w a t e r

f r o m t h e w i d e s l o t n o z z l e h a s t o f l o w t h r o u g h , a n d i n c o u n t e r c u r r e n t w i t h , t h e p i le .

T h e f a b r ic r u n s o v e r t h e d r u m a n d i s g u i d e d t o b e t a k e n a w a y f r o m t h e d r u m o v e r

s u i t a b l y p o s i t io n e d , e b o n i t e c o v e r e d , r o l l e r s ru n n i n g i n b a l l b e a r i n g s .

I n s o m e c a s e s a l o n g e r w a s h i n g t i m e w i t h s p r a y i s r e q u i r e d a n d t h i s c a n b e

a c h i e v e d b y u s i n g w a s h t a n k c o n t a i n i n g r o l l e r b e d a s s h o w n i n F ig . 7 - 6 1 . T h e f a b -

F i g u r e 7 - 6 1 . S p r a y w a s h i n g a n d s o a k ta n k r o l le r - c o n v e y e r .

r ic t r a n s p o r t i s e ff e c t e d b y m e a n s o f a p o s i t i v e l y d r i v e n s e t o f t r a n s p o r t r o l le r s . T h e

f i rs t r o l l e r pus he s t he c l o t h , t he s e c on d ro l l e r i n t u rn t r a ns po r t t he f a b r i c t o the t h i rd

ro l l e r a nd s o on . A bou t 150 t o 30 0 m o f f a b r i c i s p i l e d on t he ro l l e r c onve ye r i n

o r d e r t o a l l o w c o m p l e t e r e l a x a t io n o f t h e f a br ic . A p o w e r f u l s p r a y t h r o u g h t h e j e t i s

a r r a ng e d fo r a n e f f i c ie n t w a s h i ng o f t he f a b r ic , w h i l e t he fa b r i c is a de qu a t e l y s oa k e d

i n the ro l l e r be d . Th e f a b r i c i s l i f te d a nd l e d fu r t he r f rom t he w a s h i n g pa r t o ve r a s e t

o f g u i d e r o l l e r s a n d a s p e c ia l r o t a r y f a b r ic g u i d i n g d e v i c e .

T h e o p e n s o a p e r is th e c o m m o n t y p e o f c o n t in u o u s w a s h i n g m a c h i n e i n o p e n -




w id th f o r m (F ig . 7 -62 ) . T h e m ach in e co n s i s t s o f s ix o r m o r e co m p ar tm en t s o r

F i g u r e 7 -6 2 . C o n t i n u o u s o p e n - w i d t h w a s h i n g r a n g e

( C o u r t e s y o f F a r m e r N o r t o n , T y p e R - 1 6 ).

t an k s d ep en d in g u p o n th e p r o ces s e s t o b e ca r r i ed o u t. I t h a s a s e r ie s o f b o t t o m an d

to p r o l l e r s . T h e l o w er s e t i s u s u a l l y im m er s ed i n t h e w as h in g l i q u o r . T h e f ab r i c

p as s es o v e r t h e ad ju s t ab l e t en s io n e r s an d t h en o v e r an d u n d e r t h e g u id e r o l l e r s

w h ich g u id e t h e f ab r ic i n v e r t i ca l f o ld s t h r o u g h d i f fe r en t l i q u o r s i n th e t an k . T h e

f ab r ic i s s p r ay ed w i th w a te r f ro m th e s p u r t p ip es an d s q u eezed b e tw e en th e b o w ls

b e f o r e en t e r in g t h e n ex t tan k . T h e s p eed r an g e o f t h is m ach in e v a r i e s b e tw ee n 2 0 -

4 0 m / m i n d e p e n d i n g o n th e n u m b e r o f t a nk s . T h e e x e c u t io n o f t h e m a c h i n e m a y b e

o p e n a t t h e to p o r c l o se d d e p e n d i n g u p o n t h e e x p e c t e d p e rf o r m a n c e o f th e m a -c h i n e . I n s o m e m a c h i n e s t h e w a s h i n g t a n k s a r e f i t t e d w i t h s p e c i a l b e a t e r s

(F ig . 7 - 63 ) t o h av e m o r e e f f i c i en t w as h in g . T h e b ea t e r co n s i s t s o f co p p e r g u t t e r s

F ig u r e 7 - 63 . Bea t e r w i th f o u r s w iv e l l i n g g u t t e r s f o r w as h in g t an k s .



Bleaching and Washing Equipment 253

soldered on stiff steel rods, the ends of which are carried loose on spider wheels

keyed on beater shaft. Two sets each of three beaters are inserted between the foldsof the cloth and do not touch the fabric. The beater revolves at a great speed, so that

gutters are caused by the centrifugal force to fly out. They are partially dipped into

the water and give an elastic beating without rubbing. For soaping and washing of

delicate goods with a minimum tension, Aquatex soaper (Fig. 7-64) with expres-

Figure 7-65. Benninger Becoflex washing compartment.

processing goods of any width. Creation of turbulance in the wash tank by arrang-




ing inge ne ous f a b r ic pa s sa ge f o r wa r d a nd r e ve r se i s a n a dde d a dva n ta ge . S uc h un i t

i s a l so use d to r e m ov e a lka li f r om the m e r c e r i z e d c lo th . How e ve r , t h i s a r ra nge m e n ti s m o r e c o m p l i c a t e d a n d c o s t ly . T h e n e e d t o im p r o v e t h e w a s h i n g e f f ic i e n c y h a s

f u r the r l e d to the a dop t ion o f c oun te r - c u r r e n t f low , o f the wa sh l iquor , i n the wa sh -

ing c om pa r tm e n t ( F ig . 7 - 6 6) . Ve r t i c a l m e ta l p l a t e s s e pe r a t e the l i quor be tw e e n the

+."..............' C ~ (

~ : , k - L . . - . . " . . . . . . . . . . . " . . . . . 2 3 J

................( ~ - :.".i 7.,..-~"_...............................................................................................................

'i-~i%l~T~ .i.

|D R A I N

Figur e 7 - 6 6. C oun te r - c u r r e n t ope n- w id th wa sh in g un it .

m e ta l ro l le r s . Th e l iquor f low s in the d i rec t ion o ppo s i te to the fabr ic tr ave l e i the r by

c a sc a de a r r a nge m e n t o f t he se c t ions o r by a r r a ng ing ve r t i ca l pos i t ions in suc h a

m a nne r , t ha t the l i quor f lows in a s e r pe n t ine m a nne r . E a c h se pe r a t e suc c e ss ive im -

m e r s ion o f the f a b r ic i s i n a c le a ne r l i quor, w he r e a s the l i quor be c om e s inc r e a s ing ly

c on ta m ina te d a s i t a pp r oa c he s the d i sc ha r ge po in t , c lo se to the f a b r i c e n t r a nc e .

S i m i l a r a r r a n g e m e n t i s u s e d f o r w a s h i n g m e r c e r i z e d c l o t h i n c h a i n m e r c e r i z i n g

m a c h ine .

W a s h i n g c o m p a r t m e n t s w i t h a h o r i z o n t a l f a b r i c r u n h a v e b e e n p u r p o s e - b u i l t

dow n to the ve r y l a s t det a il . I n ho r i z on ta l f a b r ic l a ye r w a sh ing m a c h ine ( F ig . 7 - 6 7 ),

the f a b r i c e n te r s a t t he bo t tom a nd s t e pwise a sc e nds to the top . The d i s t a nc e be -

twe e n the tw o ve r t i c a l ba nks o f r o l l e rs i s a bou t 70 c m . W a sh ing i s done by m ul t ip l e

c oun te r - c u r r e n t p r inc ip le . The f r e sh wa te r e n te r s a t t he top , a nd a f t e r be ing e x -

p r e s se d a t t he top r o l l e r is c o l l e c t e d in the t r a y a nd f e d to lowe r on e s , t u r n by tu r n .

I n t e r m e d ia t e sque e z ing o f the f a b r ic a t t he e x t r e m e pos i t ions inc r e a se s the wa sh in g




q ]~ . ~

9 ~ , , - " , ~ " . .. .. ( ,, g. ..

......... ............... ! r

( % '- ~ ) ~ ......= = < t ! i

................................N ,t I ::

U / ~ I ~ |

\ .. ... . . . . . . ::I/I----

"63 i J l- . , '

. . ., ~ . ~, . ,, , ., , , ,~ . ~ - . . . .. . . .. . . .. . . .. . . . . . . . . " ~ /

" . '. . '; . " i # : : : : : : : : < : . ? ~ : : : . . : . : : : : : . : : : : : . : . : . = : . = . : . : : v . v : . " ' :. " . . . . . . . . . . . . . . . . . . . .. . . " ' " . . . . . . . . . . . . . . . .

Figur e 7 - 67 . Hor i z on ta l w a she r .

e f f i c ie nc y . E a c h wa sh in g un i t ho lds 24 m o f c lo th a nd f a b r ic c ha n ge s d i r e c t ion 12

t im e s . T h e m a c h i n e c a n b e c o u p l e d t o g e t h e r a s d u p l e x o r tr i p le x a s s e m b l y . W a t e r

c on sum pt ion i s a bou t 4 to 5 1 /kg o f f a b ri c . The ho r i z on ta l f a b r ic r un ha s f unda m e n-

t al a d v a n t a g e s b e c a u s e o f t h e a u t o m a t i c t w o - s i d e d t r ea t m e n t , b e n e f i c ia l c o u n t e r -

c u r r e n t f low wi th l i quor c i r c u la t ion , m or e e f f i c i e n t u se o f spa c e , u se o f g r a v i ty ,

c e n t r i f uga l f o r c e a nd gu ide r o l l e r w a sh ing a c t ion . P r ov id e d f u l l u se is m a de o f the

a v a i l a b le h e i g h t , h o r i zo n t a l f a b ri c g u i d e n c e e n b l e s 2 w a s h i n g c o m p a r t m e n t s t o b e

a r r a n g e d o n e a b o v e t h e a n o t h er . T h e t o p c o m p a r t m e n t c a n b e ru n w i t h f a b ri c a n d

l iquor in c oun te r - c u r r e n t , w h i l e in the bo t tom c om pa r tm e n t the l i quor i s c ir c u la te d .

Us in g th i s a r ra nge m e n t , r a d ial f low c a n be c om b ine d wi th the t a nge n t i a l f low a long

the f a b r i c su r f a c e e s se n t i a l f o r wa sh ing , a nd d i f f us ion c a n s t il l ta ke p l a c e .

T h e i m p o r t a n c e o f s q u e e z e ro l l er s f o r l iq u o r e x c h a n g e o n o p e n - w i d t h w a s h i n g

r a n g e s h a s b e e n d e m o n s t r a t e d b y m a n y m a c h i n e r y m a n u f a c t u r e r s . I n o n e s y s t e m

the goo ds a r e squ e e z e d o f f wh i l e ho t t o e xp lo i t t he lowe r v i sc os i ty o f wa te r. S p r a y

a s s e m b l y t o r e m o v e i n s o l u b l e i m p u r i t i e s f r o m t h e f a b r i c b y s w e e p i n g a w a y b y

k i n e t ic e n e r g y i s m e n t i o n e d . H i g h r a te s o f h y d r o e x t r a c t i o n a r e a c h i e v e d b y t h e



256 B l e a c h i n g a nd W a s h i n g E q u i p m e n t

R o b e r t o r o l le r p r in c ip l e . " B i c o f l e x " r o l le r p r o d u c e d b y K l e i n e w e f e r s - J a e g g l i / o f

Ge r m a ny i s de s igne d m o r e f o r un i f o r m e xpr e s s ion : a n a ir c ush ion in s ide the ro l l e rauto m at ica l ly adjus ts the pressure to ensure an uni form squeez in g e f fec t , even wi th

e x t r e m e ly na r r ow o r th i c k goods . I n the c onve n t iona l sqe e z ing un i t s p r e s su r e i s

a p p l i e d p n e u m a t i c a ll y o r h y d r a u l ic a l ly . H o w e v e r , i n t h e " A q u a p r e s s " s q u e e z in g

un i t ( Kus te r s ) p r e s su r e i s a pp l i e d hyd r os t a t i c a l ly i .e . by m e a ns o f a la r ge d i a m e te r

cyl inder f loa t ing on the l iquor . The n ip i s formed by th is f loa t ing ( s ta in less s tee l )

ro l le r and a dr iven co unte r - ro l le r . I t p rov ides even l ine pressure ove r the fu l l wid th

of the n ip . Th e ro l le r sur faces a re se l f -c leanin g in th is sys tem.

The de g r e e o f e xp r e s s ion l a r ge ly de te r m ine s the c os t o f d r y ing a f t e r wa r ds .

F ig . 7 - 6 8 shows a f e w c onve n t iona l hydr oe x t r a c t ion sys t e m s . The f loa t ing r o l l e r

. . . . . . . . . . . . . . . . . . . . i

!

P

,

2 " . - 6 .....3

, i . .. .. , ,, ! t . .. .. .. .. .. . : :; :. - . . . . . . . . . . . . . . . . ." . " ~ . . . . . . . . . . . ~ . .. .. .. .. .

Figur e 7 - 6 8. D i f f e r e n t t ype s o f hyd r oe x t r a c to r .

1 . Feed ro l le r , 2 . Hor izon ta l n ip , 3 . F loa t ing ro l le r ,

4 . Ro ber to squeeze ro l le r , 5 . Suc t ion device , P Force .

a r r a ng e m e n t ha s a l r e a dy be c om e a t r ad i t ion . G ood r e su l ts a r e a c h ie ve d wi th suc -

t ion o r o the r sque e z ing sys t e m s . S u c t ion sys t e m s a r e he a vy c onsum e r s o f e ne r gy .

C he m ic a l f in i she s ha ve t r a d i t iona l ly be e n a pp l i e d to the f a b r i c s u s ing im m e r s ion

(dip padd ing) o r low w et p ick-up techn iques such as l ick ro l l, porous bowls , va cuu m




e x t r a c t ion o r f oa m [33 ]. A l t e rna t ive m e th ods inc lude c oa t ing a nd la m ina i ton t e c h -

no log ie s [34 ] . I n the Ne x te c Ap p l i c a t ion p r oc e ss [35 ] ind iv idua l f ib r e s w i th in thef a b ri c a r e e nc a psu la t e d o r wr a p pe d wi th a n u l t ra - th in f i lm o f po lym e r . A sp e c ia l ly

de s igne d b la de s a r e u se d to she a r th in po lym e r c om pos i t ions in to f a b r ic s tha t a re

unde r t e ns ion . P r e - t r e a tm e n t o f t he f a b ri c , a nd po ly m e r se l e c t ion a r e u se d to in -

c r e a se the po lym e r f low a nd p r e ve n t s a tu r a tion o f the f ib r e s. On r e m ova l o f t he

she a r f o r c es , t he po ly m e r r e tu r n to a h ighe r v i sc os ity a nd the n the po lym e r i s c u r ed .

I t i s, thus , poss ib le to prov ide brea thable b a r r ie r f i lm as low as 100 nan om ete rs and

up to s e ve r a l m ic r ons w i th in the f a b r i c , p r e ve n t ing l iqu id wa te r f r om pe ne t r a t ing

whi l e a l lowing m ois tu r e va pour to pa s s th r ough to c lose to the sa m e r a t e a s the

o r ig ina l f a b i rc . Th i s t e c hn ique o f f ib r e e nc a psu la t ion p r oc e ss i s a l r e a dy be ing a p -

p l i e d on s i l i c one - ba se d po lym e r s , po lyu r e tha ne s , po lya c r y l i c s , spe c ia l ty ny lons ,

a n d o t h e r p o l y m e r s a n d m a y o p e n m a n y o p p o r t u n it ie s f o r e x p l o it a ti o n o f ch e m i c a l

f in i she s f o r p r ov id ing m ul t i - f unc t iona l f in ishe s on c o t ton f a b r i c s [34 ] .

R E F E R E N C E S

1 D .H . W yle s , Eng ine e r ing in Te x t i le C o lour a tion ., ed . C .Duc kw or th ( B r ad f o r d

: Dye r s C om pa n y Pub . T r us t , 19 8 3), C ha p te r 2 .

2 D. H. W yles , Rev. Prog. Colo ra t ion , 14 (1984) 139.

3 K. M cC on ne l , T ext i le Chem . Color . , 16 (6 ) (1984) 112.

4 Ano n, Text i l tech nic , 97 (1) (1979) 49 .

5 M. Sc hnie re r and E. Paul , Mel l ian d Text i lbe r . , 67 (1986) 248 .

6 M. Sch nie re r e t a l. , Tex t i l Praxis , 40 (1985) 49 .

7 D. Better , Texti l Praxis , 33 (1978) 163.

8 L . S c hwa r tz m a n , Am e r . Due s tu f f R e p . , 7 2 ( 4 ) ( 19 8 3) 45 .

9 I . Ho lm e , Text i le M on th (1988) 31 .

10 U. S. Patent , 2,029,985, Feb. 4, 1936.

11 U. S. Patent , 2,267,718, Oct. 30, 1940.

12 D.J . Cam bel l , Am er . Dye s tu f f Rep. , 33 (14) (1944) 293.13 E. E . Ru pp, Am er . Dy es t uf f Rep. , 31 (25) 1942.



258 Bleach in g an d W ash in g Eq u ip m en t

14 T. E. Be ll , Am er. Dy es tuf f Rep . , 31 (3) (1952) 80.

15 R .W . P inau l t , Tex t i le W or ld , No . 7 (1962) 220 .1 6 T . E . Be l l , En cy c lo p ed ia o f P o ly m er Sc ien ce an d Tech n o lo g y , "B leach in g

Te xt i l es " vo l . 2 , John W iley and Sons , N ew Y ork , 1985 , p 454 .

17 W . W eber , Int . Tex ti le Bu ll ., 1 (1979) 17.

18 B .D . B'~hr, J . C arbon nel an d P. Farber , Texti l Praxis Int l. , 46 (8) (1991) 780.

19 W . Prager , Am er . Dy estu f fR ep . , 67 (7) (197 8)24 , 48.

2 0 M a th ie so n Alk a l i W o r k s , Am er . Dy es tu f f Re p . , 3 3 (1 94 4 )5 3 6 .

21 Eas ton and Gal lahar , Am er . Dy estu f fR ep . , 53 (1954) 985.

22 C. Duc kw or th , Hors ley am d Thw ai tes , J . Soc . Dyers Colour is t s , 88 (1972)

281.

23 Ro we , Tex t i le Chem. Color . , 3 (1971) 170.

24 K. D. Bose , Mel l iand Tex t i lber ., 54 (1973) 391.

25 W . Guth , T inc tor ia (1975 )258 .

26 K. Ad rian, Texti l Praxis, 34 (1976) 7.

27 M enze l Mach i inenfabr ik , Tex t i lbe t r ich , 97 (8) (1979) 66 .~c

28 E . Kuste rs , Deutsch Faerb er - Kalende r , 32 (1973) 128 .29 E. Ehret , W irkere i und S tr ickerei Tec hnik, 6 (6) (1976) 364.

30 P . W urs te r , Tex t i lvered lung , 6 (1978) 223 .

31 J.P . D am broth , Int . Te xti le Bu ll , 4 (1976) 341.

32 A. Sch raud, Int. Te xti le Bull . , 4 (1974) 375.

33 M. Lew in , in Han dbo ok of F ibre Sc ience and Techn ology , Vol. II . Ch em ica l

Process ing o f F ibres and fabr ics , Part B, Funct iona l F in ishes , ed . M. Lew in

and S. B. S e l lo , N ew York : M arce l Dekke r , (1984) 1 .

34 I. Holm e, Colourage , Annual (1998) 41 .

35 A. R. Horrock s, Rev. Prog. Colora t ion, 16 (1986) 62.



Chapter 8

H E A T - S E T T I N G

8 . 1 I n t r o d u c t i o nFa br i c s p r od uc e d f r om syn the t i c f ib r e s o r f r om b le nds c on ta in in g l a r ge p r opor -

t ion o f suc h f ib r e s a r e no r m a l ly he a t - se t to s t a b i li s e the m . He a t - se t t i ng i s a he a t

t r e a tm e n t by w h ic h sha pe r e t e n t ion , c r e a se r e s i s ta nc e , r e s i l ie nc e a nd e l a s t i c i ty a r e

im par te d to the f ibres . I t a l so br in gs cha ng es in s trength , s t re tcha bi l i ty , sof tness ,

dye a b i l i t y a nd som e t im e s on the c o lou r o f t he m a te r ia l . A l l t he se c ha ng e s a re

c onn e c te d w i th the s t r uc tu ra l a nd c he m ic a l m o d i f i c a t ions oc c u r ing in the f ib r e . An

u n s e t p o l y e s t e r f i la m e n t y a m s h r in k s a b o u t 7 % w h e n a l l o w e d t o re l a x i n b o i l i n g

wa te r . Th is shr ink age i s abo ut 10% in the pres enc e of ca r r ie r a t boi l . I t i s , the re -

f o r e , ne c e s sa r y to c onf e r on f a b r i c som e de gr e e o f d im e ns iona l s t a b i l i t y in o r de r

tha t the ya r ns o r f a b r i c s r e t a in the ir sha pe du r ing su bse qu e n t p r oc e ss ing , w a sh ing

a nd i r on ing .

8 .2 T h e r m a l B e h a v i o u r o f S y n t h e t i c F ib r e s

S y n t h e t i c f i b re s , m a i n l y p o l y e s t e r a n d n y l o n , c o n s i s t o f l o n g c h a i n m o l e c u l e s

a nd a r e he ld toge the r by in t e r c ha in bonds . F ig . 8 - 1 shows how the c ha ins a r e J r -

\\ / "

j J / /

f

_1-

Figur e 8 - 1 . P r oba b le d i sa r r a y o f

p o l y m e r a f t e r s p in n i n g .

Figu re 8 -2 . Para l le l or ien ta t ion o f

c ha in m o le c u le s in d r a w n f ib re .

r e gu la r ly d i s t r ibu te d a t r a nd om in s ing le f ib re s im m e dia t e ly a f t e r sp inn ing . Thef ibres a re then s t re tched seve ra l t ime s the i r or ig ina l length to im par t des i rable prop -

e r t ie s to the f ib r e a nd th i s c a u se s o r i e n ta t ion o f c ha in m ole c u le s pa r a l l e l t o the f ib re

a x i s (F ig . 8 -2 ) . Th e s ing le c ha ins a r e no w he ld toge the r by in t e r m ole c u la r f o r c es ,

h y d r o g e n b o n d i n g o r b y a c o m b i n a t i o n o f V a n d e r W a a l s ' f o rc e s an d H - b o n d s . A s

a r e su l t o f s t r e t c h ing the f ib r e m ole c u le s c om e c lose r to e a c h o the r , r e su l t ing in

c l o s e r a l i g n m e n t , i n c r e a s e d d e n s it y a n d t h u s in c r e a s e d H - b o n d i n g . T h e H - b o n d s

a r e f o r m e d a t r a nd om a nd the r e a r e s t r a ins be twe e n the c ha ins . Th e s ing le c ha ins



2 60 H e a t - Se t t i n g

a re , h o w e v e r , n o t y e t c o m p l e t e l y s t r e t c h e d o u t a n d a r e s t il l k i n k e d h a v i n g a z ig z a g

c o n f i g u r a t i o n . I f e n e r g y in t h e f o r m o f h e a t i s su p p l i e d , th e c h a i n m o l e c u l e s s t a r tsv i b r a t i n g , s o m e o f t h e s e i n te r c h a i n b o n d s b r e a k a n d s o m e p a rt s o f t h e m o l e c u l a r

c h a i n s h a v e a g r e a t e r f r e e d o m a n d r e l a x . T h e t e m p e r a t u r e a t w h i c h t h e r e is c e r t a i n

i n c r e a s e i n m o l e c u l a r v i b r a t i o n o f p o l y m e r m o l e c u l e s d e p e n d s o n T g o f th e p a r-

t i c u l a r f ib r e . T h e h i g h e r t h e t e m p e r a t u r e t h e m o r e i n t e r c h a in b o n d b r e a k s a n d g r e a t e r

t h e r e l a x a t i o n , b u t c a r e h a s t o b e t a k e n n o t to h e a t th e f i b r e so a s to d a m a g e i t. T h e

s u p p l y o f e n e r g y i s s t o p p e d a s s o o n a s t h e m i n i m u m p o t e n t i a l e n e r g y i s r e a c h e d

a n d t h e f i b re s a r e c o o le d a s q u i c k l y as p o s s i b le , o n e s u c c e e d s i n " f r e e z i n g " t h e H -

b o n d s . T h e n e w l y f o r m e d b o n d s a r e m o r e d i f fi c u lt to b r e a k a n d t h e f ib r e s ar e

d i m e n s i o n a l l y s t ab l e an d w i ll n o t s h r in k a t a p p r o x i m a t e l y 1 0~ b e l o w t h e t e m p e r a -

t u r e o f s e tt in g . A t t h is j u n c t u r e t h e p r o c e s s t e m p e r a t u r e c o m m e n c e s t o p r o d u c e a

n e w h e a t m e m o r y a n d T g is c h a n g e d . T h u s t h e p r o c e s s o f t h e r m o s e t t i n g in s te n t e r

c a n b e b r o k e n d o w n i n t o f o u r d i s ti n c t p h a s e s :

i ) T h e g o o d s a r e r u n we t o r d r y i n t o t h e m a c h i n e a n d h e a t e d su p e r f i c i a l l y t o

t h e h e a t i n g t e m p e r a t u r e ( h e a t in g p h a s e ) .

i i) Th e hea t pen e t ra t e s the f ib re s un t i l l a l l po in t s , i ns ide and ou t , a re a t t hes a m e t e m p e r a t u r e ( p e n e t r at i o n p h a s e ).

i ii ) H e a t i n g o f t h e f a b ri c to a t e m p e r a t u r e w h i c h i s sp e c i f ic f o r e a c h f ib r e ,

e n s u r i n g b r e a k a g e o f i n t e r m o l e c u l a r b o n d s a n d e q u a l i s in g i n te r n a l s t re s s e s

( t r a n s i t io n a n d s t r e t c h p h a se ) .

i v ) C o o l i n g t h e f i b re r e su l t i n g i n t h e r e s t o r a t i o n o f i n t e r m o l e c u l a r b o n d s wh i c h

a r e f r ee f r o m i n t e r n a l s t r e s se s ( c o o l i n g p h a se ) .

8 .3 S t a g e s o f H e a t S e t t in g

H e a t - s e t t i n g c a n b e c a r r i e d o u t a t t h r e e d i f f e r e n t s t a g e s in a p r o c e s s i n g s e q u e n c e

i .e . in g r e y c o n d i t i o n ; a f t e r s c o u r i n g ; a n d a f t e r d y e i n g . T h e s t a g e o f h e a t - s e t t i n g

d e p e n d s o n e x t e n t o f c o n t a m i n a t i o n s a n d t y p e s o f f i b r e s o r y a m s p r e s e n t i n t h e

fabr i c .

I f h e a t - s e t t i n g i s c a r r i e d o u t i n t h e l o o m s t at e , m i n e r a l o i ls a n d n o n - i o n i c e m u l -

s i f ie r s c a n m o d i f y t h e f ib r e s t r u c t u r e a n d r u b b i n g a n d p e r sp i r a t i o n f a s t n e s s m a y b e

r e d u c e d d u e t o t h e so l u b i l it y o f d i sp e r se d y e i n th e c o n i n g o i l [1 - 4 ]. P V A s i ze a b o v e

1 3 5~ l o o s e s it s T g w h i c h is f o l lo w e d b y b e c o m i n g c r y s t a ll i z e d a n d m e l t s . T h eH - b o n d s , t h e r e f o r e , c a n n o l o n g e r b e b r o k e n w i t h t h e r e s u l t t h a t P V A b e c o m e s

d i f f i c u l t t o r e m o v e f r o m t h e f a b r ic . H o w e v e r , g r e y h e a t - s e t t i n g i s u se f u l i n t h e



H e a t -S e t t i ng 26 1

w a r p k n i t ti n g i n d u s t r y f o r m a t e r i a l s t h a t c a n c a r ry o n l y s m a l l a m o u n t o f l u b r i c a n t s

a n d f o r g o o d s t h a t a re to b e s c o u r e d a n d d y e d o n b e a m m a c h i n e s . T h e o t h e r a d v a n -t a g e s o f g r e y h e a t - s e t t in g a r e : y e l l o w c o l o u r d u e t o h e a t - se t t in g c a n b e r e m o v e d b y

b l e a c h i ng , f a b r ic i s l e s s s e ns i t i ve t o c r e a s e fo rm a t i on du r i ng s ub s e qu e n t p roc e s s i n g

etc.

H e a t - s e t t in g c a n b e c a r r i e d o u t a f t e r s c o u r i n g i f i t i s s u s p e c t e d t h a t t h e g o o d s

w i l l s h r i n k o r f o r t h e c l o t h i n w h i c h ' s t r e t c h ' o r o t h e r p r o p e r t i e s a r e d e v e l o p e d

dur i n g a c a r e fu l l y c on t ro l l e d s c our i ng p roc e s s . H o w e ve r , th i s s t a ge r e qu i r e s d ry i ng

t h e c l o t h t w i c e .

H e a t - s e t t i n g c a n be c a r r i e d ou t a ft e r dy e i ng a l so . Pos t s e t f a b r i c s s how c o ns i d -

e r a b l e r e s i s t a n c e to s t r ip p i n g c o m p a r e d w i t h t h e s a m e d y e i n g o n u n s e t f a b ri c . T h e

d i s a d v a n t a g e s o f p o s t s e t ti n g a re : y e l l o w c o l o u r d e v e l o p e d c a n n o t b e r e m o v e d a n y

m o r e b y b l e a c h i n g , h a n d l e o f th e c l o t h m a y g e t a lt e r e d a n d t h e r e is a r i s k o f c o l o u r s

o r o p t ic a l b r i g h t e n e r s b e f a d e d s o m e w h a t .

8 .4 M e t h o d s o f H e a t - S e t t in g

8 . 4 . 1 C o n t a c t m e t h o d

I n t h is m e t h o d t h e f a b ri c i s r u n i n c o n t a c t w i t h a h e a t e d m e t a l s u r fa c e . S o m em a c h i n e s a r e c o m p o s e d o f m e t a l ro l l e rs h a v i n g g a s fi re d c o r e s a n d a r e f il le d w i t h a

l i q u i d k n o w n a s d i a t h e r m t o u n i f o r m l y d is t ri b u t e t h e h e a t . S o m e t i m e s e n c l o s e d

r o l l e r s a r e h e a t e d w i t h h i g h t e m p e r a t u r e s t e a m . T h i s m e t h o d is m a i n l y u s e d f o r

h e a t - s e t t i n g o f p o l y e s t e r / c o t t o n b l e n d e d f ib r e f a b ri c s. T h o u g h h e a t i s u s e d e f f i-

c i e n t l y i n th i s m e t h o d , t h e w i d t h o f t h e f a b r ic s c a n n o t b e c o n t r o l le d w h i l e f a b r i c s

r u n f ia t a g a i n s t t h e r o l le r s u r f a c e s, a p a r t f r o m v a r i a t i o n i n d e g r e e o f s e tt in g c a u s e d

b y v a r i a t i o n i n t e n si o n .

8 . 4 . 2 S t e a m - s e t t i n g m e t h o d

S h o r t s t a p le p o l y e s t e r y a r n s i n c l u d i n g p o l y e s t e r / c o t t o n b l e n d s a r e n o r m a l l y s e t

b y r e l a x a t i o n i n s a t u r a te d s t e a m . T h e m o s t e f fe c t i v e m e a n s o f s ta b i l i si n g th e s e

m a t e r i a l s a re to s t e a m a t 1 0 7~ o n th e r in g s p i n n e r s tu b e a n d s o f t d y e i n g p a c k a g e s

u n d e r m i n i m u m t e n si o n . S t e a m i n g i s c a r ri e d o u t i n a n a u to c l a v e f it te d w i t h v a c u u m

p u m p , e .g . t w o t i m e s 1 5 r a i n a t 1 2 5 - 1 3 5 ~ w i t h i n t e r m e d i a t e e v a c u t i o n o r a l te r n a -

t i ve l y , fo r 60 r a i n w i t h s a t u r a t e d st e a m. S e w i ng t h r e a ds r e c e i ve s pe c i a l s e tt i ng

t r e a t m e n t s , d e s i g n e d t o c o n f e r s t a b i l it y w h i l s t p r e s e r v i n g t h e i r h i g h t e n s il e p r o p e r -t ie s . P o l y e s t e r g a r m e n t s , g a r m e n t l e n g t h s a n d h o s i e r y a re a ls o s t a b i li s e d b y s t e a m -

i n g in m u c h t h e s a m e w a y a s f or y a m s .



262 Heat-Sett ing

N ylon can be set in saturated s team at tem peratures above 1OO°C in an auto cla ve

by batchwise p rocess . Nylon ya m is wound on to a col laps ible paper tube or cross -w oun d in cheese form to a spring core and is treated in s team for 30 min cyc les ,

vacu um /s team 5 to 201bl in2/vacuum and rewoun d on to the spr ing in the case of

paper tub e. For textured nylon ya m s imilar packages can be used but the package

density is very m uch low er. W oven or warp knitted nylon fabrics are batche d in

open-w idth on to a per forated rol ler and set t ing cycle comm ences by a vacuum

exha ustion do w n to a pressure of 28 inches of Hg . Saturated s team is then injected

at the desired tem perature and treatm ent continued for 10 m in. Th is is followed by

a fur ther vacuum exhaus t ion and prolonged s teaming cycle of 20 min at se lected

tem perature. A f inal vacuum exhaustion com pletes the process . In the case of hose

and hal f -hose, the go ods are f ramed on to metal form ers on w hich the goods are

shrunk du ring s team ing operation. Typ ical s team sett ing condit ions are 115OC

(IOlbIin') to 130°C (25 lb / in2 ) for nylo n 6, 6 and 108OC (5 Ib/ in 2) to 121 °C

(15 lb/ in2) or nylon 6. Steam sett ing increases the build up of acid dyes and u nlevel

dy eing s w ill result i f the tem perature varies throughout the batch .

8 4 3Hydro-setting method

Th e hydro-sett ing or aqu eous heat-sett ing of polyester is don e with hot water in

a high tem perature l iquo r circulat ing machine at about 130°C. A typical cycle may

require 30 min. W ater (or s team ) prom ote sw el ling of fibre and may cause som e

hyd rolysis in the ester group s in polye ster chain. Th is causes part ial de struction of

intermo lecular bond s and depolymerisation of f ibre with a result in loss in tenacity.

How ever , the hydrosett ing temperature can be lowered by adding som e selected

organ ic or inorgan ic substances causing swell ing o f polye ster , but su ch condit ions

have n ot yet found industr ial application.

N ylon fabric can be hydro-set in hot w ater s ince the sw ell ing action assis ts in

w eake ning o r breaking intermo lecular bon ds. Th e fabric in f lat form is batched

onto a perforated m etal cylinder and im m ersed in hot or boil ing water for a short

period of t im e. Hy drosett ing at boil is roug hly equ ivalent to dry sett ing at 185OC.

T he texturised and tubular knitted fabrics are suitable as the fabric qu ali ty depend s

greatly on the metho ds of application. After set ting in boiling w ater polyester is

further shrunk by 11-12% on ex posure to hot air at 200°C. Unlike po lyester , nylonfabrics if set (relaxed) with bo il ing w ater shrinks only 3-4% on subse quen t expo-

sure to ho t air at 200°C.



He a t - S e t t ing 26 3

8 . 4 . 4 H e a t - s e t t i n g u s i n g t e n t e r f r a m e

S te n te r s a r e w ide ly use d f o r s t r e t c h ing , d r y ing , he a t - se t t i ng a nd f in i sh ing o f

f a b r i c s (F ig . 8 -3 ) . W ov e n a nd kn i t t e d f a b r ic s o f po lye s t e r a nd ny lo n f ib r e s and

F igur e 8 -3 . S te n te r f o r d ry ing , f in i sh ing a nd he a t - se t t ing k n i t t e d

a n d w o v e n f a b ri c s ( C o u r t e s y o f M o n t i s .p .A . ).

t he i r b l e nds a r e no r m a l ly he a t - se t on p in - s t e n te r i n ho t a ir . An a l t e rna t ive to the p ins t e n te r i s t he c l ip m a c h ine . The f a b ri c i s he ld in to the c ha ins e i the r by p ins m oun te d

in to a ba se p l a t e o r by c l ip s in wh ic h the f a b r i c e dge i s c l a m pe d be twe e n two

sm ooth su r f a c e s . S t e n te r s tha t a re u se d f o r s e t t ing on ly ha ve a li gh t p in c ha ins

whe r e a s s t e n te r s u se d f o r bo th d r y ing a nd se t t i ng ( f in i sh ing) a r e p r ov ide d wi th a

h e a v y c o m b i n e d p i n a n d c li p c h a in . F o r k n i t g o o d s v e rt i ca l l y r u n n i n g p i n s t en t e r

c ha ins a r e pa r t i c u la r ly su i t a b le . I n o r de r to be su i t a b le f o r d r y ing a nd se t t i ng pu r -

pose s , t he s t e n te r r a i ls a r e d iv ide d in to th r e e se c t ions a nd c a n be m ov e d l a t e r a lly

a bou t the c e n t r e li ne . The e n t r y se c t ion c ons i s t s f e e d ing in , w i th pa d d ing m a ng le ,

se lve dge unc ur l e r ( f o r kn i t t e d goods ) , sh r inka ge a ppa r a tus ( up to 30 %) , s e lve dge

f e e le r fo r a u tom a t i c c o r r e c t ion o f w id th a nd in s t r um e n t pa ne l w i th a ll sw i t c he s .

Th i s s e c t ion i s u sua l ly a bou t 5 m long f o r w ove n f a b r i cs a nd 7 m f o r w a r p kn i ts .

The c e n t r e s e c t ion i s as long a s ove n , wh ic h m a y ha ve f r om 3 to 8 he a t ing c ha m be r s

( se c t ions ) , e a c h a bou t 3 m long . The r e shou ld be at l e a s t two se t t ing f ie ld s . The

de l ive r y se c t ion i s a bou t 4 -5 m long to pe r m i t su f f i c i e n t c oo l ing to ta ke p l a c e be -

f o r e the f a b r i c is s t r ippe d o f f t he p ins by a r o l le r a nd e i the r r o l l e d o r p l a i te d . Onsom e m a c h ine s a n a i r b lowe r i s f i t t e d a f t e r t he he a t ing se c t ions to f o r c e c oo l a i r



2 64 Hea t - Se t t i n g

onto the f abr ic . The s ten ter f r ame i s usua l ly 80-100 fee t long and 70-100 inches

w id e . T h e s p eed r an g es f r o m 1 0- 45 m / m in w i th a m ax im u m s e t ti n g t im e in t h e

s e t t i n g zo n e 3 0 s ec at t em p er a tu r e r an g in g f r o m 1 75 to 2 5 0~ d ep en d in g u p o n th e

th i ck n es s an d t y p e o f t h e m a te r i a l.

T h e s t en t e r ch am b er s s h o u ld b e t h o r o u g h ly i n s u l a t ed f r o m a l l s i d es an d r e s t

f r ee ly o n p ed es t a l s . T h e ch o i ce o f h ea t i n g s y s t em u s ed - d i r ec t g as , i n d i rec t s t eam o r

o i l h ea t i n g o r e lec t r ica l h ea t i n g - d ep e n d s o n th e cu s to m er ' s req u i r em en t s . S in ce a i r

i s the t r anspo r t me dium for hea t , thus as the a i r ve loc i ty de creases , ava i lab le ene rgy

in t h e f o r m o f h ea t a l s o d ec reas es . D i f f e r en t s y s t em s , n am e ly P u f f e r , Kr an t z , J e t

e tc . a re used fo r c i r cu la t ing a i r a rou nd the c lo th . In conv en t ion al a i r f low sys tem s ,

f r e s h a i r i s f ed s ep e r a t e ly t o each co m p ar tm en t i n a s t en t e r , an d t h e ex h au s t i s

s im i l a r l y ex t rac t ed s ep e r a t e ly f r o m each co m p ar tm en t . T h e d em an d f o r m u l t i l ay e r

s t en t e r (F ig . 8 - 4 ) is in c r eas in g . By c o m b in in g a m u l t i - lay e r s t en t e r w i th th e co n -

F i g u r e 8 - 4. M u l t i- l a y e r s te n t e r in g m a c h i n e ( C o u r t e sy o f B r u c k n e r G m b H ) .

v en t io n a l en t r y an d ex i t o f s i n g l e - l ay e r s t en t e r i t i s p o s s ib l e t o o b t a in o p e r a t i n g

f l ex ib i l it y . T h e m a in ad v an t ag es a r e th e av o id an ce o f l o n g i tu d in a l d i s t o rt i o n s an d

th e ea s e o f o p e r a t i o n an d m a in t en an ce w i th t h is g ro u n d l ev e l a r r an g em en t . T h e

m ul t i - lay er s ten ter i s ava i lab le in ver s ions w i th 3 o r 5 f abr ic passe s ( layer s ) .

T h e s h r in k ag e i n l en g th an d w id th m ay b e a s m u ch a s 1 0% an d th i s m u s t b e

t ak en i n to co n s id e r a t i o n i n d e t e r m in in g t h e o v e r f eed an d t h e ad ju s tm en t o f t h e

w i d t h . M o s t o f t he s te n t er s m a k e p r o v is i o n f o r o v e r f e e d s - 5 % t o + 4 0 % . I f t h een t ry ro l le r s f eed the c lo th a t a s lowe r speed , the c lo th wi l l be ac tua l ly pu l led by the




t r a ve l l ing c ha ins , t hus ga in in g in l e ng th , bu t m a y c o r r e sp ond ing ly lo se the w id th .

Thu s , s l i gh t ly unde r f a b r i c c a n be r e du c e d to the r e qu i r e d wid th by ha v ing po s i t ivespe e d d i f f e r e nc e a nd s l igh t ly na r r o w e r f a b r i c c a n be b r ou gh t to i ts r e qu i r e d wid th

by l e s se n in g the spe e d d i ff e r e nc e a nd inc r e a s ing the w id thw ise pu l l ing a c tion . The

e x te n t t o wh ic h ove r f e e d ing c a n be e f f e c t e d de pe nds on f a b r i c t e x tu r e , c ons t r uc -

t ion , we a ve , f ib r e c om pone n t , c lo se r o r b r oa d c oa r se s a nd wa le s in kn i t goods .

P o l y e s t e r k n i t g o o d s s h o u l d n o t b e s t re t c h e d m o r e t h a n 5 % w i d e r t h a n t h e d e s i re d

e n d w i d t h . A n o v e r f e e d o f u p t o 2 0% ( g e n e ra l ly 6 - 1 0 % ) is c o m m o n l y u s e d i n k n i t

goods o r t e x tu r i s e d f a b r i c s in o r de r to l e ve l ou t va r i a t ions in t e ns ions c a use d by

kn i t t i ng . Fo r wov e n goo ds a n ove r f e e d o f 5 to 7 % is ge ne r a l ly su f f ic i e n t . The

o v e r f e e d d e v i c e m e c h a n i s m v a r i es f ro m m a k e to m a k e o f s t e n t e r . S o m e h a v e e l ec -

t r ic a l de v ic e ( e.g . Ar tos ) wh e r e a s o the r s m a ke use o f m e c ha n ic a l de v ic e ( e .g .

Pr im atex ) . I t i s a l so po ss ib le to ad ju s t d i f fe rent ia l ove r feed for r ight and le f t se l -

ve d ge s to c o r r e c t d i s to r tions .

Kn i t t e d f a b r i c f in i sh ing s t il l ha s c o ns ide r a b le r a t iona l i s a t ion , r e se r ve s to o f f e r

e spe c ia l ly in the f ie ld s o f p r oc e ss a nd r e c ipe op t im isa t ion . The p r inc ipa l p r oc e s s -

ing p r ob le m s a r e ina de qua te e l im ina t ion o f wa sh sh r inkage ; the phe nom e na o f ske wa n d b o w d i s to r ti o n ; a n d t h e p o o r r e p r o d u c i b il i ty a n d f r e q u e n t i m p a i r m e n t o f t h e

look o f the f a b r ic . I t i s e s se n t i a l to wo r k a t t he lowe s t poss ib l e t e ns ion a nd wi th

shor t, contac t -guide d fabr ic pa ths wi th ve r t ica l cha in re turn . Th is mainta ins a smal le r

ga p be tw e e n the u ppe r t r a c tion r o l le r a nd p inn ing de v ic e tha n wi th ho r i z on ta l c ha in

r e tu r n . The ve r t i c a l t r a nspor t c ha in , de s igne d f o r spe e ds o f up to 140 m /m in , c a n

c on t inuous ly m a in ta in the p r oduc t ion spe e ds r e qu i r e d in kn i t t e d f a b r i c f in i sh ing .

An e a sy r unn ing c om pe ns a to r , de v e lope d spe c ia l ly f o r kn i t t e d f a b r ic f in i sh ing , a l-

l o w s f o r s p e e d r e g u l a t io n w i t h e x t r e m e l y l o w f a b r ic t e n s io n s b y c o m p a r i s o n w i th

c on ve n t ion a l da nc ing r o l l e r c om bina t ions . F r om the t r a c t ion r o ll e r , t he kn i t t e d

f a b r i c i s f e d v i a a ve r y sho r t t r a nspor t pa th to the ove r f e e d un i t w i th spe c ia l ly

de ve lope d b r ush be l t s , wh ic h p r e s s the e dge s o f the kn i t te d f a b r i c in to the p in p l a t e s

w i t h u n i f o r m " g a t h e r ' ', e v e n a t r a te s o f 5 0 % . W h e n f e e d in g d r y f a b r ic i t is a d v is -

a b le to in se r t a s t e a m e r us ing sa tu r a t e d s t e a m in the e n t r y se c t ion f o r un i f o r m ho-

m o g e n e o u s m o i s t u r e d is t ri b u t io n . W i d t h w i s e c o n t r a c ti o n o f u p to 5 0 % c a n b e

s m o o t h l y e x t e n d e d w i t h o u t a n y fe a r o f c e n t re a n d s e l v e d g e b r e a k a g e . P r o d u c t i o nspe e d c a n be c ons id e r a b ly b oos te d by the use o f in f r a - r e d r a d ia to r s ( d r ye r ) be f o r e



26 6 He a t - S e t t ing

d r y i n g . T h e C o n v e y - A i r n o z z l e s y s t e m p r o d u c e s a s p e ci a l su p p o r t i n g e ff e c t a n d

e n s u r e s a b s o l u t e l y u n i fo r m " f l o a t i n g " o f t h e fa b ri c, p e r m i t t in g p e r m a n e n t r a p i dr e l a xa t ion o f the fa b r i c be f o r e the se tt i ng p r oc e ss p r ope r . M e thod s o f suppor t ing

kn i t t e d s t r uc tu r e s du r ing s t e n te r ing inc lude the use o f a i r c ush ions , e n d le s s be l t o r

o the r supp or t s [6 - 9 ]. S t e n te r s c ons id e r e d to be pa r t i c u la r ly su i t a b le f o r the p ro -

c e s s ing o f kn i t t e d f a b ri c s ha ve be e n de sc r ibe d [ 10- 13 ] . The y inc lude d r um s t e n te r s

[ 14] a nd s t e n te r s c a pa b le o f p r oc e ss ing f a b r ic in e i the r ope n - wid th o r tubu la r f o r m

[15 ] . He a t - se t t i ng c a l e nde r s m a y a l so be use d f o r the tr e a tm e n t o f t ubu la r f a b r i c

[16].

M a n y i m p o r t a n t a d v a n c e s h a v e b e e n m a d e i n t h e d es i g n o f c o n t ro l e q u i p m e n t

f o r s t e n te r s inc lude m e thod s o f m e a su r ing we igh t pe r un i t a r e a [ 17 ,18 ] , m o i s tu r e

c on te n t [ 19] a nd f a b ri c t e m p e r a tu r e [20 ] . The r e c om m e nd e d m e thod f o r c he c k in g

the t e m pe r a tu r e i s t o s e c u re the r m o e le m e n t s o r the r m opa p e r s to p i e c e go ods pa s s -

i n g th r o u g h t h e s te n te r . I m p r o v e m e n t s h a v e a l so b e e n m a d e i n m e t h o d s o f fe e d i n g

fabr ic to the s ten te r [21 , 22] .

8 . 4 . 5 S e l e c t i v e i n f r a - r e d e m i t t e r s m e t h o d

Poly e s t e r c a n be he a t - se t by e x pos in g the m a te r i a l unde r s e l e c t e d a re a s o f m a g-n e t i c s p e c t r u m o f in f r a -r e d ra y s . T h e w a v e l e n g t h o f th e ra d i a t io n s o u r ce m u s t b e

c ho se n w i th r e spe c t t o the a bso r p t ion ba n d o f the f ib r e i.e . a pa r t i c u la r i n f r a - r e d

w a ve le ng th i s c hose n f o r a pa r t i c u la r f ib r e. Fo r e xa m ple , i n the c a se o f po lye s t e r

the se l e c t ive in f r a - re d r a d ia t ion w a ve le n g th i s the r e g ion o f 1 to 4 g . The r a d ia t ions

o f wa v e le n g th o f 1 to 2 g pa s se s f r e e ly th r ou gh the po lye s t e r f a b r ic a nd tha t o f 3 to

3 .5 g a r e p r a c t ic a l ly c om ple te ly a bso r be d by po lye s t e r . B e c a u se o f th i s abso r p t ion ,

i t c a n be a s sum e d tha t t he e ne r g y i s g ive n up to the in t e r io r f ib re s t ruc tu r e , wh i l e

e m is s ions be low th i s r a nge a r e d i s s ipa te d e lse whe r e . S uc h r a d ia t ion sou r c e s a nd

f i lt e r s w h ic h c lose ly a ppr oa c h the r e qu i r e m e n t s , a r e now de ve lope d a nd a r e c a l l e d

" se l e c t ive e m i t t e r s ' ' . The a bso r be d e ne r gy i s r e d i s t r ibu te d wi th in the s tr uc tu r e o f

the f ib r e , H- bonds a nd Va n de r Wa a l s ' f o r c e s b ind ing the m ole c u le s toge the r a r e

d i s r up te d a n d the se d i s r up te d m ole c u le s a r e a t l ibe r ty to r e a r ra nge the m e se lve s in to

pos i t ions o f lowe s t e ne r g y ( l e a s t s tr e s s) .

Se t t ing machin es w i th inf ra - red se lec tive emi t te r s a re des igned in a m ann er wh ich

pe r m i t s i n f r a - r e d w a ve s to be ge ne r a t e d a t t e m p e r a tu r e s in the 10 0 + 20~ r a nge .The m a c h ine a l low s c on t inuo us p r oc e ss ing a nd c ons i s t s o f a n e n t ry s t a nd , a s e t t ing

c ha m be r w i th ve r t i c a l r ows o f in f r a - r e d bu r ne r s , a n a d ja c e n t c oo l ing z one a nd a




de l ive r y de v ic e . The d i s t a nc e o f the bu r ne r s f r om the fa b r i c c a n be a d jus t e d . One

s u c h m a c h i n e i s P o l y f i x m a c h i n e ( T i m e x , F r an c e ) a n d c a n o p e r a te a t s p e e d s f r o m15 to 50 m /m in a nd i s a va i l a b le in d if f e r e n t wo r k ing w id ths . As a ru l e the se m a -

c h ine s do no t c on t ro l wa r p a nd f i ll i ng t e ns ions . Ho we ve r , t he se de v ic e s c a n be

u s e d w i t h i n t e n t e r h o u s i n g s a n d n e c e s s a r y c o n t r o l s c a n b e d o n e i n d i c a t e d u n d e r

t e n te r f r a m e .

8 .5 H e a t - s e t t in g C o n d i t i o n s f o r D i f fe r e n t K i n d s o f F i b r e s

The r e a r e va r ious k inds o f syn the t i c f ib r e s s t r uc tu r a l ly w i th d i f f e r e n t m e l t ing

po in t s a nd w i th d i f fe r e n t he a t - se t t ing c ond i t ions . Ev e n a s l igh te s t va r i a t ions in

he a t - se t t i ng c ond i t ions , na m e ly t e m pe r a tu r e , t im e a nd t e ns ion in f lue nc e the se tt i ng

e f f ec t , r e ga r d le s s o f the sy s t e m use d .

8 . 5 . 1 P o l y e s t e r f a b r i c s

Polye s t e r p i e c e goods a r e p r e - se t w i th ho t a i r on p in s t e n te r s f o r 20 - 40 se c a t

18 0 -210 ~ a c c o r d ing to the type , de ns i ty a nd we igh t o f t he m a te r i a l, w i th m in i -

m um te ns ion o n the goods to c on t r o l t he d ry he a t s t a b i li t y to l e s s tha n the a c c e p te d

1% sh r inka ge [23 ]. He a v ie r f a b r i c s li ke su i tings re qu i r e m or e t im e a s f a b r ic he a t -

ing t im e i s m o r e . P la in f a b r ic s , w ove n f r om unse t ya m s m a y be e xpe c te d to sh r inkb y a p p r o x i m a t e l y 5 % i n w a r p a n d w e f t d u ri n g s c o u r i n g p r o c e s s a n d t h e i r r e s id u a l

p o t e n t i a l s h r in k a g e r a n g e f ro m 4 . 5 % t o a b o u t 1 1 % o v e r th e t e m p e r a t u r e r a n g e o f

150 to 220~ S taple f ibre fabr ics shr ink le ss than f i lam ent fabr ics and s tab i l ity

a de q ua te f o r a ppa r e l f a b r ic s i s c on f e r r e d by se tt i ng a t 17 0 to 18 0 ~ Po lye s t e r

fabr ics a re e f fec t iv e ly d im ens ion a l ly s tab le i f i t i s se t a t a tem pera ture of 30 to 40~

h igh e r tha n the t e m pe r a tu r e to wh ic h the f ib r e is sub je c t e d to e xpo se du r ing subse -

que n t p r oc e sse s .

8 . 5 . 2 N y l o n f a b r i c s

The se t t ing c ond i t ions use d f o r d i f f e re n t ny lon f a b r i c s va r y de pe nd in g up on the

m e l t ing po in t o f ny lons , he a t - se t ti ng m e thods , r a t e o f t ra ns f e r o f he a t a n d the w e igh t

o f the c lo th be ing p r oc e ss e d . Fo r p r a c t i c a l pu r pose s , t he c ond i t ions o f ho t a i r

s e t t i ng be ing use d f o r d i f f e r e n t ny lons a r e shown in Ta b le 8 .1 . An ove r f e e d o f

2 - 3 % i s n o r m a l l y r e q u i r e d b u t th i s h a s t o b e d e t e r m i n e d b e f o r e - h a n d d e p e n d i n g

upo n the ha nd le a nd s t r uc tu r e r e qu i r e d .

O n s t e a m i n j e ct i o n s t e n te r s th e h e a t i n g m e d i u m is a m i x t u r e o f s u p e r - h e a t e ds t e a m a nd a ir . The su pe r he a te d s t e a m r e qu i r e d f o r the pu r p ose c a n be ge ne r a t e d

ins ide the c h a m be r by in j e c t ion o f sa tu r a te d s t e a m . I n th is m ix tu r e to t a l he a t c a pa c -



2 68 Hea t - Se t t i n g

T A B L E 8 . 1

Hea t - s e t t i n g Co n d i t i o n s f o r Di f f e r en t N y lo n sT y p e o f n y l o n T i m e o f c o n t a c t ( se c ) T e m p e r a t u re o f s e tt in g ( ~

N y lo n 6 1 5 - 20 1 90-1 93

N y lo n 6 , 6 1 5 - 2 0 2 00- 2 3 0

N ylo n 11 15-20 = 150

Q u in a 1 5 - 2 0 1 90

i ty o f t h e m e d iu m i s i n c r eas ed co n s id e r ab ly b e cau s e t h e s p ec if i c h ea t o f s team - a i r

m ix tu r e i s a lm o s t tw ice t h e a i r a lo n e an d t h e f ab ri c can b e s e t a t a r u n n in g s p eed o f60 - 70 y d s / m in . W ar p k n i t t ed an d l i g h t w o v en f ab r i c s r eq u i r e o n ly 3 - 4 s ec co m -

p a r ed t o 1 5 - 2 0 s ec w i th h o t a i r a lo n e . Ap ar t f r o m th i s , s t eam - a i r m ix tu r e a l s o

s cav an g e t h e a i r f r o m th e s e t t i n g ch am b er an d t h u s r ed u ce t h e o x id a t i o n d eg r ad a -

t i o n an d m in im i s e s t if f en in g an d y e l l o w in g o f n y lo n s . Ho w ev er , th i s s y s t em re -

q u i r e s a h ig h ly e f f i c i en t i n s u la t i o n o f t h e h ea t - s e t t i n g ch am b er t o m in im i s e co r r o -

sion.

8 . 5 . 3 T e x t u r i s e d p o l y e s t e r a n d n y l o n f a b r i c s

T h e ch o i ce o f s e t ti n g co n d i t i o n s f o r b u lk ed y am m a te r i a ls d ep en d s o n t h e t y p e

o f b u l k i n g p r o c e s s t h a t h a v e b e e n e m p l o y e d . I n g en e r a l, h i g h te n s i o n m u s t b e

av o id ed d u r in g h ea t - s e t t in g p r o ce s s , b ecau s e o f d an g e r o f p u l l i n g o u t th e b u lk in g

effect .

W o v e n f a b r i c s m a d e f r o m t e x t u r i s e d p o l y e s t e r y a m s s h o u l d b e h e a t - s e t f o r

2 0 - 3 0 s ec a t1 60~ w i th s li g h t w id th ex t en s io n t o r em o v e c r eas es , b u t w i th o u t t ru e

o v e r f ee d s o a s t o av o id th e p r o d u c t io n o f r i p p l ed s e lv ed g es . H ig h e r s e t ti n g tem -

p e r a tu r e s ( e . g . 1 65- 1 70~ m ay b e r eq u i r ed to co n t r o l t h e t en d en cy o f s o m e f ab r ic s

o f ti g h t e r co n s t r u c t i o n t o c r eas e d u r in g j e t d y e in g , b u t t h e s e t em p er a tu r e s can cau s e

s o m e lo s s o f y a r n b u lk an d ten d t o g iv e a m o d i f i ed , l ean e r h an d le . Kn i t t ed g o o d s

a r e co m p o s e d a lm o s t ex c lu s iv e ly o f t ex tu r ed y am s . P o ly es t e r d o u b le - j e rs y f ab r ic s ,

w e f t k n i t ted f r o m s t ab i li s ed b u lk ed f i l am e n t y am s m ay b e h ea t - se t o n a s t en t e r fo r

3 0 s ec a t 1 50~ T h e g o o d s s h o u ld n o t b e s tr e t ch ed m o r e th an 5 % w id e r t h an t h e

d es i r ed en d w id th . An o v e r f eed o f u p to 2 0% can b e g iv en f o r k n i t t ed g o o d s .

F o r t ex tu r i s ed n y lo n , a f t e r r e l ax in g h ea t - s e t ti n g i s n o r m a l ly d o n e a t 1 5 0 - 1 60~f o r 30 s ec i n a h o t a i r s t en t e r w i th an o v e r f eed o f 1 0 - 1 5 %. T h e o v e r f eed can b e

in c r eas ed t o 1 5 - 2 0% d ep en d in g u p o n th e ty p e o f st re t ch . T h e h ea t - s e t t in g t em p er a -



Hea t - Se t t i n g 2 69

tu r e i s a lw ay s k ep t b e lo w th e tem p er a tu r e o f t ex tu r is a t i o n . N y lo n can b e h ea t - s e t

o n ly o n c e [2 5 , 2 5 ] an d d i f fe r s i n t h is r e s p ec t f r o m p o ly es t e r f i b r e s , w h ich can b er ep ea t ed ly h ea t - s e t a t p r o g r e s s iv e ly h ig h e r t em p er a tu r e s . T h i s i s o f p a r t i cu l a r im -

p o r t an c e i n t h e p r o ce s s in g o f k n i t t ed f ab r i c s p r o d u ced f r o m t ex tu r ed y a r n s s i n ce

s u ch y a m s h av e a l r ead y b een p e r m an e n t ly h ea t -s e t . F o r an y k n i t t ed s t r u c tu r e a

m in im u m en e r g y s t a t e ex i s t s an d i f a k n i t t ed s t r u c tu r e i s a l l o w ed to r e l ax a f t e r

s t r e tch ing , it r e tu rn s to the equ i l ib r ium con di t ion [26] . S ince the se t t ing ef fec t

o b t a in ed w i th f ab r i c s k n i t t ed f r o m t ex tu r ed n y lo n i s e s s en t i a l l y t em p o r a r y , i d ea l ly

the f abr ics a re se t und er r e laxed c ond i t ions . I t i s no t a lwa ys poss ib le to do th i s .

H o w e v e r , t h e f a b r ic s m a y b e s e t w i t h i n 5 - 1 0 % o f r e l a x e d d i m e n s i o n s w h i c h w i ll

no rm al ly sh r ink less than 5% [27] . Al te rna t ive ly , hea t - se t t ing in kn i t ted f abr ics can

b e b r o u g h t a b o u t b y p r e v e n t i n g t h e c h a n g e s i n l e n g th o f y a m i n e a ch l o o p a n d i n

th e s h ap e , cu r v a tu r e o r d eg r ee o f i n t e r m e s h in g o f t h e lo o p s [2 8] .

8 . 5 . 4 A c r y l i c a n d m o d a c r y l i c f a b r i c s

T h es e f i b r e s can n o t b e h ea t - s e t i n t h e co n v en t io n a l s en s e s i n ce t h e f i b r e s a r e

r ead i ly s tr e t ch ed o r d e f o r m ed a t t em p er a tu r e s ab o v e 75 ~ T h e d eg r ee o f s t ab il it y ,

h o w ev e r , can b e o b t a in ed b y p as s in g t h es e f ab r i c s th r o u g h a h o t a i r s t en t e r a t ab o u t1 2 0~ T e m p er a tu r e s ab o v e 1 2 0~ m ay cau s e d i s co lo u r a t i o n o f t h e f ab r ic s . F o r

b l en d ed f ab r i c s co n t a in in g ac r y l i c an d m o d ac r y l i c f i b r e s h ig h e r h ea t - s e t t i n g t em -

p e r a tu r e s m ay b e r eq u i red . Kn i t t ed f ab r i cs p r o d u ced f r o m a f eed e r b l en d o f ac r y li c

and tex tu re d po lye s ter f ib res , a r e hea t - se t a t abou t 160~ fo r 30 sec .

8 . 5 . 5 C a t i o n i c d y e a b l e p o l y e s t e r f i b r e f a b r i c s

Cat io n i c d y eab l e p o ly es t e r (C DP E T ) an d r eg u l a r p o ly es t e r f i b r e s d i f fe r m u ch in

ch em ica l p r o p e r t i e s . Gen e r a l l y , CDP E T h as a s l i g h tl y l o w e r h ea t r e s i s t an ce t h an

th e r eg u l a r P E T , s o th a t h ea t - s e t ti n g t em p er a tu r e f o r C DP E T i s k ep t s l i g h t l y l o w er

th an th a t o f n o r m a l P E T . T ab l e 8 .2 s h o w s th e ap p r o x im a te h ea t - s e t t i n g co n d i t i o n s

o f d i f f e r en t p o ly e s t e r f i b re s .

8 . 5 . 6 T r i a c e t a t e f i b r e s

An im p o r t an t p r o p e r ty o f t r iace t a t e f i b re s i s t h e ab i li t y to u n d e r g o s t r u c tu r a l

ch an g es u n d e r t h e i n f lu en ce o f h ea t . T r i ace t a t e i s n o t e f f ec t ed b y d r y h ea t u p to

1 5 0~ T h e fi b r e b ec o m es i n c r eas in g ly p l a s t i c b e tw een 1 5 0 to 1 90~ an d a t s ti ll

h ig h e r t em p er a tu r e s u p t o 2 2 0~ m o lecu l a r r eo r i en t a t i o n o ccu r s t o an i n c r eas in gex t en t a cco m p an ied b y i n c r eas e i n c r y s t a l l in i t y s o t h a t im b ib a t i o n o f th e f i b r e f a ll s

f r o m 1 6 to 1 0% an d th e r e is co r r e s p o n d in g r ed u c t io n i n ab s o r p t i o n an d d es o r p t i o n



270 Heat -Se t t ing

TABLE 8 .2 .

Ap p r o x im a te Hea t - se tt i n g C o n d i t io n s o f D i f fe r en t P o ly es te r sTy p e o f P o ly es te r Heat - se t t ing Temp. (~ Co ntac t t ime ( sec)

100% Polyes te r (normal)

C D P E T

Car r i e r - fr ee d y eab le P E T

(a) Po lybu ty lene te reph tha la te ,

T y p e - 1

(b) D icarboxy l ic ac id , Typ e-2( c) Co p o ly m er , Ty p e - 3

180-220 20-40

170-180 20.40

160-180 30

170-190 30190-200 30

of dyes . A perm anen t change in therm oplas t ic behav iour takes p lace and the f ib re

bec om es inc reas ing ly less p las t ic . Tab le 8 .3 show s the ex ten t ion f igures o f t r iac -

TABLE 8 .3 .

Th e r m o p la s t i c Beh av io u r o f T r i ace ta t e F ib r e s

Tempera tu re(oc) % Exten t ion(under load o f 0 .02 g /den)

No rma l t r iace ta te Tr iace ta te a f te r t rea tment

at 200~ for 5 m in

20 0.10 0.10

140 0.10 0.10

160 0.15 0.10

165 0.40 0.10

175 1.10 0.20

185 3.00 0.70

190 8.00 1.00

e ta te f ib res . S im i la r resu l t s can be ob ta ined i f t r iace ta te is exposed to comb ined

ef fec t o f hea t and mois tu re a t tem pera tu res lowe r by 60-70~ than when dry hea t i s

used on ly .

8 . 5 . 7 P o l y v i n y l c h l o r i d e f i b r e s

The ou ts tand ing p roper ty o f these f ib res is the shr inkage on hea t ing w hich en-

ab les the manu fac ture o f var ious spe c ia l ty p roducts . The fabr ic can be hea t - se t by



Heat -Set t ing 271

p as s in g i t t h r o u g h a h o t a ir st en t e r w i th n eces s a r y o v e r f eed . N o r m a l f eed in g , w h ich

g iv es s h r in k a g e i n th e w ef t d i r ec t io n , can b e d o n e i n o n e p as s ag e a t 95 ~ a t a s p eedd ep en d in g o n t h e f ab r ic co n s t r u c t i o n . Sh r in k a g e can a ls o b e a l l o w e d to tak e p lace

d u r in g o r a f t e r d y e in g . M a te r i a l s co n t a in in g f i b r e s w i th i n h e r en t s h r in k ag e s h o u ld

b e p r o c e s s e d a t t e m p e r a t u r e s n o t e x c e e d i n g 7 0~ P r e - s h r u n k f ab r ic c a n b e w e t

p r e - t r ea t ed a t 96 -1 00~

8 . 5 . 8 E l a s t o m e r i c f i b r e s

F ab r i c s co n t a in in g e l a s to m er i c f i b r e s can b e h ea t -s e t . A tr i co t o r s leek - k n i t

f ab r ic k n i t t ed f r o m n y lo n 6 an d p o ly u r e th an e m ay b e s a t i s f ac to r il y h ea t - s e t a t 1 80 -

1 85 ~ f o r 2 0 - 2 5 s ec. S l i g h t l y h ig h e r t em p er a tu r e s (1 90~ m ay b e u s ed f o r n y lo n

6 ,6 . Ho w e v er , t h e r eq u i r ed w id th an d s t r e t ch ch a r ac t e r is t i c s o f t h e f i n i sh ed f ab ri c

d e t e r m in e t h e p r ec i s e co n d i t i o n s t o b e em p lo y ed w i th a p a r t i cu l a r f ab r i c [ 2 9 ] .

8 .6 H e a t - s e t ti n g o f B l e n d e d F i b r e F a b r i c s

N e w f ib r e s a n d n e w e r b l e n d e d f a b ri c s h a v e b e e n p r o d u c e d a n d t h e s e a r e a ls o to

b e h ea t - s e t f o r s u cces s f u l d y e in g an d f i n i s h in g o p e r a t i o n s .

8 .6 .1 P o l y e s t e r / c o t t o n b l e n d s

Sh o r t s t ap l e p o ly es t e r f i b re s a r e o f t en b l en d e d w i th co t t o n o r s o m e o th e r ce l lu -los ic fib res . N orm al ly hea t - se t t ing in s ten ter wi th ho t a i r i s car r ied ou t a t 180~ fo r

3 0 secs . H ig h e r t em p er a tu r e s m ay d i s co lo u r th e ce l l u lo s i c p o r t i o n o f t h e m a te r ia l .

For incre ased s tab i l ity , se t t ing may be car r ied ou t even a t 200~ fo r 30 secs wi tho u t

s e r io u s r i s k o f d am ag in g t h e ce ll u lo se . T h e f ree w ef t - s h r in k ag e o f a t y p i ca l p o ly es -

te r / co t ton sh i r t ing f abr ic i s abou t 4% a t i t s normal se t t ing tempera tu re , bu t th i s i s

r e s t r i c t ed t o 2 - 3 % ( i. e. 1 - 2 % r e s id u a l s h r in k a g e i s a l lo w e d ) i n o r d e r t o en s u r e t h e

r em o v a l o f c r eas es an d t o g e t co n t r o l o v e r w ef t s t r a ig h tn es s .

8 . 6 . 2 P o l y e s t e r / w o o l b l e n d s

P o ly e s t e r / w o o l b l en d ed f ab r ic s a r e n o r m a l ly h ea t - s e t b e f o r e d y e in g . S im i l a r

e f f ec t i s o b t a in ed o n t h e w o o l co m p o n en t o n th e b l en d b y c rab b in g . P o ly es t e r /

w ool b l en de d f abr ics ca n be hea t - se t in a ho t a i r s ten ter fo r 30 secs a t 180 + 10~

F o r w o r s t e d - s p u n g o o d s 3 - 5 % r e l a x a t i o n s h r i n k a g e i s a l l o w e d b o t h w a r p a n d w e f t

an d f o r w o o l l en - s p u n m a te r i a l s 1 - 2 % is a l l o w ed . T h e w o o l s h o u ld b e a l l o w ed th e

n o r m a l m o i s tu r e reg a in b e f o r e h ea t - s e t t in g [3 0] . F o r b l en d s co n t a in in g m o r e th an

40% polyes ter con ten t , hea t - se t ting i s done w i th adequate over feed to avo id shr inkage

d u r i n g d y e i n g o p e r a t i o n s. T o p d y e d w o o l r i c h b le n d q u a l it ie s o f p o l y e s t e r /w o o l



27 2 H e a t -S e t t i ng

fa b r i c s ha v i ng w oo l c on t e n t a bove 6 7 % ne e d no t be he a t - s e t a s a de qua t e d i me n-

s i o n a l s t a b i l i t y c a n b e i m p a r t e d b y a u t o c l a v e d e c a t i s i n g p o p u l a r l y k n o w n a sK . D . F i n i s h . A f t e r s e tt ing , t he good s m a y be da m pe d o r s te a m e d t o r e s t o r e no rm a l

e qu i l i b r i um mo i s t u r e c on t e n t o f t he w oo l a s r a p i d l y a s pos s i b l e . The s e qu e nc e o f

ope ra t i ons i s s l i gh t ly d i f f e r e n t, a c c o rd i ng t o w he t h e r a c l e a r -c u t o r mi l l e d f i n i s h i s

r e qu i r e d ; f o r c l e a r - c u t f i n is he s , he a t - s e t t i ng m a y e i t he r p r e c e de o r fo l l ow d ye i ng .

For mi l l e d f i n i s h , i t i s r e c omme nde d t o c a r ry ou t he a t - s e t t i ng a f t e r mi l l i ng a nd

dye i ng . S i nge i ng s ho u l d fo l l ow he a t - s e tt i ng , un l e s s t he fa b r ic i s t o be mi l l e d , w he n

s i nge i ng p re c e de s he a t - s e tt i ng .

8 . 6 . 3 P o l y e s t e r / l i n e n b l e n d s

Pol y e s t e r / l ong- s t a p l e f i b re s a r e a ls o us e d i n t he li ne n i ndus t ry , w he re t he ya rns

m a y b e o f e i th e r th e ' s t r e tc h - b r o k e n ' o r ' u n b r o k e n ' t y p e, b u t ar e m o r e c o m m o n l y

of the l a tt e r . Hea t -se t t ing o f such fabr ics m ay be ca r r i ed out a t 180~ for 30 secs on

t he ho t a ir p i n s t e n t e r, a l l ow i ng up t o 2% w e f t s h r i nka ge w i t h ove r f e e d i ng on l y t o

c om pe n s a t e fo r a ny w a rp s h r i nk a ge t ha t ha s oc c u re d i n t he p r e v i ou s p roc e s s .

8 . 6 . 4 P o l y e s t e r / s i l k b l e n d s

H e a t - s e t t i ng o f po l ye s t e r /s i l k f i b r e s b l e nde d f a b r ic s c a n be c a r r i e d ou t on s t e n t e ra t 190 ~ fo r 30 se c s . The i n t roduc t i on o f up to 50 % po l ye s t e r doe s no t e f f e c t t he

c ha ra c t e r i s t i c s d r a pe a nd ha nd l e a s s oc i a t e d w i t h s il k fi b r es .

8 . 6 . 5 P o l y v i n y l c h l o r i d e / c e l l u l o s i c f i b r e s b l e n d s

For b l e nde d f a b r i c s w i t h c e l l u l os i c f i b r e s i t i s pos s i b l e t o p roduc e he a t - e m-

bos s e d b l e nd f a b r i c s w i t h 25% po l yv i ny l c h l o r i de f i b r e s. H e a t tr e a t m e n t i s c a r r i e d

ou t by one pa s s a g e on p i n - s t e n t e r w i t hou t ove r f e e d a t 8 5 -90 ~ a nd if f o r e xa m pl e

a 1 5 -17 % s h r i nka g e i s t o be a c h i e ve d , t he s pe e d o f t r a ve l is a bou t 10 m/ m i n .

8 .7 E f f e c t o f H e a t - s e t t i n g o n V a r i o u s P r o p e r t i es o f S y n t h e t ic F i b r e s

8 .7 .1 S t r u c t u r a l c h a n g e s o f p o l y e s t e r a n d n y l o n

Pol y e s t e r i s no t a f as t c rys t a l l is i ng po l yme r . The r a t e o f c rys ta l l i sa t i on i s ma x i -

m um fo r po l y e s t e r a t a round 180 ~ The m a x i m um c ry s t a l li s a t ion ra t e fo r po l ye s -

t e r is a bou t 0 . 0 16 / s e c , w h i l e i t i s 0 . 14 / s e c fo r ny l on 6 . The fo l l ow i ng c ha n ge s t a ke

p l a c e a s a func t i on o f i nc r e a s i ng t e m pe ra t u r e i n po l ye s t e r w h e n he a t - s e t unde r f r e e

to re lax condi t ions ( i . e . f ree annea l ing) and when he ld t au t a t cons tant l ength ( i . e .

t a u t a nne a l i ng ) :



Heat-Se t t ing 273

i) Cry s ta l l in i ty inc reases w i th inc reas in g tem pera tu re in both the cases , but i s

m o r e f o r fr e e o r s la c k a nne a le d sa m ple s a t a ll t e m pe r a tu r e s .i i) Cry s ta l s ize inc reases in both cases .

i ii ) C r ys t a l l i t e o r ie n ta t ion a nd b i re f r inge nc e inc r e a se in c a se o f t a u t a nne a le d

sa m ple s , b u t de c r e a se in c a se o f fr e e a nne a le d sa m ple s .

iv) Am orph ous or ienta t ion decreases in both the cases. In f ree annea led sample

the decrease i s grea te r due to shr inkage a l lowed.

v ) The num be r o f c r ys t a ls in the f ib r e inc r e a se s bu t at h ighe r t e m pe r a tu r e s ,

the c r ys t a ls f u se toge the r a nd the i r t o ta l num be r d e c r e a se s a nd c r ys t a l s be -

c om e pe r f e c t .

v i ) Am or ph ous v o lum e pe r c rys t a l s f i rs t de c r e a se s a nd the n inc re a se s in bo th

the cases.

v i i) The g la s s t r a ns i t ion t e m pe r a tu r e f i rs t i nc r e a se s a nd the n de c r e a se s w i th

inc reas ing hea t - se t t ing tempera ture .

v i ii ) I nc r e a s ing t e nde nc y f o r pha se se pe r a tion a t h igh he a t - se t t ing t e m pe r a tu r e s

is poss ib le .

Hea t - se t t ing processes resu l t in inner changes in the amine end gro up con tent ofny lon f ib re s a nd suc h c ha nge s w i l l on ly s l igh t ly m od i f y the up ta ke o f a c id dye s.

The de ns i ty a nd c r ys t a l l i n i ty o f ny lon inc r e a se on se t ti ng bo th in d r y he a t a nd in

sa tu r a te d s t e a m . App l i c a t ion o f t e ns ion a s s i s ts i n the de ve lopm e n t o f c r ys t a l l i n i ty .

W he n hea ted unde r tens ion or ienta t ion inc reases . The inc reased or ienta t ion i s los t,

howe ve r , by a l lowing the s t r e s s in the f ib r e s m a in ta ine d unde r t e ns ion to r e l a x .

Cry s ta l l in i ty and c rys ta l s ize inc rease mo re readi ly a t a low er tem pera tu re for s team

se t s a m p le c om pa r e d to d ry se t s a m ple s . The o r i e n ta t ion o f the c r ys ta l l i ne re g ions

r e su l t ing f r om bo th type s o f he a t - se tt i ng show s im i l a r t r end w he r e a s the o r i e n ta t ion

of a m o r phou s r e g ions o f the we t s e t m a te r i a l i nc r e a se r a p id ly w i th the se t t i ng t e m -

pera ture . Th e mod ulus of the f ibre inc reases on dry hea t - se t t ing and i t dec reases on

s t e a m he a t -se t t ing . I nc r e a se in m o du lus o c c u r s, i f he a te d unde r t ens ion . S h r inka ge

of the f ib r e de c r e a se s w i th he a t - se t t i ng t e m pe r a tu r e a nd i s r e l a t e d in a n inve r se

fashion to the c rys ta l l in i ty .

8 . 7 . 2 D i m e n s i o n a l s t a b i l i t y

The h igh er the tempera ture to whic h the ya rn or fabr ic is exposed , the h ighe r theresul tan t shr ink age over the tem pera tu re rang e of 100-200~ [31] . F igs . 8 -5 and



274 Heat -Set t ing

8-6 i l lustrate the free shrinkag e of a typical unset polyeste r ya m in hot, dry a ir and

15

d= = 1 0

. _ rI ,=

5

0

6 0 1 0 0 1 4 0 1 8 0 Z 2 0

A i r t e m p e r a t u r e , ~ C

10

, c _

. % '~ , : . t.~ , , l e m , ~ e r a l . . , r e . (

F i g u r e 8 - 6 . F r e e s h r i n k a g e o f

F ig ure 8 -5 . Free sh rink a ge o fp o ly e s ter p o ly e s t er f i l a m en t y a rn ( m ed ium

yarn (m ed ium tenacity) , in hot a ir. tenacity) , in saturated steam.

in sa tura ted s t eam resp ec t ive ly . As the result o f shr inkage , the m echan ica l proper-

t ies o f the f ibre cha nge so that i ts ex tens ib i l i ty increases and breaking load d imin-

i shes w i thout apprec iably chang in g the work o f rupture . F ig . 8 -7 show s the e f fec t

0 .8

.l..,a

r

0.4

(D.4,..a

>

0 1

( i )

. o , , / . . . ( ii ) \ " ~

- - . . / / ~ . ~ " ......... ... 9 . . . , . . . . \

. . . . . \ , . " ' kf . , /" /, ....

I I L i L

60 100 140 180 2 20

Heat-set t ing temperature (~

Figure 8-7. Tension produced in heat-setting at constant len gth. [(i) unset yarn, producer

twist, 30 t.p.m.; (ii) unset, thrown, 300 t.p.m.; (iii) steam-set, thrown 300 t.p.m.].



Hea t - Se t t i n g 2 75

o f t en s io n p r o d u ce d i n p o ly e s t e r y a r n o n h ea t - s e t t i n g a t d i f f e ren t t em p er a tu r e s . In

g en e r a l , t h e t en s io n i n t h e y am a t fi rs t in c r eas es b u t t em p er a tu r e s o v e r ab o u t 1 80~

i t d ec r eas es s t eep ly . T h e t h i r d cu r v e ( i i i) o f F ig . 8 -7 rep r e s en t s t h e t en s io n p r o -

d u ce d i n a p o ly e s t e r y am th a t h av e b een tw i s t s e t i n s t eam a t 1 1 0~ an d t h e t en s io n

i s u n l i k e ly t o ex ceed 0 .1 g / d ec i t ex u n l e s s t h e y am i s d e l i b e r a t e ly s t r e t ch ed [3 2 ].

In g en e r a l , t h e h ig h e r t h e s e t t i n g t em p er a tu r e , t h e l o w er i s th e r e s u l t an t s h r in k -

ag e o f t h e h ea t - s e t f ab ri c a t an y g iv en t em p er a tu r e . T h e s h r in k ag e o f u n s e t p o ly es -

te r f abr ic a t 175~ i s abo u t 15% as co m pa red to 1% for the sam e fabr ic se t a t

2 2 0~ F ab r i c s co n t a in in g b o th d y ed y a r n s an d u n s e t y a m t en d t o s h o w d if f e ren t i a l

s h r in k ag e e f f ec ts , an d t h es e m u s t b e s e t a t t h e h ig h es t t em p er a tu r e p e r m i t t ed b y t h e

s u b l i m a t i o n f a s m e s s o f t h e d y e d y a m s .

8 . 7 . 3 S t i f f n e s s

T h e s e t t in g p r o ces s s t if f en s th e f ab r ic , w h ich i s u n d es i r ab l e . H ig h e r t h e s e t ti n g

t em p er a tu r e , m o r e i s t h e s t if f en in g . A f a ir l y l i n ea r co r r e l a t i o n ex i s t s b e tw een th e

s t i ff n es s an d s e t t i n g t em p er a tu r e [ 3 1 ]. T h e s t i f f en in g is d u e to th e f o r m a t io n o f

co n t in u o u s f i lm o n t h e f i b r e s u r f ace an d h ig h t en s io n d ev e lo p ed d u r in g s e t t i n g .

T h e s t i ff en in g e f f ec t is lo s t i f t h e f ab r ic i s s u b s eq u e n t ly t r ea t ed m ech an ica l l y e . g.b y d y e in g o n a w in ch . H ig h t en s io n s d u r in g s e t t in g l ead s to th e p r o d u c t io n o f a t h in

p ap e r l i k e an d im p o v e r i s h ed h an d le w h i l e f r ee r e l ax a t i o n g iv es a s o f t an d s i l k y

f ab ri c . Ho w e v er , i t i s d i f f icu l t to co m p le t e ly e l im in a t e t en s io n s an d f u ll re l ax a t i o n

a l s o l ead s t o co n s id e r ab l e l o s s o f y i e ld . A l s o , t en s io n s h av e t h e e f f ec t o f r em o v in g

y a r n c r im p . Ab o u t 3 - 4 % p o ten t i a l y a r n s h r in k ag e i s r e s t r a in ed an d th e re s t is a l-

lowed to f r ee ly shr ink in the s ten ter .

8 .7 .4 C r e a s e r e c o v e r y

On e o f t h e p u r p o s e o f h ea t - s e t t i n g i s t o r ed u ce t h e ex t en t o f c r eas in g o n s u b s e -

q u en t d y e in g an d w as h in g p r o ces s es . T h e h ig h e r t h e s e tt i n g t em p er a tu r e t h e l e s s i s

t h e w e t c r eas in g . T h e d e g r ee o f w e t c r eas in g , is h o w ev e r a l s o r e l a t ed t o f ab r ic

co n s t r u c t i o n , f o r ex am p le , o p en o r l o o s e co n s t r u c t i o n f ab r i c s s h o w b e t t e r c r eas e

r eco v e r y t h an d en s e fab r i c s. H ig h s e t t in g tem p er a tu r e w h ich c r ea t e s a d eg r ee o f

s t if f n es s i n t h e f ab r ic d o es n o t r eco v e r w e l l f r o m c r eas in g o f d r y p o ly es t e r f ab r ic s .

S o m e c o m p r o m i s e i s n e c e s s a r y b e t w e e n t h e t e m p e r a t u r e n e c e s s a r y f o r m a x i m u m

d im en s io n a l s t ab i li t y an d th a t fo r an accep t ab l e d r y c r eas e r eco v e r y .



276 Heat -Set t ing

8.7 .5 Dyeabi l i ty

Fig . 8-8 sho ws a typical d i sperse dye uptake a t the boi l wi tho ut carr ier in theRo

5 0

d

12o 14o 1~o ~ o 20o z~o 22o ~.~o

H e a t - s e t t i n g temperature ~

Figure 8-8. The effect o f heat-setting temperatureon dye uptake

w hen p olyes ter is dyed wi th C. I .Disperse R ed 1 [33] .

dye bath in which d ye uptake var ies wi th the se t t ing temperature u sed wh en polyes-

ter is heat -se t . Al thou gh th i s pat tern o f beha viour i s general for a ll d i sperse d yes

appl ied to polyes ter , the shape and pos i t ion of the absorpt ion curve dep end o n the

m etho d of dyeing [34] ; the s ize , p lanar i ty an d polar i ty of d isperse dye ; pos i t ion o f

subs t i tuent groups and so lubi l i ty of dyes [35] . The absorpt ion of some dyes i s

pract ica l ly indepen dent of heat -se t t ing tem perature wh i l s t absorpt ion o f o thers is

h ighly sens i t ive to i t [36]. As the se t ting temperature i s increased , the curve show s

a redu ct ion in the ra te of dyein g for se tt ing temp eratures b etw een 130 and 150~

fol low ed by a level l ing-off . Ab ove about 190~ the ra te of dyeing r i ses rap id ly

and ev entual ly reache s values greater than that for unset c lo th . The in i t ia l decrease

in the uptake sugges t s that new crys ta l s are formed as se t t ing temperature i s in-

c reased by com ing toge the r o f we l l pa ra ll e l is ed cha ins i n the am orphous r eg ions

and am orphou s v olume per crys ta l decreases so the path for the dye par t ic les through

the am orph ous region i s very tor tuous . In the la ter s tages of crys ta l l isa t ion , the

crys ta l l i t es increase in s ize and a lso bec om e m ore perfect . Thus a t the h igher tem-perature of se t ting , the am orpho us volum e per crys ta l increases. Chain fo ld ing




a l so oc c u r s g iv ing r is e to s e g r e ga t ion o f c r ys t a l l ine a nd a m o r pho us r e g ions . Th i s

r e su l t s i n l e ss to r tuous pa th f o r the dye a nd p r ov ide e a sy pa s sa ge f o r the dye m ol -

e c u le . The de g r e e o f c r ys t a l l i n i ty a f f e c t s t he to t a l a m oun t o f dye tha t c a n be a b -

so r be d , wh e r e a s the de g r e e o f o r i e n ta t ion a f fe c t s the r a te o f dye ing . S ha r p inc r e a se

in dye a b i l i t y a bove 220 ~ i s t houg h t to be a s soc ia t e d wi th d i so r i e n ta t ion o f the

f ib r e a n d c a n n o t b e e m p l o y e d o n c o m m e r c i a l s c a l e b e c a u s e s m a l l d i ff e r en c e s i n

t e m p e r a t u r e m a y g i v e u n e v e n a d s o r p t io n o f d y e a n d r e p r o d u c i b i li t y o f t h e re s u l ts

w ou ld be ve r y poor . I n a dd i t ion t e ns ion , m o i s tu r e a n d tim e o f c on ta c t du r ing he a t -

se t ti ng a r e a l so im por t a n t f a c to r s tha t c a use v a r i a tion in the dye ing p r op e r t i e s o f t he

fibre.

The e f f e c t o f d i spe r se dye up ta ke on he a t - se t t e m pe r a tu r e o f po ly e s t e r i s a l so

a t t r ibu te d to the f ib r e be ing p u r i f i e d [37 ]. Pu r i f i c a tion ha s be e n v i sua l i s e d a s be ing

e i the r the e l im in a t ion o f d i -, tr i -, a nd t e t r a m e r s o r t he ir m e l t ing a n d c o a le se nc e to

f o r m g r e a te r d i s t a nc e s be tw e e n the bonds . The g r e a te r bon d d i s t a nc e s the n p r ov ide

f o r g r e a t e r vo ids c a us ing m o le c u la r vo ids . Th i s is c o r re l a t e d be tw e e n Tg a nd a p -

p a r e n t t r a n s i t io n t e m p e r a t u r e o f d y e i n g .

S t r uc tu r a l c ha nge s in ny lo n due to he a t - se t ti ng a f f e c t t he dye up take . S te a mt r e a tm e n t s i n c r e a s e t h e u p t a k e a n d r a te o f d y e in g w h e r e a s d r y h e a t c a u s e s s o m e

r e duc t ion . Th i s inc r e a se d dye r e c e p t iv i ty a nd he nc e lowe r a c t iva t ion e ne r g ie s in

s t e a m he a te d m a te r i a l s m a y be a t t r ibu te d to the m or e op e n s t r uc tu r e o f s e t ny lons .

I n the d r y se t t i ng , the m in im a o bse r ve d sugge s t s t ha t a t t he t e m pe r a tu r e a t wh ic h

decrea se in dye ing prop er t ie s occurs , the inc rease in c rys ta l l in i ty is impor tant ; how -

e ve r , the inc r e a se in dy e ing p r ope r t i e s a t the h ighe r t e m p e r a tu r e s sugge s t s a n op e n-

ing up o f the a m or ph ous s t r uc tu r e .

R E F E R E N C E S

1 R6"sch , Te xt i l Praxis , 27 (1972) 233.

2 F r ink e n a nd R e i f f , Te x t i l P r a x i s , 29 ( 19 74) 6 7 1 .

3 I C I , B P 1 ,32 7 ,6 6 1 ( 6 M a y 19 71).

4 Fr '~ ;l ich , M el l ian d Text i lbe r . , Che m iefa sem , 23 (1973) 729 .

5 Dogge t t , J . Soc . Dyers Colour is t s , 80 (1964) 80 .

6 Houben. , Mel l iand Text i lbe r . , 53 (1972) 808 .

7 F r a nke , C h e m ie f a se r n /Te x t i l i ndu s t r i e ( 19 7 2) 22 .



278 Heat-Sett ing

8 Franke, Chemicfasern/Texti l industr ie , (1974) 618.

9 Kra m er and Ste io, Ch em icfasem /Text i l indust r ie , (1974) 777.

10 Houben, Texti lveredlung, 9 (1974) 174.

11 An on., Int. Tex t. Bu ll. , No . 3 (1972 ) 231.

12 Anon. , Knit t ing Times, 40 (53) (1971) 147.

13 Gotte scha lk, Mell ian d Tex ti lber . , 53 (1972) 453.

14 An on., Int. Tex t. Bu ll. , No . 1 (1973 ) 59.

15 Ano n. , Dyer , 152 (1974) 41.

16 An on ., Int. Tex t. Bu ll. N o. 1 (1971 ) 57.

17 Anon., Dyer, 151 (1974) 290.18 Jacob, Dyer , 152 (1974) 256.

19 Harberr , Dyer , 151 (1974) 271.

20 Sch ellenb erger , Int . Text . Bull . , No. 1 (1974) 47.

21 Stacey, Hatranote, 14 (HA TR A) W oolard, 'C on trol ' (Shir ley inst itu te , 1972).

22 Ro bertso n, Int . Text . Bull . , No. 1 (1973) 78.

23 Me unier , Thom as and Hosche i t , Am er . Dy estu f fR ep . , 49 (1960) 53 .

24 Hea rle , Tex ti le Industr ies, (Aug 1969) 57.

25 Th om as and Holfe ld , Tex t i le Chem. C olor. , 4 (1972) 216 .26 M und en, J . Tex ti le Inst ., 50 (1959) T 448.

27 Holfe ld , "A A T C C Sym posium : Kni t Shrinkage; Cause , Ef fec t and Co ntro l ' ' ,

(Oct. 1973) 37.

28 Brow n, "A A T C C Sym posium : Kni t Shr inkage ; Cause , Ef fec t and Co ntro l ' ' ,

(Oct 1973) 12.

29 Bei r tz , Ch em iefasem , 20 (1970) 41 .

30 Tech . In f . Manual LF/1 /3 , Tery lene , F ibre Div is ion , Imper ia l Chemica l

Indus tr ies Ltd.31 M arvin , J. Soc. Dy ers Colourist , 70 (1954) 16.

32 N unn (Ed .) , The Dy eing of Synthe t ic Po lym er and Aceta te F ibres , Dyers Co .

Pub. Trust, (1979) p 177.

33 For tess e t a l., Amer . Dye stu f f R ep . , 50 (1961) 57 .

34 M erian, C arbonell , Ulerech and Sanah uja, J . Soc. Dy ers Co lourist , 79 (1963)

505.

35 Sa lb in , Am er . Dy estu f fR ep . , 54 (1965) 272 .

36 Hal l ida , Keen and Thom as, Amer . Dye stu f fR ep . , 50 (1961) 50.37 Olson and M e n o z a - Vergara , M. S . Thesis , Tex t i le Dept ., Col lege o f IM &

T.S. , Clem son Un ivers i ty , Clemson , SC, (1974) p 45 .



Chapter 9

M E R C E R I Z A T I O N

9 .1 I n t r o d u c t i o nM e r c e r i z a t i o n w a s d i s c o v e r e d b y J o h n M e r c e r i n E n g l a n d a n d t h e p r o c e s s i s

n a m e d a f t e r h i m : m e r c e r i z i n g . T h e p r o c e s s o f a l k a li n e t r e a t m e n t o f c o t t o n w a s

p a t e n t e d i n 1 8 50 . L a t e r H o r a c e L o w e i n E n g l a n d f o u n d t h a t t h e g la z i n g e f fe c t

b e c a m e e v e n m o r e p r o n o u n c e d w h e n c o l d c a u s t i c s o d a a c t e d o n c o t t o n u n d e r t e n -

s i o n . H e d i s c o v e r e d t h e a c t u a l m e r c e r i z i n g p r o c e s s a n d a p p l i e d f o r i ts p a t e n t i n

1890.

M e r c e r i z a t i o n g i v e s c o t to n w o v e n c l o t h a s il k y lu s t re , a n d i s t h e f o u n d a t i o n o f

m a n y i m p r o v e d a n d b e a u t i f u l fi n is h e s . S e w i n g an d e m b r o i d e r y c o t t o n y a r n s a re

m e r c e r i z e d w i t h t e n s i o n in t h e f o r m o f h a n k . S t r e t c h e d y a r n c a n b e m a d e b y m e r -

c e r i z i n g w i t h o u t te n s i o n [ 1, 2] . T h e s t r e tc h e d m a t e r i a l s a r e u s e d f o r b a n d a g e s ,

c a su a l w e a r ( o r i g i n a l l y g a r m e n t s f o r sk ii n g ) , sk i r ts , b o a t c o v e r s e t c . T h e i n c r e a s i n g

c o s t o f c h e m i c a l s , m a c h i n e r y , l a b o u r , e f f lu e n t c o n t r o l a n d r e c o v e r y o f c au s t ic s o d a

m a k e t h e p r o c e s s o f m e r c e r i z a t i o n l e s s a tt r a c ti v e n o w - a - d a y s .

9 .2 C o n d i t i o n s f o r M e r c e r i z a t i o n

M e r c e r i z a t i o n i s d e f i n e d a s t h e t r e a t m e n t o f c o tt o n t e x t il e s w i t h a c o n c e n t r a t e dso l u t i o n o f a l k a l i c o n s i s t i n g t h e f o l l o wi n g c o n d i t i o n s :

( a) A p p l i c a t i o n o f c a u s t i c so d a so l u t i o n a r o u n d 5 5 - 6 0~ ( ~- 3 1 t o 3 5 % ) a t a

t e m p e r a t u r e o f 1 5 t o 1 8~

( b ) A d we l l p e r i o d o f 55 s e c o n a n a v e r a g e , so as t o p e r m i t d i f f u s i o n o f a lk a l i

in to the f ib re .

( c) W a r p t e n s i o n d u r i n g a l k a li t r e a t m e n t a n d s t re t c h i n g t h e we f t ( w i d t h ) o f t h e

f a b r ic d u r i n g w a s h i n g a r e n e c e s s a r y t o p r e v e n t s h r i n k a g e .

( d ) F i n a l l y , wa sh i n g - o f f o f t h e t r a c e s o f a l k a l i f r o m t h e t r e a t e d f i b re s .

M e r c e r i z a t i o n m a y b e c a r r i e d o u t o n g r e y f i b r e s o r a f t e r s c o u r i n g / b l e a c h i n g .

T h e c l o t h s h o u l d b e s i n g e d b e f o r e m e r c e r i z i n g t o g i v e a s m o o t h s u r f a c e . I f

m e r c e r i z a t i o n i s c a r ri e d o u t in t he g r e y s t a te , c o m p l e t e r e m o v a l o f a l k a li i s n o t

n e c e s s a r y d u r i n g w a s h i n g t r e a t m e n t as t h e r e s i d u a l a lk a l i i n t h e c lo t h is u s e d f o r

t h e k i e r p r o c e s s . H o w e v e r , m e r c e r i z a t i o n i s c o m m o n l y c a r r ie d o u t a f te r s c o u ri n g ,

b u t i t is p r e f e r a b l e t o m e r c e r i z e a f te r b l e a c h i n g i f c o n t i n u o u s b l e a c h i n g p l a n t i s

ava i l ab le .



280 Mercer iza t ion

Ano ther necessary con di t ion for successful m ercerizat ion is the rapid and uniform

we t t ing o f the g rey c lo th . Pene t ra t ion o f a lka l i is h indere d by the h igh v i scos i ty o fthe s t rong caus t i c soda so lu t ion a t lower t empera tu re on the one hand and the

hyd rop hob ic na tu re o f the fa t ty m at te r p resen t in the s ize coa t ing as wel l as na tu ra l

fa t s and w axes p resen t in the f ib re on the o ther . To obv ia te these p rob lem s a smal l

am o u n t o f p en e t r a t i n g an d w e t t in g ag en t i s ad d ed to t he cau s ti c b a t h , . T h e w e t t in g

agen t s shou ld be se lec ted so tha t i t shou ld have good so lub i l i ty and h igh wet t ing

ab i l i ty in the a lka l ine ba th , shou ld have no af f in ity to f ib re , low foam ing po w er ,

g o o d e f f i c i en cy a t l o w co n cen t r a t i o n an d s t ab i l i t y u n d e r co n d i t i o n s o f s o d i u m

h y d ro x i d e r eco v e ry b y cen t r i fu g e o r v acu u m ev ap o ra t i o n t ech n i q u e e t c. [ 3] . It is

obv ious tha t a s ing le wet t ing agen t does no t show a ll these p roper t i es and , therefore ,

b lends o f we t t ing agen t s a re neede d to ge t the op t im um ef fec t dur ing merce r iza t ion

p ro ces s . G en e ra l ly , t w o t y p es o f w e t t i n g ag en t s ar e co mm o n l y u s ed i n me rce r i z i n g

l iquors e .g . c rys l i c ac id der iva t ives co upled w i th se lec ted so lven t s such as t r i e thy l

or t ribu ty l phosph ate and the o ther type i s non-cry s l i c type . Mix tures o f o r tho , m eta

and par a cre sols (also cal led crysl ic acid ), CH3-C6H4-OH, are not solub le in wa ter ,

bu t d i s so lve in s trong caus ti c soda so lu t ion s . The i r wet t ing pow er is a l so found tob e i mp ro v ed c o n s i d e rab l y b y i n co rp o ra t in g me t h y l a t ed sp i ri t, p o l y h y d r i c a l co h o ls

h av i n g CI8 ch a i n s , b u t a n o l , p o l y e t h y l en e g l y co l et c, b y d i mi n i s h i n g t h e v i sco s i t y

o f merc e r i z i n g l i q u o r. N o n -c ry s l i c w e t t in g ag en t s i n c l u d e s u l p h a t ed l o w er f a t ty

a lcoho ls such as hexy l o r oc ty l a l cohol a nd the add i t ion o f po ly hyd r ic a lcohols ,

enab le the s t ab i l i sa t ion o f we t t ing agen t s whi le avo id ing the i r p rec ip i t a t ion dur ing

the p rocess o f recov ery o f sod ium h ydrox ide . A product ob ta ined by the d i s t il l a tion

o f p i n e o i l a s a f r ac t io n b e t w een t u rp en t i n e an d ro s in , h a s e x ce l l en t w e t t i n g ,

pene t ra t ing and em uls i fy ing p roper t i es in m ercer iz ing l iquor. Wet t ing e f f i c iency of

non-cry s l i c type i s genera l ly h igher than tha t o fcry s l i c type . In case o fm erce r iza t ion

o f k n i t g o o d s w h i ch co n t a i n p a ra f f i n p ro d u c ts , t h e w e t ti n g ag en t s u s ed m u s t a l so

p o s s es s d i s p e r s i n g p o w er t o w ard s th e s e p ro d u c t s [ 4] .

9 .3 C h a n g e s i n t h e P r o p e r t i e s o f C e l lu l o s e D u e t o M e r e e r i z a t i o n

Cel l u l o s e u n d e rg o es c h em i ca l , p h y s i co -ch em i ca l an d s tru c tu ra l m o d i f i ca t io n s

on t rea tm ent wi th caus t i c soda so lu tion o f m ercer iz ing s t reng th [5 ] . Ch em ica l reac-

t ions l ead to the fo rmat ion o f a lka l i ce l lu lose , phys ica l reac t ions , to a change ina r r an g em en t o f u n i ts o f ce ll u lo s e . T h e o p t i m u m m o d i f i ca ti o n s i n th e p ro p e r t ie s o f



Mer ce r i za t i o n 2 81

ce l l u lo s e can b e m an ip u l a t ed w i th t h e s e l ec t io n o f p r o p e r co n ce n t r a t i o n o f a lk a l i,

t im e , t e n s i o n a n d t e m p e r a t u r e d u r i n g t he m e r c e r i z i n g p r o c e ss .

9 . 3 .1 S w e l l in g a n d s h r i n k a g e o f e e l lu l o s e

W h en ce l lu lo s e i s im m er s ed i n a so lu ti o n o f cau s ti c s o d a o f m er ce r i z in g s t ren g th ,

wa ter and a lka l i d i f fuses in and the mater ia l swel l s. The f ib re ha i r qu ick ly com m ence s

to u n tw i s t f r o m i ts tw i s t ed r i b b o n l i k e f o r m an d ten d s t o b ec o m e cy l in d r i ca l r o d -

l ik e s u r f ace d u e t o d eco n v o lu t i o n . T h e c r o s s - s ec t io n o f t h e f ib r e d im in i s h es , t h e

d i am e te r o f t h e f ib r e b ec o m es m o r e r o u n d . T h e s u r f ace o f t h e n ea r ly cy l i n d r ica l

co t ton f ib re a f te r m erce r iz ing r ef lec t s l igh t m ore even ly to a ll s ides than the k idne y-

s h ap e d co t t o n f i b re an d t h e f i b re s u r f ace b eco m es m o r e l u s t r o u s [6] . As th e f i b re

s w e l l s , t h e f i b r e s h r in k s i n l en g th [7 , 8 ] . Sw e l l i n g an d s h r in k ag e a r e m o r e w h en

there i s no tens ion in the f ib re , bu t the a l te ra t ion in c ross - sec t ion c ause d by sw el l ing

i s m o r e w h en m er ce r i za t io n i s ca rr i ed o u t u n d e r t en s io n . Un d e r o p t im u m co n d i t io n s

each co t t o n f i b re m a y co n t r ac t n ea r ly 9% in l en g th an d s w e l l n ea r ly 1 5 0 % . Sw e l l in g

o f t h e co t to n f i b r e a l s o h as a d i s ad v an t ag e . T h e f ib r e b eco m es m o r e co m p ac t i n i ts

s w o l l en co n d i t i o n . T h i s co m p ac t in g d im in i s h es t h e fu r th e r p en e t r a t i o n o f cau s t i c

s o d a i n to t h e f i b re i .e . p en e t r a t i o n s lo w s d o w n an d m er ce r i za t i o n i n t h e f i b e r 's co r ei s lower than on i t s su r face .

M a x i m u m s w e l l in g c o n c e n t r a t io n s o f d if f er e n t a lk a l ie s d e p e n d o n th e d e g r e e o f

h y d r a t i o n o f th e a lk a l i i o n [9, 1 0 ] . T ab l e 9 .1 co n t a in s d a t a o f d i f f e r en t k in d s o f

T A B L E 9 .1

E f f ec t o f Alk a l i M e ta l H y d r o x id es o n t h e S w e l l i n g o f Co t to n F ib r e [ 11 ]

R e a g e n t C o n c e n t r a ti o n o f a l k al i a t w h i c h

m a x i m u m s w e l l in g is o b t a in e dg/100 g o f so lu t ion mole /1

In c r eas e i n

f ib r e d i am e te r(%)

LiO H 9 .5 4 . 0 97

N aO H 1 8 .0 4 . 5 78

K O H 3 2 .0 5 .8 6 4

R b O H 3 8 .0 3 .8 5 3

C s O H 4 0 . 0 2 .7 4 7

a lk a l i m e ta l h y d r o x id es o n t h e s w e l l i n g o f co t t o n f ib r e . F o r s m a l l co n c en t r a t i o n o fa l k a l i , t h e d i a m e t e r o f t h e h y d r a t e d i o n s i s t o o l a r g e to p e n e t r a t e i n t o t h e



28 2 M e r c e r i z a t ion

m a c r om ole c u la r s t ruc tu re o f c o t ton , bu t a s the conc e n t r at ion inc r e a se s , t he num be r

o f wa te r m o le c u le s a v a i l a b le f o r the f o r m a t ion o f hydr a t e s de c r e a se s a nd thushyd ra ted ion pa i rs , d ipole hydra tes ( so lva ted or not ) a re formed w i th the dec reas ing

hyd rody nam ic d iamete r, a re capable of pene t ra t ing in to the f ibre s t ruc ture o f ce llu lose

f o r m ing hydr og e n bonds w i th the m o le c u la r cha ins o f c e l lu lose . Thus m e r c e ri z a tion

induc es imp or tant s t ruc tura l m odif ica t ion o f ce l lu lose when in te r f ibr i lla ry swel l ing

takes p lace . W ith fur the r inc rease in concent ra t ion o f a lka l i -meta l hydro xides in the

solu t ion , f ibre swe l l ing i s r edu ced due to dec rease in hydra t ion o f a lka l i m e ta l ions .

The in f lue nc e o f a lka li c onc e n t r a t ion a nd t e m pe r a tu r e o f t r e a tm e n t on swe l l ing

1 000

900

800

700

600

500

400

30O

200

100

Temperatures

- - - - 0 o C

A 7_ . . 20~

- . - - 6 0 o C

I0 . . . . . . . 2b . .. .. .. .. . 30 40

N a O H (W I W ) %

Figure 9-1. Depend ence of swell ing on temperature and concentra t ion of a lkali [12] .

o f c e llu lose a r e re p r e se n te d in F ig 9 .1 . The e x te n t o f swe l l ing de pe nds on the

c onc e n t r a t ion o f a lka l i. I n so lu t ion w i th a n inc r e a s ing c on c e n t r a t ion o f Na OH a t

20 ~ the swe l l ing o f c e l lu lose ( c o t ton lin t er s ) i nc r e a se s to a m a x im um va lue f o r a

c onc e n t r a t ion e qua l to 8 to 9% by w e igh t o f N a O H ; ne x t i t de c r e a se s to a m in im um

( 12 - 13% Na O H b y wt . ) a nd the n s lowly inc r e a se s in h ighe r c onc e n t r a t ion r a nge s .

T h o u g h 8 % N a O H ( b y w t .) so l u ti o n s g iv e m a x i m u m s w e l li n g , c o m m e r c i a l l y

m e r c e r i z a t ion i s done a t h ighe r c on c e n t r a t ion o f a bou t 31 to 35% w hic h ind ic a t e stha t swe l l ing i s no t t he on ly de te r m in ing f a cto r. Th i s i s be c a use o f p r e f e r e n t ia l



M e r c e r i z a t i o n 2 83

a b s o r p t i o n o f N a O H d u r i n g m e r c e r i z a t i o n p r o c e s s . T h i s p r e f e r e n t i a l a b s o r p t i o n i s

a s s o c i a t e d w i t h t h e q u e s t i o n o f c o m p o u n d f o r m a t i o n to f o r m s o d a - c e l lu l o s e . T h e

a m o u n t o f a l k a li a d s o r b e d i s v e r y m u c h g r e a t e r t h a n t h at o f p r e f e r e n t i a ll y a d s o r b e d

( F ig . 9 - 2 ) a s a r e su l t o f v e r y l a r g e sw e l l i n g a n d a d so r p t i o n o f wa t e r i n t h e c e l lu l o se .

T h e a d s o r p t i o n o f N a O H i s f o u n d t o b e c o n s t a n t b e t w e e n c e r t a i n c o n c e n t r a t i o n s o f

r .... -~ .......... r ... . T . .. .. F ...... Y .. .. .. ]I t t i ,

~ o I . . . . . . . ~ - . . . .. . - t . . . . . .. . .. 4 - . . . . _ L . _ . ~ _ o . . . . . . . . ~ .

t i . ~ i ! , ~ . i i : o i . t ~ i9 . . ~

. .. . .. .. . . . . + . . . .

i~ i l l~ ~ . . . . . . . .R~ .

. . . . L J _ _ m _ ' . _ L . . _ m o io 2 4 6 B 'K) 12 14-

M O t l h l y o f i i t k i t i i n f i n lt t ~ f o t u t iO l 3

F i g u r e 9 - 2 . N a O H a n d wa t e r a b s o r b e d b y c e l lu l o se sh e e t a t 2 5 ~ [ 1 3 , 1 4 ]. 1 - t o ta l

a l k a li a b s o r b e d , 2 - p r e f e r e n t i a l ly a b s o r b e d a l k al i, 3 - w a t e r a b s o r b e d .

a l k a l i , i t i s t h u s a s su m e d t h a t a d e f i n i t e c o m p o u n d i s f o r m e d wi t h t h e c e l l u l o sem o l e c u l e . F u r t h e r w a t e r a b so r p t i o n p l a y s a l a r g e p a r t a n d t h i s w a t e r a b so r p t i o n f a l l

r a p i d l y a f t e r r e a c h i n g a m a x i m u m , t h u s c a u s i n g a l k a li a b so r p t i o n to a p p e a r c o n s ta n t .

T w o b r o a d e x p l a n a t i o n s a r e p o s s i b l e f o r t he i n t e r a c ti o n o f c e l lu l o s e a n d c a u s t ic

so d a . F o r t h e f ir s t o n e , i t i s a s s u m e d t h a t c e l lu l o se c o m b i n e s w i t h c a u s t i c so d a to

f o r m a l k a l i - c e l l u l o se a n d swe l l i n g i s d u e t o th e m o l e c u l a r a t t r a c t i o n w i t h a s so c i a t e d

C6H904 - O H + N a O H --+ C6H904 - O N a + H20

A l k a l i - c e l l u l o s e

h y d r a t i o n . T h e e x t e n t o f t h i s c o m b i n a t i o n i s g o v e r n e d b y t h e c o n c e n t r a t i o n o f a l k al i.

I t i s a s s u m e d t h a t a l k a l i - c e l l u l o s e i s m o r e h y d r a t e d t h a n t h e n a t i v e c e l l u l o s e .

M a x i m u m s w e l l i n g i n p a r t ic u l a r r a n g e o f a l k a li c o n c e n t r a t i o n i s t h e r e su l t o f t h e

a t t r a c t i o n o f a l k a l i - c e l l u l o se o n t h e o n e h a n d a n d t h e r e m a i n i n g f r e e a l k a l i o n t h e

o t h e r . T h e h y d r a t i o n o f t h e c e l lu l o se i n c r e a se s w i t h t h e i n c r e a se d f i x a t i o n o f a l k a l i

i n so l u t i o n s o f r i s i n g c o n c e n t r a t i o n s u p t o a c e r t a i n l i m i t , a f t e r w h i c h f r ee a l k a l i

e x e r t s a d e h y d r a t i n g e f f e c t o n t h e a l k a l i - c e l l u l o se t o a g r e a t e x t e n t . T h e s e c o n d

t h e o r y i s b a s e d o n o s m o t i c p h e n o m e n a . I t is a s s u m e d t h a t c e l l u lo s e b e h a v e s a s av e r y m o n o b a s i c a c i d d u e to t h e h y d r o x y l g r o u p s i n it a n d f o r m s a n a l k a l i -c e l l u l o s e




dur ing m e r c e r i z a t ion wi th a lka l i . The e xc e ss a lka l i d i f f use s in to the c e l lu lose

a c c o r d i n g t o D o n a n ' s th e o r y o f m e m b r a n e e q u i l ib r iu m . T h e p r e s e n c e o f i o n s i nc e l lu lose r e su l t i n une q ua l d i s t r ibu t ion a nd thus b r ings a bo u t a n osm o t i c p r e s su r e .

Th i s c a use s wa te r t o e n te r t he f ib r e un t i l suc h t im e a s the osm ot i c p r e s su r e i s i n

ba la n c e w i th the r e s t r a in ing o r e la s t ic f o r c e s o f t he swo l l e n f ib re . W he n the a lka li

so lu t ion i s r e p la c e d by a l a rge e xc e ss o f wa te r , t he sod ium c e l lu losa t e i s hydr o lyse d ,

osm ot ic pressure fa ll s , und issoc ia ted hydrox yl groups a re re form ed and the ce l lu lose

is recov ered c hem ica l ly unchanged, but pe rman ent ly d is tor ted i f the osmo t ic pressure

is h igh enou gh. Ano ther te rm is t r ans ient swe l ling . W hen a lka li impregn a ted mate r ia l

i s wa she d wi th wa te r , i nc r e a se d swe l l ing i s obse r ve d wh i l s t t he a lka l i i s be ing

r e m ov e d ( F ig . 9 - 3 ). W a te r d i f f use s in to the c e l lu lose m or e r a p id ly tha n the a lka l i

ions c a n d i f f use ou t , a nd he nc e , s inc e the a c t iv i ty o f the wa te r i n the a q ue ous p ha se

. - 'K)

o l o

8

c_ 0o

W A T E R

f* - - - - - " . . . . . . . . .. . l O . 7 t ~ f N a O H . . . . . . . . . . ~ " ' q - - - t ' 4 1 j ~ )

3 0

T~'r,e (rain)

Figur e 9 - 3 . T r a ns i e n t sw e l l ing o f c e l lu lose [15] .

i s i nc r e a se d , t he osm ot i c p r e s su r e i s t r a ns i to r ily l a rge r . Th i s g r e a t e r m om e n ta r yswe l l ing wh ic h oc c u r s f o r a sho r t pe r iod o f t im e de c r e a se s a s the ions d i f fuse s ou t

o f the f ib r e . I f t he a c t iv i ty o f w a te r i n the wa sh l iquor is r e duc e d by the a dd i t ion o f

sa lt , t he sw e l l ing e f f e ct s a r e r e duc e d a nd the a lka l i m a y be r e m ov e d w i thou t undu e

sw el l ing of the f ibe r [ 16 ] .

S w e l l ing o f c e l lu lose f ib r e s in a lka l i i nc r e a se s w i th a de c r e a se in te m pe r a tu r e

[ 17] a s the f o r m a t ion o f a lka l i - c e l lu lose c om pou nds i s a n e xo the r m ic p r oc e ss . A t

0~ the sw el l ing of ce l lu lose in a lka l i (8 -9% by w eight) i s abou t 800% (Fig . 9 -1)

a n d s w e l l i n g d e c r e a s e s r a p i d l y a t h i g h e r c o n c e n t r a t i o n o f a l k a l i d u e t o t h e

de c r ys t a l l i s a t ion o f N a O H hydr a te s . The e x te n t o f swe l l ing a l so de c r e a se s a s the



Me rc e r i z a t i on 28 5

9 0

80

70

-~ 60.=_

Z " 5 0._

4 0

30

2 0

t r e a t me n t t e mpe ra t u r e i nc re a s e s ( 60 ~ o r 100 ~ a nd m a x i m um s w e l l ing i s obs e rve d

a t 7 - 8 % N a O H b y w e i g h t .

S h r i n ka ge o f c o t t on i s g r e a t e s t on s w e l l i ng i n a l ka li at 15 -18~ a nd t he va l ue

decrea ses wi th inc rease in t emp era ture . The use of co ld (2~ conc ent ra ted so lu t ions

o f a l ka l i r e duc e t he s h r i nka g e a s t he s o l u ti ons be c o m e t oo v i s c ous t o i mpre g na t e

f i b r e s s i gn i f i c a n t l y i n a s ho r t t i me . The s h r i nka ge o f r a w c o t t on f i b r e is l ow e r t ha n

t ha t o f s c oure d c o t t on [ 18] . V o l um e c h a nge s a r e s i gn i f i c a n t r a ng i ng f rom 6 2c c to

177 i 8cc in the a lka l i con cen t ra t ion s rang ing f rom 14.3 to 48 .8% (w/w ) [7] . Th e

i nc re a s e i s , how e ve r , s ma l l i f t r e a t me n t i s c a r ri e d ou t unde r t e ns i on .

9 . 3 .2 S t r u c t u r a l m o d i f i c a t i o nD ue t o s w e l l i ng o f c e ll u l os e i n ca us t i c s oda s o l u t ion o f m e rc e r i z a t i on s t r e ng th ,

m a n y h y d r o g e n b o n d s a r e b r o k e n , t h e p l a n e o f m o l e c u l a r c h a i n s h a v e b e e n m o v e d

apar t , m olecu la r s t ruc ture t ends to bec om e decrys ta l li s ed , the cha ins or spaces wi th in

t h e c e ll u l o se s t ru c t u re b e c o m e m o r e u n i f o r m a n d th e c h a i n s o f g l u c o s e r e si d u e s

h a v e b e e n g i v e n a s li g h t t w is t. B e c a u s e o f t h e d is t o rt io n o f p o l y m e r n e t w o r k a n d

c h a n g e s i n c ry s t a l li n e s t ru c t u r e , t h e p r o c e s s o f m e r c e r i z a a t i o n i s i r r e v e r s ib l e

[ 19-23] . M erc er iz a t io n a l so a f fec t s the s ize of the c rys ta l l i t e s [24] and or ienta t io n

of the c rys ta l l ine regio n [25 , 26 ] and the extent of or ien ta t ion d epen ds on the tens iondur i ng me rc e r i z a t i on . The i n f l ue nc e o f a l ka li c onc e n t r a t i on on c ha n ge s i n t he

c rys t a l l i ne s t ruc t u r e o f c o t t on ya m s me rc e r i z e d fo r 6 0 s e c s a t 20 ~ w i t h c ons t a n t

l ength (0% s t re tch) is i l lus t ra ted in F ig . 9 -4 . Sod a-Cel lu lose I i s form ed w i th sodiu m. . . .

. . . . . . . T o ta l c r y s ta l l i n i t y

C e l l u l o s e I

10

C e l l u l o s e I I

1 0 0 2 0 0 3 0 0

N a O H c o n c e n t r a t i o n ( g / l)

F i g u r e 9 - 4 . I n f lu e n c e o f N a O H c o n c e n t r a t io n o n th e

crys ta l l ine s t ruc ture of ce l lu lose f ibres [27 ] .




hydr ox ide a t c onc e n t r a t ions o f 12 - 19 % ( by wt . ) [28 - 30 ] , S oda - C e l lu lose I I a t

c on c e n t r a t ion s be twe e n 20 a nd 45% by we igh t . C e l lu lose I e x i s t s i n a pa r a l l e lc ha in c o nf o r m a t ion w h i l e C e l lu lose I I e x i s t s in a n a n t ipa r a l le l c ha in c on f o r m a t ion

[31 ] . S oda - C e l lu lose I I I i s ob ta ine d by d r y ing S oda - C e l lu lose I [32 , 33 ] . Fo r

t e m p e r a tu r e h ighe r tha n 30 ~ a nd in so lu t ion 20 - 25% Na OH ( by wt .) , t he f o r m a t ion

of S oda - C e l lu los e I II a nd II i s ob ta ine d [34] . S od a - C e l lu lose I V is ob ta ine d by

w a sh ing S od a - C e l lu lose I a nd II i n w a te r o r i n d ilu t e so lu tion o f N a OH [35] . S oda -

C e l lu lose V a ppe a r s be twe e n - 10 a nd +20~ in a w ide ra nge o f N a O H c on c e n t r a tions

o f a bou t 40 - 45% ( by wt . ) [36 - 38 ] . Howe ve r , c onc e r n ing the f o r m a t ion o f S oda -

C e l l u l o s e c o m p o u n d s t h e r e is s o m e a p p r o x i m a t i o n th e m a n n e r i n w h i c h t h e y f o rm

wi th r e spe c t to the na tu r e o f N a O H hy dr a te s p r e se n t i n c onc e n t r a t e d so lu t ions .

C e l lu lose I c on te n t a nd to t a l c r ys t a l l i n i ty inde x de c r e a se s a s the t e m pe r a tu r e o f

m e r c e r i z a t ion inc r e a se s , wh e r e a s C e l lu lose I I f o l lows a n oppos i t e c ou r se due to the

b e t t e r p e n e t r a t io n o f N a O H h y d r a t es . M e r c e r iz a t i o n w i t h o u t t e n s i o n a l lo w s t o ta l

c on ve r s io n o f C e l lu lose I t o C e l lu lose I I t o ta ke p l a c e , wh e r e a s w he n m e r c e r i z ing

wi th t e ns ion , m ix tu r e s o f t he two a r e f o r m e d [39, 40] . C e l lu lose I I I, IV a nd X c a n

a l so b e o b t a in e d b y tr e a t m e n t o f c o t to n w i t h a m m o n i a a t -3 5~ h o t g l y c er i n e a n dpho sph or i c a c id r e spe c t ive ly . The sha pe o f na t ive c e l lu lose c rys t a l ( C e l lu lose I) i s

m onoc l in i c a nd the d im e ns ions o f m ono c l in i c un i t ce l ls o f va r ious c r ys t al l ine f o r m s

( C e l l I t o C e l l X) a r e sh ow n in Ta b le 9 .2 . Ou t o f va r ious C e l lu lose s , C e l lu lose I I is

m o s t s t ab l e a n d t h e o t h e r C e l lu l o s e s m a y b e r e c o n v e r t e d i n t o e a c h o t h e r [ 4 1 , 4 2 ] .

T A B L E 9 . 2

D i m e n s i o n s o f U n i t C e l l o f D i f fe r e n t C e l lu l o s e s o n S t ru c t ur a l M o d i f ic a t i o n

Dim e ns ion s C e l lu lose I C e l lu lose I I C e l lu lose I II C e l lu lose I V C e l lu lose Xa( A ) 8 .35 8 .14 7 .74 8 .11 8 .10

b ()k) 10.30 10.30 10.30 10.30 10.30

( f ibre axis )

c (A) 7 .9 9 .14 9 .9 7 .9 8 .16

[3 (de gre es) 84 62 58 90 75.3 6

9 . 3 .3 I n c r e a s e d l u st r e

Un m e r c e r i z e d c o t ton ha s a ge ne r a l a ppe a r a nc e o f a f la t r i bbon w i th sp i r al tw i s ts ,

i ts su r f a c e i s r oug h a nd non - un i f o r m , i t s c r os s - se c t ion i s i rr e gu la r a nd e a r - sha pe d




w h i l e t h e l u m en , t h e cen t r a l can a l , i s b r o ad , i r r eg u l a r an d r e s em b les a co l l ap s ed

tu b e . A l l th e s e f ac to rs re s u l t i n l e s s l u s tr e . W h e n a co t to n h a i r is b r o u g h t i n to ana q u e o u s s o l u ti o n o f s o d i u m h y d r o x i d e o f 1 8% ( 4 0 ~ c e l lu l o s e b e g i n s t o s w e l l

im m ed ia t e ly , t h e h a i r is e ll i p ti ca l i n s ec t i o n i n a f ew s eco n d s , an d o n f u r th e r s w e l l -

i n g b ec o m es c i r cu l a r an d t h e l u m en i s p r ac t i ca l ly e l im in a t ed . T h e u n tw i s t i n g o f t h e

f ib r e t a k e s p l a c e u n d e r e f f e c t o f s w e l li n g a n d i n c r e a s e d a l i g n m e n t a n d p a c k i n g o f

th e f i b r e s i n t h e y am a l s o t ak e p l ace . T h e ch an g es t h a t t ak e p l ace i n t h e c r o s s -

s ec t i o n a l s h ap e o f co t t o n f i b re d u r in g m er ce r i za t i o n a r e s h o w n in F ig . 9 .5 . S t ag es 1

. . . . . .

9 - ~ - , F "

8 1 0

1 2 ~ 4 5 6 7

Figure 9-5 . Seven successive stages o f change in the cross-sectional

s h ap e o f a co t t o n f i b r e a s p r o d u ced d u r in g m e r ce r i za t i o n .

t o 5 s h o w th e ch an g e f o r a tw i s t ed r i b b o n l i k e f i b r e t o o n e w h ich i s u n i f o r m ly

cy l in d r i ca l a n d i n i ts m o s t s w o l l en f o r m a t 5. S t ag es 6 an d 7 s h o w s o m e co n t r ac -

t i o n b u t w i th o u t l o o s in g i t s cy l i n d r i ca l f o r m w h en th e f i b r e i s w as h ed w i th w a te r

(6) and then d r ied (7). Du r ing the las t th ree s tages , the ha i r r e ta ins the sam e fo rm o f

s e c ti o n , b u t s h r i n k a g e p r o c e e d s u n i f o r m l y t o w a r d s t h e c e n tr e a n d l u m e n d o e s n o t

rec ov er i ts o r ig ina l s ize . B ut to secure an increase in lus t r e the co t ton ma ter ia l mu s t

b e p r e v e n t e d f r o m s h r in k a g e b y s t re t c h in g t h e y a m l e n g t h w i s e a n d t h e f a b ri c b o t h

l e n g t h w i s e a n d w i d t h w i s e d u r i n g t h e tr e a t m e n t a n d w a s h i n g o u t o f t h e a l k al i b y

w a t e r . W h e n c o t to n i s m e r c e r i z e d w i t h o u t t e n si o n , th e fi b re w h i l e m u c h s m o o t h e r

an d r o u n d e r w i th l i t t l e o r n o tw i s t , s t i l l s h o w r e s id u a l c r eas es an d w r in k l e s an dth e r e i s n o a p p r ec i ab l e i n c r eas e i n l u s t re a s th e c r o s s - s ec t i o n i s o v a l an d l u m en i s

co n t r ac t ed b u t n o t co ll ap s ed . Lu s t r e i n c r eas es a s t h e t en s io n ap p l i ed t o th e f i b re

d u r in g m er ce r i za t i o n i s in c r eas e d [4 3 , 4 4 ] .

Lu s t r e a l s o d ep en d s o n o th e r fac to r s. M er ce r i za t i o n r ed u ces t h e ax i a l r a t io an d

in c r eas e t h e l i g h t s ca t t e r i n g w i th in t h e f ib r e ( t r an s p a r en cy ) an d t h u s i n c r eas es t h e

lu s tr e . T h e p r e s e n ce o f s h o r t fi b re o n th e s u r f ace d ec r eas es l u s t r e an d i s r em o v e d

d u r in g s in g e in g . Lu s t r e i n c r eas es f r o m 1 80 g/1 o f N aO H s o lu t i o n t o a m ax im u m a t

2 60- 3 00 g / l , t h en d ec r eas es s l i g h t l y [ 4 5 ] . T h eo r e t i ca l l y l u s t r e i n c r eas es w i th an

i n c r e a se i n s w e l l in g a n d t h e re f o r e w i t h a d e c r e a se i n th e t e m p e r a t u r e o f m e r c e r i z a -




t ion [46] . Ho we ve r , i f t he te m pe r a tu r e i s de c r e a se d , t he r e w i l l be su r f a c e d i s so lu -

t ion o f the f ibre wh ich m ay resul t in a dec rease in lus t re [44] . On the cont ra ry , lus t reinc r e a se s w i th inc r e a se in t e m p e r a tu r e o f m e r c e r i z a t ion [47, 48 ] in sp i te o f l owe r

swe l l ing va lue . Th i s m a y be due to the f a st e r a nd un i f o r m pe ne t r a t ion o f N a OH a t

h ig her temp era ture . Th e s tap le length o f the cot ton is a lso s igni f icant s ince the long

s ta p le f ib r e ha s the be s t sha pe o f c r os s - se c t ion . Tw is t e d doub le ya r n i s m o r e lu s -

t r ous a f t e r m e r c e r i z a t ion tha n non- tw i s t e d loose ya m . A f a ce c lo th suc h a s s a t e e n

wi l l sh ow the g r e a te s t i nc r e a se in lu s t r e a nd i s c a use d by the long f loa t s l e nd ing

the m se lve s to the e f f e c tive t e ns ion m or e r e a d i ly tha n sh o r t e r c r os s ings o f the ya rn .

9 . 3 . 4 G a i n i n s t r e n g t h

M e r c e r i z a t ion , bo th s l a c k a nd wi th t e ns ion , i nc r e a se s the s t r e ng th un i f o r m i ty

a long the f ib re l e ng th [49 ], bu t m e r c e r i z e d f ib r e w i th t e ns ion show s g r e a te r ga in in

s t r e ng th tha n tha t o f w i thou t t e ns ion . I n p r a c t ic e , t he im pr ov e m e n t s in s tr e ng th a r e

no t i c e d m os t ly up on ya r n t r e a tm e n t s , w i th f a b ri c the m a jo r e f f e c t i s on the su r f a c e

only . M ercer iza t ion inc reases the tens i le s t rength of co t ton f ibres by e l imina t ing the

w e a k e s t po in t s i n the f ib r e [50, 51 ] . M e r c e r i z a t ion inc r e a se s the c ohe s ion be twe e n

ind iv idu a l c o t ton ha i r s a nd th i s c lo se r e m be dd ing o f the ha i r s i n the ya m no t on lyinc r e a se s the s t r e ng th bu t m a k e s i t m or e u n i f o r m in s tr e ng th a nd l e s s in d i a m e te r .

The phy s ic a l p r ope r t i e s o f m e r c e r i z e d f ib re s a r e re l a t e d to the o r i e n ta t ion f a c -

tor ; the You ng ' s m odu lus inc reases w i th inc rease in or ien ta t ion . Th e e long a t ion ac ts

in reverse , dec reas ing as the or ien ta t ion inc reases [52 , 53] . Th e inc rease in or ien ta -

t ion o f the c r ys t a l li t e s w i th r e spe c t t o f ib re a x i s c a n be a t t ribu te d to suc h f a c to r s a s

the r e duc t ion in c r ys t a l li n i ty o f t he f ib re , t he de c r e a se in l e ng ths o f c r ys t a l l it e s a nd

f ib r e de c on vo lu t ion [54, 56 ] . I n c a se o f s la c k m e r c e r i z e d c o t ton inc r e a se d s t r e ng th

i s a c c o m pa n ie d by a n inc r e a se in e x te ns ib i l it y , t hus de c on vo lu t ion i s no t t he on ly

f a c to r in f lue nc ing the c ha ng e s in m e c ha n ic a l p r ope r ti e s on m e r c e r iz a t ion a pa r t f r om

de c r ys t a l l i s a t ion a nd l e ng th o f c r y s t a l l i t e s [57] .

The tw i s t o f ya r n p l a ys a n im po r t a n t r o le a nd low tw i s t a ppe a r s to be e s se n t i a l

f o r m a x im um inc r e a se in s t re ng th . Gr e y ya m wi th so f t doub l ing tw i s t g ive s s t ron -

ge r ya r n .

9 . 3 . 5 I n c r e a s e d m o i s t u r e a b s o r p t i o n

M e r c e r i z e d c e l l u l o s es a b s o r b m o r e w a t er , h a v e h i g h e r r e g a i n s a n d m o r e e a s il ywe t ou t t ha n unm e r c e r i z e d f ib r e s . Due to c aus t i c soda pe ne t r a t ion , m a ny hy dr og e n




b o n d s a r e b r o k en an d i t i s e s t im a ted t h a t t h e n u m b er o f av a i l ab l e , h y d r o x y l g r o u p s

a r e i n c r eas e d b y ab o u t 2 5 %. M er ce r i za t i o n , t h u s d ec r eas es th e am o u n t o f c r y s t a l -

l in e p a r t o r i n c r eas es t h e am o r p h o u s co n t en t o f t h e fi b re . T h i s i n c r eas e i n th e

p r o p o r t i o n o f am o r p h o u s p a r t i s d i r ec t l y r e l a t ed t o t h e m o i s tu r e s o r p t i o n . M o i s -

tu r e is a s s u m ed to b e ab s o r b ed b y s u i t ab l e g r o u p s i n t h e am o r p h o u s r eg io n an d o n

th e s u r f ace o f t h e c r y s t a ll i te s . W h en m er ce r i za t i o n i s ca r ri ed o u t u n d e r t en s io n , t h e

ch an g es i n c r y s t a l li n e p o r t i o n i s co m p ar a t i v e ly l o w er t h an th a t w i th o u t t en s io n an d

h en c e a l s o t h e m o i s tu r e s o r p t i o n . S t an d a r d co tt o n h as m o i s tu r e co n t en t o f ab o u t

7%, m e r ce r i ze d co t t o n w i th ten s io n h as ab o u t 9% an d th a t o f w i th o u t t en s io n ab o u t

11%.

9 .3 .6 Increased dye adsorpt ion

M er ce r i ze d co t t o n s h o w s in c r eas ed d ep th o f s h ad e , i n c r eas ed r a t e o f d y e in g an d

th e i r reg u l a r i t i e s d u e t o n ep s an d u n r ip e co t t o n a r e l e s s p r o m in en t . Gen e r a l l y im -

m a tu r e co t t o n w i th l a r g e l u m en r e s p o n d s p a r t i cu l a r ly w e l l t o i n c r eas ed l i g h t s ca t -

t e r in g a n d h e n c e d e c r e a s e d d y e u p t ak e . T h e g r e a t e r c o l o u r y i e l d o n m e r c e r i z e d

co t to n t ak es p l ace t o d i f f e r en t d eg r ees a t d i f f e r en t d ep th o f co lo u r s [ 5 8 ] an d t h e

m ag n i tu d e o f i n c r eas ed d e p th o f s h ad e v a r ie s f o r d i f f e ren t d y es tu f f s [ 5 9 ] . T h ein c r eas ed d ep th o f sh ad e o f m er ce r i ze d co t t o n h as b een a t t ri b u t ed t o o p t i ca l e ff ec t s

a r i s i n g f r o m th e m o d i f i ca t i o n s o f fi b r e s ize an d s h ap e [60, 61 ] an d t o ch an g e s i n

in terna l l igh t sca t te r ing [62] , as wel l as to ac tua l increases in dye con ten t due to

in c r eas ed am o r p h o u s p a r t o f t h e f ib r e . Ab o u t h a l f th e t o ta l d y e s av in g s i s a t t ri b u t ed

to o p t i ca l e f fec t s . T h e ch an g e i n p o r e v o lu m e an d r ed u c t io n i n l u m en d i am e te r a r e

p r i m a r y c a u s e s o f c o n s e q u e n t i m p r o v e m e n t i n c o l o u r y i e l d a n d re d u c e d l i g h t sc a t-

t e r i n g w i th in th e f ib r e . M er ce r i za t i o n t h u s l o w er s th e d y e co st s , s av in g s a t 2 %

d e p t h a v e r a g e d 4 0 % , w h i l e a t 6 % w i t h th e s a m e d y e s t h e a v e r a g e s a v i n g i s a b o u t

6 0 % .

Co t to n can b e cau s t i c i zed o r h a l f - m er ce r i zed t o i n c r eas e t h e d y e u p t ak e an d

e c o n o m i c s u p to 2 5 % m a y b e r e a li s ed . S e m i - m e r c e r i z a ti o n o r c a u s ti c i z a ti o n i s

ca r r i ed o u t i n cau s t i c so d a s o lu t i o n b e tw een 2 5 an d 3 0~ a t a t em p er a tu r e o f 2 0 -

2 5 ~ s o m e t im es w i th o u t s t r e t ch in g t h e c lo th t o r e s to r e o r ig in a l d im e n s io n s . So -

d iu m h y d r o x id e s o lu t io n ab o v e 3 0~ th e r a te o f co lo u r ab s o r p ti o n d ec r eas es . Sem i -

m er ce r i za t i o n i s a l s o an im p o r t an t s t ep w h er e h eav y s h ad es a r e r eq u i r ed w i th t h eex p e n s iv e v a t co lo u r s . Be t t e r r e s u l t s a re a l so o b s e r v ed w i th an i l in e b l ack o n g o o d s

w h i c h h a v e r e c e i v e d a s e m i - m e r c e r i z a t i o n t r e a tm e n t .



2 9 0 M e r c e r i z a t i o n

9 . 3 . 7 I n c r e a s e d r e a c t i v i t y

T h e r e a c t i v i ty o f m e r c e r i z e d c o t t o n i s in c r e a s e d b y a b o u t 1 I / 2 t i m e s a t l o w e rt e m p e r a t u r e i n c o m p a r i s o n t o t h a t o f u n m e r c e r i z e d c o tt o n. T h e i n c r e a s e d r e a c ti v i ty

i s n o t s o m a r k e d w h e n m e r c e r i z a t i o n i s c a r r ie d o u t u n d e r t e n s io n . T h e r e a c t i v i t y

r a t i o i s g e n e r a l l y r e f e r r e d t o a s t h e r a t i o o f c o p p e r n u m b e r o f t h e m e r c e r i z e d t o

u n m e r c e r i z e d s a m p l e s . T h e i n c r e a s e d r e a c t i v it y i n c r e a se s d y e a b s o r p t io n , m o i s -

t u r e so r p t i o n a n d c h e m i c a l r e a c t i o n , b u t a t t h e s a m e t i m e i t a l so a c c e l e r a t e s t h e

r e a c t i o n w i t h a c i d s a n d o x i d i s i n g a g e n t s a n d i s su sc e p t i b l e t o d e g r a d a t i o n .

9 .3 .8 R e m o v a l o f i m m a t u r e c o t t o n

M e r c e r i z a t i o n h a s b e e n r e c o g n i s e d a s a m e t h o d f or r e m o v i n g i m m a t u r e ( d e a d)

f i b r e s to o b t a i n l e v e l d y e i n g e f f e c t o n c o t to n f a b r i c s . T h e d e a d f i b r e s a re u n d e r d e -

v e l o p e d a n d a p p e a r a s f l at o r s l i g h t l y t w i s t e d t a p e s . T h e y a r e n o n - c r y s t a l l i n e , c o n -

v o l u t i o n s a r e s o m e t i m e s a b s e n t , c el l w a l ls a r e e x t r e m e l y t h in a n d t h e l u m e n is c o l-

l a p s e d a n d h e n c e d o n o t c o n t a i n d y e t o s a m e e x t e n t a s m a t u r e d f ib r es .

9 . 3 . 9 P h y s i c a l c o m p a c t n e s s

M e r c e r i z a t i o n i m p r o v e s d i m e n s i o n a l s t a b i li ty o f c o t to n wo v e n f a b r i cs [ 63 ] . W h e n

k n i t t e d f a b r ic s a r e c o m p a r e d w i t h r e s p e c t t o th e i r r e l a ti v e o p e n n e s s , t e m p e r a t u r ei n c r e a se s c a n b e s a i d t o im p r o v e m e r c e r i z a t i o n b e c a u se w h e n t h e g o o d s a r e b l e a c h e d

a n d th e n m e r c e r i z e d , th e f ab r ic b e c o m e s m o r e d e n se . H o w e v e r , w h e n u n b l e a c h e d

f a b r ic s a r e m e r c e r i z e d , t h e f ab r i cs b e c o m e m o r e o p e n [ 6 4 ]. M e r c e r i z a t i o n a l so

g i v e s m o d e r a t e i m p r o v e m e n t i n c re a s e r e c o v e r y o f c o t to n f a b r i cs [ 65 ] a s w e l l a s

so m e p r o t e c t i o n a g a i n s t t h e d e c r e a se i n te n s i l e s t r e n g t h c a u se d b y e a s y - c a r e f i n i sh -

ing.

9 .4 M e r c e r i z a t i o n o f R e m i e a n d F l a x F ib r e s

R e m i e a n d f l a x a r e o f t e n u se d i n t h e s a m e f a b r i c a t i o n s a n d a r e o f t e n b l e n d e d

w i t h c o t t o n to i m p r o v e i t s p e r f o r m a n c e . I n f o r m a t i o n s a s a r e s u l t o f c o m m o n c o n -

d i t io n s o f m e r c e r i z a t i o n a r e o f g r e a t in t e r es t t o m i n i m i s e t h e v a r i a t io n i n d y e i n g

b e h a v i o u r f o r t h e t h r e e n a t u r a l c e l l u l o s i c f ib r e s . F l a x f ib r e s g e n e r a l l y p o s se s s a

h i g h d e g r e e o f l u st re a n d m e r c e r i z a t i o n i s g e n e r a l ly d o n e t o i m p r o v e t h e a ff i n it y o f

d y e s t u f f s , a s s i s t i n t h e c r e a se - r e s i s t i n g p r o c e s s , i m p r o v e a b r a s i o n r e s i s t a n c e a n d

c o v e r t h e r e e d i n e s s i n c lo t h a s s o c i a t e d w i t h y a r n u n l e v e l n e s s .

T h e e f f e ct s o f s l a c k a n d t e n s io n m e r c e r i z a t i o n o n t h e m o r p h o l o g y a n d a c c e s s i-b i l i t y c h a r a c t e r i s t i c s o f r e m i e , f la x a n d c o t t o n f i b re s a r e c o m p a r e d [ 66 ] . M e r c e r -




ized r em ie i n c r eas es i n s i ze b u t n o t i n c i r cu l a r i t y ; m er ce r i zed f l ax f i b r e s d o n o t

increase in s ize o r shape; merc er ize d co t ton f ib res increase in a rea and in c i r cu lar i tyas a r e s u l t o f s w e l l i n g i n cau s t i c s o d a . T h e ch a n g es o ccu r in g i n li n en [67, 68] an d

f l ax [69 , 70 ] fi b r e s h av e b een r ep o r t ed . S l ack m er ce r i za t i o n s o f r em ie an d f l ax

r e s u l t in co n s id e r ab l e l o s s e s i n y a m s t ren g th , w h i l e t en s io n m er ce r i za t i o n s r e s u l t in

in c r eas e d s t r en g th . In c r eas e d y a r n s t r en g th i s s een in b o th s l ack an d t en s io n m er -

ce r i za t i o n o f co t t o n y am . In c r eas es i n f ib r e acces s ib i li t y a r e o b t a in ed i n al l m er ce r -

i zed f i b re s , b u t t h e m ag n i tu d e o f ch an g e i n fl ax is ap p r o x im a te ly h a l f o f t h a t in

r em ie an d co t t o n . C h an g es i n f ib r e s h ap e an d acces s ib i l it y ch a r ac t e r i s t i c s a r e l o w er

w h en ce l l u lo s e y a r n s a r e h e ld u n d e r co n s t an t ten s io n t h an w h en th ey a r e a l l o w ed to

s h r in k fr ee ly d u r in g m er c e r i z in g t r ea tm en t . M er ce r i za t i o n o f r em ie r e s u l t s in a

co m p le t e co n v e r s io n o f Ce l lu lo s e I t o Ce l lu lo s e I I an d a d ec r eas e i n t h e d eg r ee o f

c r y s t a l l i n i t y t o 5 0% [71 ] . T h e o r i en t a t i o n o f t h e c r y s t a l li t e s i n co t t o n i s in c r eas ed

an d th a t o f r em ie i s d ec r eas ed d u e t o in t r a - c r y s t a ll i n e l a t e ra l s w e l l in g u n r es t r a in ed

b y a r e s t r ic t i v e p r im ar y w a l l [ 72] . S t r u c tu ra l r ea l i g n m en t o f ce l l u lo s e c r y s t a l s d o es

t ak e p l ace d u r in g t h e N aO H t r ea tm en t o f f lax f ib r e [73 ] .

Wi th t h e s am e d y es an d co n d i t i o n s o f d y e in g u s ed f o r r em ie , f l ax an d co t t o n ,v a r i a t i o n s ex i s t i n t h e s h ad e p r o d u ced . Al l t h r ee f ib r e s can b e s u cce s s f u l l y m er ce r -

i zed to im p r o v e d y e ex h a u s t i o n an d co lo u r y ie ld , b u t t h e ex t en t o f i n c r eas ed d ep th

o f s h ad e p r o d u ce d o n each t r ea t ed f i b r e w i ll v a r y w i th t h e s p ec i fi c d y e u s ed .

9 .5 M e r c e r i z a t i o n o f B l e n d e d F i b r e F a b r i c s

M er ce r i z a t i o n o f b l en d ed f ab r ic s co n t a in in g p o ly es t e r an d co t t o n i s d o n e t o

im p r o v e t h e l o w lu s t re o f co t t o n a s co m p ar ed t o p o ly es t e r an d a l s o to s ecu r e a m o r e

s o l id d y e in g . F o r s u ch b l en d s t h e m e r ce r i za t i o n p r o c es s i s g en e r a l l y ca r r i ed o u t i n

th e s am e w ay a s 1 00% co t to n , b u t u s in g cau s t i c s o d a o f l e s s e r co n cen t r a t i o n i .e . 4 20

T w a l o n g w i t h p e n e t r a t in g a g e n t. H o t m e r c e r i z a t io n h a s b e e n f o u n d t o g iv e m o r e

u n i f o r m r e s u l ts . U n d e r t h e m e r c e r i z i n g c o n d i t io n s c o t t o n c o m p o n e n t i n t h e b l e n d

u n d e r g o e s p h y s i c a l a n d c h e m i c a l c h a n g e s , w h e r e a s p o l y e s t e r c o m p o n e n t u n d e r -

g o es a t o p o c h em ica l ch an g es , re s u l t i n g i n su r f ace h y d r o ly s i s . T h i s l ead s to a r e -

d u c t i o n i n s t r en g th p r o p o r t i o n a l t o th e w e ig h t lo s s o f t h e p o ly es t e r co m p o n en t . T h e

f ab r ic a f t e r m er ce r i z in g i s n eu t r a l i s ed an d m a d e s l ig h t l y ac id ic (p H 6 ) w i th ace t i c

acid .Gen e r a l l y , th e b l en d s co n t a in in g p o ly es t e r / v i s co s e o r p o ly es t e r / p o ly n o s i c co r n-



2 92 Mer ce r i za t i o n

p o n en t s a r e n o t m er ce r i zed . F ab r i c s co n t a in in g m ix tu r e s o f co t t o n an d r ay o n r e -

q u i r e s p ec i a l p r ecau t io n s a s t h e r eg en e r a t ed f i b r e s , an d i n p a r t i cu l a r t h e v i s co s ef ib re s s h o w a h ig h e r a lk a l i s o lu b i l i ty t h an co t t o n f ib r e s. M ax im u m s w e l l i n g an d

s o lu b i l i ty o f v i s co s e f i b r e s o ccu r a t r o o m t em p er a tu r e f o r N aO H c o n cen t r a t i o n o n

th e o r d e r o f 9 -1 0% b y w e ig h t (1 00 - 11 0 g / l) . Ac tu a l l y , v i s co s e r ay o n w i th s t an d s

th e ac t i o n o f a lk a l i o f m er ce r i z in g s t ren g th , b u t d u r in g w as h in g w i th w a te r , th e

a lk a l i b ec o m es d i l u ted an d a t a co n cen t r a t i o n o f ab o u t 9 - 1 0% (b y w t .) , th e h y d r a t ed

io n p a i rs , 2 0H 2 0 can p en e t r a t e t h e am o r p h o u s a s w e l l a s c ry s t a l l in e r eg io n s , cau s -

in g an u n l im i t ed s w e l l i n g an d t h e f ib r e s a re d eg r ad a t ed . T h e l o s s in s t ren g th o f

v i s co s e f i b r e , t h u s , i s n o t d u r in g m er ce r i za t i o n s t ep , b u t d u r in g t h e w as h in g - o u t

p r o c e s s . T h e f o l l o w i n g a p p r o a c h e s c a n b e a d o p t e d t o m i n i m i s e t h e d e g r a d a t i o n o f

v i s co s e i n th e b l en d s :

( i) A lk a l i sh o u ld b e q u i ck ly r em o v e d f ro m th e f ab ri c a f t e r m er ce r i za t i o n w i th

a g o o d f l o w o f w a te r a t 1 00~ T h e s o lu b i l it y o f v i s co s e i s l e s s m ar k ed a t

h ig h e r t em p er a tu r e .

( ii ) I f p o s s ib l e , h o t m er ce r i za t i o n can a l s o b e ad o p ted to m in im i s e d eg r ad a -

t ion.( ii i) Ad di t ion o f e lec t ro ly te (e .g . NaC1) in the r ins ing ba th d im in ishe s the p ro-

por t ion o f d i s so lved v iscose . Othe r p ro tec t ive agen ts such as sucrose , g lyc-

e r in e e tc . a re a l so r eco m m en d ed .

( iv ) Ad d i t i o n s o f e l ec t r o ly te i n to th e m e r ce r i z in g l i q u o r a re a l so p o s s ib le .

( v) U s e o f K O H o r m i x t u r e o f K O H a n d N a O H i n t h e si m i l a r p r o p o r t io n

(ra t io ) to tha t o f b len de d f ib res in the f abr ics is usefu l . M erc er iz in g w i th

KO H a lo n e can b e d o n e i n a s o lu t i o n o f 5 5 - 60 o T w a t 1 5 -1 8~ w i th d w e l l

t im e o f 90 s ec b u t i s ex p en s iv e .

P o ly n o s i c f i b r e s a r e m o r e s t ab l e t h an t h e o r d in a r y v i s co s e f i b r e s i n a lk a l i n e

m e d i u m a n d t h u s c o t to n / p o l y n o s ic b l e n d e d f a b ri c s c a n b e m e r c e r iz e d w i t h o u t t a k -

in g an y s p ec i a l p r ecau t io n s . Ho w ev er , r i n s in g p r o ces s w i th h o t w a t e r i s a l s o ad v i s -

ab l e . H ig h w e t - m o d u lu s (H W M ) f ib r e i n d u ces a h ig h e r s tr en g th l o s s an d t h u s

m ech a n ica l d eg r ad a t i o n can b e m in im i s ed b y ap p ly in g s u f f ic i en t t en s io n .

9 .6 M e r c e r i z i n g M a c h i n e r i e s

Mer ce r i za t i o n w i th a lk a l i c an b e ca r r i ed o u t i n t h e c lo th (w o v en an d k n i t t ed )f o r m an d i n t h e y a m (h an k ) f or m . M ain ly tw o s y s t em s i .e . ch a in an d r o l l e r m e r ce r -



Mercer iza t ion 293

i z in g ma ch i n es a re d ev e l o p ed fo r merce r i z i n g c l o th i n o p en -w i d t h fo rm. T h e re h as

been a long s tanding suprem acy contes t between cha in type and chainless mercerizer .

One par t i cu lar ly t r i cky prob lem i s reconci l ing the need fo r t ens ion dur ing m ercer -

i z ing wi th the undes i rab i l i ty o f t ens ion in kn i t goods . Yarn m ercer iz ing has , o f

co u r s e , b een co m m erc i a l l y e s t ab li s h ed fo r m an y y ea r s i n t h e m an u fac t u re o f sew -

ing th reads , em bro idery co t tons, and l ace goods . Farmer Nor ton , Be nninger , Mather

an d P l a t t , M ach i n en , Bo b co ck , Bru ck n e r , Bru g man (N e t h e r l an d s ) , Co . P ro . T ex

S.r.1. ( I taly) , Men zel , K usters , G ol ler , Dom ier , Cibi tex, S.r.1. , Kleine we fers , Jaeggl i

an d o t h e r mak e r s h av e d ev e l o p ed n e w t y p es o f mach i n es w i t h t h e a im o f lo w m er -

cer iz ing l iquor p ick-up , good de gree o f me rcer iza t ion , be t t e r f ina l wid th con t ro l ,

i n c reas ed o u t p u t an d co s t r ed u c ti o n . N o w -a -d ay s m erce r i z in g u n i t s a re eq u i p p ed

wi th l iquor co ncen t ra t ion regu la to r , m easur ing un i t, coo l ing un i t , lye recovery un i t,

pur i f i ca t ion un i t , rec ip roca t ing meter ing pump and un i t to d i s so lve caus t i c soda .

Genera l ly a mercer iz ing machine cons i s t s o f four sec t ions which wi l l have d i f fe r -

en t t asks accord ing to the p rocess t echn ique :

i) m ercer iz ing sec t ion : impre gnat ion wi th caus t ic soda;

i i) in te rm ediary squeez ing aggrega te : d iv id ing o f f the m ercer iz in g sec t ionaga inst the s tabi l iz ing sect ion;

u i) s t ab i l iz ing sec t ion : wa ter t rea tm ent and th inn ing do wn co ncen t ra t ion o f

the lye;

iv) interm ediary squeez ing aggrega te : dividing off the stabilizing section against

the wash ing sec tion ;

v) wa sh ing sec t ion : w ash ing -of f the a lka li and neu t ra l i sa t ion ( i f necessary) .

9 .6 .1 C l o t h ( w o v e n ) m e r c e r i z i n g m a c h i n e s

A typ ica l c l ip cha in m ercer iz ing m achine fo r wo ven c lo th is shown in F ig . 9-6 .

9n th i s type o f me rcer iz ing m achine shr inkage i s a llowed in the p r imary s t age o f the

,- _..~._.. ~ . . . ~ . .. . .

i '-" "i'~ '~ t:~" '-0" Centreso C ipC ain ees ~ .~ " ~~ - ~ o: . ~ , ,--- . .. .. . - - - i ~ g d . . , . . . . .~ .. ... .. .. . : . . . . . . . : ~,.

. ]1. .

E2 _ . . . . . . . . . . . . . . . . . . . . . . . . . .

F i g u re 9 -6. C l i p ch a in merce r i z i n g m ach i n e (Co u r t e sy o f M at h e r & P la tt ).




p r o c e s s a n d t e n s i o n i s a p p l i e d i n t h e l a t e r s ta g e t o b r i n g t h e m a t e r i a l t o t h e o r i g i n a l

d i m e n s i o n s . T h e c l o t h is im p r e g n a t e d w i t h c o l d c o n c e n t ra t e d c a u s ti c s o d a s o l u t io nb y p a s s i n g t h r o u g h t w o 3 - b o w l p a d d i n g m a n g l e s . P r e s s u r e o f 1 0 t o 2 5 to n s i s

a p p l i e d a n d m o r e p r e s s u r e i s a p p l ie d t o th e s e c o n d m a n g l e . I n b e t w e e n t h e p a d d i n g

m a n g l e s t h e c l o t h i s p a s s e d o v e r t i m i n g d r u m s t o a l lo w t h o r o u g h a c t i o n o f a lk a li o n

t h e c lo t h . D u e t o h i g h e r s p e e d o f th e s e c o n d m a n g l e o n l y w a r p t e n s i o n c a n b e

a p p l i e d t o t h e f a b r ic a n d a wa r p t e n s i o n i n d i c a t o r i s f i tt e d o n t h e d r u m s . O n l e a v i n g

t h e s e c o n d m a n g l e , t h e c l o t h i s l e d t o a n o p e n s t e n t e r f r a m e f o r a p p l y i n g t e n s i o n

b o t h t h e f i l li n g a n d w a r p d i r e c t i o n . A f t e r t h e c lo t h h a s tr a v e l l e d a b o u t 2 0 f t i n a

s t r e t c h e d c o n d i t i o n a l k a l i i s r i n s e d f r o m t h e f a b r i c b y o v e r f l o w i n g w a t e r f r o m a

s e r ie s o f c as c a d e s . B e n e a t h e a c h o f t h e c as c a d e s , v a c u u m e x t r a c ti o n s l o ts a re

m o u n t e d s o th a t a s t h e r i n s e w a t e r o v e r f l o w s i t is i m m e d i a t e l y v a c u u m e d f r o m t h e

u n d e r s i d e o f th e f a b r ic . T h e w a s h i n g o n t h e s t en t e r ca n b e c a rr i e d o u t in a c o u n t e r

c u r r e n t s y s t e m . T h e r e s id u a l a l k a li c o n c e n t r a t io n s h o u l d n o t b e m o r e t h a n 8 % o n

t h e c l o th . A f t e r l e a v i n g th e s t e n t e r t h e c l o th p a s se s o v e r c o m p e n s a t i n g r o l l e rs wh i c h

r e g u l a t e t h e t en s i o n . T h e c l o th t h e n e n t er s th e r e c u p e r a t o r o r t h e s t e a m i n g b o x

d i v i d e d i n to s e r i e s o f c o m p a r t m e n t s . T h e r e s i d u a l c a u s ti c i n t h e c lo t h i s d i s s o l v e du n d e r t h e a c t i o n o f s t e a m a n d c a u s t i c is c o l le c t e d a t t h e b o t t o m o f e a c h c o m p a r t -

m e n t . O n e m e r g i n g f r o m t h e s t e a m i n g c h a m b e r , th e cl o t h is s q u e e z e d a n d w a s h e d .

T h e s e w a s h i n g u n i t s a re th e f i n al p o r t io n o f t h e m e r c e r i z i n g r a n g e a n d m a y b e a

s e r ie s o f 7 t o 8 w a s h e r s f o l l o w e d b y n e u t r a li s i n g w a s h e r u s i n g e i t h e r s o d i u m b i c a r-

b o n a t e o r a c e t ic a c i d . T h e w h o l e r a n g e i s a b o u t 1 07 f t l o n g wi t h a s t a n d a r d c h a i n

l e n g t h o f 5 0 ft . T h e w i d t h o f th e r a n g e i s 1 4 ft . P r o d u c t i o n o f t h i s m a c h i n e i s a b o u t

5 5 m / m i n .

T h e c h a i n m e r c e r i z i n g m a c h i n e h a s o n e i n h e r e n t d i s a d v a n t a g e . A s t h e fo r c e fo r

k e e p i n g t h e m a t e r i a l u n d e r t e n s i o n a c t s m a i n l y o n t h e o u te r e d g e s a n d t h e l in e o f

f o r c e d i m i n i s h e s t o w a r d s t h e m i d d l e , a g r e a te r e l o n g a t i o n t a k e s p la c e a t th e e d g e s

t h a n i n th e m i d d l e o f t h e f a b r i c ( Fi g . 9 -7 ) . P r i o r to n e e d l i n g u p o n t h e c h a i n s t h e

w a r p d e n s i t y , t h r e a d s p e r c m o v e r t h e w h o l e w i d t h o f th e f a b r ic i s c o n s t a n t, a f te r

s t e n t e r i n g i t i s l e s s at t h e e d g e s t h a n i n t h e m i d d l e . D i f f e r e n t m e a su r e s w e r e t r i e d to

a v o i d t h is c o n s i d e r a b l e d i s a d v a n t a g e b u t n o n e w e r e r e a l ly s u c c e s s f u l. T h e r e f o r e

d e v e l o p m e n t t o o k p la c e f r o m c h a i n m e r c e r i z i n g m a c h i n e s to c h a i n le s s m e r c e r i z i n go r ro l l e r m e r c e r i z i n g m a c h i n e s .




1<

4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . + . 15 6

. . . . . . . . . . . . . . . . . . . . . . .

\

. . .. . .. " . . . . . . . . . . . . . . . . . . . 1

. . . . . . . . . . . . . . . . . . . . . . . . . . . _ j _. . . . . . . . . . . . . . - - 2

Figur e 9 - 7 . D i sa dv a n ta ge s o f c ha in m e r c e r i z ing .

1 . no rm al warp d ens i ty ; 2 . r edu ced de ns i ty ; 3 . no rm al den s i ty ;

4 . d i f fe rence in wa rp den s i ty ; 5 . in f ront of cha in ex pan din g un i t ;

6 . in the cha in exp and ing uni t ; 7 . a f te r the cha in ex pan ding uni t .

T h e l in e d i a g r a m o f a B e n n i n g e r c h a in l e ss m e r c e r iz i n g m a c h i n e i s s h o w n i n

Fig . 9-8 . F ig . 9-9 shows a t r ad i t iona l cha in less merce r iz ing m achin e w i th the ro l le r

' ' 2 " 1 P. ~ , ~ t ~ , - , II p ~ c.,. 6

] Z _ ' ~ . . . . . . . . . . . . .

F i g . 9- 8. C h a i n l e ss m e r c e r i z i n g m a c h i n e ( C o u r t es y o f B e n n i n g e r A G ) .

a r range m ent . In th is sys tem the fabr ic is pre - s t re tched, tens ion i s m a in ta in ed t i l l the

m e r c e r i z ing p r oc e ss a nd a f te r - wa sh ing a r e c om p le te d . The c lo th en te r s the pa d -

d ing se t - up e x a c t ly in a s im i l a r m a nn e r to tha t o f c ha in type . The c lo th a f t er pa d -

d ing wi th m e r c e r i z ing l iquor i s pa s se d th r ough spe c ia l ly c u r ve d a nd spe c i f i c a l ly

d i m e n s i o n e d e x p a n d e r r o l le r s w h i c h m a k e p o s s i b l e a n e v e n e x p a n d i n g e f fe c t o v e r

the who le w id th . The e x pa ns ion de pe nds on the d i a m e te r o f t he r o l le r , the c u r va -

tu r e o f the r o l le r a s we l l as the a ng le o f wa rp . F ig . 9 -10 show s the e xpa n d ing z one




F i g u r e 9 - 1 1 . D r i v e n s y s t e m o f t h e e x p a n d i n g z o n e .1. D i f f e r e n t i a l g e a r u n i t ; 2 . C l o t h t e n s i o n c o n t r o l ;

3 . A c t u a l v a l u e ; 4 . N o m i n a l v a l u e .



M e r c e r i z a t i o n 2 9 7

a r r a n g e m e n t . T h e e x p a n d i n g z o n e c o n s is ts o f a c o m b i n a t i o n o f 5 c u r v e d e x p a n d e r

r o l l e r s a n d 4 d r i v e n c y l i n d r i c a l r o l l e r s . T h e d r i v e s y s t e m i s d r i v e n b y o n e m o t o r

w hi c h d r i v e s t he 4 d r i ve n ro l l e r s v i a d i f f e r e n t i a l ge a r un i t.

W a s h i n g t a k e s p l a c e o n l y a f t er t h e c l o th h a s p a s s e d o v e r f i rs t f e w r o l le r s . N o r -

m a l s h r i n k a g e t a k e s p l a c e in t h e w a s h i n g c o m p a r t m e n t . T h e m a t e r i a l - a t t h e e n tr y

i n t o the m e rc e r i z i n g s e c t i on - i s e xp a nd e d t o i ts o r ig i na l w i d t h a t t he e n t ry i n t o the

w a s h i n g s e c t io n b y th e " m y c o c k " r o l l e r a r r a n g e m e n t . F ig . 9 -1 2 s h o w s t h e a r r a n g e -

F i g u r e 9 - 1 2 . D i f f e r e n t t y p e s o f c h a i n l e s s m e r c e r i z i n g i n s ta l la t io n s .

1 . t r a d i t i ona l r o l l e r a r r a n ge m e n t ;

2 . n e w r o l l e r a r r a n g e m n t o f t h e Z i t t a u e r M a s c h i n e n f a b r i k .

m e n t o f t h e r o l l e r s i n a t r a d i t i o n a l c h a i n l e s s m e r c e r i z i n g m a c h i n e a s w e l l a s t h e

i m p r o v e d a r r a n g e m e n t f o u n d i n t h e m e r c e r i z i n g m a c h i n e o f t he Z i t ta u e r

M a s c h i n e n f a b r i c k . I n t h is t h e r o l le r s a r e n o t s i t u a te d o b l i q u e l y t o o n e a n o t h e r b u t

d i r e c t ly o n e a b o v e t h e o t h e r in p a ir s . T h e m a t e r i a l in th i s a r r a n g e m e n t h a s a l o n g e r

c on t a c t w i t h e a c h o t he r. The c l o t h c on t e n t in t he m e rc e r i z i ng c om pa r t m e n t is l a rge r,

o r a l t e r n a t iv e l y , f o r th e s a m e c l o t h c o n t e n t a s in a t r a d it i o n a l c o m p a r t m e n t , t h i s

a r r a n g e m e n t p e r m i t s a f a r m o r e s p a c e - s a v i n g i n s t a ll a ti o n .

G e n e r a l l y , h o t w a t e r is u s e d f o r w a s h i n g . T h e s t e a m i n g ( r e c u p e r a t o r ) , w a s h i n g

a n d n e u t r a l i s in g s t ep s a r e c a r ri e d o u t i n a s i m i l a r m a n n e r m e n t i o n e d i n t h e c h a i n

t y p e o f m a c h i n e . D e v e l o p m e n t o f n e w h i g h e f fi c ie n c y w a s h i n g u n i ts i n th e m e r c e r -

i zi n g m a c h i n e s h a v e m i n i m i s e d t h e a m o u n t o f w a t er re q u i re d t o a d e q u a t e l y r e m o v e

a l k a l i f r o m t h e p r o c e s s e d f ib r e s [ 7 5, 76 ]. O p e n - w i d t h w a s h i n g s e c t i o n s w i t h v e r ti -

c a l o r h o r i z o n t a l c l o t h r u n w i t h 1 5 - 2 5 m f a b r i c h o l d i n g c a p a c i t y , d r u m w a s h i n g

s e c t i o n w i t h s q u e e z i n g u n i t s a n d " E x t ra c t a " w i t h e ff i c ie n t p r e d e t e r m i n e d w a s h i n ge f f e c t w i t h l o w w a t e r a n d s t e a m c o n s u m p t i o n a r e s o m e o f t h e w a s h i n g u n i ts f re -

q u e n t l y u s e d w i t h m e r c e r i z i n g m a c h i n e s . T h e a d v a n t a g e s o f c h a i n l e s s m e r c e r i z i n g




sys t e m ove r c ha in type a re le s s f loo r spa c e r e qu i r e m e n t a nd m or e p r odu c t ion . I t i s

poss ib l e to p r oc e ss two , o r t h r e e c lo ths supe r im pose d in c ha in le s s m a c h ine to in -c r e a se the ou tpu t .

M e r c e r i z in g a n d c a us t i c i z ing o f c o t ton w ove n f a b r i c s c a n a l so be c a r r i e d ou t i n

ba tc h sys t e m f o r sm a l l a nd m e d ium lo t s [7 7 ] . F igs . 9 - 13 a nd 9 - 14 show the l i ne

F i g u r e 9 -1 4 . M e n z e l " m i n i m e r c e " r a n g e f or m e r c e r i zi n g - c a u st i c t re a tm e n t .

d i a g r a m s o f " S oda t r i c e " ( C ib i te x S . r.1 .) a nd " M in im e r c e " ( M e nz e l ) m e r c e r i z ing a nd

c a us t i c i z ing m a c h ine s . I n the se sys t e m s the f a b r ic a f t e r im p r e gna t ion in a lka l i a nd

e x te ns io n i s wo und on to a r o ll . The c a us t i c soda supp ly t a nk i s m oun te d ove r he a d ,

p r ov id ing g r a v i ty f e e d t6 f il l t he im p r e gna t ion t a nk . Af te r t he t r ough ha s b e e n f il le d




i t i s l i ft ed by hy draul ic p i s tons . At the same t ime the rubber and s tee l ro llers , which

are a r ranged i n a V- fo rmat ion , a re p res sed f rom be low aga ins t t he two squeezerol lers (Fig . 9-13) . The guide ro llers squeeze the good s repea tedly (7 t imes) belo w

the liquor surface . The h igh l iquor fabric in terchange (" sponge im pregn at ion") thus

se t-up p rom otes ex t remely un i fo rm pene t ra ti on o f t he t ex ti le by t he m erce r i z ing

l iquor . Cont inuous contact wi th the guide ro l lers prevents widthwise shr inkage.

The squeeze ro l lers above the impregn at ion t rough w ork wi th a f ixed , driven cent re

ro l ler and two hor izon ta l ly mo vab le squeeze ro l lers . The goods are squeezed of f to

l iquor uptake of about 80%. After the impregnat ion and batching the goods are

ready fo r wash ing -o f f and neu t ra l is a ti on , w ash ing -o f f is a h igh - t empera tu re opera -

t ion. W ater is con t inuou sly spraye d on the fabric during unw inding and s tabi lisat ion

occurs. The repea t ed im me rs ion squeeze o f fp rom otes r ap id r emov a l o f t he caus ti c

soda so lu t ion dur ing w ashing . The adva ntages o f th is sys tem are space saving , bes t

economic ef f ic iency, complete process cont ro l , t ight -s t rand fabr ic guidence wi th

tens ion con t ro l and reduc ed pol lu t ion of envi ronment . T he product iv i ty o f th is type

of mach ine is abou t 3000 m/ h w i th more un i fo rm m erce r iza t i on t han on con t inuous

ranges and a favourable cos t /performance ra t io .Among the va r ious o the r deve lopmen t s K/ i s t e r ' s Ecomerce i s a new sys t em

ut i l i s ing the Flex Nip impregnat ion uni t in which the t rea tment l iquor i s metered

th rough tw in banks o f p ipes w h ich feed a V-shaped t r ea tmen t ba th (F igs . 9 .15 and

9.16). Fabr ic passes ver t ica l ly down w ards a t ope n-w idth throug h the l iquor and

Figure 9-15 . Eco m erce M ercer iz in g m achine (Cou r tesy o f Ki.i 's ters ).




Figure 9-16 . F lex-N ip im preg nat ion un i t (Cou r tesy o f K 't ]s te rs) .

t h e f ab r i c i s s q u eezed o n ex i t fro m t h e b o t t o m o f th e V -s h ap ed l o w l i q u o r cap ac i t y

ba th . "Ec om erce" i s des igned fo r ho t m ercer iza t ion in accordanc e wi th the we t -on-

w e t p ro ces s . T h e g rea t eco l o g i ca l an d eco n o mi c ad v an t ag e o f t h e "E co merce"

process i s tha t the lye c i rcu la t ion con ta ins on ly approx imate ly 10-20 l i t re o f lye .

This cha in less m ercer iz ing sys tem m ain ta ins a cons tan t fabric tens ion in bo th warp

and w ef t d i rec t ions by the use o f d i f fe ren t i a l ly con t ro l led s t re tch ing zone .

K l e i n ew efe r s h as p ro m o t ed t h e ap p l ica t i o n o f r ed u ced p re s s u re t o th e f ab r ic

immedia te ly p r io r to impregnat ion us ing "vacuum cap" un i t [78] to fac i l i t a t e fas t ,

m o re r ap i d an d co m p l e t e s w e l li n g . I n co re merce r i z i n g (F ig . 9 -1 7 ) th e i mp reg n a -

F i g u re 9 -17 . Co re m erce r i z i n g s y s t em w i t h v e r t ica l r eac ti o n s ec ti o n ,

1 V ac u u m h o o d (Co u r t e s y o f K le i n ew efe r s ) .



M ercer iza t ion 3 01

t io n an d r eac t i o n s ec t i o n s co n s t i t u t e t h e m er ce r i z in g co m p ar tm en t . T h e f ab r i c i s

i m p r e g n a t e d w i t h c a u s t ic s o d a s o lu t io n i n t h e im p r e g n a t i n g s e c t i o n w i t h v a c u u m

h o o d . At t h e ex i t s q u eeze r o l l e rs r em o v e ex ce s s l i q u o r f r o m th e fab r ic . M o v in g

o n , th e f ab r i c r u n s t h r o u g h th e r eac t i o n s ec t i o n u n d e r p o s i ti v e g u id en ce i n t h e s am e

w a y a s in a c o n v e n t io n a l m e r c e r i z i n g m a c h i n e .

T h e F a r m e r N o r t o n d u a l p u r p o s e c h a i n m e r c e r i z i n g m a c h i n e c a n b e u s e d f o r

co n v en t io n a l co ld ly e im p r eg n a t io n o r f o r h o t im p r eg n a t io n . H ig h e r im p r eg n a t io n

t e m p e r a t u r e s a r e a l w a y s f o l l o w e d b y c o o l i n g s e c t i o n t o e n s u r e m a x i m u m f i b r e

s w e l l in g . F a r m e r N o r t o n ( U . K . ) h a s a ls o d e v e l o p e d a " B a b y M e r c e r iz e r " w h e r e

th e fab r i c p as s es b o th d i r ec t i o n t h r o u g h th e m ach in e . Ap a r t fr o m th e lo w l ev e l

i n v es tm en t c h a r ac t e r , t h is m ac h in e i s u s e f u l f o r s m a l l s ca l e p r o ces s o r s .

T h e G o l l a r Pe r f e c ta c h a i n m e r c e r i z e r u s es t w o l o w v o l u m e i m p r e g n a t i o n u n i ts

w i t h l o w t e n s io n f a br ic g u i d in g . T h e G o l l a r O p t im a M o d e l M M c h a i n le s s m e r c e r-

i z in g ran g e f o r s i n g l e ru n t r ea tm en t o f w o v en an d k n i t t ed f ab r ic s , f r o m p i l e o r

l a r g e - d i am e te r s b a t ch , m ay b e o p t io n a l l y u s ed f o r im p r eg n a t io n w i th cau s t i c s o d a

d r y - o n - w e t o r w e t - o n - w e t .

B e n n i n g e r ' s D i m e n s a m e r c e r i z a t i o n r a n g e ( F i g . 9 - 1 8 ) i s a c o m b i n a t i o n o f

F i g u r e 9 - 1 8. D i m e n s a m e r c e r i z i n g m a c h i n e : c l o th r u n d ia g r a m . 1. i m p r e g n a t i n g

zon e; 2 . coo l ing and r eac t ion zone ; 3 . s ten ter f ram e ; 4 . s tab i liz ing zone ; 5 . wa sh ingan d n eu t r a l i s i n g zo n e .

ch a in l e s s an d ch a in t y p e m er ce r i z in g m ac h in e . T h e f ab r ic i s f ir s t im p r eg n a t ed w i th

h o t m e r c e r i z i n g l y e in a v e r y s h o r t in t e n s iv e i m p r e g n a t i o n c o m p a r t m e n t f o l lo w e d

b y a co o l in g an d r eac t i o n zo n e . In t h is a r ea f ab ri c g u id en c e i s o n th e ch a in l e s s

p r in c ip l e . T h i s i s f o l lo w ed b y a p in s t en te r s ec t i o n o r st ab i l is i n g zo n e i n w h ich h o t

w ea k lye is in t roduc ed in to the f abric us ing the cha in p r inc ip le . Ul t ima te s tab i li sa tion

i s o b t a in ed u s in g a co n v en t io n a l , h ig h ly e f f ec t i v e s t ab i l i s i n g co m p ar tm en t w i thch a in l e s s g u id en ce . T h e f in a l sec t i o n co m p r i s e s a h ig h e f fi c i en cy w as h in g an d




ne u t r a l i s ing z one c ons i s t ing o f Ex t r a c t a c om p a r tm e n t s . S a v ing on s tr ong lye , wa -

t e r a nd s t e a m o f a r ound 30 % a nd sho r t e r dow n t im e s a r e cl a im e d .Ap p l i c a t ion o f f oa m e d a lka li l i quor on the c lo th c a n p r odu c e one s ide d m e r c e r -

iza t ion and d i f fe rent ia l dye ing [79] .

S om e innov a t ive ope n wid th wa sh in g un i t s a r e de ve lope d in wh ic h s t e a m , wa te r

a nd a i r a r e p r o je c t e d on to bo th s ide s o f fa b r i c in a ny de s i r e d c om bina t ion to ge ne r -

a t e tu r bu la n c e a nd in t e ns ive w a sh in g o f the m e r c e r i z e d f a b r i c s.

9 .6 .2 Y a r n m e r c e r i zi n g m a c h i n e s

M a n y m a c h i n e s f o r m e r c e r i z i n g o f co t to n y a r n i n th e f o r m o f h a n k a re d e v e l -

o p e d . T h e y a m m e r c e r i z i n g m a c h i n e u s u a l l y a v a i la b l e m a y b e s i n g le s id e d o r

doub le s ide d w i th a bou t 5 to 10 kg pe r ba tc h pe r pa i r o f r o l le r s . A lm os t a l l t he ya m

m e r c e r i z in g m a c h ine s ha ve s im i l a r ity in de s ign . M a the r & P la t t, B e r t sh inge r ,

K le ine w e f e r , Noubo ld , J a e gg l i a nd o the r s ar e we l l known m a ke r s o f ya m m e r c e r i z -

i n g m a c h i n e s . U s e f u l s u m m e r i e s o f t h e s ta te o f th e a r t o f y a r n m e r c e r iz i n g h a v e

b e e n p r e s e n t e d [ 8 0- 82 ] . A ty p i c a l t w o s i d e d y a m m e r c e r i z in g m a c h i n e ( d o u b l e

a r m type ) i s shown in F igs . 9 -19 a nd 9 -20 . The m a c h ine i s p r ov ide d w i th pa i r s o f

F i g u r e 9 - 1 9. Y a m m e r c e r i z i n g m a c h i n e ( C o u r t e sy o f M a t h e r & P l a tt ).

ro l le r s a nd on e ro l le r is f ixed and the o the r i s m ov able (B) (Fig . 9 -20) . Ya rn i s la id

on the r o l l e r s a nd the n c a us t i c soda so lu t ion o f 25% s t r e ng th at 20~ i s a pp l i e d by

r a i s ing the t r ough , F . The r o l l e r s a r e c a use d to r o t a te a nd the ya r n i s a llow e d tosh r ink du r ing im p r e gna t ion p r oc e ss to e nsu r e pe ne t ra t ion o f a lka l i. I t i s a r r a nge d to

br ing the ro l le r s som ew hat c lose r toge the r whi le they s t il l cont inue ro tat ing . Squeez-




(a)

, 9 i ~ . ~ .

r [ - - - ,

(b) (c)

F ig u r e 9 - 2 0 . L in e d i ag r am o f y a r n o n r o l l e rs ( a ) w a t e r t r o u g h o n t r o l l y ;

(b ) in s t r e tche d s ta te ; (c ) in s lack s ta te .A - S t a t io n a r y r o l le r

B - M o v a b l e ro l l e r

C - Sq u eez in g r o l l e r

D - Y a r n in h a n k fo r m

E - S p u rt p i pe

F - C a u s t ic so d a t r o u g h

G - W a t e r t ro u g h o n t ro l ly

H - R a i l

i n g r o l l e r (C) ab o v e t h e f ix ed r o l l e r a l s o a s s is t s p en e t r a t i o n o f a lk a l i. T h e y am i s

t h e n s t r e t c h e d d u r i n g w h i c h t h e r o l l e r s a r e m a d e t o m o v e a w a y f r o m e a c h o t h e r

s t ead i ly t h u s ex t en d in g t h e l en g th o f t h e s k i en s an d s t r e t ch in g t h e y am to ab o u t i ts

o r ig in a l l en g th . T h e e x ces s a lk a l i i s s q u eez ed o u t . T h e a lk a l i t r o u g h (F ) t h en g o es

d o w n a n d t h e w a t e r tr o u g h ( G ) is b r o u g h t i n to p o s it io n . T h e y a m i s w a s h e d b y

s p r ay in g h o t an d co ld w a te r t h r o u g h s p u r t p ip e an d t h e y am i s s t i l l u n d e r t en s io n

a n d i s s q u e e z e d . D u r i n g m e r c e r i z i n g a n d w a s h i n g t h e d i r e c ti o n o f t h e r o t a ti o n o f

r o l l e r s an d t h u s t h e s k i en s a r e p e r io d i ca l l y r ev e r s ed w h ich en s u r e s ev en p en e t r a -

t io n . F in a l l y , th e s u p p o r t i n g a r m s g o d o w n , t en s io n i s r e l ea s ed , r o l le r s co m e c lo s e r

to g e th e r , s q u eez in g r o l l e r s a r e l i f t ed u p , h an k s a r e r em o v ed f r o m th e r o l l e r s an d

t h e n n e u t r a l i se d w i t h a ci d a n d a g a i n w a s h e d i n o t h e r a p p a r a tu s . T h e c o m p l e t ecy c l e t ak es 5 m in o u t o f w h ich a lk a l i t r ea tm e n t l a s t s fo r 2 .5 m in . T h e w h o le cy c l e

o c c u r s in o n e c o m p l e t e re v o l u t i o n o f t h e c a m s h af t. M a c h i n e r y d e v e l o p m e n t s o f

in te r e s t i n c lu d e t h e co n e - to -co n e co n t in u o u s y am m e r ce r iz in g m a ch in e f ro m J aeg g l i

w i th h ig h ly d ev e lo p ed au to m a t i c co n t r o l [ 83 ] . Var io u s s t u d i e s h av e b een ca r r i ed

o u t to ex am in e t h e p o t en t i a l f o r m er ce r i ze d r o to r y a r n s [84 , 85 ].

9 .6.3 K n i t goods m ercer iz ing mach ine s

T h e t r ad i t i o n a l m ach in es u s ed f o r m er ce r i z in g w o v en f ab r i c s a r e i n ad eq u a t e t o

t r ea t c i r cu lar kn i t f abr ics . O w ing to kn i t s t ruc tu re , such f abr ics a re eas i ly deform ed ,

d i s to r t ed an d ex t en d ed o n s t r e t ch in g d u r in g m er ce r i za t i o n an d w a s h in g . T h e s e d i s-




to r ti ons bec om e p erma nen t and have adverse e f fec t on the e l ast ic p roper t i e s o f t he

fabr ic s t ructure [86, 87] . T he exis t ing chain less merce r iz ing machines can be modi -

f ied to su i t the kni t goods e i ther by ins ta l l ing tens ion co nt ro l l ing device [88, 89] or

by p roces s ing be tween conveyer be l t s [90, 91 ] . How ever , t he ma in d i s advan t ages

o f open wid th kn i t goods merce r i z ing a re edge c reases o f t he f la t tened t ube and

var ia t ion in severa l character i s ti cs f rom e dge to cent re . To e l iminate edge creas ing

pro blem ai r is in t roduced in to the fabr ic by m eans of j e t s to bal loon the tube [92]

and severa l ma nufac tu re r s have p roduc ed m ach ines fo r kn i t goods merce r i za t i on .

A typ i ca l Do m ier con t inuous m erce r i z ing range fo r t ubu la r kn i t goods is shown

in Fig . 9-21 . Fig . 9-22 shows the l ine d iagram of s im i lar Sperotto Rim ar Kn i t goods

F igure 9 -22 . S pero t to R imar K n i t goods merce r i z ing range .



Mercerizat ion 305

m ercer iz ing range . Other m achine ry ma nufac turers o f fe r ing equ ipm ent fo r tubu lar

fabr ic mercer iz ing inc lude Jaegg l i [93] , Caber [94] , Pegg-Whi teby [95 ,96] e tc .Do r n ie r 's t u b u la r m er ce r i z in g r an g e co n s i s t s o f a f l a t tu b u la r im p r eg n a t io n zo n e

fo l lowed by open ing of the fabr ic us ing a c i rcu la r expander wi th ro l l ing f r ic t ion

an d p r e ssu re co m p en sa t io n . Th u s a h ig h e r sp r ead in g t en s io n can b e ach iev ed w i th

a lm ost constan t trac t ion fo rce , i.e . long i tud ina l tens ion . M otor ised ad jus tm ent o f

c i rcu la r and f la t tube e xpand ers d ras t ica l ly decrease the se t t ing up t im es , and the

wa te r u sed in rin s in g i s r ecy c led an d p assed th r o u g h a h ea t r eco v e r y sy s t em .

Th e sp e r o tto R im ar MT - 1 5 tu b u la r co t to n k n i t t ed f ab r ic m er ce r i ze r co n s is t s o f

th ree un i ts , an impreg nat ion / reac t ion tank , a s tab i l i sa t ion and reduc t ion tow er and a

wa sh ing and r ins ing tower . To ach ieve tens ion in the w id th s tee l sp readers (ca l led

c igars) a re necessary , these be ing p laced ins ide the c i rcu la r kn i t f abr ic enab l ing

s t re tch ing d ur ing passage o f the fabr ic bo th in the f i r s t phases o f ho t wash ing and in

the fo l lowing co o l ing phases . In case o f MC S m achine th is f rame is fla t and hor i -

zon ta l , bu t the o ther man ufac turers p rodu ce ver t ica l f rames o f tubu lar des ign .

Kni t goods mercer iza t ion can a lso be done in ba tches by r ins ing the kn i t ted

fabr ics a f te r impreg nat ion and w ind ing on to a per fo ra ted beam [97] o r by car ry ingout the s tab i l i sa t ion by w ater sp ray ing du r ing ba tch ing a f te r impregn at ion [98, 99].

Based o n th e tu b u la r f ab ri c m er ce r i z in g m ach in e , Do m ie r , Gm b H, h as d ev e l -

o p ed a co m b in ab le m er ce r i z in g an d b leach in g co n cep t f o r t u b u la r wa r p k n i t t ed

f ab ri c s. Th e co m b in ed m er ce r i z in g /b leach in g m ach in e ( F ig . 9 - 2 3 ) co m p r i se s im -

F ig u r e 9 -2 3 . Co m b in ed m er ce r i z in g /b leach in g m ach in e f o r

tu b u la r wa r p k n i t t ed f ab r i c s ( Co u r t e sy o f Do r n ie r , Gm b H) .pregna t ing , reac t ion and sco ur ing sec t ions in the mercer iz ing un i t , and i s com ple-




m e n t e d b y a h e a t i n g a n d d w e l l z o n e f o r p e r o x i d e b l e a c h i n g . A c o m b i n e d a f t e r-

w a s h i n g s e c t io n c a n b e i n t e g r a t e d , e n a b l i n g f l u o r e s c e n t b r i g h t e n e r s t o b e a p p l i e d ,

i n c l u d i n g a n e u t r a l is i n g b a t h a n d t r e a t m e n t t r o u g h l o c a t e d a f te r th e s c o u r i n g u n i t.

T h e m e t e r i n g c y c l e s a r e c o n t r o l l e d , a u t o m a t i c a l l y r e g u l a t e d a n d p a r t i a l l y m o n i -

t o r e d .

9 .7 H o t M e r e e r i z a t i o n

S i n c e t h e b e g i n n i n g o f th e s i x t ie s , m e r c e r i z a t i o n w i t h h o t c a u s t ic s o d a a t a te m -

p e r a t u r e b e t w e e n 6 0- 7 0~ h a s b e c o m e k n o w n a s h o t m e r c e r i z a t io n . I n c l a s si c a l

c o l d m e r c e r i z i n g , p r o c e s s i n g t a k e s p l a c e a t t e m p e r a t u r e s o f 1 5 t o 1 8 ~ w i t h 3 1 to

3 5 % c a u s t i c s o d a s o l u t i o n w i t h a d w e l l i n g p e r i o d o f a b o u t 5 0 s e c o n d s . A t th a t

r a ng e c o t t on s w e l l s be s t bu t a l so f a s t e st . The f a s t s w e l l i ng inc r e a s e s t he ou t e r e dge

de n s i t y o f the f i b r e a l s o r a t he r s w i f tl y . Th e v i s c os i t y o f the c a us t i c s o l u t i on i s a ls o

s u c h t h a t t h e p e n e t r a t i o n i n to t h e g r e y f a b r ic b e c o m e s e v e n m o r e d i ff ic u l t. T h e s e

r e s u l t i n p o o r m e r c e r i z i n g o f t h e c o r e a n d l a c k o f u n i f o r m i t y a s t h e r e a c t i o n i s

r e s t r i c te d m a i n l y t o th e s u r f a c e o f t h e y a m o r fa b r ic . T o i n c r e a s e t h e p e n e t r a t i o n

i n t o the f i b r e a l ka l i s t a b l e w e t t i ng a ge n t s a r e ne c e s s a ry a nd a r e e xpe ns i ve . I n a dd i -

t i on , the e f f l ue n t l oa d i s c on s i de ra b l e a nd e c o l o g i c a l l y c r i t ic a l .I n h o t m e r c e r i z a t i o n p r o c e s s , w i t h c a u s ti c s o d a a t 6 0 -7 0 ~ t h e c o t to n s w e l ls

m ore s l ow l y . Th e ou t e r e dge de ns i t y o f the c o t t on f i b r e is no t i nc r e a s e d a s f a st a s i n

c o l d m e r c e r i z i n g . A t 6 0 -7 0 ~ t h e v i s c o s i t y i s c o n s i d e r a b l y lo w . T h u s t h e p e n e t r a -

t io n o f a l k a li i s e x t r e m e l y r a p i d w i t h i m p r o v e d c o r e m e r c e r i z a ti o n a n d c o n s e q u e n t l y

r e s u l t s in b e t te r u n i f o r m i t y o f a l k a li tr e a t m e n t . D u e t o h ig h e r t e m p e r a t u r e a n d

h i g h e r d i f f u s i o n i n to t h e c o r e t h e d w e l l ti m e o f th e m a t e r i a l in t h e m e r c e r i z i n g

s e c t i on c a n be r e duc e d f rom 50 s e c ( c o l d ) t o 20 s e c ( ho t ) . I n o t he r w ords , t he

m e r c e r i z i n g i n s ta l la t io n f o r th e s a m e p r o d u c t i o n s p e e d i s s h o r te r t h a n t h e o n e b a s e d

on c o l d m e rc e r i z i ng . F i g . 9 -24 s how s t he in t e r r e l a ti ons be t w e e n t he ne c e s s a ry dw e l l

t i m e a n d t h e t e m p e r a t u r e o f t h e ly e . C o l d m e r c e r i z i n g r e q u i r e s a b o u t 55 s e c t o

r e a c h a n o m i n a l c o n c e n t r a t i o n o f 3 00 g /1 o n t h e m a t e r ia l . H o t m e r c e r i z i n g a t 6 0 -

7 0 ~ a c h i e ve s t he s a me po s s i b l e e f f e c t a l r e a dy in 20 s e c onds .

I n h o t m e r c e r i z a t i o n f a b ri c i s ei t h e r p a d d e d t h r o u g h h o t c a u s t ic s o l u ti o n o r a t

a m b i e n t t e m p e r a t u r e a n d t h e n p a s s e d t h r o u g h s t e a m e r w h e r e t h e fa b r ic i s s t e a m e d .

T h e p r o c e s s s e q u e n c e o f t w o s te p h o t m e r c e r i z a t i o n i s a s fo l l o w s :




"-~ 2

E I /" /" .-- "

9 / E /= .......... 5: ./ ,.: ,~ "

o : il.:('/6

Dw el l t im e in cau s t i c s o d a ( s ec )

F ig u r e 9 - 2 4 . N a O H co n c en t r a t i o n i n th e tex t i l e f ab ri c i n

r e l a t i o n t o d w e l l t im e in t h e l y e an d l y e t em p er a tu r e .

1 N a O H i n m a t e r i a l ( g / l) ; 2 n o m i n a l c o n c e n t r a t i o n

( a p p ro x . 3 0 0 g/1 N a O H ) ; 3 " F l e x n i p " a d d i ti o n

m erc er i z in g 60 . .. . 70~ ; 4 ho t m erc erz ing 60 . .. . 70~ ;

5 co ld m er c e r z in g 1 0 .... 1 5 ~ ; 6 d w e l l t im e in N aO H.

i ) Sa tu r a t i o n o f co t t o n m a te r i a l w i th s o d iu m h y d r o x id e s o lu t i o n o f m er ce r -

i z in g s t re n g t h p r e fe r a b l y u n d e r r e la x e d c o n d i ti o n a t te m p e r a t u r e b e t w e e n

60~ an d b o i l i n g p o in t w i th an im p r eg n a t io n t im e r an g in g f r o m 4 t o 60sec.

i i) Co n t r o l l ed h o t s t r e t ch in g f o l l o w in g th e s a tu r a ti o n . T h e m a te r i a l b e in g

s t r e t ch ed 2 - 2 0% o f it s o r i g in a l d im en s io n s .

i ii ) Co o l in g th e s tr e t ch ed m a te r i a l t o a t em p er a tu r e le s s t h an 2 5 ~ w h ich co m -

p le t e s t h e s w e l l in g e f fec t .

i v ) T e n s io n co n t r o l l ed w as h in g t o N aO H s o lu t i o n o f 6% ( s t ab i li s a t io n ) .

v ) F i n a l w a s h i n g o r n e u t r a l is a t i o n u n d e r n o r m a l c o n d i t i o n w i t h o u t te n s i o n

b e in g a p p l i ed t o t h e f ab r i c.

A n o t h e r p o s s ib l e m e t h o d o f h o t m e r c e r i z a t io n c o n s is t s o f w e t - in - w e t i m p r e g n a -

t i o n o f f ab r i c im m ed ia t e ly a f t e r w as h in g a t 95~ an d a s u b s eq u en t h o t s q u ee z in g

w i th h ig h s p eed s t eam in j ec t ed . T h e h ea t ed f ab ri c is t h en im p r eg n a t ed w i th cau st i c

so lu t io n a t 30~ in the f i r s t s tep and 20~ in the second s tep . Th ese o f fer the

s t ab i li s a t io n . Seq u en ce i s n o r m a l ly ca r r i ed o u t u n d e r t en s io n co n t r o l l ed co n d i t i o n .

T h e v a r io u s f ac to r s ch an g in g t h e p r o p e r t i e s o f co t t o n d u e t o h o t m er ce r i za t i o n

a r e s li g h t l y d i ff e r en t f r o m th a t o f co n v en t io n a l m e r ce r i za ti o n . T h e d eg r ee o f s w e l l -i n g o f i n d iv id u a l f i b re i s l o w er a t h ig h e r t em p er a tu r e s [ 1 00] a s th e p r o ce s s i s an



30 8 Me rc e r i z a t i on

e xo t he rm i c one . The c onv e r s i on o f t he c rys ta l l ine s t ruc t u r e f rom C e l l u l os e I t o

C e l l u l os e I I i s r e t a rde d a t h i ghe r t e mpe ra t u r e a nd r e ve a l s a s k i n - c o re a ppe a ra nc e[ 101 ] . M e rc e r i z i ng a t e l e va t e d t e m pe ra t u r e s c a n l e a d to i mp rove m e n t s i n l u s tr e

a n d s h r i n k a g e , h a s n o a d v e r s e e f f ec t o n s t re n g t h , a n d u n d e r c e r ta i n r e c o m m e n d e d

c ond i t i ons , c a n r e s u l t i n a s o f t e r ha nd l e [ 10 2-10 5] . H ow e ve r , t he i m pro ve m e n t i n

l us t r e i s c on t r a d i c t o ry w h i c h m a y be due t o t he fa c t t ha t t he doub l e t r e a t m e n t du r -

i ng ho t me rc e r i z a t i on p roduc e s a d i f f e re n t r e s pons e c om pa re d w i t h t ha t o f the s i ng l e

s t a ge p roc e s s in c o l d me rc e r i z a t i on . Te m pe ra t u r e s up t o 45~ c a n be us e d w i t hou t

a ny d e t e r i o r a t i on o f l u s tr e [ 10 6] , bu t on t he o t he r ha nd no s ubs t a n t ia l i m prov e m e n t

i n lu s t r e i s f ound a s a r e s u l t o f doub l e m e rc e r i z a t i on [ 10 7] .

T h e f o l l o w i n g a d v a n t a g e s c a n b e d e t ai le d f o r t h e h o t m e r c e r i z in g p r o c e s s :

i ) D u e t o h i gh e r a nd r a p i d pe ne t r a t i on o f a l ka li , l e ve l a nd un i fo rm m e rc e r -

i z a t i on c a n be ob t a i ne d w i t h l e s s e r c on t a c t t i me r e s u l t i ng i n g r e a t e r p ro -

d u c t i v it y w i t h m o r e c o m p a c t u n it .

i i) A t h i gh e r t e mp e ra t u r e ( a bou t 100 ~ t he s h r i nka ge i s ne a r l y ha l f a s c om -

pa re d t o c onve n t i ona l m e rc e r i z a t i on a nd the s h r i nka ge doe s no t va ry w i t h

dw e l l t ime .i ii ) The ne c e s s a ry a nd e xpe ns i ve a l ka li r e s i s ta n t w e t t i ng a ge n t s ne e de d i n c o l d

m e r c e r i z a t io n a r e n o t n e c e s s a r y f o r t h e h o t m e r c e r i z i n g p r o c e s s . P r o d u c -

t i on c os t s ar e r e du c e d a nd the e nv i ronm e n t l oa d i s l ow e re d .

iv) In hot merce r iza t ion the f reed reac t ive hea t is used to ra i se the t em pera ture

of the lye to abo ut 40~ Th e fur the r inc rease in hea t to abo ut 60-70~ i s

d o n e i n a m o d e r a t e l y p r i c e d h e a t e x c h a n g e r .

v ) The f i b r e a nd fa b r i c s t ruc tu r e be c om e mo re p l i a b l e a nd l e ss e l a s ti c .

v i ) H i g he r t e ns i le s t r e ng t hs a r e ob t a i ne d du e t o g r e a t e r de g re e o f s t r e tc h a nd

m odi f i c a t i on o f c e l l u l os e w h i l e s a t u r a t e d w i t h ho t c a us t ic s oda s o l u ti on .

Th e s e l e a d t o a g r e a t e r o r i e n t a t ion o f m o l e c u l a r s t r uc tu r e a nd i nc r e a s e d

c ohe s i on be t w e e n f i b r e s .

v i i) H o t m e rc e r i z e d f a b r i c s ha ve be t t e r w e t c r e a s e r e c ov e ry t ha n c onve n t i on -

a l ly m ercer ized fabr ics . I t indu ces easy ca re fin i sh ing charac te r i s t ic s . Ho t

m e rc e r i z e d f a b r i cs a r e f la t te r a nd l e ss c rum pl e d w h e n d r i p d r i ed .

v i ii ) H o t me rc e r i z e d c o t t on f a b r ic g i ve s un i fo rm a pp l i c a t ion o f dye s . Thou ght he t o ta l up t a ke i s be t t e r, bu t t he c o l ou r y i e l d i s l e ss p rono unc e d t ha n c on-




v en t io n a l m er ce r i ze d co t t o n . T h e co lo u r y i e ld d ec r eas es a s t h e t em p er a -

tu r e o f m e r ce r i z in g t r ea tm en t i n c r eas es [ 1 08 ].i x ) T h e c o m b i n e d m e r c e r i z i n g a n d d e s i z i n g , a n d m e r c e r i z i n g a n d s c o u r i n g

p r o ces s es m in im i s e t h e en e r g y co n s e r v a t i o n an d can l ead t o co s t s av in g .

In co m b in ed p r o ces s es a s t eam in g s t ep is in s e r t ed b e tw een h o t a lk a l i s a tu -

ra t ion an d s tab i l i sa t ion [ 109] . The s team ing t ime i s abou t 10 m in a t a tm o-

s p h e r i c p r e s s u r e an d ab o u t 5 s ec u n d e r p r e s s u r e a t 1 3 0 - 1 4 0~

x ) Ho t m er ce r i z in g t ech n iq u e a l so r ed u ce s t h e i n v en to r y an d p o l lu t i o n p r o b -

lem.

9 .8 L i q u i d A m m o n i a M e r c e r i z a ti o n

So m e tw en ty y ea r s ag o i t w as f o u n d in s y s t em a t i c r e s ea r ch w o r k t h a t a t r ea t -

m en t o f co t t o n f i b r e w i th l i q u id am m o n ia p r o d u ces e f f ec t s im i l a r t o t h a t o b t a in ed

w i t h c a u s t ic s o d a . L i q u i d a m m o n i a t r e a t m e n t w a s f i rs t d e v e l o p e d b y t h e E n g l is h

f i rm C o a t s i n t h e m id - 1 960s . Co a t s d ev e lo p ed a p r o ces s w i th w h ich i t w a s p o s -

s ib l e t o t r ea t co t t o n y a r n i n a co n t in u o u s m an n e r an d t h e f i r m P la t t Saco Lo w e l l

L td . , Ac c r in g to n , E n g lan d acq u i r ed t h e w o r ld w id e l i cen ce f o r t h is p r o ces s ca l l ed

" P r o g r a d e " . T h e f i rm C l u e tt , P e a b o d y & C o . , k n o w n f o r i ts p r o c e s s o f c o m p r e s -s iv e s h r in k in g (San f o r i s in g ) , h a s i n 1 973 r eg i s t e r ed tw o t r ad e m a r k s : "D u r a l i ze d ' ' ,

n a m e f o r a m a t e r i a l t r e a t e d w i t h l i q u i d a m m o n i a a n d " S a n f o r - S e t " , n a m e f o r a

m a t e r i a l t r e a te d w i t h li q u id a m m o n i a a s w e l l a s b y c o m p r e s s i v e s h r i n k a g e , s y s t e m

C l u e tt . T h e l i q u i d a m m o n i a t r e a tm e n t i s w i d e l y a c c e p t e d f o r y a m s u s e d i n s e w i n g

th r ead s an d f o r s p ec i a l f ab r ic s s u ch a s d en im s , co r d u r o y s , ch am b ay s , p i l l o w m a te -

r i a l, m a te r i a l s m ad e o f ce l lu lo s e , l i n en , j u t e an d m ix tu r e s o f ce ll u lo s e w i th p o ly es -

t e r o r n y lo n .

Am o n g v a r io u s am in es , t h e l i q u id am m o n ia a p p ea r s t o b e u n iq u e i n it s s w e l l i n g

ac t i o n o n ce l l u lo s e a n d i ts e f fec t o n c r y s ta l s t ru c tu r e . An h y d r o u s l i q u id am m o n ia ,

b e i n g s m a l l e r m o l e c u l e , p e n e t r a t e s c e l l u lo s e v e r y r a p id l y a n d c o m p l e x e s w i t h h y -

d r o x y l g r o u p s o f ce l l u lo s e a f t e r b r eak in g h y d r o g en b o n d s i n c r y s ta l l in e r eg io n s an d

in c r eas es d i s t an ce b e tw een ce l l u lo s e ch a in i n c r y s ta l l i te s [ 1 09 -1 1 5 ] .

T h e "P r o g r ad e" p r o ces s req u i r e s th e ad d i ti o n o f s e l ec ted am in es t o im p r o v e t h e

o r ig in a l am m o n ia s y s t em . In t h i s p r o ces s (F ig . 9 -2 5 ) y am i s t r ea t ed i n l i q u id am -

m o n ia a t i ts b o i l i n g p o in t ( - 3 3 ~ o r - 2 8 ~ f o r l e s s t h an a s eco n d , t h en s u b s eq u en ti m m e r s i o n o f y a m u n d e r t e n s i o n i n h o t w a t e r f o r a b o u t 0 .1 s e c to p r o d u c e a 4 0 %



310 M e r c e r i z a t ion

S upp ly

b o b b i n

Te ns ion

contro l

t

Uptake

b o b b i n

H o t w a t e r

ba th ~ 20 0 ~L i q u i d NH 3

b a t h - 28~

F i g u r e 9- 2 5 . D i a g r a m o f t h e " P r o g r a d e " p r o c e s s [ 1 1 6] .

inc r e a se in t e ns i le s t r eng th , im pr ov e d lu s t re e t c . In th i s p r oc e ss the ya r n a f t e r a m -

m o n i a t r e a t m e n t i s s tr e tc h e d a n d s u b s e q u e n t l y a m m o n i a i s r e m o v e d b y h o t w a t e r

wa sh ing .

" S a n f o r s e t " r e p r e se n t s a c o m b i n a t io n o f e x c l u s iv e l iq u i d a m m o n i a p ro c e s s i n g

a nd c on t r o l l e d c om pr e ss ive sh r inka ge to p r ov ide no i r on c ha r a c te r i s t i c s w i thou t

s t r e ng th lo s s on c o t ton de n im s , p lus a n un usua l ly so f t a nd supp le ha nd le . The in -

s t a l l a t ion f o r a m m onia t r e a tm e n t on wove n a nd kn i t t e d f a b r i c i s shown in F ig .

9 - 26 . F ig . 9 - 27 show s the fund a m e n ta l c on s t r uc t ion o f suc h a n in s t a ll a t ion f o r the

a m m on ia p r oc e ss . A f t e r t he e n te r ing p r oc e ss ( 1 ) the m a te r i a l pa s se s ove r f ive p r e -

d r y ing c y l inde r s ( 2 ) a nd the n th r oug h a c oo l ing s t a t ion (3 ). The d r y ing c y l inde r s

r e d u c e t h e m o i s t u r e c o n t e n t o f t h e m a t e ri a l t o b e l o w t h e n o r m a l h u m i d i ty , w h i l st

the c oo l ing s t a t ion i t is be ing c oo le d . Th e m a te r i a l t he n pa s se s th r ough a loc k ( 4 )

in to the a c tua l t r e a tm e n t c ha m be r ( 5 ) wh e r e i t i s im p r e gna te d w i th l iqu id a m m onia

in a t r oug h ( 6 ). F ina l ly i t i s sque e z e d o f f in a pa dd e r w h ic h c a n be d e te r m ine d by

loop ing ( 7) . The a m m onia i s d r ive n o f f i n two f e lt c a le nde r s . I n th i s he a t t r e a tm e n ts o m e 9 0 - 9 5 % o f t h e a m m o n i a i s r e m o v e d . T h e r e st , w h i c h i s c h e m i c a l l y b o u n d t o




F i g u r e 9 -2 7 . S a n f o r - s e t t r e a t m e n t r a n g e ( C o u r t e s y o f M o n f o r t s , G e r m a n y ) .

t h e c e ll u l o s e i s r e m o v e d i n a s t e a m i n g c o m p a r t m e n t ( 9 ) c o n s i s t i n g o f a p r e - d w e l l -

i n g z o n e ( 1 0 ) a n d a s t e a m i n g z o n e (1 1 ). T h e e n t e r i n g a n d e x i t e n d s o f t h e s t e a m i n g

c o m p a r t m e n t a r e a g a i n s e a l e d b y l o c k s ( 1 2 ) . A n a f t e r d w e l l i n g z o n e ( 1 3 ) a n d t h e

t a k e - o f f d e v i c e ( 1 4 ) c o m p l e t e t h e i n st a ll a ti o n . T h e t r e a t m e n t c h a m b e r i s k e p t u n d e r

s li g h t v a c u u m t o p r e v e n t a m m o n i a g a s f r o m e s c a p in g . T h e e v a p o r a t e d a m m o n i a i s

l e d to a r e c o v e r y u n i t w h e r e i t i s c o m p r e s s e d , c o o l e d a n d l i q u i d i z e d , t o b e l e d t o as t o r a g e ta n k f o r l a te r p e r u s a l. T h e c h e m i c a l l y b o u n d a m m o n i a i s r e m o v e d f r o m t h e

m a t e r i a l s e p e r a t e l y . I t is p o s s i b l e t o d i s so l v e i t i n w a t e r a n d r e u s e i t as a c h e m i c a l o r

a s m a n u r e . I t c a n a l so b e h e a t e d u n t i l i t e s c a p e s a n d i s o x i d i s e d . I n a l l c a se s c a r e i s

t a k e n t h a t n o p o l l u t i o n o c c u r s .

T h e p r o p e r t i e s a n d s w e l li n g p r o c e s s e s o f c o tt o n f i b re s a f t e r t r e a t m e n t w i t h l iq -

u i d a m m o n i a a re c o m p a r e d w i th c o n v e n t i o n a l a n d h o t m e r c e r i z e d c o t to n i n T a b le

9 .3 . T h e n a t u r e o f t h e i m p r o v e m e n t i n p r o p e r t i e s r e s u l ti n g f r o m t h e tr e a t m e n t o f

c o t t o n w i t h l i q u i d a m m o n i a d e p e n d s o n t h e c o n d i t i o n s o f i t s r e m o v a l f r o m t h e

f ib r e . D r y r e m o v a l o f a m m o n i a a f t er tr e a t m e n t c o n v e r t s C e l l u l o se I t o C e l l u l o se I I I,




T A B L E 9 . 3

Co m p ar i s o n o f V ar io u s Sw e l l i n g P ro ces s e s [ 1 17 ]Mercer iza t ion

Co n v en t i o n a l H o t

L i q u id a m m o n i a t r e a tm e n t

NH3/H20 NH3/dry-s team

Ch a rac t e r i st i c s o f s w e l l in g p ro ces s e s

Sp eed Re l a t i v e l y l o w

D eg ree H i g h

E v en n es s U n e v e n i n

t igh t ly cons -

t ruc ted fabr ics

Re la t ive ly fas t

D ec reas es w i th

t emp era t u re

G o o d

Shrinkage forces R elat iv ely sm al l sh rinka ge forces

and exh ib i t good e x tens ib i l i ty in

swo l len condi t ion .

Properties.

Lu s t re La rg e i n c reas e Imp ro v ed

D y e t ak e -u p S t ro n g ly

increased

St reng th

D i men s i o n a l

s tabi l i ty

Res i s t an ce t o

d e f o r m a t i o n

Very fas t Very fas t

Som ewh at l ess than ho t caus t ic

G o o d G o o d

H i g h s h r i n k ag e fo rces , m ay

lead to di ff icul t ies in maintain -

i n g ex ac t d i men s i o n s .

Imp ro v ed O n l y s l ig h t ly

but not qui te increased.as high as

mercer iza t ion .

No t qu i t e as h igh 80-90 % Sl igh t ly o r no

c o m p a r e d i m p r o v e m e n t .

to conve n-

t iona l m er-

cerzat ion.

Imp ro v em en t i n th e t r ea t men t o f y a m o r k n i t g o o d s, n o n e i n t h e

t rea tm ent o f fabr ic . S im i la r e f fec t fo r a l l m ethods .

Sim i la r e f fec t by a ll method s . On h eav y and t igh t fabr ics , NH 3

t r ea tm en t s h av e t h e ad v an t ag e .

Re l a t iv e l y So m ew h a t s o f te r

s t if fe r and hand

harshes

Dry crease recov ery ang le (C .R.A.) i s scarce ly

altered.

Sim i la r to Sof te r and

hot m ercer - m ore res i li en t .

zat ion

Dist inct ly

increase dry C.R.A.



M e r c e r i z a t ion 313

a nd the r e i s ha r d ly a ny inc r e a se in dye d if f us ion . The a m m on ia - wa te r sys t e m g ive s

a n i m p r o v e m e n t i n c o l o u r y i e l d in s u b s e q u e n t d y e i n g w h i c h i s o n l y s l i g h tl y l es s

tha n tha t ob ta ine d by m e r c e r i z ing [ 118] . Th i s ha s be e n a t t ribu te d to the c h a nge s in

i n te r n a l v o l u m e a f t e r a m m o n i a t r e a t m e n t [ 49 ]. T h e m o i s t u r e r e g a in a n d w a t e r a b -

so r ba nc y o f f ib r e s tr e a t e d wi th li qu id a m m onia a r e inc r e a se d c om pa r e d w i th va lue s

o f u n t r e a te d f ib r es , w h e r e a s b o t h t h e s e p a r a m e t e r s a n d d y e i n g p r o p e r t i e s o f m e r -

c e r i ze d c o t t o n a re a d v e r s e l y e ff e c te d b y l iq u i d a m m o n i a t r e at m e n t . " S a n f o r e s t "

p r o c e s s p r o d u c e s a s h r i n k p r o o f m a t e r i a l w h i c h d o e s n o t o n l y s h r i n k i n d o m e s t i c

wa sh ing ( a s i s t he c a se w i th S a nf o r i se d m a te r i a l ) bu t a l so no t du r ing d r y ing in

t u m b l e r d r y e rs . T h e t r e a t m e n t w i t h l i q u id a m m o n i a p r o d u c e s n o n - i ro n p r o p e r t i e s

wi thou t lo s s o f s t r e ng th , suc h a s one m us t pu t up wi th in the so - c a l l e d non- i r on

f in i sh ing p r oc e sse s . A t the sa m e t im e the we a r ing p r ope r t i e s o f t he m a te r i a l a r e

im pr ove d ; i t a c qu i r e s a sm oo the r su r f a c e , be t t e r unc r e a s ing a ng le s a nd so f t a nd

p l i a b le ha nd le ( Ta b le 9 .4) . The s t r e t c h ing o f the f a b ri c w i th 6 0 - 8 0 % a m m on ia no t

on ly a vo ids sh r inka ge du r ing the t re a tm e n t bu t a lso c om pe nsa te s f o r sh r inka ge du r -

ing sc our ing a n d b le a c h ing . The a sh ing sh r inka ge po te n t i a l i s g r e a t ly r e duc e d a nd

f a b r i c s t r e a t e d in th i s m a nne r a r e m or e r e s i s t a n t t o sh r inka ge th r ough r e pe a te dwa sh ings ( F ig . 9 - 28 ) . L iqu id a m m onia t r e a tm e n t p r io r t o r e s in a pp l i c a t ion wi l l

im p r ove the re l a t ionsh ip be tw e e n s t r e ng th a nd c r e a se r e c ov e r y a nd inc r e a se r e s i s -

t a nc e in m o s t c a se s to t e ns il e , te a r s t r e ng th a nd a b r a s ion ( Ta b le 9 .5 ). L iqu id a m m o-

n ia i s foun d to r e duc e f ib r i l la t ion in the l a unde r ing o f r e s in - f in i she d goods . A c om -

b i n a t io n o f s l a c k m e r c e r i z a ti o n a n d l iq u i d a m m o n i a t r e a t m e n t f o r th e p r o d u c t i o n o f

c o t ton s t r e tc h f a b r ic s ha ve be e n r e po r t e d [ 124 ]. I t i s al so poss ib l e to c om bine l iqu id

a m m o n i a t r e a t m e n t w i t h d y e i n g i n t o a s i n g l e o p e r a t i o n a s i n t h e c a s e o f " R a p i d

a n h y d r o u s m e t h o d " . L i q u i d a m m o n i a t r e a t m e n t i s f o u n d t o h a v e l e s s p o l l u t i o n

p r o b l e m b u t c o m p a r a t iv e l y a n e x p e n s i v e p ro c e s s . T h e m o s t i m p o r t a n t c o s t e l e m e n t

i s t he r e c ove r y o f a m m onia w h ic h invo lve s r e f rige r at ion . The l iqu id a m m onia t r e a t -

m e n t c a n a l so be a pp l i e d in the p r e - a nd a f t e r - t r e a tm e n t s w i th o r ga n ic so lve n t s ,

s inc e no w a te r i s u se d a n d the l iqu id a m m onia c a n be l a r ge ly re c ove r e d . T he r e i s no

da n ge r o f t he pe r so nne l be ing t r ou b le d by sm e l l , e tc . , s inc e the m a c h ine s a r e he r -

m e t i c a l ly s e a l e d a nd the p r oc e ss i s c a r r i e d ou t i n a c lo se d sys t e m whic h i s unde r

s l igh t va c uu m .




T A B L E 9 . 4

M e c h a n i c a l P r o p e r t i e s o f a 1 0 0 % L i n e n F a b r i c f o r G a r m e n t s

P r o p e r t i e s C o n v e n t i o n a l F i n i s h i n g w i t h

f in i s h i n g d r y c o n d e n s a t i o n

W i t h o u t W i t h

N H 3 N H 3

F i n i s h i n g w i t h d a m p

r e t i c u l a t i o n

W i t h o u t W i t h

N H 3 N H 3

S h r i n k a g e a f t e r 5

w a s h i n g s a t 4 0 ~

W a r p - 8 % - 3 . 5 0 % - 1 . 1 0 %

W e f t - 8 % - 3 . 5 0 % - 2 . 0 0 %

C r e a s i n g a n g l e

( W a r p + W e f t )

D r y 1 2 7 ~ 1 7 0 ~ 2 5 0 ~

W e t 1 2 4 ~ 1 6 5 ~ 2 3 5 ~

W a s h - a n d - W e a r b e h a v i o u r

( M o n s a n t o ) 1 .5 3 4 . 3

A b r a s i o n r e s i s t a n c e

( A c c e l e r a t o r

3 ' 0 0 0 r p m / 1 2 0 ' ) - 1 0 % - 3 2 % - 1 6 %

- 4 . 2 0 % - 1 . 2 0 %

- 4 . 0 0 % - 1 . 5 0 %

1 4 5 ~ 2 4 0 ~

1 7 0 ~ 2 6 5 ~

3 . 5 4 . 5

- 2 6 % - 1 0 . 5 0 %

~ D

.=_

8

7

6

3

o - " - . . . . . .

o i 0 211 311 411 50 611 711 811

N u m b e r o f w a s h i n g s

F i g u r e 9 - 28 . S h r i n k a g e a f te r m u l t i p l e w a s h i n g s ; c o t t o n

f a b r i c f o r p r o f e s s i o n a l c l o t h i n g s , 2 9 0 g / m 2.

1 B l e a c h e d ; 2 B l e a c h e d + N H 3 ; 3 B l e a c h e d + N H 3 + R e s i n .




T A B L E 9 . 5

R e s u l t s o f t h e A m m o n i a T r e a t m e n t o n C o t t o n F a b r i c [ 1 2 0 - 1 23 ]

G r e y f a b ri c B l e a c h e d B l e a c h e d + B l e a c h e d +

s a m p l e NH 3 N H 3 + r e s i n

T e n s i l e s t r e n g t h

W a r p 1 1 91 .9 N 1 2 67 .5 N 1 3 93 N 896 .6 N

W e ~ 890 .7 N 864 .3 N 879 N 662 .2 N

E l a s t i c i t y

W a r p 1 6 . 3 0 % 1 0 . 2 0 % 1 1 . 2 0 % 1 2 . 4 0 %

W e f t 1 1 . 1 0 % 1 5 . 6 0 % 2 0 . 8 0 % 1 3 . 8 0 %

T e a r s t r e n g t h

W a r p 5 0 .2 N 2 9 .3 N 3 0 .8 N 4 8 .3 N

W e t t 4 8 .1 N 2 4 .0 N 2 8 .2 N 4 0 .2 N

C r e a s i n g a n g l e

D r y 1 83 .6 ~ 1 93 .2 ~ 2 2 0 ~

W et 128 .8 ~ 143 ~ 235 ~

C r e a s i n g a n g l e ( 3 '0 0 0 r p m / 9 0 s ) 4 . 4 0 % 3 . 6 0 % 3 . 9 0 %

R E F E R E N C E S

1 G .E . C o l l i n s a n d A . M . W i l l i a m s , J . T e x t i l e I n s t . , 1 4 ( 1 92 3 ) T 2 87 .

2 G .F . D a v i d so n , J . T e x t i l e I n s t. , 2 7 ( 1 3 6) T 1 1 2 .

3 H . F i c h e r , T e x t i l v e r e d l u n g , 1 3 ( 1 978) 5 07 .

4 P . G r ~ i n g , T e x t i l v e r e d l u n g , 1 3 ( 1 978) 5 1 0.

5 J .O . W a r w i c k e r , R . J ef f ri e s, R . L . C o b r a n a n d R . N . R o b i n so n , Sh i r l e y I n s ti t u te

P a m p h l e t n o . 9 3 , M a n c h e s t e r ( 1 9 6 6 ) .

6 C . R . N od de r , J . Tex t i l e Ins t . , 13 (1922 ) 61 .

7 H . F . C o w a r d a n d L . Sp e n c e r , J . T e x t i l e I n s t. , 1 4 ( 1 92 3 ) T 3 2 .

8 R .W . W i l l o w s a n d A . C . A l e x a n d e r , J. T e x t i l e In s t ., 1 3 ( 1 92 2 ) T 2 3 7 .

9 R . B a r t u n e x , D a s P a p i e r , 9 ( 1 95 5 ) 2 5 4 .1 0 R . B a r t u n e x , D a s P a p i e r , 1 6 ( 1 962 ) 5 68 .




11 M. Sado v , M. Korchag in and A. Ma te tsky , Ch em ica l Tec hnolog y of F ibrous

M ater ia ls , Mir Pub . , M oscow , 1973 , p 211 .

12 R Bartunex, Kolloid Z. , 146 (1956) 35.

13 W . D. B anc rof t and J. B. Chalkin , Texti le Res. J. , 4 (1934) 119.

14 W . D. B anc rof t and J. B. Chalkin , J . Phys. Ch em ., 39 (1935) 1 .

15 S. M. Ne ale , J . Tex ti le Inst . , 20 (1921) T 373.

16 J . T . M arsh , Mercerz ing , Ch apm an and Hal l , London , 1951 .

17 J . D 'A ns and A. Jaeger , Ce l lu losechem , 6 (1925) 137 .

18 C. F. Go ldhw ait , Texti le Res. J ., 35 (1965) 987.

19 G. Lal , Texti le Res. J . , 44 (1974) 313.

20 T. Oka no an d A. Sarko, J . Poly. Sci . , 29 (1984) 4175.

21 T. Oka no an d A. Sarko, J. Ap pl. Poly. Sci., 30 (1985 ) 325.

22 H. N ish im ura and A. Sarko, J. Appl. Poly. Sci ., 33 (1987) 855.

23 H. N ish im ura an d A. Sarko, J. Appl. Poly. Sci ., 33 (1987) 867.

24 C. Steinbrin ck, Biol . Z bl . , 26 (1906) 657.

25 J. M. Preston, Trans. Fara da y Soc. , 29 (1933) 65.

26 G. M. Ven kate sh and N. E. Dw eltz , J. Appl. Poly. Sci ., 20 (1976) 273.27 Ha ndb ook of F ibre Sc ience and Tech nology , Vol . 1 , Par t A (Eds . M. Lew in

and S. B. S e l low) Marce l l Dekker , Inc . , N ew York and B ase l , 1983 , p . 1373 .

28 K. Hess and C. Trog us, Z. Phys. C hem ., B 43 (1939) 309.

29 K. Hess and C. Trog us, Z. Phys. Ch em ., B 12 (1931) 381.

30 K. Hess , C. Trogus and S chw arzkopf , Z . Phys . Chem. , A 162 (1932) 187.

31 J. B lackw ell , K. H. Gardner , F. J . Kolp ak, R. M inke and W. B. Claffey, ACS

Sy m pos ium Ser ies No . 141 , Ch . 19, Am . Chem. Soc ., W ash ing ton . D. C. ,

1980, p 315.

3 2 C. Trogu s and K. Hess, C ellulos ech em , 15 (1934) 1 .

33 J. B. Cha lkin , Z. Phys. C hem ., 40 (1936) 27.

34 H. So bue, H. Kie ssig and K. Hess, Z. Phys. Chem ., B 43 (1939) 309.

35 K. Hess and C. Trogus , Z . E lek t rochem , 42 (1936) 696.

36 J . Ch ed in and A. Ma rsaudon , M akrom ol Chem . , 15 (1955) 115 .

37 J . Ch ed in and A. M arsaudon , Mak rom ol Chem . , 20 (1956) 57 .

38 J . Ch ed in and A. M arsaudon , M akrom ol Chem . , 33 (1959) 195 .39 H. J . Phil ips, M. L. N elso n and H. M. Ziff le , Texti le Res. J ., 17 (1947) 585.




40 R. S . Or r , A. W . Burgis , J . J . Cree ly , T . Ma res and J . N. Grant , Te xt i le Res . J . ,

29 (1959) 355.

41 A. Sak thiv el , Diss. Abstr . Int . , B 49 (5) (1988) 1744.

42 A . Tu r ba k a nd A . S a k th ive l , C H EM TE C H . , 20 ( 7) ( 19 9 1) 444 .

43 L . Fou r t and A. M. S ookn e , Text i le Res . J. , 21 (1951) 469.

44 L. Fo ur t and H. J. Ell iot , Te xti le Res. J . , 25 (1955 ) 11.

45 L . Four t a nd A . M . S ookne , Am e r . Dye s tu f f R e p . , 43 (19 54) 30 4 .

46 O. M eche e ls , Me l l iand Text i lbe r . , 13 (1932) 645.

47 D. Be ch ter , Tex ti l Prax is Int . , 31 (1976) 1431.

48 D. Be chte r , Texti l Praxis Int ., 33 (1977) 178.

49 R . S . Or r , A. W . Burg gs , E . R . An drew and J . N. Grant , Tex t i le Res . J ., 27

(1959) 349.

50 H. W ak eh am and N. Spice r, Text i le Res . J ., 21 (1951) 187 .

51 H. W ak eh am and N. Spice r , Tex t i le Res . J. , 25 (1955) 585.

52 B .R . She la t , T . Ra dh akr is hn an and B . V. Iye r , Tex t i le Res . J. , 30 (1960) 836.

53 B .R . She la t , T . Ra dh akr is hn an and B . V. Iye r , Tex t i le Res . J. , 29 (1959) 322.

54 S . H. Zeronian , K. W. Alger and K. E . Cabradi l la , J . Appl . Poly . Sc i . , 20(1976) 1689.

55 J . J . He rber t , L. L. M uller , R . J . Sc hm idt and M. L. Ro ll ins, J . App l. Poly.

Sci . , 17 (1973) 585.

56 J . W . S. He ar le an d J. T. Sparro w, J . App l. Poly. Sci . , 24 (1979) 1465.

57 S .H . Z eron ian , H. Kaw aba ta and K. W . Alger , Text i le Res . J ., 60 (1990) 179 .

58 C . F. Go ldhw ai t , Te xt i le Res . J ., 47 (1977) 632.

59 L . Ch eek, A. W ilco ck and L . Hsu, Tex t i le Res . J ., 57 (1987) 690 .

60 S . A. Heap, Co lourag e , 23 (3) (1976) 28.

61 J . H. M orto n, J . Soc. Dy ers Colo urists , 92 (1976) 149.

62 G. Go ldf ing er , Tex t i le Res . J ., 47 (1977) 633.

63 K. Bred ereck , Mel l ian d Tex t i lbe r , 59 (1978) 648 .

64 J . K. Ske lly, J. Soc. Dy ers Co lou rists , 76 (1960) 469.

65 K. Bred ereck , Te xt i lve re dlun g, 13 (1978) 498 .

66 L . Ch eek an d L . Ro usse l , T ext i le Res . J ., 59 (1989) 478 .

67 H. Herz og , Tex t i lbe r ichte , 1 (1920) 136.68 I. Lam br in ou, M el l ian d Text i lbe r . , 63 (1975) 526.




69 J . Ko pez yns ki and A. W locho wic z , Text i le Res . J ., B6 (1966) 967.

70 A. J. Tu rner, J . Te xt i le Inst . , 40 (1949 ) 857.71 S .K . Bat ra , Other Lon g Fibres , Ma rcel l Dekker Inc . N ew Y ork , 1985, p 727.

72 J . O. Wa rw icke r, J . Poly. Sci . , Part A-2, 4 (1966) 571.

73 H. S. S. Sha rm a, T. W . Fraser, D. McC all , N. Sh ield and G. Lyo ns, J. Te xt i le

Inst. , 86 (4) (1995) 539.

74 W . Wel tz ien , Text i lber . , 7 (1926) 338.

75 R. S. Bh ag w at , Colou rage , 38 (2) (1991) 61.

76 S. Grief , Me ll iand Te xt i lber. , 72 (9) (1991) 753.

77 Ano n. , Tex t i lvered lung, 13 (1978) 527.

78 W . Pac ksc hies , Tex t i l Praxis , 31 (1976) 1170, 1179.

79 J . D. Tu rner, W . A. Bla nton and L. Kra vetz, Te xt i le Res. J. , 52 (1982) 73.

80 E. Gass m ann, Tex t i lveredlung, 13 (1978) 514.

81 G. Lom bard i , Colourage, 32 (7) (1985) 23.

82 J . R. M od i and A. M. Patel , A T IR A Techn ical Dige st , 19 (1) (1985) 4.

83 An on . , Int . Te xt i le Bull . , Dy g/Ptg /Fing . , (1982) 309.

84 L. H. Hu nter and S . Sm uts , SW AT RI Tech. Repor t , 390 (1978).85 P. K. Hari , Text i le Res. J ., 55 (1985) 630.

86 H. E. Bi l le , W. Th oniog and G. Smidt , Am er . Dy es tu ffR ep . , 61 (1972) 56.

87 P. F. Gre en w oo d, J . Soc. Dy ers Colo uris ts , 103 (1987) 342.

88 P.F . G reenw ood , Br . Kni t t ing Ind ., ( Ju ly 1972) 77.

89 H. W eber , Mo de m Trend s in Me rcer iza t ion (Benn inger , 1972).

90 An on. , Industrie Tex t i le, 1061 (N ov 1976) 633.

91 An on. , Dy er, 161 (1979) 500.

92 Ano n. , Kni t t ing Times (15 Aug 1977) 24 .

93 Ano n. , In t . Tex t i le Bul l ., Dy g/Ptg/Fing (1981) 104.

94 Ano n. , In t . Tex t i le Bul l ., Dy g/Ptg/Fing (1985) 71 .

95 Ano n. , Me l l iand Text i lber . , 66 (1985) 138.

96 Anon. , Dyer, 169 (10) (1984) 12.

97 P.F . Gree nw ood , Text i le Inst . and Ind . , 14 (1976) 373.

98 L indauer Dorn i e r Gm bH, L ' Indus t r i e Tex t il e (1976) 1062 , 707 .

99 E. W orth , Te xt i lbetr ieb , 95 (1977) 56.100 D. Bechter , D. Fiebig and S . A. Heap, Te xt i lveredlung, 9 (1974) 265.




101 E .K . Bo yls to n and J . J . Heber t , Tex t i le Res . J ., 49 (1979) 317.

102 D. Bec hte r , Text i l Praxis , 31 (1976) 1431.

103 D. Bec hte r , Tex t i l Praxis , 33 (1978) 75 .

104 D. Bec hte r , Te xt i lve redlu ng , 13 (1978) 490 .

105 D. Bech te r and G. Bu cher , Te xt i l Praxis , 39 (1984) 680.

106 N. Ah m ed a nd K. D. Tah i r , Tex t i le Hor izon, 5 (2) (1985) 20 .

107 J . R . Mod i and A. M. Pa te l , ATIR A Tech. Dig es t , 19 (1) (1985) 4 .

108 D. Bech te r , Tex t i lve red lung , 21 (1986) 256 .

109 K. Bre der eck and R . Pfund te r , Text i lve red lung , 10 (1975) 92 .

110 K . B r e d e r e c k a nd R . W e c km a nn , M e l l i a nd Te x t i lbe r ., 58 ( 19 7 7 ) 310 .

111 K. Br ede reck and R . W eck m an n, M el l iand Text i lbe r . , 59 (1978) 137.

112 K. Bred ereck , M el l ian d Text i lbe r . , 59 (1977) 310 .

113 K. Bre dereck , Mel l ia nd Text i lbe r . , 60 (1979) 1027.

114 K. Bred ereck , Tex t i l Praxis , 36 (1981) 1010 .

115 K. Bre dere ck and A. Saafa r , M el l iand Tex t i lbe r . , 63 (1982) 510 .

116 R .M . Ga i ly , C onf . Pr oc . i n L iqu id Am m onia T r e a tm e n t o f C e l lu lose Te x t il e s ,

Shi r ley Ins t i tu te , Manches te r , England, Nov 19 , 1970 , pp 34 .117 K. Bred ereck , Te xt i lve redlu ng, 13 (1978) 498 .

118 T. W ak id a e t a l . , Te xti le Res. J . , 111 (1995) 154.

119 J . A. Ca lamar i , S . P . Schre ibe r and A. S . Cooper , Text i le Chem. Color . , 13

(1971) 61.

120 M. Rah ee l an d M. D. L ien , Text i le Res . J. , 52 (1982) 493.

121 M. Ra hee l and M. D. L ien , Text i le Res . J ., 52 (1982) 555.

122 M. Rah ee l , Te xt i le Res . J ., 53 (1983) 557 , 639 .

123 B .W . Jones , J . D. Tu rner and D. O. Luba re l lo , Text i le Res . J ., 50 (1980) 165.

124 US P 43459 0 8 ( 19 8 0 ) .



Chapter 10

O P T I C A L B R I G H T E N I N G A G E N T S

1 0 . 1 I n t r o d u c t i o nText i le f ibres do not appear pe r fec t ly whi te due to the presence of ce r ta in colou red

im pu r i ti e s . Du r ing c he m ic a l b l e a c h ing , c o lou r e d im p ur i t ie s a r e e ithe r de s t r oye d o r

deco loured b y oxida t ion or reduc t ion . Ov er -b leaching m ay reduce the f ibre s t rength .

Ev e n we l l b l e a c h e d f a b r i c s posse s s a s l igh t ye l low ish a ppe a r a nc e . Th i s ye l lowish

hue o f the m a te r i a l s c a n be e l im ina te d by wh i t e n ing wi th op t i c a l b r igh te ne r s o r

f luo r e sc e n t b r igh te n in g a ge n t s ( OB A or FB A ) . S om e t im e s b lue ing a ge n t s a re a lso

use d . I n ' b lue ing ' t he in i ti a l ye l low ish sha de o f the t e x ti l e s is c ove r e d by the b lue

dye a nd a b lu i sh w h i t e r e su l ts . How e ve r , t he c o r r e spond ing b lue dye i t s e l f a bso r bs

in v is ib le l ight and thu s the to ta l amo un t of re f lec ted l ight i s smal le r than in the case

o fu n bl ue d m ate r ia l , so tha t the b lued m ja te r ia l i s le ss br igh t i. e ., i t i s dul l , o r grey-

ish.

The op t i c a l b r igh te ne r s c oun te r a c t t he ye l lowne ss o f the f a b r ic by inc r e a s ing the

r e f l e c t ion o f b lue l i gh t r a ys . The y c o nve r t i nv i s ib l e sho r t - wa ve u l t r a v io le t ra ys o f

sun l igh t i n to v i s ib l e b lue l i gh t a nd ha s a de g r e e o f wh i t e ne ss wh ic h i s c om pa r a -

t ive ly m or e in t ense . F ig . 10 - 1 i l lu s t r a t e s a c om pa r i son o f the poss ib l e spe c t ra l

. . . . . . . . . . . . . . . . . . . . . . ~ . . . . . . . . . . . . . . . . . :. . . i _ -_ . :, : -

8 0 A . .. ... . ' . . . . . . . . . . .

8

6 0 " "

q~40

' 2. . . . . . . 1 . . . . . . . . . . . . . . . I . . . .

3 0 0 4 0 0 5 0 0 6 0 0 ? 0 0

N a n o m e t e r s ( n m )

F igur e 10- 1. R e f l e c t a nc e o f a b l e a c h e d c o t ton f a b r ic ( A) , a ft e r a dd ing a b lue t i n t

(B) and a f te r add ing a f luore scen t br ighte ner (C) [1 ] .

r e f l e c t a nc e s o f a f a b r ic a f t e r b lu ing a nd op t i c a l wh i t e n ing . The 10 0 % r e f le c t a nc e



Opt ic a l B r igh te n ing Age n t s 321

whic h r e p r e se n t s a pu r e wh i t e l i gh t i s shown a s a s t r a igh t l i ne pa r a l l e l w i th the

hor i z on ta l c o - o r d ina te . C ur ve A w hic h r e p r e se n t s the b l e a c he d c o t ton de v ia t e s f r om

the ide a l , wh i l e the f a b r i c w i th b lue t i n t ( C ur ve B ) i s a ppa r e n t ly wh i t e r a l though

the r e i s som e los s o f i n t e ns i ty a nd l e s s r e f l e c ta nc e . T he f a b r ic t r e a t e d w i th wh i t e n -

ing a ge n t ( C ur ve C ) im pr ove s the d i s t r ibu t ion ove r the spe c t r a l r e f l e c t a nc e s a nd

a l so a dd to the to t a l a m o un t o f l i gh t r e f le c t e d , t hus g iv ing w h i t e ne ss o f ou t s t a nd ing

br igh m e ss . One po ss ib l e r e a son f o r h igh r e f l e c ta nc e in the v i s ib l e r e g ion i s t ha t t he

f luo r e sc ing m a te r i a l doe s no t a bso r b l igh t i n the 40 0 - 50 0 nm r e g ion a nd e xh ib i t s

the e f f e c ts o f e m is s ion . Th e w h i t e n ing e f f e c t g ive n by the op t i c a l b r igh te ne r i s thus

a n a dd i t ive e f f e c t, wh i l e tha t p r od uc e d b y ' b lu in g ' i s a subs t r a c t ive e ff e c t.

1 0 .2 C h e m i c a l C o n s t i t u ti o n o f O p t i c a l B r i g h t e n e r s

T h e p r o d u c t i o n a n d c o n s u m p t i o n o f o p t ic a l b r i g h t e n e rs a r e c o n s t a n tl y i n c r ea s -

ing a nd the a nnua l i nc r e a se i s a m oun te d to a bou t 10 - 12%. I n a dd i t ion to t e x t i l e ,

de te rg ent and pap er indus t r ie s (Table 10 .1), opt ica l br igh tening agents a re a lso used

T A B L E 1 0 . 1

C o n s u m p t i o n o f O p t i c a l B r i g h t e n i n g A g e n t s

B r a n c h C o n s u m p t i o n ( % )

D e t e r g e n t m i x t u r e 4 0

Pa pe r 30

Text i le s 25

S yn the t i c f ib r es & p la s t i c s 5

f o r the b r igh te n ing o f f ea the r , f at s , ge l a t ine , wo od sha v ings a nd sa nd dus t , f o r t he

b r igh te n ing o f pa in t s , l e a the r, f u r s , s t ra w a nd in the pho tog r a p h ic indus t r i es .

F l u o r e s c e n t b r i g h t e n in g a g e n t s a r e o r g an i c c o m p o u n d s , w h i c h w h e n p r e s e n t o n

te x t i le f ib r e s , e xh ib i t f l uo r e sc e nc e . FB As r e se m ble dye s in a ll r e spe c t s e xc e p t tha t

the y ha ve no v i s ib l e c o lou r a nd a r e thus c a l l e d c o lou r l e s s dye . The y a r e subs ta nc e s

n o r m a l l y h a v i n g a s y s t e m o f c o n j u g a t e d d o u b l e b o n d s [ 2] a n d m u s t b e e s s e n t i a ll y

p la ne r a nd shou ld c on ta in e l e c t r on don a t ing g r oups suc h a s OH, N H 2 e tc . a nd be

f r om e le c t r on a c c e p t ing g r oups suc h a s NO 2, - N = N - e tc . Ta b le 10 .2 c on ta ins a

se l e c t ion o f im por t a n t ba s i c s t r uc tu r e s w i th r e f e r e nc e to the m a in f i e ld o f the i r

d e r i v a ti v e s . T h e m a j o r i ty o f t h e c o m p o u n d s a re b u il t up f r o m a r o m a t i c a n dhe te r oa r om a t i c s t r uc tu r a l e le m e n t s wh ic h a r e r e c onn e c te d toge the r e i the r by d i r e c t



322 Opt ical Br ightening Agen ts

TABLE 10 . 2Chem ica l Cons t i tu t i on o f S ome Im por t an t Op t ica l W hi t ener s [ 3 , 4 ]

Fie lds o f appl ica t ionand subs t ra tes

General basic s t ructures Subst i tuents

- N HO3S N - -R =H -a lky l ,Textiles, R , \ ~( ~N_g__~___~ ._ .C /__~~___N_ j ~ 1~2 ' SO3Ude tergen ts / / ~ / /Polyamide R2~ N / x ~ / ~ ~ ~ / ~ \N //&" R1 ~ < ~" SO 3H(T,W). 4, 4'-bis-(),-triceol-zoyl) stilbene-

Textiles, de tergen ts , 2-2' disulphonic acids H

melt s ,lasticsSpinningo l u t i o n s / R ~ / O ~ / 0 \ / / ~ R -X=~~(~~=" ~ ~t @

P o l y a m i d e ( T ,W ) , K ' v " r~/ ~ , / ~ - X - ~ N ~ RPolyes t e r (T , W , S ) ,P o ly v in y l ch lo r id e . . . . . . . - R =- H ,- C (C H 3 ) 2 , u HOlS-toenzoxazo~y~)- H(K! , Poly styre ne (K! , de rivativ es ~ 3/~-----~z "~ ll - ~ : C - - C : C - - - ( @_.r~176 t ry ) , -~ - ~ k . , , l - I 3 l--I H

lnaceta te(T,S) . CH3 R H CH CH CO OHTe xtil es, de ter ge nt s, Sp in- R - t= ' 3" ~Z2~,in ing so lut ions/melts , p las- ~... /~..--~ .. ,-, , , , ~ % ~T ~,~ TT r~T~ ,~,-,r,~Ttics f" "~ ~ ' (K, -1~2 -- IN~_ _~ , " , ~ t-'l-13Gl-12%kYk)l-1Polyamide (T,W ), Poly ester R.Z~/Ak..n/J, ,, ., ~ ~ N . . ~ H , x,(S), Polyacryloni tr i le (T), " '3 - --'- t9 .N--< / N ~ / ~ . ~/~ '~'- , . /

PVC (K) Cou m ar ins -R3= -N(-~ N , - N I ) --N . _~

Texti le , de tergen ts R.W o ol (T ), S ilk (T ), T r ia c - R ~ / N . ~ _ ~ < - ~ > Retate (T), Polyac rylonitrile // '~ 2(T), Polyam ide (T,W ).

Pyrazolins

-R1= -N, -C1

-R2=C1, -SO 3H , -SO 2N H 2.

-SO2NH, SO2CH 3

- R 3 , - R 4 = - H , A l k y l - ~

-Rs=H, -C1

Textiles O , ( f - - - ~ R - R t : a l k y l , - (C H 2)3 N (C H 3) 2Polyester (T), Polyacrylonitrile ( T ) , ~ 2S ec . a c eta te ( T ), T ria ce ta te ( T ) . R ~ - T O ~ , ~ . -R2=-O a l k y l , - S O 3 H ,

- N H C O C H 3Naphthalimides

Texti le s , de tergents 411 .t-&O/ N/ -~I -Polyamide (T,W), Polyester R ~ - ~ R(T ,W ). R ' ~ ~ N / H

R22-styryl-benzoxazoles

and naphthoxazoles

Texti le s , Spinningso lut ions/meltsPolyester (T ), Polyamides (S).

- R ~ = C N , - C O O a l k y l , - C 1

-R2+R3 =I -R3 , -Rs=H, - a lk y l

-R 4=H , - a l k y l - ~ ~

H O . . ~ - R ~

a lky l -S O2 CH 34-phenyl-4'-benzoxazolyl stilbene

T = Text i les , W = Deterge nts , P = Pape r, S = Spin ning so lut ions, K = Plast ic.



O p t i ca l B r i g h te n i n g A g e n t s 323

b o n d s o r b y e th y l en e b r id g e s . T h es e l a t te r s e rv e a s n - e l ec t r o n b r id g es an d co n n ec t

th e r e s o n a n ce s y s t em s w i th o u t i n t e r ru p t in g t h e co n t in u o u s co n ju g a t io n e s s en t i a l t oth e w h i t en e r m o lecu l e (T ab l e 1 0 . 2 ) . By f a r t h e g r ea t e r n u m b er o f co m p o u n d s a r e

d e r iv a t i v es o f s t il b en e , b en z id in e , b en z th io zo l e , b en zam in azo l e , b e n zo x a zo l e , co u -

m ar in , p y r az o l in es e t c. [ 3 ] . Ab o u t 80% o f al l o p t i ca l b r i g h t en in g ag en t s p r o d u ced

a r e d e r iv ed f r o m s t i l b en e . T h e w o r ld m ar k e t n o w ca r r i e s m o r e t h an 2 5 00 t r ad e

m ar k s , r ep r e s en t in g 2 00 v a r io u s p ro d u c t s b e lo n g in g t o m o r e t h an 1 5 st ru c tu ra l t y p es

[ 4 ] .

1 0.3 M e c h a n i s m o f F l u o r e s c e n t W h i t e n i n g

W h e n a s p e c im en t r an s f o r m s a p a r t o f t h e ab s o r b ed l i g h t i n to l i g h t o f an o th e r

w av e l en g th i n s t ead o f i n to h ea t ( a s is t h e ca s e w i th n o r m a l d y e d s p e c im e n s ) , i t i s

ca l l ed f l u o r e s cen t s p ec im en . F BAs ab s o r b u l t r av io l e t l i g h t i n 3 00 - 4 00 n m r eg io n

f r o m d ay l i g h t an d em i t it i n t h e v i s ib l e r eg io n (4 00 - 4 60 n m ) a t th e b lu e - v io l e t o f

t h e s p ec t r u m . T h e e m i t t ed b lu e l i g h t co m p en s a t e s f o r y e l l o w t in t s o f f i b re s an d a t

t h e s am e t im e th ey a l s o i n c r eas e th e l u m in o s i t y o f t h e g o o d s . T h e em i s s io n s p ec -

t r u m i s ch a r ac t e r i s t i c s o f a p a r t i cu l a r ag e n t o n a g iv en s u b s t r a t e . De p en d in g o n t h e

en e r g y d i s t ri b u t i o n o f t h e s p ec t r u m , t h e f l u o r e s cen t l i g h t em i t ted i s b lu e - v io l e t ,b lu e , b lu e - g r ee n [5 ]. Acco r d in g t o S to k e ' s l aw th e s h ap e o f t h e f l u o r e s cen e b an d

can b e p r ed i c t ed f r o m th e s h ap e an d t h e p o s i t i o n o f t h e ab s o r p t i o n b an d , an d t h e

co lo u r o f t h e f l u o r e s cen ce can t h u s b e d e t e r m in ed . T h e r e l a t iv e d i s t r i b u t i o n o f t h e

em i t t ed l i g h t w i th in t h e em i s s io n b an d i s a l s o im p o r t an t .

T h e m ech an i s m o f o p ti ca l b r i g h t en in g i s a l s o ex p l a in ed o n t h e b as i s o f q u an tu m

th eo r y o f l i g h t an d e l ec t r o n i c s t r u c tu r e o f a to m s an d m o lecu l e s [6, 7] . In t h e f lu o -

r e s c e n t s u b s t a n c e m o l e c u l e s w h i c h h a v e a b s o r b e d r a d i a ti o n ( l i g h t) o f s h o rt w a v e -

l en g th can p as s i n to an ex c i t ed s t a te o f h ig h e r en e r g y . T h es e ex c i t ed m o lecu l e s t h en

r e tu r n t o t h e g r o u n d s t a t e o f l o w er en e r g y w i th r e - em is s io n o f l i g h t q u an t a o n ly

s l i g h t l y s m a l l e r t h an t h o s e ab s o r b ed i . e . , o f l o w er en e r g y an d l o n g e r w av e l en g th

(v is ib le l igh t ) . The av erag e m ea n l i fe o f exc i ted m olec u les i s 10 -s to 10 -9 sec and in

g en e r a l t h e s h o r t e r t h is l if e th e l e s s d i f fe r en ce w i l l b e th e r e b e tw een th e w av e l en g th

o f f l u o r e s cen ce an d em i t t ed l i g h t an d g r ea t e r w i l l b e th e f l u o r e s cen c e a s th e r e w i ll

b e l e s s t im e f o r d i s s ip a t i o n o f en e r g y a s h ea t .

1 0 . 4 F a c t o r s I n f l u e n c i n g t h e F u n c t i o n s o f O p t i c a l W h i t e n e r sOp t i ca l b r ig h t en e r s a r e ap p l i ed t o s u b s tr a t e a s a s ep e ra t e a f t e r - t r ea tm en t p r o ces s



3 2 4 Opt i c a l B r igh te n ing A ge n t s

o r a r e inc o r po r a t e d in to b l e a c h ing a nd f in ish ing ba ths . S inc e the f luo r e sc e n t b r igh t -

ening agen ts behav e l ike dyes tuf f s , the i r e f f ic iency and e f fec t iveness a re inf luenced

by v a r ious f a c to r s tha t a r e im por t a n t i n a pp l i c a t ion .

1 0 . 4 . 1 S u b s t r a t e

The b r igh te n ing e f f e c t is de pe nd e n t on the na tu r e o f the subs t r a te . Fo r e x a m p le ,

a ve r y s t r ong r e f l e c t a nc e i s obse r v e d w i th wh i t e ne d c o t ton , bu t i t i s we a ke r in v i s -

c ose a nd w oo l . A l l syn the t i c f ib r e s a bso r b s t r ong ly in the ne a r u l t r a v io le t r e g ion .

S inc e the f luo r e sc e nc e p r oduc e d by op t i c a l b r igh te n ing a ge n t i s a dde d to r e f l e c -

t a nc e o f the subs t r a te , t he m a x im um f luo r e sc e nc e e f f e c t is a c h ie ve d on those sub -

s t ra te wh ose abi l i ty to absorb the u l t rav io le t r eg ion i s supp ressed by che m ica l br ight -

e n ing . I n the a bse nc e o f su f f i c ie n t a f f in i ty o f b r igh te ne r s , t he a pp l i c a tion r e su l t s i n

ye l low to g r e e n c o lou r y i e ld .

1 0 . 4 . 2 S a t u r a t i o n

Th e r e i s a s a tu r a tion l im i t f o r e a c h op t i ca l wh i t e n ing a ge n t . Abo ve c e r t a in c on-

c e n t r a t ion on the f ib re a ye l low c o lou r i s supe r im p ose d on the f lou r e sc e n c e r e su l t -

ing in de c r e a se in wh i t e ne ss . Th i s i s be c a u se a t h ighe r c onc e n t r a t ion o f b r igh te ne r s

a pro tec t iv e op t ica l layer ( fi l te r ) i s form ed on the sur face of the subs t ra te whic hpr e v e n t s the e x t inc t ion o f the m o le c u le s o f the b r igh te n ing a ge n t in de e pe r l a ye r s

( so ca l led se l f -qu ench ing , co ncen t ra t ion qu ench ing of f luoresce nce or f il te r e f fec t) .

1 0 .4 .3 M e t h o d o f a p p l ic a t i o n

The sa tu r a t ion l im i t o f a n op t ic a l b r igh te n ing a ge n t , how e ve r , i s a lso de pe n de n t

on the m e th od o f a pp l i c a tion to the subs t r a te . Usua l ly e xh a us t a pp l i c a t ion p r oc e ss

g i v e s h i g h e r w h i t e n e s s v a l u e t h e n i t d o e s w h e n a p p l ie d b y p a d d i n g t e c h n i q u e f o r a

g i v e n a m o u n t o f w h i te n e r.

1 0 . 4 . 4 T i m e

Ge ne r a l ly op t i c a l b r igh te n ing a ge n t s ha ve h igh r a t e o f e xha us t ion on the sub -

s t ra te and the re fore grea t ca re i s to be taken to avoid unleve l appl ica t ion . S low

e xh a us t ion r a t e a nd inc r e a se d m ig r a t ion t im e i s ne c e s sa r y to p r oduc e l e ve l wh i t e -

ness on the fabr ic .

1 0 . 4 . 5 T e m p e r a t u r e

The op t im um te m p e r a tu r e s o f op t ic a l b r igh te n ing a ge n t s on c e llu los ic f ib re s a r e

usua l ly be tw e e n 40 a nd 60 ~ a nd f u r the r r i s e in t e m p e r a tu r e t e nd to lowe r thee xha us t ion . Howe ve r , f o r syn the t i c f ib r e s h ighe r t e m pe r a tu r e i s ne e de d f o r good

pe n e t r a t ion o f the b r igh te ne r s .




10 .4 .6 pH

Th e c he m ic a l s t a b i l i ty , so lub i l i t y a nd a f f in i ty o f op t i c a l b r igh te n ing a ge n t s de -

pe nd on e f f e c t ive pH va lue in so lu t ion . Fo r e xa m ple , f o r woo l a nd po lya m ide f i -

b r e s , op t im um pH i s on the a c id i c s ide fo r be t t e r e xha us t ion .

10.4 .7 Sal t

Ge n e r a l ly s a l t i s a dde d in the a pp l i c a t ion ba th to p r om ote a nd a l so to c on t r o l t he

r a t e o f e xha us t ion o f the b r igh te n e r s on c e l lu los ic f ib r e s.

1 0 .5 A p p l i c a t io n o f O p t i c a l B r i g h t e n e r s

T h e a p p l i c a ti o n o f f lu o r e s c e n t b r i g h t e n in g a g e n t d e p e n d s o n t h e k i n d s o f f ib r es

on w h ic h i t i s a pp l i e d a nd a c c o r d ing ly c a n be c l a s s i fi e d a s d ir e c t ( o r subs ta n ta t ive ) ,

d i spe r se a nd c a t ion ic type s . The d i r e c t b r igh te n ing a ge n t s ar e m os t ly de r iva t ive o f

4 , 4 ' - d i a m inos t i lbe n e - 2 , 2 ' - d i su lphon ic a c id a nd a re u se d m a in ly f o r the b r igh te n -

ing o f c o t ton , pa pe r , v i sc ose , l ine n a nd po lya m ide s . Ac id o p t i c al b r igh te n ing a ge n t s

c on ta in f re e su lpho g r oups a n d se r ve m a in ly f o r the b r igh te n ing o f si lk a nd woo l .

B a s ic op t i c a l b r igh te n e r s c on ta in a m ino g r oups a nd inc lude m a in ly r a nd

pyr a z o l ine type s . Th e y a r e u se d p r im a r i ly f o r the b r igh te n ing o f na tu r a l a nd syn -

the t ic po ly a m ide s . D i spe r se op t i c a l b r igh te n ing a ge n t s a r e w a te r i n so lub le c om -pou nds o f va r ious s t r uc tu r e s a nd a r e u se d m a in ly f o r the po lye s te r , c e l lu lose a c e ta te

a nd po lya c r y lon i t r il e . T he y a r e m a in ly t r i a z o ly l s t il be ne s , b i s ( be nz ox a z o ly l ) , e th -

y le ne r e t c. Of t e n m ix tu r e s o f op t i c a l b r igh te n ing a ge n t s w i th v io l e t a nd

b lue /g r e e n typ e a r e u se d to ge t a na tu r a l w h i t e f luo r e sc e n t e f f e c t [8 ], C a t ion - a c t ive

o p t ic a l b r i g h t e n e rs a re c o m p o u n d s m a i n l y o f t he m e t h a n e e t h a n in e t y p e , w h i c h a r e

use d m a in ly f o r the b r igh te n ing o f p o lya c r y lo n i t r i l e f ib r e s.

Op t i c a l b r igh te n ing a ge n t s m a y be ob ta ine d a s powde r s , pa s t e s , l i qu id wa te r -

in so lub le f o r m s o r s t a b le d i spe r s ion . The s t a b i l i s e d d i spe r s ions a r e su i t a b le on ly

f o r in so lub le d i spe r se op t i c a l b r igh te ne r s . Ge n e r a l ly the l i quor s o f t he b r igh te n ing

a ge n t s a r e no t s t a b le to l i gh t a nd sho u ld no t be s to r e d f o r a long t im e o r e xpo se d to

l igh t . The y u nde r go c i s - tr a ns i som e r i sa t ion in a dd i t ion on e xp osu r e to l i gh t r e su l t-

ing in a c om pou nd wh ic h ha s p r a c t i c a lly no f luo r e sce n t e f fe c t. Th e y a l so a c c e le ra t e

the pho tod e gr a da t ion o f t ex t i le m a te r ia l s on e xposu r e to sun l igh t. A n o p t i c al b r igh t -

e ne r sho u ld no t be use d on dye d m a te r i a l s be c a use i t f l a tt e ns the sha de .

Op t i c a l b r igh te n ing a ge n t s a r e a pp l i e d to t e x t il e s a t the t im e o f s c our ing , b l e a c h -ing o r f in i sh ing . W he n c h lo r i te b l e a c he s a r e u se d a n t i - c h lo r ina t ing m e a su r e s m us t



3 2 6 Opt i c a l B r igh te n ing Ag e n t s

be t a ke n . The f luo r e sc e n t b r igh te ne r s sho u ld be s t a b le in the b l e a c h ing ba th a nd

a l so shou ld be s t a b le on the f ib r e a t t he the r m oso l ing t e m pe r a tu r e in the c a se o f

po lye s t e r . I n c on t inuous p r oc e ss ing whe n sod ium c h lo r i t e i s t he b l e a c h ing a ge n t ,

the n f luo r e sc e n t b r igh te ne r s m us t be a pp l i e d a f t e r b l e a c h ing in the wa sh - o f f , bu t

wi th hy dr og e n pe r ox ide b l e a c h in g i t c a n be inc lude d in the pe r ox ide b l e a c h l iquor .

F luo r e sc e n t b r igh te ne r s c a n be a p p l i e d to c o t ton m a te r i a ls p r io r t o r e s in t r e a tm e n t

o r i t c a n be a dde d to the r e s in f o r m u la t ion ba th . How e ve r , p r ope r s e l e c t ion o f c a ta -

ly s t i s ne e de d s inc e c e r t a in c a t a lys t s im p a i r t he l igh t f a s tne s s o f the t r e a t e d f a b ri c .

S om e t im e s op t i c a l b r igh te n ing a g e n t s a re a dde d du r ing po lym e r i sa t ion o f syn the t ic

f ib re s to im pa r t a r e dd i sh to ne u t r a l b lu i sh t i nge to f ib r e [9 , 1 0 ] . M a ss b r ig h te ne d

m a te r i a l g ive s e qua l f luo r e sc e nc e in t e ns i ty th r oug hou t the fib re , wh i l e the t e x t i le

b r igh te n ing e f f e ct s ha ve a r ing o f b r igh t f luo r e sc e nc e w i th l it tl e i n t e ns i ty in the

c e n t r e o f t he c r os s - se c t ion . Fo r b l e nde d f a b ri c s , a m ix tu r e o f two wh i t e ne r s tha t a re

su i t a b le f o r bo th the c om pon e n t f ib re s i s u se d .

1 0 . 5 . 1 C e l l u l o s i c f a b r i c s

Opt ic a l b r igh te n ing a ge n t s wh e n a pp l i e d to c e l lu los i c f ib r e s be ha ve l ike d ir e c t

c o t ton d ye s a nd the i r up ta ke i s i n f lue nc e d by t e m pe r a tu r e, e l e c tr o ly te c o nc e n t r a t ionand l iquo r ra t io e tc . The l inks be tw een f ibre and br ightener involve hy drog en bond s ,

Va n de r W a a l ' s f o r c es a nd in t e r a c t ions o f the d ipo le s o f the b r igh te ne r . The b r igh t -

e ne r pe ne t r a t e s the f ib re in a m ono m ole c u la r f o r m , a nd ha v ing e x pe l l e d a pa r t o f

w a te r i n it , a gg r e g a te s the re , a nd t a ke s on a g r e a t e r vo lum e , w he r e i t c a n no long e r

so eas i ly leave the in te r ior o f the f ibre .

Op t i c a l b r igh te ne r s c a n be a pp l i e d on c e l lu los i c f ib r e s e ithe r by e x ha us t o r pa d -

d ing m e thods . I n the e xha us t m e tho d , g oods a r e e n te re d in to the c o ld l iquor c on-

ta in ing opt ica l br ightener (0 .5-0 .6%, o .w. f . ) and e lec t ro ly te (5 g / l ) and then the

te m pe r a tu r e o f the ba th is r a i s e d to op t im um s lowly ove r a pe r iod o f 15 m in . W he n

r e qu i r e d t e m pe r a tu r e ( de pe nd ing upon the b r igh te ne r s u se d) i s r e a c he d , a f u r the r

30 m in o f r unn ing i s su f f ic i e n t f o r c om ple te e xha us t ion .

W he n p a dd in g m e thods a r e u se d , the f a b ri c is pa dd e d wi th a so lu tion c on ta in ing

0 .0 5 to 4 g /1 b r igh te n ing a ge n t in a two- b ow l m a ng le a t r oom te m p e r a tu r e ke e p ing

8 0 - 10 0 % e xpr e s s ion . The m a te r i a l i s d r i e d a nd s to r e d in da r k . To a c h ie ve good

d i f f us ion , f u ll f l uo r e sc e nc e a nd c om ple te de ve lopm e n t o f the b r igh te ne r , a subse -que n t he a t t r e a tm e n t on s t e n te r o r in c u r ing un i t m a y be g ive n .



O p t i c al B r i g h te n i n g A g e n t s 327

T h e l i g h t f a s m es s p r o p e r t i e s o f t h e d i r ec t o p ti ca l b r ig h t en e r s u s ed f o r ce l l u lo s ic

m a te r i a l s a r e m ed iu m i .e . o f th e o r d e r o f 2 - 3 . O th e r f a s m es s p r o p e r t i e s a r e g o o d to

w a t e r a n d w a s h i n g at 4 0 ~ m e d i u m t o g o o d t o w a s h i n g a t 9 5~ a n d m e d i u m t o

h ea t t r ea tm en t a t t em p er a tu r e s ab o v e 1 5 0~ an d t o s an f o r i s in g .

1 0 . 5 . 2 W o o l l e n f a b r i c

W o o l f ib r e s h a v e a m p h o t e r ic p r o p e r ti e s r e n d e r in g t h e m c a p a b l e o f c o m b i n i n g

w i t h b o t h a c i d i c a n d b a s i c s u b s t a n c e s . H o w e v e r , w o o l c o n t a i n s m o r e n u m b e r o f

b as i c s i d e g r o u p s w h ic h en ab l e t h em to co m b in e w i th ac id t y p e o p t i ca l b r i g h t en e r s

co n t a in in g s u lp h o n i r o r ca r b o x y l i c g r o u p s . T h e m o s t co m m o n b r ig h t en e r s f o r ap -

p l i c a t i o n t o w o o l a r e a s e l e c t e d ra n g e o f d a s t r ia z i n e d e r i v a t i v e s w i t h c e r ta i n

p y r azo l in e d e r iv a t i v es . T h e m ech an i s m in v o lv es s a l t f o r m a t io n w i th am in o g r o u p s

o f t h e p o ly p ep t id e ch a in s i n th e w o o l s t r u c tu r e . In ad d i ti o n t o th i s h y d r o g en b o n d s

a r e a l so f o r m ed d ep e n d in g o n th e s t r u c tu r e o f t h e b r ig h t en e r s .

Th e go ods are t rea ted w i th a so lu t ion con ta in ing 0 .02 to 0 .2% f luorescen t b r igh t -

en in g ag e n t an d 2 - 4 % ace t ic ac id (4 0%) o r 1 -2 % f o r m ic ac id (85 %) to m a in t a in t h e

p H o f t h e ex h au s t b a th 3 t o 5. T h e t r ea tm en t t im e i s ab o u t 2 0 ra in a t 4 0~ A f in a l

r i n s in g w i t h w a t e r c o m p l e t e s t h e p r o c e s s.Op t i ca l b r i g h t en e r s a r e o f t en ap p l i ed t o w o o l w i th a r ed u c t iv e b l each e r u n d e r

ac id o r a lk a l i n e co n d i t i o n s . W o o l a f t e r p e r o x id e b l each in g , a r ed u c t iv e b l ea ch in g i s

ca r r i ed o u t f o r 1-3 h a t 5 0 - 5 5 ~ d u r in g w h ich o p ti ca l b r i g h t en in g ag en t m ay b e

ad d ed . I t i s u s u a l l y ad d ed i n to t h e n eu t r a l r ed u c in g b a th a f t e r 75 % o f t h e r ed u c t io n

t im e . Wh en a l l t h e d i t h io n i t e h as b een co n s u m ed , a 2 % f o r m ic o r ace t i c ac id i s

ad d ed t o co m p le t e t h e ex h a u s t i o n o f t h e w h i t en in g ag en t . B r ig h t en in g i n an ac id

b a th a lo n e d o es n o t g iv e m u ch g o o d r e s u l t s .

T h e m a i n p r o b l e m o f w o o l i s i ts c r e a m y c o l o u r a n d y e l l o w i n g o n e x p o s u r e t o

s u n l ig h t . Bo th t h e b l eac h in g an d f l u o r e s cen t b r ig h t en in g o f w o o l acce l e r a t e t h e

p h o t o - y e l l o w i n g a n d a l s o p h o t o - t e n d e r i n g [ 11 ] . T h e s e y e l l o w i n g a n d t e n d e r i n g o f

w o o l h av e b een s h o w n to d ep en d o n t h e s p ec t r a l d i s tr i b u t io n o f l i g h t (a f f ec t ed b y

g la s s e tc . ), t h e p H [1 2 ], t h e m o i s tu r e c o n t en t o f w o o l , t h e tem p er a tu r e [ 13 ] an d t h e

n a tu r e o f ch em ica l p r e - t r ea tm en t [ 1 4 ]. P h o to - t en d e r in g i s cau s ed b y o x id a t i v e an d

h y d r o ly t i c c l ea v ag e o f t h e p r o t e in ch a in s an d t h e d i s u lp h id e b o n d s [1 5 ]. T h e an -

io n ic d eg r a d a t i o n o f p r o t e in f i b r e s h as b een a s s o c i a t ed w i th p h o to ch e m ica l r eac -t i o n s o f th e t r y p to p h an , h i s t id in e an d t y r o s in e r e s id u es [ 1 6, 1 7 ] . T h e f l u o r e s cen t



328 Opt i c a l B r igh te n ing A ge n t s

b r igh te n ing a ge n t s p r e se n t on the f ib r e a bso r b uv l igh t a nd thus a c c e le r a t e s the

y e l l o w i n g . T h e c h e m i c a l s t ru c t u re s o f c h r o m o p h o r e s f o u n d d u r in g p h o t o - y e l l o w -ing ha ve be e n r e por t e d , w i th a m ino a c id d i ty r os ine be ing ide n t i f i e d on i r r a d ia t e d

wool [18 , 19 ] .

A n u m b e r o f c h e m i c a l t r e a t m e n t s h a v e b e e n s u g g e s t e d t o r e d u c e t h e p h o t o -

y e l l o w i n g o f b l e a c h e d a n d w h i t e n e d w o o l . T e t ra k i s h y d r o x y m e t h y l p h o s p h o n i u m

c h lo r ide , t h iou r e a ( a lone o r a s a f o r m a lde hyde c onde nsa te ) a nd som e m e r c a p ta ns

a nd r e duc in g a ge n t s [20 , 21 ] a nd the r e a c t ion o f woo l w i th su l f a m ic a c id [22] ha ve

be e n show n to o ff e r som e p r o te c t ion a g a ins t pho to - ye l low ing , pa r t i c u la r ly on we t

woo l .

1 0 . 5 . 3 S i l k f a b r i c

I n c on t r a s t t o w oo l , i n s i lk the a c id na tu r e o f the p r o te in i c subs ta nc e ( f ib r ion )

p r e d o m i n a t e s , w h i c h c a n p e r m i t w h i t e n i n g w i t h a c i d a n d b a si c t y p e o f b r ig h t e n i n g

a ge n t s . H ow e ve r , f o r s ilk d i re c t b r igh te n ing a ge n t s a r e p r e f e rr e d .

Af te r de gum m ing o f s i lk , a pe r ox ide b l e a c h ing i s g ive n a nd the b r igh te ne r i s

add ed in the sub sequen t reduc t ive b leaching ba th conta in ing 0 .5 to 4% opt ica l br ight -

ener and 2-5 g /1 redu c ing a gen t and t rea ted for 45 rn in a t 70~ Th en the pH o f theba th i s a d jus t e d to 3 .5 w i th f o r m ic a c id a nd the t r e a tm e n t i s c on t inue d f o r a bou t 15

r a in , r in se d w a r m a nd c o ld .

S i lk is ge ne r a l ly b r igh te ne d by e xh a us t m e tho d be c a use h ighe r de g r e e o f wh i t e -

ne s s c a n be o b ta ine d in th i s c a se tha n by pa dd ing m e thod . I n the pa dd ing m e thod ,

f a b r ic i s pa d de d wi th a so lu t ion o f 5 to 20 g /1 o f op t i ca l b r igh te n ing a ge n t a long

wi th 1 g /1 we t t ing a ge n t a t r oom te m p e r a tu r e , sque e z e d to a ppr ox im a te ly 10 0%

pic k - up a nd the n d r i e d a t 10 0 to 120 ~

L ike w oo l , ye l low ing i s al so a p r ob le m w i th s ilk. F luo r e sc e n t b r igh te n ing a ge n t

a c c e le r a t e s the pho to - d e gr a d a t ion o f s ilk , r e su l t ing in g r e a te r ye l low ing a n d lo s se s

in s t r eng th , e spe c ia l ly in the p r e se nc e o f m o i s tu r e [23 - 25 ] .

1 0 . 5 . 4 P o l y e s t e r f a b r i c

Polye s t e r f ib r es ha ve n o a f fin i ty f o r the w a te r so lub le op t i c a l b r igh te n ing a ge n t s

a nd thus w a te r i n so lub le c om pou nds a re a pp l i e d to po lye s t e r f r om d i spe r s ion in the

sa m e m a nn e r a s d i spe r se dye s by the f o r m a t ion o f a so l id so lu t ion in the f ib r e.

The se b r igh te ne r pa r t i c l es p e ne t r a t e in to the f ib re in a s t a te o f m o le c u la r d i spe r s iona nd the y a r e he ld in the f ib re by Va n de r W a a l ' s f o r c e s . A pa r t o f t he f ine ly d i s -



Op t i ca l B r ig h t en in g Ag en t s 3 2 9

p e r s ed p a r t i c l e f o r m s a m o lecu l a r s o lu t i o n i n t h e b a th . On ly th i s p r o p o r t i o n w h ich

h as d i s s o lv e d i n t h e b a th p en e t r a t e s i n to t h e o u t e r lay e r o f t h e p o ly es t e r , f r o mwhere i t d i f fuses s lowly in to the in te r io r o f the f ib re . Di f fus ion wi th in the in ter io r

o f th e f i b r e i s e s s en t i a l l y a f u n c t i o n o f t h e t em p e r a tu r e a n d t h e co n ce n t r a t i o n o f th e

b r ig h t en e r i n t h e i n t e r fac i a l zo n e .

In ca r r i e r m e th o d o f ap p l i ca t i o n b y ex h au s t p r o ces s t h e p o ly es t e r f ab r i c i s en -

t e r ed i n to a b a th co n t a in in g 0 .5 t o 2 . 0% o p t i ca l b r i g h t en in g ag en t , 1 g/1 d i s p e r s in g

agen t , 2 -4 g/1 su i tab le c ar r ie r and ace t ic a c id to m ain ta in the pH arou nd 5 to 6 . The

g o o d s a r e r u n t h r o u g h th e s o lu ti o n a t 4 0~ f o r 15 t o 30 m in , t h e tem p er a tu r e o f t h e

b a th i s t h en r a i s ed t o b o i l i n g i n 3 0 m in , an d t h e t r ea tm en t i s co n t in u ed f o r a t l e a s t

90 - 1 2 0 m in a t t h e b o i l . Co m p o u n d s s u ch a s d ip h en y l an d ch lo r in a t ed h y d r o ca r -

b o n s a r e s u i t ab l e ca r r ie r s . T h e g o o d s a r e t h en r in s ed w i th h o t w a t e r an d d r i ed .

In th e t h e r m o f ix a t i o n p r o ces s t h e f ab r ic i s p ad d ed w i th 5 - 2 5 g /1 d i l u te s u s p en -

s i o n o f o p t i c a l b r i g h t e n i n g a g e n t a t r o o m t e m p e r a t u r e w i t h a l i q u o r p i c k - u p o f

ap p r o x im a te ly 5 0%, d r i ed at ab o u t 1 2 0~ in an o p en s t en t e r an d th en h ea t ed f o r

3 0 - 60 sec at 1 90- 2 00~ F in a l l y , t h e g o o d s a r e w a s h ed an d d ri ed . T h i s p r o ce s s

m ak es p o s s ib l e h ig h e r t h o r o u g h p u t o f m a te r i a l w i th s u p e r io r d im e n s io n a l s t ab il it y .In t h e p ad - s t eam p r o ce s s t h e g o o d s a f t e r p ad d in g w i th a l i q u o r p i ck - u p o f ab o u t

80% are s tea m ed a t 100-101 ~ fo r 2 -3 h o r und er p ressu re (1 -1 .5 k g /c m 2) fo r 25-

3 0 m in . A l t e r n a t i v e ly , t h e g o o d s m ay b e th e r m o f ix ed b y s u p e r h ea t ed s t eam a t 1 5 0 -

170~ for 3-5 m in.

1 0 . 5 . 5 N y l o n f a b r i c

Op t i ca l b r ig h t en in g ag en t s o f ac id d y e in g t y p e a r e ap p l i ed to n y lo n f r o m an ac id

b a th . D i r ec t co t t o n d y e in g t y p e o f b r ig h t en e r s v a r y i n t h e ir a f f in i t y f o r p o ly am id e s .

C a t i o n ic o p t ic a l b r i g h t e n e r s s h o w a f fi n it y a t lo w t e m p e r a t u r e , b u t m a x i m u m y i e l d

an d f a s tn es s is n o t d ev e lo p ed b e lo w 70~ [2 6] . T h e d i s p e r s e o p ti ca l b r i g h t en e r s a r e

ap p l i ed t o n y lo n a t b o i l i n p r e s en c e o f d i s p e r s in g ag en t (0 . 5 - 1 % ) a t p H 5 t o 6 . T h e y

ex h ib i t b e t t e r l i g h t f a s m e s s (3 -4 ) an d w a s h f as m es s (4 -5 a t 60~ th en ac id d y e ty p e

o f b r i g h t e n e rs .

W i th ac id d y e in g t y p e , t h e g o o d s a r e tr ea t ed o n j i g g e r s o r w in ch b ec k w i th a

s o lu t i o n co n t a in in g h ig h a f f i n i ty t y p e b r ig h t en e r s (0 .05 t o 0 . 5 %) an d ace t i c o r f o r -

m ic ac id (p H 3 . 8 to 4 .5 ) a t 4 0~ f o r 1 0 m in an d t h en th e t em p e r a tu r e i s r a i s ed t ob o i l i n 1 5 m in an d t h e t r ea tm en t i s co n t in u ed f o r 3 0 m in . T h e g o o d s a r e r i n s ed an d



330 Opt i c a l B r igh te n ing Age n t s

d r ie d . T he l igh t f a sm e ss o f the a n ion ic p r od uc t i s o f t he o r de r o f 1 - 2 bu t ye l low ing

doe s no t oc c u r a s in wo o l f ib re . Ny lo n c a n be b r igh te ne d by the hydr ose t t ing p r o -c e s s in HT e qu ipm e n t . The ba th i s s e t w i th 0 .2 - 2% op t i c a l b r igh te n ing a ge n t , 0 .5%

sod ium hy dro sulp hite , 0 .1-0 .5 g/1 sequ ester ing ag ent and 0 .5 g/1 surface act iv e agent .

Th e b le a c h e d g oods a r e t r e a t e d at 40 ~ f o r 10 m in a nd hyd r ose t t ing is c a rr i e d ou t

for 15-20 ra in a t 120-130~ (120~ for ny lon 6, 130~ for ny lon 6, 6 ). Th e t rea t -

m e n t l i quor i s c oo le d to 8 0- 8 5~ a nd the n the goods a r e r in se d a nd d r ie d . The

im p r ove d l igh t ( = 3 ) a nd wa sh ( ~ 5 ) f a s tne s s c a n be ob ta ine d .

S e le c t e d a c id a nd d i spe r se type o f op t i c a l wh i t e n ing a ge n t s c a n be a pp l i e d to

ny lo n by c o n t inuou s o r s e m i - c o n t inuou s p r oc e ss . I n the pa d - r o l l p r oc e s s , f a b ri c is

pa d de d w i th 10 - 20 g/1 op t i c a l b r igh te n ing a ge n t s at 50 -7 0 ~ wi th pa dd ing m a ng le

e xp r e s s ion a t 60 - 7 0 % a nd the n ke p t i n a c ha m be r f o r 1 -2 h a t 9 0~ Ac id c ond i -

t ions a r e m a in ta ine d by a dd ing a m m on ium c h lo r ide in the pa d - ba th so lu tion . I n the

p a d - s t e a m p r o c e s s , th e p a d d e d g o o d s a re s t e a m e d f or a b o u t 3 m i n a t a s t e am i n g

te m pe r a tu r e o f 10 5~ I n the a c id - sho c k p r oc e ss , t he f a b ri c a f te r pa dd ing wi th c o ld

so lu t ion c o n ta in ing b r igh te ne r s a r e the n t r e a te d in a bo i l ing ba th c on ta in ing f o r m ic

a c id in a n ope n wid th soa pe r , wa she d a nd d r i e d . C e r t a in a c id type b r igh te ne r s( py r a z o l ine s a nd 1 : 2 : 3 tr i a z o le s ) c a n be a pp l i e d to po lya m ide by the the r m oso l

pro cess a t 170-190~ Hea t fas tness dur ing hea t t r ea tm ent and f ixa t ion , how ever , is

m e d i u m .

10 .5 .6 P o l yacr y l on i t r i l e f ab r i c

The a c r y l i c f ib re s a r e no r m a l ly w h i t e , bu t va r i a t ions in de g r e e o f ye l low ne ss

a nd s t a b i l i t y to the r m a l de g r a da t ion wi th f ib r e s f r om d i f f e r e n t sou r c e s c a n be

m i n i m i s e d b y a p p l ic a t io n o f w h i t e n in g a g e n t s [ 2 7, 2 8] . T h e N e o c h r o m e p r o c e s s

invo lve s a pp ly ing b r igh te ne r du r ing the ge l s t a ge o f f ib r e p roduc t ion . T hou gh c h lo -

r i t e b l e a c h ing r e m ove s ye l lowne ss bu t c e r t a in f ib r e s suc h a s C our t e l l e c a nno t be

b le a c he d wi th c h lo r i t e be c a use o f subse que n t de g r a da t ion o f the f ib r e . Fu r the r -

m or e , t he na tu r e o f c opo lym e r a l so de te r m ine s the a f f in i ty o f f ib r e f o r va r ious

op t i c a l b r igh te ne r s . M os t ly , po lya c r y lon i t r i le c o n ta in ing a n ion ic g r oups c on f e r s a n

a f f in i ty f o r c a t ion ic type o p t i c al b r igh te ne r s . The se type s o f b r igh te ne r s h a ve e i the r

a he te r oc y c l i c n i t r oge n o r e x te rna l a m ino g r oup wi th c a t ion ic c ha r a c ter .

I n the e x ha us t m e thod , t he f ib r e m a te r i a l i s in t r oduc e d in to a ba th c o n ta in ingc a t ion ic b r igh te n ing a ge n t a nd 3 - 5% f o r m ic a c id ( 8 5%) to m a in ta in the pH 3 to 4 at



Op t i ca l B r ig h t en in g Ag en t s 331

ab o u t 70~ T h e l i q u o r i s t h en b r o u g h t t o t h e b o i l in 30 m in an d h e ld a t t h a t t em -

p e r a tu r e f o r a f u r th e r p e r io d o f 3 0 m in . T h e b a th i s f in a l l y co o l ed an d t h e m a te r i a l

i s w as h e d o r ri n s ed .

The one ba th tw o s tage b leach ing and br igh ten ing o f acry lic f ib res i s qu i te popular .

In th i s p r o ced u r e , t h e m a te r i a l i s b o i l ed w i th ch lo ri t e , u s in g o x a l i c ac id a s an acce l -

e r a to r f o r ab o u t 3 0 m in , t h e b a th is co o l ed t o 80~ an d ex ces s ch lo r in e i s e l im i -

n a t ed w i th s o d iu m h y d r o s u lp h i t e . In th e s eco n d p h as e , t h e o p ti ca l b r ig h t en in g ag en t

i s ad d e d an d t h e b a th i s ag a in h ea t ed t o t h e b o il i n 3 0 m in an d t h e m a te r i a l i s t r ea ted

a t t h i s tem p er a tu r e f o r fu r th e r 3 0 m in . T h e m a te r i a l i s t h en w o r k e d u p i n t h e u s u a l

m an n e r .

N o n - io n i c b r ig h t en in g ag en t can a l s o b e t ak en u p b y th e f i b re f r o m s u s p en s io n s .

T h e f i b r e m a te r i a l i s t r ea t ed w i th a s o lu t i o n co n t a in in g d i s p e r s e t y p e b r ig h t en e r s

an d 2 % f o r m ic ac id (85 %) (p H 3 t o 4 ) at 1 00~ f o r 3 0 t o 4 0 ra in . E x h au s t i o n can

b e acce l e r a t ed b y r a i s i n g t h e t em p e r a tu r e o f t h e b a th t o 1 1 0~

T h er e a r e ce r t a in t y p e o f ac r y l i c f i b r e s t h a t can b e w h i t en ed b y p ad d in g t ech -

n i q u e s . T h e t h r e e m e t h o d s o f p a d d i n g a re p a d -r o ll , p a d - s t e a m a n d a c i d - s h o c k p r o -

ces s . In t h e p ad - r o l l p r o ces s , t h e f ab r i c i s p ad d ed w i th a s o lu ti o n co n t a in in g o p t i ca lb r ig h t en in g ag en t , f o rm ic ac id, d i s p e r s in g ag en t an d t h i ck en in g ag en t , a t r o o m t em -

p e r a tu r e t o a m an g le p i ck - u p o f 80 - 85 %, b a t ch ed , s t o r ed o n r o l l in a ch am b er s e t a t

1 00 -1 05 ~ f o r 2 h . In t h e p ad - s t eam p r o ces s , t h e p ad d ed f ab r i c i s s t eam ed in a

sa tu ra ted s team for 5 m in a t 105~ In the ac id shock process , the f luoresc en t b r igh t -

en in g ag en t s a r e ap p l i ed t o t h e m a te r i a l b y m ech an ica l p i ck - u p an d w h i t e i s d ev e l -

o p ed b y ac id t r ea tm e n t i n a sep e r a t e b a th .

10 .5 .7 Ca t i on i c dyea b l e po lye s t er f abr i c

Cat io n i c d y eab l e p o ly es t e r p o s s es s es an io n i c g r o u p an d h en ce ca t i o n i c b r ig h t -

en e r s can b e ap p l i ed a s i n th e ca s e o f ac r y l ic f ib r e s . Ho w e v er , t h e e f f ec t o f ca t i o n i c

b r ig h t en e r s o n ac r y l i c f ib r e s can n o t b e r ep r o d u ced o n an io n i ca l l y m o d i f i ed p o ly e s -

t e r [ 2 9 ] . T h i s p r o v es t h e f i b r e - b r ig h t en e r i n t e r - r e l a t i o n s h ip . D i s p e r s e b r ig h t en e r

can a l s o b e ap p l i ed t o ca t io n i c d y e ab l e p o ly es t e r . T h e o p t i ca l b r i g h t en in g ag en t can

b e a p p l i ed t o ca t i o n i c d y eab l e p o ly es t e r i n a ch lo r it e b a th . T h e b r ig h t en e r s a r e ap -

p l i ed a t 98~ in p r e s en ce o f ca r r i e r b as e d o n d i ch lo r o p h en y l o r b ip h en y l . Su i t ab l e

b r ig h t en e r s a r e ch lo r i t e r e s i s t an t t y p es b as ed o n b en zo f u r an y l an d b en zo x azo y l -b e n z i m i d a z o l e . C e r t a i n b r ig h t e n e r s c a n b e a p p l i e d b y th e r m o s o l m e t h o d a t 2 0 0~




S of t d i spe r se b r igh te ne r s c a n be a pp l i e d a t 16 0~ The l igh t f a s tne s s ra t ings o f

c a t ion ic b r igh te ne r s on c a t ion ic dy e a b le po lye s t e r a r e h ighe r tha n on a c r y l ic . Non -ion ic b r igh te ne r s g ive poor r a t ings tha n on no r m a l po lye s t er .

1 0 . 5 . 8 P o l y v i n y l c h l o r i d e f a b r i c

T h e l o w m e l t i n g ty p e s o f P V C p e r m i t a m a x i m u m t e m p e r a tu r e o f 6 0~ d u r in g

op t i c a l b r igh te n in g a nd thus c a r ri e r m us t be use d in the a pp l ic a t ion ba th . The he a t

res is tan t types of PV C can be br ig hten ed e i the r in presence of ca r rie r a t 65 to 75~

or w i thou t c a r r i e r i n a bo i l ing ba th . B r igh te n ing i s ge ne r a l ly done du r ing b le a c h ing

with sodium chlor i te and opt ica l br ighteners , ca r r ie r , d ispe rs ing agent and c ross-

l inking agents a re added in the b leach ba th . The b leaching ba th i s hea ted to 55~

a nd wo r ke d a t t h is t e m pe r a tu r e f o r a bou t 45 m inu te s . T he m a te r i a l i s t he n wa she d

with cold wa te r .

1 0 .5 .9 O t h e r s y n t h e t i c p o l y m e r s a n d p l a s t ic s

The u se o f f luo r e sc e n t b r igh te ne r s in wh i t e n ing o f po lyo le f in s , po lyc a r bona te s

a nd po ly ( m e thy l m e tha c r y la t e ) a r e r e por t e d [30] . The inc r e a s ing d e m a n d f o r m a n y

new appl ica t ion s for p las t ic s and t rends for recyc l ing hav e c rea ted a dem and for the

use of spec ia l opt ica l br ightenin g agent . Long l i f e expec ta t ions for ch i ldren ' s p lay-ing th ings , r e f r ige ra tors and ra inwe ar need a long l i fe of opt ica l br ightenin g ag ents .

N ew s t i lbene de r iva t ives and addi t ion o f s tab i l ise r s improv e the br i l l iance and h igh

long l if e . The se c om poun ds a l so p r e ve n t ye l low ing o f p l a s ti c s du r ing the r m oso l

p r oc e ss ing , g iv ing a be t te r wh i t e ba se d m a te r i a l.

1 0 . 5 . 1 0 B l e n d e d f i b r e f a b r i c s

The po lye s t e r / c o t ton b le nde d f a b r i c s c a n be op t i c a l ly b r igh te ne d to the sa m e

degree of in tens i ty and br i l l iance as pure cot ton fabr ic. Norm al ly , a f te r appl ica t ion

of d isperse type opt ica l br ighteners for poly es te r f ibre , e ithe r by exh aus t ion or pad-

d ing m e thod , t he usua l d i re c t op t i c al b r igh te ne r s a re a pp l i e d to c o tton by e xha us t

m e thod . An in t e rm e d ia t e t r e a tm e n t w i th hydr osu lph i t e i s ne c e s sa r y to r e m ove po ly -

e s t e r b r igh te ne r de pos i t e d m e c ha n ic a l ly on c o t ton po r t ion du r ing pa dd ing ope r a -

t ion . Op t i c a l b r igh te n ing o f po lye s t e r / c o t ton b le nds c a n be c om bine d w i th b le a c h -

ing . In the combined pro icess , the goods a re t r ea ted in a ba th conta in ing 1-5 g /1

sod ium chlor i te a long wi th 0 .5-1 .5% f luo rescent br ighten er (o .w. f .) and ace tic ac id

(pH = 4) a t boi l about an hour . The ba th i s then dra ined and the goods a re g ivent rea tm ent w i th an opt ica l br igh tenin g agen t for co t ton . In the cont inu ous p rocess o f




a pp l i c a t ion , t he b l e nde d f a b r ic s a r e pa d de d wi th a so lu t ion c on ta in ing d i spe r se a nd

c e l lu lose b r igh te ne r s a long wi th d i spe r s ing a ge n t . Af t e r pa dd ing a nd d r y ing , t hewh i t e i s de v e lope d by ba k ing f o r 20 - 30 se c a t 150- 200 ~ The f a b r i c s a r e the n

w a sh e d - o f f w i th d e te r ge n t ( 2 g/ l) a nd soda a sh (1 g / l) at 50 - 60 ~ f o r 15 m in , r in se d

a nd d r i ed . Pa d - s t e a m p r oc e ss c a n be a pp l i e d to po lye s t e r / c o t ton b le nd s in the sa m e

wa y a s f o r 1 0 0 % po ly e s t e r by the inc lus ion o f the pa d ba th o f a su i t a b le c onc e n t r a -

t ion o f a c e l lu lose b r igh te ne r . I n a no the r m e thod , t he op t i c al b r igh te ne r s f o r po lye s -

t e r /c o t ton b le nds m a y be a dde d in the r e s in f in i sh ing ba th . I n th is m e tho d , t he goods

a r e pa d de d wi th a so lu t ion c on ta in ing c r os s - l ink ing a ge n t , c a t a lys t , so f t e ne r , f luo -

r e sc e n t b r igh te n e r f o r bo th po ly e s t e r a nd c o t ton a nd we t t ing a ge n t , d r i e d a nd c u r e d

a t 140 - 150~ f o r 4 - 5 m in . A f ina l s c our ing f o l low e d by wa sh ing p r oc e ss c om p le te s

the p r oc e ss . A l thoug h the p r oc e ss i s e c onom ic a l , the b r igh te n ing e f f e c t s ob ta ine d

a r e no t ve r y in t e nse .

T h e m o s t e f f i c ie n t p r o c e s s f o r o p t ic a l b r ig h t e n i n g o f p o l y e s t e r / w o o l b l e n d e d

f a b r i c s i s t o b r igh te n po lye s t e r c on te n t f i r s t a nd the n b le a c h woo l po r t ion wi th

pe r ox ide a nd b r igh te n the woo l in a r e duc ing b le a c h f o l lowing pe r ox ide ba th . How -

e ve r , the two b a th p r oc e ss i s t im e c onsu m ing . I n one ba th p r oc e ss , t he good s a r et r e a t e d wi th a ba th c o n ta in ing the op t i c a l b r igh te ne r s f o r wo o l a nd po lye s t e r , c a r -

r ie r , d ispe rs ing agen t , a pro tec t ive agen t for w ool an d ace t ic ac id (pH ~- 5) a t 95-

10 0~ f o r 20 - 30 m in , c oo le d the ba th , r in se d a nd w a she d w i th non - ion ic de te r ge n t

( 2 -3 g / l ) a t 40 - 45~ f o r 15 to 20 m in . How e ve r , t he one ba th p r oc e ss su f f e r s f r om

the d i sa dv a n ta ge o f poss ib l e s t a in ing o f the w oo l by the c a r r i er a nd po lye s t e r b r igh t -

e n e r n o t b e i n g r e m o v e d b y a s i m p l e s c o u r.

T h e b l e n d s c o n t a i n i n g p o l y a m i d e / c e ll u l o s e c a n b e o p t i c a ll y b r i g h t e n e d w i t h a

so lu t ion c on ta in ing se l e c t e d c e l lu lose b r igh te ne r s by a d jus t ing the t e m pe r a tu r e a nd

pH o f the a pp l i c a t ion ba th . The b r igh te ne r s w h ic h sho w l i tt le c ha ng e in up ta ke on

ny lon by c ha nge in pH shou ld be se l e c t e d . L ike wise , r a i s ing the t e m pe r a tu r e in -

c r e a se s the up ta k e on the ny lon r e l a t ive to c e l lu lose . Th e t e m p e r a tu r e o f the ba th i s

r a i se d to 9 5 - 10 0 ~ ove r 30 m in a nd the f a b ri c is t r e a t e d fo r 30 -40 m in a nd the n

r inse d w e l l a nd d r i e d .

F o r p o l y a m i d e / w o o l b l e n d e d f a b ri c s f lu o r e s c e n t b r i g h t e n i n g a g e n t s ( 1 - 2 % ) a r e

a pp l i e d f o l lowin g hyd r oge n p e r ox ide b l e a c h ing in p r e se nc e o f s t a b i li s e r (3 - 5 g / l) .The t r e a tm e n t i s c a r r i e d ou t a t 7 0 -7 5~ f o r 45 - 6 0 m in a nd the n r in se d a nd d r i e d .




For b r igh te n ing o f a c r y l i c /c e l lu lose f ib r e b l e nde d f a b ri c s the c om pa t ib i l i t y o f

the b r igh te ne r s f o r e ac h f ib r e is m os t im p or t a n t. I f t he two c l a sse s o f b r igh te ne r s

a r e no t c om p a t ib l e , t he n a two- ba th p r oc e ss i s ne c e s sa r y , f ir s t a pp ly ing the a c r y li c

br ig hten er and , then in a f resh ba th the ce llu lose br ightener . Pe ro xide /hy poc hlor i te

b le a c h ing o f a c r y l i c / c o t ton o r c om bine d b le a c h ing t e c hn ique s c a n be use d . C h lo -

r i te s t a b le p r oduc t s shou ld be a pp l ie d f r om the b l e a c h ba th . Ano the r r e qu i r e m e n t i s

we t l i gh t f a s tne ss in p r e se nc e o f pe r bo r a t e c o n ta in ing wa sh ing a ge n t s. Ga r m e n t s

m a de f r om PAN or the ir b l e nds on d r y ing in sun , af te r wa sh ing wi th wa sh ing pow -

de r s c on ta in ing pe r bor a t e , a r e obse r ve d to show ye l lowing .

For a c r y l i c /woo l b l e nds , t he a c ry l i c po r tion i s b r igh te ne d in the no r m a l wa y a nd

the n the woo l i s b l e a c he d w i th hydr oge n pe r ox ide a nd subse que n t r e duc t ion b le a c h -

ing i s done in a ba th c on ta in ing su i t a b le b r igh te ne r ( 1 - 2%) a nd s t a b il i s e d sod ium

hy dro sulp hi te (3-5 g / l ) a t 85~ for 30 ra in . The fabr ic i s then r insed and dr ied .

For po lya m id e / a c r y l i c b l e nds , bo th the f ib r e s c a n be b r igh te ne d by u s ing su i t-

ab le d isperse type br ightene rs a t 95-98~ for 30-60 ra in , cooled , r insed we l l and

dr ied . W her e b leach ing i s necessa ry , a su i tab le br ighten er s tab le to ch lor i te m ay be

inc lude d in the b l e a c h ba th .

R E F E R E N C E S

1 E . S. O l s on , T e x t i l e W e t P r oc e sse s ,Vo l I , No ye s Pub . , Pa r k R idge , Ne w Je r -

sey , USA (1983) p 153.

2 E . W e b e r , M e l l i a nd Te x t i lbe r. , 35 (19 54) 20 4 .

3 D.A.W. Adams, J . Soc . Dyers . Colour is t s , 75 (1959) 22 .4 M i l lo~ Z a h r a dn ik , The P r oduc t ion a nd App l i c a t ion o f FB A s , John W i le y &

Sons , Chiches te r , Sussex (1982) p 14 .

5 E . Al len , J . Opt . Soc . Am. , 47 (1959) 22 .

6 D. A.W . Adam s, J. Soc . Dye rs Colour is t s , 75 (1959) 933.

7 D. A.W. A dam s, J. Soc. Dyers Colou r is t s , 77 (1961) 670.

8 T . H. Ma r t in i and H. Probs t , Me l l iand Te xt i lbe r . , 65 (1984) 627.

9 A. E . S i eg r is t , H. Hef t i , H. R . M eye r and E. Schmidt , Rev. Prog. Color . , 17

(1987) 39.

10 T. H. Mar t in i , C hem ifase rn / Tex t i l indus t r ie (CTI) , 38 /90 (1988) 827 .




11 P . A. Duf f ie ld and D. M. Lew is , Rev. Prog. Color . , 15 (1985) 38 .

12 W . S. S im psion , J. Tex t i le Ins t ., 78 (19 87)4 30 .13 R . Leve n, Tex t i le Res . J. , 55 (1985) 477.

14 D . J . Tuc ke r a nd C . S . Whe we l l , P r oc . I n t . Wool Te x t . R e s . C onf . , Aa c he n

(1977) 590 .

15 L .A . H ol t and P . J . W ate rs , Proc . In t . W ool Text . Res . Con f . , To kyo . , 1985 IV.

16 L . A. Hol t , B . Mil l ige n , W . E . Savige , J. Tex t i le Ins t . , 63 (3) (1977) 124.

17 L .H . L e a ve r a nd G. C . R a m sa y , Pho toc he m ic a l a nd Pho tob io logy , 9 ( 6) ( June

1996) 531.

18 K. Rooper , Mel l iand Text i lbe r . , 65 (1984) 812.

19 L . H. Leav er , R . C . Mars ha l l an d D. E . R ive t t , Proc . In t. W oo l Text . Res . J .,

44 (1974) 846 .

20 L . A. Hol t , B .M il lge n and L . J . W olf ram , Text i le Res . J ., 44 (1974) 846 .

21 R . S .Da vidso n, G. M. I smai l and D. M. Lew is , J . Soc . Dy ers Colo ur is t s , 103

(1987) 308.

22 M . Pa i l th r ope a nd B . C a m or on , J . Pho toc h e m . , 37 ( 19 8 7 ) 39 1 .

23 R . S . Da vid son , G. M. I sma i l and D. M. Lew is , J . Soc . Dy ers Co lour is t s , 101(1987) 261.

24 P . A . Duf f i e ld a nd D . M . L e wis , R e v . P r og . C o lo r & R e la t e d Top ic s , 10 4

(1985) 477 .

25 R . Leven , Te xt i le Res . J. , 55 (8) (1985) 477 .

26 W i l l i a m so n , M a n- m a de Te x t i l e s , 39 ( 19 6 2) 40 & 55 .

27 R o sc h , M e l l i a nd Te x t i lbe r I n t e m a t . , 50 ( 19 6 9) 19 9.

28 De c or t e , Te x t i l e s C h im ique s , 27 ( 4 ) ( 19 7 1) 4 .

2 9 S i e h e a n c h . , R . A n i l k e r , H . H e f t i , A . R a u c h l e a n d M . S c h l a p f e r ,

Text i lve redlung, 11 (1976) 369 .

30 E. Esch le , P las tv e rabe i te r , 21 (1970) 629.



Chapter 11

C O M B I N E D P R E - T R E A T M E N T P R O C E S S E S O F T E X T IL E S

1 1 .1 I n t r o d u c t i o nN o w - a - d ay s a ll e f fo r t s i n t h e f i e ld o f p r e - t r ea tm en t p r o ces s es o f tex t i le s a r e

d i r ec t ed t o w ar d s s h o r t en in g an d s im p l i f ica t i o n o f t h e t r ea tm en t . In t h e co n v en -

t i o n a l p r ep a r a t i o n , t h e d es i z in g , s co u r in g an d b l each in g p r o ces s es a r e ca r r i ed o u t

s ep e r a t e ly a t h ig h t em p er a tu r e s , r eq u i r i n g t h e u s e o f l a r g e am o u n t o f t h e r m a l en -

e r g y . I n o r d e r t o m i n i m i s e e n e r g y c o n s u m p t i o n i t h a s b e c o m e n e c e s s a r y t o c o m -

b in e s ev e r a l p r e - t r ea tm en t s t ag es b y r ed u c in g n u m b er o f o p e r a t i o n s o r b y s h o r t en -

in g t h e r eac t i o n t im e . Al th o u g h s ev e r a l n ew p r o ces s es an d s o m e co n t in u o u s an d

s em i - co n t in u o u s m a ch in e r i e s h av e b een d ev e lo p ed , t h e i d ea l o f a t r u e ly s i n g le s t ag e

p r o ces s em p lo y in g o n ly o n e d es i z in g cu m b l ea ch in g s t ag e su i t ab le f o r a ll q u a l it i e s

o f c lo th an d en d u s es , h a s n o t b een d ev e lo p ed s o fa r . P r o ces s i n t eg r a t i o n t o en ab l e

in t eg r a t ed d es i z in g / s co u r in g , s co u r in g / b l each in g o r d es i z in g / s co u r in g / b l each in g

c o n t i n u e s b y b o o s t i n g t h e c h e m i c a l r e c i p e t o i m p r o v e t h e r e m o v a l a n d

d eco lo u r i s a t i o n o f im p u r i t ie s . Lo w e n e r g y ch em ica l p r e -t r ea tm en t o f t ex t il e s u s in g

h ig h e r co n cen t r a t i o n s o f ch em ica l s i n o r d e r t o i n t eg r a t e t h e p r o ces s es can w o r k

w e l l i f t h e p r o ces s i s ca r e f u l l y co n t ro l l ed . M an y m e th o d s h av e b een r ep o r t ed an d an u m b e r o f l o w t e m p e r a t u r e (2 5 -4 5 ~ b a t c h sc o u r in g a n d b l e a c h i n g p r o c e s s e s ar e

ava i lab le [ 1 -10] co m bin in g tw o or a ll the th ree s tages in to two s tage o r s ing le s tage

p r o ces s . In al l t h e s e acce l e r a t ed p r o ces s es , co s t s av in g s a r e o b t a in ed i n s team ,

w a te r , e l ec t r i c i t y an d l ab o u r w i th l i tt le i n c r eas e i n ch em ica l co s ts . T h e b r i e f ac -

co u n t g iv en i n th i s ch ap t e r a im s a t p r e s en t in g a b i r d ' s ey e v i ew in t h e a r ea o f co m -

b in ed p r e - t r ea tm en t p r o ces s es .

1 1 .2 C o m b i n e d S c o u r i n g a n d D e s i z in g

M a n y c o m b i n e d s c o u r in g a n d d e s i z i n g p r o c e s se s a r e d e v e l o p e d b u t th e s e p r o -

cesse s a re par t ic u lar ly usefu l i f the s izes a re no t in tended to be r eco vere d [11-13 ] .

A l k a l i n e h y d r o g e n p e r o x i d e s a n d p e r o x y c o m p o u n d s s u ch a s p e r s u l p h a t e ,

p e r p h o s p h a t e , p e r o x y d ip h o s p h a t e can b e u s ed as o x id a t i v e d es i z in g ag en t an d fr ee

r ad i ca l s a r e p r o d u ced f av o u r in g s ize d eg r ad a t i o n ra th e r t h an b l each in g . Ho w ev er ,

s o m e b l eac h in g d o es a l s o tak e p l ace u n d e r t h es e co n d i t i o n s.

A c o m b i n a t i o n o f p e r o x y c o m p o u n d a n d c a u st ic s o d a a t e l e v a te d t e m p e r a t u re

can e f f ec t i v e ly co m b in e d es i z in g an d s co u r in g co n d i t io n s . In t h is p r o ces s , th e f ab -



C o m b i n e d P r e - T r e a t m e n t P r o c e s se s o f T e x t i le s 3 3 7

r i c i s t r ea t ed w i th a s o lu t i o n co n t a in in g 0 . 2 % p o ta s s iu m p e r s u lp h a t e an d 4 % s o -

d iu m h y d r o x id e an d t h en s t eam e d in J - Bo x a t 95~ f o r 85 m in , w a s h ed an d d r i ed .T h i s co m b in ed p r o ces s o f co t t o n f ab r i c i s m o r e o r l e s s ad eq u a t e w i th a f l u id i t y o f

about 1 .8 .

In th e p ad - s t eam p r o ces s , t h e f ab r i c i s p ad d ed w i th a s o lu ti o n co n t a in in g 70 g/1

caus t ic soda , 3 g /1 sod ium pe r su lp hate and 10 g /1 non - ion ic d e terg en t a t 40~ w i th

a w e t p i ck - u p o f ab o u t 80% an d th en t h e f ab r i c i s s t eam ed f o r 1 2 r a in a t 1 02 ~

T h e f ab r ic i s th en w as h ed t h o r o u g h ly i n an o p en s o ap e r w i th a t em p er a tu r e o f ab o u t

98~ in the fi r s t and second , 80~ in the th i rd and 60 and 50~ in the four th and

f if th co m p ar tm en t s r e s p ec t i v e ly .

G r e y f a b r ic c a n b e s i m u l t a n e o u s l y d e s i z e d a n d s c o u r e d b y m a k i n g u s e o f a

s u s p en s io n o f en zy m e , a ch lo r in a t ed s o lv en t an d s u r f ac tan t s o lu t i o n (Mar k a l I I p r o -

ces s , Ch a p te r 4 ) .

1 1 . 3 C o m b i n e d S c o u r i n g a n d b l e a c h i n g

S i n g l e s t a g e b l e a c h i n g p r o c e s s e s u s i n g h y d r o g e n p e r o x i d e r e q u i r e s o m e a d d i-

t i o n a l ch em ica l s t h a t can ac t a s ac t iv a to r , s t ab i li s e r, s u r f ac t an t an d s c o u r in g ag en t .

S t r o n g l y a l k a li n e s o l u ti o n o f h y d r o g e n p e r o x i d e h a s b e e n a d v o c a t e d f o r su c h c o m -b i n e d p r o c e s s e s . S o d i u m p e r s u l p h a t e a n d p o t a s s i u m p e r s u l p h a t e b o o s t th e s in g l e

s t a ge o p e r a t io n i n p r e s e n c e o f h y d r o g e n p e r o x id e . O t h e r c o m p o u n d s w h i c h a c c e l -

e r a t e t h e p e r o x i d e r e a c t i o n s a r e u r e a , m e t h y l c a r b o n a t e a n d t e t r a a c e t y l

e th y l en ed i am in e . Ho w e v er , su ch ch em ica l s i n c r ease t h e ch em ica l co s t. Gen e r a l l y ,

in t r ad i t iona l k ie r b leach the cos t o f u t i l i t i es i s near ly 3 .5 to 4 t imes the chemica l

cos t an d in con t inuo us b lea ch i t i s abo u t twice to 2~/2 t ime s the ch em ica l cos t .

A c o m b i n e d p r o c e s s ( A T I R A ) c a n b e c a r r ie d o u t i n a k i e r w i th a b l e a c h l i q u o r

c o n t a i n i n g h y d r o g e n p e r o x i d e ( 5 0 % ) 1 .5 % , s o d iu m h y d r o x i d e 1 .5 % , s o d i u m m e t a

s i li ca t e 1 %, s o d iu m t e t r ap y r o p h o s p h a t e 0 . 5 %, em u l s i f y in g ag en t 0 . 5 % an d w e t t in g

ag en t 0 . 1 % w i th a l i q u o r r a t io o f 2 .5 :1 a t 60~ T h e l i q u o r i s c i r cu l a t ed t h r o u g h th e

m a te r ia l f o r ab o u t 1 2 h . A lo w tem p er a tu r e ca ta ly s t ( " U r j a l " ) d ev e lo p ed b y AT IRA

av o id s t h e u s e o f s o d iu m s i l i ca t e i n t h e b a th an d a l s o b l each in g w i th h y d r o g en

p e r o x i d e m a y b e p o s s i b l e e v e n a t ro o m t e m p e r a t u re .

In an o th e r p r o ces s [ 1 4 ,1 5 ] , th e k i e r c i r cu l a t i o n i s r ed u c ed b y u s in g e m u l s i f ied

s o lv en t s y s tem s (Ch ap te r 4 ). E m u l s i f ied s o lv en t s y s t em co n s i s ts o f b l en d s o f em u l -s i f te r and so lven ts l ike ch lor ina ted hy droca rbon s , m inera l o i l s e tc ., w hich s tab i l i ses





C o m b i n e d P r e - T r e a t m e n t P r o c e s se s o f T e x t i le s 3 3 9

T A B L E 1 1 . 1

R e c i p e s f o r C o m b i n e d S c o u r i n g a n d B l e a c h i n g

Rec ip e I Re c ip e I I

Im p r eg n a t io n F eed l i q u o r Im p r eg n a t io n F eed l i q u o r

Ingrad ien ts l iquor (m l / 1 ) ( r e - in forced l iquor (ml/1) (ml/1)

3 .5 t imes)

(ml/1)

H202(35% ) 30 105 70 105

N aO H (3 6~ ') 2 0 70 2 2 77So d iu m s i li ca t e

(38~ ') 8 28 - -

San d o p a n SF 1 2 4 2 - -

(w e t t i n g ag en t )

San d o p a n C BN l iq . - - 4 1 4

Sta bi l ise r SIF l iq . - - 8 28

M ag n es iu m Ch lo r id e 0 .3 0 . 4 0 . 4 0 . 4

em u l s i f i ed s o lv en t (p en t ach lo r o e th y l en e ) b as ed s co u r in g ag en t (2 %) at 3 0~ an d

b a t ch ed f o r 6 - 8 h an d t h en w as h ed .

11 .4 Combined Des i z ing , Scour ing and B leach ing

M a n y c o n t i n u o u s p r o c e s s i n g m a c h i n e r i e s h a v e b e e n d e v e l o p e d o v e r t h e p a s t

f ew d ecad e s b y w h ich co t t o n an d p o ly es t e r / co t t o n b l en d e d f ab r i c s can b e d es i zed ,

s co u r ed an d b l each ed i n o n e s in g l e o p e r a t io n .

A s A S I S A s h o c k s y s t e m f o r c o n t i n u o u s d e s i z i n g , s c o u r i n g a n d b l e a c h i n g i n

o p e n w i d t h g i v e s r e s u l t w i t h i n f e w m i n u t e s w i t h o u t a n y n e e d f o r p r e v i o u s p a d -

b a t ch p r o c es s . T h e r eac t i o n t im e i s o n ly 2 m in .

D u P o n t h a s d e v e l o p e d a 2 m i n b l e a c h i n g p r o c e s s f o r h e a v y f a b ri c s u s i n g H202a t s p ec i f ic p H v a lu e em p lo y in g a s p ec i a l fo r m u la t i o n to p r ev en t u n d u e d eco m p o s i -

t i o n o f p e r o x id e an d d am ag e t o t h e f ab ri c u n d e r p r o ces s .

IT CO p r o ces s d ea l s w i th a s i x s ec t i o n ed J - Bb o x s y s t em an d t h e t r ea tm en t i s

co n t in u o u s w i th co m p le t e s a tu r a t i o n an d co u n te r - cu r r en t f l o w o f w a te r .

T h e F a r m e r - N o r t o n s t e a m - p u r g e s y s t e m is e x t r e m e l y e f f e c ti v e i n p r o m o t i n g ath o r o u g h s a tu r a t i o n o f t h e f ab ri c w i th ch em ica l p r e - t r ea tm en t l i q u o r s .



3 4 0 C o m b i n e d P r e - T r e a t m e n t P r o c e s se s o f T e x t il e s

In th e v ap o r lo c m ach in e f u ll b l each in g can b e o b t a in ed i n o n e p as s ag e o f 90 to

120 sec dura t ion a t a t em pera tu re o f 134~ (30 p . s . i. ) .T h e I C I M a r k a l I II p r o c e s s c o m b i n e s b l e a c h i n g w i t h s c o u r in g a n d d e s i z in g b y

u s i n g a n e m u l s i o n o f a q u e o u s H202 n t r ich lo r o e th y l en e - s u r f ac t an t s o lu ti o n , f o l -

l o w e d b y s t e a m i n g a n d w a s h i n g -o f f .

An ex am p le o f l a t e s t p r ep a r a to r y e q u ip m en t f o r o n e s t ep d es i z in g , s co u r in g an d

b leach in g i s t h e Reco - Y e t f r o m Ram is ch K le in ew ef e r s [ 1 8, 1 9 ] . W i th th e Rec o - Ye t

a h ea t ed ae r o s o l o f s t eam an d ch em ica l s , i n c lu d in g a n ew m u l t i - f u n c t i o n a l au x i l -

i a r y ag en t an d t h e r m a l en e r g y , i s ap p l i ed t o th e f ab r i c s im u l t an eo u s ly i n a r eac t i o n

t im e o f o n e t o t h ree m in u t e s .

B e n n i n g e r h a s d e v e lo p e d " B e n - B l e a c h - S y s t e m " f or d e s iz in g , s c o u ri n g a n d

b leac h in g i n o n e o p e r a t io n . T h e s y s t em co m p r i s e s f o u r m o d e l s : Be n - In j ec t a f o r

d e s i z in g , B e n m - I m p e c t a f o r i m p r e g n a t io n , B e n - S t e a m a n d B e n - E x t r a c ta f o r w a s h -

in g . W i th t h e a id o f i n d iv id u a l d i s p en s in g s y s t em , t h e feed - t o each m o d u le - o f

ch em ica l can b e co n t r o l l ed . In t h e s t eam er , t h e t i g h t - s t r an d f ab r i c i s p l a i t ed o n a

r o l l e r - b ed p e r m i t t i n g a d w e l l t im e o f 1 - 60 m in .

In th e F l ex n ip (Ku s t e r s ) co t to n f ab ri c can b e p r o ces s ed b y a s i n g l e s t ag e p r o ces san d a r ed u c t io n i n en e r g y an d w a te r u s ed i s c l a im ed .

Dip - Sa t V ar io u n i t (Go l l e r , Ger m an y ) u s es a si n g l e s tag e p r o ces s i n w h ich h ig h

d eg r ee o f h u m id i ty i s g en e r a t ed o n co t t o n f ab r ic s l ead in g t o e f f ic i en t s w e l l i n g o f

f a ts , w ax e s an d co t to n s eed s , p r o d u c in g g o o d w h i t en es s w i th l o w f ib r e d am ag e .

T h e C . R . C . p r o ces s (Cau s t i f i ca ti o n R ed u c t r i ce a ch au d i .e . c au s t i c iz in g , Re d u c -

t iv e , h o t ) f ro m S a n d o z i s a s im p l e a n d e c o n o m i c a l m e t h o d o f p r e - t re a t m e n t b y

w h ich co t t o n i s d es i zed , s co u r ed , b l each ed an d cau s t i c i zed i n o n e o p e r a t i o n . T h e

f lo w s h ee t d i ag r am s o f C . R . C . p r o ce s s eq u ip m en t a r e s h o w n in F ig . 1 1 -1 .

T h e co m b in ed d es i z in g , s co u r in g an d b l each in g i s m a in ly ach i ev ed b y t h e ad d i-

t i o n o f a s e c o n d p e r o x y c o m p o u n d t o h y d r o g e n p e r o x i d e o r s o d iu m c h l o ri te b a t h

w h en i ts r eac t i v i t y i s b o o s t ed s y n e r g i s t i ca l l y d u r in g b l each in g . In t h e ca s e o f H202,

t e t r a p o t a s s iu m p e r o x y d ip h o s p h a t e a s b o o s t e r a lo n g w i th s t ab i l i s e r an d n o n - io n i c

w e t t i n g a g en t i n th e b a th can ac t a s a s u b s t it u t e t o co n v en t io n a l p r o ces s w i th s av -

in g s i n w a te r an d en e r g y . T h e e f f ec t i v en es s o f t h e s y s t em u s ed u n d e r a lk a l i n e co n -

d i t i o n s can b e i n t e r p r e t ed i n te r m s o f f ree r ad i ca l f o r m a t io n .A n u m b er o f p a t en t s a r e av a il ab l e o n t h e u se o f em u l s i fi ed s o lv en ts i n co m b in ed



C o m b i n e d P r e - T r e a tm e n t P r o c e s s es o f T e x t i le s 3 41

Pad-roll r a n g e 4 ~ , , o ,.

(25-1 2 3 6

J-Box range (open w idth)

"V~ 9 9 ~ s

9 ~_,

1 2 3 s7

Pad-steam range4

- - - v : v . - . ~ v : : : : : - : :. v . : . - - - , : - ~ v . + . - - - . v . . v + + + .~ _ ~ . - . -~ v : . . _ .

1 2 :3 8 s

Figur e 11 -1 . C .R .C . ( S a ndoz ) p r oc e ss s e qu ipm e n t .

1 G r e y g o o d s f r o m t h e l o o m ( c o t to n o r p o l y e s t e r ) ;2 S i n g e i n g u n i t ; 3 I m p r e g n a t i o n b a th a t 2 0 -4 0 ~ ;

4 P a d d i n g m a n g l e ( 8 0 - 1 0 0 % p i c k - u p ) ;

5 W a s h i n g c o m p a r t m e n t s ( 95 , 9 5 , 7 0 , 5 0 , 3 0 ~ ;

6 Pad - ro l l ch am be r (60-120 ra in a t 90-95~ ;

7 J -B ox (20-60 ra in a t 95-100~ ;

8 S te a m e r ( 5 - 20 m in a t 10 0 - 107 ~

de s iz ing , s c our ing a n d b le a c h ing . I n one p r oc e ss , the c lo th is pa d de d w i th a n e m ul -

s io n c o m p r i s i n g o f a q u e o u s s o l u t i o n o f a lk a l in e c o m p o u n d e m u l s i fi e d i n c h l o ri -na te d hydr o c a r bo n wi th se l e c te d e m uls i f i e r a t 25 - 6 0~ d r i e d a nd s t e a m e d to r e -

m ove c h lo r ina te d hyd r oc a r bon s . I n a no the r p roc e ss , t he singe d a nd de s i z e d c o t ton

f a b ri c i s pa dde d w i th e thy le ne c a r bona te , pe r a c e t i c a c id a nd e m uls i f i e r i n tr i c h lo r o -

e thylene fo l low ed by hea t ing a t 95~ for 10 ra in . Solven t a ss is ted com bined des iz ing ,

s c o u r in g a n d b l e a c h i n g p r o c e s s u s i n g a m i x t u r e o f 4 % s c o u r in g a g e n t [ a m i x t u r e o f

p ine o i l (50 pa r t s ), non - ion ic e m uls i f i e r ( 40 pa r t s) , pe r c h lo r oe thy le n e ( 10 pa rt s )] ,

H20 2 ( 10 0 %) 1%, sod ium s i li c a te 2% a nd a c t iva to r 2% i s r e po r t e d [20] . The f a b -r i c s a r e pa d de d wi th the m ix tu r e a nd b a tc he d f o r 12 to 24 h a t 40 to 6 0~



3 4 2 C o m b i n e d P r e - T r e a t m e n t P r o c e s s e s o f T e x t il e s

S i n g l e s t a g e p r e p e r a t o r y p r o c e s s s f o r c o t t o n u s i n g s o d i u m h y p o c h l o r i t e i s

op t i m i s e d [ 21 , 22 ] . A p roc e s s ba s e d on e m ul s i f ie d s o l ve n t s ys te m a s s c our i ng a ge n ta l ong w i t h s od i um hypoc h l o r i t e a s a b l e a c h i ng c um de s i z i ng a ge n t a t pH 11 i s

r e po r t e d [ 23 , 24 ] . A round 30 -35% mo re hypo c h l o r i t e i s r e qu i r e d i n t he s i ng le s t a ge

p r o c e s s c o m p a r e d t o c o n v e n t io n a l b l e a c h i n g .

A f a s t de s i z i ng , s c our i ng a nd b l e a c h i ng s ys t e m us i ng s od i um c h l o r i t e f o r c o t -

ton -bas ed t ex t i l e m ate r ia l i s repo r ted [25] . In th i s proce ss , the fabr ics a re pad ded in

a s o l u t i on c on t a i n i ng 20 g / 1N a C 10 2 , 0 .0 5 g / 1K M nO 4 a nd 2 g /1 w e t t i ng a ge n t a t pH

10 t o a w e t p i c k -up o f a bou t 8 0 % . The t r e a t e d f a b r i c s a re the n e xp os e d t o 9 0~ fo r

3 0 - 6 0 m i n a n d w a s h e d a n d d r i ed .

A n o t h e r a p p r o a c h is t h e c o m b i n a t i o n o f a n en z y m e t r e a tm e n t w i th h y d r o g e n

p e r o x i d e [ 2 6 ] . B y c o m b i n i n g e n z y m e t r e a t m e n t ( a s i m u l t a n e o u s t r e a t m e n t o f

pe c t i na s e a nd c e l l u l a s e ), o r a l ka li ne bo i l -o f f, w i t h a n a l ka l ine pe rox i de b l e a c h i ng ,

t he to t a l de g re e o f w h i t e ne s s i s r e po r t e d t o be h i ghe r i n c om bi na t i on w i t h e nz y m e

t r e a t me n t . The c ombi ne d p roc e s s , i nc l ud i ng a n e nz yme t r e a t me n t , de l i ve r r e s u l t s

c ompa ra b l e w i t h t hos e o f a l ka l i t r e a t me n t [ 27 ] .

A s i ng l e s t a ge p r e pa ra t o ry p roc e s s on po l ye s t e r / c o t t on b l e nde d f a b r i c s c a n bec a r r i e d ou t u s i ng pe ra c e t i c a c i d a s a n ox i d i s i ng a ge n t . The f a b r i c i s t r e a te d w i t h a

s o l u t i on c on t a i n i ng pe ra c e t i c a c i d 5 -6 g /l , t e t r a s od i um pyro pho s pha t e 1 g /l , ba c t e -

r i al t ype d e s i z i ng a ge n t 1 g / l, c om m on s a lt 2 g/1 a nd non- i on i c w e t t i ng a ge n t a t pH

5 to 6 (m : 1 :: 1 : 3 to 1 : 5) a t 75-80~ for 90 min. T he t reate d fa bric is then w ash ed

w i t h ho t w a t e r a nd f i na l l y w i t h c o l d w a t e r .

S o l a r w a t e r he a t i ng s y s t e m fo r s ing l e s t a ge p r e pa ra t i on i n a k i e r a nd pa d -ba t c h

s ys t e m s w i t h a p roc e s s c os t s a vg i ng i s pos s i b l e [ 28, 29 ]. S o l a r he a t ma y be u t i l is e d

t o t he ma x i mum e x t e n t f o r d ry i ng t he f a b r i c t o r e duc e c ons umpt i on o f fue l .

R E F E R E N C E S

1 C . D u c kw or t h a nd L . M. W re nna l l , J . S oc . D ye r s C o l ou r i s ts , 9 3 ( 19 7 7 ) 407 .

2 S ou t he rn S e c t i on o f A A TC C , T e x t i l e C he m . C o l o r . , 14 ( 1 ) ( 19 8 2) 23 .3 B .C . B urd e t t and H. G. Ro ber t s , J . Soc . Dy ers Colour i s t s , 101 (2) (1985) 53 .



Com bined Pre -Trea tmen t P roces ses o f Tex t i le s 343

4 B. C . Bu rdet t and H. G. Rober t s , Low E nergy Preparat ion Process of Text i les ,

F i n a l R e p . N o . E U R / O O / B E N . P u b l is h e d b y t he C o m m i s s i o n o f E u r o p e a nCommuni t i e s , Luxemberg , 1985 .

5 K. Dickson, W . S . Hickm an, J . Soc. Dye rs Colour i s t s , 101 (1985) 283.

6 T. K. Das , A. K. Mandavawal la and S . K. Dat ta , Text i le Dyer and Pr in ter

(1986) 21.

7 H. E. Bi l le, J . Soc. Dyers Colouris ts , 103 (1987) 427.

8 K. Dickson, Rev. Prog. Col . Rel . Topics 17 (1987) 1.

9 G. Ro sch, Text i l Prax . In t. (M arch 1988) 264.

10 T. S. Sha rm a, R. M. Mit tal et al ., Co loura ge, 37 (20) (1990) 48.

11 An on. , Int . Dy er, 179 (1) (1994) 22.

12 M.L. Gul ra jani and N. Su kum er , J. Soc. Dy ers Colour i s t s , 100 (1984) 21 .

13 M.L. Gu l ra jani and N. Sukum er , J. Soc. Dy ers Colour i s t s , 101 (1985) 383.

14 I .C.I . , BP 1, 130 554 (1965).

15 Ka l inwasky , 1s t Shi r ley In t. Sem inar on so lvent base d proc ess ing of tex t i les ,

Manches ter (Oct 1969) .

16 T. S. Sh arm a et al ., Te xt i le Res. J ., (1989) 748.17 R. M. Mi t ta l , M. L . Gul ra jani and R. Venk at ra j , Ame r . Dye s tu ff Rep. , No. 4

(1988) 20.

18 An on . , Int . Dy er, 177 (1992) 2.

19 Anon. , Dyer, (Apr 1995) 22.

20 N. S uku m ar and M. L . Gul ra jani , Ind . J . Text i le Res . , (1986) 38.

21 J . M il i tk 'y, Tex t i le Res. J ., 58 (1988) 672.

22 J . C. W hitw ell , Tex t i le Res. J ., 57 (1987) 239.

23 M .L . Gul ra jani and N. Sukum ar , J. Soc. Dye rs Colour i s t s , 100 (1984) 21 .

24 M. L . Gul ra jani a nd N. Su kum ar , Text i le Res . J ., 55 (1985) 367.

25 M. H. E1-Raf ie e t a l ., Am er , D ye s tuf f Rep. , 79 (Dec 1990) 43 .

26 E. Ba ch and E. Schol lma yer , Text i l Praxis , 3 (1993) 220.

27 U. Ro ssner , Me l l iand Text i lber . , 2 (1993) 144.

28 M . L. Gu lrajani , S . Gu pta and S. K. Gupta, Tex t i le Res. J. , 59 (4) (Ap r 1989)

217.

29 M. L. Gu lrajani an d S. Gup ta, J. Soc. Dy ers Colo uris ts , 106 (1990) 98.



Chapter 12

D E G R A D A T I O N O F F I B R E S A S S O C I A T E D W I T H C H E M I C A L

P R E - T R E A T M E N T P R O C E S S E S

1 2 . 1 I n t r o d u c t i o n

F au l t l e s s p r e - t r ea tm en t s o f tex t i l e s a r e v e r y e s s en t i a l f o r t h e q u a l i t y o f t h e f i n al

p r o d u c t s . F au l ty p r e - t r ea tm en t s im p a i r t h e r ep r o d u c ib i l i t y o f t h e d es i r ed e ff ec t

w i th an i n c r ea s ed am o u n t o f r e j ec ts . G en e r a l l y , t h e d e f ec ts can b e c l a s s i f ied i n to

tw o b r o ad c l a s s e s n am e ly , g r ey m i l l d e f ec t s an d d e f ec t s d u r in g ch em ica l p r o ces s -

in g . T h e g r ey m i l l d e f ec ts a r e a r i s en f ro m y a r n d e f ec ts , w a r p - w i s e w ea v in g d e -

f ec t s , w e f t - w i s e d e f ec t s an d g en e r a l d e f ec t s . T h e d e f ec t s i n ch em ica l p r o ces s in g

m ay b e c l a s s i f ied a s ch em ica l d am ag e , m ech an ica l d am ag e o r o p e r a t i o n f au lt s .

C h e m i c a l d a m a g e s a r e c a u se d b y t h e i m p r o p e r a p p l i c a ti o n o f p r e - t re a t m e n t p r o -

ces s es , e r r o n eo u s c o n cep t o f p r o ced u r e , f a u l ~ o p e r a t i o n o f m a ch in es , f au l t y feed -

in g o f ch em ica l s an d h ap h aza r d w o r k . E x ces s iv e t en s io n o r s tr e t ch m ay o f t en b e

t h e c a u se o f m e c h a n i c a l d a m a g e .

De g r ad a t i o n o r d am ag e d ep en d s o n ch em ica l s t ru c tu r e o f i n d iv id u a l f ib r e an d

p r e - t r ea tm en t h i s to r y . Deg r ad a t i o n a l s o i n v o lv es ch an g es i n m o lecu l a r s t r u c tu re o f

th e f i b re . F u r th e r , t h e s t r en g th o f co t t o n y a r n s d ep en d s n o t o n ly o n t h e s t r en g th o fthe f ib res , bu t a l so on the twis t and the lubr ica t ion o f the f ib res . S imi lar ly , h igh and

low c r imp w ool f ib res, as a r esu l t o f the in f luence o f nu t r i t ion leve ls , have d i f f e ren t

l ev e l s o f d eg r ad a t i o n d u r in g ch e m ica l p r o ce s s in g [ 1 . M o lecu l a r o r i en t a t io n i n a

s y n th e t i c f i b r e , f ab r ic t h i ck n es s an d s p a c in g i n a w e av e can a l s o m o d i f y t h e w ay in

w h ich f ab r i c i s d eg r ad ed b y ab r a s io n . Deg r ad a t i o n m ay a l s o a r i s e a s a r e s u l t o f

s to rage , main tanance p rocedure , exposure to u l t r a -v io le t sources , weather ing , fung i

o r o th e r m ic r o b io lo g i ca l a t tack , h ea t an d ac id an d a lk a l i n e h y d r o ly s i s o f fi b re s .

1 2 . 2 D e g r a d a t i o n o f C o t t o n D u r i n g D e s i z i n g

Des iz in g i s ca r r i ed o u t t o r em o v e t h e s i ze s an d i t s d eg r ad a t i o n p r o d u c t i s r e -

m o v ed f r o m th e f ab r i c b e f o r e s u b s eq u en t p r o ces s in g . In r o t - s t eep in g , t h e c lo th i s

a l l o w ed to li e f o r ab o u t 2 4 h an d t h e f e r m e n ta t i o n i s n o t co n t r o ll ed . T h e d eg r ad a -

t ion o f ce l lu lose m ay oc cur as a r esu l t o f c ross in fec t ions e .g . o f m i ldew. The loss in

w e ig h t i n ac id s t eep in g i s s li g h t l y h ig h e r th an w i th w a te r s teep in g . Co t to n f ab r ic s

t r ea t ed w i th d i lu t e s u lp h u r i c ac id a t r o o m t em p er a tu r e s h o w l i tt le d eg r ad a t i o n , t h e



Deg radation of Fibres Associated with Chem ical Pre-Treatm ent Processes 345

fluidity increases from 4 to 5.8 rhes in 4 h and abou t 70% o f the s tarch is remo ved.

Gen erally dilute solutions o f mine ral acids and acid prod ucing salts such as ZnC12and A12C16 hav e little action on co tton fibre p rovid ed they a re wa shed out befo re

the f ibre is dried [2-4]. I f wa shing is not done, hydrocellulose, a break d ow n prod-

uct of cellulose, is produ ced with conseq uent tend ering o f the f ibre [Fig. 12-1].

H CH2OH \ H OH [H CH2OH

o - ~ H ~ O ~ H O I-~ i~ H H ~ HI ~ ~ ' O ~ H ~ H O -

ILI O'H ] H 7H 2 O H O

l i

,,[, +2H20

H C H2 OH \ H OH [ C H2 O H

o ~ H H o H H - - ~ I O ? 2 H + H{0t ~ Q ~ O

2 \ H OH n

Figure 12-1. Me chan ism of hydrolysis of cellulose molecule.

Due to partial hydrolysis o f the cellulose m olecule, the average m olecular leng th is

reduced. The appearance of addit ional -C HO H end groups increase the reducing

pow er because they can undergo tautomer ic change in the format ion of a ldehyde

H O H H i O H I

- O H ~ H H ~ c / H - 0 ~ ~ C - - ~ ' - . ~ / H-. " . .~OH H U \

O / \ O H n C -O H \ O HCH2OH t

CH2OH

Figure 12-2. Form ation o f aldehyde g roup on hydrolysis .

[Fig. 12-2] . M ost orga nic acids in dilute solution have little effect on cotton even if

dried in, bu t oxalic, citric and tartaric acids are liable to cause ten derin g [5].

W hen sodium b rom ite is used as a desizing agent for cotton fabric by continu-

ous and discontinuous processes, the concentrat ion o fbro m ite should be restr icted

to ensure that the ox idaiton o f cellulose is kept to a negligible propo rtion.

In enzym atic desizing, the t ime, tem perature and pH of the desizing bath is well

controlled. Furthe rmo re, the action of enzym e is restricted only on the sizes presen t

on the fabric and thus degradation of the f ibre due to enzymatic desizing is few and



346 De g r a da t ion o f F ib r e s Assoc ia t e d wi th C he m ic a l P r e - Tr e a tm e n t P r oc e sse s

fa r be tween. R epea ted t rea tment ofce l lu lase e nzym es f rom Penic i l l ium funiculosum

[6 ] a nd t r i c hode r m a e ndoc e l lu l a se e nz ym e s [7 ] l e a ds to e x te ns ive f r a gm e n t ion o fc o t ton f ib r e s . R e pe a te d e nz ym e t r e a t e d c o t ton shows C e l lu lose I pa t t e r n w i th the

abse nce of 101 p lane s imi la r to tha t of dras t ica l ly ac id hydro lysed cot ton [8] . This

c onf i r m s tha t e nz ym a t i c hydr o lys i s o f c o t ton f ib re s p r oc e e ds p r e f e r e n t i a l ly a long

the o r i e n ta tion , w h ic h i s a c l e a va ge pha se . M o r pho log ic a l c ha n ge s t a ke p l a c e du r -

ing the phases of degrada tion . Ac id hyd rolys is causes loca l ised degrada t ion w hereas

e nz y m a t i c hy dr o lys i s i s un i f o r m . Th e r e a r e c ha nge s in m o i s tu r e r e ga in , c r ys t a l li n -

i ty o f t he hydr o lysa te s a nd w e igh t lo s s due to e nz ym e h ydr o lys i s .

12 .3 D e gr ad a t i on o f Co t ton D u r i n g S cou r in g

S c ou r ing o f c o t ton i s ge ne r a l ly c a r r i e d ou t unde r m i ld c on c e n t r a t ion o f a lka l i.

Th e sco ur ing t rea tm ent inc reases the we t tabi l i ty o f the f ibre , but i t induc es f ibre

de gr a d a t ion unde r s e ve r e c ond i t ions b y c r e a t ing c r e v ic e s in fib re o r d i s so lu t ion o f

cut ic le or pr im ary w a l l [9 , 10 ] . Th e ma in chang es in co t ton dur ing scou r ing process

a re loss in we ight ( about 5-10%) , loss in length due to shr inkage and a l te ra t ion in

coun t a f fec ted by bo th losses and chang es in tens ile s t rength (genera l ly an inc rease )

[ 11 , 12]. S ince the s cour ing t rea tm ent co nt r ibutes to the d isso lu t ion of a por t ion ofshor t e r c e l lu los i c c ha ins , i t be s tows on c o t ton a n a ve r a ge DP h ighe r tha n tha t o f

na t ive c e l lu lose . Th e a lka l i t r e a tm e n t o f s c our ing c ond i t ion doe s no t i nduc e p r o -

no un ced chan ges in the f ine s t ruc ture of f ibres and has a smal l e f fec t on the degree

of c rys ta l l in i ty [ 13 ] .

The de g r a da t ion o f c e l lu lose in a lkal i so lu t ion de pe n ds on the c onc e n t r a t ion o f

a lka l i a nd on the p r e se nc e o r a bse nc e o f oxyge n . I n the a bse nc e o f a i r c e l lu lose i s

s lowly a t t a c ke d by ho t a lka li i n a s te pwise f a sh ion a t t he r e duc ing e nd o f the c e l lu -

lose cha in [ 14] resul t ing in a loss of m ate r ia l . The ent rappe d a i r should b e sw eeped

ou t be f o r e k i e r bo i l ing unde r p r e s su r e . T he c o t ton m us t be e n t i r e ly c o ve r e d by the

scou r ing l iq uor as o the rw ise pa r t of the f ibre expos ed to the a ir loose s t rength and

resul t in uneve nne ss in dye ing . F ig . 12-3 show s the ro le of pH in the endw ise

de p o lym e r i sa t ion o f hydr oc e l lu lose f r om c o t ton by t r e a tm e n t in Na OH so lu t ion

(0.5 to 18 .6 N) a t 120~ Th e curve show s a pa t te rn s im i la r to the degree o f swe l l -

ing o f c e l lu lose in alka li . The num be r o f c a rboxy l g r oups inc r e a se s w i th inc r e a s ing

[OH] ion concent ra t ion , wi th a rap id ra te be tween 6 and 8 .5 N, but the v iscos i tyde c r e a se s on ly s l igh t ly , wh ic h im p l i e s the lo s s o f l ow m ole c u la r we igh t c om po-



D e g r a d a t i o n o f F i b re s A s s oc ia t e d w i th C he m ic a l P r e -T r e a tm e nt P r oc e s s e s 347

0 . 5

r

e~o 0.4r

0.1

o 0 . 3

o 0.2o

o0 . 1

r

" \ \

5 1 0 1 5 2 0

[OH- ] ( m ole / l )

Figu re 12-3 . Ef fec ts of a lka l i conc ent ra t ions on the extent

o f h y d r o c e l l u l o s e d e g r a d a t i o n at 120~ for 1 h [15].

nents . The los s in we igh t , how ever , increases w i th temperature o f the a lka l ine so lu-

t i on [ 16 ] . T he r e ac t i on s c he m e o f th i s k ind o f de gr ada t i on i s r e pr e s e n te d in

F ig . 12 - 4 b y the for m at ion o f pe e l ing - o f f c e n tr e s on the c e l lu lo s e i .e . a lde hyde

r

r-t~ ....... 0 - - J \ , C. , / I. . . . . . . C . . 2~ u

/ /

: 3 O HI

C~ 20

R ~ - - - o - k c / c Z !~ ( ~ / ' ~ w ! H

C OH

9~ ! 2 0

C H ~OH

H C . . . . . . . O,

r~ . . . . O . - - J }c - . . . . . C,,./

..-3 J" OH

% ~~7.

Figure 12 -4 . [3 -a lkoxy e l imin at ion rea c t ion [21 ] .



3 4 8 D e g r a d a t i o n o f F i b r e s A s s o c i a te d w i t h C h e m i c a l P r e - T r e a t m e n t P r o c e s s e s

g r oups , by p - a lko xy e l im ina t ion r e a c t ion f r om the r e duc ing e nds o f the c ha ins , by

t h e f o r m a t i o n o f c a r b o n y l g r o u p s c o n t a i n in g c o l o u r ed p r o d u c t s a n d y e l l o w i n g [ 1 7]a nd by the f o r m a t ion o f m e ta sa c c h a r in i c a c id a t t he e nd o f the c ha ins [ 18 -20 ] .

I n the p r e se nc e o f a i r i .e . t he r e a c t ion o f oxyg e n w i th c e l lu lose in p r e se nc e o f

s t r ong a lka l i ( a bove 40 g / l ), t he de g r a da t ion c a n be ve r y se r ious a nd the ox ida t ive

a t t a c k m a y l ike ly to f o l low the pa t t e r n sugg e s te d f o r a lka l i c e l lu lose [22] . The a t-

t a c k o f ox yge n a t 20 ~ i s s low, r a p id a t 40 - 50 ~ a nd is 10 0 0 t im e s h ighe r a t 9 5~

tha n a t 20 ~ [22 ] . A the o r y ba se d on f re e r a d ic a l in t e r m e d ia t e s i. e. t he ox ida t ive

de gr a d a t ion w h ic h o c c u r s w i th c ha in sc i s s ion i s shown in F ig . 12 -5 . It is show n tha t

INITIATION SIEP

OH (~H O i H ? Hi

....... C - C ~ 0 2 .. .. .. .. .. . r ..... C ~ i,, ..~~ C)O

t I I "

H H HI f,1

,P.Rg~AszA3~ Sl F.P

O H O H " ~ ?H o H oHI i $

- - C - - C . . . . 0 2 - - ~ " - - C - - C . . . . . . ~ - - C - - C - - 9 l If " I I I

~.. H ~) H 0; - &

~ : ] I f I 2 "

qH 9 ~ qH ~- - C - - C - - - - - ~ - - C - - C - - 9 H O "

t t I ,~H 0 H 9 "

OH

OHH~ tOH 0H. ~ : . ~ H , OH~ OH. .OHi

.... ,: ......c . . . . . . . . . c - c . . . . . . . . . . . . . . c - - . c . . . . . . c -9 9 I t

e

0 H H

( } f . i 3 ~

....... C ... ~... -- - H O '- .. . .. .:. I

H H.,:

:3 " . O.O " . .......~-

.,.3 ta O H

( . . - - C . . . . ~ ~ 2 0f '

~4

Ii.

H 2 0 2

F O i . ~ M A T ~ O N O F C A R B O N Y L G R O U P S

q H 9 H ,q ,H

..... c ..... c - - - ' - I - f - "

u ~ . 2 L

Figur e 12 -5 . F r e e r a d ic a l m e c ha n i sm o f a lka l i c e llu lose a u to - ox ida t ion [22] .



D e g r a d a t i o n o f F i b r e s A s s o c i a t e d w i t h C h e m i c a l P r e - T r e a t m e n t P r o c e s s e s 3 4 9

h y d r o g e n p e r o x i d e is a l w a y s p r e s e n t d u ri n g c e ll u lo s e a u t o - o x id a t io n . O x y g e n m a y

a t t a c k o n h y d r o g e n a t o m a t C 2 o r C 3pos i t ion to p rod uce a r ad ica l I I in the ce l lu lose .Rad ica l I I m ay th en r ap id ly t ak e u p o x y g en f o r m in g a p e r o x id e t y p e r ad i ca l I I I

w h i c h m a y r e a c t w i t h o t h e r g r o u p s i n c e l lu l o s e t o g i v e h y d r o p e r o x i d e I V a n d t h e

o r ig in a l r ad i ca l I I. T h u s , a ch a in r eac t i o n m ay b e s e t u p . Hy d r o p e r o x id e IV g iv es a

h y d r o x y l r a d i c a l a n d a n e w r a d ic a l V , w h i c h m a y a b s tr a c t h y d r o g e n f r o m c e l l u lo s e

to g iv e co m p o u n d VI an d t h e o r ig in a l r ad i ca l I I . T h e h y d r o x y l r ad i ca l m ay a t t ack

ce l l u lo s e t o g iv e n ew ty p e I I r ad i ca l s ( i n au to ca t a ly s is ) . Hy d r o x y l r ad i ca l s m ay a l s o

c o m b i n e t o f o r m h y d r o g e n p e r o x i d e . C o m p o u n d V I f i n a l l y l o s e s w a t e r w i t h t h e

f o r m a t io n o f ca r b o n y l g r o u p in t h e ce l lu lo s e ch a in co m p o u n d (VI I ) an d t h u s ch a in

s c i s s io n m ay o ccu r b y [3- alko x y e lim in a t i o n . T h e r a t e o f r eac t i o n o f a lk a l i c e l l u lo s e

w i t h o x y g e n i n c r e a se s w i th t h e n u m b e r o f r e d u c i n g e n d g r o u p s .

An io n i c m ech an i s m (F ig . 1 2 -6 ) i s a l s o p r o p o s ed f o r t h e au to - o x id a t i o n o f a l -

.CA...N._N.[Z.ZA,RO RE A C T IO N

0 0 -/ / I

C e l l - C 9 O H - ~ - -" '" C e l l - C - H\H I

OH

g ' ~ l X

!

C e i l - C - H 9O H - ~ C e l l - C - H 9 H 2 0, I

OH O -

F O R M A T I O N OF P E R H Y D R O X Y L I O N

0- o

C e l l -C - H 9 2 .....~ C e I I - C 9 H O O\

O H O H

I x xE

soC e i l - C - . - H . 0 2 - - " * C e l t - C .- H O 0

I ",O - O -

X X!I

F ig u r e 1 2 -6 . Io n i c m ec h an i s m o f a lk a l i c e l l u lo s e au to - o x id a t i o n [2 3 ].

k a l i c e l lu lo s e [ 2 3] . T h e r ed u c in g a ld eh y d e g r o u p s i n ce l lu lo s e u n d e r s t r o n g a lk a li n e

c o n d i t i o n f o r m C a n n i z z a r o i n t e r m e d i a t e s s u c h a s I X a n d X w h i c h i s a u t o -

o x id i s ab l e . T h e i n i t ia t i o n s t ep o f au to - o x id a t i o n r eac t i o n co n s i s t s o f t h e f o r m a t io n




o f the pe r hydr oxy l ion . The p r opa ga t ion s t e p i s t he a t t a c k o f c e l lu lose by the

perh yd rox yl ion wi th rupture of the ce l lu lose cha in and i s s imi la r to the degrada t ion

m e c h a n i s m d u r i n g b l e a c h in g w i t h h y d r o g e n p e r o x i d e.

12 .4 Degradat ion o f Cot ton During B leach ing

B le a c h ing a ge n t s c om m only use d a r e m a in ly ox id i s ing a ge n ts wh ic h r e a c t w i th

c e l lu lose f o r m ing oxy c e l lu lose w i th a c c om pa ny ing t e nde r ing o f the fa b r ic . The

r a t e o f de c om pos i t ion o f b l e a c h ing a ge n t a nd a l so the r at e o f a tt a c k on c o t ton de -

pe nds on c onc e n t r a t ion , pH , t im e a nd t e m pe r a tu r e o f the b l e a c h ing ba th a nd a lso

on the so i l s present in the fabr ic . Ov er b leachin g takes p lace due to lack of prop er

cont ro l of these pa ra m ete rs and oxida t ion proc eeds a t a fas te r ra te and fabr ic i s

de s t r oye d . Te n de r ing t a ke s p l a c e i f b l e a c h ing i s c a r r ie d ou t i n p r e se nc e o f m e ta l s

wh ic h a c t as c a t a lys ts i n a c c e le r a t ing the ox ida t ion p r oc e ss . Te n de r ing a l so t a ke s

p la c e i f t he r e m ova l o f b l e a c h ing a ge n t du r ing wa sh ing t r e a tm e n t i s i nc om ple te .

Gen era l ly , b leac hed c lo th i s soured wi th HC1 (1 .5%) or H2SO 4 (1 .0%) to rem ov e

c a lc ium c a r bona te o r m e ta l l i c c om p os i t ion de pos i t e d in the clo th . Te nd e r ing due to

a c id m a y a l so oc c u r i f t he a c id i s no t p r ope r ly wa sh e d- o f f a f te r the goods a r e

sour e d . Hyd r oc e l lu lose m a y f o r m due to a c id a c t ion on c el lu lose on s to ra ge .Ye l low ing o f the b l e a c he d f a b ri c i s a no the r de f e c t. Ye l low ing o f the c o t ton f a b -

r i c is c a use d by im pr ope r c on t r o l o f b l e a c h ing c ond i t ion pa r a m e te r s , f a u l ty wor k -

ing o f the k i e r du r ing b o i l - o f f ope r a t ion , poor c i r c u la t ion o r f i l t er ing o f som e c o t -

ton im p ur i t i e s a nd de f e c t ive c i r c u la t ion o f b l e a c h l iquor . The ye l low e r the sub -

s t ra te , the h ighe r i s the oxyc e l lu lose presen t and the m ore s uscept ib le the fabr ic to

a f t e r - ye l lowing on s to r a ge .

12 .4 .1 Sod ium hypoeh lor i t e b l each ing and dam age

B le a c h ing o f c o t ton wi th sod ium hypoc h lo r i t e so lu t ion i s done in a lka l ine c on-

d i t ion ( pH 8 .5 to 10 ) by the the a dd i t ion o f sod ium c a r bona te . M a x im um da m a ge

to the fabr ic takes p lace in the neut ra l r eg ion o fp H (Fig . 12-7) . Aro und pH 7 .0 , the

hypo c h lo r ous a c id a nd hypoc h lo r i t e ion a r e p r e se n t a t a pp r ox im a te ly the sa m e c on-

cent ra t ions and hence the ra te of a t tack on ce l lu lose i s grea tes t in th is reg ion . The

de gr e e o f de g r a da t ion i s de m ons t r a t e d by inc r e a se in f lu id i ty wh ic h a l so show s a

m a x im um a t a pp r ox im a te ly pH 7 .0 . The t e m p e r a tu r e o f the l i quor shou ld be ke p t

a s low a s poss ib l e a nd a l so d i r e c t sun l igh t shou ld be a vo ide d to e nsu r e m in im umoxyc e l lu lose f o r m a t ion . B le a c h ing w i th sod ium hypo c h lo r i t e c a n be done a t 20 ~



D e g r a d a t i o n o f F i b r e s A s s o c i a t e d w i t h C h e m i c a l P r e - T r e a t m e n t P r o c e s s e s 3 51

2 .4

0

/ 6 !. , , . . . ,~

. , , . . , . .~

E= / 2

o

E

c,.) ~5

,.:?-S 3 4 S

/

. . . . , , , , , , , . , . , . / /i - - , \

9, j , , "

N , ~ , j , "

6 " 7 8 9 / 0

p H

Figur e 12 -7 . De g r a da t ion o f c o t ton wi th se l f -bu f f e r e d hypo c h lo r i t e

sol utio n (3 g/1 av. C12) af ter 5 h treat m en t [24].

f o r a t r e a tm e n t t im e o f 16 h , bu t t he sa m e r e su l t c a n be o b ta ine d f o r 30 m in a t 60 ~

wi thou t a pp r e c ia b le inc r e a se in da m a ge to c e l lu lose [25 , 26 ] . The de g r a da t ion o f

c o t ton a t e l e va te d t e m p e r a tu r e p r oc e e ds f a s t e r t ha n tha t o f im pur i t i es , bu t t he e f f e c t

i s d e p e n d e n t o n l y o n t h e e f f e c ti v e h y p o c h l o r i t e c o n s u m p t i o n . C e r t a i n m e t a l s s u c h

a s m e r c u r y , c oppe r , c oba l t , n i c ke l a nd i r on shou ld be a bse n t i n the b l e a c h ba th a s

the ox ide s a nd hy dr ox ide s o f the se m e ta l s a r e ab le to c a ta lyse the de c om pos i t ion o f

h y p o c h l o r i t e s o l u t i o n a n d t h e l i b e r a t e d o x y g e n c o n v e r t s t h e c e l l u l o s e i n t o

oxyc e l lu lose . C e r t a in ye l low a n d o r a nge va t dye s a l so a c c e le ra t e the ra t e o f ox ida -

t io n a c c o m p a n i e d b y d e g r a d a t i o n o f c e l lu l o s e u n d e r c o m b i n e d a c t io n o f h y p o c h l o -

r i te so lu t ions and l ight [27 ] .

The r e a c t ion o f h yp oc h lo r i t e w i th c e l lu lose i s non - spe c i f i c i .e . no t c on f ine d to a

p a r t i c u l a r h y d r o x y l g r o u p . T h e d e g r a d a t i o n i s lo c a t e d m a i n l y o n t h e s u r f a ce o f t h e

f ib re a s the r e a c t ion i s he t e r o ge n e ous na tu r e . Hyp oc h lo r i t e m a y a t t a c k a nd c on ve r t

the a c c e s s ib l e hyd r oxy l g r oups o f c e l lu lose in to c a r bony l g r ou ps ( i. e. a lde hy de a ndke tone g r oups ) a nd c a r boxy l g r oups w i th subse q ue n t c ha in c le a va ge . S t r e ng th lo s s ,



352 Degrad at ion o f F ibres Assoc ia ted w ith Chem ica l Pre-Treatment Processes

in the ear ly s tages , i s accompanied with s l ight weight lo ss but s t ength decreases

rap id ly with cont inued o x idat ion [28] . The form at ion and ex tent o f carboxy l con -

tent s (determined b y me thy lene b lue absorpt ion) and a ldehyde groups (determined

by Copper No . ) depend on the pH o f hypochlor i t e so lut ion during the t rea tment

(Fig . 12-8 ). U nder ac id ic pH reduc ing type (a ldehyde and keto groups) and under

~-~.

, '~ . )

9 ( " f " - . , \ ,! ':

. / ,- !:~I

9 , w ~ . , , ~ . ~- ) ....

,; . r...~......, , ~i i ~ ~ ..... I N v . , .

..... ~ , - ~ w . . : ~ : r ~ : ; ' - - -

:. 2 3 ~, !'.:., ~.~ 7 ~~ ~...~ :.,.:.', ~ ,;;.. '..3 .4

Figure 1 2 -8 . E f fec t o fp H o fh y p o c h lo r i t e s o lut ion s o n th e c o p p ern umb er a n d m et h y len e b lue a bso rp tio n o f o x y c e l lu lo s e [29].

a lka l ine pH ac id ic type ( carboxy l groups) o f oxyce l lu loses are formed. The ch anges

in pH m od ify the ra tes o f reac t ions but do no t a lt er the m echan ism for them [30].

The ox idat ion m ay be progress ive and proceed s a long a course know n as [3 -e limi-

nat ion [Fig . 12-4 ] . Bleach ing with hypochlor i t e i s done in a lka l ine pH and hence

oxy ce l lu lose o f the ac id ic k ind are insensa t ive to a lkal i, but wh en in the free ac id

form, the hydrogen ions from the carboxyl groups cata lyse hyd rolys is o f the adjascent

g luco s id ic l inkage . A sequen ce o f reac t ions i s show n in Fig . 12-9 and 12-10 [30 ].

0 . f

I v

0 )

0 ..,.. H <....~

C / " :')H

H H C ,, 0 ................- ~ ~ , - C 9 i ) . . .. . . .. . . . . , C - 0 . ~ , ~

0 "~ " " ~5~, {OC; ,t~ - c - H H , ~ , 0

H O / ~ - .

/u

Figure 12-9 . Oxidat ion with periodate [30] .



D e g r a d a t i o n o f F i b re s A s s o c i a t e d w i t h C h e m i c a l P r e - T r e a tm e n t P r o c e s s e s 3 5 3

~,~"

9. i t + . 9 f..7 C O H t iOCH i "

-y - .. ",-:z ... ""

, , ~ / 0 ! # " ,3

e , , ( . ~

t

0 ,\ iv ~ o / !.~C " ' \ c i

C = 0 (~,oJ .,~(>~ ... ,,- , O<

o . . . - C L . ~ ~O r j C 0

C 8 ~~ i , ) 1 \

> , , , ,

, < , , , , , 4

F i g u r e 1 2 - 10 . G e n e r a l r e a c t i o n s w i t h n o n - s p e c i f i c o x i d i s i n g a g e n t s [ 3 1] .

A p a r t f r o m d e g r a d a t i o n o f fi b re , th e i n c r e a s e in th e n u m b e r o f a ld e h y d e a n d c a r-

b o x y l g r o u p s a l s o i n c r e a s e th e d y e i n g a n d f i n is h i n g p r o b l e m s .

12.4.2 Hydrogen peroxide bleaching and damage

B l e a c h i n g o f c o t t o n w i t h h y d r o g e n p e r o x i d e is c ar r ie d o u t u n d e r a l k a l i n e c o n d i -

t i o n a l o n g w i t h s o d i u m s i li c a te w h i c h a c ts a s a s ta b i li s er . H o w e v e r , t h e u s e o f s o -

d i u m s i li c a te i s li a b le t o c a u s e d e p o s i t io n o f s il ic o n c o m p o u n d s o n t h e c l o th a n d

a l s o f o r m h a r d c r y s t a l l i n e d e p o s i t s o n p l a n t s a n d m a c h i n e r i e s w h i c h m a y c a u s e

a b r a s i o n d a m a g e t o th e f a b r ic . T h i s d e f e c t m a y b e a v o i d e d i f a d d i t io n o f a lk a l i in

t he ra ti o o f N a 2 0 : S i O 2 w i t h i n t h e r e g i o n o f 2 .2 5 : 2 .75 i s u se d . I t i s a lso r e c o m -

m e n d e d to u s e a m i x t u r e o f e q u a l p r o p o r ti o n o f N a O H a n d N a 2 C O 3 i n s te a d o fN a O H a l o n e a s o n l y N a O H m a y c a u s e i n it ia l d e g ra d a t io n . T h e s i l ic a t e c o n c e n t r a -

t io n m a y b e r e d u c e d f u r t h e r b y t h e u s e o f o r g a n i c s t a b i li s e rs w h i c h t e n d t o h a v e

l u b r i c a t i n g e f f e c t.

T h e d a m a g e o f co t to n d u r i n g m e t a l c a t a ly s e d b l e a c h i n g w i t h h y d r o g e n p e r o x i d e

i s a s e r io u s p r o b l e m . T h e r e a r e v a r i o u s s o u r c e s b y w h i c h t h e b l e a c h i n g b a t h c a n b e

c o n t a m i n a t e d w i t h m e t a l p a r t ic l e s . T h e r a w c o t t o n c o n t a i n s h i g h m e t a l c o n t e n t b e -

c a u s e o f t h e u s e o f p e s t i c id e s , f u n g i c i d e s a n d w e e d c o n t r o l a g e n t s i n c o t t o n - g r o w -

i n g [ 3 2 , 3 3 ] . D u r i n g o p e n e n d sp i n n i n g , so i l p a r t i c l e s wh i c h a r e r i c h i n m e t a l c o n -

t a i n i n g c o m p o u n d s , a r e d e p o s i t e d i n t h e r o t o r c h a m b e r a n d a f t e r t e m p o r a r y r e -



3 5 4 Deg r ad a t io n o f F ib r e s Asso c ia ted wi th Ch em ica l P re - T r ea tm en t P r o cesse s

m ova l ge t in to the yarn [34]. By increas ing the sp inn ing and weaving speeds the

co n tam in a t io n o f m e ta l p a r t ic l e s m a y a l so in c r ea se d u e to f r ic t io n f r o m m ach in e r y

com pone nts [35]. Meta l ions p resen t in chem ica ls used fo r b leach ing can a lso cause

p r o b lem s [3 6 ] .

Th e in f lu en ce o f th e co n cen t r a t io n o f i ro n io n s o n d eco m p o s i t io n o f h y d r o g en

perox ide in b leach ing l iquor is show n in F ig . 12-11 . The in f luence o f the concen-

t ra t ion o f complex ing ag en t on decomp osi t ion o f i ron com plex ing perox ide b leach-

ing l iquor and c e l lu lose is show n in F ig . 12-12 . The rap id re lease o f la rge am ount

F e ( N O 0 ~

[g/ l]

1 0( ]. . ~ - " " " " ~ " " " ' ~ ' ~ . . . . . . . .. . . . . . . . . . . . .. . " ~ 1 .0

"" " --'-',' 0 !90 f r 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 0

8o ,i / . ............7

7 0 I i { ' , / " "

00l! / -- 60

:2::

3011 j ' . ,0 01

;~ li ' ~.,---'." ~ . ..-.-...4 -- 200 ' : - - . - " ' ' " . . . . . . . . . . . . . .9 . . .. . . " U .,). ...... ..9 .@ ..... ...~. "

! .r "a~ .,.--,""~"",,.~.,.....s. 0

00 5 10 20 30 40 50 60

Time (min)

Figure 12-11 . Decom posi t ion curve o f

H202 i n b l each in g l iq u o r a t v a r io u s

Fe(NO3) 3conce n t ra t ion [37] .

m) P

2 5 00

~_ _ ~ , . . .~ . .~ , , , . . . . ~ . . : . .. .. .~ :2000

r ~~ ~ 00

1000

500

,_. __+.._ _-+-: ._ . . . _ . . _ : . _ _ _._ _=_ .. .. .. :_ ...... . ... ..........= 0

5 10 15 20 25 30 35 4 0

Com plexing agent (g/l)

Figure 12-12 . Decom posi t ion o f H 2 0 2 andd am ag e to co t to n a s a f u n c t io n o f t h e

concen t ra t ion o f the com plex ing agen t ,

fa l ling curve H202 , r i s ing curve D P.

of oxy gen spec ies causes rap id and s ign i f ican t ox ida t ive degrada t ion o f co t ton

ce l lu lose in the imm edia te v ic in i ty o f the meta l l ic par t ic le . The de com posi t ion e f -fec t o f water so lub le ca ta lys ts on perox ide and ce l lu lose can be suppressed by

increas ing the com plex ing agen t concen t ra tion . The ca ta ly t ic dam age tha t occurs

dur ing perox ide b leach ing i s due to the meta l l ic par tic les t rapped in the fabr ic and

th e d eco m p o s i t io n ofHzO2 s thought to be ca ta lysed by m eta l ions p resen t ne ar the

sur faces o f the me ta l lic par t ic les [38] . The ca ta ly t ic damage caused by m eta l sa l t s is

m ost s t r ik ing in a long l iquor ba th and leas t wi th the pad-ba tch method .

1 2 .5 D a m a g e o f W o o l D u r i n g P r e - t r e a t m e n t P r o c e ss e s

Bo i l ing water can g radua l ly b reak dow n the wool kera t in and the f ib re can loose




i ts s t rength . Di lu te ac ids , however , have l i t t le e f fec t on wool , but 20% HC1 can

hydr o lyse woo l . C o ld c onc e n t r a t e d m ine r a l a c ids c a n d i s so lve woo l f ib r e [39 ] .D i lu t e so lu t ions o f c a us t i c a lka l i e s r a p id ly d i s in t e g r a t e woo l a t a r a t e de pe nd ing

upon the t e m pe r a tu r e a nd c onc e n t r a t ion e m ploye d . S oda - a sh a nd sod ium c a r bon-

a te hav e m uc h less des t ruc t ive e f fec t and hence a re used in scour ing o f wo ol f ibres .

B or a x , soa p a nd a m m onia be ha ve s im i l a r ly .

C a r b o n i s a t i o n o f w o o l c a n c a u s e l o ca l is e d d a m a g e . W o o l u n d e r g o e s s o m e h y -

d r o lys i s be twe e n a c id i s ing a nd d r y ing s t e ps , e ve n a t r oom te m pe r a tu r e [40 ] . The

su r f a c e a c id r e m a in in g a f t e r c a rbon i s ing i s une ve n ly d i s t r ibu te d in the woo l m a ss

and co nse qu ent ly loca l i sed dam age i s caused [41 ] . Th ere i s a c r i t ica l poin t a t a

t e m p e r a tu r e o f 7 0~ in the d r y ing s t age a nd 120 ~ in the ba k ing s t a ge a bove wh ic h

wo ol hyd rolys is inc reases s igni f icantly . Oxy gen i s not d i rec t ly involved in hydrolys is

da m a ge to woo l du r ing c a r bon i s ing . L owe r d r y ing t e m p e r a tu r e s be f o r e ba k ing in

c a r bon i s ing m in im ise da m a ge to woo l f ib r e s . The a dd i t ion o f su r f a c t a n t i n the

carbo nis in g ba th resul t s in the even d is t r ibu t ion o f the ac id as a f i lm ove r the ent ire

su r f a c e o f the f ib re a nd c a n p r o te c t wo o l du r ing c a r bon i s ing [42 ] .

S om e t im e s c a r bo n i s ing i s done du r ing dye ing w i th 1 : 1 m e ta l c o m p le x dye sunde r s t r ong ly a c id c ond i tions , bu t th i s m e thod m a y p r oduc e se ve r e f ib r e da m a g e

a nd r e qu i r e s c a r e f u l c on t ro l o f dye ing c ond i t ions . F ib r e da m a ge s m a y a l so oc c u r

by d e c a t i s ing the dye d f a b r i c s unde r p r e ssu r e a nd he nc e d e c a t i s ing a t a tm osp he r i c

p r e s s u re i s r e c o m m e n d e d [ 4 3] .

M o d e m m e t h o d s o f b l e a c h i n g w o o l i s d i re c te d t o w a r d s t h e c o n t ro l o f c h e m i c a l

da m a ge s d u r ing the t r e a tm e n t . C he m ic a l da m a ge g e ne r a l ly oc c u r s due to e xc e ss ive

r a p id d e c om pos i t ion o f H20 2 . The r e a c t ion o f woo l w i th H20 2 i s r e l a t ive ly s low in

a c id ic c ond i t ion tha n tha t o f a lka l ine c ond i t ion . The p r e se nc e o f a c t iva t ing r e duc -

ing a ge n t s ( m e ta l s a lt s ) c an a l so e nha nc e r e a c t iv ity o f the no r m a l woo l s in p r e se nc e

of H20 2 a nd c a n l e a d to f ib re de g r a da t ion . Th e p r e c a u t ions a r e e xa c t ly the sa m e a s

those ne e de d in the b l e a c h ing o f c o tton w i th H20 2.

Du r ing ox ida t ive da m a ge to woo l som e o f the c ys tine c r os s - links ( the num be r

de pe n d ing on the c ond i t ions ) a r e sp li t a nd a re ox id i se d to c ys te i c a c id wh ic h c a n be

r e ga r de d a s a m e a su r e o f the de g r e e o f da m a ge [44, 45 ] . A poss ib l e m ode o f a tt a c k

ha s be e n sugg e s te d f o r the r e a c t ion o f pe r su lpha te ions w i th the pe p t ide g r oups[46 ]. The r e a c t ion o f woo l w i th pe r a c ids a nd p r oba b ly h ydr o ge n pe r o x ide i s c on -



3 5 6 D e g r a d a t i o n o f F i b r es A s s o c i a t e d w i t h C h e m i c a l P r e -T r e a t m e n t P r o c e s s e s

s ide r e d to y i e ld S - m onoxyc ys ty l a nd S , S - d ioxyc ys ty l r e s idue s [47 ] . A l though

su lph i t e ions r e a c t w i th woo l to sp l i t t he d i su lph ide l i nka ge s , d i s so lu t ion do e s no toc c u r . The r e a c t ion i s r e ve r s ib l e a nd the m a x im um e x te n t o f r e a c t ion t a ke s p l a c e a t

pH a r oun d 3 to 4 [48] . The m e c ha n i sm o f r e a c t ion se e m s to be nuc le oph i l i c a t t a c k

of the d i su lph ide b ond by e i the r the b i su lph i t e ( HS O3-) o r t he su lph i t e (S O3-- ) ion .

1 2 .6 D a m a g e o f S i lk D u r i n g P r e - t r e a t m e n t P r o c e s s e s

T h e r e m a y b e t h r ee t y p e s o f d a m a g e s o f s il k d u ri n g t he p r e -t r e a tm e n t p r o -

c e s se s . R e p e a t e d p r o c e s s e s a n d i m p r o p e r h a n d l i n g m a y c a u se m e c h a n i c a l d a m a g e s

due to c ha f ing a t t he s i lk f ib r e su r f a c e . B io log ic a l da m a ge s m a y o c c ur on s to r a ge ,

e spe c ia l ly in a non - de g um m e d s t a te , due to ba c te ri a . C he m ic a l da m a g e s m a y oc c ur

d u e t o i m p r o p e r c o n t r o l o f t h e v a ri o u s p a r a m e t e r s d u r i n g d e g u m m i n g a n d b l e a c h -

ing t r e a tm e n t s .

T h e c h e m i c a l b e h a v i o u r o f si lk t o w a r d s a c i d i s s o m e w h a t l ik e w o o l e x c e p t t h at

i t i s more readi ly a t tacked by s t rong ac ids . S i lk i s more res is tan t to a l l a lka l ie s

e xc e p t c a us t i c soda a nd c a us t i c po ta sh . P r o long bo i l ing o f si lk fib r es in wa te r a lone

wi l l p r odu c e s low d e gr a da t ion a n d hydr o lys i s . I n a c id o r a lka li , hydr o lys i s o f t he

pe p t ide c ha in o c c u r s w i th lo s s o f t e ns il e s t r e ng th o f the f ib re s . The e x te n t o f de g r a -d a t i o n d e p e n d s o n t h e p H o f t h e s o l u ti o n s a n d i s m i n i m a l b e t w e e n a p p r o x i m a t e l y

p H 4 . 0 a n d p H 8 .0 . U n e v e n d e g u m m i n g c a u s e s s p o tt e d b a t c h e s d u e to u n e v e n w e f t

m a te r i a l . L im e soa p r e s idue s m a y be p r e se n t on s i lk due to ha r d wa te r a nd poor

r in s ing show ing m e ta l spo t s a nd r us t pa r t i c le s .

Un c on t r o l l e d o x ida t ion o f b l e a c h in g ba ths c a n a t t a c k the s i lk f ib r e , t t yp oc h lo -

r i te , c h lo r ine d iox ide e t c . c a n c a use d i sc o lou r a t ion o f the f ib r e p r oba b ly due to the

ox id a t ion o f the ty r os ine r e s idue s . Hy poc h lo r i t e so lu t ions re nde r bo th f ib r ion a nd

se r i cin in so lub le to a n e x te n t de pe nd ing on the pH, be ing m or e e f f e c tive in a lka l ine

solu t ion (pH 10 .3), s l ight ly le ss in mi ld ly ac id (pH 4 .0 ), and not a t a ll in s t rongly

acid.

W he n s i lk is im m e r se d in hyd r oge n pe r ox ide so lu t ion , t he la t te r is a bso r be d to

a n e x te n t w h ic h i s i nde pe n de n t o f p H in the r a nge 2 .5 to 9.0 . Th i s m a y be due to the

f a c t t ha t the pe r ox ide c om bine s w i th a m ino g r oups a nd pe p t ide bond s o f s i lk f ib r e s

[49 ] . Pe r ox ide a l so c a use s r e duc t ion in ty r os ine c on te n t p r e sum a b ly due to the

sc i s s ion ing o f pe p t ide bon ds a t li nka ge s invo lv ing ty r os ine [50] . Ox ida t ion o fpe r a c e t i c a c id c a use s s c i s s ion a t a g r e a t e r ra t e tha n by hy dr oge n pe r ox ide , bu t l o s s




in w e igh t for a g iven r ise in flu id i ty is grea te r wi th hyd roge n peroxide than pe race t ic

ac id [51 ] . Th is i s be cau se tyro s ine in s i lk i s ox id ised to ac id ic group s .

1 2 .7 D a m a g e o f P o l y e s t e r D u r i n g P r e - t r e a t m e n t P r o c e s s e s

Poly e s t e r i s h igh ly r e s i s t a n t t o a c ids bu t a lka li c a n hyd r o lyse p o lye s t e r f ib re s .

The f ib re su r f a c e i s no t da m a ge d by t r e a tm e n t f o r 5 r a in a t sod ium hyd r ox id e c on-

cen t ra t ion as h igh as 38 .9 g /1 or a t 5 .2 g /1 for 2 h , bu t dam age does occu r i f f ibres

a r e t re a t e d w i th a 9 .1 g /1 sod ium hyd r ox ide f o r a t l e a s t 2 h [52 , 53 ]. The n um be r o f

hyd r oxy l g r oup s inc r e a se s due to a lka l ine hydr o lys i s , bu t the r e is som e d a m a ge to

the f ib r e su r f a c e . The f ib r e c r os s - se c t ion be c om e s m or e c om ple x a nd i t s a r e a de -

c r e a se s [54 ] . Due to a lka l ine hydr o lys i s we igh t lo s s oc c u r s , t oge the r w i th a n in -

c r e a se in de ns i ty , c r ys t a l li n i ty , a m in o a c id c on te n t , dye up ta ke a nd a b r a s ion r e s i s -

tance , an d a dec rease in in t r ins ic v iscos i ty , a s the con cent ra t ion o f a lka l i i s inc reased

[ 5 5] . I n a d d i ti o n , a m i n o l y s i s o f e t h y l a m i n e p r o c e e d s b y p e r m e a t i o n o f th e r e a g e n t

in to the f ibre and causes deg rada t ion , wh ich a f fec ts the br i t t leness , f lexura l f a t igue

r e s i s ta nc e , a nd t e ns i l e p r ope r t ie s o f the po lye s t e r [56] . The se c ha ng e s a r e e xp la ine d

in t e rm s o f c r ys t a l l in i ty a nd c r ys t a l l i te s iz e . As the tr e a tm e n t t im e inc r e a se s , de -

c r e a se in c r ys t a l l i n i ty a nd c r ys t a l l it e s iz e be c o m e m o r e p r onoun c e d . O n e x te ns ivet r e a tm e n t , t he p r op a ga t ion s t r es s c r a c ks on the f ib r e su r f a c e a nd f ina lly re su l t s i n

fibre breakage [57]. The addition o f cationic surfactant, dodecyldimethylbenzylamm onium

b r o m i d e , r e d u c e s t h e a l k a li n e h y d r o l y s i s o f p o l y e s t e r f ib r es s u b j e c te d t o N a O H

tr e a tm e n t by r e du c ing the c onc e n t r a t ion o f a lka li [58 , 59, 53 ] .

He a t - se t t i ng o f po lye s t e r f ib r e w i th s t e a m a lwa ys l e a ds to low m ole c u la r w e igh t s

tha n oc c u r w i th c onve n t iona l s e t ti ng . How e ve r , t he c l e a va ge o f po ly e s t e r f ib r es by

hydr o ly t i c de g r a da t ion on e xposu r e to s t e a m oc c ur s on ly a f t e r ve r y se ve r e e xpo-

su r e to s t e a m . G e ne r a l ly , c l e a va g e t a ke s p l a c e p r e do m ina n t ly a c r os s the f ib r e a x i s

to g ive i r r e gu la r l e ng ths be tw e e n sc i s s ions a nd the c l e a va ge d oe s no t a ppe a r to be

r e l a t e d to the s ign i f i c a n t phys ic a l phe no m e no n [6 0 -6 2 ] .

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39 D. Klee , P . Lers chm ach er and H. Z han , Tex t i l Prax is , 38 (1983) 1114 .

40 C. W ag an d and M. T. Pail thorp e, Te xti le Res. J ., 59 (1989) 322.

41 W . Zha o and M. T. Pail thorp e, Texti le Res. J. , 57 (1987) 39.42 W . Zha o and N. A. G. Johns on, Texti le Res. J ., 56 (1986) 741.

43 Blan kenb urg and Breuers , Schr i f tenre the des Deutsch en

W olforschu ngsins tu tes , 87 (1982) 402 .

44 E . E l~d , H. N ow om y and H. Z ahn , Kol lo id - Z . , 93 (1940) 50.

45 D. Klee , P . Lers chm ache r and H. Zah n , Tex t i l Prax is , 38 (1983) 1114 .

46 H. L. N eed les, Tex ti le Res. J . , 35 (1965) 298.

47 B. J . Sw eetm an et a l ., Proc. 3rd. Int . W ool Text . Res. Con f . , 11 (1965) 62.

48 G. Valk, Proc. 3rd. Int . W ool Text . Res. Conf . , 11 (1965) 375.49 P. Alex and er , D. Ca rter and C. Ear land , Bioche m . J. , 47 (1950) 251.

50 M. Na~canishi and K. Ko bay ash i, J. So c. Tex tile Cellulose Ind. Japan, 10 (1954)

128, 131 .

51 D .A . Stich and S. G. Sm ith , J . Tex ti le Inst . , 48 (1957) T 341.

52 J . Z hang and W. Zhu , Gaofenz i Tongxun , (1983) 295 .

53 J . Z han g and W . Zh u , Angew . Makrom ol . Chem . , 137 (1985) 249 .

54 B. F i l ipow ska and Z. Kubach i , Przeq l. Wolk . , 39 (1985) 11 1 , 118 .

55 K. J. Kim , Ha n ' guk Som yu Konghak hoech hi , 17 (1980) 151 .

56 M. S. Ell iso n et a l ., J . Appl. Polym . Sci . , 27 (1982) 247.

57 H. H. Cho , S . C. Choi and Y. H. Lee , Ha n 'g uk Som yu Kongh akho echh i , 21

(1984) 71.

58 V. A. Sh enai and N. K. N aya k, Texti le Dy er and Printer , 14 (1981) 25.

59 V. A. Shenai and N .K. Nay ak, Tex ti le Asia , 13 (8) (1982) 59.

60 S. M. M ilnera, P. Z. Sturg eon and D. J . Ca rlsson, Co lloid Polym . Sci . , 259

(1981) 474.61 J. Go ce~ et a l ., Invest . Inform . Text . Tens. , 27 (1984) 207.

62 W . Schafer , Tex t i lvered lung , 20 (1985) 3513 .



Cha pter 13

C O N S E R V A T I O N O F E N E R G Y A N D W A T E R , E C O N O M Y A N D E F F L U E N T

C O N T R O L I N P R E - T R E A T M E N T P R O C E S S E S

1 3 . 1 W a t e r C o n s u m p t i o n i n T e x t i l e I n d u s t r y

Te x t i l e indus t r y i s a le a d ing c ons um e r o f wa te r a nd i t r a nks a m ong t e n top wa te r

c o n s u m i n g i n d u s t ri e s [ 1 ]. T a b l e 1 3 . 1 s h o w s t h e a p p r o x im a t e c o n s u m p t i o n o f w a -

T A B L E 1 3 . 1

W a t e r C o n s u m p t i o n b y T e x t il e I n d u s t ry i n V a r io u s P r o c e s s e s [ 2 ]

Subs t ra te W a t e r c o n s u m p t i o n

kg /kg o f f a b r ic

C o t t o n 2 5 0 - 3 5 0

W o o l 2 0 0 - 3 0 0

N y l o n 1 2 5 - 1 5 0

R a y o n 1 2 5 - 1 5 0

Polyes te r 100-200

Acryl ic 100-200

te r for the process ing of va r ious tex t i le f ibres . Cot ton f ibres requi re the la rges t

a m oun t o f wa te r f o r it s p r e pa r a t ion . I n ge ne r a l , the wa te r c onsu m pt ion in a p r oc e ss

hou se i s a bou t th r e e t im e s the c on sum pt ion o f a ll o the r un it s pu t t oge the r ( Ta b le

13 .2 ). The wa te r c on sum pt ion in the b l e a c h ing se c t ion i s h ighe s t . The c onve n t iona l

T A B L E 1 3 . 2

W a te r C o nsu m pt ion Pa t t e r n in Te x t i l e M i l l s [3 ]

P r oc e ss W a t e r co n s u m p t i o n

(% of to ta l )

B le a c h ing , F in i sh ing 38

Dye ing 16

Pr in t ing 8

B o i l e r House 14

Hum id i f i c a tion ( sp inn ing) 6

Hum id i f i c a tion ( we a v ing) 9

Sani ta ry , Do m est ic e tc . 9



C onse r va t ion o f Ene r gy and W ater 361

p r ep a r a to r y p r o c es s es o f t ex t i le s n am e ly , d e s i z in g , s co u r in g , b l each in g , an d w as h -

ing are h igh ly wa ter con sum ing opera t ions and consequen t ly energy- in tens ive (Ta b le

13.3) .

T A B L E 1 3 . 3

C o n s u m p t i o n o f W a t e r a n d E n e r g y i n K i e r s a n d J - B o x P r o c e s s e s [ 4 ]

P r o ces s C o n s u m p t i o n o f w a t e r

1/kg

C o n s u m p t i o n o f st ea m

k g / k g

J - B o x

B l e a c h i n g

Des i z in g 3 0 . 2 5

W as h in g 2 0 0 . 35Sco ur ing 2 1 .75

W as h in g 2 0 0 . 3 0

Bleach in g 2 1 .00

W as h in g 4 0 0 . 60

Total 87 4 .20

Co n v en t io n a l k i e r - b o i l i n g 1 00 5 . 1 0

1 3 .2 I m p u r i t ie s in W a t e rT h e q u a l i t y o f w a t e r to b e u s ed i n a p r o ces s h o u s e d e c id es t h e u l t im a te q u a l i t y

o f c lo th l i k e w h i t en es s , b r i g h tn es s o f co lo u r e t c. T h e m a in im p u r i t i e s i n w a te r a re

tu r b id i t y an d co lo u r , i r o n an d m an g an es e , a lk a l i n i t y an d h a r d n es s . T h e q u a l i t y o f

wa ter r ece iv ed in the tex t i le mi l l s depends on the i r h i s to ry . M oor lan d w ater i s ac id ic

in n a tu r e . C o lo u r an d t u r b id it y i n w a te r m ay s t ain t h e fi b re . In p u r i t ie s i n w a te r m ay

d eac t i v a t e en zy m es d u r in g d es i z in g an d i n s o lu b i l i s e s t a r ch m a te r i a l w h ich m ay

d ep o s i t o n t h e f ab ri c . T h e Ca 2 an d M g 2 i o n s f r o m Ca(OH)2 , Mg (OH)2 , Ca CO 3 an d

M g C O 3 p r e s en t i n w a te r m ay co m b in e w i th s o ap d u r in g s co u r in g . T h e a lk a li s a l t

h av e n o o r v e r y l it tl e aq u eo u s s o lu b i l i t y an d o n ce d e p o s i t ed t h e h an d le , s ew ab i l i ty ,

k n i t t ab i l i t y an d w a te r ab s o r b a n cy o f t h e s co u r ed f ab r ic an d y a r n w i l l b e im p a i r ed .

Be s id es d i r t w i l l b e m o r e d i f f icu l t t o r em o v e f r o m th e t ex t il e s i n h a r d t h an i n s o ft

w a te r . Io n s o f h eav y m e ta l s ( ir o n , co p p e r , m an g an es e ) ac t a s ca t a ly s t in th e d eco m -

p o s i t io n o f b l e a c h i n g a g e n t s a n d c a u s e a c t i v a t e d a t t a c k w i th s u b s e q u e n t d e g r a d a -

t i o n o f f ib r e . I f t h e i r o n co n t en t o f t h e w a te r s u p p ly f o r r e s e r v io r o r d eep w e l l s i s

h igh , ox id a t ion and f i l t r a t ion un i t s mu s t be ins ta l led to r educ e i t s con ten t be lo w 0 .1p . p . m . , o th e r w i s e s u i t ab l e b l each in g au x i l i a r ie s m u s t b e ad d ed t o th e b l each b a th .



36 2 C o n se r v a t i o n o f E n e r g y a n d W a t e r

I n the a e r a t ion t e c hn ique , t he wa te r i s pu m pe d th r oug h the a e r at ion a ppa r a tus [5 ],

t he m e ta l i s ox id i se d to i t s i n so lub le f o r m a nd p r e c ip i t a t e s f r om the wa te r . I m -p r op e r w a te r m a y in so lub i l is e m e ta l ox ide du r ing m e r c e r i z ing a nd r e duc e a bso r -

ba n c y a nd lu s t r e . I n the dye ing s t a ge , m e ta l i ons m a y c om bine wi th som e dye s a nd

c a use du l l ing o f sha de . I m pur i t i e s in wa te r m a y a l so l e a d to p r e c ip it a t e on to bo i l e r

tube s f o r m ing sc a le s . As bo i l e r s c a l e f o rm s , h e a t t ra ns f e r a nd bo i l e r e f f i c ie nc y i s

r e du c e d f o r m ing ho t spo t s wh ic h in tu r n c a use we a ke n ing o f the bo i l e r t ube s l e a d -

ing to p ipe b low - ou t s a nd f a i lu r e s .

The qua l i ty o f wa te r i s j ud ge d by to t a l d i s so lve d so l id s ( TDS ) a nd ha r dne ss

wh ic h ge n e r a l ly va r i e s de pe n d ing on the loc a t ions a nd r e g ions . Ta b le 13 .4 shows

T A B L E 1 3 . 4

A c c e p t a b l e W a t e r C o n t e n t f o r P r o c e s s i n g [ 6]

Impur i t ie s Pa r t s pe r m i l l i on

Sil ica 0 .5-3

To ta l ha r dne ss ( C a C O 3 ) 0-25

Tota l a lka l in i ty ( C a C O 3 ) 35- 6 4Disso lv e d so l id s ( TDS ) 6 5 - 150

I ron (Fe), Cu, M n 0 .02-0.1

C o lour T r a nspe r a n t

Turbid i ty Clea r

pH 7-7 .5

the a ppr ox im a te ide a o f the l im i t o f wa te r qua l i ty su i t a b le f o r we t p r oc e ss ing o f

t e x t il e s . Wa te r ha r dne ss i s c a use d m a in ly by c a l c ium a nd m a gne s ium b ic a r bona te s ,c h lo r ide s a nd su lpha te s wh ic h c a n h a ve be e n a bso r be d by r a in wa te r a s i t pe r c o la t e s

t h r o u g h t h e v a r i o u s s t r a t a . W h e n h a r d w a t e r i s b o i l e d , t h e b i c a r b o n a t e s a r e

deco m po sed and prec ip i ta tes a s ca rbona tes and the ha rdness due to these sa lt s la rge ly

C a ( H C O 3 ) 2

M g ( H C O 3 ) 2

) C a C O 3 + C O 2 + H 2 0

), M g ( O H ) 2 + 2 C O 2

d i sa ppe a r s . Th i s type o f ha r dne ss i s c a l le d " Te m por a r y ha r dn e ss " a nd is the m a jo r

c a use o f s c a le f o r m a t ion in bo i l er s . " P e r m a n e n t h a r d ne s s" i s a s soc ia t e d wi th m e ta l

sa l t s such as n i t ra tes , ch lor ides , su lpha tes and pho spha tes wh ich a re so luble in w a te r



C o n s e r v a t i o n o f E n e r g y a n d W a t e r 3 63

a n d a r e n o t d e c o m p o s e d b y h e a t. T h e s u m o f t h e t e m p o r a r y a n d p e r m a n e n t h a r d n e s s

i s c a l l e d " t o t a l h a r d n e s s " . H a r d n e s s i s u su a l l y e x p r e s se d i n d e g r e e s a n d i s d e sc r i b e di n t e r m s o f e q u i v a l e n t s o f c a l c i u m c a r b o n a t e o r o x i d e . It is g e n e r a l l y c o n s i d e r e d

t h a t t h e m a x i m u m p e r m i s s i b l e l ev e l o f T D S a n d h a r d n e s s t o b e u se d i n we t p r o c e s s i n g

s h o u l d b e a b o u t 2 5 a n d 5 0 0 p . p . m , r e s p e c t i v e l y . W a t e r c o n t a i n i n g 0 -5 ~ E n g l i s h

h a r d n e s s i s c o n s i d e r e d t o b e so f t a n d o v e r 1 5 ~ i s h a r d .

1o E n g l i sh h a r d n e s s = 1 0 m g /1 o f C a C O 3 i n 0 .71

1o A m e r i c a n h a r d n e s s s = 1 m g /1 o f C a C O 3

1o G e r m a n h a r d n e s s - 1 0 r ag /1 o f C a O o r 7 .9 ra g/1 M g O

1 3 .3 W a t e r P u r i f ic a t i o n

C o n v e n t i o n a l s o f t e n i n g t r e a t m e n t p l a n t m a y n o t r e m o v e t h e i m p u r i t ie s i n w a t e r

t o t h e r e c o m m e n d e d p e r m i s s i b le l e v el . D e m i n e r a l is e d o r re v e r s e o s m o s i s t e c h n i q u e

i s n e e d e d f o r r e m o v a l o f T D S f r o m w a t e r b u t i s c o s tl y . W a t e r p u r i f i c a t i o n i n th e

p r o c e s s h o u s e n o r m a l l y c o n s i s ts o f f l o c u la t io n , s e d i m e n t a t io n , f i lt r at io n a n d i o n -

e x c h a n g e . H a r d w a t e r is n o r m a l l y s o f t e n ed u s i n g o n e o r c o m b i n a t io n o f m e t h o d s

t h e d e t a il s o f e a c h p r o c e s s i s g iv e n i n m a n y t e x t b o o k s .

1 3 . 3 . 1 S o d a - a l u m p r o c e s sH a r d w a t e r is f i rs t p u m p e d i n to t h e r e a c ti o n t a n k a n d t h e n a l u m i n i u m s u l p h a te i s

a d d e d t o it a s f lo c u l a n t . A b o u t 2 0 - 3 0 m i n i s a l l o we d t o r e a c t a n d t h e n t h e i m p u r i t i e s

a r e a l l o we d t o s e t tl e f o r a b o u t 3 0 m i n b e f o r e f i lt r a ti o n . M a n y f l o c u l a n t s n e e d a l k a li

4H 20 + 3N a2CO 3 + A12(SO4)3 --> 2Al(O H)3 + 3Na~_SO4 + 3 C O 2 + H 2 0

a s a n a s s i s t a n t f l o c u l a n t . I f a d d i t i o n a l a l k a l i is n o t a d d e d , t h e t o t a l a l k a l i n i t y i s

r e d u c e d a n d p a r t o f a l u m i n i u m s u lp h a te , b e i n g w a t e r s ol u b le m a y p a s s t h r o u g h t h e

f il te r . A s a l u m i n i u m h y d r o x i d e a n d m e t a l s p r e c i p i ta t e d o w n w a r d s , c l e a r w a t e r a r-r i v e s a t t h e to p a n d i s d e c a n t e d .

1 3 . 3 . 2 L i m e - s o d a p r o c e s s

I n t h is p r o c e s s l i m e a n d s o d i u m c a r b o n a t e a r e a d d e d to p r e c i p it a t e t h e c a l c i u m

a n d m a g n e s i u m s a lt s as te m p o r a r y h a r d n e s s.

C a ( H C O 3 ) 2 + C a ( O H ) 2 --> C a C O 3 + 2 H 2 0

M g ( H C O 3 ) 2 + C a ( O H )2 --> M g ( O H ) 2 + 2 C a C O 3 + 2 H 2 0

F o r p e r m a n e n t h a r d n e s s th e r e a c t io n s a re 9

C a S O 4 + N a z C O 3 ----> C a C O 3 + N a z S O 4

M gS O4 "+" Ca (OH )2 ~ M g(O H)2 + CaSO 4



3 6 4 Conservat ion of Energy and Water

C a S O 4 + N a 2C O 3 --4 C a C O 3 + N a 2S O 4

The s o f t e ne d w a t e r i s u s ua l l y s l i gh t ly a l ka l i ne w i t h 1 -4 ~re s i dua l ha rdne s s .1 3 .3 .3 B a s e e x c h a n g e p r o c e s s

W he n ha rd w a t e r is pa s s e d t h roug h a be d c on s i s t ing o f z e o l it e s , w h i c h a r e s yn -

t he t ic ma t e r i a l s ys t e ms c om pos e d o f c om pl e x s od i um, a l umi n i um a nd s il ic a t e sa l ts

( N a 2Z ) , t he c a l c i um a nd ma gne s i um i ons a r e e xc ha nge d . The d i s p l a c i ng r e a c t i ons

fo r t e mpora ry ha rdne s s a r e :

Ca (HC O3) 3 + Na2Z --4 C a Z + 2 NaH CO 3

Mg(H CO3) 3 + N a 2Z ~ M g Z + 2 N a H C O 3

F o r p e r m a n e n t h a r d n e s s t h e re a c t io n s a r e :

Ca SO 4 + N a 2Z - - , C a Z + Na2S O 4

Mg SO 4 + N a 2Z - ~ M g Z + N a 2 S O 4

The p roc e s s i s r e ve r s i b l e a nd t he be d ( N a2Z ) c a n be re ge ne ra t e d by pa s s i ng c onc e n-

t r a t e d s a l t s o lu t i on . Th i s m e t hod o f w a t e r s o f t e n i ng y i e l ds a ve ry s o ft w a t e r ( 0. 5 -1 o

ha rdne s s ) .

C a Z + 2N a C 1 -~ C aC 12 + N a 2Z

W a t e r s o f t e n i n g b y d e m i n e r a li s a ti o n s y s te m s c a n b e a c c o m p l i s h e d u s i n g e it h e rmi xe d be d ( bo t h c a t i on a nd a n i on r e s i n i n one be d) o r t w o be d s ys t e m ( r e s i ns

r e m a i n s e pe ra t e d a c c o rd i ng t o t he i r c ha rge s ) . The a c t i ve s i te s o f t he r e s i n s a r e l im-

i te d a nd t he s i te s a r e f i ll e d w he n w a t e r pa s s e s t h ro ugh t he s e c o l um ns a nd mu s t be

r e ge ne ra t e d a ga i n . The i r i on -e xc ha n ge c a pa c i t y i s g r e a t e r tha n t ha t o f z e o l it e .

1 3 . 4 E c o n o m y T h r o u g h E n e r g y C o n s e r v a t i o n

The t e x t i l e i ndus t ry c ons ume s bo t h e l e c t r i c a l a nd t he rma l e ne rgy . A l l t he fou r

m ajor c om m erc ia l energ y sources i . e . coa l , e l ec tr i c ity , o i l and gas a re u t i li s ed . Pow er

f rom h ydroe l e c t r i c , nuc l e a r pow e r a nd na t u ra l ga s a l so c on t r ibu t e s i m por t a n t s ou rc e

o f e ne rgy , s o l a r e ne rgy , b i o -ga s m a y be us e d fo r t e x t il e d ry i ng , f o r he a t i ng w a t e r ,

s i nge i ng , de s i z i ng , k i e r -bo i l i ng e tc . [ 7 -11 ] . A bo u t 55 t o 6 0 % e ne rg y c o ns um e d i n

t he t e x t i l e i ndus t ry i s u s e d i n va r i ous p r e - t r e a t me n t s t a ge s . Ta b l e 13 . 5 s how s t he

pa t t e rn o f s t e a m c o ns um pt i on i n a c om pos i t e t e x t i le mi l l. W e t p roc e s s i ng o f t e x -

t i le s c on s um e on l y a s ma l l p rop or t i on o f e le c t r ic a l e ne rgy ( = 15% ) m a i n l y fo r r un -

n i ng va r i ous p ro c e s s i ng ma c h i ne r i e s . Fue l i n t erms o f coa l o r o il is u s e d e x t e ns i ve l y

i n t he t e x t i l e i ndus t ry a nd t he rma l e ne rgy i n t he fo rm o f s t e a m ge ne ra t e d i n t hebo i l e r i s s upp l i e d t o t he va r i ous e qu i pme n t t h rough p i pe s . S e ve ra l p l a n t s / ma c h i n -



C o n s e r v a t i o n o f E n e r g y a n d W a t e r 365

T A B L E 1 3 . 5

S t e a m C o n s u m p t i o n i n a C o m p o s i t e T e x t il e M i ll

D e p a r t m e n t S t e a m c o n s u m e d ( % )

Hum id i f i c a t ion 10

Sizing 15

B o i l e r house ( a ux i l ia r i e s ,

b low dow n e t c .) 0 5

L e a k a g e a n d a v o i d a b l e w a s t a g e s 1 0

W e t p r o c e s s in g 6 0e r y d e v e l o p m e n t s a n d t e c h n o l o g i c a l a d v a n c e m e n t s h a v e b e e n w i t n e s s e d o v e r th e

l a s t de c a de to m e e t the c ha l l a nge s f o r c onse r v ing bo th the r m a l a nd e l e c t r i c a l e n -

e rg y . S o m e 0 f t h e i m p o r t a n t a p p r o a c h e s a r e g i v e n b e l o w .

1 3 .4 .1 E f f i c ie n t g e n e r a t i o n o f e n e r g y a n d m i n i m u m c o n s u m p t i o n

The b o i l e r i t s e l f shou ld be ve r y e f f i c i e n t t o ge ne r a t e s t e a m a nd f o r th i s p r e pa r a -

t ion o f o il , a ir to f ue l r a t io , s t a c k t e m pe r a tu r e o f f lue ga se s , c o nve r s io n o f f u r na c e

o i l t o L S HS o i l, m a x im um c ond e nsa te r e c ove r y , c l e a n ing o f the f ir e s ide , r e p la c e -

m e n t o f o ld bo i l e r s e t c. a r e the va r ious im p or t a n t f a c to r s to be t a ke n c a r e - o f . Fa c -

t o r s r e s p o n s i b l e f o r o p t i m u m c o n s u m p t i o n o f s t e a m s u c h a s s u p p l y o f s t e a m a t

c o r r e c t p r e s su r e , p r ov i s ion o f p r e s su r e r e duc ing va lve s , wa te r s e pa r a to r s in s te a m

l ine s f o r supp ly o f d r y s t e a m s a t r e qu i s i t e p r e s su r e , s e l e c t ion o f t r a p o f righ t t ype

a nd s i z e f o r e f fi c i e n t r e c ove r y o f c onde nsa te e t c. shou ld be c o ns ide r e d f o r the sa v -

ing o f the r m a l e ne r gy .

1 3 .4 .2 M e c h a n i c a l r e m o v a l o f w a t e r b e f o r e d r y i n g

U s e o f s q u e e z i n g s y s t e m s t o p i c k - u p 4 0 - 5 0 % w a t e r b y u s i n g K u s t e r m a n g l e[ 12 ], R o to m a t w a sh in g m a c h ine [ 13 ], K le ine we f e r s Ja e gg l i B io f l e x [ 14 ], Aqu i l a n

a i r c ush ion sque e z ing [ 15] a nd R o be r to r o l l s i n p l a c e o f r ubb e r r o l ls [16] a r e som e

of the m a c h in e r i e s r e l a t e d to e f f ic i e n t r e m ova l o f w a te r /p r oc e ss l i qu ids o r c on -

t r o ll e d a p p l i ca t io n . U s e o f v a c u u m i m p r e g n a t i o n t e c h n i q u e [ 1 7, 1 8] a n d v a c u u m

r o l l e r e x t r a c to r [19] c l a im 7 5% f ue l s a v ing by the use o f va c uum f o r e xpu l s ion a nd

e xp a ns io n o f a i r f r om the f a b r ic f o r be t t e r a nd un i f o r m im p r e gna t ion . U se o f suc -

t ion s lo t f o r m e c ha n ic a l r e m ova l o f w a te r f o r fue l s a v ing i s a l so re po r t e d [20] .

1 3 .4 .3 I n c r e a s e d e f f ic i e n c y o f d r y i n g a n d h e a t - s e t t in g

T h e t o ta l e n e r g y c o n s u m e d i n w e t p r o c e s s i n g m a y b e i n h e a ti n g w a t er , 3 5 - 6 5 % ;



36 6 C o n s e r v a t i o n o f E n e r g y a nd W a t e r

drying , hea t - se t t ing or baking , 25-60% ; l iquor c i rcula tion , 10% ; the res t is consu me d

in m ov ing a nd ha nd l ing f a b r ic a nd so on . I nc r e a se d e f f ic i e nc y o f d r y ing i s a c h ie ve dby im pr ov e d the r m a l in su la t ion , r e duc e d l e a ka ge s , a pp r opr ia t e s t e a m p r e s su r e a nd

pr op e r s t e a m l ine d i s t ribu t ion . U se o f r a d io - f r e que n c y t e c hn ique in d r y ing c a n be

use d a s low e ne r gy e l e c t r om a gne t i c r a d ia tion . H igh spe e d he a t - se t t i ng sys t e m c a n

b e d e v e l o p e d b y t h e u s e o f m i x t u r e o f a ir a n d s u p e r h e a te d s t e a m a n d s w e l li n g

c om pou nd s l ike po lye thy le ne g lyc o l l ic e the r in p l a c e o f c onve n t iona l ho t a i r c a n be

use d a nd 6 0 - 7 0 % sa v ing in the r m a l a n d e l e c t r ic a l e ne r gy i s thus , poss ib l e .

1 3 . 4 .4 R e d u c e d l i q u o r to m a t e r i a l r a t i o

Ge ne r a l ly , m a c h ine s w i th b igge r t r ough s i z e s c a use m a jo r wa s ta ge o f wa te r a nd

c he m ic a l s . V- sha pe d t r oughs g ive be t t e r im pr e gna t ion t im e wi th low l iquor r a t io

and the qua nti ty o f s team requ ired for heating the l iquor is a lso less . Fur ther , switching

ove r to s e m i - c on t inuous o r c on t inuous ope r a t ions c a n a l so l e a d to r e duc e d l iquor

r a t io , t im e a nd c os t . The sp r a y ing o f l i quor, n ip pa dd ing , f oa m a pp l i c a t ion , m in i -

m um a pp l i c a t ion t e c hn ique s e t c. a r e al so the va r ious a ppr oa c h e s in th i s d i re c t ion .

1 3 .4 . 5 E f f i c ie n t h e a t r e c o v e r y

I n the p r oc e ss house wa te r i s ge ne r a l ly he a te d f r om r oom te m pe r a tu r e to 8 0 -9 0~ a nd a t t he e nd o f the p r oc e ss w a te r is r un a w a y in to the d ra in . Th i s is a bso -

l u te l y u n e c o n o m i c . M a n y o f t h e m o d e m m a c h i n e is e q u i p p e d w i th e f f e ct iv e h e a t -

e xc ha nge r s , i n wh ic h the ou t f lowing ho t wa te r he a t s up the in f lowing c o ld wa te r

a nd i s on ly the n d i sc ha r ge d in to the d r a in .

An o the r po ss ib l e sou r c e o f r e c ove r a b le he a t i s t he wa s te he a t c on ta ine d in the

c onde nsa te . O wing to the c onde n sa t ion p r ob le m s , t he f lue ga s t e m pe r a tu r e i s a r ound

20 0 ~ I f t he f lue ga se s a r e c oo le d down f rom 200 ~ to 50 ~ by bo i l e r f e e d wa te r

o r p r oc e ss in g wa te r , t he re su l t i s c ons ide r a b le s a v ing in e ne rgy .

Ex ha u s t a i r he a t r e c ove r y un i t s c a n a lso be e m p loye d a s the e ne r gy c a r r i e r m a y

be ga s o r a i r . Dur ing he a t - se t t i ng o f t e x t i l e s on s t e n te r f r a m e s e m is s ion o f c om -

pou nd c a pa b le o f va po r i sa t ion m a y oc c ur a nd the flue ga se s is e sc a pe d f r om the

c h im n e y . The a i r e xha us te d f r om the s t e n te r i s fe d th r ough a n in su la t ed a i r duc t i n to

the bo i l e r house , wh e r e toge the r w i th the q ua n t i ty o f a ir r e qu i r e d f o r c om bus t ion , i s

pa s se d th r ough a b lowe r sys t e m in to the the bo i l e r . Whe n the bo i l e r c om e s in to

opera t ion , c lean f lushing energy i s draw n- in through an in take v ia a swi tch equippedwi th a n a u tom a t i c d r op f la p . The swi t c h c ha n ge s ov e r to e xha u s t a i r a f t e r t he bu r n -




in g u n i t h a s i g n i t ed . Ab o v e t h e r o o f is an o p en b u f f e r ch im n ey , t h r o u g h w h ich t h e

ex ces s ex h a u s t a i r can e s cap e o r t h e f re s h a i r r eq u i r ed f o r f u rth e r co m b u s t io n canbe d ra w n- in [21 ] .

1 3 .4 .6 H e a t r e c o v e r y f r o m p r o c e s s e f f l u en t s

T e x t i le p r o c e s s i n g h o u s e s d i s c h a r g e a lo t o f c o n t a m i n a t e d h o t w a s t e w a t e r a n d

em i t s m o k e , w h ich a r e s o u r ces o f w a t e r an d a i r p o l lu t i o n . T h e r e i s an i n t e r- r e la t i o n -

s h ip o f en e r g y r eco v e r y an d en v i r o n m en ta l p r o t ec t io n . In c r eas e d t em p e r a tu r e h av e

n eg a t iv e e f f ec t o n t h e o r g an i s m s l i v in g i n w a te r an d d es t ro y t h e eco lo g i ca l s y s tem .

T h e w as t e w a te r an d ex h au s t g as can b e u s ed t o h ea t u p c l ean , co ld w a te r an d t h i s

can b e r e tu r n ed t o t h e p r o d u c t io n p r o ces s .

1 3.5 E c o n o m y T h r o u g h W a t e r C o n s e r v a ti o n

I t i s a lw ay s e s s en t i a l t o u s e l e s s q u an t i t y o f w a t e r w i th p r o p e r q u a l i t y f o r a

p a r t i cu l a r p r o ces s . T h e co s t o f w a t e r i s in c r eas in g an d i n o rd e r t o co n s e r v e en e r g y i t

i s n ece s s a r y t o r ed u ce t h e w a te r co n s u m p t io n i n t h e p ro ces s h o u s e . T h i s i s ex p ec t ed

to r e s u l t i n s av in g s o f ch em ica l s , w a t e r , r ed u ce t h e e f f l u en t q u an t i t y an d r e l a t ed

p r o b l e m s o f t r e a tm e n t a n d d i s p o s a l. M a c h i n e r i e s w i t h n e w d e s i g n s a n d n e w p r o -

c e s s te c h n i q u e s a re d e v e l o p e d f o r m i n i m i s i n g t h e r e q u i r e m e n t o f w a te r .1 3 . 5 . 1 M i n i m i s i n g l i q u o r t o m a t e r i a l r a t i o

R e d u c e d l iq u o r r at io n o t o n l y r e d u c e s w a t e r c o n s u m p t i o n b u t a l so r e d u c e t he

q u an t i t y o f e f f lu en t t o b e t r ea t ed . T h e l i q u o r r a ti o i n k i e r an d p e r o x id e b o i l , u s u a l ly

r an g es f r o m 2 . 5 t o 4 . In p r e s s u r e b o i l s , t h e w a te r co n s u m p t io n f o r co o l in g an d

w a s h in g i s fo u n d to v a r y f r o m 6 t o 9 li t r e s /k g o f c lo th . I t is p o s s ib l e t o r ed u ce t h e

w a te r co n s u m p t io n b y ab o u t 2 5 % b y r eg u l a t i n g th e w a te r p a r t icu l a r ly a t t h e tim e o f

co o l in g an d w a s h in g o p e r a t i o n s w i th t h e h e lp o f w a te r m e te r o r tim er . T h e a s p ec t o f

l iquro r a t io i s a l r eady d iscusse d wh i le descr ib ing the conserva t ion o f energ y th rough

p l a n t a n d m a c h i n e r y m o d i f i c a ti o n .

1 3 . 5 . 2 M i n i m i s i n g w a s h l i q u o r

W a s h i n g m a c h i n e s a re t h e m a j o r c o n s u m e r o f w a te r . G e n e r a ll y o l d ty p e o f w a s h -

in g m ach in es l i k e s l ack an d t i g h t r o p e r eq u i r e m o r e q u an t i t y o f w a t e r f o r w as h in g .

C o u n t e r - c u r r e n t p r in c i p l e s o f w a s h i n g , a q u a t e x w a s h i n g , b e a m a n d s u c t io n w a s h -

in g , p o w er f u l j e t w i th p u m p s an d v ib r a to r s, h o r i zo n t a l o r i n c l i n d w as h e r s e t c . w i l l

n o t o n l y i n c r e a se t h e w a s h i n g p e r f o r m a n c e b u t a l so d e c r e a s e th e w a t e r c o n s u m p -

tion.



368 C o n s e r v a t i o n o f Energy and W ater

1 3 . 5. 3 R e - u s i n g r i n s in g b a t h w a t e r

W a te r a nd he a t e ne r gy c onsum pt ion , t oge the r w i th e ff lue n t a c c um ula t ion c a n ber e du c e d in ba tc h type b l e a c h ing o f t e x t i le s by r e -us ing r in s ing a nd t r e a tm e n t ba ths

on the c oun te r f low p r inc ip le [22 ] . Th i s sys t e m ha s be e n pa te n te d unde r the na m e

B le a c hs ta r . Due to the be t t e r u sua ge o f the ind iv idua l ba ths , l a r ge qua n t i t i e s o f

c l e a n w a te r a nd he a t e ne r gy a r e s a ve d .

1 3 . 5 .4 D i r e c t s t e a m i n j e c t io n

For r e duc ing f l e sh wa te r r e qu i r e m e n t in a bo i l e r, d i r e c t s t e a m in j e c t ion in j i g -

ge r s a nd o the r e qu ipm e n t m a y be re p la c e d w i th ind i r e c t he a t ing sys t e m . Th e c on-

t inuous m a c h ine s o f f e r, be s ide s r e duc t ion in qua n t i ty o f wa te r w i th be t t e r wa sh ings

a nd l a bo ur r e qu i r e m e n t , p r oduc e m or e e ve n qu a l i ty o f f a b ri c . B y p r ope r c l e a n ing

a nd se qu e nc ing one c a n avo id down t im e du r ing c on t inuous p r oc e ss ing ope r a t ions .

1 3 . 6 E c o n o m y T h r o u g h P r o c e s s M o d i f i c a t i o n

P r o c e s s m o d i f i ca t i o n s /d e v e l o p m e n t s f o r m i n i m i s in g e n e rg y c o n s u m p t i o n i n th e

p r e - t r e a tm e n t p r o c e s s e s a r e v e r y i m p o r t a n t a n d s o m e o f t h e m a j o r d e v e l o p m e n t s

a r e b r i e f ly m e n t ione d .

1 3 . 6 . 1 M a t h e r a n d P l a t t ' s V a p o r l o c b l e a c h i n gVa por loc sys t e m i s a c on t inuous wa sh ing a nd b le a c h ing un i t w i th a r e a c t ion

c ha m be r f o r s c our ing und e r s te a m p r e s su r e o f a bou t 30 - 40 p . s. i, a t 130 -140 ~ f o r

6 0 - 8 0 se c, f o l lowe d by wa sh ing a nd pe r ox ide b l e a c h ing in a no the r c ha m be r . C o n-

s ide r a b le s a v ings in s t e a m , t im e , l a bo ur a r e a c h ie ve d . On ly 3 - 7 m in i s r e qu i r e d f o r

s c o u r i n g a n d b l e a c h in g . R e d u c i n g t h e t im e o f tr e a tm e n t b y m o d i f y i n g t h e p r e s s u re

kie r boi l in g for 2-6 h a t 15-25 lb / in 2 in pres enc e o f sod ium sulphi te in the sco ur ing

b a t h i s r e c o m m e n d e d [ 23 ].

1 3 . 6 . 2 J - B o x b l e a c h i n g

Du Pon t C o . ha s de ve lope d a two m inu te s b l e a c h ing p r oc e ss [24 ] f o r he a vy

f a b r i c s u s ing H 20 2 a t ve r y h igh pH va lue s us ing a spe c ia l f o r m ula t ion to p r e ve n t

u n d u e d e c o m p o s i t i o n o f p e r o x i d e a n d d a m a g e o f f ab r ic d u r i n g t h e p ro c e s s .

1 3 . 6 . 3 S o l v e n t S c o u r i n g

" M a r k a l P r o c e s s " d e v e l o p e d b y I C I f o r d e s i z i n g a n d s c o u r i n g o f f a b r i c i n -

vo lve s the t re a tm e n t o f a suspe ns ion o f e nz ym e , TC E a nd su r f a c t an t so lu t ion [25 ].

Th e mate r ia l a f te r t r ea tmen t for 10-20 sec passes through a s teaming cham ber wh erethe so lve n t is f la she d - o f f . Abo u t 8 0 % sa v ing in s te a m c onsu m pt ion i s r e po r t e d .



C onse r va t i on o f Ene r gy and W ater 369

1 3 .6 .4 C o l d b l e a c h i n g

A c o ld b l e a c h ing m e thod i s r e po r t e d in wh ic h de c o m p os i t ion o f N a C 10 2 i s c a use dby a c id i f i c a t ion o r by a dd i t ion o f r e duc ing a ge n t [26] . S od ium hy poc h lo r i t e i s a n

in te r m e d ia t e in the r e l e a se o f a c t ive c h lo r ine d iox ide . A c om bina t ion o f b i su lp h i t e

wi th a n a lde hyde i s s a id to in i t i a t e the c o ld b l e a c h ing a c t ion a nd p r a c t i c a l ly no

thermal energ y i s r equi red . The use ofaze t ropic /em uls ion based sc out ing cum bleach-

ing f o r m ula t ion he lps in p r oc e ss ing a t r oom te m pe r a tu r e . Th i s p r oc e ss u se s a ho t

w a sh a t no t l e s s tha n 7 0~ to a c h ie ve the r e qu i r e d r e su lt . In the c o ld pa d - ba tc h

m e thod , t he use o f pe r ox ide , su lpha te s a nd som e a c c e le r a to r s l ike u r e a , g luc ose ,

pe n ta - a c e ta t e e t c . c a n c a use c ons ide r a b le s a v ings in e ne r gy , wa te r a nd l a bour .

1 3.6 .5 C o m b i n e d p r o c e s s e s

S e ve r a l s ing le s ta ge c om bine d p r e - t r e a tm e n t p r oc e sse s a r e d i sc usse d in C ha p te r

11 to m in im ise the e ne r gy c o nsum pt ion . I n r e c e n t ye a r s the r e ha s be e n a t re nd to

s a v e l a b o u r a n d e n e r g y b y c o m b i n i n g d i f fe r e n t p r o c e s s e s w i t h d y e i n g o p e r a ti o n s .

The c om bine d m e r c e r i z ing a nd sc our ing p r oc e ss c ons i s ts o f im pr e gna t ing the f a b ri c

wi th c a us t i c soda o f m e r c e r i z ing s t r e ng th a t e l e va te d t e m pe r a tu r e w i th a s t e a m ing

un i t w i th in the ho t m e r c e r i z ing se c t ion [27] . In the B r uc k ne r s R e m a f la m e Pr oc e ss[28] f o r c om bine d d r y ing a nd f in i sh ing , a m ix tu r e o f m e tha no l a nd w a te r is a pp l i e d

to the f a b r i c a long w i th f in i sh ing so lu t ions . As the f a b ri c i s m ov e d r a p id ly u pw a r d

t h r o u g h t h e d r y i n g c h a m b e r , m e t h a n o l i s i g n it e d , t h e s o l u ti o n b u m s a w a y a n d t h e

f a b r ic i s l e f t w i th l e s s s tha n 4% m ois tu r e . R e m a f la m e d r ye r s ha ve be e n c l a im e d to

g ive f ue l e f fi c i e nc y a s h igh a s 7 2% a s c om p a r e d to 50 % f o r c onve n t iona l d r ye r s .

1 3 .6 .6 S h o r t e n i n g o f p r o c e s s s e q u e n c e

T h e t i m e o f v a r io u s p r e - t r e a tm e n t p r o c e s s e s c a n b e r e d u c e d b y j u d i c i o u s a p -

p r o a c h o f th e s h o r t e n i n g o f p r o c e s s s e q u e n c e w i t h o u t c o m p r o m i s i n g t h e q u a l i ty o f

g o o d s . T h e h e a t - s e t t i n g s p e e d c a n b e i m p r o v e d b y m a k i n g u s e o f s u p e r - h e a t e d

s t e a m a n d s o m e s w e l l in g c o m p o u n d s i n s te a d o f h o t a ir . G r e y m e r c e r i z a ti o n c a n

r e d u c e t h e n u m b e r o f d ry i n g o p e r a ti o n s . R u n n i n g t w o o r m o r e e n d s s i d e b y s id e o r

sup e r im pos e d on m a c h in e s l ike she a r ing , c r opp ing , c ha in le s s m e r c e r i z e r , c y l inde r

d r y ing r a ng e e t c. c a n inc r e a se the p r oduc t ion . Hy dr ose t t ing o f syn the t i c f ib re s a nd

i t s b l e n d s a t H T / H P b e a m d y e i n g m a c h i n e c a n r e d u c e t h e e n e r g y c o n s u m p t i o n .

C o m bine d op t i c a l b r igh te n ing a nd he a t - se t t i ng f o r syn the t i c fib r e fa b r i c s a nd c om -b i n e d b l e a c h i n g a n d o p t i c a l w h i t e n in g a r e c o m m o n l y e m p l o y e d .



3 70 C o n s e r v a t i o n o f E n e r g y a n d W a t e r

1 3 . 7 P o l l u t i o n A s p e c t s i n P r e - t r e a t m e n t P r o c e s s e s o f T e x t i le s

1 3 .7 . 1 W a t e r a n d a i r p o l l u t i o nT h e tw o m a in s o u r ces o f p o l l u t i o n i n ch em ica l p r e - t r ea tm en t o f t ex t il e s a r e

w a te r p o l l u t i o n an d a i r p o l l u ti o n . W ate r p o l l u t i o n i s m a in ly a t t r i b u t ab le t o t he v a r i -

o u s w a s t e s t r eam co m in g o u t o f t h e p r e - t r ea tm en t o p e r a t i o n s l ik e d es i z in g , s co u r -

in g , b l eac h in g e t c. Mo r eo v e r , t h e b lo w d o w n w a te r f ro m th e b o i l e r s an d t h e e f f lu -

en t d i s ch a r g ed f r o m th e w a te r t r ea tm en t p l an t s a l s o co n t r ib u t e t o th e w a te r p o l l u -

t io n . A i r p o l l u t i o n m a in ly co m es f r o m th e b o i l e r s w h ich a r e u s ed to p r o d u ce h e a t

en e r g y r eq u i r em en t s f o r w e t p r o ces s in g . T h e ex t en s iv e u s e o f co a l , o i l , g a s f o r

indu s t r ies has led to the a ir po l lu t ion . Po l lu ted a i r con ta ins co t ton du s t , CO, n i t rous

o x id e (N O ) , s u lp h u r o x id es (SOx ), CO 2, CH 4, ch em ica l v ap o u r , v a r io u s o x id a t i o n

co lo u r s , ch lo r in e v ap o u r , k e r o s in e , v a r io u s h y d r o ca r b o n s an d p a r t i cu l a t e s i n t h e

a tm o s p h e r e . T h e w o r s t co n d i t i o n f o r h u m an h ea l t h is t h e co m b in a t i o n o f p a r t i cu -

la tes co n ta in ing SO 2. Ge nera l ly , a i r po l lu t io n f rom indus t r ia l fue l bu rn ing and pro-

cess ing em iss ion con t r ibu te to abou t 30% of to ta l a i r po l lu t ion . In case o f indus t r ies

s i t u a t ed n ea r h o u s in g co lo n i e s , th e p e r m i s s ib l e l im i t o f an y h a r m f u l m a te r i a l i n ai r

is mentioned as ~/100o f th e M AK v a lu e . I f t h e v a lu es a r e h ig h e r t h an t h is p e r m i t tedl ev e l , an a i r p u r i f i ca t i o n s y s t em w i l l h av e t o b e i n st a ll ed . Us u a l ly t h e e m i s s io n s a r e

d u c t ed aw ay b y m ean s o f a t a ll ch im n ey to m in im i s e t h e im p ac t o f a i r p o l l u t an t s.

Gr ee n h o u s e g as es l ik e CO 2, CH 4 an d N zO e t c . t r ap t h e ea r th s h ea t , r a i s i n g a tm o -

s p h e r i c t em p er a tu r e . T h e im p ac t w o u ld b e v a r i ed an d u n p r ed i c t ab l e . A k ey e f f ec t

m a y b e r i s i n g o f s e a le v e l b y a r o u n d 5 0 c m s b y 2 1 0 0 b e c a u s e o f e x p a n s io n d u e t o

h e a t a n d m e l t in g o f g la c i er s. T h i s m a y b e c o m e a c a u se o f s u b m e r s io n o f lo w l y in g

a r eas an d d i s p l acem en t o f a r o u n d 80 m i l li o n p eo p le . T h e m a in cu lp r i t c au s in g g lo -

b a l w ar m in g i s CO 2, w h o s e co n t r i b u t i o n i s ab o u t 87% an d h en ce CO~ em is s io n is

r eq u i r ed t o b e co n t a in ed . T ab l e 1 3 .6 s u m m er i s e s t h e p o s s ib l e p r o b l em s in en v i r o n -

m en ta l co n t r o l l i k e ly t o b e c au s ed b y i n d iv id u a l s t ep s in t h e p r o d u c t io n o f tex t i le s .

Ai r p o l l u t i o n d u e t o s co u r in g an d b l each in g o p e r a t i o n s a r e co n s id e r ed t o b e n eg l i-

g ib l e a s n o t m an y v o l a t i l e p r o d u c t s a r e u s ed a t h ig h t em p er a tu r e s . Ac t i c ac id i s

v o l a t i l e an d r ead i ly eav p o r a t ed i n t h e ch am b er . I t c an b e r ep l aced b y c i t r i c ac id

w h ich i s n o n - v o l a t i l e an d a l s o w i ll b e r eq u i r ed i n a le s s e r q u an t i ty .

T o m i n i m i s e w a s t e w a t e r p o l lu t io n s o m e o f t h e m o s t f re q u e n t ly u s e d c h e m i c a l sh av e a l r ead y b een e i t h e r b an n ed b y l aw o r v o lu n t a r i l y w i th d r aw n . T h e r ed l i s t ed



Co n serv a t io n o f E n erg y a n d W a ter 371

T A B L E 1 3 . 6

E n v i ro n m en t a l P ro b l ems a t V ar i o u s S t ag es o f Ch em i ca l P ro ces si n g o f T ex t il e s [ 29 ]Proce ss ing s t ep W as te wa ter po l lu t ion Ai r po l lu t ion

Spinning/Texturising N o H ea t en e rg y

(y a rn p ro d u c t i o n ) g i v en o u t

dry s t ep

W eav i n g Lead s t o p o l l u t io n H ea t en e rg y

(wind ing /dry) l a t e r on des iz ing

(warp ing /dry)

(s izing/wet)

D ry i n g

Chem ical processing

Si n g e in g N o H ea t en e rg y

Des iz ing 50% to ta l load No

Sco u r i n g /b leach i n g 2 0% t o ta l l o ad N o

D y e i n g D y e s , C h e m i c a ls S o m e

P r in t in g D y es , Ch em i ca l s, T h i ck en e r s So m e

Fin i sh ing (Con vent iona l / Na tura l and syn the t i c Appre c iab le

s p ec ia l ) p o l y me rs , ch em i ca l s

ch emi ca l s , w h o s e p re s en ce o n a t ex t i l e p ro d u c t co n s i d e red a s d an g e ro u s can b e

d i v i d ed i n to fo l l o w i n g g ro u p s :

( i) Pen tach lo roph eno l - use d as p rese rva t ive s fo r gum s , s i z ing agen t s , fung i -

c ides , ro t p roof ing agen t s . I t s range l imi t is 0 .05 p .p .m , to 0 .5 p .p .m.

( ii ) H ea v y m e t a l s - p r e s en t in b u t t o n s , d yes , an t is ep t ic s , f u n g i c id es , au x i li a -r i es , a f t e r - t rea t ing agen t s . I ts range l im i t is 0 .0001 to 100 m g/kg .

( ii i) T o x i c p es t i c i d es - t o p rev en t p e s t a t t ack in cu l t iv a t i o n o f w o o l an d co t t o n ,

0 .5 to 5 mg /kg .

( i v ) F o rma l d eh y d e - r e s i n f i n i s h i n g , d y e a f t e r - t r ea t men t s , p r i n t i n g a s s i s t an t s

e tc . , 20-300 p .p .m.

(v) A zo d y es - t h o s e w h i ch co u l d r e l ea s e li s ted ca rc in o g en i c a mi n es , d u r i n g

red u c t i v e c l eav ag e (Ban n ed ) .

(v i ) Halogen car r i e rs - used in the dye ing o f d i sperse dyes on po lyes te r , 200

m g /k g fo r v o l a t il e o rg an i c h e l o g en s .

(vi i) Ch l o r i n e b l ea ch i n g - t o b e av o i d ed u n d e r s o m e eco l ev el s .




1 3 .7 .2 P a r a m e t e r s f o r a s s e s s m e n t o f h a r m f u l m a t e r ia l s i n w a s t e w a t e r

I t i s an es tabl i shed fac t tha t indus t r i es produ ce s igni f i cant quan t i t ie s o f con tam i-na n t w a s t e w a t e r w h i c h a r e d i s c ha rge d t o mun i c i pa l gu t t e r s , ope n l a nds , r i ve r s ,

nu l l a h a nd ponds a nd oc e a n a nd c a us e c ons i de ra b l e po l l u t i on p rob l e ms . Po l l u t i on

i n s ome pa r t s o f the w o r l d ha s r e a c he d a le ve l c l o s e to e c o l og i c a l c a t a s t rope a nd a l l

c oun t r i e s a r e ti gh t e n i ng c on t ro l on e nv i ronm e n t a l po l l u ti on . I t i s no w e s s e n t ia l t ha t

t he w a s t e w a t e r be t r e a t e d be fo re be i ng d i s c ha rg e d t o t he s e w e ra ge s y s t e m a nd ha s

t o be b i o l og i c a l l y de g ra da b l e . The s e ha rmfu l s ubs t a nc e s a r e a s s e s s e d t oge t he r a s

s ome pa ra me t e r s ( Ta b l e 13 . 7 ) w h i c h c a n be e va l ua t e d by s t a nda rd t e s t me t hods .

T A B L E 1 3 . 7

P a r a m e t e r s f o r A s s e s s m e n t o f H a r m f u l M a t e r i a l s i n W a s t e W a t e r [ 30 ]

P a r a m e t e r E s t i m a t i o n m e t h o d C onc e n t r a t i on

(unit)

B O D O x i d a t i o n b y a e r o b i c m i c r o - o r g a n i s m m g 0 2 / 1

C O D O xi da t i on w i t h K 2Cr20 7 m g 0 2 / 1

TO C C a t a l y t ic bu rn i n g m g C / 1

D O C C a t a ly t ic b u r n i n g m g C / 1

A O X A d s o r p t i o n o n a c ti v e c a r b o n g g x / 1

N t o t a l C o l o r i me t r i c e s t i ma t i on m g N / 1

P to ta l Prec ip i t a t ion m g p / 1

Phys i c a l , c he m i c a l , phys i c o -c he m i c a l a nd b i o log i c a l t r e a t me n t s a r e u s e d t o t e s t t he

na t u re o f t e x t il e e f f lue n t s . The phy s i c a l c ha ra c t e r i s t ic s i nc l ude t e mp e ra t u r e , pH ,

c o l ou r e t c . , w he re a s c he mi c a l c ha ra c t e r i s t i c s i nc l ude t he na t u r e a nd qua n t i t y o f

o rga n i c a nd i no rga n i c c o mp oun ds a nd d i s s o l ve d ga s e s. The b i o l og i c a l c ha ra c t e ri s -

t ic s i nc l ude d i f f e r e n t t ype s o f m i c ro -o rga n i s ms o r m i c robs t ha t a r e p r e s e n t i n t he

e f f lue n t . Th e s e c ha ra c t e r i s t i c s a r e de t e rm i ne d i n t e rms o f B O D ( b i o l og i c a l oxyg e n

d e m a n d ) , C O D ( c h e m i c a l o x y g e n d e m a n d ) , T H O D ( t h e o r e t i c a l o x y g e n d e m a n d )

a nd TO C ( t o t a l o rga n i c c a rbon) e t c .

The to le rance l imi t s ( Indian S tandard Ins t i tu te ) for indus t r i a l e f f luent s , t ex t i l e

indu s t ry raw w as te wa te r charac te r i s t i c s a re g ive n in Table 13 .8 . The to le ranc e l im-

i t s a r e d i f f e r e n t f o r d i f f e r e n t r e c e i v i ng bod i e s . S uc h r e gu l a t i ons a r e i mpos e d t of a c i li t a te fu r t he r pu r i f ic a t i on o f w a t e r by s e w e ra g e a u t ho r i t i e s, w h i c h c a n t he n be

d i s c ha rge d i n t o r i ve r o r o t he r ma j o r w a t e r s ou rc e s . Ta b l e 13 . 9 l i s t s s ome t yp i c a l



C o n s e r v a t i o n o f E n e r g y a n d W a t e r

T A B L E 1 3 . 8

T o le r a n ce L im i t f o r In d u s t ri a l E f f l u en t s [ 31 ]

373

Charac ter i s t ic Tolera nce l imi t , mg/1

A B C D

Su s p en d ed s o l id s 1 00

Dis s o lv ed s o l i d s ( i n o r g an i c ) 2 1 00

p H Va lu e 5 . 5 - 9 .0

T em p er a tu r e , ~ 4 0

Oi l s & Gr ea s es 1 0Tota l r es idua l ch lo r ine 1

A m m o n i a c a l n i t r o g e n ( a s N ) 5 0

T o ta l K je ld ah l n i t r o g en (N ) 1 00

F r ee am m o n ia ( a s N H3 ) 5

B i o c h e m i c a l o x y g e n

d em an d (5 d ay s a t 2 0~ 3 0

C h e m i c a l o x y g e n d e m a n d 2 5 0

Le ad (as Pb) 0 .1

C a d m i u m ( as C d ) 2

H e x a v a l e n t c h r om i u m

(as Cr +6) 0.1

T o ta l ch r o m iu m (a s Cr ) 2

Z in c ( a s Zn ) 5

P e r c e n t s o d i u m , m a x .

R e s i d u a l s o d i u m c a r b o n a t e -

600

2 1 0 0

5 .5-9 .0

45

20

5O

200

2 1 0 0

3 .5-9 .0

10

3 5 0 3 5 0

2 - 1

2 - 2

15 - 15

60 60 -

5

100

5 .5-9 .0

45

20

1

50

100

5

100

2 5 0

1

2

A - E f f lu e n t s d i s c h a r g e d i n to i n la n d s u r fa c e w a t e r s

B - E f f lu e n t s d i s c h a r g e d in t o p u b l ic s e w e r s

C - E f f lu en t s d i s ch a r g ed o n l an d u s ed f o r i r ri g a t i o n

D - E f f lu e n t s d i s c h a r g e d in t o m a r i n e c o a s t al a re a s

ra t ios o f gen era l e f f luen ts . G enera l ly , the tr ea tab i l i ty o f the e f f luen t i s i llus t r a ted by

r a t io o f C OD to BO D. CO D q u an t i f i e s t h e t o ta l o x id i s ab l e p o r t i o n o f t h e e f fl u en t.

B OD i s a m eas u r e o f t h e b io lo g i ca l l y o x id i s ab l e p o r t i o n o f t h e e f fl u en t . T h e h ig h e r

the ra t io o f CO D/B OD , the less tr ea tab le the e f fluen t. The o rgan ic ca rbon i s ox id ised

to CO 2 w h ich i s ex p r es s ed a s T OC [3 3 ]. A s t r en g th an d t r ea t ab i l i ty s im i l a r t o d o -

m es t i c s e w a g e i s t h e o b j ec t iv e .



374 C o n se r v a t i o n o f E n e r g y a n d W a t e r

T A B L E 1 3 . 9

Typ ica l Ra t ios o f Genera l Ef f luen ts [32]Opera t ion Ty p ica l COD/BOD r a tio

Dom est ic sewage 2 .1

Brewing 1 .6

Textiles 1.6-6.0

(average 3 .0)

Ch em ica l m an u f ac tu r e 3 .6

Abattoir 1 .9

1 3 . 8 P o l l u t i o n L o a d s i n P r e - t r e a t m e n t P r o c e s s e s

The na ture o f tex t i le e f f luen ts is very com plex as var ious types o f f ib res and

chem ica ls a re em ploye d in p repar ing the tex t iles . Fur ther the p rocess sequence and

chemica ls employed in the p re- t rea tment p rocesses vary f rom f ib re to f ib re . The

quant i t ies o f po l lu tan ts tha t fo rm the po l lu t ion load go ing in to the waste w ater thus

d ep en d o n th e am o u n t an d k in d s o f f ib re s , t yp e o f m an u f ac tu r in g o p e r a t io n em -

p lo y ed an d W ate r co n su m p t io n p r ac ti ce s .

Approx imate ly 45 mi l l ion tons o f f ib res , o f which over 50% are co t ton , a re

consumed each year fo r tex t i le purposes [33] . Al though syn the t ic f ib res do no t

contain any natural impu ri ties, they produce considerable am ount o f pollutants dur ing

we t p rocess ing . T ab le 13 .10 g ives the charac te r i s t ics o f d i f fe ren t p rocesses wa stes

TABLE 1 3 .1 0

P o l lu t io n Lo ad s o f Co t to n an d W o o l in P r e -t r ea tm e n t P ro cesse s [3 4]

Process W ate r r eq u ir ed BO D COD P o l lu t io n

(1 /k g) (mg 02 / 1 ) (mg O 2 / 1) load (%)

Cotton

Desiz ing

Scour ing

Bleach ing

Mercer iz ing

Wool

Scour ing ( raw wool)

Mil l ing

Carbonis ing

15-20 3000-6000 4000-6000 > 50

4 8000-14000 7000-12000 10-25

150-180 800-1200 80-150 3

7 7-50 10-70 <4

10-40 22000 42600 -

5 -18 4000-24 000 6000-4300 75

30-80 200-500 200-700 1



Co n serv a t io n o f E n erg y a n d W a ter 375

f r om d i f f e r e n t s t a ge s in p r e - t r e a tm e n t o f c o t ton a nd woo l f ib r e/ f ab r i c s . I n c a se o f

c o t ton s i z e s a re the m a jo r f a c to r be ing r e spons ib le f o r a lm os t 7 5% of the po l lu t ionload . In case of woo l , howe ver , the na tura l imp ur i t ie s in the unw ashe d f ibre amo unt

f o r 30 - 50 % of the po l lu t ion load . The a ge n t s u se d in syn the t ic f ib r e s wh ic h a l so

c a use w a te r po l lu t ion a r e l i st e d in Ta b le 13 .11 . The m a te r i a l s wh ic h c a n c a use s ig -

TAB L E 13 .11

C ha r a c te r i s t i c E f f lue n t s f r om Pr oc e ss ing o f S yn the t ic F ib r e s [35 ]

W a t e r c o n s u m p t i o n B . O . D . %

Fibre 1 / kg of f ibre pH p .p .m . Pol lu tant o .w . fVisc ose R a y on 45 7 -9 .5 120 0 - 18 0 0 S u lp hon a te do i l , 2 .0

Antista t ics , 2.0

Dete rgents , 3 .0

NaC1. 10-30

.Aceta te Ra yon 85 7 -9.5 500-800 Sulp hon a ted o i l, 2 .5

Antistatic, 1.5

Detergents , 1.0

Softeners. 2.0

Ny lon 140 - 20 0 7 -9 .5 30 0 - 50 0 S u lpho na te d o i l, 2 - 4

Polya cryl ic s 140-200 1 .5-3 500-700

Polye s te r s 140-200 1 .5-3 300-800

Antistatics, 1.5

Detergents , 1.0

Fatty m atter . 1.0

Form ic ac id , 3 .6

C op pe r su lpha te , 3 .0

Antista t ics , 1.5Dete rgents , 5 .0

Carr iers . 2-10

Antista t ics , 1.5

Dete rgents , 3 .6

Ace t ic ac id , 4 .0

Carr iers . 6-40

n i f i c a n t w a te r po l lu t ion in syn the ti c f ib re we t p r oc e ss ing a r e sp in f in i she s, c on ingoi ls , an t i - s ta t ic agents , synthe t ic de te rgents , s izes , th ickeners e tc . The was te wa te r



376 Co n serv a t io n o f E n erg y a n d W a t er

of synthe t ic f ibres a re h ighly va r iable and a genera l charac te r i sa t ion o f these wa s tes

i s u se f u l on ly a s a n a ppr ox im a te ind ic a t ion o f the i r c onsu m pt ion [36] .1 3 .8 .1 D es i z in g e f f luen t s

S iz ing a g e n t s a nd lub r i c a n t s a r e ne e de d f o r p r odu c ing t e x t i l e m a te r i a ls . S i z e s

used for weav ing can be genera l ly c lass i f ied in to four main c lasses i . e. s ta rch , PVA ,

C M C , a c r y la t e s a nd o the r s . Dur ing the de s i z ing p r oc e ss the y ge t i n to the e f flue n t .

The e f f lue n t i s f u r the r loa de d by the c he m ic a l s ( e nz ym a t i c o r ox ida t ive ) u se d in

de s i z ing a pa r t f r om the s i z e s a nd lub r i c a n t s [37 ]. Ad d i t iona l e f f lue n t l oa ds du r ing

de s i z ing a r e al so p r oduc e d by f ung ic ide s wh ic h a r e m ixe d in w i th the s i z ing a ge n t s

to p r e se r ve the m . S iz e ha s a l so a te nd e nc y to c a use m i lde w, a lga e e tc ., t o f o r m in

pon ds a n d in s low m ov in g s t r e a m s . Thus , t he d i sc ha r ge d e f f lue n t s a c c ou n t f o r a p -

p r o x i m a t e l y 5 0 % o f t h e C O D l ev e l in p r e -t r e a tm e n t p r o c e ss e s . T h e p r o p o r t io n o f

wa te r c ons um e d in th i s p r oc e ss i s c om p a r a t ive ly sm a l l . S ign i f i c a n t c ha r a c te r i s t i c s

o f the e f f lue n t s o f th i s p r oc e s s a r e h igh B OD , h igh TDS a nd som e susp e nde d so l-

id s , wh ic h a r e som e t im e s in c o l lo ida l f o r m . Howe ve r , t he na tu r e o f s i z ing a ge n t

use d de c ide s the B O D o f the w a sh l iquor (Ta b le 13 .12). Na t ive a nd de po lym e r i se d

T A B L E 1 3 . 1 2

O x y g e n D e m a n d o f V ar io u s T y p e s o f S iz e s

B O D s

T y p e o f s iz e m g 0 2 / k g

O x y g e n c o n s u m p t io n

kg 0 2 pe r 10 0 0 kg o f

text i le mate r ia l

C or n s t a r c h 8 10 ,0 0 0 47 7

B r i t i sh gum 6 9 0 ,0 0 0 6 9 0

M ethy l ce l lu lose 1 ,600 1 .6C.M .C. 10 ,000 9 .0

Poly (v inyl) a lcoho l 1 ,600 1 .6

s t a r c he s a s we l l a s e s t e r i fi e d a r e e a s i ly b iode gr a d a b le . B u t o the r p r oduc t s suc h a s

C M C or PVA are not sa t i s fac tor ily degrad ed and a re present a mo re or less pe rs is tan t

form o f po l lu tan t in the upp er layers of was te w a te r (Fig . 13-1) [38, 39 ] . A pos s ib le

so lu t ion to r e duc e the oxy ge n d e m a nd o f s t a rc h s i z e s is the use o f pe r su lph a te to

r e p la c e e nz y m e de gr a da t ion . U nm odi f i e d p o lya c r y la t e s a r e a lso d i ff i c u lt to be de-

g r a de d b io log ic a l ly a nd r e m a in a s po lye le c t r o ly t e s in the a que ous pha se . B y in tr o -




100

8 0 .

/ /

: / 740 -.

20 t / , ~ ~ , - - -- - - : ", -- -- -- x . . . . . .M C

[JL/ ' . C ' - - " " . PVAr . . . . . . ~ . .. .. .. .. .. .. . i { . . ~ _ . t . . . . . . . . . .

5 10 15 20 25 3O

D a y s

F igur e 13 -1 . Oxyg e n de m a nd o f va r ious type s o f si z e s [40] .

duc ing the hydr oph ob ic g r oups , a s a t i s fa c to r y e l im ina t ion f r om the a que ous pha sei s poss ib l e b io log ic a l ly . A no the r a pp r oa c h to m in im ise the po l lu t ion p r ob le m s i s t o

u s e a m i x t u r e o f m o d i f i e d n a t u ra l p o l y m e r s w i t h g o o d b i o d e g r a d a b i l it y a n d s y n -

the t ic po ly m e r w i th e ase o f r e c ove r y a nd re - use . C a t ion ic m od i f i e d p r oduc t a nd

gua r gum s a r e e a s i ly de g r a de d by m ic r oo r ga n i sm s a nd the i r m ix tu r e s w i th su it a b le

starch d er iv ativ es (1 : 4) .

1 3 . 8. 2 S c o u r i n g e f f lu e n t s

The c he m ic a l s u se d in the sc our ing p r oc e ss a r e m a in ly , a lka li e s , we t t ing a ge n t s ,

de t e r ge n t s , s e que s t e r ing a ge n t s e tc . Abou t 2 5 - 40 % of to t a l wa te r u se d in a c om pos -

i te m i l l is c onsu m e d in th i s s e c tion . I n the sc our ing p r oc e ss im pu r i t ie s a re r e m o ve d

f r om the f a b r i c de pe nd ing on the k ind o f f ib r e . Ge ne r a l ly , o i l , c o lou r ing m a t t e r ,

de te rgent , an t i s ta t ic , lubr icants , so lvents , o l igomer e tc . in the presence of a lka l i

cont r ibute to wa te r pol lu tion . S igni f icant charac te r i s tic s o f e f f luents d isch arged f rom

sc our ing se c tion a r e h igh B OD , h igh t e m p e r a tu r e (7 0 -8 0 ~ ve r y h igh pH (10 - 12)

a n d h i g h T D S .

Non- b iode gr a da b le b r a nc he d c ha in a n ion ic su r f a c t a n t s a r e now r e p la c e d by

r e a d i ly b iode gr a da b le s t r a igh t c ha in c om pounds a nd thus po l lu t ion loa d in wa s te



378 C o n s e r v a t i o n o f E n e r g y a n d W a t e r

wa te r i s r e duc e d [41 ] . Non- ion ic e thoxy la t e d a lky l phe no l s wh ic h a r e e x t r e m e ly

use d f o r s c ou r ing a r e d if f ic u l t t o b iode g r a de a t l ow t e m pe r a tu r e. E xc e ss ive f oa m o fthe su r f a c t a n t s m a y se r ious ly a f f e c t t he e f f i c ie nc y o f b io log ic a l w a s te wa te r t r e a t-

m e n t .

C onn ing o i l s , so lve n t s a nd a n t i s t a t i c a ge n t s r e m ove d f r om the f a b r i c du r ing

sc our ing a r e ge ne r a l ly ine r t t o b io log ic a l t r e a tm e n t s [42 , 43 ] . C oa gu la t ion wi th

ca lc ium chlor ide i s use fu l for rem ovin g co nning o i l or a l te rna t ive ly f loa ta tion me thod

c a n be use d .

S c o u r i n g o f w o o l i s m a i n l y d o n e b y d e t e r g e n t a n d s o lv e n t. T h e m a i n c o m p o -

ne n t s o f woo l s c ou r ing wa s te wa te r a re woo l g r e a se , su in t a nd d i r t a nd e xc r e m e n t .

Ta b le 13 .13 show s the po l lu t a n t l oa d o f the woo l s c our ing e f f lue n t . The de te r ge n t

T A B L E 1 3 . 1 3

P o l l u t a n t L o a d o f W o o l S c o u r i n g E f f lu e n t [ 4 4 ]

Pa r a m e te r C o nc e n t r a t ion un i t

C OD 6 0 ,0 0 0 -9 0 ,0 0 0 m g 0 2 / 1

B O D 3 0 , 00 0 - 5 0 ,0 0 0 m g O z 1Pe s t i c ide s a s to t a l o f i nd iv idua l pe s t i c ide s 0 .4 - 1 m g / 1

AO X , a dso r ba b le he log e na te d hyd r oc a r bo n cc~. 1 .0 m g / 1

Ni t r og e n , T o ta l o f a m m onic a l , n i t r a t e a nd n i t r it e N 2 10 0 0 - 150 0 m g / 1

Phos pha te 20 - 30 m g / 1

p r o c e s s i n v o l v e s w a s h i n g o f g r e a sy w o o l w i th h o t w a t e r i n t h e p r es e n c e o f n o n -

ion ic de te r ge n t s a n d sod ium c a r bona te . The c h a r a c te r is t i c s o f t he d i sc ha r ge a r e

ge ne r a l ly a f f e c t e d by bo th the woo l o r ig in a nd the p r e - t r e a tm e n t sys t e m whic h i s

use d to e x t r a c t t he g r e a se a nd wo o l w a xe s . Gr e a se c a u se s b ig p r ob le m s a s it is no t

b iode gr a da b le . I t is poss ib l e to r e duc e the c on c e n t r a t ion o f g r e a se by r e c ove r y , b u t

i t w i l l s t i ll r e m a in h igh f o r b io log ic a l sys t e m s .

1 3 . 8 . 3 B l e a c h i n g e f f l u e n t s

Ge ne r a l ly , t he b l e a c h ing w a s te l i quor in c o t ton p r oc e ss ing i s a lka l ine in na tu r e

w i th B O D 3 .5% of the to ta l l oa d . Hypoc h lo r i t e i s s ti ll u se d a s a b l e a c h ing a ge n t f o r

c o t ton d ue to i ts b l e a c h ing p ow e r a t l ow t e m p e r a tu r e s a nd i ts r e la t ive ly low c os t.

H o w e v e r , t h e f o r m a t io n o f h ig h l y t o x i c c h l o r in a t e d o r g a n ic b y - p r o d u c t s ( A O X )

d u r i n g t h e b l e a c h i n g p r o c e s s h a s l i m i t e d i t s u s e b e c a u s e t h e se t y p e s o f c o m p o u n d s



Co n ser v a t io n o f E n erg y a n d W a ter 379

a r e a po te n t i a l ha z a r d to the d r ink ing wa te r r e sour c e s whe n d i sc ha r ge d [45 , 46 ] .

Ta b le 13 .14 show s the typ ic a l da t a on the to t a l AO X a nd C HC 13 c onc e n t r a t ions in

T A B L E 1 3 . 1 4

A O X a n d CHC13C on c e n t r a t ions in B le a c h in g L iqu id ( p .p .m . )

Tox ic by - p r odu c t s Na OC 1 s t a ge H20 2 s t a ge R inse 1 R inse 2

AO X 105 19 5 2

CHC13 11.5 1.1 0.3 0

spe n t hypoc h lo r i t e b l e a c h ing l iqu ids a nd r in se so lu t ion . C h lo r o f o r m c a n be re duc e d

to v i c tua l ly z e r o by subse que n t pe r ox ide b l e a c h ing a nd ho t wa sh ing . Ge ne r a l ly

b l e a c h i n g w i t h HzO 2 s le ss ha rm ful a s fa r as AOX conten t in the was te wa te r . H202

de c o m pose s in to wa te r a nd o xyg e n a nd l e a ve s l it tl e d is so lve d so l id s o r ob je c t ion -

able res idue b ehind excep t smal l amo unts of sodium s i l ica te and a lka li tha t i s added

to pe r ox id e l i quor . The c om m only use d s t a b i li s e rs l ike DT PA or phos phon a te s a r e

not eas i ly b iodeg radable . A new c lass of sugar ac ry la te comp lex seq ues te r ing agents

a re dev e lop ed for ecolog ica l a l te rna t ive for the presen t range of prod uc ts u sed [47 ].

Pe r a c e t i c a c id i s e nv i r onm e n ta l ly s a f e s inc e i t de c om pose s to a c e t i c a c id a ndoxy ge n [48 , 49 ] . How e ve r , a c e t i c a c id c on t ribu te s s l igh t ly to h ighe r B O D le ve l s o f

wa s te w a te r i n the o r de r o f m a gn i tud e o f 20 - 40 m g B OD/1 . B le a c h ing o f syn the ti c

f ib r e doe s no t c r e a t e a m a jo r wa te r po l lu t ion p r ob le m . I n ca se o f sod ium c h lo r i te

b le a c h ing , t he sod ium n i t r i t e a dde d to the b l e a c h ing ba th c a use s wa te r po l lu t ion .

The sod ium su lph i t e u se d a s a n a n t i c h lo r i s a l so no t de s i r a b le in wa te r . A low

c onc e n t r a t ion o f op t i ca l b r igh te n ing a ge n t do no t c r e at e a ny spe c ia l po l lu t ion p r ob -

l e m , a l thoug h m os t o f the a ge n t s a r e no t b iode gr a da b le w i th in 5 - 10 da ys o f wa s te

wa te r b io log ic a l t r e a tm e n t [50] . In c on t ra s t , howe ve r , som e o f the in t e r m e d ia t e s

use d f o r the p r oduc t ion o f op t ic a l b r igh te n ing a ge n t s a r e m or e o r l es s tox ic .

1 3 .8 .4 Aux i l i a ry e f f luen t s

The c ons um pt ion o f su r fa c t a n t s in t e x t i le we t p r oc e ss ing i s ve r y h igh a nd thus

la rge nu m be r of sur fac tants f ind the i r wa y in to was te w a te r. Text i le aux i l ia r ie s used

in p r e - t r e a tm e n t ha ve r e l a t ive ly lowe r po l lu t ion loa ds . The e thy le ne ox ide /p r opy-

l e ne ox ide c on de nsa te s o f f a tty a lc oho l s a nd a lky l phe no l e thoxy la t e s ( F ig . 13 - 2)

a re m o s t c o m m o n l y u s e d p r o d u c t g r o u p s f o r w e t t i n g /d e t e rg e n c y . H o w e v e r , d u r i n gthe l a s t f e w ye a r s , i t ha s be e n shown tha t du r ing b io log ic a l de g r a da t ion o f a lky l




R •(CH2CH2) H

F ig u r e 1 3 -2 . S t r u c tu r e o f a lk y l p h en o l e th o x y la t e s

p h e n o l e th o x y la t e s , m e tab o l a t e s a r e p r o d u ced w h ich a r e to x i c to f is h es . By ca r e f u l

s e l ec t i o n o f a lk y l p h en o l e th y l en e o x id e i t i s p o s s ib l e t o ach i ev e a d eg r ee o f b io d e -

g r ad ab i l i t y , b u t t h e d eco m p o s i t i o n p r o d u c t s a r e s ti ll p h en o l ic an d t h e r e f o r e t o x i c t o

f i sh . For tunate ly , non- ion ics l ike e thoxyla ted f a t ty a lcohols (F ig . 13-3) , a r e more

R - O ( C H 2 C H 2 ) . ~ H

Figure 13-3 . S t ruc tu re o fe tho xyla ted f a t ty

a lcohol .

d O O - x N a +

F ig u r e 1 3 -4 . S t ru c tu r e o f p o ly a c r y l a t e .

d eg r ad ab l e an d w h o s e m e tab o l i t e s a r e n o n - to x i c . An o th e r e l im in ab l e d i s p e r s in g

ag en t is l o w m o lecu l a r w e ig h t p o ly ac r y l a t e (F ig . 1 3 - 4) . T h e f a t em u l s i f y in g p o w er

o f Lau r y l A lco h o l E th o x y la t e s i s o f im p o r t an ce i n p r e - t r a tm en t o f f ab r ic s a s ch lo -

r i n a t ed p r o d u c t s a r e d i s ch a r g ed . In o r d e r t o r em o v e f a t t y s t a in s , t h e em u l s i f y in g

p o w er h as t o b e h ig h e r t h an 1 0% o f f a t q u an t i ty . Lau r y l Alco h o l E th o x y la t e s h av e

a h i g h e r f o a m i n g t e n d e n c y a n d t h e p r o b l e m s a r e a g g r a v a t e d i n t h e p r e s e n c e o f

s i z i n g p o l y m e r s w h i c h h a v e a f o a m s t a b i l i s i n g e f f e c t . A n i o n i c a l k y l b e n z e n e

s u lp h o n a t e s a r e h a r d co m p o u n d s i n t h e s en s e th a t th ey a r e r e s i s t an t to b r eak d o w n

b y b ac t e r io lo g i ca l ac t i o n in w as t e t r ea tm en t p l an ts . T h e l o w r a t e o f b io d eg r ad ab i l -

i ty is due to the p rese nce o f b ran che d s ide cha in . I f the l inear s ide cha in i s p resen t ,

t h e ra t e o f d eg r ad a t i o n i n c r eas es m ar k ed ly . Ca t io n i c s u r f ac t an t s a r e u s ed in s m a l l

q u an t i t i e s f o r s p ec i a l is ed p u r p o s es . T h es e a r e n eu t r a l is ed o r r en d e r ed n o n - s u r f aceac t i v e b y r eac t io n w i th an io n i c s u b s t an ces w h ich a r e p r e s en t in m o s t e f f l u en ts f r o m

tex t i le works .

1 3 .9 W a s t e W a t e r T r e a t m e n t F r o m P r e - t r e a tm e n t P la n t s

Se lec t i o n o f t h e ap p r o p r i a t e m e th o d o f t r ea tm en t i s i n f lu en ced b y a la r g e n u m -

ber o f f ac t ros r e la ted to each ef f luen t charac ter i s t ic , such as r e la t ive cos t s , l eve ls o f

t r ea tm en t r eq u i r ed o r s i t e r e s t r i c t i o n s e t c . T h e co m p o s i t i o n o f a t ex t i l e e f f l u en t

d ep e n d s n o t o n ly o n t h e t y p e o f m i l l b u t a l s o to a g r ea t ex t en t o n t h e p r o ces s esin v o lv ed . Var io u s m ech an ica l , p h y s i ca l an d ch em ica l m e th o d s can b e u s ed , d e -

p e n d i n g o n th e c o m p o s i t io n o f t h e e ff lu e n t. T h e s e m e t h o d s a r e s u m m e r i s e d i n




Fig . 13 - 5 . B y se ve r a l t e c hn ique s a nd t re a tm e n t s , pa s s ing th r ou gh se ve r a l s t a ge s o f

Phys ic a l C he m ic a l B io log ic a l

S e d im e n ta t ion

Fi l t ra t ion/sc reening

He a t t r e a tm e n t

Dis t i l la t ion

A d s o r p t i o n

Fr e e z ing

Ne u t r a l i s ing

I on- e xc ha nge

Oxida t ion

R e duc t ion

Cata lys is

P h y s i c o - C h e m i c a lCoagulation/flocculation

Ae r a t ion

Act ive ca rbo n f i l t r a tion

Foa m f r a c tiona t ing

Solvent ex t rac t ion

Inc ine ra t ion

O s m o s i s

Elec t ro lys is

Ae r ob ic t r e a tm e n t

Ac t iva te d s ludge

Ana e r ob ic d ige s t ion

Funga l t r e a tm e n t

F igu r e 13 -5 . Phys ic a l , C he m ic a l a nd b io log ic a l t r e a tm e n t s .

pur i f ica t ion , i t i s poss ib le to obta in wa te r suf f ic ient ly c lean to be rec i rcula ted in a

text i le mi l l , a s in o the r sph eres o f indus t ry . Ge nera l ly , the re a re four s tages of e f flu-

e n t t r e a tm e n t s - na m e ly , p r e l im ina r y t r e a tm e n t s , p r im a r y t r e a tm e n t s , s e c onda r y

t r e a tm e n t s a nd t e r t i a r y t re a tm e n t s .

P r e l im ina r y t r e a tm e n t p r oc e sse s r e m ove g r i t a nd so l id m a t t e r s . Th i s inc ludesc r e e n ing , s e d im e n ta t ion , f loa ta t ion a nd f locc u la tion . P r im a r y t r e a tm e n t p r oc e sse s

a re in tended to f i t e f f luents for admiss ion to secondary t rea tments . I t inc ludes

e qua l i s a i ton , p H a d jus tm e n t , ne u t r a l i s a t ion a nd poss s ib l e d i s in f e c t ion . T he se p r e -

l im ina r y a nd p r im a r y t r e a tm e n t s o f the e f f lue n t a re ne c e s sa r y wh e the r the d i sc ha r ge

is to the munic ipa l t r ea tment works or d i rec t to a wa te r course (Fig . 13-6) . The

va r i a t ions in loa d ing a r e e l im ina te d by m ix ing h igh ly c onc e n t r a t e d wa s te w i th ve r y

d i lu t e wa s te i . e . e qua l i s a t ion . Ne u t r a l i s a t ion i s done by a dd ing HzSO 4 or HC1 or

us ing f lue ga se s [52 ] to pH 7 . I f ne u t r a l i s a t ion i s done by us ing HC 1, sod ium

c h lo r ide i s f o r m e d , w h ic h c a nno t be du m p e d in r ive rs due to s a l t bu r de n ing o f r ive r




Industrial . l Pre-/reatment

..

Industrial ~ r ' - ~'---,'-.~.treatment ~ ,, /"

_ _ 7 7

Receivingwaters

Figur e 13 -6 . Wa s te wa te r m a na g e m e n t a c t iv i t ie s [51 ] .

wa te r . I n a dd i t ion the bu i ld ing s t r uc tu r e s a nd p r oduc t ion e qu ipm e n t a r e sub je c t e d

to c o r r os ion by a c id va pour . The H2SO 4 l e a ds to the f o r m a t ion o f su lpha te wh ic h

ha s a dve r se e f f e c t on c onc r e t e . The use o f f lue ga s ha s s e ve r a l a dva n ta ge s ove r

min era l ac ids [53] . F lue gas i s eas i ly ava i lab le f rom boi le r f i r ing ins ta l la t ion . Dur -

ing ne u t r a l i s a t ion b i c a r bona te s a r e f o r m e d wh ic h a re a dva n ta ge ous to the e nv i ron -

men t . A proc ess for the t rea tmen t of e ff luents us in g f lue gas i s show n in Fig . 13-7 .

Wateror ~ ,waste water ~~ -~ .

sc , b, U

~ Boiler lues

A lk al i n e ~ . 3 o h,otog,~,lwaste w a t e r ~ c ~ ' ~,,

Figure 13-7 . Process f low diagram for neut ra l i sa t ion of f lue gas .

The se c onda r y t r e a tm e n t m e thod s a r e u se d to r e duc e the o r ga n ic loa d o f t e x t il e

e f f lue n t s . I t c ons i s t s o f a e ra t ion , c he m ic a l c oa g u la t ion a nd b iode gr a da t ion . Ae r a -

t ion he lps in r e duc ing the poss ib i l i t y o f odour f o r m a t ion a nd s ludge p r oduc t ion .

Ef f luent conta ins impur i t ie s in d isso lved , co l lo ida l and suspended form. Prec ip i ta -

t ion a nd c oa g u la t ion o f the se im pu r i ti e s to p r oduc e m ic r o f loc s i s done e i the r by pHadju s tm ent ( such as ac id c racking) , or by inorganic coagu lants (mu l t iva lent meta ls )




o r b y o rg an i c co ag u l an t s . A c ry l ic ac i d b as e s i ze can b e co m p l e t e l y r em o v e d f ro m

ef f l u en t b y p rec i p i t a ti o n . C o m m o n l y u s ed co ag u l an t s a r e li me , f e r r ic s u l p h a te , f e r-r i c ch lor ide , fe r r i c a lum, ca lc ium ch lor ide , a lum in ium su lphate , su lphur ic ac id e tc .

O rg an i c co ag u l an t s a r e lo w m o l ecu l a r mas s , h i g h l y ch a rg ed p o l y e l ec t ro l y t e s t h a t

a re usua l ly c a t ion ic , and can be used e i ther as an a l t e rna t ive to , o r in con jun ct ion

wi th , inorgan ic coagulant s . Thei r me chan ism can be exp la ined in te rms of the charged

p a t ch m o d e l (F ig . 1 3 -8 ). W h en t h e imp u r i t ie s i n th e w as t e w a t e r a r e i n th e fo rm o f

" ~ ~ ~ Ads~176 t~' "~-' "A ~ . '

as patch 9 . ~ "

% . / - - . ' - 3 , . - J --)..1 Elecu'ostaticattm'action rings

particlesogether

~s~on

F i g u re 1 3 -8 . T h e ' ch a rg e p a t ch ' co ag u l a t io n mo d e l .

m i c ro f l o cs an d o t h e r s u s p en d ed s o li d s, t h e s eco n d s tag e o f f l o ccu l a ti o n ag g reg a t e s

them in to l a rger agg lom era tes . F loccu la t ion invo lves adsorp t ion o f the po lye lec t ro -

ly te on to par t i c le su r faces . These fo rm loop s and t a il s w hich ac t as phys ica l b r idges

ac ro s s t h e p a r ti c l e s , th u s b i n d i n g t h e m t o g e t h e r i n to a p o l y m er -p a r t i c l e m a t r i x o r

f loc i .e . a b r idg ing mechan ism (F ig . 13-9) . A subs tan t i a l p ropor t ion o f co l lo ida l

Adsorptionandbridging

t . ; Ol l l l i l e l l c e

Adsorption ndflcculatio.........._.._._~n..

' complete

I Adsorption ontinuesbridges horten nd,multiply

F i g u re 1 3 -9 . T h e ' b r i d g i n g ' f l o ccu l a ti o n mo d e l .



384 Conservat ion o f Energy and Water

dir t ( s tab i l i sed by de te rgen t) f rom w ool scour ing e f f luen t can be rem ove d by f loc-

cu la t ion p rocess (F ig . 13-10) wi th h igh mo lecu lar mass b r idg ing f loccu lan t l ike

[ ' ~ S c o u t bo w l ]Polymer C - . . . . . - - ~ _ _ _ . _ . _ . _ _ _ i

t a n k ~ _ ) [ " ~ ' - - ' -- 7 - - - - - - _ . . - - 1 _ . _ . . ,

- [ ] S ~m g m , . w - - - - - - - ~ o r

.......... r

, o , , . . , .

Figure 13-10 . F low d iagram of a typ ica l wo ol- scour t rea tme nt p lan t .

po ly e lec t ro ly te wi th s l igh t an ion ic o r ca t ion ic charge de pending on the par t icu la r

charac te r i s t ics o f the l iquor to be t rea ted . R ecyc l ing o f the l iquor to the sco ur ing

bow ls is a lso possible . C onv entiona l centr ifugation, f loatat ion or set t ling is broa dly

used fo r g rease and suspend ed so l id rem ova l f rom wool scour ing waste water . Hot

acid cracking also increases grease rem oval . G rease rem oval before biological t reat-

m ent w i l l g rea t ly increase the load removal . Typica~ reduc t ions in suspend ed so l ids

(and the ac com pan ying reduc t ion in COD) are shown in Tab le 13 .15 . Grease re -

T A B L E 1 3 . 1 5

Ty p ica l Da ta f r o m T r ea tm en t o f Wo o l Sco u r E f flu en t

Trea tmentCOD SS

(rag/l) R edu ction (%) (rag/l) Red u c t io n ( %)

Untrea ted 100490

Cen tr ifuga t ion 91500 960 m g/1 Z e tag 92

Cen tr ifuga t ion 60460 40

100 rag/1 Z etag 92

Cen tr ifuga t ion 50650 50

30950

26200 15

19370 37

13400 57

cove ry by cen t r i fuga t ion i s usua l ly less than 50%. A nother sys tem of wool scour -

ing waste w ater t rea tme nt i s by land i r rega t ion [54]. The t rea tm ent s teps a re , s to r -

age and aerob ic d iges t ion by s ta tic aera t ion , land fa rming and eva pot ransp i ra t ionof land fa rm ing leacha te .

In b iodegrad a t ion , the micro-o rgan ism s a re u t i li sed to degrade the o rgan ic ma-




te r ia l s i n t h e w as t e s t r eam . Ae r o b i c b ac t e r i a r eq u i r e s o x y g en w h i l e an e r o b i c b ac t e -

r ia t h ri v e i n th e a b s e n c e o f o x y g e n . M i c r o b e s c o n s u m e s o r g a n i c m a t t e r g i v i n g o u t

f in a l l y g as eo u s p ro d u c t s . T h e m o s t co m m o n ae r o b ic b io lo g i ca l t r ea tm en t p r o ces s es

are ac t iva ted , t r i ck l ing f i l t e r s [55] . A schemat ic f low char t fo r ac t iva ted s ludge

t r ea tm en t i s s h o w n in F ig . 1 3 - 1 1 . T h e ac t i v a t ed s lu d g e p r o ces s i n v o lv es m ix in g o fActivated ludge ecirculation

I I § Effluent ecirculation .. .!

! - _ ?

C ~ Effluent

Solidsdisposal SludgeA-Preliminary reatment C-Aeration ank disposalB-Primary reatment D-Secondm'y ettling

F ig u r e 1 3 - 11 . Ac t iv a t ed s lu d g e p l an t .

i n c o m i n g w a s t e w a t e r w i t h b i o l o g i c a ll y a c t iv e s l u d g e o r s u s p e n s i o n s o f m i c r o -

o r g an i s m s . T h e m ix tu r e i s t h en ae r a t ed w i th co m p r es s ed a i r o r m ech an ica l ae r a to r s

f o r t h e d es i r ed l en g th o f t im e b e f o r e t r an s f e r r i n g t h e s am e in to an o th e r t an k w h er e

th e ae r a t ed s lu d g e i s s ep e r a t ed b y s ed im en ta t i o n . T h e t r ea t ed e f f l u en t i s t h en d i s -

ch a r g ed t o th e n a tu r a l s t ream s . B io lo g i ca l s y s t em s a s ac t i v a t ed s lu d g e an d ae r o b i c

f i l t e r s h av e b een w id e ly u s ed t o ach i ev e s t r i c t s t an d a r d s i n w o o l s co u r in g w as t e

w a te r t r ea tm en t s . T h e r em o v a l o f s i z in g ag en t b y ae r o b i c b io d eg r ad a t i o n i s r e -

s t r ic ted a lmo s t en t i r e ly to na tu ra l p rod ucts l ike s ta rch . The s ta rch i s usu a l ly dec om -

p o s ed b y b ac t e r i a w i th t h e a id o f s p ec i f i c en zy m es i n to i t s f u n d am en ta l b u i l d in g

b lo ck s i .e . w a t e r , C O 2 an d N H 3. Co n s id e r ab l e am o u n t o f b io m as s i .e . s l u d g e , a r e

t h u s p r o d u c e d a n d m u s t b e d i s p o s e d o f.T e r t i a r y t r ea tm en t p r o ce s s es a r e u s ed o n ly t o e l im in a t e m a te r i a l s w h ic h a r e n o t

a m e n a b l e t o s e c o n d a r y t r e a tm e n t . A t r e a tm e n t m e t h o d f o r w o o l s c o u r i n g e f fl u e n t

h a s b e e n d e v e l o p e d , c o n s i s ti n g o f e v a p o r a t i o n a n d i n c i n e r a t io n p l a n t i n c o m b i n a -

t i o n w i th a b io lo g i ca l p l an t [ 5 6 ] . T h e r e s u l t i n g co n d en s a t e s f r o m th e ev ap o r a t i o n

p l an t an d t h e i n c in e r a t i o n r e s id u es a r e r ecy c l ed s o t h a t t h e w a te r , am m o n ia an d

s co u r in g a id s a r e r e tu r n ed t o th e p r o d u c t io n p l an t [ 57 ].

O r g a n i c r e m o v a l p r o c e s s e s a r e a c h i e v e d b y a d s o r p t i o n , f o a m s e p e r a t i o n a n d

ch em ica l o x id a t i o n . In ad s o r p t i o n a c t i v a t ed ca r b o n , s i l i c a g e l , ch i t o s an f ib r e , f u ll -

e r s ea r th e t c . a r e u s ed t o ab s o r b im p u r i t i e s f r o m w as t e w a te r . T h e s i ze s f r o m th e



38 6 C ons e r va t i on o f Ene r gy and Wate r

tex t i le e f fluents can be remo ved by b io e l imin a t ion i .e . adsorpt ion by s ludge . Acryl ic

a c id a nd po lya c r y la t e s i z e s c a n be r e a d i ly d i spose d o f by a dso r p t ion by the s ludge .

C M C c a n n o t b e e l i m i n a t e d i n w a t e r t r e a tm e n t p l a n t s, w h e t h e r b y b i o d e g r a d a t i o n ,

a dso r p t ion o n the s ludge o r p r e c ip i t a tion . F oa m se pe r a t ion tr e a tm e n t invo lve s the

pa ss in g o f c om pr e sse d a i r t h r ough the wa s te wa te r c on ta in ing su r f a c e a c t ive a ge n t s

a nd the f oa m r i c h in su r f a c t a n t i s s e pe r a t e d . C he m ic a l ox ida t ion i s u se d f o r de -

c r e a s in g t h e B O D . O z o n e , H202, man ganese pe r c h lo r a t e a r e ge n e r a l ly u se d f o r th i s

pu r pose .

I no r ga n ic r e m ova l p r oc e sse s a r e a c h ie ve d by a ne r ob ic de n i t ri fi c a tion , a lga e ha r -

ve s t ing , e l e c t r od ia lys i s , i on - e xc ha nge r e s ins , so lve n t e x t r a c t ion e t c. The e l e c t ro -

c he m ic a l t e c hno logy i s ve r y e f f e c tive in the r e duc t ion o f c o lou r. O z one t r e a tm e n t i s

a l so a pp l i e d p r im a r i ly f o r d i sc o lou r a t ion , bu t i t c a n a l so im pr ove the qua l i ty o f

e f f lu e n t i n m a n y o t h e r w a y s . G a m m a r a d i a t io n - i n d u c e d o x i d a t io n a p p e a r s to b e

e f f e c t ive in d i sc o lou r ing r e f r a c to r y dye s . F r e e z ing , a m m onia s t r ipp ing , d i s t i l la t ion

a r e a lso e m ploy e d to r e m ove im p ur i t ie s f r om e f f lue n ts .

Th e r e c ove r y o f c a us ti c f rom the m e r c e r i z a t ion p r oc e ss i s a c om m on p r a c t i c e in

the t e x t il e i ndus t r y . M e r c e r i z e r r in se wa te r i s no r m a l ly r e c ove r e d w he n i ts c onc e n-t r a t ion i s a bove 2 - 3% a nd be low th i s c onc e n t r a t ion i t is d i sc ha r ge d to w a s te t r ea t -

m e n t . An a l t e r na tive to th is p r oc e d ur e i s t o u se a n u l tr a f il t ra t ion m e m br a n e to f il te r

c a us t i c rin se w a te r be f o r e the so lu t ion g oe s to the e va por a to r . A f low she e t d i a g r a m

of c a us t ic r e c ove r y so lu t ion is show n in F ig . 13 -12 . The c l a r if i e d a nd c onc e n t r a t e d

so lu t ion i s t he n r e a dy f o r r e - use a nd c onsum pt ion o f c a us t i c i s s ign i f i c a n t ly de -

c reased [59 ] .

The r e c ov e r y o f s i z ing a ge n t s by m e a ns o f u l t r a f il t r a tion h a s be c om e ve r y popu-

l a r a s a r e su l t o f e nv i r onm e n ta l l e g i s l a t ion [59 - 6 1 ] . The r e c ove r y o f c he m ic a l s ,

e n e r g y a n d w a t e r fo r r e u s e is m o r e e c o n i m i c a l to d a y . R e c o v e r y o f P V A w a s o n e o f

the f i r st r e c yc le p r o c e sse s to be use d by t e x t i l e i ndus t r y [62 ] . A d ia g r a m o f PVA

r e c ov e r y sys t e m i s shown in F ig . 13 - 13 . An im por t a n t f a c to r is t ha t whe n s i ze i s

r e c ove r e d , 6 0 ,0 0 0 ga l lons o f d i sc ha r ge f r om e a c h r a nge pe r da y is e l im ina te d f r om

the wa s te s t re a m .

Hy pe r f i l t r a t ion o r r e ve r se osm os i s i s a s e pe r a tion p r oc e ss invo lv ing the f i lt r a-

t io n o f a q u e o u s s o l u ti o n s b y m e m b r a n e s c a p a b l e o f r e m o v i n g n o t o n l y s u s p e n d e dpa r t i c l e s bu t a l so subs ta n t i a l f r a c t ions o f d i s so lve d im pur i t i e s , i nc lud ing o r ga n ic




TO E V ~ R A T ~ I0 0 GPI'I,

NiOH 13~40GP~

~0 ~ NaOH F rom Evap o r i to r 30~ NaOH F r o m E v a p o r a t o r

T

w r , ~ . i I , , I w ~ , E R

sco u r ,1,. .72.='~.. . . I c . u s n c ] _ 3 - . s Na o ,OVERFLOW[ T i ~ i ~ i r ~ l [OVERFLOW ~ a-~m Nma~

. . o . t - . . l , i W~ ' i . J ' ' ' T ''~ ~. . . . . . . . ] 3 0 - 5 0 GPl-I

NG [ '~" . . . . . . . - T TO SV~O R^TO ~ --R A E i V .

~ E ~ ~ ~ ~ . ~ . . . . . . . . . . . . . .

1 ~ ; ~ . I r . ~ , ~ , i - . - - - ~

. . . . . ' , " - - ; ;2 x, , , : > o o < < ,4~no~ u~tS ~ I~ I EeO I n I i lull iT - , I . . ' ~ , I ,.r [ 7HO G~ i ~ ~ 1 UNIT el

Figure 13-12 . Caus t i c recovery sys tem [58] .

. . , , , r I L . . E .

. .. .. . < ' ~ . . ~ - , ;~ E , ~ ~ l' I t j ..................: . . . . . . . . . .

F i g u re 1 3 -1 3 . P V A rec o v e ry s y s t em [ 63 ] .

an d i n o rg an i c m a t e r i a l. T h e u s e o f r ev e r s e o s m o s i s a l on e o r in co m b i n a t i o n w i th

o t h e r t r ea t me n t i s s u g g es t ed fo r r eco v e ry o f s ize s [ 64 -66 ] . In t h is me t h o d , w a t e r

an d s o l u b l e s a l t s a r e s e l ec t i v e l y r emo v ed f ro m t h e d es i z i n g l i q u o r b y p as s i n g i t

t h ro u g h u l t ra f i l tr a t i o n mem b ran e . T h i s i s a s y s tem fo r m ak i n g s i z in g ag en t s mo re

co n ce n t r a t ed an d r ec y c l e t h e r ec l a i med l iq u o r i n a co n t in u o u s cy c l e d u r i n g s i z i n g

an d w eav i n g . F i g . 1 3 -1 4 s h o w s a s i mp l i fi ed li n e d iag ram o f a s y s t em o f m ak i n gs i z in g ag en t s mo re co n cen t r a t ed . W i t h u lt r a fi lt r a ti o n , t h e m em b ran es , w h i ch ma y




<

. . . , . . . , . , . , . - . . . . . . , . . . . . . - . .

9 . - . . . . . . . . . . . . . . . - . . , . . . , . .- . . . . .

9 . - . . . . . . . . . . . . - . . . . . . , . . . . .. . . . .

. . - . . . - . , . - . . . . . . . - . , . . . . . . . . . - . . . - .

. . . . . . . . . . . . . . . . - . . . . . . . . . . . . . . . - . . .

. . . . . . . . . . . . . . . - . - . . . . . . . . . . , , . . . .

Pe r m e a te to the sc our ing l iquor

U

?

F R e c l a i m e dl iquor

Figure 13-14. Inc reas ing the concent ra t ion of s iz ing agent [66 ] .

e i the r be in the shape o f tube or co i l, r e ta in the remo ved subs tance s f rom a ce r ta in

m ole c u le s i z e onwa r ds . Te c hn ic a l de t a i l s on u l t r a f i l t r a t ion i s p r e se n te d in Ta b le

13.16. An averag e pe rm ea t io n ra te of 20-25 1 /m2h is a t ta ined in inc reas ing the con-

T A B L E 1 3 . 1 6

R e c yc l ing S iz e s by U l t ra f i l tr a t ion [6 7] .

Ini t ia l con cen tra t ion (%) 1.5

Fina l conce nt ra t ion (%) 8 .1

P e r m e a t i o n r a t e

Initial (1/m2h) 13 0-15 0

Fin al (1/m2h) 8-10

Av erag e (1/m2h) 20-25

Reten t iv i ty (%) 95

Tem pera ture (~ 80

c e n t r a t ion o f a c r y l ic a c id ba se s i ze in wa sh ing l iquors to a va lue o f a bou t 9 %. W i th

ul t ra f i l t r a t ion the s ize conta in ing scour ing l iquor i s c i rcula ted unt i l the cyc le l iquor

reaches a des i red concen t ra t ion [68] . The regen era ted s ize i s r eused pe r se or m ixed

wi th o r ig ina l p r od uc t ( 10 - 20 %) . R e c ove r y r a t e s o f 7 0- 8 5% in r e c yc l ing PV A s i ze s

ha ve be e n r e por t e d [69 ] .

The r e c o ve r y a nd r euse o f s i ze m ix tu r e s c on ta in ing CMC, PVA, po lya c r y la t e s

a re s tudied by u l t ra f i l t r a t ion technique [70] . F ig . 13-15 shows the extent to whichd i f f e r e n t g r oups o f s i zing a ge n t s c a n be r e c yc le d . T he in f lue nc e e x te nde d by the



Conse rva t i on o f Ene rgy and Water 389

Increasingly necessary

because o f environmenta l

legislation

R e c y c l i n gm a t e r i a l s

Modi f i ed " ' \/ starch, \

/ biological ,~,, therm al & f

\ mechanical /

~de_composition/

Starch bio/ ~'\, ,,/ therm/ ~

\ mechanica l / /~ c o m p o s i t i o n /

/ ' , \

" \ \ \

" \ \

l a c to m a n n a n ?9 / /\ /

\ / / /\ \ /

Figure 13-15. Re cycl ibi l i ty of various grou ps o f s iz ing agen ts [66].

sal ts co m m on ly u sed (part icularly Ca 2+ ions), the therm al , m echan ical and biolog i-

cal s tabi l i ty and the el im inabi l i ty o f these size mixtures are invest igated [71 ] . I t i s

found tha t s ize mixtures conta ining polyacryla te show marked advantages over

mixtures of CMC and PVA. I t i s c la imed tha t yams s ized wi th recyc led l iquor

performed bet ter during weaving than warp sized with the original l iquor. This is

because the shor t cha in molecules a re removed f rom the par t icula r s iz ing agentdur ing ul t ra f il t ra t ion. These a re found aga in in the permeate . The imp rovem ent i s

the resul t of the s ize becoming more uni form. Modem techniques for recyc l ing

sizing agents are one w ay o f redu cing effluent loads in the text ile industry. Bu t the

m ain diff icul ty is , the com m ission finisher has no reliable inform ations conce rning

the size con tent of the grey fabrics he has to f inish [72 , 73] .

Every effluent t reatment plant wil l produce sol id waste , which has to be dis-

posed off proper ly , as i t conta ins hazardous chemica ls . Som e of these m ater ia l s a re

highly toxic , others are corrosive, f lammable, i rr i tants , explosive, infect ious e tc .

Disposa l o f these sol id was tes a lway s presents a problem. W aste di sposa l sys tems



3 9 0 C o n s e r v a t i o n o f E n e r g y a n d W a t e r

c o m m o n l y p r a c t i s e d a r e l a n d f i l l e i t h e r o n s i t e o r t o m u n i c i p a l o p e r a t i o n , i n c i n e r a -

t i o n , o c e a n d a m p i n g , sp r a y i r re g a t i o n o r h a u l i n g t o m u n i c i p a l t r e a t m e n t p l a n t. M o s to f th e c o u n t r ie s h a v e a p p r o v e d l a n d fi ll s f o r v a ri o u s t y p e s o f w a s t e s w i t h p r o p e r

p r e c a u t i o n s . T h e i n c i n e r a t io n o f t e x ti le w a s t e is n o t u s u a l ly r e c o m m e n d e d d u e t o

a i r p o l l u t i o n a n d t h e a s h w h i c h h a s h i g h c o n c e n t r a t io n o f h e a v y m e t a l s .

1 3 . 1 0 P r o t e c t i v e M e a s u r e s f o r U l t r a v i o l e t R a d i a t i o n

T h e p r o b l e m s o f o z o n e d e p l e t i o n in th e u p p e r a t m o s p h e r e h a v e l e d to i n c r e as e d

p r o b l e m s o f e x p o su r e o f t h e sk i n t o so la r u l tr a v i o l e t r a d i a t i o n [ 74 ]. U l t r a v i o l e t

r a d i a t i o n t o e a rt h , d u e to th e a b o v e e f f e c t c o u l d g r a d u a l l y a ff e c t h u m a n ' s i m m u n e

sy s t e m . A i l m e n t s l i k e c a t a r a c t , l u n g d i s e a se s a n d sk i n c a n c e r wo u l d i n c r e a se . A p -

p r o x i m a t e l y 9 0 % o f n o n - m e l a n o m a a n d 6 5 % o f m e l a n o m a s k in c a n ce r s h a v e b e e n

a t t r i b u t e d t o u l t r a v i o l e t e x p o su r e .

T h e U V R b a n d h a s b e e n i d e n ti f ie d a s c o n s i st i n g o f t h re e r eg i o n s , n a m e l y , U V A

f r o m 3 2 0 n m t o 4 0 0 r im , U V B r e g i o n f r o m 2 9 0 n m t o 3 2 0 n m a n d U V C f r o m 2 0 0

n m t o 2 9 0 n m . T h e r e g i o n s o f u t m o s t c o n c e r n f o r s k i n c an c e r a r e t h e U V B a n d

U V A r e g i o n s [ 75 ]. U V C , U V B a n d U V A r a d it io n a r e u s u a l ly a b s o r b e d b y t h e o zo n e

l a y e r, w i t h n o U V C a n d o n l y h a l f o f t h e U V B r e a c h i n g t h e s u r f ac e o f t h e e a rt h . T h es i z e a n d d e p t h o f t h e A n t a r c t i c o z o n e h o l e h a s c a u se d c o n c e r n p a r t i c u l a r l y i n A u s -

t r a li a , wh e r e i t h a s b e e n su g g e s t e d t h a t a d e c r e a se o f 1 % in o z o n e w o u l d l e a d t o

i n c r e a se i n th e u l t r a v i o l e t r a d i a ti o n a t t h e e a r t h ' s su rf a c e a n d m a y e v e n t u a l l y l e a d t o

a 2 - 3 % i n c r e a se i n sk i n c a n c e r [ 76 ] .

P r o t e c t i o n f r o m U V R i s a v a i l a b l e t h r o u g h t h e u s e o f s u n s c e e n s a n d c l o t h i n g .

S u n s c r e e n l o t i o n s c o n t a i n U V R a b s o r b e r s a n d s u n b l o c k e r s c o n t a i n p i g m e n t t h a t

p h y s i c a l l y b l o c k s U V R . H a t s, s u n s c r e e n s , s u n g l a s s e s a n d c l o th i n g c a n b e u s e d to

d e c r e a se t h e e x p o su r e t o u l tr a v i o l e t r a d i a t i o n b y a f a c t o r o f 1 0 o r m o r e , a s we l l a s

b y p e o p l e a v o i d i n g e x p o s u r e t o th e s u n a t i ts m a x i m u m [ 74 ] .

T h i s o p e n s u p a n o t h e r a r e a o f o p p o r t u n i t y f o r te x t il e f a b ri c a n d g a r m e n t p r o -

d u c e r s t o m a n u f a c t u r e c o m f o r t a b l e r a n g e s o f c l o t h in g f o r l e is u r e a n d f o r o u t d o o r

w o r k w e a r t h a t o ff e r s i g n i fi c a n t e n h a n c e d p r o t e c t io n a g a i n s t u l tr a v i o l e t r a d i a ti o n .

T h e a p p r o p r i a t e s e l e c ti o n o f d y e s, f l u o r e s c e n t b r i g h t e n i n g a g e n t s, a n d p a r t i c u l a r l y

U V R a b so r b e r s sh o u l d e n a b l e c o t t o n f i n i sh e r s to p r o v i d e t h e h i g h l e v e l s o f p r o t e c -

t io n d e m a n d e d [ 77 , 7 8] . T h e i m p o r t a n c e o f a s s e s s in g t h e p r o t e c ti o n a f f o r d e d b ya p p a r e l f a b r ic s i s r e c o g n i s e d a n d t h e re i s m u c h r e s e a r c h b e i n g c o n d u c t e d o n t h e




m an n er i n w h ich d i f f e r en t f ib r e s , f ab ri c s , fab r i c co n s t r u c t io n , co lo r an t s , ad d i t i v es ,

e t c. i n f l u en ce t h e UV p r o t ec t i o n o f tex t i l e s [79 - 82 ] . T h e co v e r f ac to r o f a fab r ic

( t h e p e r cen t o f o p en s p aces t o c lo s ed s p aces ) h as b een i d en t i f i ed a s an im p o r t an t

d e t e r m i n a n t i n p r o t e c t iv e n e s s a g a i n s t U V R t r a n s m i s s i o n a n d S P F ( su n p r o t e c ti v e

f ac to r ) [ 83 ] . Su n p r o t ec t i o n f ac to r (SP F ) o f f ab r i c s i s im p r o v ed b y ap p ly in g UV

abso rber s to f abr ics [81 ] . W ov en fabr ics usua l ly have h igh er cove r f ac to r s than kn i t

d u e t o t h e y a r n s i n w o v en f ab r i c s l y in g c lo s e ly t o g e th e r an d m in im i s in g s p aces

b e t w e e n t h e y a m s a n d t h u s th e a p p l i c a ti o n o f a r e a c t iv e U V a b s o r b e r p e r f o rm a n c e

d ep e n d s o n th e f ab r ic [84] . P a le s h ad ed f ab r i c s o f co t t o n , s il k , p o ly a m id e s h o w

l it tl e p r o t ec t io n ag a in s t i n t en s e UV r ad ia t io n . T h e d a r k e r s h ad e o f an y co lo u r s h o w s

h ig h e r p r o t ec t i o n p r o v id ed f r o m s u n b u r n [80 ] .

T w o ad d i t i o n a l co n s id e r a t i o n s i n ev a lu a t i n g t ex t i l e s a s p r o t ec t i o n f r o m UVR

ar e w e t t i n g an d s t r e t ch in g . I t i s s h o w n th a t th e S P F o f fab r i c s i s r ed u c ed w h en th e

fabr ics are wet [84, 85] . A de crease in SPF values o f fabr ics as a func t ion o f s t retching

of f abr ics i s observed [85 , 86] .

SP F i s t h e r a ti o o f t h e l en g th o f t im e o f s o la r r ad i a t i o n e x p o s u r e r eq u i r ed f o r t h e

s k in t o s h o w r ed n e s s ( e r y th em a) w i th an d w i th o u t p r o t ec ti o n . T h e t e r m SP F o r UP F(u l t r av io l e t p r o t ec t i o n f ac to r ) h as b een i n t r o d u ced s u ch t h a t a g a r m e n t o f UP F 1 5

w i l l p r o v id e t h e s am e am o u n t o f p r o t ec t i o n ag a in s t s o l a r u l t r av io l e t rad i a t i o n a s a

s u n s c r ee n o f SP F 1 5. Ga r m e n t s w i th a UP F v a lu e o f 2 0 - 2 9 o f f e r h ig h p r o t ec t i o n

( U V R t r a n s m i s s i o n 5 . 0 -3 . 3 % ) . A U P F v a l u e o f 3 0 -4 0 ( U V R t r a n s m i s s i o n 3 .3 -

2 . 5 % ) o f f e rs v e r y h ig h p r o t ec t i o n an d a UP F v a lu e o f 4 0 + o ff e r s m ax im u m p r o t ec -

t io n w i t h a U V R t r a n s m i s s i o n o f 2 . 5 % .

T h e p r o t ec t i v e n es s t h a t f ab ri c s an d g a r m e n t s can a f f o rd ag a in s t UV R i s o f g r ea t

im p o r t an ce t o co n s u m er t h r o u g h o u t t h e w o r ld an d a s y s t em a t i c r e s ea r ch is y e t t o b e

p e r f o r m ed o n each o f t h e v a r iab l e s t h a t h as b een i d en t i fi ed a s im p ac t in g o n SP F o f

fabr ics .

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33 Ha rald Du nser, Th e Indian Tex t i le J ., 102 (4) (1992) 80.34 S. Du rig. , Rev. Prog. Color. , 7 (1976) 70.



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47 H. Bac hus , Tex t i lvered lung , 30 (1995) 152.

48 R. C. Be tr i l le , AA TC C Int . Con f . B ook of pape rs, 1993, p 205 & 214.

49 P. W fii'ster, Te xtil Praxis, 47 (1992 ) 960.50 R. Anilker , Rev. Prog. C olor and Rel . Topics, 8 (1977) 60.

51 P. I . N orm an and R. Seddo n, J. Soc. Dy ers Colou rists , 107 (1991) 216.

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54 N. Atharasop oulous , M el l iand Tex t i lber ich te , 73 (4) (1992) E 167.

55 R. P. M athew , Amer . Dy estu f fR ep . , 63 (8) (1974) 19.

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57 R. H. Ho ffm an and G. T im m er , M el l iand Tex t i lber ich te , 72 (1991) 562 .

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61 L. S . M e y e r - Sto rk , M el l iand Tex t i lber ich te , 75 (1994) 828.

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3 94 C onse r va t i on o f Ene r gy and W ate r

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86 R. M. Sa yre and S. N. G. Hu ghe s , S kin Canc er J. , 8 (1993) 41.



Chapter 14

P R E - T R E A T M E N T O F T E X T I L E S U N D E R P L A S M A C O N D I T I O N S

1 4 . 1 I n t r o d u c t i o nTo - da t e , the r e qu i r e d su r f ac e m od i f i c a t ion o f the f ib re i s m a in ly a c c om pl i she d

by we t c he m ic a l p r oc e s se s . An a ppr opr i a t e a l t e rna t ive to it s c onve n t iona l t e c h -

n ique s i s g ive n by the p r e - t r e a tm e n t o f t e x t il e f ib re s w i th low t e m pe r a tu r e g low-

disch arge p la sm a in a i r [1-10] . The re i s a lso an inc rease in pa tent ap pl ica t ions on

the l a t e st de ve lopm e n t s in p l a sm a t e c hno logy [ 11 - 14 ] . Phys ic o - c he m ic a l m e thod

of m od i f y ing the su r f a c e o f po ly m e r subs t r a t e s w i thou t c ha ng ing the na tu r e o f the

bu lk o f the sub s t ra te has been of grea t in te res t . Pa r t icu la r ly in the a rea of pre -

t rea tm ent o f tex t i le s , th is techno logy w hich i s r e la t ive ly new to the tex t i le indus t ry ,

se e m s to b r ing a bou t obv ious a d va n ta ge s in r e l a tion to the c onve n t iona l t e c hn ique .

The r e a son f o r th i s i n t e r es t i s t he in t r igu ing poss ib i li t y o f m od i f y in g p o lym e r s a nd

ob ta in ing n e w a nd in t e r e s t ing p r ope r t ie s l e a d ing to be t t e r pe r f o r m a n c e .

C on ve n t iona l w e t p r e - t r e a tm e n t p r oc e sse s o f t e x t il e s a re ge ne r a l ly e ne r gy c on-

sum ing p r oc e ss . P la sm a m od i f i c a t ion o f t e x t il e s sa ve s la r ge qua n t i ty o f wa te r ,

c he m ic a l s , a nd e le c t ri c a l e ne rgy . Ec o log ic a l a nd e c onom ic a l c ons t r a in t s w h ic h a r e

im po se d on the t e x ti l e i ndus t r y to an inc r e a s ing e x te n t , c al l f o r t he de ve lopm e n t o fenv i ronm enta l ly f r iendly and econ om ic f in ish ing processes . Large savings a re pos-

s ibl e s inc e the p l a sm a p r oc e ss doe s no t p r oduc e l a r ge vo lum e s o f wa s te o r t ox ic by -

produc ts [9 ] .

1 4.2 T h e C o n c e p t o f p la s m a

Plasm a is kn ow n as the four th s ta te of the mat te r . P lasm a is pa r t ia l ly ion ised

gases , cons is t ing o f ions , e lec t rons and neut ra l pa r t ic les . Th ese gases a re prod uced

by e l e c t r ic a l d i sc ha r ge s . The p la sm a s t a te ha s p l a ye d a ke y ro l e in the e vo lu t ion o f

l i fe on ea r th and holds a grea t poten t ia l for fu ture. Apa r t f rom the proce ss of

n i t r oge n f ixa t ion w h ic h goe s on ye a r a f t er ye a r s du r ing thund e r ing o f c louds , l i gh t -

n ing a nd the ra ins , it i s be l i e ve d tha t t he f i rs t " l iv e " m o le c u le na m e ly~ the a m ino

a c ids we r e syn the s i z e d u nde r the c ond i t ions o f p l a sm a . Dur ing the p r im i t ive da ys

o f e a r th , n i t r oge n a nd hydr o ge n c o m b ine d to p r oduc e a m m onia , t he n c oup le d i t t o

m e tha ne a nd c a r bon d iox ide to syn the s i z e a m ino a c ids . I n sp i t e o f suc h a long

h i s to r y , the phe no m e no n o f e l e c tr i c al d i sc ha r ge s ha s be e n use d f o r po lym e r m od i -



3 9 6 P r e - t re a t m e n t o f T e x t i le s u n d e r P l a s m a C o n d i t io n s

f i c a ti ons ove r t he l a s t t h i r ty ye a r s o r so [ 15 -17] . Pa r t i c u l a r me n t i on ma y be m a de

of p i on e e r i ng w o rk done by G oo dm a n [ 18] , K a s s e nbe c k [ 19] , Pa v l a t h [ 20] , S p li t[21 ] and o thers [22 ,23] , for polym ers .

G e ne ra l l y s pe a k i ng t he r e a r e va r i ous fo rms o f a n e l e c t r i c a l d i s c ha rge w h i c h

d i f f e r in the i r e x t e rna l a ppe a ra n c e a nd t he t e mp e ra t u r e , de pe nd i ng on t he p r e s s u re

a nd t he vo l t a ge s ou rc e c onne c t e d t o the ga s s ec t ion . Th i s c u r r e n t f low i s b rou gh t

a bou t by i on i s a t i on t h rou gh a ga s, w he re by t he c u r r e n t f low i s p rod uc e d by a pp l y -

i ng h i gh vo l t a ge s . Fo r t e x t il e f i e ld s o f a pp l i c a t ion , f und a m e n t a l l y on l y " c o l d "

p l a s m a a n d i n p a r t ic u l a r t h e c o ro n a a n d g l o w - d i s c h a r g e a r e o f i n te r es t. " C o l d

p l a s m a " a r e unba l a nc e d p l a s m a o r l ow t e mpe ra t u r e p la s ma . The e le c t ron e ne rgy is

up to 100 ti me s g r e a t e r t ha n the e ne rgy o f the ga s pa r tc l es . " H o t p l a s m a " a r e know n

f rom nuc l e a r f u s i on . The e n e rgy o f e l e c t rons a nd ga s pa r t i c le s i s e qua l .

1 4 . 2 . 1 C o r o n a d i s c h a r g e

Thi s i s ge ne ra t e d a t ga s p r e s s u re s e qua l t o o r ne a r t o t he a t mos phe r i c p r e s s u re

w i t h a n e l e c t rom a gn e t i c f i el d a t h i gh v o l t a ge ( > 15 kV ) a nd f r e q ue nc y in the 20 -40

kH z r a n ge fo r mo s t p r a c t i c al a pp l i c a ti ons t oda y . I t de ve l ops w he n a h i gh vo l t a ge is

a pp l i e d t o e l e c trode s , bu t the i gn i t i on o f a s pa rk be t w e e n t he m i s p r e ve n t e d by a ni ns u l a t o r . I n o rde r t o t r igge r a c o rona d i s c ha rge , a h i gh f i e l d s t re ng t h m us t be p ro -

duc e d a t one e l e c t rode . Th rou gh h i g h vo l ta ge , t he e l e c t rons a r e a c c e l e r a t e d i n t he

di rec t ion of the insula tor . The insula tor i s s i tua ted d i rec t ly und er the subs t ra te to be

t r e a te d . O n t he i r w a y t o t he s ubs t r a te , t he e le c t rons c o l l i de w i t h a ir m o l e c u l e s a nd

fo rm o z one a nd n it r ic ox i de s i n t he p roc e s s . The e l e c t rons w h i c h r e a c h t he sub -

s t ra te a re due to the i r h igh e nerg y (appro x. 5 eV) and able to sp l it cova len t l inkages .

I n do i ng s o , r a d i c a l s a r e c r e a t e d on t he f i b r e s u r f a c e w h i c h r e a c t w i t h oz one o r

n i t r i c ox i de s , i . e . t he f i b r e s u r f a c e i s be i ng ox i d i s e d a nd t he r e by be c ome s more

po l a r i z e d .

1 4 .2 . 2 G l o w - d i s c h a r g e

Thi s i s ge ne ra t e d a t ga s p r e s s u re s i n t he 0 . 1 -10 MPa r a nge w i t h an e l e c t roma g -

ne t i c f i e ld i n a l ow e r vo l t a ge r a ng e ( i .e . 0 .4 -8 . 0 kV ) a nd a ve ry b roa d f r e que nc y

ra nge ( 0 -2 . 45 G H z ) . G l ow -d i s c h a rge ha s found p ra c ti c a l u s e i n f l uo re s c e n t t ube s .

A g l ow - d i s c ha rge i s b rough t a bou t w he n a n i nc r e a s e d vo l t a ge i s a pp l i e d t o t w o

e lec t rodes w hich a re spa ti a lly sepera ted in a conta iner wi th reduce d pres sure (approx.10 .3-10-4 bar ) . Due to the poss ib i l i ty of feeding in d i f fe rent gases , the sur fa ce o f a



P r e - t r e a t m e n t o f T e x t i l es u n d e r P l a s m a C o n d i t i o n s 3 9 7

s u b s t r a te t o b e t r e a te d c a n b e m o d i f i e d i n a c h e m i c a l l y s p e c i fi c m a n n e r .

B o t h f o r m s o f d i s c h a r g e s a r e r e g a r d e d a s a ' l o w t e m p e r a t u r e p l a s m a ' , b u t th et e r m ' p l a s m a ' is u s e d to d e s c r i b e t h e g l o w - d i s c h a r g e o n l y . C o r o n a d i s c h a r g e s a r e

g e n e r a l l y s u i t a b le f o r fl a t p r o d u c t s a n d s u b s e q u e n t p r o c e s s i n g i s d o n e i m m e d i a t e l y

a f t e r t h e t r e a t m e n t . I n c o n t r a s t to c o r o n a d i s c h a r g e , t h e e l e c t r o n s p r o d u c e d i n t h e

g l o w - d i s c h a r g e a r e o f h i g h e n e r g y , a s th e y a r e n o t s l o w e d d o w n b y c o l l i d in g w i t h

a ir m o l e c u l e s ( c o r o n a d i s c h a r g e s o r i g in a t e in a n ai r a t m o s p h e r e ) . G l o w - d i s c h a r g e s

a r e su i t a b l e f o r al l k i n d s o f te x t i l e p r o d u c t s a n d t h e i r e f f i c i e n c y d o e s d e p e n d o n t h e

t i m e e l a p s e d b e t w e e n t h e t r e a t m e n t a n d f u rt h e r p r o c e s s i n g . T h e e l e c t r o n s h a v i n g

b e e n c r e a t e d i n g l o w - d i sc h a r g e c a n a l so b e t te r p e n e t r a te t h e f i b re su r f a c e a n d t h e r e b y

a l so a l te r th e f i b r e su r f a c e m o r e i n t e n s i v e l y .

U n e v e n f i n is h e s c a n n o t b e r u l e d o u t in th e c a s e o f d e n s e a n d h e a v y f a b r i cs . I n

h e a v y f a b r i c , f o r i n s t a n c e , t h e w a t e r c o n t e n t s a t t h e c r o s s - o v e r p o i n t s o f th e i n d i -

v i d u a l y a r n s a r e v e r y h i g h , wh i l e n o n - o v e r l a p p i n g a r e a s o f t h e y a r n s h a v e r e l a t i v e l y

l o w m o i s t u r e c o n t e n t s . T h e s a m e a p p l i e s to th e i n d i v i d u a l f i b r e s i n t h e y a r n s t r u c -

t u r e. A s t h e c o n d u c t i v i t y o f t h e wo o l b e i n g a n i n su l a t o r i n it s d r y s t a te , i n c r e a se s

w i t h i t s m o i s t u r e c o n t e n t , g r e a t e r v o l t a g e g r a d i e n t s m a y o c c u r i n t h e " f i b r e - f r e e

a r e a s " t h a n a t t h e c r o s s - o v e r p o i n t s o f t h e f ib r e s a n d y a m s r e s p e c t i v e l y d u r i n g a

c o r o n a d i s c h a r g e . T h i s d o e s n o t a p p l y to f a b r i c s o f l o w f i b r e d e n s i t y , a s h e r e n o

s u c h l a r g e m o i s t u r e d i f f e r e n c e s o c c u r w i t h i n th e f a b r ic s t ru c t u r e a n d t h u s c o r o n a

t r e a t m e n t i s t h e m e t h o d t o b e c h o se n . I t c a n b e a p p l i e d i n a m o r e c o s t - e f f e c t i v e

m a n n e r t h a n t he g l o w - d i s c h a r g e w h i c h m u s t b e c ar ri ed o u t in a v a c u u m . A n e v e n

t r e a t m e n t o f fa b r i c s h a v i n g h i g h w e i g h t s o f s u r fa c e o r o f c o m b e d s l iv e r , h o w e v e r ,

is o n l y p o s s i b le w i t h th e a i d o f t h e g l o w - d i s c h a r g e . T h e p r e s s u r e r e d u c t i o n in t het r e a t m e n t c h a m b e r b e i n g n e c e s sa r y f o r t h e p r o d u c t i o n a n d m a i n t e n a n c e o f th e p l a sm a ,

l e a d s t o d r y i n g o f th e m a t e r ia l a n d t h e r e b y t o t h e e q u i l is a t io n o f m o i s t u r e d i f f e r-

e n c e s . I n a d d i t io n to th a t a h o m o g e n e o u s l y d i s tr i b u te d " p l a s m a c l o u d " a ls o d e v el -

o p s b e t w e e n t h e i n d i v i d u a l f i b r e s w h i c h a l l o w s a n e v e n t r e a t m e n t i n t h e d e n s e

fabr i c s t ruc tu re .

1 4 .3 G e n e r a t i o n o f P l a s m a a n d i t s A c t i o n

P l a s m a m a y b e p ro d u c e d b y :(i) t h e r m a l io n i s a t io n a t h i g h t e m p e r a t u r e s a t n o r m a l g as p r e s s u r e s , o r



3 98 P r e - t r ea tm en t o f T ex t i l e s u n d e r P l a s m a Co n d i t io n s

( ii ) b y u s in g e l ec tr i ca l d i s ch a r g e s - th e f r eq u en cy o f t h e e l ec tr i ca l en e r g y v a r y

f rom zero (d .c . ) to 10 ' ~Her t z (m ic r o w av es ) .T h e s e m ay b e s u b d iv id ed a s : ( a ) e l ec t r o d e d i s ch a r g es (g lo w , p l an e , p o in t , co r o n a

e t c .) an d (b ) e l ec t r o d e l e s s d i s ch a r g e u s in g rad io f r eq u en cy (RF ) a t l o w g as p r e s -

s u r e s. T h e u s e o f RF h as a fu r th e r ad v an t ag e t h a t it c an b e u s ed to b r in g ab o u t RF

h ea t in g . Var io u s t y p es o f e l ec t r o d e a s s em b l i e s can b e u s ed f o r i n i t ia t i n g p la s m a .

1 4 .3 .1 M a c h i n e p er f o rm a n c e f or p ro d u c i n g p l a sm a

T h e f ie ld o f i n d u s tr i a l p l a s m a en g in ee r in g h as g r o w n in r ecen t y ea r s. T h e u s es

a r e m o t iv a t e d b y p l a s m a ' s ab i l it y to acco m p l i s h i n d u s t r i a ll y r e l ev en t r e s u lt s m o r e

e f f i c i en t ly an d ch eap ly t h an co m p e t in g p r o ces s es . T h e re s ea r ch p r o g r am co n ce r n -

ing p lasm a t r ea tm ent o f t ex t i le mate r ia l s was launch ed a t the Po l i sh Tex t i le Ins t itu te

in 1973 to im prove the so i l r e lease p roper t ies o f double je r sey f abr ics f rom tex tur ised

p o ly es t e r y a r n s . T h e f i r st ex p e r im en t s w i th w o o l d a t e b ack t o 1 980 to r ep l ace t h e

ch lor ina t ion in f abric p repara tion fo r p r in ting . Three m achines fo r con t inuous p lasm a

t r ea tm en t o f w o o l t o p h av e b een d ev e lo p ed a s fo l l o w s :

- 1 983 F i r s t l ab o r a to r y d ev i ce w i th cap ac i t y o f ~ 2 k g / h

- 1 986 F i r st m ach in e w i th cap ac i t y o f ~ 2 0 k g / h- 1 992 F i r s t m ach in e w i th cap ac i t y o f ~ 4 0 k g / h .

For examp le , the shr ink p roof ing o f woo l us ing corona d ischarge has a l r eady r eached

a s t ag e o f co m m er c i a l p r o d u c t io n [2 4 ].

I t i s n e c e s s a r y t o r e c o g n i s e t h e d i f fe r e n c e b e t w e e n p o l y m e r f o r m i n g p l a s m a s

a n d n o n - p o l y m e r f o r m i n g p l a s m a s i n o rd e r to u n d e r s ta n d t h e tr u e m e a n i n g o f t h e

p r o ces s in g f ac to r s o f g lo w - d i s ch a r g e p o ly m er i s a t io n . N o t a ll g lo w - d i s ch a r g es y i e ld

p o ly m er d ep o s i t i o n . P l a s m as o f Ar , N e , 02 , N 2 an d a i r a r e t y p i ca l n o n - p o ly m er

f o r m in g p l a s m as . In ca s e o f p o ly m er f o r m in g p l a s m as t h e r e is p r e s s u r e ch an g e t h a t

o ccu r s b e f o r e , d u r in g an d a f te r th e g lo w - d i s ch a r g e . In t h e o th e r ca s e n o p r e s s u r e

ch an g e o ccu r s . A l th o u g h a n u m b er o f m e th o d s can b e u s ed t o g en e r a t e p la s m a , t h e

m e th o d s u t i l is ed i n s u r f ace m o d i f i ca t i o n o f t ex t il e s a r e m o r e o r l e ss l im i t ed t o

s o m e k in d o f e l ec tr ic d i s ch a r g e . T h e v o lu m e o f g lo w - d i s ch a r g e a s w e l l a s i n t en si t y

o f g l o w a r e h i g h l y d e p e n d e n t o n t he m o d e o f d is c h a r g e , th e d i s c h a r g e p o w e r a n d

p r e s s u r e o f th e s y s te m . T h e c h a m b e r w h e r e th e p o l y m e r i s m o d i f i e d i s k n o w n a s

th e r eac to r . T h e v o lu m e an d i n t en s i t y w i l l a ff ec t t h e r a te o f p o ly m er m o d i f i ca t io n ,dep endin g on the geom et r ic f ac to r s o f the reac to r . E lec t r ic d i scharge can be ob ta ined



P r e - t re a t m e n t o f T e x t i le s u n d e r P l a s m a C o n d i t i o n s 3 9 9

in n u m b er o f w a y s an d n u m er o u s co m b in a t i o n s o f f ac to r s a re in v o lv ed i n t h e d es ig n

o f r e a c t i o n v e s s e l. T h e t y p e o f e le c t ri c p o w e r s o u rc e a n d m o d e o f c o u p l in g a l sop l ay an im p o r t an t r o l e . Bas ed o n t h i s R . F . , l o w f r eq u en cy o r D . C . s o u r ce can b e

u s ed f o r ex c i t a t i o n an d co u p l in g can b e e i t h e r in d u c t iv e o r cap ac i t i v e .

F ig s . 1 4 - 1 t o 1 4 -5 d es c r ib e t h e t y p i ca l r eac to r s o f d i f fe r en t k in d s f o r p r o d u c in g

p la s m a . T h e d e s c r ip t i o n g iv en in t h e cap t io n is s e l f - ex p l an a to r y . F ig . 1 4 - 1 s h o w s

9 F l o w

:. ::iiiiiki -ii--~:-2~

V a c P u m p

F ig u r e 1 4 - 1 . T y p ica l l ab o r a to r y eq u ip m en t f o r g lo w - d i s ch a r g e ex p e r im en t s [ 2 5 ] .

t h e s ch em a t i c r ep r e s en t a t i o n o f g lo w - d i s ch a r g e r eac to r w i th in t e r n a l e l ec t ro d es .

T h e t w o c o p p e r e l e c t r o d e s i n t h e g l o w - d i s c h a r g e c h a m b e r s a r e 1 c m a p a r t a n d th e

f ab ri c s am p les a r e h e ld r ig id ly b e tw een th es e e l ec t ro d es . P o w er i s s u p p l i ed b y

5 00- W 3 . 1 4 MH z g en e r a to r . T h e ch am b er i s ev acu t ed t o 1 0 3 t o r r an d i f r eq u i r ed

m o n o m e r i s t h e n i n t r o d u c e d a t t h e a m b i e n t t e m p e r a t u re , i ts p re s s u r e a n d f lo w b e -

i n g r e g u l a t e d b y v a l v e s .

F ig . 1 4 - 2 s h o w s th e ex p e r im e n ta l a r r an g em en t t h a t i s n ece s s a r y t o b e m a d e f o r

p r o d u c i n g p l a s m a . I t c o n s i st s o f a c y l in d r ic a l g l a s s c h a m b e r h a v i n g a r r a n g e m e n t s

f o r co n n ec t i n g t o v acu u m p u m p , an i n l e t an d o u t l e t f or g as an d an i n le t to i n t r o d u ce

m o n o m er f o r t h e p u r p o s e o f g r a f t i n g ex p e r im en t s . A r ad io f r eq u en cy o s c i l l a to r ,

o p e r a t i n g a t 1 8 MHz can b e u s ed a s a s o u r ce t o p r o d u ce e l ec t r o d e l e s s d i s ch a r g e .

T h e p o w er o u tp u t can b e v a r i ed f ro m 1 00 to 2 5 0 w a t t s . T h e g a s p r e s s u r e i n s id e th e

tu b e m a y b e m a in t a in e d a t ab o u t 0 .1 m m o f r i g . A s p ec i a l g l a s s h o ld e r is d es ig n ed

to i n t r o d u ce t h e s am p le i n to t h e p l a s m a ch am b er . T h e s am p les a r e s u b j ec t ed t o

p l a s m a t r e a t m e n t f o r v a r i o u s d u r a t io n s o f t im e . O c c a s i o n a l l y a D . C . p o w e r s u p p l y



4 0 0 P r e - tr e a t m e n t o f T e x t i l e s u n d e r P l a s m a C o n d i t io n s

V al v e

: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . . 1 ~ .: 5.~a ~ 7;

F ig u r e 1 4 -2 . Sch em a t i c rep r e s en t a t i o n o f a g lo w - d i s ch a r g e

r eac to r w i th i n te r n a l e l ec t r o d es

o p e r a t i n g b e tw een 4 00 - 2 000 v o l t s is u s ed t o p r o d u c e g as d i s ch a r g e .

F ig . 1 4 -3 s h o w s s ch em a t i c r ep r e s en t a t i o n o f g lo w - d i s ch a r g e r eac to r w i th ex t e r-t

Ga~e k . , t ~ P 3R F

. - . . . [ I S h i e l d i n g ~ 1 | F l o w m e t e r

t _ ap a cm v e I !E l ec t r o d es , , .l [ ~

I " ~ , Ib Arg on-

substrate 5 0 f /

f " ~ _ . I I C o ax i a l

I f = ~ 1 i Generator ~--~AC- - " ~ . . . . . . . . . . . . . ~ _ . _ ~ _ . .. .. . . . , P o w e r

M o n o m e r T o V a c u u m

I n l e t ~ ~ P u m p s

F ig u r e 1 4 -3 . G lo w - d i s ch a r g e r eac to r w i th ex t e r n a l e l ec tr o d es .

na l e lec t rod es . A subs t r a te is p lac ed in the ta l l f r ame por t ion . F igs . 14-4 and 14-5

s h o w th e s ch em a t i c r ep r e s en t a t i o n o f co r o n a r eac to rs . F ig . 1 4 - 5 s h o w s th e co r o n a

r eac to r w i th a r o t a t i n g d r u m o n w h ich s u b s t r a te i s p l aced . T h e t y p e an d r a te o f

p o l y m e r f o r m a t i o n d e p e n d v e r y m u c h o n th e t y p e o f r e a ct o r.

T h e p r a c t i c a l a d v a n t a g e s o f te x t il e p l a s m a e x p o s u r e h a v e b e e n d o c u m e n t e d b y

R a k o w s k i [ 9] , w h o c o m p a r e d c o n v e n t i o n a l c h l o r i n a ti o n p r o c e s s w i t h a n e w p r o -

ces s b as ed o n t h e ex p o s u r e o f w o o l t o a l o w p r e s s u r e p l a s m a u s in g t h e ap p a r a tu s

s h o w n s ch e m a t i ca l l y i n F ig . 1 4 -6 . W o o l t o w is f ed co n t in o u s ly i n to a v acu u m



P r e - t re a t m e n t o f Te x t i l e s u n d e r P l a s m a Con d i t i on s 4 01

737

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I iI I

J I

Electrodes Ii 1 VacuumVessel

Vacuum Pumping4 DiffertiaiS t a g e s

Vacuum Pressure2-6 TorrProductionR a t e , 60 kg/h of Wool,T o t a l s u r f a c e a r e a , 3000 m-'/h

Fabl"icinput

DifferentialPumping Chambers

(4 s t a g e s )

F i gu r e 14 - 6 . Ap p ar a t u s f or l ow p r e s s u r e p l a s m a t r e a t m e n t o f w oo l [ 9 ] .

c h am b e r op e r a t i n g a t p r e s s u r e s o f 2 t o 6 t or r , w h e r e a g l ow - d i s c h ar g e p l a s m a p r o -

v i d e s ac t i v e s p e c i e s t o w h i c h t h e w o o l i s e xp os e d . A n ov e l f e a tu r e o f th i s ap p r oac h

Fabrico u t p ~ J

DifferentialPumping Chambers ~-.

(4 stages) i

51 mm ---- 24/40 groundg lassjoint

Figure 14 - 5. S c h e m at i c r e p r e s en t a t ion o f

F i gu re 14 - 4 . S c h e m at i c r e p r e s en t a t ion o f c or on a r e ac tor w i t h a r o ta t in g d r u m on

coron a reac tor , wh ich the subs trate i s p lace d .



4 0 2 P r e - tr e a t m e n t o f T e x t i l e s un d e r P l a s m a C o n d i t io n s

i s t h e c o n t i n uo us f e e d i n g o f t he w o o l t o w i n to a n d o u t o f t h e v a c uum s y s t e m t h r o ug h

s e v e r a l d i f f e r e n ti a l s t a g e s o f v a c u um p um p i n g .Mo r e r e c e n t l y , a g r o up a f f i l i a t e d w i t h S o f i a U n i v e r s i t y i n J a p a n [ 26 - 28 ] h a s

r e p o r t e d th e g e n e r a t i o n o f b o t h f i la m e n t a r y a n d g l o w - d i s c h a r g e p l a s m a s a t o n e

a t m o s p h e r e o f p r e ss ur e in s uc h g a s e s a s h e l i um , a n d a r g o n w i t h a n a d m i x tur e o f

a c e t o n e . S i m i l a r w o r k i s a l s o o r i g in a t e d i n d e p e n d e n t l y in t h e U T K P l a s m a S c i e n c e

L a b o r a t o r y a t t h e U n i v e r s i t y o f T e n n e s s e e i n K n o x v i l l e [ 2 9 - 3 4 ] . A s c h e m a t i c d ia -

g r a m o f th e o n e - a t m o s p h e r e g l o w - d i s c h a r g e p l a s m a r ea c to r s y s te m d e v e l o p e d a t

t h e U T K P l a s m a S c i e n c e L a b o r a t o r y is s h o w n in , F i g . 1 4 - 7 . T h e r e a c to r v o l um e i s

Heating" Element___ Pitot Tube , ~

Thermometer

Coolant \Dehumidifier "~

T = 5-10"F x.1,~,Gas Flow 3-8 LPM

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/

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t-~Con,ie~a~ Ti:a'~...... ---- . -~_. . . . . j -" ,W .Y

Figure 14-7. S chema tic d rawing of the one-atmosphere glow-discharge plasm a reactor [35].

b o u n d e d b y t w o p l a n e , p a r a l le l p la t e s a c r o s s w h i c h a k i l o h e r t z e le c t r i c f i e l d i s i m -

p o s e d . T h e e l e c t r i c f i e ld s m us t b e s t r o n g e n o ug h t o e l e c t r ic a l l y b r e a k d o w n t h e g a s

us e d , a n d a r e m uc h l o w e r f o r h e l i um a n d a rg o n th a n fo r a t m o s p h e r i c a i r. T h e

p a r a l l e l f a c e e l e c t r o d e s c o n s t i t u ti n g t h e d i sc h a r g e r e g i o n a r e p l a c e d i n a P l e x i g l a s

e n c l o s ur e . T h e w o r k i n g g a s is r e c i r c u la t e d a n d c h i l l e d to r e m o v e m o i s t ur e , a nd

rehe ated as required . The l ow er e l ec t ro de has a so l id s ta in l e s s s t ee l face and i sc o v e r e d w i t h a 3 . 2 m i l li m e t e r t h i c k P y r e x i n s u l a ti n g p la t e . T h e up p e r e le c t r o d e h a s

a p e r f o r a t e d f a c e o f s ta i n l e s s s t e e l w i t h 6 5 0 h o l e s 3 . 2 m i l l i m e t e r i n d i a m e t e r . G a s



P r e - tr e a t m e n t o f T e x t i le s u n d e r P l a s m a C o n d i t i o n s 4 0 3

f lo w i s i n t r o d u c ed o n th e b ack s id e o f t h i s e l ec t r o d e an d f l o w s d o w n w ar d t h r o u g h

th e p e r f o r a t ed f ace o f t h e e lec t r o d e . F ig . 1 4 -8 i s a s ch em a t i c d i ag r am o f t h e u p p e r

E L E C T ~

F ig u r e 1 4 -8 . E l ec t r i c f ie ld o f a r ad io f r eq u en cy p o w er b e tw e en

u p p e r an d g r o u n d ed m id p lan e e l ec t r o d es [ 3 5 ] .

c h a m b e r o f o n e - a t m o s p h e r e g l o w - d i s c h a r g e p l a s m a r e a c to r . T h e l o w e r b o u n d a r yo f t h i s s p ace i s t h e m id p l an e s c r een , th e f l o a t in g p o t en t i a l o f w h ich s h o u ld r em a in

n ea r g r o u n d i f t h e p o w er s u p p ly o u tp u t i s co n n ec t ed a s a p u s h - p u l l c i r cu i t to t h e

tw o e l ec t r o d es w i th a g r o u n d ed cen t e r t ap . T h i s r eac to r d o es n o t r eq u i r e an y v acu u m

s y s t em , an d o n ly a s im p le en c lo s u r e i s n eed ed i f o n e w i s h es t o o p e r a t e w i th g as es

o th e r th an a tm o s p h e r i c a i r .

T h e d i s co n t in u o u s (b a t ch ) m ach in e (F ig . 1 4 - 9 ) f o r f ab r i c t r ea tm en t d ev e lo p ed

.. .. .. .. .[ ................................... ~ . . ... .. , ............

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. . . . . . . . . . . . . . . . . . .

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.... [;L I~C_2~j....................

. . . . . . . . . . . . . . . . . . . ~ ~ 1 7 6

F ig u r e 1 4 - 9 . Ba t ch p l a s m a m ach in e KP R- 1 80 f o r f ab r i c t r ea tm en t [ 3 6 ] .



4 0 4 P r e - t r e a t m e n t o f T e x t i l e s u n d e r P l a s m a C o n d i t i o n s

b y t h e T e c n o p l a s m a S A c o n s o r t i u m i n S w i t z e r l a n d , b a s e d o n r e s e a r c h a n d c o n -

s t r u c t i o n w o r k p e r f o r m e d i n N i e k m i , R u s s i a , f o r t h e l a s t 1 6 y e a r s , h a s r e c e n t l yb e c o m e a v a i l a b l e as p r o d u c t i o n e q u i p m e n t .

T h e m o s t r e c e n t m a c h i n e f o r c o n t i n u o u s p l a s m a t r e a t m e n t o f w o o l t op d e v e l -

o p e d a t t h e T e x t i l e I n s t i tu t e i n Ld d z c o n s i s t s o f ( F ig . 1 4 - 1 0 ) a v a c u u m g e n e r a t i o n

_r l ~_7.. .. .. .. .. . 7i .......................... ,~,-.,I.,,l;]Ii:il ','r7 ........

A : : ~ .......L LIII~

B Topoi

C RF ~,mieldi~D RFd~w~-trodesE P l a s m a

F i g u r e 1 4 - 1 0. P r o t o t y p e m a c h i n e f o r c o n t i n u o u s p l a sm a t r e a t m e n t o f wo o l t o p [ 3 6 ].

u n i t , a p l a sm a g e n e r a t i o n u n it , a t o p tr a n sp o r t a n d c o l l e c t i n g sy s t e m . T h e g l o w -

d i s c h a r g e i s g e n e r a t e d i n a 4 5 . 8 l i tr e s p r o c e s s i n g c h a m b e r a t 1 3 . 5 6 M H z a n d a v e r -

a g e R F e n e r g y d e n s i t y o f 0 . 1 2 W / c m 3, p r o v i d e d t h a t t h e r e i s g o o d c o u p l i n g o f th eR F g e n e r a t o r a n d p l a s m a g e n e r a t i o n c i rc u i t. T h e m a c h i n e c a p a c i t y i s e s t i m a t e d a s

4 0 k g /h .

1 4 .3 . 2 T h e i n t e r a c t i o n o f p l a s m a w i t h s u b s t r a t e

T h e i n t e r a ct i o n o f p l a s m a w i t h m a t e r i a l s c a n b e r o u g h l y d i v i d e d i n t o th r e e d i f-

fe ren t c l a sses [37] :

( i) R e a c t i o n s d u e t o f o r m a t i o n o f i o n s wh i c h wo u l d l e a d d i r e c tl y t o a n e w c h e m i -

c a l p r o d u c t l i k e f o r m a t i o n o f NH 3, NO2,o z o n i sa t i o n e t c .

( ii ) T h e s e c o n d ty p e o f p l a s m a r e a c t i o n is t h e i n i t i a ti o n o f p o l y m e r i s a t i o n i .e .

d e p o s i t i o n o f t h in u n i f o r m p o l y m e r f il m o n t h e e l e c tr o d e s . O r g a n i c m o n o -

m e r s i n t h e v a p o u r p h a s e , l ik e o t h e r g a se s , a re i o n i se d b y b o m b a r d m e n t o f

e l e c t ro n s u n d e r t h e d is c h a r g e c o n d i t io n s . S u c h i o n s w h e n n e u t r a l is e d h a v e

e n e r g y w h i c h l e a d s o f r a p i d p o l y m e r i s a t io n . F i l m s h a v i n g g o o d s t a b i li ty ,

i n su l a t i n g p r o p e r t i e s , f r e e o f h o l e s a n d u n i f o r m t h i c k n e s s c a n b e o b t a i n e d a t

a r a t e o f f e w g r a m s p e r k w h . C o n t i n u o u s m o v e m e n t o f t e x ti le s , p a p e r e tc .

th ro ug h f l a t p l a t e e l ec t rodes (0 .1 m sepa ra t ion) fo r coa t ing i s poss ib l e . M anu -f a c t u r i n g o f t h i n f i lm f o r c a p a c i t o r s , c o a t i n g o f c a n s o r m e t a l su r f a c e s h a s

b e e n a c h i e v e d .



Pre- t rea tmen t of Text iles under P lasma Condi t ions 405

(ii i) The third type of plasm a react ion is concerne d with effects prod uced at or-

ganic polym er surfaces in contact with plasma. This type of react ion form s

the basis of m ajor develop me ntal work on text iles . The energic ions from

the plasma break organic bonds w i th the evolution o f gaseous produc ts ( for

e .g. hyd rogen from hyd rocarbon s) and the formation o f carbon free radicals .

These radicals can in turn lead to chemical react ions a t the surface of the

substrate [38,39].

The essent ia l plasma processe s are presented in Fig. 14-11. The process w hich

[Electric Field [I] Increasing the electron energy ]

i II Exci ta t i~ I I I~17 6 Iissociat ion]

Rad iat ion ] Reco mb inat ion I

I I

Ion-molecule react ion [

I Ch em ical react ion ] Etchnig ] Coat ing format ion ]

F igure 14-11. Bas ic process in plasma (Co urtesy o f Am ann un d S~hne G mB H).

can occur are cross-l inking, sol id-sta te polym erisat ion, e tching act ion, radical for-mat ion and degradat ion. W hich of these processes are predom inant , however ,

s t rongly depend on the nature of gas, pressure and the power used for the glow-

discharge. These react ions may be discussed under separate categories.

R e c o m b i n a t i o n 9W hen the ra te of prod ucing surface radicals is high an d air is

excluded, a tough cross-l inked shel l is formed that can offer protect ion against

solvent a t tack, penetrat ion by v apou rs or ions in solut ion or therm al disorientat ion.

This type of surface cro ss-l inking can be useful for" (a) l imit ing of plast ic izer loss

and extend ing the l ife ofp oly vin yl chloride t iles or other plast ic ized products , (b)

rendering water soluble products l ike polyvinyl pyrol idene p art ia lly w ater resis tant

for t ime delay encap sulat ion.



4 0 6 P r e - t r e a t m e n t o f T e x t i l es u n d e r P l a s m a C o n d i t io n s

Ox idat i on , Ox idat iv e degradat i on" I n o x y g e n c o n t a i n i n g p l a sm a , su r f a c e e x c i-

t a ti o n l e a d s t o a b s o r p t i o n o f o x y g e n a n d f o r m a t i o n o f p o l a r s u r f a c e o f k e to n e ,h y d r o x y l , e t h e r , p e r o x i d e a n d c a r b o x y l i c a c i d g r o u p s t h a t a r e m u c h m o r e h y d r o -

p h i l i c ( we t t a b l e ) t h a n t h e u n t r e a t e d su r f a c e . T h u s a r t ic l e s li k e fl a n n e l , p o l y p r o p y -

l e n e n o n - w o v e n f a b r i c s , P E f i l m , a n d T e f l o n h a v e s h o w n m a r k e d i n c r e a s e i n

w e t t a b i l i t y a f t e r e x p o su r e t o a i r d i s c h a r g e . C o r o n a d i s c h a r g e t r e a t m e n t i s r o u t i n e l y

a p p l i e d t o P E f i l m t o m a k e i t p r i n t a b l e . P l a sm a t r e a t m e n t c a n a l so le a d to i m -

p r o v e d a d h e s i o n p r o p e r ti e s ( t h r o u g h m e c h a n i s m d i s c u ss e d b e lo w ) .

P e r o x i d e f o r m a t i o n " A h i g h p r o p o r t i o n o f re a c t i v e s i t e s is c o n v e r t e d t o p e r o x -

i d e f o r m w h e n a t y p i c a l te x t i l e o r p l a s t i c su b s t r a t e i s e x p o se d t o A r g o n p l a sm a a n d

t h e n to a ir . I f R - H r e p r e s e n t s c a r b o n - h y d r o g e n b o n d s s u s c e p t i b l e t o t h e d is s o c i a -

t io n b y e x p o s u r e t o p l a s m a , t h e n

R - H Argo, , discharge ) , R * + H * - ~ H 2

( p o l y m e r w i t h C - H b o n d s ) $ a ir

R - O - O * ( p e ro x y r a d ic a l)

R - O - O * R -n > R - O - O - R + ra dic als + R - O - O - H

( p e r o x i d e )

S i n c e p e r o x i d e s a r e k n o wn t o a c t a s i n i t i a t o r s f o r v i n y l p o l y m e r i s a t i o n , i t f o l l o ws

t h a t u n d e r s u i t a b le c o n d i t io n s a v i n y l m o n o m e r w i ll re a c t w i t h p e r o x i d e g r o u p t o

p r o d u c e a g r a ft c o p o l y m e r w i t h th e s u b s t r a te , e . g .

C H 2 = C H - C O O H

R - O - O - H (ac,'ylic acid) > R O -C H ~_ + * C H - C O O H + * O H

peroxide site (propagating radical)

S i n c e p e r o x i d e g r o u p s a r e i n d e f i n i te l y s t a b le u n d e r a m b i e n t c o n d i t i o n s a n d t h u s ,

t h e y c a n b e s t o r e d a s r e a c t i v e s i t e s a n d u se d a t a l a t e r t i m e . T h e se s u r f a c e s a l so

s h o w i m p r o v e d a d h e s i o n i n d i f f e re n t c ir c u m s t a n c e s .

I n i t i a t io n f o r g r a f t in g 9T h e f r e e r a d i c a l s f o r m e d o n t h e su r f a c e o f f i b r e b y

e x p o s u r e t o p l a s m a c a n b e u s e d d i r e c tl y to i n it ia t e p o l y m e r i s a t io n , w i t h n e w p o l y -

m e r b o n d e d f i r m l y to th e s u r f a c e b y c a r b o n l i n k a g e s . T h u s , a n e w p o l y m e r c a n b e

a p p l i e d i n t h e f o l lo w i n g m a n n e r "

R - H discharge > R * .____Acr___yylic cid ), R C H 2 C H _ C O O H

C H 2 . * C H C O O H



Pr e - t r e a tm e n t o f Te x t i l e s unde r P la sm a C on d i t ions 40 7

1 4 .4 S u r f a c e M o d i f ic a t i o n o f F a b r i c s U n d e r P l a s m a T r e a t m e n t

The p la s m a - indu c e d su r f a c e m o d i f i c a t ion o f t e x t il e subs t ra t e s ha s ga ine d in -c r e a s ing im p or t a nc e o ve r the l a s t f e w ye a r s [40] . P r oba b ly the m os t a dva n ta ge

be h ind th i s r e ne w e d in t e r e st i n p l a sm a t e c hno logy i s t he r e s t r ic t ion o f the c onc e n-

t r a t ion o f AOX c om pou nds in the d i sc ha r ge d e f f lue n t s to 0 .5 m g/1 [41 ] . The o the r

r e a son f o r th i s i n t e r e s t is the in t r igu ing poss ib i l i t y o f m od i f y ing p r ope r t i e s l e a d ing

to be t t e r pe r f o r m a nc e . The r a nge o f a pp l i c a t ions i s d ive r se a nd m o d i f i c a t ions o f

su r f a c e o f va r ious m a te r i a l s l ike c o t ton , woo l , s il k , po lye s t e r h a ve b e e n r e por t e d .

P la sm a t r e a tm e n t ge ne r a l ly t a ke s p l a c e in d r y c ond i t ions , t hus the f ib r e s a r e no t

swo l l e n . The c ha n ge s in p r ope r t i e s induc e d by p la sm a t r e a tm e n t a r e the r e f o r e re -

s t r ic ted to the sur face and any damage to the in te r ior of the f ibre i s ve ry unl ike ly .

The ph ys ic o - c he m ic a l na tu r e o f the m o d i f i e d f ib re su r f a ce ha s a t r e m e n dous in flu -

e n c e o n t h e f o ll o w i n g i m p o r t a n t p h e n o m e n o n :

i ) S ta t ic e lec t r ic i ty bui ld up and d iss ipa t ion .

i i) M o is tu r e t r a nspor t a nd c om f or t .

i ii ) Oi ly s ta in adso rpt ion and re lease in de te rg ent so lu t ion .

iv) Soi l depo s i t ion , r e lease and redep os i t ion in de te rg ent so lu t ions .v ) W e t t a b i l i ty a nd a dhe s ion .

v i ) Sco urab i l i ty and b leac hab i l i ty of tex t i le s .

v i i) W e t t a b i l i t y a nd dye a b i l i ty

For m the phys ic a l po in t o f v ie w , r ough e n ing o f fib re su r f a c e a s s ee n by a tom ic

force mic ro sco py is r e spo ns ib le for chang es in the coef f ic ient of f r ic tion , top cohe-

s ion , sp inna bi l i ty , y am s t rength , e tc ., a s we l l a s for inc rease in fe l t ing res is tance of

woo l . F r om the c he m ic a l po in t o f v i e w , the ox ida t ion o f the fib r e su r fa c e a nd

in te r a c t ion wi th po lym e r ic m a te r i a l s a re the m a in f a c to r s r e spons ib le f o r im pr o ve -

m e n t s in va r ious p r op e r t i e s o f p l a sm a t r e a t e d m a te r i al s .

1 4 .4 .1 P l a s m a t r e a t m e n t o f w o o l

Th e e f fec ts of a p lasm a t rea tme nt on wo ol such as an t i - fe lt ing e f fec t, degreas ing ,

im pr ove d dye s tu f f a bso r p t ion a nd inc r e a se in we t t ing p r ope r t i e s ha ve be e n doc u-

m e n te d in num e r ou s pub l i c a t ions [42 - 46 ] . O the r cha nge s in woo l p r ope r t i e s a re

s u m m e r i s e d b e l o w :

( i) P las m a t rea tm ent inc reases the f ibre / f ibre f ric t ion as m easu red by RlJderm e thod [47 ], bu t r e duc e s the d i f f e r e n t ia l f r ic t ion e f f e ct ( DFE ) a s de f ine d

by M e r c e r [48] a nd L indbe r g [49] .



40 8 Pr e - t r e a tm e n t o f Te x t i l e s unde r P la sm a C on d i t ions

( ii ) P las m a t rea tm ent does not chan ge the s t rength and e longa t ion ; the break-

ing force in loop form is s l ight ly reduced.( ii i) Th e p lasm a t rea tm ent inc reases the top cohes ion by a fac tor of 1 .5-2 .0 ;

th is inc reased cohes ion remains s tab le a f te r pro longed s torage .

( iv) The spec i fic e lec t rica l r e s is t iv i ty does not change cons ide rably a f te r p lasm a

trea tment .

(v) The fa t ty mat te r content in wo ol is r educed by about one- th i rd due to p lasma

trea tment .

( v i) The w a te r c on te n t o f t he woo l top is r e duc e d by a bou t 3% due to p l a sm a

trea tment .

(v ii ) Th ere i s changes in sp inning beh avio ur o f p las m a t rea ted woo l [50 ,51 ] .

The sp inning a ids appl ied on the f i rs t drawing f ram e a re ca re fu l ly se lec ted .

The r ub b ing in t e ns i ty o r tw i s t o f t he s lubb ing shou ld be inc re a se d . R e duc -

t ion in breaks ra te a t r ing sp inning f rame is usua l ly obse rved and an in-

c r e a se in ya m te na c i ty by 20 - 25 % i s obse r ve d f o r a ll ya m s .

The n o r m a l p r oc e ss o f p r e pa r ing l igh t we igh t woo l l e n f a b r i c s has invo lve d a

chlo r ina t ion o pera t ion . Ho we ver , th is leads to d i f f icu l t wo rking condi t ions , r ap idcon-os ion of equ ipm ent and has a bad e f fec t on the loca l ecology. P lasm a t rea tment

i s a good a l t e r na t ive f o r c h lo r ina t ion t r e a tm e n t a l though two p r ob le m s r e m a in :

na m e ly the e f f i c ie nc y o f p l a sm a /po ly m e r sys t e m i t s e l f a nd the wa ys a nd m e a ns to

im p r ove the fa b r ic ha nd le [52] . How e ve r , p l a sm a t r e a tm e n t c ons ide r a b ly r e duc e s

the f e lt i ng po te n t i a l f o r a ny p r oduc t ob ta ine d f r om the m o d i f i e d woo l . The r e duc -

t ion in the c on te n t o f c ova le n t ly boun d h igh ly hydr oph ob ic m e thy l i c osa no ic a c id

and inc rease in content of oxid ised su lphu r spec ies a re the main fac tors respons ib le

f o r im p r ove m e n t s in dye ing a nd sh r inkpr oo f ing o f p l a sm a t r e a t e d woo l .

P la sm a t r e a tm e n t o f woo l f o l lowe d by po lym e r a pp l i c a t ion ha s a l so be e n s tud -

i e d [36] . A lm os t a ll po lym e r s u se d c u r r e n t ly on p r e - c h lo r ina te d woo l c a nno t be

use d on p la sm a - t r e a t e d top . S i l ic one r e sins a pp l i e d to p l a sm a - t r e a t e d woo l in -

c r e a se the sh r inka ge ove r tha t f o r un t r e a t e d woo l . How e ve r , t he c om bine d p la sm a /

PM S /He r c ose t t t r e a tm e n t e nc om pa ss ing the top t r e a tm e n t g ive s e xc e l l e n t sh r ink

r e s i s ta nc e [53 ]. The po lym e r a f t e r - tr e a tm e n t r e duc e s bo th re l a xa t ion a nd f e l t ing

sh r inka ge a lm os t i nde pe n de n t ly o f p l a sm a t r e a tm e n t t im e .There i s mo re even and quicker pene t ra t ion o f dyes tuf fs and chemica ls on p lasma-



P r e - t re a t m e n t o f T e x t i l e s u n d e r P l a s m a C o n d i t io n s 4 0 9

t r e a t e d woo l tha n the un t r e a t e d re f e r e nc e sa m ple . F ig . 14 - 12 show s the f ib r e c r os s -

F igu r e 14 - 12 . F ib r e c r os s - se c t ion o f theun t r e a t e d wo o l ( e n la r ge m e n t 30 0 0 0 X) .

F igu r e 14 - 13 . F ib r e c r os s - se c t ion o f thew o o l f o l l o w i n g p l a s m a t r e a t m e n t

( e n la r ge m e n t 30 0 00 X) .

se c t ion o f a n un t r e a t e d w oo l f ib r e w i th the f ib r e s t e m ( c o r t e x ) a nd the sc a l e l a ye r

( c u t ic u la ) , wh ic h i s m a de up o f the A- a nd B - l a ye r o f the c ys t ine r i c h e xoc u t i c u la

and the cys t ine poo re r endocut icula . Essent ia l ly A- layer of the exocut icula i s changed

by the p l a sm a t r e a tm e n t . F ig . 14 -13 r e ve a l s tha t t he A- la ye r o f t he c om be d s l ive r i s

a t t a c ke d to a d i f f e r e n t e x te n t by the p l a sm a t r e a tm e n t ( g low - d i sc ha r ge ) [54 ] . Th i s

m a n i f e s t s i t s e l f i n a pa r t i a l ly m uc h r e duc e d c on t r a s t a b i l it y a nd g ive s the A- la ye r a

" p e a r l - n e c k l a c e l i k e " a p p e a r a n c e in t h e e l e c tr o n m i c ro s c o p e . T h e i n c r e a s ed d y e s

a nd c he m ic a l s a f f in i ty is p r e su m a b ly a t t ribu te d to the p l a sm a induc e d o x ida t ion o f

the c ys t ine in the A- la ye r o f the e xoc u t i c u la a nd the r e by to a r e duc t ion o f the we t -

t ing br idge dens i ty in the f ibre sur face .

S ur f a c e a n a lyse s o f wo o l f ib r e s t r e a te d wi th d i f f e r e n t p l a sm a ga se s r e ve a l t ha t

the we t t a b i l i t y , w ic k a b i l i t y , p r in t a b i l i ty a nd su r f a c e c on ta c t a ng le o f the m a te r i a l s

a r e s ign i f i c a n t ly c h a nge d in a d i re c t ion tha t m a y l e a d to ne w use s f o r the se m a te r i -

a ls . Sev era l a spec ts a f fec t the w eb wet tabi l i ty , such as pore s ize , fibre d iam ete r ,

f ib re su r fa c e r oug hne ss and fib r e su r f a c e c he m ic a l c om pos i t ion . C h e m ic a l c om -

pos i t ion o f the f ib r e su r f a c e is m os t im por t a n t a s it de t e r m ine s the su r f a c e bond ing

f o r c e s w i th wa te r , i .e . d i s rup t ion f o r c e , po la r f o r c e , a nd H- bon d ing f o r ce . S u r f a c e

r oug hne ss i s no t a p r im a r y r e a son f o r im p r ove d we t t a b i l i ty , bu t i t m a y inc r e a se i t

[351.

Pla sm a t r e a tm e n t inc r e a se s the hydr oph i l l i c g r oups in the woo l f ib r e a nd thec ys t ine p r e se n t i n the su r f a c e l a ye r i s c onve r t e d to c ys t e i c a c id [55 , 56 ] . The



4 1 0 P r e - t re a t m e n t o f T e x t i l es u n d e r P l a s m a C o n d i t i o n s

e ndo c u t i c l e a nd the in te r c e ll m e m br a n e c om ple x a nd the de ns i ty o f c r os s - l inks in

the su r f a c e l a ye r i s de c r e a se d by the r e a c t ive spe c ie s in the p l a sm a ga s a nd thus

f a c i li t a t e d i f fus ion o f dye s a nd c he m ic a l s [57 ]. The in t er na l l ip ids o f ce l l m e m -

br a ne c om ple x a r e a lso m od i f i e d to a c e r t a in e x te n t [58 ]. The se c h a nge s in the

in t e r io r o f the f ib r e a r e p r e su m a b ly c a use d by the sho r t wa ve u l t r a - v io le t r a d ia t ion

w h i c h i s p r o d u c e d b y t h e l o w t e m p e r a t u r e g l o w - d i s c h a rg e p l a s m a a p a rt f r o m t h e

che m ica l ac t ive spec ies such as e lec t rons , r ad ica ls e tc . [59 ,60] .

W ool l e n s l ive r a nd ya r n ha ve be e n t r ea t e d in low t e m pe r a tu r e p l a sm a in a va c uum

c ha m be r f o r t im e s f r om 20 to 30 m in [61 ] . The r e i s a s ign i f ic a n t i nc r e a se in the

s t r e ng th w h ic h l e a d to be t t e r s t a b i li t y o f the m a te r ia l du r ing sub se que n t p r oc e ss ing .

Fa br i c s m a de f r om t r e a t e d woo l do no t f e l t a nd a l so the sh r inka ge i s r e duc e d e .g .

f r om 37 % to 3 - 5%.

P la sm a t r e a t e d woo l m a y e xh ib i t m or e o r l e s s f i r m o r ha r sh ha nd le be c a use o f

su r f a c e r ough e n ing . Th i s p r ope r ty is ve r y im por t a n t f o r ha nd - kn i t t i ng ya r ns o r

ya m s f o r und e r w e a r f a b ri c s . S o f t e ne r s ge ne r a l ly de te r io ra t e the sh r ink r e s i s t a nc e

im p a r t e d by p la sm a t r e a tm e n t o r p l a sm a p lus po lym e r a f te r - t re a tm e n t qu i t e he a v i ly

[ 3 6] . T h e e n z y m e t r e a tm e n t i s c a p a b l e o f im p r o v i n g t h e h a n d l e o f p l a s m a t r e at e dwo o l a s we l l a s p l a sm a t r e a te d a nd po lym e r a f t e r- t r e at e d ha nd- kn i t t ing ya r ns w i th -

ou t im pa r t ing the i r sh r ink r e s is t a nc e [62 ] .

1 4 .4 .2 P l a s m a t r e a t m e n t o f o t h e r f i b r e s

Pla sm a m a y be use d f o r r e m ov in g the c on ta m ina n t s , f i n i sh ing a nd s i z ing a ge n t s

f r om the f a b r ic . De s iz ing o f po ly e s t e r f a b ri c tha t u se d po lyv iny l a l c oho l a s the

s i z ing a ge n t c a n be r e m ove d by p la sm a t r e a tm e n t [63 ] .

The e f f i c ie nc y o f s cour ing , m e r c e r i z ing e t c . de pe nds on the pe ne t r a t ion o f wa te r

in to the f ib re a nd thus i ts we t t a b i l i t y The we t t a b i l i t y o f c o t ton a nd s i lk is i nc r e a se d

a f e w f o ld due to i t s p r e - t re a tm e n t by N 2 p l a sm a . I n c a se o f po lye s t e r f a b r i c s a l so

the we t tab i l i ty inc reases s igni f icant ly .

The e f f e c t ive ne ss o f t r e a t ing g r e y s t a t e a nd m e r c e r i z e d c o t ton a nd po lye s t e r /

c o t ton b le n ds in a low t e m pe r a tu r e p l a sm a be f o r e d ye ing i s r e po r t e d [641]. B o th a i r

a nd oxy ge n p la s m a t r e a tm e n t a l lowe d the sc our ing p r oc e ss to be e l im ina te d be f o r e

dye ing .

A p r oc e ss ha s be e n d e ve lop e d f o r b l e a c h in g t e x t i le m a te r i a l s c on ta in ing c e l lu -lo se a c t iva t e d by m ic r o w a ve r a d ia t ion [6 5 ]. H igh de g r e e o f w h i t e ne ss a nd c a p i l-



P r e - t re a t m e n t o f T e x t i l e s u n d e r P l a s m a C o n d i t i o n s 4 11

lary sorpt ion are obtained. Th e bleachin g can be car r ied out w ithout s i l icate s tabi l isers

w i th n o i n c r eas e i n o x id a t i o n d am ag e t o t h e ce l lu lo s e .T h e h y d r o p h o b ic e f f ec t o n a w o v en co t t o n f ab r i c can b e o b t a in ed b y s u r f ace

t r ea tm en t . P l a s m a t r ea tm en t w i th ac id as a co m p o n e n t o f o r ig in a l g as w i l l r e s u l t i n

a h y d r o p h i l i c s u r f ace [66] .

P o ly e s t e r f i b re s can b e e f fec t i v e ly m o d i f i ed b y l o w p r e s s u r e p l a s m a t r ea tm en t .

F o r y a m s t h e p la s m a s h o u ld b e c a p a b l e o f b e i n g i n c o r p o ra t e d i n to t h e f i ni s h ed y a m

p r o d u c t io n p r o ces s , d ep en d in g o n t h e en d - u s e o f t h e y am , a l t e r n a t iv e ly i t s h o u ld b e

p o s s ib l e t o ad d o n a p l a s m a t r ea tm e n t [67 ]. T r ea tm en t o f p o ly e s t e r f ib r e s b y g lo w -

d i s ch a r g e i n a ir o r o x y g en cau s es a p a r t i a l d eg r ad a t i o n o f t h e f i b re s u r f ace t o g e th e r

w i th an i n c r eas e i n th e cap i l la r y s o r p t i o n o f io d in e o r ca t i o n s i n aq u eo u s s o lu t io n

[68] . W e t t i n g o u t p r o p e r t i e s o f p o ly es t e r can b e ach i ev ed b y t r ea tm e n t o f p o ly es t e r

w i th p l a s m a an d co r o n a d i s ch a r g e [69] . T h e f ab r ic can b e p r o ce s s ed w i th o u t th e

u s e o f a w e t t i n g o u t ag en t . Gen e r a l l y , p o ly es t e r h as a v e r y h y d r o p h o b ic s u r f ace

b e c a u s e t h e s u r f a c e is m a d e u p o f e th e r o x y g e n ( C - O - C ) l i n k a g e s w h i le t h e h y d r o -

p h i l i c e s t e r o x y g en (C - O) is f ac in g t o w ar d s t h e co r e o f t h e fi b re . W h en s u r f ace

i s t r ea t ed b y p l a s m a e i t h e r t h e e s t e r o x y g en (C - O) co m es c lo s e r t o t h e s u r f ace a sa r e s u l t o f e t ch in g o r s o m e n e w C - O b o n d s a r e f o r m ed d u e t o o x y g e n io n s p r e s en t

i n t h e p l a s m a c h a m b e r .

So i l i n g o f f ab r i c s i s an o th e r im p o r t an t a s p ec t . T r ea tm e n t o f p o ly e s t e r w i th a ir

p l a s m a c o n s i d e r a b l y d e c r e a s e s th e s o il in g . D u r i n g p l a s m a t r e a t m e n t f a b r ic s g e t

n eg a t iv e ly ch a r g ed . T h e s o i l s a r e a l s o g en e r a l l y n eg a t i v e ly ch a r g e d an d t h e r e f o r e

th e r e is i n c r eas ed r ep e l l en cy . T h e p l a s m a e t ch in g i n c r eas es t h e h y d r o p h i l i c n a tu r e

an d th e r e f o r e t h e s o i l in g d ec r eas es . E t ch in g b y a ir p l a s m a cau s es g r ea t e r w e ig h t

lo s s o f n y lo n , co t t o n , s i l k o r w o o l f ib r e s t h an d o es e t ch in g b y ca r b o n t e t r a fl u r id e o r

n i t r o g e n p l a s m a , T h e d e g r e e o f s u rf a c e m o d i f ic a t i o n i s l o w e r f o r p l a s m a e t c h e d

n y lo n o r p o ly es t e r f i b re s t h an f o r co t to n o r w o o l f i b re s [70] .

A s m a l l s ca l e m e th o d f o r t h e p r ep a r a t i o n o f l i n en fab r ic i s d es c r ib ed w h ich

p r ac t i ca l l y e l im in a t e s t h e u s e o f ch em ica l r eag en t s [71 ] . T h e g r ey f ab r i c i s t r ea t ed

i n a g l o w - d i s c h a r g e p l a s m a i n a i r a n d t h en w a s h e d i n h o t w a t e r . T h e p r o c e s s m a i n -

t a in s t h e s t r en g th o f th e f ab r ic , d o es n o t a f f ec t t h e n a tu r a l co lo u r o f li n en an d d o es

g iv e f ab r i c a h ig h d eg r ee o f h y d r o p h i l i c i t y [72 ] .T h e e l ec t r o n m ic r o s co p ic s t u d ie s p r o v id e ad d i t io n a l i n f o r m a t io n r eg a r d in g m o r -



4 1 2 P r e - t r e a t m e n t o f T e x t i l e s u n d e r P l a s m a C o n d i t i o n s

p h o l o g i c a l c h a n g e s a s a r e s u l t o f p l a s m a t r e a tm e n t . D u e t o v e r y l o w r an g e o f

p e n e t r a t i o n t h e b u l k s t r u c t u r a l p r o p e r t y su c h a s c r y s t a l li n i t y o f t h e s a m p l e i s n o !

m u c h a f f e c t e d . P l a sm a e t c h i n g a l t e r s th e su r f a c e s t r u c t u r e o f co t t o n a n d s i lk c o n s i d -

e r a b l y . T h e f i b r i ll a r s t r u c t u r e is a p p a r e n t o n l y o n t h e u p p e r m o s t su r f a c e , wh e r e a s

d e e p d o w n i t d i s a p p e a r s . T h e su r f a c e o f t h e p o l y e s t e r i s v e r y sm o o t h i n i t i a ll y , b u t

p l a s m a tr e a t m e n t p r o d u c e s a t y p i c a l " s e a - s h o r e " s t ru c t u re . I n a d d i t io n in m o s t o f

t h e f i b re s t h e p l a s m a t r e a t m e n t s g i v e ri s e to t h e f o r m a t i o n o f s o m e c r a c k s , v o i d s

e tc . T h e t y p e o f s u r f ac e s t r u c tu r e p r o d u c e d d e p e n d s o n t h e t y p e o f g as a n d p r e s -

s u re . F o r e x a m p l e , t h e u s e o f n i t ro g e n , o x y g e n , a ir an d c a r b o n d i o x i d e t o r p o l y e s -

t e r g i v e s d i s t i n c t su r f a c e s t r u c t u r e w i t h s t r i a ti o n s a n d d e p r e s s i o n s . T h e u se o f C O~._

p r o d u c e s e v e n m o r e s i n g l e c r y s t a l s t r u c t u r e s . O n t h e o t h e r h a n d , th e u se o f H e , A r ,

NH 3 g i v e s l o w p r o f i l e su r f a c e s t r u c t u r e s .

1 4 . 5 H i g h E n e r g y R a d i a t i o n t o T e x t i l e s

E n e r g y so u r c e s f a l l c o n v e n i e n t l y i n t o t wo g r o u p s , v i z . h i g h e n e r g y i o n i s i n g r a -

d i a t i o n ( X- r a y s , a l p h a p a r t i c l e s , p r o t o n s , d e u t e r o n s , y - r a y s a n d e l e c t r o n s ) a n d l o w

e n e r g y r a d i a t i o n ( g a s d i s c h a r g e a n d u l t r av i o l e t) . I n t h e ca se o f r a d i a t io n p r o c e s s i n g

o f te x t i le s , o n l y y - ra y s f r o m r a d i o a c t i v e i s o t o p e s a n d h i g h e n e r g y e l e c t r o n s( [ 3 - r a y s ) f r o m m a c h i n e s a r e n e e d e d t o b e c o n s i d e r e d , y - r a y s a r e h i g h e n e r g y e l e c -

t r o m a g n e t i c w a v e s a n d h a v e g r e a t p e n e t r a t i n g p o w e r . A m o n g t h e r a d i o a c t iv e m a -

t er ia l s r e c o m m e n d e d a re C o b a l t - 6 0 a n d C e s i u m - 1 37. 1 - M e V g a m m a p h o to n s

l o se h a l f t h e i r in i ti a l e n e r g y a f t e r p a s s i n g t h r o u g h 1 0 c m o f m a t e r i a l o f u n i t d e n s i t y .

O n l y a sm a l l a m o u n t o f a v a i l a b l e e n e r g y i s i n g e n e r a l u t i l is e d w h e n t e x t i l e m a t e r i -

a ls a re i r ra d i a te d . T h e m a x i m u m d o s e r at e f r o m a p o w e r f u l C o b a l t - 6 0 s o u r c e is

a b o u t 2 M r a d /h , a n d s i n c e s e v e r a l M r a d s a r e n e e d e d t o e ff e c t s i g n i f i c a n t c h a n g e s

i n t h e m a t e r i a l , l o n g r e a c t i o n t i m e s a r e g e n e r a l l y n e e d e d . T h e i r r a d i a t io n so u r c e

d i c t a t e s th e t i m e o f e x p o s u r e . F o r e x a m p l e , r a d i a t i o n u s i n g u l t ra v i o l e t la m p re -

q u i r e s s u b s t a n t i a ll y l o n g e r t im e s . H o w e v e r , t h e a m o u n t o f r a d i a ti o n d o s a g e s d e -

p e n d s o n t h e k i n d o f f i b re ( T a b l e 1 4 .1 ). I t v a r i e s f r o m 2 M r a d f o r c e l l u l o s i c f i b r e s

t o t h a t o f a b o u t 4 0 M r a d f o r p o l y e s t e r f i b re ( 1 M r a d = l 0 s e r g /g o f su b s t a n c e ) .

W i th h i g h e n e r g y r a d i a t io n e l a b o r a te s c r e e n i n g a n d s a f e t y m e a s u r e s a re e s s e n t ia l ,

c a p i t a l c o s t s a r e h i g h , a n d t h e a c ti v e m a t e r i a l m u s t b e r e p l a c e d f r o m t i m e t o ti m e .

N e v e r t h e l e s s , y - r a d ia t io n i s u s e f u l w h e n l o w d o s e r at e s a r e r e q u i re d a n d w h e nt h i c k m a t e r i a l s o r r o l ls o f fa b r i c , a r e t o b e i r r a d i a t e d .



P r e - tr e a t m e n t o f T e x t i le s u n d e r P l a s m a C o n d i t i o n s 4 1 3

T A B L E 1 4 . 1

Gu id e Va lu e s o f I r r ad i a t io n D o s ag es [73 ].Subs t r a te R a d i a t i o n d o s a g e

M r ad

Cel lu lose 2 -3

Cel lu lose / syn the t ic 2 -3

P o l y a m i d e 5

P o ly ac r y l i c 5

P o ly es t e r 4 0

Cer t a in f i b re f o r m in g p o ly m er s h av e b een r ep o r t ed t o d eg r ad e an d t o c r o s s -l i n k

o n ex p o s u r e t o h ig h en e r g y r ad i a t io n . T h e r e l a ti v e ex t en t o f d eg r ad a t i o n an d c r o s s -

l i n k in g v a r i e s f r o m f ib r e t o f i b r e an d i s d ep en d en t u p o n r ad i a t i o n d o s e , t em p er a -

tu re , an d w h e th e r a i r i s ex c lu d e d d u r in g i r r ad ia t i o n [74 - 77] . Deg r ad a t i o n p r ed o m i -

na tes in ce l lu los ic f ib res , ce l lu lose ace ta tes , wool , po ly (v iny l id ine ch lor ide) and

p o l y t e t ra f l u o r o e t h y le n e , w h e r e a s p o l y e t h y l e n e , p o l y p r o p y l e n e , p o l y a m i d e s , p o l y -

e s t e r s an d p o ly ac r y lo n i t r il e a r e m o r e s u s ce p t ib le t o c r o s s -l i n k in g [78] .

T h e r e s u l t o f th e i n t r o d u c t io n o f r ad i a t io n w i th a p o ly m er is t h e c r ea ti o n o f fr ee

r ad i ca l s . T h e s e f r eq u en t ly r e s u lt f ro m th e o f b r eak in g C- H b o n d s l eav in g a p o ly -

m er r ad i ca l . T h e l a t te r u s u a l l y ab s t r ac ts an o th e r h y d r o g en f o r m in g h y d r o g e n g as

an d an o th e r p o ly m er r ad i ca l. T h e f a t e o f t h e r ad i ca l s d e t e r m in es w h e th e r th e p o ly -

m er ch a in d eg r ad e o r fo r m c r o s s - li n k . T h e m e ch an i s m b y w h ich t h es e cau s e e f fec -

t iv e c r o s s - l i n k i n g i s n o t c l e a r b u t p r e s u m a b l y t h e m o n o m e r a d d s t o th e m a c r o m o l -

ecu l e b e f o r e c l eav ag e , j u s t a s in t h e g r a f t i n g p r o ces s [79 ].

T h e u s e o f h ig h en e r g y r ad i a t i o n f o r t h e b l each in g o f t ex t il e m a te r i a l s h as b eenp a t en t ed [80] . A w id e r an g e o f p o s s ib i l i ti e s ex i s t s fo r m o d i f y in g b o th t h e p h y s i ca l

an d t h e ch em ica l p r o p e r t i e s o f t ex t il e s . B l ea ch in g o f t ex t il e s can b e d o n e e i t h e r b y

rad ia t ing the b lea ch ba th befo re the en t ry o f the f abr ic in to the b leach ing so lu t ion o r

th e f ab ri c m ay b e ex p o s ed t o r ad i a t io n an d s to r ed an d t h en b l each in g i s ca r r ied o u t.

T h e b l e ach b a th co n t a in in g s o d iu m ch lo r it e (5 - 1 10 g /l ) can b e ac t i v a t ed b y h ig h

en e r g y r ad i a t i o n , w i th p H ad ju s t ed t o 9 t o 1 1 . T h e ap p l i ca t i o n b a th s a l s o co n t a in

o th e r u s u a l ad d i t iv es s u ch a s o p t ica l b r i g h t en e r s , w e t t in g a g en t s an d au x i l i a ri e s an d

b l e a c h i n g c a n b e d o n e u s i n g c o n t i n u o u s o r b a tc h m e t h o d s a t o r b e l o w n o r m a l p r o -



4 1 4 P r e - tr e a t m e n t o f T e x t i le s u n d e r P l a s m a C o n d i t i o n s

c e s s ing t e m pe r a tu r e . The f re e r a d ic a l s a re f o r m e d w he n t e x t il e m a te r i a l s a re sub -

j e c t e d to m ode r a t e a m oun t s o f r a d ia t ion ( 1 - 2 M r a d) , so tha t t he fib r e de g r a da t ionc a n b e k e p t t o m i n i m u m .

Th e potent ia l o f u l t ra -v io le t or e lec t ron be am cur ing t rea tments on tex t i le s needs

f u r the r inve s t iga t ion a s suc h t r e a tm e n t s ha ve be e n use d in su r f a c e c o a t ing t re at--

m e n t s in the pa c ka g ing indus t r y [81 ] . The use o f a pp r opr ia t e po lym e r sy s t e m s w i th

a ppr opr i a t e f unc t iona l pe r f o r m a nc e p r ope r t i e s f o r u se w i th suc h tr e a tm e n t s m a y be

pa r t i c u la r ly va lua b le f o r su r f a c e t r e a tm e n t s u s ing UV c ur ing , a l though e l e c t r on

be a m c u r ing i s a n e xpe ns ive t e c hn ique [8 2 - 84 ] .

Ga s pha se o r va pour pha se t r e a tm e n t s i s no t ye t popu la r i n we t p r oc e ss ing o f

t e x t i le s . H ow e ve r , i n the a r e a o f ga r m e n t f in ish ing , t he d i f f ic u l t ie s o f tr e a tm e n t by

a ny o the r m e thod po te n t i a l ly r e nde r ga s pha se t r e a tm e n t s a t t r a c t ive , pa r t i c u la r ly

f o r t r e a tm e n t o f a c om pos i t e m u l t ip l e l a ye r s o f f a b r i c s , suc h a s in a ga r m e n t

[85, 86].

R E F E R E N C E S

1 K .R . M a k inso n a nd J . A . L e a d , P r oc . 5 th I nt . W ool Te x t . R e s . C onf . , Aa c he n .

Vol . 3 (1975) 315 .

2 A. E . Pav la th and K. S . Lee , Proc . 5 th In t. Wo ol Text . Res . Conf . , Aach en,

Vol . 5 (1975) 2 63.

3 M. M. Mil la rd , Proc . 5 th In t. W oo l Text . Res . Conf . , Aachen , Vol . 2 (1975)

44.

4 K. S . Lee and A. E . Pavla th , Text i le Res . J. , 45 (1975) 625 ,74 2.

5 K. S . Lee and A. E . Pav la th , Tex t i le Res . J ., 50 (1980) 42 .

6 A. E . Pav la th and K. S . Lee , M ak rom ol Sc i. Chem . , A 10 (3) (1976) 619 .

7 N. N. Be i la jev , Tieks t . p rom. , 5 (1977) 37.

8 W . R ako w ski e t a l ., M el l ian d Text i lbe r . , 63 (1982) 307 .

9 W . R a k ow sk i , M e l l i a nd Te x t i lbe r ., 7 0 ( 19 8 9) 78 0 .

10 H. L. R~) 'der, J . T ex ti le Inst . , 44 (6) (195 3) 247.

11 Fren ch P 1 ,19 7 , 146 (1959) .

12 Ge r m a n Pa te n t DE 4349 427 A 1 ( S a ndo I r on W or ks , J a pa n).

13 C ib a - Ge igy , Eur o pe a n P 0 559 6 0 9 .



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29 J . R. Roth , P. P. Tsa i and C . Liu, U. S. pate nt 5,387~842, Feb . 7 , 1995.

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31 J . R. Roth , P. P. Tsa i , C. Liu, M. Larou ssi an d P. D. Spe nce , U. S. paten t

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4 1 6 P r e - t rea tm en t o f Tex t i le s u n d e r P la sm a Co n d i t io n s

3 9 G. Franz , Kalte Plasm en, S pringer , Verlag, Berl in , 1990.

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48 E. H. Mer cer and K. R. Mak inson , J . Tex ti le Inst . , 37 (1946) 269.

49 J. Lind berg , Tex ti le Res. J. , 18 (1948) 480.

50 W . Rako ws ki, Proc. 9th Int . W ool Text . Res. Conf . , Biel la , Vol. 4 (1995) 359.

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52 L. L. Gorbeg et al ., Te kst i lpro m ., 11 (Nov 1989) 43.

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57 M. Lee and T . W akida , S en ' i Gak kaish i , 48 (1992) 699.

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60 D. T. Cla rk and A. Dilks, J. Polym . Sci ., Polym . Chem . Ed. 18 (1980) 1233.

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62 S .M . Sm ith et a l ., Proc. 9th Int . W ool Text . Res. Conf . , Biel la , Vol. 3 (1995)335.



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63 R. Ricc obo no, T ext i le Chem . Color . , 5 (1973) 219.

64 A. L . Tsr i sk ina , J . N. G ushchina , B . L . Go rberg a nd A. A. Ivanov , Refera t .

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67 M. Rab e et al ., M ell ian d Text i lber . , 75 (1994) 506.

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70 T. Yasud a e t a l., M uko gaw a Joshi Diagak u Kiyo Sho kum olsu-Ken. , 30 (1982)

A9.

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86 M. M. Morr i s , C . E . M orr i s and E. A. Cata lano T ext i le Che m. Co lor . , 28 (8)(1996) 50.



Chal~ter 15

A P P L I C A T I O N O F B I O T E C H N O L O G Y I N T H E P R E -T R E A T M E N T P R O -

C E S S E S O F T E X T I L E S

1 5 . 1 I n t r o d u c t i o n

B io te c hno logy c a n be de f ine d a s th e " a p p l i c a tion o f s c i e n ti f ic a nd e ng ine e r ing

pr inc ip le s to the p r oc e ss ing o f m a te r i a l s by b io log ic a l a ge n t s to p r ov ide goods a nd

se r v ic e s " . The e a r l i e s t e v ide nc e o f b io t e c hno logy inc lude ba k ing o f b r e a d us ing

yeas t by the anc ient Egy pt ians and brewing [ 1 . Ear ly methods of produc ing coloured

p igna e n t s f r om na tu r a l v i a b le sou r c e s m a y a l so be c i t e d a s p r im i t ive t e c hno logy

[2 - 6] . Tod a y e nz y m e s ha ve be e n u se d on a l ar ge sc a le in m e d ic ine , f ood a na lys i s ,

ge ne t i c a l ly m od i f i e d f ood , tr a nsge n ic a n im a l s a nd p la n t s a nd a lso in the dom e s t i c

de te r ge n t f ie ld s. Th e d i sc ove r y o f c he m ic a l s t ruc tu r e o f DNA ha s l ed to ge ne t i c

e ng ine e r ing , D N A f inge r - p rin t ing , ra p id ge ne se que nc ing a nd hos t o f r e l a te d t e c h -

no log ie s suc h a s p r oc e ss e ng ine e r ing , f e r m e n ta t ion , e nz y m o logy , dow ns t r e a m p r o -

c e s s ing , m ic r ob io logy , b ioc h e m is t r y , p r oc e s s c on t r o l , r e a c to r de sign , im m obi l i s e d

c e l l s a nd e nz ym e s , b iose nso r s , b iopo lym e r s a nd b io t r a ns f o r m a t ion [7 ] . M ode m

gene t ic techno logy i s cons tant ly produc ing n ew types o f appl ica t ion potent ia l which

wi l l c on t inue in the fu tu re . B io te c h no log y i s a l so inc r e a s ing ly ga in ing im por t a nc ein b io r e m e d ia t ion a nd in the c le a n up o f po l lu t e d e nv i r onm e n t s .

1 5 .2 E n z y m e s f o r T e xt il e A p p l i c a t i o n

I n t e x t i l e a pp l i c a t ion , t he knowle dge o f spe c i f i c a c t ion o f e nz ym e s - a m yla se s

for s ta rch sp l i t t ing beg an a rou nd 1857, wh en ma l t ex t rac t was used to remo ve s ize

f ?om f a b r i c s be f o r e p r in t ing [8] . The use o f e nz ym e in p r e - t r e a tm e n t p r oc e sse s o t

tex t i le s has found m uch b roade r acceptence . At present the pr ior i ty a reas a re scour-

ing a nd b le a c h ing o f c e llu los ic f ib re s a nd c a r bon i s ing , b l e a c h ing a nd sh r ink - r e s i s t

t r e a tm e n t o f woo l . Enz ym e s ha ve t r a d i t iona l ly be e n use d f o r s tone wa sh ing a nd

b io - po l i sh ing o f c o t ton f a b ri c s a nd ga r m e n t s . A l so e nz ym e s ha ve be e n inc o r po-

ra ted in de te rg ents to rem ov e f ibre fuzz and br igh ten the colour o f the fabr ic . In

c on t r a s t t o c e l lu lose a nd woo l l e n f a b r i c s , t he o the r m a r ke t s e gm e n t s inc lude s a

spec t rum of f ibres f rom l inen to lyoce l l (Tence l ) , r ayon (v iscose) and ce l lu lose

a c e ta te a nd a m u l t i tude o f b l e nds , w e igh t s a nd f a b r i c c ons t ruc t ions . W i th the a p -

pa r e l i ndu s t r y t r e nd towa r ds inc r e a s ing use o f c o tton kn i t s f o r a c h ie v ing n ove l ty

f in ishes i s obse rved .



A p p l i ca t i o n o f B i o t ech n o l o g y i n t h e P re - tr ea t me n t P ro ces s e s o f T ex t i l e s 4 1 9

1 5.2 .1 T h e c h e m i s t r y o f e n z y m e s

E n z y m es a r e n a t u ra l l y -o ccu r i n g p ro t e i n s cap ab le o f ca ta l y s i n g s p ec if i c ch emi -ca l r eac t io n s an d b e i n g ca t a ly s t s , f ac il it a te t h e r eac t io n w i t h o u t b e i n g co n s u m ed .

Af ter ca ta lys ing the che m ica l reac t ion , therefore the enzym e i s re leased and i s ab le

to ca ta lyse ano ther reac t ion-and so on .

En zym es hav e a p ro te in like s t ruc tu re wi th p r ima ry , secondary , t e r t i a ry and qua-

t e rn a ry s t ru c t u re s an d a r e s u s cep t i b l e t o d en a t u r in g (d eg rad a t i o n d u e t o t emp era -

tu re , ion i s ing rad ia t ion , l igh t , ac ids, a lka l i es and b io log ica l e f fec t fac to rs ). T he t ex-

t il e an d c l o t h in g s ec t o r is n o w a m a j o r u s e r o f en zy m es d u r i n g m an u fac t u r i n g an d

a f t e r- ca re . T ab l e 1 5 .1 s u m m er i s e s s o m e o f t h e a l read y i mp o r t an t e s t ab li s h ed en -

T A B L E 1 5 . 1

Imp o r t an t E n zy m es fo r T ex t i l e A p p l i ca t io n [ 9]

E n zy m es O r i g in E f f ec t

A m y l a s e

Ce l l u l a s e s an d

H emi ce l l u l a s e s

Pect inase

Baci l l ius Subt i l i s

Baci l l ius l i cker in forms

T r i ch o d e rm a r ae s ci

Asperg i l lus n iger

Asperg i l lus n iger

Pro teases Bac i l lius sub t i li s

B . L i ch en i fo rm i s

B . O r y z a e o f

Lipases Asperg i l lus n iger

M u c o j a v a n i c u s

Des iz ing o f s t a rches .

D es i z i n g o f je an s .

( A Q U A Z Y M ) m a k e s d e n ims t reak- f ree , so f te r and m ore

u n i fo rm l y f ad ed .

D es i z i n g o f CM C, s t y l is h

ef fec t s on ce l lu los ic f ib res ,

N o n - s t o n e t r ea t men t fo r

j earls.

Sco u r i n g o f v eg e t ab l e o r b a s t

f ib res l ike ju te , hem p, f lax ,

rem ie e tc .

Scou r ing o f an imal f ib res , o r

d eg u mmi n g o f s i l k , mo d i f i -

ca t io n o f w o o l p ro p e r t ie s .

E l i mi n a t i o n o f f a ts an d

waxes .

zy m es . C e l l u l a s e s a r e w i d e l y u s ed i n t ex t il e ap p l ica t io n . Ce l l u l a s e s a r e h i g h m o -



420 App l i c a t ion o f B io te c h no log y in the P r e - t r e a tm e n t P r oc e sse s o f Te x t i l e s

l e c u la r c o l lo ida l p r o te in c a t a lys t s i n m e ta bo l i c f o r m a nd a r e c om m o nly p r od uc e d

by so i l - dw e l l ing f ung i a nd ba c te r i a [ 10] . Indus t r i a l c e l lu la se s a r e c om ple xe s o f anu m be r o f c e l lu l a se s, c e l lob ia se a nd re l a t e d e nz ym e s in non- u n i f o r m c om p os i t ion ,

wi th m ole c u la r w e igh t r a ng ing f r om 10 ,0 0 0 to 4 ,0 0 ,0 0 0 [ 11 ] . C e l lu l a se s c om pr i se

a m u l t i c o m p o n e n t e n z y m e s y s te m , i n c l u d in g e n d o g l u c a l a s es ( E G s ) th a t h y d r o l y s e

c e l lu lose c ha ins r a ndom ly , c e l lob iohydr o la se s ( C B HS ) tha t sp l i t c e l lob iose f r om

ce l lu lose end s , and ce l lobiases tha t hyd rolyse ce l lobiose to g lucose . EG or EG-r ich

pr e pa r a t ions a r e be s t f o r a g ing a nd de f ib r i ll a t ion o f f ib r e su r f a ce s , wh i l e c om ple te

ce l lu lase sys tems a re bes t for c leaning and depi l l ing e f fec ts [12 , 13] . In genera l ,

t he r e a re two m a jo r c om m e r c ia l c l a s s if i c a tions o f c e l lu l a se e nz ym e s ba se d on op t i-

m um r a nge s 9 a c id c e l lu l a se s ' e xh ib i t the m os t a c t iv i ty w i th in the pH r a nge 4 .5 -

5 .5 , a t a tem pera ture o f 45-55~ ; wh i le 'neu t ra l ce l lu lase s ' ' , a re m ore e f fec t ive in

the 5 .5-8 .0 pH range a t 50-60~ Cu r rent ly , ac id ce l lu lases and neut ra l ce l lu lases

a r e m or e c om m on ly use d . W i th a lka l ine c e l lu l a se s, t he r e i s a poss ib i l i t y o f a pp ly -

ing the e nz ym e s in c om bina t ion w i th re a c t ive dye s f r om a dye ba th .

1 5 .2 .2 M e c h a n i s m o f e n z y m e a c t io n o n c o t t o n te x ti le s

En z y m e ' s e f f e c t m e c ha n i sm , i .e . e nz ym e c a ta lys is , ope r a t e s f i rs t o f a ll t o f o r ma n e nz y m e subs t r at e c o m p le x [ 14] . D i r e c t phys ic a l c on ta c t o f e nz ym e a nd sub -

s t ra t e is re qu i r e d to ob ta in the c om p le x . Th e c u r r e n t p r opose d m e c ha n i sm o f c e llu -

l a se a c t ion i s i l lu s t r a te d in F ig . 15 -1 . Howe v e r , t he m e c h a n i sm o f e nz ym a t i c hy -

C e l l u h ~ : b : l ~ l e , ~

C l ~ . s t a l l i n e A m o r p h o u s

r e g io n s ~ , ==- ~ . . . . ~ r e g io n s

1a E n d o - b - g l u c a n a s e ( E G s )

-

9 . r " - . . * ' . , - "

Ib C e i l o b i o h y d r o l a s e s . ( C B H s )

~ _ - .- =- -- -' - -' - " ~== 5 : := ~ " _ " _ ~ ~

~ . ~ e . . ~ . ~ - : - : _

..

c C B H

9 E G

d= . . . . . . . . . . = . . . . . . . . . . . . . . . . . . . . . . - ~ . . . . ~ * G l u c o s e

Figur e 15 -1 . S c he m a t i c r e p r e se n ta t ion o f syne r g i st i c

a c t i o n o f e n z y m e s o n c e ll u l o s i c s [ 1 5 ] .



App l ica t ion o f Bio techn ology in the Pre- t rea tm ent Processes o f Tex t i les 421

d r o ly s i s o f c e l lu lo s i c m a te r i a l s i s co m p l i ca t ed an d n o t y e t f u l ly u n d e r s to o d

[16-18] . Enzymes con ta in t rue ac t iv i ty cen t re in the fo rm of th ree d imensiona lstructures l ike f issures, holes, pockets, cavit ies or hollows. End ogluca nases or endo-

ce l lu lases hydro ly se ce l lu lose po lym ers random ly a long the cha ins , p re fe rab ly a t-

tack ing no n-crys ta l l ine reg ion [ 19] . Ce l lob iohydro lase s o r ex o-ce l lu lases , a t tack

the po lymer cha in ends and produce ce l lob iose [20] . Coupled wi th the b ind ing

domains assoc ia ted wi th the enzyme, exo-ce l lu lases may ass is t in degrada t ion o !

ce l lu lose by d isrup t ing the loca l c rys ta l l ine ce l lu lose s t ruc tu re , which makes the

r e g i o n m o r e s u s c e p t i b l e t o s u b s e q u e n t h y d r o l y s i s b y e n d o - c e l l u l a s e s [ 2 1 ] .

F ig . 15-2 shows the reduc ing and non- reduc in g end groups by the a c t ion o f ce llu -

O H O 3 O H

C e l l u l a s e a H ~

~ 0

R e d u c i n g E n d G r o u p N o n - R e d u c I n g E n d G r o u p

~ ~ . ~ A 0 + , C u ( O H } 2 o r F e r r l c y a n l d e

A g ~ , C u 2 0 ~ 1 , o r F e r r o c y a n l d e

o

Figure 15-2 . Enzym at ic hydro lys is o f co tton ce l lu lose [22] .

lase on 1 ,4 - [3 -g lycoside bond o f the ce l lu lose m olecu le . [3 -g lucosidases hydro lysc

smal l cha in o l igom ers , such as ce llob iose in to g lucose . The th ree types o fce l lu lasc

com pon ent ac t synerg is t ica l ly in degrad ing ce l lu lose to g lucose . Syn erg ism of d i f-

fe ren t compo nents in the ce l lu lase com plex and inh ib it ion m echan ism s fu r ther com-

pl ica te the reac t ion [23 , 24] . Enzym e d i f fus ion p lays a m uch m ore dec is ive ro le in

the he te rogeneous sys tem of so lub le enzyme and so l id subst ra te . The k ine t ics o !reac t ion therefore depe nd on the d i f fus ion o f enzym e to and in to the so l id phase o !



4 2 2 A p p l i c a ti o n o f B i o t e c h n o l o g y i n th e P r e - tr e a t m e n t P r o c e s s es o f T e x t i l e s

the su bs t r a t e a nd the d i f f us ion o f the r e a c t ion p r od uc t s o u t o f t he so l id pha se in to

the l iquor . Fo r co t ton , the res t r ic t ion o f the enzy m e to the f ibre sur face i s eas i lya c h ie v e d be c a u se c e l lu lose i s a h igh ly c r ys t a l l ine m a te r ia l a nd posse s se s on ly sm a l l

a m or phous a r e a s , m a k ing the d i f f us ion o f e nz ym e s in to the in t e r io r o f t he f ib r e

n e a r l y i m p o s s i b le . T h u s , b y r e g u l a ti n g e n z y m e d o s a g e a n d c h o o s i n g t h e r ig h t t y p e

of e nz ym e , the c a t a ly t i c a c t ion o f the e nz ym e c a n be c onf ine d to the su r f a c e o f

c o t ton a n d to the a m o r phou s r e g ions , l e a v ing the f ib r e s , as a wh o le , i n t a c t [25 ].

1 5 .2 . 3 P a r a m e t e r s g o v e r n i n g t h e e e ll u la s e tr e a t m e n t s

T h e c e l lu l a s e m u l t i - e n z y m e c o m p l e x i s co m p l e te l y n o n - u n if o r m . A d d e d t o t h a t

i s subs t r a t e spe c i f i c i ty in the f o r m o f a s e l e c tive su i t a b i l it y f o r e nz ym a t i c de g r a da -

t ion , due to non- un i f o r m s t r uc tu r e o f c o l lu lose . Ya m type , s t r uc tu r e a nd t e x t i l e

subs t r a t e a l so in f lue nc e the b r e a k - do w n e f f ec t . F ine ya m s a nd ope n m a te r i a l c on -

s t ruc t ions , pa r t icu la r ly any f ree ly access ib le pro jec t in g f ibres, a re spec i f ica l ly sus-

c e p t ib l e to de g r a da t ion . P r io r to e nz ym a t i c t r e a tm e n t a ny im pur i t i e s o r a dd i t ive

p r e se n t ha ve to be r e m ov e d f ir st . In pa r t i c u la r , t he subs t r a te m u s t be f r e e f r om a ny

e n z y m e t o x i n s . S o m e o f th e e n z y m e t o x i n s re c o g n i s e d a r e f o rm a l d e h y d e c o n t a i n -

ing f in i sh ing a ge n t s , t a nn ic a c ids l i ke na tu r a l t a nn in o r po lyphe no l i c f a s tne s s a f te r -t r e a tm e n t a ge n t s , p r o te a se s , spe c i fi c su r f a c t a n ts a nd m ic r ob ioc ide s . De na tu r ing c a n

occu r throug h sp ec i f ic s torage e f fec ts . In genera l buf fe red granula tes a re mo re s tab le

f o r s to r a ge . Th e p r e se nc e o f c he m ic a l subs t a nc e s suc h a s o r ga n ic s a lt s , i ron , m a g -

ne s ium a nd z inc ions e t c. c a n e i the r e nha nc e o r inh ib it e nz ym e a c t iv i ty [26 ].

B o t h p H a n d t e m p e r a t u r e a r e c r i t i c a l f a c t o r s a f f e c t i n g c e l l u l a s e t r e a t m e n t

(Fig . 15-3 and Fig . 15-4). A par t icu la r type of ce l lu lase w i l l only op era te und er a

spe c i f i c pH a nd t e m p e r a tu r e op t im a a nd i t s a c tiv i ty w i l l de c r e a se sha r p ly on bo th

l o g - - -+ / " "m . . . . .. . . . .. . . .

!

/2a /

i

( ' 2 4 6" 8 i0p H

.=- 68

.,~

9 48

88 /

. - 68 / \

9~ 48 ] \.~ . j sO+ \

t \2 8 ] \

~ _ _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ),__ .0 28" . . . . 38 48 58 - - 6 8 7 8 - " - t i8

T e m p e r a t u r e ( " C )

Figur e 15 -3 . pH de pe nd e nc y o f ce l lu l a se

activi ty.

F igu r e 15 -4 . E f f e c t o f t e m p e r a tu r e on

cellulase act ivi ty.



A p p l i c a t i o n o f B i o t e c h n o l o g y i n t h e P re - t re a t m e n t P r o c e s s e s o f T e x t il e s 4 2 3

s id es o f t h e o p t im u m r an g e . N eu t r a l ce l l u l a s e i s ad v a n t ag eo u s a s it i s s t ab le o v e r a

b r o ad e r r an g e . Ge n e r a l l y , a t r ea tm en t t im e o f 4 5 - 1 2 0 m in i s ap p r o p r i a t e a s p r o -long ed t r ea tm ent t ime m ay increase the fib re loss s ign i f ican t ly . S im i lar ly , excess ive

ce l l u l a s e d o s ag e m ay a l s o i n c r eas e t h e w e ig h t l o s s %. T h e d eg r ee o f ag i t a t io n a l s o

co n s id e r ab ly i n c r eas es t h e w e ig h t l o s s . Mach in es w i th v ig o r o u s ac t i o n s u ch a s a

l au n d e r o m e te r cau s e a m u ch g r ea t e r w e ig h t l o s s t h an d o es h an d s t i r r i n g . T h e d e -

c r eas e i n b u r s t i n g s t r en g th i s r o u g h ly p r o p o r t i o n a l t o th e w e ig h t l o s s o f th e f ab r ic .

T h e d ec r eas e i n d r ap e co - e f f ic i en t an d t h e f l ex u r a l r i g id i ty a r e ap p a r en t an d h en ce

l ead s t o th e im p r o v e m en t i n t h e h an d le o f t h e co t t o n k n i ts a f t e r ce l lu l a s e t r ea tm en t .

15.2 .4 Changes of structures and morphology of f ibres by enzymatic hydrolysis

T h e ce l l u l a s e co m p lex d i f f u s es t h r o u g h th e p o r e s y s t em to th e m ic r o f ib r i ls , a t -

t ack s t h e ce l l u lo s e ch a in s a n d h y d r o ly s e s each ch a in to th e en d . T h e d i f f e r en ces in

th e e ff i cacy o f c e l l u l a s e s o n v a r io u s f ib r e s a r e d ep en d en t o n n u m b er o f f ac to r s s u ch

a s t h e a m o u n t s o f n o n - c e l l u l o s i c w o o d p u l p - d e r i v e d m a t t e r , th e d e g r e e o t

p o ly m er i s a t i o n , t h e t y p e an d d eg r ee o f c r y s t a ll i n it y , an d t h e t y p e an d n u m b er o f

ch em ica l s u b s t i t u t io n s t o t h e ce l l u lo s e [ 2 7 - 3 0 ] . Key f ea tu r e s f o r th e ce l l u lo s e s u b -

s t r a te a re c rys ta l l in i ty , acc ess ib le su r face area and pore d im ens ions [31 ] . Var ia t iono f an y o f t h es e f ac to rs , e . g . , s tr u c tu r a l ch an g es o f ce l l u lo s e s u b s t r a t e b y p r e - t r ea t -

m e n t s , w i l l i n f l u en ce t h e co u r s e o f t h e en t ir e d eg r ad a t i o n p r o ces s [ 3 2 , 33 ] .

Vi s co s e r ay o n i s i n h e r en t ly a w eak f ib r e , p a r t i cu l a r ly w h en w e t , t h e r e f o r e i t is

h ig h ly s u s cep t ib l e to d am ag e i f en zy m at i c h y d r o ly s i s i s n o t co n t r o l led . T h e en zy -

m a t i c h y d r o ly s i s o f v is co s e f ib r e s cau s es a d ec r eas e o f t h e i n t ri n s i c v i s co s i t y f r o m

250 to 140 ml /g and an increase in c rys ta l l in i ty f rom 29 to 39% af te r 44 h [34] .

S t r o n g ch a n g es o f t h e s tr u c tu re , h o w ev e r , a r e n o t t y p ica l f o r t h e en zy m at i c h y d r o ly -

s is o f ce ll u lo s ic m a te r ia l s . N e i th e r co t t o n n o r w o o d p u lp s h o w an e s s en ti a l d ec r eas e

o f t h e DP d u r in g en zy m at i c h y d r o ly s i s [ 3 5 - 3 7 ] . T h e k in e t ic s o f t h e en zy m at i c h y -

d r o ly s i s o f reg en e r a t ed ce l l u lo s e f i b re s b e f o r e an d a f t e r ac id p r eh y d r o ly s i s ch an g es

th e k in e t i c s f r o m a m o n o p h as i c t o a b ip h as i c f ir s t o r d e r r eac t i o n [3 8] .

Bas t f i b r e s l i k e l i n en an d r em ie a r e m u l t i p l e ce l l u l a r s y s t em s , i n co n t r a s t t o

co t to n , w h ich co n s i s t s o n ly o f a s i n g l e ce ll . M u l t i ce l l u l a r f i b r e s co n t a in n a tu r a l

g u m s an d r e s in s t h a t k eep t h e ce l l t o g e th e r . C r y s t a l l i n i t y i n d i ces o f co t t o n , l in en ,

r em ie an d v i s co s e f i b r e s d o n o t ch an g e a f t e r t h e en zy m at i c h y d r o ly s i s , n o r d o esacces s ib i l i ty to mo is tu re [39] . Conse quen t ly , ne i ther the r a t io o f c rys ta ll ine to amor -

p h o u s m a te r i a l n o r t h e DP o f t h e re s id u e ch an g es s i g n i f i can t ly [ 4 0] .



4 2 4 Ap p l i ca t i o n o f B io t ec h n o lo g y in t h e P r e - t r ea tm en t P r o ces s es o f T ex t i l e s

1 5 .2 . 5 T h e u s e s a n d a d v a n t a g e s o f e n z y m a t i c p r o c e s s i n g

Re cen t ly en zy m es a r e u s ed i n t ex t il e ap p l i ca ti o n . T h e u s e o f en zy m e in d eg r ad -in g s t a r ch h as b een k n o w n . E n zy m e t ech n o lo g y i s o f g r ea t i n t e r e s t i n t h e ch em i -

ca l l y d em an d in g p r e - t r ea tm en t o f co tt o n , w o o l an d s i l k f ib r e s. Ce l lu l a s e s can b e

u s ed t o f i n is h t r ea tm en t s o f co t t o n p e r t a in in g t o f ab ri c s o f tn ess , g o o d p e r f o r m a n ce

an d f a s h io n ab l e l o o k s a s w e l l a s t h e p o t en ti a l t o sim p l i f y an d ch eap en m a n u f ac tu r -

i n g p r o ces s es . P o p u la r u s es p e r h ap s a r e s t o n e - w as h in g o f d en im j ean s an d b io -

p o l i s h in g . E n z y m es a r e a l so u s ed f o r d eg u m m in g o f s i lk an d b as t f ib r e s , rem o v a l

o f s k in r e s id u es an d v eg e t ab l e m a t t e r f r o m w o o l an d an t i - fe l t in g an d s u r f ace m o d i.-

f i ca ti o n o f w o o l . C e l lu l a s e s s h o w g r ea t p r o m is e i n te r m s o f e f f ec t i v en es s an d t h e

en t i re p r e - t r ea tm en t p r o ce s s es d o n o t ap p ea r t o b e b ey o n d th e b o u n d s o f p o s s ib i li t y

in t h e f u tu re . In s o m e o f t h e p r o ces s e s t h e en zy m e t r ea tm en t i s co m b in ed w i th

m ech an ica l ac t i o n to en h an ce t h e acces s ib i l i ty o f co t t o n s u b s t an ces . An o th e r ap -

p r o ach i s t h e co m b in a t i o n o f p l a s m a t r ea tm en t w i th en zy m e t r ea tm en t [ 41 ] .

T h e f o l l o w in g p o in t s a r e ach i ev ed i n p r ac t i ce :

i) T h e en zy m a t i c p r o ces s r em o v es th e s m a l l f ib r e en d s f o u n d in y a m s u r face

which even tua l ly lead to p i l l ing on the f abr ic su r face .i i) Kn i t ted f abr ics t r ea ted wi th ce l lu lases a re f ree f rom surface ha i r iness , neps ,

f l u f f an d k n o p s w i th m u ch im p r o v ed h an d le an d f l ex ib il it y .

i ii ) Th e m ater ia l s t i ck ing ( the bu r r e f f ec t ) i s p rev en te d par t icu lar ly wi th m er -

ce r i zed k n i t t ed f ab r ic . M a te r ia l t ex tu r e r e l ax a t io n t ak es p l ace an d im p r o v e

sewabil i ty .

i v) T h e e f f ec t o f t r ea t em n t is l o n g la s t in g . T h e co lo u r o f t h e d y ed g o o d s b e -

co m e b r ig h t e r w i th a v is u a l im p r o v ed co lo u r y i eld .

v ) The p rocess is par t icu lar ly su i tab le fo r the p re- t r ea tm ent o f nappe d , knop py

g o o d s w h en th e r e a re n o s u i tab l e c l ean in g , b ea t in g , b r u s h in g an d s h ea r in g

m ach in es av a i lab l e .

v i ) Co m p le t e o r p a r t ia l r ep l ace m en t o f p u m ice s to n es b y ce l l u l a s e en zy m es

f o r t h e e ff ec t o f ' s t o n e - w as h in g ' o n d en im i s w e l l e s tab l i s h ed an d t h e co n-

cep t o f ' b io - p o l i s h in g ' , w h ich o r ig in a t eed i n J ap an h as b een ex t en d ed t o

l~ i t t e d s t r u c tu r e s an d b l en d ed f ab r i c s.

v i i) Ce l lu l a s e s h av e b een i n co r p o r a t ed i n d e t e r g en t s to r em o v e t h e f ib r e fu zzan d th i s m ean s b r ig h t en t h e co lo u r s o f t h e f ab r ic s .



A p p l i c a t i o n o f B i o t e c h n o l o g y i n t h e P r e -t r e a tm e n t P r o c e s s e s o f T e x t i l e s 4 25

v i ii ) An o th e r ad v an t ag e o f en zy m at i c p r o ces s es i s t h a t t h ey can b e ad o p ted t o

r u n o n eq u ip m en t a l r ead y ex i s t i n g i n tex t i le p l an t s.i x ) T h e m e th o d i s o f i n t e r e s t f r o m th e v i ew p o in t o f en e r g y s av in g s , p o l l u t i o n

co n t r o l an d s a f e ty . Bec au s e t h e ce l l u l a s e en zy m e , b e in g a b io ca t a ly s t , o f -

f e rs a d v a n t a g e s s u c h a s e n e r g y s a v i n g s th r o u g h l o w e r t r e a tm e n t t e m p e r a -

tu r e s o f 4 0 - 5 0~ T h e en zy m at i c p r e - t r ea tm en t s o f t ex t i l e s a r e n o t so

ag g r as iv e t o f ib r e s an d en v ir o n m en t . T h e ' c l ean ch em is t r y ' a p r o ach es is an

ad v an tag e i n co m p ar i s o n t o t h e p o w er f u l a lk a l i e s , a c id s , o x id i s e r s an d r e -

d u ce r s n eed ed i n t r ad it i o n a l p r o ces s es , t en d in g t o a t t ack t h e t ex t il e m a te -

r ia l as wel l as caus ing co ns iderab le co n tam inat ion in the env i ronm ent . Af ter

t h e en zy m e s to p s, r e s id u es a r e p r e s en t o n ly i n t h e p r im ar y s t ru cu t r e , w h i l e

there i s no c hem ica l r es idue s l ike ly to a f fec t the sk in . Bes ides , they wi l l no t

l eav e ch em ica l r e s id u es o n th e p r o ces s ed m a te r i a l s an d t h e co lo u r ch an g e

o n th e d y ed g o o d s i s m in im a l .

T h e d i s ad v an t ag es s ti ll u n s o lv ed i n t h e p r ac ti ca l ap p l i ca t io n o f t h e ce l l u la s e

t r ea tm en t a r e t h a t t h e ce l l u l a s e ca t a ly t i c r eac t i o n r a t e i s a f f ec t ed ap p r ec i ab ly n o t

o n ly b y p H an d t em p er a r tu r e , b u t a l s o b y co ex i s t i n g ch em ica l s s u ch a s d y es o rsur fac tan ts in the t r ea tment so lu t ion o r on the subs t r a te .

1 5.3 T r e a t m e n t o f C o t t o n w i th E n z y m e s

The co t ton f ib re has a s ing le b io log ica l ce l l. The layer s in the ce l l s t ruc tu res a re

f io m th e o u t s id e o f t h e f ib r e t o t h e i n s id e , cu t i c le , p r im a r y w a l l , s eco n d a r y w a l l ,

an d l u m en . T h es e l ay e r s a re d i f fe r en t s t r u c tu r a l l y an d ch em ica l l y . T h e p r im ar y an d

s eco n d a r y w a l l s h a v e d i f f e ren t d eg r ees o f c r y s t a ll i n i ty a s w e l l a s d i f f e r en t m o lecu --

l a r ch a in o r i en t a ti o n . T h e cu t i c l e , co m p o s e d o f w ax , p r o t e in s an d p ec l i n s , i s 2 . 5 %

o f t h e f i b re w e ig h t an d is am o r p h o u s . T h e p r im ar y w a l l is 2 .5 % o f t h e f i b re w e ig h t ,

h as a c r y s t a ll i n i t y i n d ex o f ab o u t 3 0% , an d is co m p o s e d o f ce l l u lo s e . T h e l u m en is

co m p o s ed o f p r o to p l a s m ic r e s id u es . Ad d i t i o n a l l y , s i ze s an d s o i li n g s a r e ad d ed t o

co t ton f ib res . The to ta l ma ter ia l a dde d to the f ib re i s up to 20% o f the f ib re weigh t .

T r ad i t i o n a l l y , t h e ab s o r b an cy o f co tt o n i s im p r o v ed b y a lk a l i n e s co u r in g an d w h i t e -

n es s i s im p r o v ed b y o x id a t i v e b l each in g . T h e i n t en s iv e b as i c r e s ea r ch cu r r en t l y

b e in g co n d u c t ed o p en s u p i n t e r e s ti n g p o s s ib i li t ie s f o r t h e u s e o f en zy m es f o r g en t l e

r em o v a l o f co t t o n ' s a t t en d en t m a te r i a l w i th o u t t h e h i t h e r to n eces s a r y u s e o f a lk a -l ie s an d o th e r d u b io u s e f f l u en t co n t en t .



4 2 6 Ap p l i ca t i o n o f B io t ech n o lo g y in t h e P r e - t r ea tm en t P r o ces s es o f T ex t i l e s

1 5 .3 .1 E n z y m a t i c d e s i z in g o f c o t t o n a n d s i l k f a b r i c s

M al t ex t r ac t w as u s ed o r ig in a l l y fo r t h e d es i z in g o f am y laceo u s s i ze s f r o m th efabr ic . Later , a round 1900, Dias tafor was found more ef f ic ien t fo r s ta rch des iz ing .

Rap id as es w er e i n t r o d u ced i n 1 91 9 an d cau s e t h e l i q u e f ac t i o n o f s t a r ch i n co m -

p o u n d s s o lu b l e i n w a te r . A t p r e s en t a v a r i e ty o f t h es e p r o d u c t s a r e av a i l ab l e co m -

m e r c i a l ly . T h e y a r e m a i n l y b a s e d o n a m y l o p e c t ic e n z y m e s . T h e s e e n z y m e s d o n o t

d am ag e t h e ce ll u lo s e . T h es e en z y m es a r e e f fec t i v e a t v a r io u s t em p er a tu r e s r an g in g

f r o m 2 0 to 1 1 5 ~ co v e r in g a ll m ean s o f ap p l i ca t i o n s [ 4 2 ]. N o w - a - d ay s s p ec i a l

a t t en ti o n i s p a id t o w ar d s t h e d ev e lo p m en t o f sim u l t an eo u s d es i z in g an d s co u r in g i n

a n a l k a li n e m e d i u m r e p l a c in g t w o - s t a g e p r o ce s s .

Deg u m m in g o f s i l k t o r em o v e t h e s e r i c in i s an im p o r t an t s t ep . So d a - as h an d

s u lp h id es u s ed i n co n v en t io n a l d eg u m m in g p r o ces s n o t o n ly r ed u ces t h e f ab r i c

s t r e n g t h b u t a l s o c a u s e s p o l l u t i o n p r o b l e m . E n z y m a t i c d e g u m m i n g o n t h e o t h e r

h an d , o f f e r s a v e r y s a f e an d s im p le m e th o d o f d eg u m m in g . Ap ar t f r o m s e r i c in t h e

s i lk f ab r ic a l s o co n t a in ab o u t 2 % o i l t o fac i l it a t e w eav in g . E n z y m es n o t o n ly d i s -

s o lv e t h e g u m m y p o r t i o n b u t a ls o d i s s o lv e t h e oi l a t t h e s am e t im e . T h e m e th o d o t

ap p l i ca t i o n i s e i t h e r co ld w a te r s o ak in g f o r 1 2 t o 1 6 h o r w ar m w a te r (5 0 - 5 5 ~s o ak in g f o r 3 t o 4 h w i th ap p r o p r i a t e en zy m e s o lu t i o n . T h e ap p l i ca t i o n o f s e r i n e

p r o t eas e (B ac to s o l S I ) co m b in ed w i th h y d r o g en p e r o x id e b l each in g i n t h e p r e s en ce

o f d e t e r g en t p r o v id es e f f ic i en t d es i z in g o f s e r ic in i n 1 h o u r [ 43 ] .

1 5 .3 .2 T h e u s e o f e n z y m e s in m e r c e r i z a t io n

T h e e f f ec t an d ac t io n o f en zy m es s eem s to b e v e r y l im i t ed b ecau s e o f th e s t ro n -

g e r co n d i t i o n s o f a lk a li o f m er ce r i z in g s t ren g th . E n zy m at i c h y d r o ly s i s is acce l e r -

a t ed w h en m er ce r i za t i o n i s ca r r i ed o u t w i th o u t t en s io n [44 ]. T h e g r ea t e r acces s ib i l -

i ty an d l o w e r c r y s t a l l in i t y o f ce l l u lo s e m er ce r i zed w i th o u t t en s io n is a d ec i s iv e

f ac to r i n t h e en zy m at i c h y d r o ly s i s p r o ces s . Mer ce r i zed co t t o n i s g en e r a l l y m o r e

p r o n e t o en zy m at i c m o d i f i ca t i o n t h an u n t r ea t ed co t to n .

1 5 .3 . 3 A p p l i c a t i o n o f e n z y m e s i n s c o u r i n g a n d b l e a c h i n g o f c o t t o n

T o ach i ev e g o o d ab s o r b an cy o f co tt o n , d i rt , si ze s an d n a tu r a l im p u r i t i e s a r e

u s u a l l y r em o v e d b y a lk a l in e s co u r in g . I f t h e s e im p u r i t ie s a r e n o t r em o v ed , can l ead

to t h e f o r m a t io n o f AOX in t h e e f f l u en t w h e n N aOC1 i s u s ed a s a b l each in g ag en t

[45] .E n z y m at i c t r ea tm e n t o f u n s co u r ed co t t o n fab r ic can b e d o n e w i th p ec t i n as e ,



A p p l i c a t io n o f B i o t e c h n o l o g y i n th e P r e - t r e a tm e n t P r o c e s se s o f T e x t i le s 4 2 7

c e l l u l a s e , p ro t e a s e , l i pa s e a nd o t he r e nz y m e s [ 46 ] . C e l l u l a s e s a r e e s pe c i a l l y s u i t e d

t o s c o u r i n g o f c o t t o n f a b r i cs [ 4 7] . T h e d e g r e e o f w h i t e n e s s o f a c o t to n s a m p l et r e a t e d w i t h c e l l u l a s e s o n l y i s l o w e r b y 8 - 1 0 % t h a n t h e d e g r e e o f w h i t e n e s s o t

a l k a l in e b o i l e d - o f f t r e a tm e n t . P e c ti n o l y t ic e n z y m e s c a n b e u s e d f o r e n z y m a t i c d e g -

r a d a t i o n o f p e c t i n a d h e r i n g t o c o t to n [ 4 8] . C o t t o n f ib r e s o r th e i r b l e n d s w i t h o t h e r

f ib r e s c a n b e t r e a t e d w i t h a q u e o u s s o l u t io n s c o n t a i n i n g p r o t o p e c t i n a s e s f o r 1 8 h a t

40 ~ t o g i ve s c oure d ya m s w i t h good te ns i l e s t r e ng t h r e t e n t i on [ 49 ]. Pe c t i na s e s a nd

c e l l u la s e s a r e v e r y e f f e c t i v e c o m p a r e d t o t h e p r o te a s e s a n d l ip a s e s [ 5 0] . T h e m o s t

s i gn i f i c a n t r e s u l t s o f va r i ous e nz yme s a r e l i s t e d i n Ta b l e 15 . 2 . The c ha nge i n t he

w a t e r a b s o r b a n c y o f c o t to n i s r a p i d l y c a t a l y s e d b y p e c t i n a s e s , c e l l u l a s e s o r t h e i r

T A B L E 1 5 . 2

S u m m a r y o f R e s u lt s a n d C o n d i t i o n s o f E n z y m a t i c T r e a t m e n t s f o r A d e q u a te

A b s o r b e n c y o f C o t t o n [ 5 0 ].

F ibre /Fab r ic C , C 2 C 3 P , P , P3

Fi b re

C o t t on w e i gh t , g 0 . 2 0 . 2 0 . 2 0 . 2 0 . 2 0 . 2

E n z y m e u n i t s - 4 0 3 0 4 4

C o nc e n t r a t i on , % 0. 1 0 . 44 0 . 0 23 0 . 0 25 0 . 0 0 6 7 0 . 0 0 17

T r e a t m e n t t i m e 1 0 m i n 1 0 m i n 1 0 m i n 2 h r 1 0 m i n 1 0 m i n

W e i g h t l o s s , % 3 . 9 0 0 2 . 26 6 3 . 0 44 2 . 57 1 1 . 6 42 1 . 8 9 8

Fa br i c

Fab r ic w e igh t , g 0 .4-0 .5 0 .5 0 .5 0 .4-0 .5 0 .5 0 .5

En z y m e un i t s - < 6 0 < 45 - < 16 < [ 6

C o n c e n t r a t i o n , % 0 . 1 5 - 0 . 2 < 0 . 6 6 < 0 . 0 3 4 5 0 .1 < 0 . 0 2 6 8 < 0.(~ 06 8

T r e a t m e n t t i m e 2 0 m i n 2 0 m i n 2 0 m i n 3 h r 2 0 m i n 21) m i n

N o t e 9C , , C 2 a nd C 3 ar e ce l lu las es , P , , P2 and P 3 a r e pe c t i na s e s .

m i x t u re s . Pe c t i na s e s c a n d e s t roy t he c u t i c le s t ruc t u r e by d i ge s t i ng t he i nne r l a ye r o !

pe c t i n s i n t he c u t i c l e o f c o t t on . C e l l u l a s e s c a n de s t roy t he c u t i c l e s t ruc t u r e by d i -

g e s t i n g t h e p r i m a r y w a l l c e ll u l o se i m m e d i a t e l y u n d e r t h e c u ti c le o f c o t to n . B y c o m -

b i n i n g t h e e n z y m e tr e a t m e n t (a s im u l t a n e o u s t r e a t m e n t o f p e c t i n a s e a n d c e l lu l a s e ),

o r t h e a l k a l i n e b o i le d - o f f , w i t h a n a l k a l in e p e r o x i d e b l e a c h i n g , t h e t o t a l d e g r e e o f

w h i t e n e s s i s h i g h e r i n c o m b i n a t i o n w i th e n z y m e t r e a tm e n t . C e l lu l a s e s b r e a k t h e



4 2 8 A p p l i c a t io n o f B i o t e c h n o l o g y i n t h e P r e - t r e a t m e n t P r o c e s s e s o f T e x t i l e s

l i n k a g e f r o m t h e c e l l u lo se s i d e a n d th e p e c t i n a se s b r e a k t h e l in k a g e f r o m t h e c u t i c le

s i d e. T h e r e su l t o f th e sy n e r g i sm i s a m o r e e f f e c t i v e s c o u r i n g i n b o t h t h e sp e e d a n dt h e e v e n n e s s o f t he t r e a tm e n t .

N a t u r a l p i g m e n t s p r e se n t i n c o t t o n a r e r e sp o n s i b l e f o r g r e y n e s s o f t h e su b s t r a te

b e f o r e b l e a c h i n g . M o t e s a r e s w o l l en i n a lk a l i n e s c o u r in g a n d r e m o v e d o r r e n d e r e d

c o l o u r l e s s i n o x i d a t i v e b l e a c h i n g . I n t h e Sy n b l e a c h p r o j e c t [ 5 1 ] n a t u r a l f i b r e s a r e

b l e a c h e d w i t h h y d r o g e n p e r o x i d e f o l l o w e d b y e n z y m e s , p h o t o s e n s i t i s e r s a n d U V

l ig h t . M e t h o d s o f b l e a c h i n g o f p a p e r p u l p a n d d e i n k i n g p r i n t in g p a p e r u s i n g e n -

z y m e s h a v e b e e n r e p o r t e d [ 5 2 ]. A f r i c t i o n t r e a t m e n t i s su g g e s t e d b e fo re ', t h e e n z y -

m a t i c t r e a t m e n t t o r e m o v e t h e p i g m e n t m o r e e a s i ly a n d e n s u r e t h a t c e l lu l a s e a n d

h e m i - c e l l u l a se a r e e f fe c t i v e [ 5 3 ].

T h e c e l l u l a se , x y l a n a se a n d p e c t i n a se e n z y m e s h a v e t r e m e n d o u s e f f e c t o n pro ...

c e s s i n g o f j u t e. T h e t r e a t m e n t o f e n z y m e b e f o r e b l e a c h i n g o f j u t e i m p r o v e w h i t e -

h e s s w h e r e a s d u e t o b a c k s t a i n i n g a t o p t i m u m p H , t h e r e i s d e c r e a s e i n w h i t e n e s s

a n d i n c r e a se i n y e l l o w n e ss i n d e x , i f t r e a t m e n t i s c a r r i e d o u t a f t e r b l e a c h i n g . T h e

e n z y m e a c t i o n is m o r e o n 4 % N a O H s c r o u r ed f a b ri c. S c o u r i n g c a u s e s h i g h e r h e m i -

c e l l u l o se l o s s p r o d u c i n g o p e n s t r u c t u r e a n d t h u s l a r g e r su r f a c e a r e a o f l i g n i n i sa c c e s s i b l e t o h y d r o g e n p e r o x i d e r e s u l t i n g i n h i g h e r w h i t e n e s s [ 5 4] .

15.3 .4 Bio-po l i shing

Su r f a c e m o d i f i c a t i o n o f c e l l u l o s i c f a b r i c s to i m p r o v e t h e i r c l e a n e r su r f a c e c o n -

f e r r i n g c o o l e r f e e l , b r i g h t e r l u m i n o s i t y o f c o l o u r s , so f t e r f e e l a n d m o r e r e s i s t a n c e

t o p i l l i n g u s i n g c e l l u l a se s i s o f t e n k n o w n a s b i o - p o l i sh i n g [ 5 5 , 5 6 ]. T h i s t r e a t m e n t

can be a pp l i e d to l~n it and w ov en ce l lu los i c f abr i c s su ch a s co t ton , v i sc~)se and

l i n e n a n d t h e i r b l e n d s [ 5 7 - 60 ] . T h e e l i m i n a t i o n o f su p e r f i c i a l m i c r o f i b r i l s o f t h e

c o t t o n f i b r e t h r o u g h t h e a c t i o n o f c e l l u l a se e n z y m e s i s o b t a i n e d b y t h e c o n t r o l l e d

h y d r o l y s i s o f c e l l u l o se l e a v i n g t h e su r f a c e o f th e f i b r e s fr e e a n d c o n f e r r i n g a m o r e

e v e n l o o k [ 61 - 63 ] . T h e e f f e c t o f c e l l u l a se e n z y m e s o n f a b r ic h a i r i n e s s is sh o w n in

F i g . 1 5 - 5 . T h e p i c t u r e o n t h e l e f t sh o ws a n u n t r e a t e d wo v e n 1 00% c o t t o n f a b r i c ,

wh i l e o n t h e r i g h t th e s a m e f a b r i c a p p e a r s a f t e r e n z y m e t r e a t m e n t . T h e se i m p r o v e -

m e n t i n f a b r i c so f t n e s s a n d sm o o t h n e s s a r e p e r m a n e n t i n c o n t r a s t t o t h e so f t e n e r s

a p p l i e d t o th e f i b r e su r f a c e . F u r t h e r t h e wa t e r r e g a i n i s n o t d e c r e a se d b y t h e e n z y -

m a t i c t r e a t m e n t [ 64 , 65 ] .A n u m b e r o f p a t e n t s a r e o b t a i n e d t o o b t a in s o f t en i n g e f f e ct b y e n z y m a t i c t r e at -



A p p l i c a t i o n o f B i o t e c h n o l o g y i n t h e P r e -t r e a tm e n t P r o c e s se s o f T e x t il e s 4 2 9

Figu re 15-5 . The ef fec t o f ce l lu lase on f abr ic ha i r iness .

m en t o f co t t o n t ex t i l e s [66- 71 ] . A l th o u g h b io - p o l i s h in g m ay b e ca r r i ed o u t a t an y

t ime du r ing we t p roce ss ing , i t i s m os t conv en ien t ly per fo rm ed af te r b leach i l lg . Fab-

r i c s m ay b e t r ea t ed i n e i t h e r p i ece o r g a r m en t f o r m an d t h e t r ea tm en t can b e co m -

b in ed w i th an o th e r p r o ces s o r k ep t a s a s i n g l e o p e r a t i o n . Ba t ch p r o ces s in g , u s in g

w a s h e r s , j e t s , b eck s an d w in ch es i s ex t r em e ly s u i t ab l e a s p H a n d t em p er a lu r e can

be con t ro l led eas i ly .

Co n t r o l l ed f i n i s h in g w i th ce l l u l a s e en zy m es o p t im i s es t h e s u r face p r o p e r t i e s o 1

th e f ab r ic , b u t d ec r eas e i n t en s i le s t r en g th [72 ]. Co m m er c i a l p r o ce s s es a im f o r 3-

6% w e ig h t l o s s a f t e r h y d r o ly s i s an d a r n ax im u m o f 1 0% lo s s in s t r en g th i s co n s id -

e r ed accep t ab l e [73, 70 ] . T h e s t r en g th / w e ig h t l o s s r e l a t io n s o f r em ie an d l i n en d if :

f e r f i o m th o s e o f co t t o n an d v i s co s e r ay o n [3 9] . T h e m ech an ica l p r o p e r t i e s b e f o r ean d a f t e r en zy m at i c h y d r o ly s i s o f d i f f e ren t f i b r e s a re co m p ar ed i n T ab l e 1 5 .3 . F ol

a ll the f ib res a f le r 6 ho urs ' t r ea tm ent there i s s ign i f ican t r educt ions in tens i le energy

(W T) and tens i le l inear i ty (LT ) , wh i le tens i le r es i l ienc e (R T) i s increas ed , ind ica t -

ing tha t the f ab r ics beco m e less s t if f, eas ie r to s t r e tch and loose r in s t ruc tu re . How -

ev e r , a f te r 4 8 h o u r s ' t r ea tm en t , s h e a r h y s t e r e s i s (2 HG ) v a lu es a r e m ar k ed ly l o w e l

th an t h o s e o f co n t r o l l s, i n d i ca t i n g y a r n s h av e b e co m e m o r e m o b i l e i n t h e l'ab ri c s.

An io n i c d y es s u ch a s d i r ec t an d r eac t i v e d y es an d ca t i o n i c a n d an io n i c s u r fac -

t an t s i n h ib it c e l l u l a s e ca t a ly t i c r eac t i o n ap p r ec i ab ly r e s u l t i n g i n d ec r eas ed w e ig h l

lo s s , w h e r eas n o n - io n i c d y es s u ch a s v a t d y es an d n o n - io n i c s u r f ac t an t s d o n o !



4 3 0 A p p l i c a t io n o f B i o t e c h n o l o g y i n t h e P r e - t r e a t m e n t P r o c e s s e s o f T e x t i l e s

T A B L E 1 5 . 3

C o m p a r i s o n o f M e c h a n i c a l P r o p e r ti e s o f C o t to n A f te r E n z y m e T r e a t m e n t [ 39 ].E n z y m e t r e a tm e n t fo r

Fa br i c 0 hou r s 6 hou r s 24 hou r s 48 hou r s

C o t t o n

W T, c m 2 4 . 8 6 3 . 47 3 .11 2 . 13

LT 0 .87 0 .77 0 .83 0 .78

R T, % 41 . 8 5 48 . 6 1 46 . 29 49 . 0 9

2 H G , g / c m 7 .0 4 7 .2 9 5 . 1 2 3 . 3 6

L i n e n

W T, c m 2 5 . 65 3 . 0 0 3 . 93 4 . 0 7

LT 0 .72 0 .66 0 .71 0 .69

R T , % 4 2 . 1 4 4 8 . 9 3 4 2 . 0 0 4 4 . 0 5

2H G , g / c m 0 . 83 1 . 02 0 . 56 0 . 29

R e m i e

W T , c m 2 5 .4 5 2 . 4 5 2 . 4 0 2 . 3 0

LT 0 .85 0 .63 0 .69 0 .73

R T , % 5 2 . 7 0 6 5 . 6 9 6 7 .8 7 6 8 . 7 6

2 H G , g / c m 4 . 5 9 4 . 1 6 3 . 8 4 3 . 3 6

C o t t o n / l i n e n ( w a r p )

W T, cm 2 1 .61 1 .02 1 .25 0 .84

LT 0 .81 0 .69 0 .72 0 .75

R T, % 44 . 8 7 50 . 27 57 .8 2 46 . 7 3

2H G , g / c m 1 .0 8 0 . 9 4 1 . 14 0 . 9 7

C o t t o n / l i n e n ( f i l l i n g )

W T, cm 2 2 .22 1 .96 1 .84 1 .51

LT 0 .85 0 .84 0 .86 0 .81

R T, % 56 . 39 51 . 24 58 . 7 2 57 . 9 8

2H G , g / c m 1 .0 8 0 . 9 4 1 . 14 0 . 9 7

s h o w r e m a r k a b l e i n h i b i ti o n [ 7 4 - 76 ] . T h e p l a n n e r s tr u c t u re o f v a t d y e s w i t h l a r g e r

mol e c u l a r s i z e s t ha n i nd i go dye p l a y a n i mpor t a n t r o l e i n t he i r i nh i b i t o ry , e f f e c t[ 7 7] . D M D H E U t r e a te d f a b r ic s h o w s a s l o w e r p r o g r e s s o f e n z y m a t i c c le a v a g e o n



A p p l i c a t i o n o f B i o t e c h n o l o g y i n th e P r e - t r e a tm e n t P r o c e s s es o f T e x t i le s 4 31

c r oss - l ink e d c e l lu lose . The de g r e e o f inh ib i t ion de pe n ds on c l a ss o f dye a nd dye

c onc e n t r a t ion . The inh ib i to r y e f f e c t m a y be due to the ion ic in t e r a c t ion be twe e nc e l lu l a se a nd a n ion ic dye s w i th su lphona te g r oups , t he c r os s - l ink ing a b i l i t y o f b i -

thnc t ion a l d ye s o r the l a r ge p l a nne r s t r uc tu r e o f va t dye s .

1 5 .3 . 5 E f f e e t o f c e l lu l a s e t r e a t m e n t i n w a s h i n g p r o c e s s e s

The r e a r e th r e e m e tho ds to r e m ove su r f a c e fib r e s f r om 10 0 % c o t ton wove n a nd

kn i t goods , na m e ly s inge ing in the g r e ige s t a te a nd b io - po l i sh ing . The th i r d m e thod

i s hom e l a u nde r ing the f a b r i c s u s ing de te r ge n t tha t c on ta ins a c e l lu l a se e nz y m e .

L a u nde r ing o f kn i t f a b r ic s w i th de te r ge n t c on ta in ing c e l lu l a se e nz y m e s he lp to

m a in ta in a c l e a n su r f a c e a ppe a r a nc e a nd the a ppe a r a nc e o f the f a b r ic look be t t e r

e ve n a f t e r m u l t ip l e l a unde r ings [7 8 ] . Toda y ' s de t e r ge n t s c on ta in a soph i s t i c a t e d

c o c k t a il o f e n z y m e s d e s i g n e d t o b r e a k d o w n s t ai n s a n d a s s is t t he c l e a n i n g p r o c e s s

a t l ow wa sh t e m pe r a tu r e . P r o te a se s , l i pa se s a nd a m yla se s a r e ge ne r a l ly u se d to

inc r e a se the e f f i c a c y o f r e m o va l o f s t ain s . C e l lu l a se s a s s i s t in the r e m o va l o f pa r-

t i c u la te so i l s by r e m o v ing m ic r o f ib r il f r om the c o t ton f ib r e s, wh ic h in i t i a lly f o r m

the p i l l s and w hic h sca t te r inc iden t l ight [79 , 80 ] . Ge nera l ly the de te rge nts for th is

pu r p ose r e ly on a m ix tu r e o f e nz ym e s , s t r ong se que s t r a n t s a nd so i l - re l e a se po ly -m e r s to p r ov ide sa t i s f a c to r y s t a in r e m o va l a n d so f t fin ish .

T h e s h o r t f i b r e e n d s e m e r g i n g f r o m t h e f a b r i c s u r f a c e i s e n z y m a t i c a l l y

h y d r o l y s e d , b u t a n a d d i t i o n a l m e c h a n i c a l t r e a tm e n t i s n e c e s s a r y t o c o m p l e t e t h e

p r oc e ss , t o r e m o ve the f ib r es no r m a l ly l e a d ing to p i ll i ng f o r e xa m ple , r o t a t ing d r um

wa she r s a nd j e t s [8 1 , 82 , 10 , 12 ] . I nc r e a s ing the de g r e e o f m e c ha n ic a l a g i t a tion

inc r e a se s the e x te n t o f t he hydr o lys i s [83 ] . P r io r m e c ha n ic a l a g i t a t ion m a ke s c e l lu -

lo s ic c ha ins m or e a c c e s s ib l e f o r c e l lu l a se hyd r o lys i s [8 4 ] . The c e l lu l a se t r e a tm e n t

a nd the f u r the r wa sh ing p r o c e ss show s im i l a r e ff e c ts t o tha t o f one s t ep p r oc e ss , bu t

w i t h s m a l l er c h a n g e s , w h i c h c o n f i r m s t h e r o le o f s i m u l t a n e o u s m e c h a n i c a l a g i t a-

t ion in c e l lu l a se t e x t i le p r oc e ss [8 5 ] . The c e l lob iohyd r o la se r i c h e nz ym e m ix tu r e s

p r odu c e m or e so lub le r e du c ing suga r s , w h ic h c a n a l so r e duc e the ind igo c lye a nd

inc r e a se ba c ks ta in ing . I n the two- s t e p p r oc e ss o f wa sh ing , t he to t a l l o s s o f c o lo u r i s

a bou t 20 %, wh i l e the one s t e p wa sh ing p r oc e ss y i e lds a lo s s o f c o lou r o f a bou t

40 %, und e r the sa m e c ond i t ions [ 10] .

1 5 .3 . 6 S t o n e w a s h i n gS tone a nd de n im wa sh e d ga r m e n t s , ge ne r a l ly c o tton , show a c ha r a c te r i st i c s we l l-



4 3 2 Ap p l i ca t i o n o f B io t ec h n o lo g y in t h e P r e - t r ea tm en t P r o ces s es o f T ex t i l e s

w o r n l o o k an d a r e v e r y p o p u la r w i th y o u n g p eo p le . In t h e s to n e w a s h in g p r o ces s ,

the f in i shed garm ents , wh ose f abr ic had been dyed w i th su lphur , o r r eac t ive dy es o rin d ig o a r e s u b j ec t t o t h e e r o d in g ac t io n o f p u m ice s to ne i n a w a s h in g m ach in e in

th e p r e s en c e o f an o x id i se r , u s u a ll y p o t a s s iu m p e r m a n g an a t e . T h e t r ea tm en t r e s u lt s

in une ven deco lou r i sa t ion , w i thou t excess ive loss o f f abr ic s t r eng th . The b lue den im

i s fad ed b y t h e ab r a s io n ac t io n o f p u m ice s to n es.

Ca t ion isa t ion o f the co t ton sur face by a t r ea tme nt wi th 1 , 1 -d im ethy l -3 -hydrox y-

a z e t i d i n iu m c h l o ri d e ( D M A - A C ) f o l l o w e d b y d y e i n g w i t h r e a c t iv e d y e s c a n d e -

v e lo p t h e a p p ea r an ce o f a d en im ty p e e f f ec t o n s p ec i a l ly co n s t r u c t ed f ab ri c [86] .

In t h e s am e w ay , w as h - o u t an d s to n e - w as h e f f ec t s can b e p r o d u ced o n d y ed

j ean s b y s u b j ec t i n g p i ece g o o d s t o a b io - f i n is h p r o ces s w i th s u i t ab le ce l l u la s e c o m -

p lex es w i th o u t p u m ice s to n e an d b l each in g ag en t s [72 , 87 ] . Co m p le t e o r p a r t i a l

r ep l ace m en t o f p u m ice s to nes b y ce ll u l a se en zy m es f o r t h e e f fec t o f s t o n e - w as h in g

o n d en im i s w e l l e s t ab l i s h ed an d h u n d r ed s o f l o o k s can b e g en e r a t ed t ' r ~m an y

p iece o f s t an d a r d d e n im f ab ri c [87 - 90 ]. T h e en zy m es o r co m b in a t i o n o f e l l zy m es

el imina te par t ia l ly p ro jec t ing dyed f ib res , expos ing the undyed m ater ia l unde rnea th .

T h i s f o r m s t h e u n ev en , co lo u r - f l eck ed s u r f ace o f w a s h - o u t a r t ic l e , b u t w i th n om a te r ia l s u r f ace d am ag e an d w i th an e l eg en t fab r ic ap p ea r an ce . T h e s u r f ace f ri c -

t i o n s p l ay an im p o r t an t r o l e i n t h e en zy m at i c d eco lo u r i s a t i o n o f ce l l u lo s ic f ab ri c s

[84] . T h e m ech an ica l ac t i o n o p en s t h e o u t e r m o s t l ay e r s o f t h e ce l lu lo s i c c r y s t a l ,

t h u s i n c r eas in g t h e p a r t o f t h e ce l lu lo s e a cces s ib l e t o en zy m es , an d a l l o w in g t h e

e n z y m a t i c r e m o v a l o f t h e d y e.

T h e u s e o f ac id ce l l u la s e s a r e r eco m m en d ed f o r f a s t t r ea tm en t s an d n eu t r a l ce l-

lu lases fo r m ore severe t r ea tments wh en m arke d ef fec t s a re r equ i red [56, 91 ] . Endo-

enr ich ed ac id ce l lu lase i s found to be bes t fo r eas i ly wee ken ed f abr ics such as l inen

an d v i s co s e r ay o n . S t an d a r d w h o le ac id ce l l u l a s e s a r e b es t f o r s t u rd y f ab ri c s s u ch

as l y o ce l l , m o d a l r ay o n an d h eav y w e ig h t co t t o n [92 ] .

1 5.4 T r e a t m e n t o f P r o t e in F i b r es w i t h E n z y m e

E n zy m at i c p r e - t r ea tm en t s t o p r o t e in f i b re s a r e g en e r a l l y co n cen t r a t ed o n w o o l

an d s i l k . It is p o s s ib le t o r em o v e s k in r e s id u es , s k in g r eas e an d v e g e t ab l e m a t t e r o t

w o o l b y en zy m at i c d eg r ad a t i o n m e th o d . F u r th e r m o r e , t h e w o o l s u r f ace can b e

m odi f ied , and f e lt fr ee f in i sh ing wi th s imul taneous imp rovem ent o f lus tr e and hand leo f w o o l l en f ab ri c i s p o s s ib l e b y en zy m e t r ea tm en t .



A p p l i c a t i o n o f B i o t e c h n o l o g y i n t h e P r e -t r e a tm e n t P r o c e s s e s o f T e x t i le s 4 3 3

Th e two m a jo r m or ph o log ic a l pa r t s in the s t ruc tu r e o f wo o l a r e c u t ic l e a nd

cor tex . Th e epi -cu t ic le of wo ol f ibres sur round s each cut ic le , it con s is ts of approxi -m a te ly on e - qua r t e r f a t ty a c id and th r e e - qua r t e rs p r o te in by m a ss . T he hyd r opho b ic

e p ic u t i c l e a c t s a s a ba r r ie r t o dye s w h ic h e n te r t he woo l f ib r e be twe e n c u t i c l e c e ll s

t h r o u g h t h e h i g h l y c r o s s - li n k e d c e ll m e m b r a n e c o m p l e x ( C M C ) . E n z y m e f ro m t h e

l iquor can d i f fuse in to the in te r ior of the f ibre and hydro lyse pa r ts o f the endo cut ic le

a n d p r o t e in s i n th e c e l l m e m b r a n e c o m p l e x , c o m p l e t e ly d a m a g i n g t h e f ib r e i f n o t

c on t r o l l e d . I n c on t r a s t , t he c a t a ly t i c a c t ion o f e nz ym e on c o t ton i s c on f ine d to the

su r f a c e a nd the a m o r pho us r e g ion on ly .

En z ym e s suc h a s p r o te a se s , l i pa se s , li popr o te in l i pa se s a nd p r o te o ly t i c e n z ym e

de r ive d f r om the ba c te r ium S t r e p tom yc e s f r a d ie ( know n a s S FP) i s c a pa b le o f a t-

t a c k ing na tu r al ke r a t in hyd r o lys ing som e pe p t ide l i nka ge s . How e ve r , p r o te a se s a r c

m o s t w i d e l y u s e d .

1 5 .4 .1 W o o l c a r b o n i s i n g

V e g e t a b l e m a t te r s o f w o o l a re n o r m a l l y r e m o v e d b y a p ro c e s s k n o w n a s

c a r b o n is i n g . C a r b o n i s a t i o n o f w o o l w i t h i n o r g a n ic a c i d m a y c a u s e s o m e d e g r a d a -

t io n o f t h e f ib r e. T h e r e p l a c e m e n t o f c a r b o n i s a t i o n b y t h e u s e o f e n z y m e s , s u c h a sc e l lu l a se s , l ign ina se s , hyd r o la se s , l ya se s a nd ox ido r e duc ta se s a r e re por t e d [93 ] . A

b i o c h e m i c a l a l t e rn a t iv e u s i n g c o m p l e x c o m b i n a t io n o f e n z y m e s t o t h e c h e m i c a l

p r oc e ss o f c a r bon i s ing wi th su lphur i c a c id i s a l so r e por t e d [9 4 ] . The a m oun t o l

su lphur i c a c id r e qu i r e d f o r c a r bon i sa t ion c a n be r e duc e d by the a c t ion o f c e l lu -

lo ly ti r a nd pe c t ino ly t i c e nz ym e s [9 5 ] .

Na tu r a l so i l ings on woo l suc h a s ve ge ta b le m a t t e r a nd sk in f l a ke s c a n a l so be

e n z y m a t i c a l ly m o d i f i e d [ 96 ]. B u r r r e m o v a l b e c o m e s e a s ie r a f te r l u b r ic a t in g w o o l

wi th c e l lu l a se s due to we a k e n ing o f the c ohe s ion be tw e e n bu r r a nd w oo l [97 ].

L ign in o f the bu r r s in wo o l c a n be de g r a de d by the use o f l ig n in pe r o x ida s c s [98 ].

1 5 . 4 . 2 W o o l b l e a c h i n g

B l e a c h i n g o f w o o l i s n e c e s s a r y f o r th e e n h a n c e m e n t o f w h i t e n e s s a n d l u st re .

Us ing p r o te o ly t i c e nz ym e s a lone [9 9 ] o r i n c om bina t ion wi th pe r ox ide [10 0 ] , t he

de gr e e o f w h i t e ne ss a n d hydr op h i l i c i ty o f t he f ib r e s a re inc r e a se d , c om pa r e d wi th

the ox ida t ive t r e a tm e n t a lone [9 9] . S e r ine p r o te a se s t a b le to hyd r oge n p e r ox ide is

a c t ive in a n a lka l ine m e d ium a nd i t s a c t iv i ty inc r e a se s w i th inc r e a s ing pe r ox idele ve l [9 4 ] . H igh e r w h i t e ne ss inde x i s c a use d b y the de c o lou r i s ing a c t ion ot" the

e nz y m e on na tu r a l c o lo r a n t s p r e se n t i n the woo l f ib r e [10 0 ].



4 3 4 A p p l i c a t i o n o f B i o t e c h n o l o g y i n t h e P r e- t re a t m e n t P r o c e s s e s o f T e x t i le s

1 5 .4 .3 S h r i n k p r o o f i n g a n d h a n d m o d i f i c a t i o n o f w o o l

W ool f ib re s ha ve a t e nde nc y to f e l t and sh r ink due to i ts s c a ly s t ruc tu r e . Thed i f f e r e n t i a l f r i c tiona l e f f e c t (DFE ) c a use s the f ib r e to m ove towa r ds the i r roo t e nd

w he n m e c ha n ic a l a c t ion i s a pp l i e d in the we t s t a te . Ge ne r a l ly sh r ink ing o f woo l is

don e e i the r by ox ida t ive o r r e duc t ive m e thod s a nd /o r by a pp l i c a t ion o f r e s in . The

m o s t f r e q u e n t l y u s e d c o m m e r c i a l p r o c e s s c o n s i s t s o f ch l o r in a t io n , f o l lo w e d b y

d e c h l o r i n a t i o n a n d p o l y m e r a p p l i c a t i o n . A m o n g t h e v a r i o u s p r o c e s s e s , n i c k e l -

c a t a l y s e d s u r f ac e d e g r a d a t i o n b y h y p o c h l o r i t e [ 1 0 1- 1 03 ] a n d t h e u se o f ' s e c o n d

g e n e r a t i o n ' c h l o r i n a t i o n e q u i p m e n t [ 1 0 4 ] a r e c o m m e r c i a l i s e d . T h o u g h s u c h

d e s c a l i n g i s e x p e c t e d t o i m p r o v e t h e h a n d l e o f th e w o o l f ib r es b y m a k i n g t h e m

sm o othe r , t he ha nd le i s a c tua l ly m a de ha r she r , pe r ha ps be c a use the f ib re s be c om e

s iz e d by de g r a de d p r o te in . Ho we v e r , t he so f tne s s o f t he f ab r i c c a n be im pr ove d a s

a f ina l a pp l i c a t ion o f a s i li c one m ic r oe m uls ion [ 105 ] , bu t e xpe ns ive e qu ipm e n t a r e

ne e de d .

I t is poss ib l e to l im i t c h lo r ina t ion a nd o the r ox ida t ions to the c u t i c l e l a ye r to

rem ov e the f ibre f rom the surfac ,e o f the f a b r i c w i thou t d a m a g ing the f ib re a nd thus

inc reases i t s sof tness too . Conseq uent ly , in addi t ion to the ant i fe lt ing e f fec t achievedby the p r e t r e a tm e n t a nd p r oc e ss in g o f wo o l f ib r e s , a so f t ha nd le i s a l so ob ta ine d .

Of a l l t he e nz ym e p r oc e sse s a va i l a b le f o r woo l , on ly a f e w a r e ' pu r e ' e nz ym a t i c

p r oc e sse s . The m a jo r i ty o f e nz ym a t i c p r oc e sse s pub l i she d a re c om bine d p r oc e sse s.

I n m os t o f the t r e a tm e n t s f o r im p r ov ing the ha nd le o f woo l , r e duc t ion o f the f ib r e

d ia m e r t e r i s done by c o m p le te de sc a l ing wh ic h p r oduc e a non- to l e r a b le w e igh t lo s s

o f the f ib re s . De s c a l ing i s ge ne r a l ly pe r f o r m e d b y p r e t r e a t ing the f ib re s w i th po ta s -

s i u m p e r m a n g a n a t e a s a p r e o x i d i s i n g a g e n t [ 1 0 6 ] o r b y g a s c h l o r i n a t i o n ( t h e

C h lo r z ym p r oc e ss [ 10 7] ) o r by hy dr og e n pe r ox ide ( the Pe r z ym p r oc e ss [ 10 8] ) a nd

subse que n t t r e a tm e n t w i th a p r o te o ly t i c e nz ym e [10 9 ] . Thus i t i s poss ib l e to r e -

m ove the sc a l e s by us ing m uc h l e s s tha n 5% c h lo r ine i f t he p r oc e ss i s fo l lowe d by

a n e n z y m e .

Pr o te a se , t r yps in o r pa pa in a r e c om m only use d a s e nz ym e s f o r woo l f ib r e s .

Protease i s qui te unreac t ive unless ac ted upo n by a mi ld reduc ing agent , i . e . b isu lphi tc

o r c ys t e ine , so a s to sp l i t d i su lph ide to su lphydr y l g r oups [110 - 113] . O the r e n -

z ym e s h a ve be e n p r op ose d [ 114, 115 ], i nc lud ing ba c te r i a l a lka line p r o te a se s o f t hetype use d in wa sh ing powde r s . I n som e p r oc e sse s p r o te a se s a r e u se d to c u t - o f f

da m ag ed f ibres [ 116] or to achiev e c e r ta in tex tur is ing e f fec ts [ 117 , 1181].



A p p l i c a t i o n o f B i o t e c h n o l o g y i n t h e P r e -t r e a tm e n t P r o c e s s e s o f T e x t i le s 4 3 5

De sc a l ing i s a lso a c h ie v e d by the a pp l i c a i ton o f he a t - r e s i s ta n t ne u t r a l p r o te a se ,

r e su l t ing in c a shm e r e - l ike f e el [ 119] . The c om bine d use o f the c h lo r ina t ing a ge n t ,

d i c h l o r o i s o c y a n u r a t e a n d p r o t e o ly t i c e n z y m e c a n i m p r o v e h a n d l e p r o p e r t ie s [ 1 20 ,

121].

Phys ic a l , a s we l l a s c he m ic a l , p r e t r e a tm e n t p r oc e sse s ha ve be e n c om bine d wi th

the e nz ym e t r e a tm e n t o f woo l . A low - te m p e r a tu r e p l a sm a i s a pp l i e d to the f ib r e s

p r i o r to t r e a t m e n t w i t h p o l y m e r i c s h r i n k p r o o f i n g a g e n t [ 1 22 ]. C o m b i n e d p r o t e a se

a nd he a t t r e a tm e n t w i th a s a tu r a t e d s te a m [123 ] a nd the use o f h igh f r e que nc y

r a d ia t ion on e n z ym e t r e a t e d m a te r i a l s a r e r e por t e d .

1 S.S B i o - te e h n o l o g y a n d E f f lu e n t T r e a t m e n t

En vi r on m e n t f r ie nd ly p r e - t r e a tm e n t p r oc e sse s o f t e x t il e s a r e the ne e d o f the da y

d u e t o t re m e n d o u s a w a r e n e s s o f c h e m i c a l p o l l u ti o n a n d m o u n t i n g l e g i sl a ti o n t o

l im i t t he c he m ic a l bu r de n o f the f a c to r y e f f lue n t . B io te c hn o logy c a n be u se d f o r the

t r e a tm e n t o f wa s te s wh ic h c a n so lve the p r ob le m e i the r pa r t i a l ly o r t o t a l ly . The

a pp l i c a i ton o f b io te c hn o lo gy i s m a in ly a t t ribu te d to the re m ova l o f c o lou r f r om the

dye h ouse e f f lue n t s . L iv ing o r ga n i sm s i s u se d to b ind a nd de g r a de c o lou r ( e .g . a r ti -

f icia l r eed beds) or dead organ ism s (e .g . s t raw, ch i t in /chi tosan , mic ro fung a l hy phaee tc. ). S e le c t e d m ic r o be s o r i so l a t e d e nz ym e m a y be u se d to a s s i s t spe c i f ic a r e a s .

The d i sc ha r ge o f dye s tu f f s i n to the e nv i r onm e n t i s no t so l e ly a n a e s the t i c m a t t e r

a nd m a ny dye s tu f f s a r e ide n t i fi e d to be m uta ge n ic [ 123] . B ioso r p t ion ha s the po -

t e n t ia l t o r e m ov e m e ta l i ons suc h a s c h r om ium [ 124 ] , w h ic h a r e u se d in the m a nu-

f a c tu r e a n d a p p l i c a ti o n o f m o r d a n t d y e s . T h e e n z y m a t i c b l e a c h i n g o f r e l e a s e d d y e

r e d u c e s p r o c e s s t i m e a n d t h e a m o u n t o f e n e r g y a n d w a t e r n e e d e d t o a c h i e v e a

sa t i s f a c to r y t e x t i le qua l i ty [ 125 ]. How e ve r , t he type a nd the c o nc e n t r a t ion o f dye s

a s we l l a s the a m oun t a nd type o f subs t r a t e u se d a r e f ound to p l a y a m a jo r r o l e in

dye a dso r p t ion [ 126, 127] . C h i tosa n is f ound to be m os t e f f i c i e n t i n a bso r b ing dy e s

o f sm a l l m o le c u la r s i z e [128] .



4 3 6 A p p l i ca t i o n o f B i o t ech n o l o g y i n t h e P re - t r ea t men t P ro ces se s o f T ex t i l e s

R E F E R E N C E S

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31 O. Tan ida , Sen sho ku-K ogy o, 37 (1989) 122.

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33 V .P . Pur i , B io tech nol . Bioeng. , 26 (1984) 1219.

34 J . Schu rz and A.Ho nel , Cel lu lose Chem . Tech nol . , 23 (1989) 465.35 H. Es terba uer an d A. Janosi , Das Papier , 38 (1984) 599.

36 D. Ber t r and and A. Bu leon , Co l loque Ce l lu lo lyse Microb i enne , CN RS

Marsei l l e , France (1980) 127.

37 M. M. C hang and G. T. Tsao , Paper presented a t the 16 l th A CS M eet ing ,

Atlanta, 1981.

38 J . Len z et al. , J . App l . Polym . Sci . , 41 (1990) 1315.

39 G. Bu sch le-D il ler et al. , Te xt i le Res. J. , 64 (5) (1994) 270.

40 J . Sch urz et al ., Ac ta Poly m . , 36 (1985) 76.

41 Y. Ura gam i , G. L . W eiss and E. A. Larenas , PCT In t . Appl . W O 9206 183.

42 Tec hnica l inform at ion on des iz ing (No vo No rdisk , 1992).

43 S . Fornel l i , Ma gic enzym es (Sando z SA).

44 G. Bu chle-D i l ler and H. Z . Ze ronian , Text i le Che m. Co lor . , 26 (1994) 17.

45 G. Schulz, Text i l Prax is , 1 (1990) 40.

46 U. Rohne r , Mel l iand T ext i lber ., 74 (2) (Feb 1993) E 63 .

47 U. Ro sner , Mel l iand Text i lber . , 74 (1993) 144.48 E. Ba ch and E. Scho l lmey er , Tex t i lvered lung, 27 (1) (1992) 2 .



4 3 8 A p p l i ca t i o n o f B i o t ech n o l o g y i n th e P re - t r ea tme n t P ro ces se s o f T ex t i le s

49 T . Sakai and A. Ma suda , Japan ese Pa ten t No . 06220772 , Aug . 9 , 1994 .

50 Yo ngh ua Li and I. R. Hard in , Tex t i l e Chem . Color . , (Aug 1997) 71 .51 An nua l Re por t (Be lg ium : Con texbel , 1993) .

52 Ch em . W eek , (10 June 1992).

53 C. Z eyer , Am er . Dye s tu f f Rep . , 26 (1994) 26 .

54 S .N . C hat top adh yay e t a l ., In t. Sem inar on Ju te and Al l i ed F ibres , Organ i sed

b y N IRJ A F T & In d i an F i b re S o c i e t y (1 998) p 2 2 2 .

55 H. Kawamura and I . Wakkida , Bul l . Appare l Sc i . Res . Cen t re , Koyto Ins t .

Tec hnol , no . 8 (1989) 99 .

56 D. Koc hav i , I. Videb ack and D. M. Cedron i , Ame r . Dy es tu f f Rep . , 79 (21

(1990) 24.

57 L. O . A sferg and T . Videba ck , In t. Tex i le Bul l . , Dyg . /P tg . /F ing . , 36 (1990) 5 .

58 W . H. He m m pel , In t . Tex t i l e Bul l ., Dyg . /P tg . /F ing . , 37 (1991) 5 .

59 J . Ro binson , In t . Tex t i l e Bul l ., Dyg . /P tg . /F ing . , 2 (1994) 5 .

60 I . Videba ck, M . Fich and G. Screws, Int . Text i le Bul l. , Dyg./Ptg. /Fing. , 1 (1994)

40.

61 U. Hotz , Ten s ide Sur fDe ter . , 30 (1993) 388 .62 G. I . Pedersen ; G. A. Screws and D. M. Cedron i , Mel l i and Tex t i lber . , 12

(1993) 1277.

63 L. G. Snyder , Tex t i l e Ch em . Color . 29 (June 1997) 27 .

64 G. I . Pede rsen, G. A. Screw s and D. M. Cedro ni , L' Industr ie Text i le , 6 ( 1993 )

53.

65 G. I . Pedersen , G. A. Screw s and D. M. Cedron i , Tex t i le As ia , 24 (12) ( 1993 t

50.

66 I t . R . Browning , German P 2148 278.

67 Ku rash ik i Sp inn ing Co . , Japane se P 58054082 .

68 M. Yam agish i , Ka ko Gi ju t su (Osaka) , 23 (3) (1988) 6.

69 Y. Ura gam i and I . Tana ka , Japanese P 02169775 .

70 G. I. Ped ersen , G. A. Screw s, D. M. C edro ni , Can. T ext i le J . , 109 ( l 0) (1992 )

31.

71 T . Vid eba ck and I. D . And ersen , PC T In t . Appl . W 09320 278.

72 R. M. Tyn dal l , Tex t i l e Ch em . Color . , 24 (6) (1992) 23 .73 Anon . , Co t ton Grow er , 27 (1991) 20 .



Ap p l i ca t io n o f B io tech n o lo g y in th e P r e - t r ea tm en t P r o cesse s o f Tex t i le s 4 3 9

74 H. Koo e t a l ., Texti le Re s. , J. , 64 (1994) 70.

75 R. Mori . , I. Ha ga an d I. Ta kagis hi , J . Appl. Polym . Sci , 45 (1992) 1869.76 M. Ued a et a l ., Sen-I Gakkaish i , 50 (11) (1994) 554.

77 E. K. Ch oe et a l. , Tex ti le Res. J ., 67 (1997) 1 55.

78 S. Sn yder , Te xti le Chem . Co lor . , (June 1997) 27.

79 P . Lay m ann , Chem . Eng . Ne ws, 18 (1990) 17 .

80 S .G . M ay cu m b er , P & G De te r g en t Dev e lo p m en t ch ee red o n b y Co t to n In c .,

Dai ly N ew s R ec . , no . 2 (1993) 2 .

81 A. Ca vaco -Paulo and L. Alm eida , Bioc a ta lys ts , 10 (1994) 353.

82 A. Cav aco -Pau lo and L. Alm eida, J . Tex ti le Inst . , 87 (1) (1996) 227.

83 A. Ca vaco-Pau lo , L. Alme ida and D. Bishop , Proc . 77th Tex t i le Ins t . Conf . ,

Tempere, Vol. 2 (1996) 269.

84 C. Zeyer , J. Rucker , T . Joyce and J . Hei tm ann , Tex t i le Che m. C olor ., 26 (3)

(1994) 26.

85 A. C ava co-P aulo , J. C oretz and L. Alm eida, J. Soc. Dy ers Colou rists , 113

(1997) 218.

86 S . R . K arm aka r and M. Dat ta , J . Tex t i le Assocn . , (March 1994) 291 .87 T . Olson , Amer . Dy estu f fR ep . , 77 (5) (1988) 19 .

88 S. Klaho rst , A. Ku m ar and M. M. M ull ins, Tex ti le Chem . Color . , 26 (2) (1994)

13.

89 D . McE wan , M. Y . Yo o n an d S . R . Lasco , Bo o k o f P ap e r s, AATC C Gar m en t

W et P r o cess in g Tech n o lo g y Sy m p o s ia , Mar ch 1 995.

90 R .M . Ty n d a l l, Bo o k o f P ap e rs , AAT CC G ar m en t W e t P r o cess in g Sy m p o s ia ,

1993.

91 S. Eh ret , Dye r , 7 (1994) 27.

92 A. Ku m ar , M.Y. Yo on and C. Pur te l l, Tex t i le Chem . Color , 29 (4) (1997) 37 .

93 R . Saw ick a - Zu k o w sk a an d A . Zak r zewsk i , P o li sh P 1 4 74 98.

94 S . Forne l l i , Ma gic enzym es (Sando z SA).

95 N . Sed e ln ik , L . La tk o w sk a an d R . Sawick a - Z u k o w sk a , Ge r m an P 3 54 3 5 01 .

96 M. C. Brah imi-Hom, M. L. Gugl ie lmino , A. M. Gaal and L. G. Spar row,

Proc. 8th Wool Text . Res. Conf . , Vol. 3 (1990) 195.

97 Zu P in Rong and Zhou J ing Hua , Proc . 8 th Wool Tex t . Res . Conf . , Vol . 3(1990) 195.



440 App l i ca t i on o f B io t echno logy i n the P re - t rea tmen t P roces ses o f Tex t i le s

98 M. Lieb eskind , H. H~cker , C . W and rey and A. G. Jaeger, FE M S M icrobio l .

Lett . , 71 (1990) 325.

99 S . Fom el l i , Tex t i lvered lung, 27 (1992) 308.

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Me et ing , Me w Delh i (Mar 1994).

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104 IW S technical informa t ion bul le t ins AP 91 and 163.

105 IW S Produc t inform at ion bul le t ins AP 168 and 169.

106 Ku rashik i Spinning Co., Japanese P 58144105.

107 W oo l Sci. R ev., 18 (196 0) 18.

108 H. G. Otten an d G. B lank en bu rg, Z. Ges. Tex t i l ind, 64 (1962) 506.

109 T. Kon do, C . Sakai and T. Kara kaw a, Euro pean P 134267.

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116 A. Ben esch , Germ an P 2123607.

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118 A. W iedem ann , Germ an P 4226162 .

119 An on. , Text . Horizon s, 4 (5) (1992 ) 7.

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122 T. Na kan ish i and K. Iwasak i , Japane se P 04327274.

123 I . Jag er et al ., M ell ian d Tex t i lber. , 77 (1996) 72.

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126 B. M. Youssef , Am er . Dy es tu ffR ep . , 82 (1993) 36.

127 J . A. Lasz io, Ame r. D ye stu ff Re p. , 83 (1994) 17.128 B. Sm i th e t a l ., Am er . Dy es tu ff Rep. , 82 (1993) 18.



Chapter 16

A N A L Y S I S A N D T E S T I N G I N P R E P A R A T O R Y P R O C E S S E S

1 6.1 I n t r o d u c t i o nTh e ob je c t ive o f c he m ic a l p r e - t r e a tm e n t o f t e x t i le s i s t o ob ta in un i f o r m e f f e c ts

a s r e ga r ds to s i ze r e m ov a l , a bso r b a nc y , w h i t e ne ss , a bse n c e o f husks , d ye a f f in ity ;

h i g h d e p e n d e n c y o f r e s u lt s ; m i n i m u m f ib r e d a m a g e a n d f a v o u r a b l e c o s t p e r f o r-

m a nc e r e l a t ionsh ip . The f a c to r s w h ic h a f f e c t t he p r e - t r e a tm e n t a r e goods ( p r in t e d

or dye d) , m a c h ine r y , d i sp e ns ing sys t e m , de p e nda b i l i t y o f r e su l t s , e nd use, c us -

tom e r r e qu i r e m e n t s , e c onom ic a l a nd e c o log ic a l a spe c t s e t c . The po te n t i a l de f e c t s

d u r i n g p r e - t r e a tm e n t p r o c e s s e s a r e i n a d e q u a t e o r u n e v e n d e s i z in g , i n c o m p l e t e r e -

m o v a l o f g r ea s e s a n d w a x , p o o r o r u n e v e n a b s o r b a n c y , u n l e v e l m e r c e r iz a t i o n , i n -

a de qu a te o r uns t a b le g r ound w h i t e , poo r m e c h a n ic a l s t r e ng th , l ow DP va lue , c a ta -

ly t ic da m a ge a nd c r e a se s e tc . I n the c a se o f syn the t i c s tha t a r e he a v i ly o i l e d p r io r t o

o r du r ing kn i t ti ng , d ye spo t s a nd sp e c k ine s s l a te r a t tr ibu te to poor dye ing p r a c ti c e s .

I m p r o p e r s i ze r e m o v a l i s t h e m a j o r c a u s e o f u n l e v e l n e s s e n c o u n t e r e d i n th e r m o s o l

o r r a n g e - d y e d g o o d s .

I t i s t hus ne c e s sa r y to op t im ise the e f f e c ts o f va r ious p r e - t r e a tm e n t c he m ic a l s ,

focus ing on fabr ic phys ica l prop er t ie s such as tens i le s t rength , we ight loss , fuzz ing ,h a n d , c o p p e r n u m b e r , m o i s t u r e r eg a i n a n d c o l o u r c h a n g e ( in t h e c a s e o f d y e d f a b-

rics).

T h i s c h a p t e r i s d e v o t e d t o e v a l u a t e t h e u s e f u ln e s s o f m e a s u r e m e n t o f d i ff e re n t

phy s ic a l a nd c he m ic a l p r ope r t i e s o f t e x t i le f ib r e s be f o r e a nd a f t e r c he m c ia l p r e -

t r e a tm e n t to p r ov ide a d i r e c t a s se s sm e n t o f e f f e c t s o f d i f f e r e n t c he m ic a l s . S uc h

in f o r m a t ion a b ou t a p r ope r ty tha t i s im m e d ia t e ly a nd d i r e c t ly a f fe c t e d by c he m ic a l

r e a c t ion wi l l he lp to op t im ise the p r oc e ss c ond i t ions , whe r e by the de s i r e d e f f e c t s

c a n b e a c h i e v e d w h i l e m i n i m i s i n g t h e u n d e s i r e d e f fe c ts s u c h a s e x c e s s i v e s t re n g t h

loss e tc .

1 6 .2 A n a l y s i s o f W a t e r

To c a lc u la t e the ha r dne ss o f a pa r t i c u la r wa te r the c on c e n t r a t ion o f a c tua l m a g-

n e s i u m o r c a l c i u m s a lt is c o n v e r t e d t o a n e q u i v a l e n t w e i g h t o f c a lc i u m c a r b o n a te .

Ha r dn e ss i s ge ne r a l ly e xp r e s se d a s e qu iva le n t pa r ts pe r m i l l i on ( p .p .m . ) o f c a l c ium

c a r bon a te i r r e spe c t ive o f the a c tua l s a lt p r e se n t . B y de f ina t ion , 1o E n g l i s h h a r d n e s s



4 4 2 A n a l y s i s a n d T e s t i n g i n P r e p a r a to r y P r o c e s s e s

17i s 1 0 m g o f C a C O 3 i n 0 . 71 a n d 1 7 m g p e r 0 .7 1 = ~ = 1 . 7 ~ E n g l i s h h a r d n e s s .

10 24

S i m i l a r l y 1o U S h a r d n e s s i s 1 m g /1 o f C a C O 3 a n d s o 2 4 m g / 1 - - 2 4 ~ U S h a r d -1n e s s .

1 6 . 2 . 1 S u s p e n d e d m a t t e r

2 li t re s o f w a t e r a r e f il t e r e d t h r o u g h p r e v i o u s l y w e i g h e d f i lt e r p a p e r . T h e r e s i -

d u e i s d r i e d a n d w e i g h e d ( x g ). T h e r e s u l t s a r e e x p r e s s e d a s

x x l 0 6p . p . m . =

103

1 6 . 2 . 2 T o t a l s o l u b l e s a l tsF i r s t o f a ll t he d i rt a n d s u s p e n d e d m a t e r i a l s a r e r e m o v e d f r o m t h e s a m p l e w a t e r

a s d e s c r i b e d a b o v e . 2 5 0 m l o f t h i s w a t e r i s p u t o n d r i e d p l a t i n u m d i s h a n d h e a t e d

o n i r o n p la t e . T h e d i s h i s t h e n t r a n s f e r r e d o n a h o t w a t e r b a t h w h e n s o m e q u a n t i t y

o f w a t e r r e m a i n s i n t h e d is h . F i n a l l y , th e c o n t e n t i s d r i e d to c o n s t a n t w e i g h t i n t h e

o v e n , c o o l e d i n a d e s c i c c a t o r a n d w i g h e d ( x g) . T h e r e s u l t s a r e e x p r e s s e d a s

x x l 0 6 x 4p . p . m . =

1 0 3 x l

1 6 .2 .3 T o t a l h a r d n e s s

T h e t o ta l h a r d n e s s o f w a t e r c an b e d e t e r m i n e d e i t h e r b y u s i n g s t a n d a r d s o a p

s o l u ti o n o r b y u s i n g E D T A r e a g e n t.

I n th e f i r s t m e t h o d , 1 0 0 m l o f w a t e r i s p l a c e d i n a 2 00 m l s t o p p e r e d f l as k . 1 m l

o f s t a n d a r d W a n k l y n ' s s o a p s o l u t i o n i s a d d e d a t a t i m e u n t i l a l a t h e r i s o b t a i n e d o n

s h a k i n g w h i c h p e r s i s t s f o r o n e m i n u t e . I f t h e ti tr e o n 1 0 0 m l o f w a t e r i s T m l , s i n c e

1 .0 m l o f s ta n d a r d s o a p s o l u t i o n - 1 .0 g C a C O 3 .

... 1 0 0 p a r t s o f w a t e r c o n t a i n 0 . 0 0 1 T p a r t s o f C a C O 3

a n d 1 , 0 0 0 , 0 0 0 p a r ts o f w a t e r c o n t a i n 1 0 T p a r t s o f C a C O 3 .

... T o t a l h a r d n e s s = 1 0 T p . p . m , a s C a C O 3 .

I n t h e s e c o n d m e t h o d , 1 0 0 m l o f s a m p l e w a t e r i s p i p e t t e d i n t o a 2 5 0 m l c o n i c a l

f l a sk . 2 .0 m l o f " b a l a n c e d " b u f f e r [ 5 0 m l H C 1 ( S p . g r. = 1 . 1 8) i s a d d e d t o 4 0 0 m l

d i s t i l l e d w a t e r . 3 1 0 m l e t h a n o l a m i n e i s s l o w l y a d d e d w i t h c o n s t a n t s t i r r i n g , f o l -

l o w e d b y 5 .0 g o f m a g n e s i u m d i s o d i u m E D T A . T h e c o n t e n t i s d i l u te d t o 1 l it re ] i s

a d d e d , m i x e d a n d t h e n a d d e d o n e o r t w o d r o p s o f i n d i c a t o r s o l u t i o n [ 5 .0 g



A n a l y s i s a n d T e s t i n g i n P r e p a r a t o ry P r o c e s s e s 4 4 3

S o l o c h r o m e B l a c k W D F A (C . I. M o r d a n t B l a c k 1 1) i s d i s s o l v e d in a m i x t u r e o f 75

m l t ri e t h a n o l a m i n e a n d 25 m l a l c o h o l ] . T h e c o n t e n t is t i tr a t e d w i t h E D T A s o l u t io n( 0 . 0 2 N ) u n t i l l a s t r e d d i s h t i n g e d i s a p p e a r s . L e t t h e t it r e o b t a in e d b e T m l . S in c e 1 .0

m l o f 0 . 0 2 N E D T A s o l u t i o n - 1 .0 m g C a C O 3 ,

.'. T o t a l h a r d n e s s = 1 0 T p . p . m , a s C a C O 3.

16 .2 .4 C a l c i u m har dne s s

1 0 0 m l o f th e w a t e r s a m p l e i s p i p e t t e d i n t o a f l a s k a n d 1 m l o f 4 N - s o d i u m

h y d r o x i d e a n d o n e t a b l e t o f c a l c i u m h a r d n e s s i n d i c a t o r (B D H ) is a d d e d . T h e c o n -

t e n t is t it r a t e d w i t h 0 . 02 N - E D T A s o l u t io n u n t i l th e s o l u t i o n b e c o m e s v i o l e t (0 .1 m l

c a u s e s n o f u r t h e r c o l o u r c h a n g e ) .

.'. C a l c i u m h a r d n e s s = 1 0T p . p . m , a s C a C O 3.

1 6 .2 .5 M a g n e s i u m h a r d n e s s

T h i s i s o b t a i n e d b y d i f f e r e n c e a s f o l l o w s "

M a g n e s i u m h a r d n e ss = T o t al h a r d n e s s - C a l c iu m h a r d n e s s

( a ll v a l u e s e x p r e s s e d a s p . p . m . C a C O 3 )

M a g n e s i u m h a r d n e s s ( p . p . m . M g C O 3 ) = 0 . 8 4 x m a g n e s i u m h a r d n e s s

( p . p . m . C a C O 3 ) .1 6 .2 .6 T e m p o r a r y a n d p e r m a n e n t h a r d n e s s

1 00 m l o f w a t e r i s t i t ra t e d w i t h 0 . 0 2 N - E D T A s o l u t i o n a s d e s c r i b e d a b o v e .

A n o t h e r 1 0 0 m l o f w a t e r i s b o i l e d g e n t l y f o r 1 0 r a i n i n a 2 5 0 m l f l a s k . T h i s w i l l

d e c o m p o s e b i c a r b o n a t e s . T h e c o n t e n t i s c o o l e d , f i l t e r e d a n d t h e f i l t r a t e i s d i l u t e d

w i t h d i s t i l l e d w a t e r to m a k e u p t h e v o l u m e t o 1 00 m l a n d t h e n t i t ra t e d w i t h 0 . 0 2 N

- E D T A s o l u ti o n to o b t a in p e r m a n e n t h a rd n e s s .

T e m p o r a r y h a r d n e ss = T o ta l h a r d n e s s - P e r m a n e n t h a rd n e s s

( a ll v a l u e s e x p r e s s e d a s p . p . m . C a C O 3 ) .

1 6 .3 A n a l y s i s o f N o n - C e l l u lo s i c R e s i d u e s

S u c h a n a l y s i s i s u s e f u l a s a d i a g n o s t i c a i d i n f i n d i n g th e c a u s e o f p o o r p r e p a r a -

t i o n o r m a y b e r e q u i r e d f o r s p e c i f ic e n d u s e s , e .g . s u r g i c a l c o t t o n s .

1 6 .3 .1 A s h c o n t e n t ( m i n e r a l m a t t e r )

T h e a s h i n g o f a y a m o r fa b r ic c a n b e u s e d t o d e t e r m i n e i n o r g a n i c r e s id u e s l i k e

s i li c a t e , p h o s p h a t e , c a l c i u m , c o p p e r a n d i r o n c o n t e n t s o n t h e f a b r ic .

A p p r o x i m a t e l y 5 g o f d r i ed s a m p l e s a r e p l a c e d i n a w e i g h e d c r u c ib l e . T h e m a -t e r i a l i s s l o w l y i g n i t e d o v e r a B u n s e n f l a m e a n d t h e n t h e c r u c i b l e i s p l a c e d i n a



4 4 4 A n a l y s i s a n d T e s t i n g i n P r e p a r a t o r y P r o c e s s e s

m u f f l e f u r n a c e m a i n t a i n e d a t a t e m p e r a t u r e o f 75 0~ f o r 1 h o r u n t i l c o n s t a n t we i g h t

i s o b t a i n e d .1 0 0 x b

A s h c o n t e n t ( % ) =a

w h e r e a = d r y w e i g h t o f t h e s a m p l e ,

a n d b = we i g h t o f a sh .

T y p i c a l v a l u e s f o r g r e y c o t t o n a r e 0 .5 - 1 .0% , wh i c h d r o p s t o 0 .2 - 0 .5 % a f t e r s c o u r -

i n g a n d b l e a c h i n g .

1 6 . 3 . 2 S i l i c a t e a n d p h o s p h a t e

A p p r o x i m a t e l y 5 g s a m p l e i s a s h e d a s a b o v e a n d c o o l e d . T h e c o n t e n t i s t h e n

m i x e d w i th 5 -6 t im e s t h e a m o u n t o f s o d i u m - p o t a s s iu m c a rb o n a te ( m a d e b y m i x i n g

e q u a l w e i g h t s ) a n d t h e n h e a t e d u n t i l a c l e a r m e l t i s o b t a i n e d . O n c o o l i n g , t h e so l i d i -

f ie d m e l t i s t h e n d i s s o l v e d i n d i s t il l ed w a t e r a n d g r a n u l a r a m m o n i u m m o l y b d a t e i s

a d d e d t o i t. T h e n t h e c o n t e n t i s a c i d i f ie d w i t h n i tr i c a c i d ( 2 0% ) . I n th e p r e se n c e o f

s i l i c a te a n i n t e n se y e l l o w c o l o u r o r a y e l l o w , c r y s t a l l i n e p r e c i p i t a t e i s p r o d u c e d .

F o r t e s t i n g p h o sp h a t e c o n t e n t s i n t h e s a m p l e , t h e a sh i s d i s so l v e d i n 1 0 m l n i t r ic

a c i d ( 2 0 % ) , f i lt e re d a n d t h e re s i d u e i s m i x e d w i t h 5 - 6 t im e s t h e a m o u n t o f s o d i u m -p o t a s s i u m c a r b o n a t e a n d t h e n c o n t in u e a s a b o v e.

1 6 . 3 . 3 C a l c i u m a n d m a g n e s i u m

5 g s a m p l e i s a s h e d a n d t h e a s h i s m i x e d w i t h h y d r o c h l o r i c a c i d ( 1 0 % ) a n d

a m m o n i u m c h l o r id e . A m m o n i a ( Sp . g r. 0 .88 ) i s a d d e d u n t i l t h e so l u t io n i s a l k a l in e .

T h e a m m o n i c a l f il tr a te i s a c i d i f ie d w i t h a c e t i c a c i d a n d c a l c i u m i s p r e c i p i t a t e d w i t h

o x a l i c a c i d a s c a l c i u m o x a l a t e . T h e p r e se n c e o f c a l c i u m i s i n d i c a t e d b y a c h a r a c t e r -

i s t i c r e d f l a m e c o l o u r p l a c e d i n a b u n se n f l a m e .

F o r q u a n t i t a ti v e a n a l y s i s o f c a l c i u m , t h e f i l te r e d c a l c i u m o x a l a t e is wa sh e d w i t h

l i t t l e d i s t i l l e d wa t e r a n d t h e n t a k e n u p i n wa r m su l p h u r i c a c i d ( 2 0% ) a n d t i t r a t e d

a g a i n s t 0 . 1 N K M n O 4 s o l u ti o n .

T h e c o n c e n t r a t i o n o f c a l c i u m a n d m a g n e s i u m , e x p r e s s e d a s a p e r c e n t a g e o n

w e i g h t o f r a w c o t t o n is u s u a l l y in t h e f o l lo w i n g r a n g e s :

C a l c i u m 0 .4 3 - 0 . 1 5 %

M a g n e s i u m 0 . 04 6 - 0 .1 1 %

C a l c i u m a n d m a g n e s i u m m a y b e t a k e n u p b y t h e f i b r e d u r i n g g r o w t h o r f r o m t h e

l i q u o r d u r i n g w e t p r o c e s s in g , w h e r e t h e y a r e p r e s e n t a s h a r d n e s s f o r m e r s .



A n a l y s i s a n d T e s t i n g i n P r e p a r a t o r y P r o c e s s e s 4 4 5

1 6 . 3 . 4 I r o n a n d c o p p e r

T h e p r e s e n c e o f c o m p o u n d s o f ir o n a n d c o p p e r c an c a u s e f ib r e d a m a g e d u r i n g

b l e a c h i n g , b y s o - c a l l e d " c a ta l y t ic t e n d e r i n g " . I t i s i m p o r t a n t t o k n o w i f s u c h c o n -

t a m i n a n t s a r e p r e s e n t a n d r e m o v e t h e m p r i o r to b le a c h i n g .

0 .5 - 1 .0 g fi b r e is sp o t t e d w i t h 1 -2 d r o p s o f n i t r ic a c i d ( 5 % ) a n d a l l o w e d t o

s t a n d f o r 2 -3 m i n so t h a t a n y i r o n p r e se n t i s o x i d i s e d t o f e r r ic i o n s . T h e n 2 - 4 d r o p s

o f p o t a s s i u m t h i o c y a n a t e so l u t i o n ( 1 0% ) a r e a d d e d a n d a r e d c o l o u r i n d i c a t e s f e r r ic

i o n s . T h e i n t e n s i t y o f c o l o u r i n d i c a t e s t h e a m o u n t . T h e t e s t c a n b e c a r r i e d o u t o n

a n a s h e d s a m p l e .

I n a n o t h e r m e t h o d , t h e f i b r e i s s p o t t e d w i t h h y d r o c h l o r i c a c i d ( 1 0 % ) a n d t h e

a c i d i f ie d a r e a is s p o t t ed w i t h 1 % p o t a s s i u m f e r ro c y a n i d e . A d a r k b l u e c o l o u r i nd i -

c a t e s t h e p r e se n c e o f i ro n .

F o r t e s t i n g o f c o p p e r , t h e a sh i s sp o t t e d w i t h 5 - 1 0 d r o p s o f n i t r ic a c i d ( 1 0% ) a n d

t h e n d i l u t e a m m o n i a ( 1 :1 ) i s a d d e d u n t i l t h e a sh is a l k a l i n e . A b l u e c o l o u r sh o w s

t h e p r e s e n c e o f c o p p e r . F o r f a b r i c , th e s a m p l e i s fi rs t sp o t t e d w i t h d i l u te n i t ri c a c i d

a n d t h e n a f te r n e u t r a li s a t i o n w i t h a m m o n i a , 1 -2 d ro p s o f d i e t h y l d i t h i o c a r b a m a t e

so l u t i o n ( 0 .1 % ) a r e sp o t t e d o n to t h e s a m e a r e a . A y e l l o w c o l o u r sh o w s t h e p r e s -e n c e o f c o p p e r .

M e t a l c o n t e n t s m a y a l s o b e d e t e r m i n e d o n th e a s h b y e m i s s i o n s p e c t r o s c o p y o r

a t o m i c a b s o r p t i o n s p e c t r o s c o p y .

1 6 .4 E v a l u a t i o n o f W a x C o n t e n t o n C o t t o n

S o x h l e t e x t r a c t io n i s t h e u s u a l p r o c e d u r e f o r s e p e r a ti o n o f t h e w a x f r o m t h e

c o t to n , w i t h p e r c e n t a g e c o m p o s i t i o n b e i n g o b t a in e d b y g r a v i m e t r i c m e a n s a f te r th e

e v a p o r a t i o n o f s o l v en t . D i f f e r e n t v a l u e s a re s o m e t i m e s e n c o u n t e r e d f o r t h e s a m e

s o u r c e o f c o t t o n w h e n d i f f e r e n t s o l v e n t s a r e u s e d . S o l v e n t s c o m m o n l y u s e d a re

e t h a n o l , e t h e r , b e n z e n e , b e n z e n e - m e t h y l e n e c h l o r i d e , c h l o r o f o r m , c a r b o n t e t r a c h l o -

r i d e a n d a c e t o n e . T h e r e s u l t s o f t h e c o t to n w a x e x t r a c t e d b y th e a b o v e p r o c e s s a r e

r e p o r t e d i n T a b l e 1 6. 1. M o d e m a n a l y t ic a l t e c h n i q u e s s u c h a s g a s c h r o m a t o g r a p h y ,

m a s s s p e c t r o m e t r y a n d X - r a y d e f r a c t io n c a n b e u s e d f o r d e te c t i o n o f t h e i n d iv i d u a l

w a x c o m p o n e n t s . I t i s c o n f i r m e d t h a t a w a x y s u b s t a n c e is p r e s e n t w i t h i n t h e c r y s -

t a l l in e c e l l u l o se c h a i n . C u x a m i s u se d t o d i s so l v e t h e c o t t o n f ib r e , t h e w a x p o r t i o n

i s s e p a r a t e d t h r o u g h t h e u se o f o r g a n i c so l v e n t s , a n d g r e i g e c o t t o n i s f o u n d t o c o n -t a in a p p r o x i m a t e l y 2 % w a x . B y c o n t i n u i n g t h e e x t r a c t io n p r o c e s s , a n a d d it i o n a l




T A B L E 1 6 . 1

C o m p o s i t i o n o f C o t to n W a x [ 1

W a x P e r c e n t a g e

W a x e s te r 2 2

P h y t o s t e r o l s 1 2 - 1 4

P o l y t e r p e n e s 1 - 4

H y d r o c a r b o n s 7 - 8

F r e e - w a x a l c o h o l s 4 2 - 4 6

1 % w a x i s d e t e c t e d , e v e n t h o u g h n o r m a l e x t r a c t i o n p r o c e s s e s h a d s u g g e s t e d t h a t

t h is b a t c h o f c o t t o n c o n t a i n e d o n l y 0 . 6 - 0 . 7 % w a x .

1 6 .5 E v a l u a t i o n o f L u b r i c a n t s

S i z i n g m a t e r i a l s f o r b o t h f i l a m e n t a n d s p u n y a m u s u a l l y c o n t a in a d d i t io n a l f i l m

m o d i f i e r s to p r o d u c e a p r o d u c t w i t h i m p r o v e d s i z in g q u al it ie s . O n e s u c h c o m -

p o u n d i s l u b r i c a n t s . Lu b r i c a n t s c a n b e d i v i d e d i n to t wo b a s i c g r o u p i n g s , s a p o n i f i -

a b l e a n d u n sa p o n i f i a b l e . T h e s a p o n i f i a b l e s a r e e a s i l y r e m o v e d a n d c a n , i n f a c t a c t

a s e m u l s i f i e r s f o r t h e u n sa p o n i f i a b l e s [ 2 ] . T h e u n sa p o n i f i a b l e s , su c h a s p a r a f f i n

wa x e s , a r e c o n s i d e r e d to b e th e b e s t f r ic t i o n r e d u c e r s . T a l l o w , b l e a c h e d t a l l o w ,

h y d r o g e n a t e d t a l lo w g l y c e r id e s , a n d f a tt y e st e rs a r e u s e d a s fa ts a n d f a t t y c o m p o -

n e n t s . C r u d e - sc a l e p a r a f f i n wa x , s l a c k p a r a f f i n wa x , r e f i n e d p a r a f f i n wa x a n d so m e

p o l y e t h y l e n e s a r e u se d a s u n s a p o n i f i a b l e m a t e r i a l s . I n g e n e r a l p r a c t i c e , th e r e a r e

t h r e e g e n e r a l c a t e g o r i e s o f l u b r i c a n t s , o r k e t tl e wa x e s : wa t e r so l u b l e , wa t e r d i s -

p e r s i b l e , a n d si ze d is p e r s ib l e . W a x c o n c e n t r a t i o n s o n c o t to n y a m i n c r e a s e w e a v e

e f f i c ie n c y w h e n u s e d a t a c o n c e n t r a t i o n o f u p to 5 % . A b o v e 1 0 - 1 5 % , n o i n c re a s e

i n e ff i c i e n c y i s a c h i e v e d a n d d e s i z e p r o b l e m c a n o c c u r.

1 6 . 5 . 1 T o t a l f a t t y m a t t e r

8 - 1 0 g o f s a m p l e i s w e i g h e d i n a d r y c o n i c a l f l a s k a n d a b o u t 5 0 m l o f 2 N

su l p h u r i c a c i d i s a d d e d . T h e c o n t e n t s a r e r e f l u x e d f o r 2 h u s i n g a wa t e r c o n d e n se r .

A f t e r c o o l i n g t h e f a t ty m a t t e r i s e x t r a c t e d w i t h 5 0 m l o f e t h e r tw i c e i n a s e p e r a t i n g

f u n n e l . T h e c o m b i n e d e t h e r e x t r a c t s a re wa sh e d w i t h wa t e r t il l f r ee f r o m a c id . T h e

e t h e r e x t r a c t i s t r a n s f e r r e d t o a w e i g h i n g b e a k e r , t h e e t h e r e v a p o r a t e d u s i n g a wa t e r

b a t h a n d t h e r e s i d u e d r i e d in a n o v e n a t 11 0~ a n d we i g h e d a f t e r c o o l i n g .w e i g h t o f r e s id u e

To ta l f a t ty m a t t e r (%) = 100w e i g h t o f s a m p l e



A n a l y s i s a n d T e s t i n g i n P r e p a r a to r y P r o c e s s e s 4 4 7

1 6 .5 .2 S a p o n i f i c a t i o n v a l u e o f a n o il

0 .5 g o f th e s a m p l e i s w e i g h e d i n t o a c o n ic a l f l a s k a n d 5 0 m l o f 0 . 5 N a l c o h o l ic

p o t a s s i u m h y d r o x i d e s o l u t io n i s a d d e d t o it. T h e c o n t e n t s a r e b o i l e d u n d e r re f l u x

f o r 2 h . A f t e r c o o l i n g t h e e x c e s s a l k a l i i s b a c k - t i t r a t e d a g a i n s t 0 .5 N H C 1 u s i n g

M e t h y l O r a n g e a s an i n d ic a t o r. A b l a n k i s a l s o r u n ( w i t h o u t t a l lo w s a m p l e ) .

1 .0 m l o f 0 .5 N H C 1 s o lu t i o n = 2 8 .0 5 m g K O H

x m l o f 0 .5 N H C 1 s o l u t io n = 2 8 . 0 5 x m g K O H

W g o f s a m p l e re q u i r es 2 8 . 05 x m g K O H

28.05 x

.'. Sa p o n i f i c a t i o n v a l u e = W

w h e r e , x = ( b l a n k re a d i n g - s a m p l e r e a d in g )

1 6 . 5 . 3 U n s a p o n i f i e d m a t t e r

T h e s o l u t i o n p r e s e r v e d a f t e r t h e d e t e r m i n a t i o n o f s a p o n i f i c a t i o n v a l u e i s e x -

t r a c te d w i t h p e t r o l e u m e t h e r, e v a p o r a t e d a n d d r ie d i n a n o v e n . A f t e r c o o l i n g th e

r e s i d u e i s w e i g h e d .

w e i g h t o f r e s i d u e

U n s a p o n i f i e d m a t t e r ( % ) = x 1 00w e i g h t o f s a m p l e

1 6 .6 D e t e r m i n a t i o n o f M o i s t u r e C o n t e n t [3]

T h e a m o u n t o f m o i s t u r e i n a t e x ti l e m a t e r i a l c a n b e d e t e r m i n e d d i r e c t ly o r i n d i-

r e c tl y a n d m a y b e e x p r e ss e d e i th e r a s " m o i s tu r e c o n t e n t " o r a s " m o i s tu r e r e g a i n " .

I n th e d i r e c t m e t h o d t h e a m o u n t o f m o i s t u r e i n a d e f i n it e w e i g h t o f m a t e r i a l i s

d r i v e n o u t , u su a l l y b y h e a t i n g i n a n o v e n a t 1 05 - 11 0~ ( f o r c o t t o n ) f o r a p e r i o d o f

4 h , a t t h e e n d o f w h i c h t h e s a m p l e i s c o o l e d i n a d e s c i c c a t o r a n d t h e l o s s i n w e i g h t

i s d e t e r m i n e d . I n th e i n d i r e c t m e t h o d , a p r o p e r t y o f t h e m a t e r i a l , u su a l l y i ts e le c t r i-

c a l c o n d u c t i v i t y o r r e s i st a n c e , w h i c h i s d e p e n d e n t o n t h e m o i s t u r e c o n t e n t o f t h e

m a t e r i a l, i s m a d e u s e o f. T h e m o i s t u r e c o n t e n t , is d e f in e d a s th e m o i s t u r e p r e s e n t

i n t h e s a m p l e a n d i s e x p r e s s e d a s p e r c e n t a g e o f th e o r i g in a l w e i g h t o f t h e s a m p l e i n

t h e c o n d i t i o n i n w h i c h i t i s r e c e i v e d f o r t e st , w h e r e a s m o i s t u r e r e g a i n i s e x p r e s s e d

a s a p e r c e n t a g e o f t h e o v e n - d r y w e i g h t o f t h e s a m p l e . T h e t w o q u a n t i ti e s c a n b e

e x p r e s s e d a s f o l l o w s :

a - bM o is tu re c o nt en t (M .C .) = ~ x 100a



4 4 8 Ana lys i s a nd Te s t ing in P r e pa r a to r y P r oc e sse s

a - bM ois tu r e r e ga in ( M .R . ) = ~ x 100

bw here ' a ' an d 'b ' r epresent or ig ina l we igh t and the oven-dry we ight of the sample .

1 6 .7 T e s t s a n d A n a l y s e s o f S i z es

The w a r p s i ze , onc e a pp l i e d to the ya m a nd d r i e d , inc r e a se s the te ns i l e s t r e ng th

a n d a b r a s i o n r e s is t a n c e o f t h e y a r n . T h i s m i n i m i s e s d o w n t im e o r " b r e a k o u t s ' '.

T h e s i z in g f o r m u l a t io n s m a y c o n s i s t o f n a t u ra l a n d s y n t h e t ic p o l y m e r s , g u m s ,

s t a r che s , m e ta l - to - f ib r e lub r i c an t s , p r e se r va t ive s , a nd de f oa m e r s . The so lu t ion , a f -

t e r im pr e gn a t ion in to the wa r p ya m s a t a le ve l o f 10 - 15% ( o .w . f .) f o r c o t ton [4] a nd

c o t ton b le nd s , a nd a t a l e ve l o f 3 - 5% o n f i l a m e n t syn the t ic s , i s d r i e d in c on t inuous

f o r m o v e r d r y i n g c y l i n d e rs a n d th e n w o u n d o n t o l a rg e g o o d s c a ll e d b e a m s . T h e

c o m p o u n d s c o m m o n l y u s e d f o r f il a m e n t s i z in g a n d s p u n y a rn s i z in g a r e s h o w n i n

Ta b le 16.2 a nd 16 .3 r e spe c t ive ly . I n de s i z ing ope r a t ion the s iz e is r e m ove d a nd the

e f f e c t ive ne ss o f t he r e m ov a l o f s i z e ca n be t e s t e d de pe nd ing on the k ind o f s i ze

used .

T A B L E 1 6 . 2F i l a m e n t S iz ing M a te r i a l s

F ib r e B a s ic s i z e

N y l o n

Po lye s t e r

V i s c o s e r a y o n

Gla ss

Po lya c r y l i c a c id

Po lyv iny l a lc oho l

A c r y l ic c o p o l y m e r s

Alka l i so lub le po lyv iny l a c e ta t e

L ine a r po lye s t e r

S t y m e r ( s t y r e n e - m a l e i c an h y d r i d e co p l y m e r )

Gela t in

Po lyv iny l a lc oho l

A m y l o s e d e r iv a t iv e s

C a r b o x y m e t h y l c e l l u l o s e

B l e n d s

Po lyv iny l a l c oho l

De x t r in s

Am ylose de r iva t ive sB l e n d s



Analys i s and Tes t i ng i n P repara to ry P roces ses 449

T A B L E 1 6 . 3

S pun Yam S iz ing Mate r i a l s

Fibr e (1 O0 % or blen ds) Ba sic s ize

Co t ton

R a y o n

N y l o n

Polyes ter

Aceta te

Acryl ic

W ool

S ta rches : co rn , po t a to , t ap ioca

U n m o d i f i e d - p ea rl

Acid modi f ied , 20-60 f lu id i ty

Oxidised , severa l f lu id i t ies

D e x t r i n i z e d - B r i ti sh g u m

Derivat ized

A c e t a t e , H y d r o x y e t h y l e t h e r , A c r y l a t e ,

S t y r e n e , C r o s s - l i n k e d , C a t i o n i c , H i g h

amylose , Po lyv iny l a lcoho l , CM C, B lends

and o the r po lym ers

1 6 . 7 .1 I d e n t i f i c a t i o n o f s i z e s

S ta rches a re hydro lysed b y ac ids , a l ka li e s o r by enz ym es du r ing des i z ing p ro -

ces s. Ac id hydro lys i s o f s ta rches y i e ld mix tu res o f s acchar ides o r g lucose. Enzy-m at ic ( [3-amylase) hydrolys i s o f s tarches y ie ld mal tose and am yloglucos idase y ie lds

D-g lucose . A l l these p roduc t s g ive d i f fe ren t co lou red res idues on t r ea tmen t wi th

iod ine . Beca use o f the hydrox y l con t en t o f t he ce ll u lose , r eac t ion can occur w i th

m any d i f f e ren t com pounds . The i den t i f ica t ion o f d i f fe ren t s izes wi th t he he lp o f

d i f f e ren t r eagen t s a re summ er i sed i n Tab l e 16 . 4 . S t a rch apparen t ly con t a ins two

fract ions , a so luble amylose (10-20%) and an insoluble res idue, amylopect in (80-

90%), account for the v io le t co lour and b lue colour that are y ie lded on t rea tment

wi th i od ine . Am ylose g ives t he b lue co lou r and amy lopec t i n g ives the v io l e t t o

red-vio le t co lour . In enzym e hydrolys i s of s tarch , am ylose is complete ly hydrolysed

to am ylase [4 ] , wh ereas on ly 60% of am ylopec t i n can be hydro lysed . Tab l e 16 .5

shows the a s ses sme n t o f p re - t r ea tmen t e f fec ts on des i z ing s t a rch s ize f rom co t ton

fabr ics. Poo r rem ov al of size dur ing des iz ing m ay effect in w arp s t r ipeness , s ta ins

dur ing dye ing and p r in t i ng , uneven m erce r i za t i on and uneven abso rbancy .

N orm al ly ex t rac t ion t echn iques a re u se fu l fo r a s ses s ing t he r i n s ing e f fec t ive -

ness and s ize res idue. Sequen t ia l ex t ract ion techniqu e wi th so lvent and enz ym e [5]or water , enzy m e and so lvent [6] or so lvent , water and enzy m e [7] i s used .




T A B L E 1 6 . 4I d e n t i f i c a t i o n o f S i z e s

S i z e s R e a g e n t s P r o c e d u r e R e a c t i o n N o t e s

S t a r c h i o d i n e / p o t a s s i u mio d id e s o lu t i o n .

P o l y v i n y l i o d i n e / p o t a s s i u ma lc o h o l i o d id e s o lu t i o n ,( P V A ) b o r i c a c id s o ln .

P o l y v i n y l i o d i n e / K Ia c e t a t e s o lu t i o n .

S t a r c h + 1 2 / KI so lu t ion ,P V A b o r a x .

C M C + c o p p e r - II -A c r y l a t e s u lp h a t e s o lu t i o n .

1 . a p p ly s o lu t i o nd r o p w i s e ,2 . ru b i n g e n t ly ,3 . a s s e s s c o l o u rr e a c t i o n .

1 . a p p l y i o d i n e /p o t a s s i u m i o d i d es o lu t io n d r o p w is e2 . a p p l y b o r i ca c i d s o l u t i o nd r o p w i s e t o t h es a m e s p o t a s t h e

1 2 / KI so ln .

1 . s p o t w i t h1 2 / K I s o lu t i o n .

1 . T r e a t e d w i t hw a r m ( 7 0 ~w a te r ,2 . a q u e o u s e x t r a c ti s t e s t e d w i t h

I 2 / b o r a x .1 . c u t u p t h es a m p l e ,2 . a d d w a te r a t r a -t io 40 :1 ,3 . bo i l up fo r 10m i n ,

4 . f i l t e r o f f l iquo r

a n d c o o l ,5 . add 5 d rop s so -

l u t i o n t o t h e l i -quor ,6 . as sess r ea c t ion .

c o lo u r le s s = n o c o o l m a te -s t a r c h s i z e r ia l a n d t e s t ;p r e s e n t , b l u e n e u tr a li s ev io l e t = s t a r c h a lk a l i n ep r e s e n t, b r o w n g o o d s w i t h= m o d i f i e d a c e t i c a c i d .s t a r c h o r m i x -

t u re w i t h P V Ap r e s e n t .c o lo u r l e s s = c o lo u r i n t e n -n o P V A s it y d e p e n d sp r e s e n t , b l u e o n a m o u n t o f= P V A s iz e .p r e s e n t .

d e e p r e d d i s h c o lo u rb r o w n = p o l y - i n te n s i tyv i n y l a c e t a t e i n cr e as e s o np r e s e n t, h o t w a s h i n g .b l u e s o l u ti o n c o l o u r i n t e n -o r p r e c i p i t a t e s i ty d e p e n d s= P V A . o n P V A .

c le ar l iq u or = d i s t i n g u i s hb e t w e e nn o C M C o rC M C a n d

A c r y la t e A c r y l a t e b yp r es e n t, a d d i n g 2 - 3w h i t e t u r b id - d r o p s a c e t i ci t y /p r e c i p i t a - a c i d 8 0 % t ot i o n = C M C t h e l i q u o r ,o r Ac ry la te R e a c t i on 9

p p t . d i s -p r es e n t, s o l v e s =

C M C , p p t .u n d i s s o l v e d= A c r y l a t e .



Ana lys i s a nd Te s t ing in P r e pa r a to r y P r oc e sse s 451

T A B L E 1 6 . 5

A s s e s s m e n t o f S t a rc h S i z e o n D e s i z i n g

Ex t r a c t ion c on te n t

(wa te r ex t rac t )

T E G E W A

vio le t s c a l e

Gr e y- s t a t e f a b r ic 6 - 10 % 1

Pr e - t r e a tm e n t , goo d 0 .1 - 0 .4% 6 - 9

P r e - tr e a tm e n t , p o o r m o r e t h a n 0 . 5 % 2 -5

1 6 .7 .2 P e r c e n t a g e s iz e b y o r d i n a r y m e t h o d

Th e w e igh e d c lo th i s fi r s t w a she d in w a te r a nd the n bo i l e d in c a us t i c soda so lu -t ion ( 2%) f o r a bou t 30 to 40 r ain . The sa m ple i s wa she d a g a in in wa te r a nd bo i l e d

f o r 60 r a in in a so lu t ion o f hyd r oc h lo r i c a c id ( 1%) , a dd ing w a te r a s i t e va por a te s .

T h e s a m p l e i s w a s h e d , d r i e d s l o w l y a n d w e i g h e d . T h e d i f f e re n c e i n w e i g h t i nd i -

c a t e s the lo s s o f s i z ing m a te r i a l. I n no r m a l p r a c t ic e a l low a nc e o f 1 to 2% f o r

w e igh t lo8 8 by r e m ov ing na tu r a l im pu r i t ie s i s a l low e d du r ing the bo i l ing .

1 6 . 7. 3 E s t i m a t i o n o f t o t a l si z e b y S o x h l e t m e t h o d

5 g o f a c c u r a t e l y w e i g h e d s a m p l e i s e x t r a c t e d w i t h c h l o r o f o r m i n a S o x h l e t

e x t r a c to r f o r a bou t 1 h a t a m in im um r a t e o f 100 d rops pe r m in . The sa m ple i s t he n

dr i e d in a ir a nd wa she d in ho t w a te r s e ve r a l t im e s a nd the n r in se d by ha n d 12 t im e s .

The m a te r i a l i s t he n t r e a t e d in 0 .5% d ia s t a se so lu t ion ( 20 to 30 t im e s the w e igh t o f

c o t ton ) a t 7 0~ f o r lh a nd the n w a she d in ho t r unn ing wa te r , d r i e d a t 110 ~ a nd

we igh e d . S ide by s ide a s a m ple i s a l so t e s t e d fo r m o i s tu r e de te r m ina t ion .

1 0 0 - ( a - 1 .03 b )A p p a r e n t s iz e ( % ) = - k

a

whe r e , a = d r y w e igh t o f s a m p le ,

b = w e i g h t o f d e s iz e d s a m p l e , a n d

k = de s i z ing b la nk .

I n t h e a b s e n c e o f u n s i z e d c o n tr o l, k m a y b e t a k e n a s 3 % o f t h e d e s i z e d a n d

dr i e d sa m ple . N o c o r r e c t ion i s r e qu i r e d f o r b l e a c he d a nd dye d c lo th . Fo r to ta l s iz e

c on te n t t he a sh c on te n t ( %) o f the de s i z e d sa m ple i s t o be a dde d .

1 6 .7 . 4 T o t a l si ze b y e n z y m e m e t h o d

The m a te r i a l i s de s i z e d by us in g 5 g/1 d i a s t a se a nd 10 g /1Na C 1 a t 7 0 ~ ( pH 6 .5to 8 .5 ) f o r 1 h , li quor r a t io 40 : 1 . T he sa m ple i s w a she d tho r oug h ly in ho t a nd c o ld




wa te r a nd d r ie d . E i the r the lo s s in we igh t i s de t e r m ine d o r the c a rbohy dr a te s in the

e x t r a c t i s e s t im a te d by o x ida t ion w i th po ta s s ium d ic h r om a te unde r a c id c ond i tions .1 6 .8 D e t e r m i n a t i o n o f t h e E f f i c ie n c y o f S c o u r in g

I m m e dia t e ly f o l lowing the de s i z ing , t he ya r ns a nd f a b ri c s a re wa she d wi th de -

t e r ge n t s a nd a lka l i e s by a p r oc e ss kn ow n a s s cour ing . The e f f i c i e nc y o f s c our ing

a r e a s se s se d by the r e m ova l o f va r ious type s o f im pur i t ie s f r om the c o t ton m a te r i a l,

e .g . l o s s in we igh t , c ha ng e s in p r o te in c o n te n t ( de te r m ine d by n i t r oge n a na lys i s) ,

r e s idua l w a x c on te n t , a bso r ba nc e e t c. Apa r t f r om the se the de c r e a se in M e th y le ne

B lue a bso r p t ion i s i nd ic a t ive o f the r e m o va l o f pe c t i c subs ta nc e a nd tha t o f c oppe r

n u m b e r o f t h e r e m o v a l o f h e m i c e l l u l o s e s a n d s ug a rs .

1 6 .8 .1 M e a s u r e m e n t o f w e i g h t l o s s

5 g of dr ied sample i s t r ea ted wi th 200 ml of 1% N aO H for l h a t 80~ a f te r

wh ich the sam ple i s we l l r insed and run o ut in hot wa te r. I t i s then t rea ted in 200 ml

of 0 .5% HC1 a t 80~ for lh , a f te r w hich the sample i s once aga in r insed , boi led for

~/2 h in d is t i l led w a te r , dr ied and w eighed . W eigh t loss on scou r ing i s no rm al ly 6 -

9 %.

1 6 .8 .2 M e a s u r e m e n t o f r e s i d u a l w a x c o n t e n t [8]A known we igh t o f ove n d r i e d sa m ple i s p l a c e d in the S oxh le t e x t r a c to r a nd

r e f luxe d f o r 3 h in c h lo r o f o r m ( so lve n t ) f o r c e l lu lose a nd pe t r o l e um e the r f o r po ly -

e s t e r b l e nds . The so lve n t is d i s t i l le d - o f f a nd the f la sk c on ta in ing the sa m ple i s

r e we igh e d . The d i f f e r e nc e in we igh t w i l l g ive the fa t a nd wa x c on te n ts . Fo r we l l

b l e a c he d c o t ton , t he f a ts a nd wa x e s shou ld be be low 0 .2%. Kn i t goods shou ld

have an acceptable v a lue h igher than 2% as process in g i s des igned to a id sewabi l ity .

1 6 . 8 . 3 P r a c t i c a l t e s t o f a b s o r b a n c y

Fig . 16 - 1 shows the t e c hn ique f o r e va lua t ing we t t ing spe e d by the s t a nda r d

Dr a ve s we t t ing t e s t [9 ] . We t t ing a nd sc our ing a r e no r m a l ly a s soc ia t e d a s be ing

Figure 16-1 . Appara tus for running Draves w e t t ing te s t (Cour tesy of Union Carbide).




s y n o n y m o u s , h o w e v e r , t h is u n f o r t u n a t e l y is n o t t ru e . E x p e r i m e n t a l d a t a i n d i c a te

t h a t th e b e s t w e t t in g a g e n t s a r e u s u a l ly n o n - i o n i c s w i t h l o w e t h y l e n e o x i d e c o n t e n t ,w h e r e a s t h e b e st s c o u r in g c o m p o u n d s g e n e r a ll y h a v e a lo n g c h a i n h y d r o p h i l e a n d

h y d r o p h o b e .

H o w e v e r , t h e a b s o r b a n c y o f f ab r i c s c a n b e e s t i m a t e d b y a t e s t i n w h i c h a d ro p

o f d i s ti l le d w a t e r i s a ll o w e d t o r e m a i n i n c o n t a c t w i t h t h e s c o u r e d c l o t h f o r 3 0 s e c.

I f t h e d r o p i s a b s o r b e d i n th i s t im e , th e m a t e r i a l is j u d g e d t o b e a b s o r b a n t a n d

s u i ta b l e f o r b l e a c h i n g a n d d y e i n g . I n th e c a s e o f p r in t i n g c l o t h , t h e t i m e o f a b so r p -

t io n o f th e d r o p o f w a t e r m u s t b e l o w e r t h a n 1 s ec . T h e a s s e s s m e n t o f p r e - t r e a t-

m e n t e f f e c ts b y a b s o r b a n c y t e s t i s g i v e n i n T a b l e 1 6.6 . P o o r l y p r e - t r e a t e d g o o d s

w i l l h a v e i n c r e a s e d a m o u n t o f d y e o n t h e f i b r e s u r f a c e a s a r e s u l t o f i n a d e q u a t e

T A B L E 1 6 . 6

A s s e s s m e n t o f P r e - tr e a t m e n t b y A b s o r b a n c y T e s t

S p o t W i c k i n g t e st W i c k i n g r a te

t es t 5 m i n 1 0 m i n 1 c m 2 c m 3 c m

P r e - t r e a t m e n t

G o o d

P r e - t r e a t m e n t

P o o r

1 -5 " 3 0 - 5 0 m m 5 0 - 9 0 m m 3 - 5 " 1 0 -3 0 " 4 0 - 7 0 "

m o r e t h an < 3 0 m m

10"

< 50 m m > 10" > 30 " > 100 "

p e n e t r a t i o n , p o o r f a s m e s s p r o p e r t i e s a n d u n l e v e l d y e i n g .

1 6 .8 .4 R e m o v a l o f m o t e s ( k i t t ie s )

T h i s i s d o n e v i s u a l l y b y o b s e r v i n g t h e k i tt i es p r e s e n t o n t h e p r e p a r e d s a m p l e s ,

a n d t h e r a t i n g s o n a n a r b i t r a r y s c a le o f 1 -5 a r e g i v e n . A r a ti n g o f 5 m a y b e g i v e n t o

t h e s a m p l e w i t h n o k i t t ie s p r e s e n t o n t h e f a b ri c .

1 6 .9 T e s t i n g a n d E v a l u a t i o n o f B l e a c h i n g A g e n t s

A l t h o u g h i t is g e n e r a l l y a c c e p t e d t h a t an i m p r o v e m e n t in w h i t e n e s s is o n e o f t h e

b a s i c r e q u i r e m e n t s i n b l e a c h i n g i t is b y n o m e a n s t h e so l e o b j e c t iv e . N o w - a - d a y s

w i t h t h e i n c r e a s e d p r o d u c t i o n o f p o l y e s t e r / c o t t o n b l e n d e d f a b r ic s , p o l y v i n y l a l c o -

h o l , C M C a n d s t a r c h o r t h e i r b l e n d s a r e u s e d a s s iz i n g a g e n ts . D u r i n g e n z y m a t i c

d e s i z i n g s t a rc h s i z e s a r e b e i n g s o l u b il is e d , b u t t h e P V A a n d o t h e r p o l y m e r s w i ll b e

i n e f f ec t i v e . T h e r e f o r e , o n e o f t h e m a j o r p u r p o s e s o f b l e a c h i n g is t h e r e m o v a l o ft h e s e p o l y m e r s a p a r t f r o m t h e d e g r a d a t i o n o f t h e n a t u r a l l y o c c u r r i n g p i g m e n t s i n




the f ib re . A l so e x t r e m e ly h igh w h i t e ne ss i s no t wo r thwhi l e i f i t i s ob ta ine d a t t he

e xpe n se o f de g r a d ing the m a te r i a l be ing b le ac he d . I t i s im poss ib l e to g ive s tr i ctgu ide l ine s f o r the op t im um b le a c h ba th be c a use o f the na tu r e a nd qua l i ty o f t he

goods to be b l e a c he d , t he a m o un t o f b l e a c h ing r e qu i r e d a nd the a va i la b i l i ty o f

e qu ip m e n t in wh ic h b le a c h ing i s t o t a ke p la c e . The e va lua t ion o f e f f e c tive b l e a c h -

ing c a n be done by m e a su r ing the a bso r ba nc y , f lu id i ty , wh i t e ne ss a nd a na lys i s o f

im pu r i t i e s wh ic h shou ld be 2 - 3% or l e ss w i th a n a sh c on te n t o f 0 .20 - 0.25%. How -

e ve r e xa c t c on t r o l on the c onc e n t ra t ion o f b l e a c h ing a ge n t s i s m o s t im po r t a n t a long

wi th the t r e a tm e n t t im e , te m p e r a tu r e , pH a nd s t a b i li s a tion o f the b l e a c h ba th . The

pr oc e sse d f a b r ic shou ld be a bso rba n t , c l e a n , wh i te , un i f o r m bo t tom f o r dye ing a nd

pr in t ing .

I n the t e x ti l e i ndus t r y , i t i s qu it e c om m on to c he c k the s t r e ng ths o f so lu tions by

m ean s o f norm al i ty , m ola r i ty , spec i f ic gravi ty , dens i ty , pe rcentage and g /1 of ava i l-

a b le c h lo r ine . B le a c h l iquor s , m e r c e r i z ing l iqu ids a nd r e s in so lu tions a r e c he c ke d

wi th hy dr om e te r f o r de t e r m in ing spe c if ic g r a v i ty a nd s t re ng th i s e xp r e s se d in te r m s

of de g r e e s Tw a dde l l ( ~ S om e t im e B a um e ( ~ i s a l so use d to e xpr e s s the

s t r e ng th in so lu t ion . The r e la t ions a m ong the th r ee c om m o n m e thods f o r e xp r e s s -ing the de ns i ty o f so lu t ions c a n be s im p l i f ie d by a r i thm e t i c a l e xp r e s s ion f o r qu ic k

rout ine checking .

145spe c i fi c g r a v i ty = 14 5- ~

145~ = 145 -

spec i f ic gravi ty

spec i f ic gravi ty = 0 .005 (~ + 1

~ = 20 0 ( spe c if i c g r a v i t y - 1 )

g / 1p r e c e n t b y w e i g h t =

10 (specif ic grav ity)

pounds pe r ga l lon = g /1 x 0 .008345

The re la tionship be twe en ~ and s t rength of b leaching pow der so lu t ion i s shown

in Tab le 16 .7 . Th ese meth ods o f exp ress ing s t rengths of so lu t ions , ho w eve r a re fa rf rom acc ura te and hence q uant i ta t ive es t im at ion by t it r a t ion for prac t ica l cont ro l of

b le a c h in g ope r a t ion i s p r e f e ra b le .




T A B L E 1 6 . 7

F r e s h B l e a c h i n g P o w d e r S o l u t i o n s [ 1 0]

~ Av a i l ab le ch lo r ine , g /1

0.5 1 .40

1 2 .71

2 5 .58

3 8.41

4 11.41

5 14 .476 17 .36

7 2 0 . 4 4

8 2 3 .75

9 2 6 .62

1 0 2 9 .5 0

1 5 4 5 .70

2 0 61 .5 0

1 6 .9 .1 A n a l y s i s o f b l e a c h i n g p o w d e r

5 g s a m p l e i s m a d e u p t o 5 00 m l i n a v o l u m e t r i c f l a sk . 5 0 m l o f th i s so l u t i o n i s

p i p e t t e d o u t t o a 2 5 0 m l c o n i c a l f l a sk a n d 2 5 m l o f d i s t i l l e d wa t e r i s a d d e d f o l -

l o w e d b y 2 0 m l o f K I so l u t i o n ( 1 0% ) a n d 1 0 m l o f g la c i a l a c e t i c a c id . T h e l i b e r -

a t e d i o d i n e i s t i t r a t e d a g a i n s t N /1 0 so d i u m t h i o su l p h a t e so l u t i o n u s i n g s t a r c h so l u -

t io n a s i n d i c a t o r t o w a r d s t h e e n d p o i n t w h e n t h e b l u e c o l o u r w i ll b e d i s c h a r g e d .

C a ( O C 1 )2 + 4 K I + 4 C H 3 C O O H --+ C a C 1 2 + 4 C H 3 C O O K + 2 I 2 + 2 H 2 0212 + 4N a2S2 03 --~ 2Na2S4 O6 + 4N aI

1 m l o f 0 .1 N N a 2S2 03 = 0 .003 5 5 g a v a i l a b l e c h l o r i n e

% a v a i l a b l e c h l o r i n e = B . R . x N o r m a l i t y o f Na2S203 xE q . w t . o f C12 5 0 0

X

1 000 5 0

100

w t . o f s a m p l e (W )

= B . R . x3 . 5 5

W




1 6 .9 . 2 A n a l y s i s o f s o d i u m h y p o c h l o r i t e

T h e e s t i m a t i o n b y a b o v e m e t h o d e x p r e s s e s c h l o r a t e s a s w e l l a s h y p o c h l o r i t e s a sa v a i l a b l e c h l o r i n e . T h e e r r o r s d u e to c h l o r a t e s c a n b e a v o i d e d b y t i t r a ti o n w i t h a n

N / 1 0 s o l u t i o n o f s o d i u m a r s e n i te ( N a 2 H A s O 3 )

1 m l o f 0 . 1 N N a 2 H A s O 3 = 0 . 0 0 3 5 4 6 g c h l o r in e .

1 6 . 9 .3 A n a l y s i s o f s o d i u m c h l o r i t e

2 g s a mp l e i s m a d e u p t o 5 0 0 m l i n a v o l u m e t r i c f l a sk . 2 5 ml o f s o l u t i o n i s

p i p e t t e d o u t a n d t h e n 2 5 m l o f 1 0 % K I s o l u t i o n a n d o f 1 0 % H 2 S O 4 a r e a d d e d . T h e

c o n t e n t i s t i t r a t e d a g a i n s t 0 . 1 N N a 2 S 2 0 3 s o l u t i o n u s i n g s t a r c h a s a n i n d i c a t o r t i l l

b l u e c o l o u r d i s a p p e a r s c o m p l e t e l y .

2 N a C 1 0 2 + 8 K I + H2SO 4 ---->2 N a C 1 + K 2 S O 4 + 8 I + H 2 0

1 m l o f 0 . 1 N N a 2 S2 03 - 0 . 0 0 2 2 6 g N a C 1 0 2

5 0 0 1 0 0E q ' w t ' ~ x ~ x% N a C 1 0 2 B . R . x n o r m a l i t y of Na2S203 x2 5 W0 0 0

1 m l o f 0 . 1 N K M n O 4 = 0 . 0 01 7 g H202

o~ H202 = B . R . x N o r m a l i t y o f K M n O 4 x

= B.R. x 1 .7

E q . w t . o f H 2 0 2 1 0 00 1 0 0X ~ X ~1000 10 10

G e n e r a l l y , H202 c o n c e n t r a t i o n i s e x p r e s s e d i n v o l u m e . 1 0 v o l u m e H202 = 10

t i m e s i ts v o l u m e o f 0 2 w h i c h c o r r e s p o n d s to 3 % s o lu t io n b y w e i g h t o f H202. T o

c o n v e r t % H202 i nt o v o l u m e of H202 f o l l o w i n g c a l c u l a t i o n s c a n b e u s e d 9

112V o l u m e o f H ~O 2 = % o f H 2 02 x .

- 3 4

4 . 5 2= B . R . x ~

W

1 6 .9 . 4 A n a l y s i s o f h y d r o g e n p e r o x i d e

1 0 m l o f s a m p l e s o l u t i o n i s d i lu t e d t o 1 0 0 0 m l w i t h d i s t i l le d w a t e r . 1 0 m l o f t h i s

s o l u t i o n i s p i p e t t e d o u t i n t o a c o n i c a l f l a s k a n d 1 0 m l o f 1 0 % H 2 S Q i s a d d e d t o i t.

T h i s s o l u t io n i s t h e n t i t ra t e d a g a i n s t 0 .1 N K M n O 4 t il l p i n k c o l o u r o f p e r m a n g a n a t e

s o l u t i o n p e r s i s t .

5H202 4- 2KM nO 4 + 3H2SO 4 ~ K2SO 4 + 2M nS O 4 + 8H20 +50 2



A n a l y s i s a n d T e s t i n g i n P r e p a r a to r y P r o c e s s e s 4 5 7

1 6 .9 . 5 A n a l y s i s o f s ta b i l is e r s f o r p e r o x i d e b l e a c h

T h e e f f i c i e n c y o f a s ta b i l is e r f o r p e r o x i d e b l e a c h i s te s t e d b y t i t r i m e t r i c d e t e r m i -

n a t i o n o f t h e s p e e d o f d e c o m p o s i t i o n o f H 2 02 , i n t h e p r e s e n c e a n d a b s e n c e o f

s t a b i li s e r , d u r i n g t h e b l e a c h i n g o f c o t to n . B l e a c h i n g b a t h s c o n t a i n i n g 1 0 m l /1 H 2 02,

5 m l /1 N a O H ( 67~ a n d 0 , 0 .2 5 , 0 .5 a n d 1 g /1 s t a b i l is e r s a r e p r e p a r e d b y a d d i n g

s t a b i l is e r , c a u s t i c so d a a n d H 2 02 , i n t h a t o r d e r , to wa t e r . C o t t o n c l o t h p i e c e s ( 5 g )

a r e b l e a c h e d i n t h i s so l u t i o n s a t 90~ f o r 90 m i n , m a t e r i a l to l iq u o r ra t i o b e i n g

1 :5 0 . A f t e r r e p l e n i s h i n g w a t e r lo s t d u e t o e v a p o r a t i o n , a b o u t 2 5 m l s a m p l e s a r e

wi t h d r a wn a f t e r 0 , 3 0 , 60 a n d 90 m i n , c o o l e d i n i c e wa t e r a n d a 5 m l a l i q u o t i s

p i p e t t e d f r o m t h e se f o r a n a l y s i s . I t i s d i l u t e d w i t h 5 0 m l o f d i s t il l e d wa t e r , a c i d i f i e dw i t h 1 0 m l o f 2N H2SO 4 a n d t i t r a t e d w i t h 0 . 1 N p o t a s s i u m p e r m a n g a n a t e t o a

p e r m a n e n t p i n k c o l o u r.

I n t h e c a se o f s t ab i l is e r s w h i c h c o n s u m e p e r m a n g a n a t e u n d e r t h e s e c o n d i t i o n s ,

t h e d e t e r m i n a t i o n i s d o n e i o d o m e t r i c a ll y b y a d d i n g 1g K I to t h e a c i d i f i e d so l u t i o n

a n d t i t r a t e d t h e i o d i n e l i b e r a t e d , a f t e r k e e p i n g i n d a r k f o r 1 0 m i n , w i t h 0 .1 N so -

d i u m t h i o s u l p h a t e u s i n g s t a rc h a s a n i n d ic a t o r.

1 m l 0 .1 N K M n O 4 = 0 .001 7 g H2 02

1 m l 0 .1 N N a 2 8 2 0 3 = 0 .001 7 g H2021 6 . 9. 6 A n a l y s i s o f s o d i u m h y d r o s u l p h i t e

2 g s a m p l e i s d i s s o l v e d i n a m i x t u r e o f 1 0 m l H C H O a n d 2 5 m l w a t e r i n a

2 5 0 m l v o l u m e t r i c f l a sk . T h e s t o p p e r e d f l a s k is a l lo w e d t o s ta n d f o r 5 m i n a n d t h e

v o l u m e i s m a d e u p to th e m a r k . 2 5 m l o f t h i s so l u t i o n i s p i p e t t e d o u t a n d ti t r a te d

a g a i n s t 0 . 1 N 12 so l u t i o n u s i n g s t a r c h so l u t i o n a s a n i n d i c a t o r t i l l b l u e c o l o u r p e r -

sists.

1 m l o f 0.1 N 12 = 0 .004 3 5 g Na2S204

4 .3 5% N a 2 8 2 0 4 = B . R . x ~ .

W

1 6 . 9 . 7 A n a l y s i s o f s o d i u m b i s u l p h i t e

1 0 g s a m p l e i s a c c u r a t e l y we i g h e d a n d d i s so l v e d i n 1 l it r e d i s t i ll e d wa t e r . T o 1 0

m l o f t h is so l u t i o n 5 m l a c e t i c a c i d i s a d d e d a n d t h e n t i t r a te d a g a i n s t 0.1 N I ,

so l u t io n u s i n g s t a rc h so l u t i o n a s an i n d i ca t o r. E n d p o i n t is j u d g e d w h e n t h e c o l o u r le s s

so l u t i o n t u r n s b l u e .

N a H S O 3 + I 2 + H 2 0 - - ~ N a H S O 4 + 2 H I

1 m l o f 0 .1 N 12 = 0 . 00 5 2 g N a H S O 3

% N a H S O 3 = B . R . x 5 2 .



4 5 8 An a ly s i s an d T es t i n g i n P rep a r a to r y P r o ces s es

1 6 .9 . 8 E s t i m a t i o n o f s o d i u m s i li c a t e

In a c o m m er c i a l s am p le o f s i l ic a t e , N a 2 0 ( to t a l a lk a l i) an d S iO 2 ( s i li ca ) a r ed e t e r m in ed . 5 g o f s o d iu m s i li ca t e i s d i s s o lv ed i n 1 00 m l w a te r . 1 0 m l o f t h is

so lu t ion i s t i t r a ted aga ins t 0 .5 N H2SO 4u s in g M eth y l e O r an g e a s an i n d ica to r .

1 ml 1N H2SO 4 = 0 .031 g N a20

F o r d e t e r m in a t i o n o f s il ica , 2 0 m l o f s i li c a te s o lu t io n i s k ep t i n an ev a p o r a t i n g

d i s h an d t h en 2 0 m l o f N HC1 i s ad d ed t o i t. T h e co n t en t is ev ap o r a t ed t o d r y n es s

w i th co n s t an t s t i rr i n g . Af t e r co o l in g 1 0 m l o f N HC1 is ad d ed an d ag a in ev ap o -

r a t ed t o d r y n es s . T h e co n t en t i s b ak ed (o v e r a s an d b a th ) at ab o u t 1 3 0~ to co n v e r t

the s i li c i r ac id in to s i li ca . Af te r coo l ing wa ter is adde d to d i sso lve the so lub le

m a t t e r an d t h en f i lt e red t h r o u g h a w e ig h ed - as h f il t er p ap e r , w as h e d f ree f r o m ch lo -

r ide ( tes t the f i l tr a te wi th d i lu te Ag N O 3 so lu t ion) . The c on ten t i s inc ine ra ted and

w e ig h e d a s s i li ca .

1 6 .1 0 A s s e s s m e n t o f D a m a g e o f C e l lu l o se D u r i n g P r e - t r e a t m e n t P r o c e s s e s

T h e d a m a g e s t h a t o c c u r d u ri n g v a r i o u s p r e - tr e a t m e n t p r o c e s s e s o f c e ll u lo s i c

f i b re s can b e d e t ec t ed b y v a r io u s ch em ica l t e s t s li k e f lu id it y , co p p e r n u m b er , M e th -

y l en e B lu e ab s o r p t i o n an d s i l v e r n i t r a te s t a in in g e t c .1 6 .1 0 .1 D e t e r m i n a t i o n o f fl u id i t y o f c e ll u lo s e

T h e e x t en t o f ch em ica l d a m ag e t o ce l l u lo s i c f i b r e s is u s u a l l y ex p r es s ed f r o m

f lu id i t y m eas u r em en t s , a l t h o u g h w i th o x id a ti v e d am a g e s o m e p r o b l em s a r is e . F lu -

id i t y i s t h e i n v e r s e o f v i s co s i t y o f ce l l u lo s e s o lu t i o n an d i s m eas u r ed a s r h es .

Ox y ce l lu lo s e o r h y d r o ce l l u lo s e h as eq u a l e f f ec t u p o n v i s co s i t y an d g iv e o v e r a l l

d eg r ad a t i o n o f ce l lu lo s e . Deg r ad a t i o n i s a lw ay s acc o m p an ied b y a d ec r eas e i n DP ,

th e r e f o r e h ig h e r t h e v i s co s i t y th e l e s s is th e d am ag e w h ich h as b een i n f l i c t ed u p o n

th e f i br e . V i s co s i t y ch an g es d o n o t g iv e a s t r a ig h t l in e p lo t in re l a t i o n t o l o ss o f

t en s i l e s t r en g th . W h en f l u id i t ie s a r e u sed , h o w e v e r , t h e cu rv e i s n ea r en o u g h to a

s t r a igh t l ine fo r a ll p rac t ica l purpo ses .

A m o n g t h e v a r i o u s s o l v e n t s s u g g e s t e d f o r d i s s o l u t i o n o f c e l l u l o s e ,

cu p r am m o n iu m s o lu t i o n i s r eco m m en d ed a s a g en e r a l s o lv en t h av in g 1 5 _+ 0 .1 g/1

Cu, 200 + 5 g /1N H 3 and less than 0 .5 g /1 n i t rous ox ide . The f lu id i ty in th i s so lve n t

o f th e s o lu t i o n o f co tt o n i s g iv en b y

CF = -

t



A n a l y s i s a n d T e s t i n g i n P r e p a ra t o r y P r o c e s s e s 4 5 9

wh e r e , c is the v i sc o m e te r c ons ta n t . I f i t i s ne c e s sa r y to a pp ly k ine t i c e ne r gy c o r -

rec t ion , k ,

CF ~ ~

kt ~

t

The k ine t i c e ne r gy c o r r e c t ion i s unn e c e ssa r y f o r t im e s o f f low g r e a te r t ha n 20 0 se c .

I n a c tua l p r a c t i c e 0 .5 g o f fine ly c u t d r y c o t ton sa m ple i s d i s so lve d in 10 0 m l o f

s t a n d a r d i s e d c u p r a m m o n i u m h y d r o x i d e s o lu t io n . T h e v i s c o m e t e r ( Fi g . 1 6 -2 ) i s

B!

!

1

)Figur e 16 -2 . S h i r l e y X - type v i sc o m e te r a nd j a c ke t .

u se d f o r d i s so lv ing a s we l l as f low t im e o f c e llu lose so lu tion . The v i sc om e te r tube

i s c a l ib r a t e d . The th r e e m a r ks on the tube a r e t im ing m a r ks . The r a t io o f t he t im e

o f f lo w f r o m B C t o C D s h o u l d b e n e a r u n i ty . T h e v i s c o m e t e r is t h e n w r a p p e d w i t h

b la c k c lo th a nd wo un d on a c yc le whe e l w h ic h r o t a t e s a t 4 r. p .m , ove r n igh t . S t e e l

c y l inde r o r Hg p la c e d in s ide the c y l inde r f a l l s f r om one e nd to the o the r du r ing

r o ta t ion . Th e e s t a b l i she d p r oc e d ur e [11 ,12 ] invo lve s long a g i t a t ion o f c e l lu lose

w i t h t h e s o l v en t . A m o d i f ie d m e t h o d i s a ls o d e s c r ib e d w h i c h g i v e s o n l y s l ig h t l y

l e s s a c c u r a t e r e su l t s i n a m u c h sho r t e r t im e [ 13 ].




C h e m i c a l l y u n d a m a g e d c o t t o n h a s a fl u i d it y o f 3 t o 5. A v a l u e o f 1 0 o r m o r e

c a n b e t a k e n a s a n i n d i c a ti o n o f e x c e s s i v e d e g r a d a t i o n d u r i n g c h e m i c a l p r e - tr e a t -m e n t p r o c e s s e s . I t is u s u a l t o w o r k w i t h 2 % s o l u t i o n in t h e c a s e o f r e g e n e r a t e d

c e l l u l o se . U n p r o c e s s e d v i s c o se h a s a f l u i d i t y o f 1 0 t o 1 2. T h e f l u i d i t y v a l u e s c a n

b e e x p r e s s e d i n t e r m s o f D P o f c e ll u l o s e b y t h e f o l l o w i n g e q u a t i o n [ 1 4] :

DP = 216 0 [ ( logr l~ + 1) - 0 .267]

w h e r e r l, i s t h e r e la t i v e v i s c o s i t y o f 0 . 5 % s o l u t io n o f c el lu l o s e i n C u o x a m c o m -

p a r e d t o t h e v i s c o s i t y o f t h e s o lv e n t . W h e n t h e f lu i d i ty m e a s u r e m e n t s i n d i f f e re n t

s o l v e n t s a r e c o m p a r e d , i t i s o b s e r v e d t h a t t h e a p p a r e n t D P o f t h e d e g r a d e d ( o x i d a-

t i v e ) c o t t o n i s d e p e n d e n t o n t h e a l k a l i n i t y o f t h e so l v e n t [ 1 5 ] :

DPEwNN < DPcuEN < D P < D PUOXAM NO3AI

F l u i d i t y r e s u l ts d e t e r m i n e d i n C u x a m a n d C u e n f o r c h e m i c a l ly d a m a g e d c o t to n

a r e c o r r e l a te d w i t h v i s c o s i t y v a lu e s o b t a i n e d i n C a d o x e n a n d F e T N a s o l v e n t s [ 1 6] .

T h e c o m p a r i s o n a n d c o n v e r s i o n o f t h e v i s c o s i ty v a lu e s to a p p a r e n t c u p r a m m o n i u m

f l u i d i ty i s a q u i c k m e t h o d o f d e t e r m i n i n g d e g r a d a t i o n o f c o t to n o c c u r e d i n p r e -

t r e a t m e n t p r o c e s se s [ 1 6] .

1 6 .1 0 .2 D e t e r m i n a t i o n o f c o p p e r n u m b e rC o p p e r n u m b e r i s an e x p r e s s i o n o f t h e r e d u c i n g p o w e r o f d e g r a d e d c e l lu l o s e s .

O x i d a t i o n o f c e ll u l o se c a n p r o d u c e r i n g f i s s i o n o f t h e g lu c o se r e s i d u e s , r e su l t i n g i n

t h e f o r m a t i o n o f a l d e h y d e g r o u p s a t c a r b o n a t o m s 2 a n d 3. T h e a l d e h y d e g r o u p s

c a n r e d u c e F e h l i n g ' s so l u t i o n t o c u p r o u s o x i d e . T h e l a t te r m a y b e d e t e r m i n e d q u a n -

t i t a t iv e l y b y a l l o w i n g t h e o x i d e t o r e d u c e f e r ri c a l u m t o th e f e r r o u s s t a te a n d d e t e r -

m i n i n g t h e l a tt e r b y t i tr a ti o n w i t h a m m o n i u m c e rr ic s u lp h a te . T h e c o p p e r n u m b e r i s

t h u s t h e w e i g h t o f c o p p e r f r o m C u 2§ to C u § s t a t e by 100 g d ry ce l lu lose and i s a

m e a s u r e o f i ts in t e r a n d i n t ra c h a i n b r e a k d o w n . P u r e c e l lu l o s e h a s a c o p p e r n u m -

b e r o f 0. 2 - 0 .3 a n d w h e n f u l l y d e g r a d e d m a y b e a s h i g h a s 1 4. T h e i m p o r t a n c e o f

c o p p e r n u m b e r h a s s u f f e re d a d e c l in e b e c a u s e i t h a s b e e n d e m o n s t r a t e d t h a t t h e re is

a poo r cor re l a t ion be tw een inc rease in coppe r nu m be r and dec rease in t ens i le s t r eng th .

F o u r s o l u t io n s a r e p r e p a r e d a s f o l l o w s :

So l u t i o n A : 1 00 g p u r e C u S O 4 d i s so l v e d i n 1 l it r e H 2 0 .

So l u t i o n B 9 0 g Na H C O 3 a n d 3 5 0 g Na 2 C O 3 d i s so l v e d i n 1 l it r e H 2 0 .

So l u t i o n C : 100 g f e rr i c a l u m a n d 1 4 0 m l p u r e c o n c e n t r a t e d H 2 SO 4 d i s so l v e d

in 1 l i t re H20.

So l u t i o n D : N /1 00 c e r r ic su l p h a t e .



A n a l y s i s a n d T e s t i n g i n P r e p a r a to r y P r o c e s s e s 461

S o l u t i o n A a n d B a r e m i x e d i n p r o p o r t i o n 5 t o 9 5 a n d t h e m i x t u r e i s b o i l e d .

0 .1 2 5 g f i n e l y c u t d r i e d s a m p l e i s k e p t in a p y r e x t e s t tu b e a n d 1 00 m l o f t h e

m i x t u r e ( A a n d B ) i s a d d e d t o it. T h e t e s t t u b e i s i m m e r se d i n a c o n s t a n t l e v e l wa t e r

b a t h w h i c h i s k e p t b o i li n g . T h e t e s t t u b e is c o v e r e d w i t h l o o s e g l a s s b u l b d u r i n g

b o i l i n g . A f t e r 3 h t e s t t u b e s a r e t a k e n o u t , c o o l e d a n d t r a n s f e r r e d o n t o G o o c h c r u -

c i b l e a n d f i l te r e d w i t h su c t i o n . T h e s a m p l e i s w a sh e d , f i rs t w i t h d i lu t e so d i u m c a r -

b o n a t e so l u t i o n (5 g /l ) a n d su b se q u e n t l y w i t h h o t w a t e r . T h e r e s i d u e i s t h e n wa sh e d

w i t h so l u t i o n C t w i c e w i t h a b o u t 5 m l e a c h t i m e . T h e r e s i d u e i s t h e n f i n a l l y w a sh e d

w i t h a b o u t 1 0 m l o f 2 N H 2 SO 4. D i s t i l l e d wa t e r is a d d e d . T h e f i lt r a te a n d wa sh i n g s

a r e c o l l e c t e d a n d t h e n t i t r a t e d w i t h N /1 00 c e r r ic su l p h a t e so l u t i o n u s i n g f e r r o i n ( 2 -

3 d r o p s ) a s i n d i c a t o r u n t i l th e c o l o u r c h a n g e s f r o m r e d t o p a l e b l u e .

1 000 m l o f N /1 00 c e r r ic su l p h a t e = 0 .00063 5 g C u ( r e d u c e d )

100C o p p e r N u m b e r = B . R . x 0 1 00 06 3 5 x

0 .125

= B.R. x 0 .508

T h e c u p r o u s o x i d e r e d u c e s f e r r ic a l u m a s f o l lo w s "

C u + + F e 3+ __~ C u 2+ + F e 2+and f ina l t i t r a t ion w i th ce r r i c su lp ha te inv o lve s the ox ida t ion Fe 2+ --~ Fe z+ [ 18].

1 6 . 1 0 . 3 M e t h y l e n e B l u e a b s o r p t i o n t e s t

M e t h y l e n e B l u e t e st c an a l s o b e u s e d to d i f f e re n t i a te b e t w e e n o x y c e l l u l o s e a n d

h y d r o c e l l u l o se . M e t h y l e n e B l u e i s a c a t io n i c d y e . S t a n d a r d c e l l u l o se g e n e r a l l y h a s

n o a f f i n i t y fo r M e t h y l e n e B l u e , b u t o x y c e l l u l o s e w i t h t h e f o r m a t i o n o f c a r b o x y l

g r o u p s c o n f e r a n a f f i n i ty a n d c a n b e s o r b e d o n t o c o t to n . F o r t h is p u r p o s e , M e t h y l -

e n e B l u e a b so r p t i o n t e s t s a r e c a r r ie d o u t b o t h a t p H o f 7 .0 a n d a t a p H o f 2 .7

( a ci d ic ) . T w o p i e c e s o f fa b r i c s to b e t e s t e d a r e t a k e n a n d t r e a t e d o n e w i t h M e t h y l -

e n e B l u e a t a p H o f 2 .7 a n d t h e o t h e r a t p H 7 .0 . I f o x y c e l l u l o s e i s p r e se n t , t h e

m a t e r i a l w i l l a b so r b l e s s d y e i n t h e a c i d th a n i n t h e n e u t r a l so l u t i o n , w h i l s t re v e r s e

i s t h e c a se i f h y d r o c e l l u l o se i s p r e se n t . T h e d e g r e e o f s t a i n i n g w i l l i n d i c a t e t h e

e x t e n t o f d e g r a d a t io n .

I n a n o t h e r m e t h o d , 1g c a ti o n f r e e s a m p l e i s t r e a te d w i t h 1 00 m l o f M e t h y l e n e

B l u e s o l u t i o n (1 0 m . m o l e s / l ) b u f f e r e d i n p r e s e n c e o f p o t a s s i u m d i h y d r o g e n p h o s -

p h a t e ( 0 . 6 2 5 m . m o l e s / l ) a n d N a O H ( 0. 4 m . m o l e s /l ) . T h e c o n t e n t s o f t h e f la s k a rea g i t a t e d f o r a b o u t 1 8 h a t r o o m t e m p e r a t u r e . T h e s o l u t io n i s p o u r e d o f f f r o m t h e



4 6 2 Ana lys i s a nd T e s t ing in P r e pa r a to r y P r oc e sse s

c e l lu los i c s a m p le a nd p r e f e r a b ly c e n t r i fuge d . The sup e m a te n t so lu t ion i s su i t a b ly

d i lu t e d to de te r m ine the a bso r ba n c e a t 6 20 nm . The lo s s in c onc e n t r a t ion o f thedye in the t r e a ting so lu t ion i s f ound ou t by r e f e r r ing to the c a l ib r a tion g r a p h a nd the

c a r bo xy l c on te n t o f t he c e llu lose sa m p le is c a l c u la t e d a nd e xpr e s se d a s m .e q /10 0 g

dr y c e l lu lose .

I f a dye d m a te r i a l i s unde r t e s t, t he s t r ipp ing o f dye wi ll be ne c e s sa r y be f o r e the

t e s t c a n be c a r r i e d ou t. A l t e r na t ive ly , de g r a d a t ion c a n be de te r m ine d by t i t r a tion

us ing a n a n ion ic dye wh ic h p r e c ip i ta t e s M e thy le ne B lue f rom so lu t ion .

S c ou r e d a nd b le a c he d Am e r ic a n c o t ton ha ve c a r boxy l c on te n t s o f 0 .8 - 0.9; Eg yp-

t i a n c o t ton 1 .16- 1 .7 4 . Unbuf f e r e d M e thy le n e B lue so lu tions g ive lowe r va lue s v i z .,

0 .45 a n d 0.65 r e spe c t ive ly . M e thy le n e B lue a bso r p t ion o f c o t ton de pe nds on the

a sh a lka l in i ty o f t he c o t ton a nd the va lue de c r e a se s a s the a sh a lka l in i ty de c r e a se s .

1 6 . 1 0 . 4 S i l v e r n i t r a t e t e s t

Th is qu a l i ta t ive te s t i s a l so re fe r red to as Ha r r iso n ' s te s t s ince he was the f i rs t to

de sc r ibe i t i n 19 12 . The t e s t spe c im e n i s e i the r bo i l e d o r pa d de d w i th a r e a ge n t

c on ta in ing a m ix tu r e o f s ilve r n i t r a t e (1%) , sod ium th iosu lpha te ( 4% ) a nd sod ium

h y d r o x i d e ( 4 % ) a n d t h e n s t ea m e d . T h o s e p a r t s w h e r e d e g r a d a t io n t a k e s p l a c e d u eto oxyc e l lu lose o r hydr oc e l lu lose in a f a b r ic w i l l be s t a ine d b la c k o r da r k g r e y due

to the f o r m a t ion o f s ilve r by r e duc t ion .

1 6 .1 0 .5 D e t e r m i n a t i o n o f a c i d ic g r o u p s b y io d o m e t r i c m e t h o d

1 g o f bone d r y c a t ion f r e e d sa m ple i s t r e a te d w i th 50 m l so lu t ion [Na C 1 ( A .R . )

50 g, KI (CP) 83 g, KIO 3 (CP) 21 .4 g , sod ium th iosu lpha te c r ys t a l s 4 .9 6 g d i s -

so lv ed in 2 li t r e s of wa te r ] in a s top pered f la sk . To th is 25 ml o f CO2-f ree d is t i l led

w a te r i s a dde d . A c u r r e n t o f C O2- fr e e a i r i s a l so bub b le d th r ou gh the so lu t ion a nd

w ate r wa shin g the bubb l ing g lass tube w i th 25 ml CO2-free d is t i lled wa te r , the f la sk

i s s toppe r e d a nd ke p t f o r 24 h . The c o n te n t s in the f l a sk a re t i tr a t e d wi th 0 .0 2 N

iod ine so lu t ion us ing s t a r c h ind ic a to r. The e nd po in t i s i nd ic a t e d by the a ppe a r a nc e

of a f a in t b lue c o lou r .

l x ( a - b ) x N x l 0 0 x l 0 0 0C a r b o x y l c o n t en t (m . e q. C O O H / 1 0 0 g ) =

1 0 0 0 x W

whe r e , a a nd b a r e the t i tr a t ion r e a d ings f o r b l a nk a nd sa m ple ,

N = no r m a l i ty o f iod ine so lu t ion ,

a n d W = b o n e d r y w e i g h t o f t h e s a m p l e .



An aly s i s an d T es t i n g i n P r ep a r a to r y P r o ces s es 4 63

1 6.1 1 A s s e s s m e n t o f D a m a g e o f W o o l

W o o l f i b r e d u r in g it s v a r io u s p r e - t r ea tm en t s t ag es a l s o u n d e r g o e s s o m e k in d o fd a m a g e , t h e e x t e n t o f w h i c h m a y b e a s s e s s e d b y b o t h p h y s ic a l a n d c h e m i c a l m e t h -

o d s . T h e v e r y m u l t i p l i c i t y o f t e s t s av a i lab l e i s i n it s e l f ev id en c e o f t h e l ack o f a

u n i v e r s a l m e t h o d f o r a s s e s s m e n t o f d a m a g e [ 1 9] .

1 6 .1 1 .1 M i c r o s c o p i c t e s t

M o d i f i ca t i o n o f t h e ex t e r n a l s ca le s t r u c tu re o f w o o l b y ch em ica l t r ea tm en t can

b e e x a m i n e d v i s u a l ly w i t h th e a i d o f m i c r o s c o p e .

W o o l i s im m er s ed i n a d i l u te s o lu t io n o f M e th y l en e B lu e (0 .4 g / l) f o r 1 r a in an d

w a s h ed i n w a te r f o r 5 m in an d f i n a l ly d r i ed . T h e s t a in ed f i b r e s a re t h en cu t i n to

s h o r t le n g t h s o f a b o u t 1 m m a n d t h e n m o u n t e d i n a l iq u i d p a r a f fi n a n d e x a m i n e d

u n d e r m i c r o s c o p e o f a b o u t 2 0 0 . T h e d e g r e e o f d a m a g e is t h e n e x p r e s s e d i n c o m -

p a r a t i v e n u m er i ca l t e r m s d ep en d in g o n th e ex t en t o f s t a in in g .

Al t e r n a t i v e ly , d am ag e t o t h e o u t e r l ay e r s (ep i cu t ic l e ) m ay b e r ev ea l ed b y m e an s

Al lw ' 6 rd en r eac t i o n [2 0 ]. W h en w o o l f ib r e s a r e im m er s ed i n ch lo rin e o r b r o m in e

w a te r , b u b b le s o r b l i s t e r s k n o w n as Al lw ' 6 r d en s acs a r e f o r m ed o n t h e s u r f ace .

D a m a g e t o th e f i b re s u r fa c e m a y s h o w u p b y l e s s e n i n g t h e s i ze o f o r e l i m i n a t in ga l t o g e th e r , t h e b l is t e r s . T h i s te s t is p a r t i cu l a r ly u s e f u l w h en d am ag e cau s e d b y a l -

k a l i t r ea tm en t i s s ev e r e .

1 6 . 1 1 . 2 S w e l l i n g t e s t [ 21 ]

W o o l f i b re i s i m m e r s e d i n a s o lu t io n o f s o d iu m m o n o h y d r o g e n a n d d i h y d r o g e n

p h o s p h a t e a t a p H o f 5 .95 f o r 1 h a t 2 0~ T h e s am p les a r e t h en cen t r i f u g ed t o

r e m o v e t h e e n t r a in e d l iq u o r a n d t h e n w e i g h e d w e t a n d a f t e r w a r d s d r i e d t h o r o u g h l y

an d r ew e ig h e d . T h e r a t i o o f th e w e ig h t o f ab s o r b ed w a te r to t h a t o f d r y f ib r e i .e .

r e t en t i o n o f w a te r w i l l g iv e t h e d eg r ee o f s w e l l i n g . T h e a lk a l i s o lu t io n w i l l r u p tu r e

th e d i s u lp h id e b o n d s i n t h e p o ly p ep t id e ch a in s an d t h u s th e ex t en t o f s w e l l i n g w i l l

g i v e s o m e i d e a o f d a m a g e i n w o o l .

1 6 . 1 1 .3 S o l u b i l i t y t e s t

In t h i s m e th o d th e am o u n t o f w o o l cap ab l e o f b e in g d i s s o lv ed w i th a s o lu t io n ,

w hich rup ture the d i su lph ide cross - l inks , is de termined . Essen t ia l ly it i s a t es t wh ich

d e t ec t s m a in ch a in b r eak ag e cau s ed , m o s t o f ten , b y ac t io n o f ac id s o n w o o l [ 2 1 ,2 2 ] .

1 g w o o l (o v e n d r y ) is t r ea t ed w i th 1 00 m l o f 0 .1 N s o lu t i o n N a O H a t 65~ f o r1 h . T h e s am p le i s t h en r i n s ed w i th 2 l it r e s o f d i s t il l ed w a te r an d d r i ed t o co n s t an t



4 6 4 An a ly s i s an d T e s t i n g i n P r ep a r a to r y P r o ces s es

w eigh t a t 105~ The a lka l i so lub i li ty is then de term ined as the loss in w eigh t o f the

t e s t s p ec im en ex p r es s ed a s p e r cen t ag e . N o r m a l w o o l i s ex p ec t ed t o h av e ab o u t 1 2-1 3 % s o lu b i l i t y an d v a lu es g r ea t e r t h an 1 8% m ay b e t ak en a s s u g g es t i n g t h a t t h e

s a m p l e h a s b e e n d a m a g e d .

In th e Kr a i s - V ie r t e l r eag en t t e s t t h e w o o l i s im m er s ed i n a s o lu ti o n o f am m o n ia

in cau s t i c s o d a [2 3 ]. T h e t e s t en t a il s t im in g o f t h e ap p ea r an ce o f t h e ch a r ac t e r i s ti c

s w e l l i n g s i n t h is reag en t . W h en th e f i b re h as b een d am ag ed w i th ac id , th e t im e f o r

ap p e a r an ce i s d ec r eas ed .

In the u rea -b isu lp h i te so lub i l i ty tes t [24] , wo ol i s t r ea ted wi th a so lu t ion o f u rea

(5 0% ) an d s o d iu m b i s u lp h i t e (3 %) (p H ad ju s t ed t o 7 ) a t 60~ f o r l h an d th en t h e

r e s id u e i s w a s h ed an d d r i ed t il l co n s tan t w e ig h t is o b ta in ed . Ur ea b r eak s t h e h y d r o -

g en b o n d s an d b i s u lp h i t e a t t ack s t h e d i s u lp h id e b o n d s i n w o o l . So lu b i l i ty i n th i s

m e th o d d ep en d s o n t h e w o o l w h ich h ad b een t r ea t ed i n ac id ic o r a lk a l i n e p H.

1 6 . 1 1 .4 S p e e t r o p h o t o m e t r i c t e s t [2 5, 26]

1g s am p le i s ex t r ac t ed w i th 1 0 m l s o lu t i o n co m p r i s in g i s o p r o p an o l : p y r id in e :

w a te r 5 : 5 : 90 . 2 m l o f t h e w o o l ex t r ac t s o lu t i o n is t h en r eac t ed w i th 2 m l o f n in h y -

d r in s o lu t i o n (2 1 . 02 g N aOH, 62 . 4 m l p r o p io n i c ac id an d 3 0 m l d i s t i l l ed w a te r .Af t e r co o l in g 1 25 m l o f m e th y l ce l l o s o lv e an d 1 8.75 n in h y d r in i s ad d ed an d d i s -

s o lv ed an d t h e s o lu t io n i s m a d e u p t o 2 5 0 m l ) in cap p ed t e s t t u b e a t 1 00~ f o r ab o u t

8 m in . Af t e r r eac t i o n th e s o lu t i o n i s m ad e u p t o 5 0 m l an d t h e ab s o r b an ce i s

m eas u r ed i n s p ec t r o p h o to m e te r a t 5 70 n m ag a in s t b l an k n in h y d r in s o lu t i o n t h a t

co n t a in n o w o o l e x t r ac t so lu ti o n . T h e ab s o r b an ce r ead in g f o r t h e ex t rac t f ro m th e

o r ig in a l c l ean w o o l i s ze r o . T h e ab s o r b an ce r ead in g f o r t h e n in h y d r in / w o o l ex t r ac t

r eac t i o n i s d i r ec t l y r e l a t ed to th e d am ag e c au s ed b y s u lp h u r ic ac id . T h e r e s u l t s

co r r e l a t e w e l l w i th b o th a lk a li s o lu b i l i ty an d t en s i le s t r en g th te s t m e th o d s .

1 6 .1 2 D e t e r m i n a t i o n o f D e g r e e o f M e r c e r iz a t io n

T h e e f f ec t o f m er ce r i za t i o n d ep en d s o n t h e co n d i ti o n s o f m er ce r i za t i o n . A q u an -

t i ta t i v e a s s e s s m en t o f t h e d eg r ee o f m er ce r i za t i o n i s ca r r ied o u t m a in ly i n t h ree

d i f f eren t ways i . e . var ia t ion in the mercer ized p roduct , ex terna l appearance ( lus t r e)

an d i n t e r n a l ap p ea r an c e (x - r ay d i ag r am ) e tr [ 2 6] .

1 6 .1 2 .1 D e t e r m i n a t i o n o f d e c o n v o l u t i o n c o u n t [ 27 ]

In th i s m e th o d co t t o n h a i rs a r e cu t in l a rg e n u m b er o f h a i r f r ag m e n t s 0 . 2 m mlo n g . T h ey a r e th en m o u n ted i n l i q u id p a r a f f i n o n a m ic r o s co p ic s li d e , an d t h en



An a ly s i s an d T es t i n g i n P r ep a r a to r y P r o ces s es 4 65

co u n ted t h e p r o p o r t i o n o f f r ag m en t s f ree f r o m tw i s t o n co n v o lu t i o n d u r in g m e r ce r -

i za ti o n . T h e r e s u l t i s ex p r es s ed a s p e r cen t ag e an d is ca l l e d " D eco n v o lu t i o n C o u n t " .

I f t h e f i g u r e i s ab o v e 2 0 , th e f ab r i c i s m er ce r i zed . T h e r a t i o o f t h e tw o s e t s o f d a t a

m a y b e u s e d t o e s ti m a t e t h e d e g r e e o f m e r c e r i z a ti o n . T h e d i s a d v a n t a g e o f t h is

m e th o d i s t h a t th e ex t en t o f d eco n v o lu t i o n i s i n f l u en ced b y t h e m a tu r i t y o f co t t o n

an d b y t h e s t r u c tu r e o f m a te r i a l t h a t i s tw i s t o f t h e y am o r w e av e o f c lo th .

1 6 . 1 2. 2 D e t e r m i n a t i o n o f s w e l l i n g i n d e x [ 2 8]

U n t w i s t in g n u m b e r o f s in g l e y a m c a n g i v e re l ia b l e m e a n s f or e s t im a t i n g d e g r e e

o f s w e l l i n g o f ce l l u lo s e i n n o n - p o l a r l i q u id s s u ch a s ca r b o n t e t r ach lo r id e an d b en -

z e n e . S t r o n g a l ka l i s o l u ti o n a n d c a d o x e n ( c a d m i u m e t h y l e n e d i a m i n e c o m p l e x o f

3 . 6%) a l s o cau s es l a r g e am o u n t o f u n tw i s t i n g . In t h is m e th o d , t h e y a r n t o g e th e r

w i th t h e w e ig h t (0 .8 g ) is h an g ed i n to t h e m eas u r in g cy l i n d e r co n t a in in g s u f f ic i en t

a m o u n t o f s o lv e n t a s to d i p th e u p p e r e n d o f t h e y a m . T h e y a m is th e n a l l o w e d t o

u n t w i s t a n d t h e n u m b e r o f r e v o l u t io n s m a d e b y w e i g h t a r e m e a s u r e d f o r 3 m i n .

U n t w i s t i n g n u m b e r i n s o l v e n tSw e l l i n g i n d ex =

U n t w i s t i n g n u m b e r i n w a t e r

Sw e l l i n g i n d ex i n c r eas es w i th d eg r ee o f m e r ce r i za t i o n . In t h i s m e th o d th e r e is

n o n e c e s s i t y o f u n t re a t e d s a m p l e .

1 6 . 1 2 . 3 B e n z o p u r p u r i n e t e s t

In t h i s m e th o d m er ce r i zed an d u n m er ce r i zed co t t o n s am p les a r e t r ea t ed i n a

0 . 5 % s o lu t i o n o f Be n zo p u r p u r in e f o r 3 0 m in at b o i l i n g tem p er a tu r e . T h e t r ea t ed

s a m p l e s a r e th e n w a s h e d , d r i e d a n d c o m p a r e d v i s u a ll y o r s p e c t r o p h o t o m e t r ic a l l y .

T h e m e r c e r i z e d s a m p l e i s a l w a y s m o r e d e e p l y d y e d t h a n t h e u n m e r c e r iz e d . H o w -

ev e r , i t i s r eco m m en d ed th a t a s t an d a r d s w a tch b e ca l i b r a t ed s o t h a t t h e ac tu a ld e g r e e o f m e r c e r i z a t io n c a n b e a s s u re d .

1 6 . 1 2 . 4 S o d i u m h y d r o x i d e s p o t t i n g t e s t

In t h i s m e th o d th e u n d y ed f ab r i c i s s p o t t ed w i th 3 0% s o lu t i o n o f cau s t i c s o d a

a n d t h e n b o t h m e r c e r i z e d a n d u n d y e d s p o t t e d f a b r i c s a m p l e s a r e d y e d b y u s i n g

B enz opu rpur in e . I f the f abr ic i s fu l ly merce r ized , the spo ts wi l l no t be ev iden t a f te r

d y e in g . On th e o th e r h an d , i f t h e fab r ic i s n o t m er ce r i zed o r s em i - m er ce r i zed , d a r k

s p o t s w i l l b e ev id en t an d t h e d eg r ee o f m er ce r i za t i o n can b e ev a lu a t ed o n co m p ar -

ing the spo ts .



4 6 6 An a ly s i s an d T e s t i n g i n P r ep a r a to r y P r o ces s es

1 6 . 1 2 . 5 G o l d t h w a i t R e d - G r e e n t e s t [ 2 9 ]

In th i s t e s t a m ix tu r e o f r ed an d g r een d i r ec t d y es i s u s ed to co m p ar e t h e m a tu -r i ty o f co t t o n f i b re s am p les . Im m atu r e f ib r e s d y e r ed , an d m a tu r e f i b r e s g r een .

M er ce r i za t i o n i n c r eas es t h e f i b r e ' s a ff in i ty f o r g r een co m p o u n d a n d " cau s t ic i za t io n

n u m b e r " can b e a s s e s s ed r e l a t ed to t h e s t ren g th o f t h e g r een h u e . F ab r i c t rea t ed

w i t h l iq u i d a m m o n i a " u n d e r i n d u s t ri a l m i ll c o n d i t i o n " d y e s r e d.

1 6 . 1 2 . 6 S t a i n i n g t e s t

T h e f i b re i s im m er s ed i n i o d in e s o lu t i o n (2 0 g io d in e i n 1 00 m l o f s t an d a r d KI

s o lu t i o n ) f o r 3 m in an d r i n s ed t h o r o u g h ly . M er ce r i zed co t t o n i s s t a in ed b lu i s h

b l ack an d u n m er ce r i zed co t t o n r em a in s w h i t e . Co t to n f i b re s in t h e y a r n b u n d le can

b e co u n ted u s in g a m ic r o s co p e an d t h e r a ti o o f d y ed to u n d y ed f ib r e s can b e u s ed t o

d e t e r m in e t h e d eg r ee o f m er ce r i za t i o n . T h e i o d in e s o rp t io n v a lu e sh o w s th e la r g es t

i n c r e a s e f o r th o s e s a m p l e s t r e a te d i n li q u id a m m o n i a w i th N H 3 e m o v a l b y e v a p o -

r a t io n , f o l l o w e d b y cau s t ic m er ce r i zed s am p les , an d l a s t b y t h o s e s am p les N H 3

t r ea t ed an d w a te r q u en ch ed . Gen e r a l l y o n ly m in o r d i ff e r en ces i n i o d in e s o r p t io n

v a l u e a r e f o u n d b e t w e e n s a m p l e s m e r c e r i z e d s l ac k o r u n d e r t e n si o n .

In an o th e r m e th o d [30 ] f ab r ic s t rea t ed w i th s ev e ra l co n cen t r a t i o n s o f N aO H a r eim m er s ed i n a m ix tu r e o f 1 .3 g/1 T e lo n F as t Red AF - 3 G 1 5 0% (BA Y) , a lo w m o -

l ecu l a r w e ig h t ac id d y e , C .I Ac id R ed 1 51 an d 1 .4 g/1 Ben zo N ew Blu e G S 1 4 0%

(BA Y), a la rge mole cu la r we igh t d i r ec t dye , C . I. Di rec t Blue 10, l iquor r a t io 70:1 a t

p H 2 u s i n g H2SO 4 f o r 1 0 m in co ld f o l l o w ed b y w as h in g o f f . Un t r ea t ed co t t o n i s

s t a in ed r ed an d b eco m es p r o g r es s iv e ly b lu e r w i th i n c r eas e in N a OH co n cen t r a t i o n .

1 6 . 1 2 . 7 B a r i u m a c t i v i t y n u m b e r [ 3 1 - 3 3 ]

Mer ce r i zed s am p le ab s o r b s b a r iu m h y d r o x id e ( a lk a l i ) t o a g r ea t e r d eg r ee t h an

s o d iu m h y d r o x id e an d f r o m p r ac t i ca l p o in t o f v i ew , b a r iu m h y d r o x id e i s m o r e ea s y

to e s t im a te . T h e r a t i o o f u p tak e f o r t h is r eag en t h as b een r e f e r r ed t o b a r iu m ac t iv i t y

n u m b er .

2 g m er ce r i ze d an d u n m er ce r i zed s am p les a r e p l aced s ep a r a t e ly in tw o co n i ca l

f l a s k co n t a in in g 3 0 m l o f N / 4 b a r iu m h y d r o x id e an d l e f t f o r 2 h o r p r e f e r ab ly

o v e r n ig h t . 1 0 m l o f c l ea r s o lu t i o n i s w i th d r aw n an d t i tr a t ed ag a in s t N / 1 0 HC1 u s in g

p h e n o lp h th a l e in a s i n d i ca to r . A b l an k t i tr a t io n i s a l s o ca r ri ed o u t o n th e m e as u r ed

b a r iu m h y d r o x id e s o lu t io n u s in g Meth y l R ed a s i n d ica to r .

b - sBa r iu m ac t i v i ty n u m b er -- ~ x 1 00

b - u




wh e r e , b = m l r e q u i r e d f o r b l a n k t e s t,

s = m l r e q u i r e d f o r m e r c e r i z e d c o t to n ,

u - m l r e q u i r e d f o r u n m e r c e r i z e d c o t t o n .

F o r e x a c t e s t i m a t i o n , c o r r e c t io n s h o u l d b e m a d e f o r t h e m o i s t u r e r e g a i n o f t h e

s a m p l e . B a r i u m a c t i v it y n u m b e r o f u n m e r c e r i z e d c o t t o n i s c o n s i d e r e d a s 1 00 a n d

s e m i - m e r c e r i z e d c o t t o n r a n g e s b e t w e e n 1 15 to 1 3 0 a n d th a t fo r c o m p l e t e l y m e r c e r -

i z e d c o t t o n i s a b o u t 1 5 5 .

1 6 . 1 2 .8 D e t e r m i n a t i o n o f l u s tr e [ 34 , 35]

P u l f r i c h p h o t o m e t e r , t h e G o r e z G l a r i m e t e r c o m p a r a t i v e g l a s s m e t h o d a n d m i -

c r o s c o p i c e x a m i n a t i o n o f c r o s s - s e c ti o n o f fi b re a r e th e q u a l i t a ti v e m e t h o d s f o r t h e

a s s e s s m e n t o f d e g r e e o f m e r c e r iz a t io n .

M e r c e r i z a t i o n i n c r e a se t h e l u s tr e a n d r e d u c e s t h e a x ia l r a t io ( F ig . 1 6 -3 ) . M i c r o -

bI

B e f o r e m e r c e r i z a t i o n A f t e r m e r c e r i z a t i o n

F i g u r e 1 6 -3 . C r o s s - s e c t i o n o f c o t to n f ib r e b e fo r e a n d a f t e r m e r c e r i z a t i o n .

s c o p i c e x a m i n a t i o n s h o w s t h a t t h e c o r s s - s e c ti o n o f t h e c o tt o n f i b re c h a n g e s f r o m

e l ip t i c a l t o c i rc u l a r f o r m d u e t o m e r c e r i z a t i o n . T h i s c a n b e m e a s u r e d a s a r a t io o f

t w o a x e s ' a ' a n d ' b ' . T h e a x i al r a t io ( a /b ) o f u n m e r c e r i z e d c o t t o n is a b o u t 2 .2 to

2 . 6, w h e r e a s t h a t o f m e r c e r i z e d c o t t o n is a b o u t 1 .5 to 1 .6 . C a u s t i c m e r c e r i z e d

s a m p l e s a p p e a r t o g i v e s u p e r i o r l u s tr e t h a n a m m o n i a t r e a te d f i b re .T h e m e a s u r e m e n t o f s p e c u l a r r e f l e c t a n c e i s c o n s i d e r e d a s a n a c c u r a t e e v a l u a -

t io n o f l u s tr e . L u s t r e c a n b e d e t e r m i n e d f r o m r e f l e c ta n c e m e a s u r e m e n t s w i t h in c i -

d e n t l i g h t i n c l i n e d a t 4 50 , t h e r e f l e c t e d l i g h t is m e a su r e d e i t h e r p e r p e n d i c u l a r l y t o

t h e su r f a c e o f t h e m a t e r i a l ( d i f f u se r e f l e c t a n c e ) o r v i e w e d a t 4 5 ~ sy m e t r i c a l l y t o t h e

i n c i d e n t l i g h t ( sp e c u l a r r e f l e c t a n c e ) . Lu s t r e i s t h e r e f o r e d e f i n e d b y th e c o n t r a s t

r a t i o o f t h e sp e c u l a r t o d i f f u se r e f l e c t a n c e [ 3 6 , 3 7 ] .

1 6 . 1 2 . 9 x - r a y a n a l y s i s

X - r a y p h o t o g r a p h o f n a t i v e c e l lu l o s e ( u n m e r c e r i z e d ) r e v e a l s th e p r e s e n c e o f

t w o a r c s c l o s e t o g e t h e r a n d in s i d e th e p r o m i n e n t 0 0 2 a r c. T h e s e r e f l e c t i o n s a r e



46 8 Ana lys i s a nd T e s t ing in P r e pa r a to r y P r oc e sse s

ram

f r om 101 p la ne a nd 101 p la ne , t he l a t t e r be ing n e a r e r the c e n tr e o f t he pho tog r a ph .

Th e y a r e no t a s in t e nse a s 0 0 2 a rc s . I n c a se o f c om ple te ly m e r c e r i z e d o r re ge ne r -a t e d c e l lu lose , X - r a y pho to g r a ph show s a c ha nge in pos i t ion o f two sho r t e r a rc s .

Th e 101 a rc i s m uc h nea re r to 002 a rc and 101 a rc is nea re r the cent re of the photo -

g r a ph . On the ba s i s o f t h i s e s t im a t ion s i t i s e s t im a te d tha t m e r c e r i z ing e f f i c i e nc y

s e l d o m e x c e e d s 6 0 - 70 % f o r y a m a n d 3 5 - 4 0 % f o r c lo th .

1 6 . 1 2 . 1 0 I n f r a - r e d a n a l y s i s

De te r m ina t ion o f in f r a - r e d c r ys t a l l i n i ty inde x a t d i f f e r e n t wa ve le ng ths ( 1429

cm-~/893 c m -~) by the u sua l bas e l ine tech niqu e can be u sed [38 ]. W he n ce l lu lose -

I I sam ples a re con s ide red , the 1372 cm-~/2900 cm -~ ra t io i s m ore re l iab le in dex [39 ,

40 ] . A r a p id m e tho d f o r e s t im a t ion o f the de g r e e o f m e r c e r i z a t ion ha s be e n d e ve l -

ope d us ing a ne a r I R d i f f use r e fl e c t ion t e c h n ique [41 ] .

1 6 .1 3 E v a l u a t i o n o f W h i t e n i n g E f f i c ie n c y o f O p t i c a l B r i g h t e n e r s

The e s t im a t ion o f op t i c al w h i t e ne r s in subs t r a t e i s r e a l ly a d i f f ic u l t p r ob le m , bu t

the qua l i t a t ive a n d qua n t i t a t ive e s t im a t ion o f f luo r e sc e n t b r igh te ne r in so lu t ion by

e xa m ina t ion o f a bso rp t ion a nd /o r e m is s ion spe c t ra ha ve be e n de ta i l e d [42 - 46] . S ince

the b r igh te n e r w i l l d i ff e r i n subs ta n t iv i ty f o r a pa r t ic u la r sub s t r a te w i th d i f f e r e nc e sin the i r c he m ic a l s t r uc tu r e , c os t c om pa r i son s o f pe r f o r m a nc e c a n on ly be ba se d

upo n e v a lua t ion o f the tr e a t e d subs t r a te s . Va r ious t e c hn ique s f o r suc h e va lua t ion

ha ve be e n de sc r ibe d [46- 51 ] .

1 6 . 1 3 . 1 V i s u a l a s s e s s m e n t

V i s u a l a s s e s s m e n t o f a w h i t e o b j e c t i s b a s e d o n a c o m p a r i s o n o f t h e t es t s a m p l e

w i t h a s t a n d a r d s a m p l e . A v i e w i n g a n g l e o f 4 5 ~ s g e n e r a ll y r e c o m m e n d e d a n d t h e

pos i t ion o f the sa m ple s a r e c ha nge d se ve r a l tim e s d u r ing the t e st . Ou t o f m a ny

w h i t e s c a le s , C i b a - G e i g y ' s " C o t t o n w h i t e s c a l e " o c c u p i e s a p r o m i n e n t p o s it i o n

[52].

1 6 . 1 3 . 2 E x t r a c t i o n m e t h o d

Ge n e r a l ly op t i c a l b r igh te ne r s on c o t ton a r e e x t r a c te d f r om the f a b r ic by su i t a b le

so lve n t l ike py r id ine . The a bso r ba nc e o f the e x t r a c t e d so lu t ion o f op t i c al b r igh te n -

e rs o f u n k n o w n c o n c e n t r a t io n is d e t e rm i n e d b y u s i n g a u v - s p e c t ro p h o t o m e t e r , a n d

by r e f e r r ing the c a l ib r a t ion g r a ph , t he unk now n c on c e n t r a t ion i s de t e r m ine d . Op t i -

c a l b r igh te ne r s c a n a l so be de te r m ine d by e x t r a c tion wi th a lka l ine c a do xe n so lu t ionwi th in n a r r ow l im i t s [53] a nd w i th re l a t ive ly l a r ge e rr o r s (> 20 % ) in the uv r a nge




[ 5 4 ]. T h i s m u s t p l a c e s o m e d o u b t o n re s u l t s o f f l u o r e s c e n t b r i g h t e n i n g a g e n t c o n -

c e n t r a t i o n s d e t e r m i n e d i n t h is w a y . A s i m i l a r te c h n i q u e i s al so u s e d t o d e t e r m i n ef l u o r e s c e n t b r ig h t e n i n g a g e n t s o n n y l o n a n d a c e t a t e fi b re s [ 5 5] . A m - c r e s o l - m e t h a -

no l mi x t u re i s u s e d a s s o l ve n t f o r ny l on f i b r e s a nd D MF fo r t he a c e t a t e f i b r e s .

E x t r a c t i o n w i t h a D M F - w a t e r m i x t u r e i s r e c o m m e n d e d f o r c e ll u l o s ic f i b re s .

1 6 .1 3 .3 I n s t r u m e n t a l a s s e s s m e n t

T h i n - l a y e r c h r o m a t o g r a p h y , t r i st u m u l u s f il te r p h o t o m e t e r a n d s p e c t r o p h o t o m -

e t e r ar e t h e m o s t p o p u l a r t e c h n i q u e s f o r s e p e ra t io n , i d e n t i fi c a t io n a n d q u a n t i t a ti v e

a n a l y s i s o f f l u o r e s c e n t b r i g h t e n i n g a g e n t s , a lt h o u g h s o m e o t h e r i n s t r u m e n t a l te c h -

n i q u e s h a v e b e e n d e v e l o p e d [ 5 6 ]. S p e c t r o p h o t o m e t e r s s im p l y m e a s u r e s p e c tr a l r e -

f l e c t a n c e , f r o m w h i c h t r i s t u m u l u s v a l u e s a r e c a l c u l a t e d o n t h e b a s i s o f s p e c t r a l

e n e r g y d i s t ri b u t i o n o f th e l i g h t s o u r c e a n d t h e C . I. E . s p e c t r a l t ri s t u m u l u s v a l u e s

fun c t i on . T he L * , a* , b* va l ue s fo r t he s t a nda rd r e f e r e nc e s ub s t r a te a nd t he s a mp l e

a re de t e rmi ne d . The fo rme r va l ue s a r e s ubs t r a c t e d f rom t he l a t t e r t o ge t A L * , A a *

a n d A b * v a l u e s . T h i s d e t e r m i n e s t h e w h i t e n e s s a n d t o n a l d i f f e re n c e s . T h e r e s u l t s

o b t a i n e d b y t h i s m e t h o d a r e n o t a l w a y s w i t h f u l l a g r e e m e n t w i t h t h e r e s u l t s o f

s ub j e c t i ve e va l ua t i on , a nd t he r e fo re i t i s u s e d a s a n a ux i l i a ry me t h od , e s pe c i a l l y i nt h e d e t e r m i n a t i o n o f th e c o n c e n t r a t i o n o f t h e b r i g h t e n i n g a g e n t o n f i b r es .

1 6 .1 4 D e t e r m i n a t i o n o f th e D e g r e e o f H e a t - s e t t in g

1 6 . 1 4 . 1 S h r i n k a g e t e s t

N o r m a l l y a s q u a r e a r e a i s d r a w n o n t h e h e a t - s e t m a t e r i a l a n d m e a s u r e d . T h e

m a r k e d c l o t h i s b o i l e d i n s o f t w a t e r i n th e w a s h i n g w h e e l f o r 3 0 m i n , c e n t r i f u g e d

a n d a i r d r i ed . T h e d i m e n s i o n s o f t h e s q u a r e a r e m e a s u r e d w i t h o u t i r o n i n g t h e d r ie d

fa b r i c a nd t he s h r i nka ge i s de t e rm i ne d . A w e l l s e t f a b r ic s hou l d no t s ho w m ore t ha n

1 % r e s id u a l s h r i n k a g e .

16 . 14 . 2 C r e a s e - r e c o v e r y a n g l e

T h e d e t e r m i n a t i o n o f c r e a s e re c o v e r y a n g l e b e f o r e a n d a f t er h e a t - s e t ti n g o f t h e

f a b r ic i s d o n e . T h e e x t e n t o f c r e a s e - r e c o v e r y o f h e a t - s e t f a b ri c b e f o r e a n d a f te r

s e t ti n g a t a n d a b o v e 1 7 0 -1 7 5 ~ w i l l g i v e i d e a o f t h e d e g r e e o f h e a t - s e t ti n g .

1 6 . 1 4 . 3 A s s e s s m e n t o f h a n d l e

A s s e s s m e n t o f h a n d l e b e f o r e a n d a f te r s e t ti n g g i v e s a n id e a o f th e d e g r e e o f

he a t - s e t t i ng . I n ge ne ra l , f a b r i c be c o m e s s t i f f a f t e r he a t - s e t t i ng . S t i ffne s s i s m e a -s u r e d b y b e n d i n g l e n g t h a n d c o m p a r e d w i t h t h a t o f t h e u n s e t fa b r ic . T h e n a r r o w e r



4 7 0 An a ly s i s an d T es t i n g i n P r ep a r a to r y P r o ces s es

th e d i f f e r en ce o f b en d in g l en g th b e tw e en th e s e t an d u n s e t f ab r ic s , t h e b e t te r t h e

set t ing.

1 6 . 1 4 . 4 I o d i n e a b s o r p t i o n m e t h o d

T h e d eg r ee o f h ea t - s e t t i n g o f p o ly e s t e r f ab r i c s can b e co r r e l a ted w i th t h e i r i o-

d in e ab s o r p t i o n v a lu e . Hea t - s e t t i n g u n d e r i n d u s t r i a l co n d i t i o n s i n a t au t f o r m r e -

d u ces t h e am o r p h o u s co n t en t o f s y n th e t i c f i b r e s . So , t h e r e w i l l b e a d ec r eas e i n

iod ine sorp t ion and increase in c r i t i ca l d i s so lu t ion va lue [57] .

1 6 .1 5 D e t e r m i n a t i o n o f B i o d e g r a d a b i l i t y o f S u r f a c t a n t s [ 58 ]

T h e e f f i c i en cy o f a s ew ag e t r ea tm en t i s o f t en ex p r es s ed a s t h e p e r cen t ag e r e -

m o v a l o f th e B O D , l e s s o f te n i n te r m s o f C O D r e m o v a l . D i v i d i n g t h e p e r c e n t

r e m o v a l o f th e s u r f a c ta n t b y t he p e r c e n t re m o v a l o f t h e B O D o r C O D g i v e s th e

b io d eg r ad ab i l i t y i n d ex o f t h e s u r fac t an t .

T h e p r o c e d u r e f o r a l k y l b e n z e n e s u l p h o n a t e s ( A B S ) a n d l in e a r

a lk y lb en z en es u lp h o n a t e s g iv en b y th e s o ap an d d e te r g en t a s s o c ia t i o n i n v o lv es b o th

a p r e s u m p t iv e an d a co n f i r m a to r y t e s t.

In t h e p r e s u m p t iv e t e s t, a n u t r i en t m ed iu m , t o w h ich 3 0 m g / 1 t e s t s u r fac t an t h as

b een ad d ed , i s i n o cu l a t ed w i th m ic r o - o r g a n i s m s in a cu l t u r e f la s k an d ae r a t ed b y ar ec ip r o ca t i n g s h ak e r a t 12 8 tw o - f o u r i n ch s t r o k es / m in a t 2 5 + 3 ~ Af t e r tw o 72 h

ada p t ive t r ans fer s , in wh ich 1 ml o f the 72 h cu l tu re i s t r ans fe r red to 100 ml o f a

f r e s h n u t r i en t m ed iu m p lu s s u r f ac t an t , s am p les a r e tak en a t ze ro t im e , i .e . im m ed i -

a t e ly a f te r i n o cu l a t i o n an d m ix in g an d o n 7 th an d 8 th d ay s . A b l an k u n d e r t h e s am e

co n d i t i o n s b u t w i th o u t t h e s u r f ac t an t i s ca r r i ed o u t s i d e b y s id e . T h e s am p les a r e

th en t e s t ed f o r th e ac t i v e co n t en t b y t h e M eth y l en e B lu e m e th o d . I f an a ly s i s is n o t

d o n e im m ed ia t e ly , 1 m l f o r m a ld eh y d e p e r 1 00 m l s h o u ld b e ad d ed a s p r e s e r v a t i v e .

I f t h e p e r cen t d eg r ad a t i o n i s l e ss t h an 80, th e s am p le i s n o n - b io d eg r ad a b l e . I f ab o v e

90, the sam ple i s b iod egra dab le and in th i s case no fu r ther tes t i s nece ssary . A va lue

o f 80 - 90% in d i ca t e s t h e n eces s i t y o f ca r r y in g o u t a co n f i r m a to r y t e s t . A l th o u g h

p r es u m p t iv e t e s t i s s im p le an d i n ex p en s iv e i t s u f fe r s f r o m th e d i s ad v an t ag e i n t h a t

i t t akes 14 days in a l l and tha t i t does no t mea sure r a te per day o r per hour , bu t on ly

to ta l d eg r ad a t i o n i n o n e w eek .

In t h e co n f i r m a to r y t e s t , a c t i v a t ed s lu d g e f r o m a d o m es t i c s ew ag e t r ea tm en t

p l an t , t e s t s u r f ac tan t (2 0 r ag / l) an d s y n th e t ic s ew a g e o f co m p o s i t i o n



A na l y s i s a nd Te s t i ng i n P re pa ra t o ry P roc e s s e s 471

Gluc ose 13 .0 g

Ne ut r i en t 13 .0 g

B e e f e x t r a c t 13 .0 g

K3HPO4 13.0 g

(NH4)2SO 4 2.5 g

Ta p w a t e r 1 l it r e

a r e mi xe d i n a s pe c i a l l y de s i gne d ve s s e l , b rough t t o a s t e a dy s t a t e a nd a e r a t e d fo r

23 h. A f t e r 1 h s e t tl i ng , s upe m a t a n t l i qu i d i s w i t h d ra w n a n d t he s a me a m oun t i s

r e p l e n i s h e d w i t h s yn t he t ic s e w a ge c on t a i n i ng 20 mg / 1 s u r f a c ta n t . Th i s i s r e pe a t e d

f o r a m i n i m u m o f 1 5 d a y s a f te r w h i c h t h e a c t iv e c o n t e n t i s d e t e r m i n e d b y M e t h y l -

e n e B l u e m e t h o d . T h e c o n f i r m a t o r y m e t h o d s u f fe r s f ro m t h e d i s a d v a n t a g e t h a t t h e

t e s t i ng t i me e xc e e ds t he no rma l r e t e n t i on t i me i n a n a c t i va t e d s l udge s ys t e m i n

s e w a ge p l a n t s .

1 6 . 1 5 . 1 M e t h y l e n e B l u e m e t h o d

A 10 m l a l i quo t o f a s o lu t i on c o n t a i n i ng 0 . 625 g o f 10 0 % a c t i ve c on t e n t i n 500

ml i s p i pe t t e d i n a 10 0 ml g r a dua t e d g l a s s s t oppe re d c y l i nde r a n d 25 ml o f a que o us

m e t hy l e ne b l ue i nd i c a t o r ( The i nd i c a t o r is p r e p a re d by p i pe t t i ng 10 ml o f 0 . 3%s o l u t i on o f m e t hy l e ne b l ue hy droc h l o r i de i n to 50 0 ml w a t e r , a dd i ng 12 g c onc e n -

t r a t e d H 2S O 4 a nd 50 g Na2SO 4a nd t he n d i l u t i ng t o 1 l it re ) a nd 15 ml o f c h l o ro fo rm

a dde d . The s o l u t i on i s t he n t i t r a t e d w i t h 0 . 0 0 4 M c e t y l py r i d i n i um b romi de , s ha k -

i ng mi x t u re v i go rous l y fo r 3 mi n a f t e r e a c h a dd i t i on . A s t he t i t r a t i on c on t i nue s

t he re is a s l ow t r a ns f e r o f b l ue c o l ou r f rom c h l o ro fo rm t o a que o us l a ye r . W h e n t he

c o l ou r o f the t w o l a ye r s ha s e q ua l i s e d t he e nd po i n t i s r e a c he d .

A c t i ve i ng re d i e n t , % = a x b x m x 5W

w he re , a = ml o f t i tr a n t c on s um e d ,

b = mol a r i t y o f a bove s o l u t i on ,

m = m o l e c u l a r w e i g h t o f a c ti v e i n g r e d ie n t , a n d

w = w e i g h t o f sa m pl e i n g.



472 Analys is and T est ing in Prepara to ry Processes

R E F E R E N C E S

1 D . T . Co u s in eau , New Ap p r o ach es an d Dev e lo p m en t s f o r B leach in g o f

Ce l lu lose and i ts Blends , Am er ican Ho echst Corpora t ion .

2 J . E . Ne t t les , Handbo ok of Ch em ica l Spec ia l t ies , John Wiley and Sons , New

York, 1983.

3 AS TM Design a t ion : D 1909-68 (1973).

4 M .W . R utenberg, "S ta rch and i ts M odif ica t ions" in Handbook of water -so lub le

Gu m s and Resins , Robe r t I ., Davidson , Ed . , M cGraw -Hil l , N ew Y ork , 1980.

5 B r i t i sh Standard Han dboo k No. 11 (1963) 485 .

6 AA TC C te s t m e th o d 97, USA.

7 DI N 5 4 2 85 , Ge r m an y .

8 DI N 5 4 2 78 , Ge r m an y .

9 "S tan d a r d Dr av es W e t t in g Te s t " AATC C Meth o d No . 1 7 ( 1974 ).

10 E . R. Tro tman , Tex t i le Scour ing and Bleach ing , Gr i ff in , London , 1968.

11 D .A . C libben s and A. Geake, J . Tex ti le Inst . , 19 (1928) T 77.

12 D. A. C libben s and A. A. Lit t le , J . Tex ti le Inst. , 27 (1936) T 285.13 Sh ir ley Inst i tu te Bu llet in , M anch ester , Englan d, 39 (1966) 29.

14 O. A. Ba tt ista , Industr . Eng. Chem . Anal . Edn. , 16 (1944) 351.

15 A. Ag ster , M ell iand Tex ti lber . , 54 (1973) 497.

16 S . R. Karm aka r and W. B. Achw al , Proc . 13 th Tech . Conf ., ATIRA, B TR A,

SITRA, Ahmedabad , (Dec 1972) .

17 S . R. Karm aka r and W . B. Achw al , J. Tex t i le Assocn . , (1972) 23 .

18 C. Ear land and D. J . Raven , Exper iments in Tex t i le and F ibre Chemis t ry ,

Lond on , B ut te rwor ths (1971 ) 134 .

19 W . G. Crew ther and T . A. Press ley , W ool S c ience Rev ., No . 26 (1964) .

20 K. Von Al l~w orden , Z . Angew . Chem . , 29 (1916) 79 .

21 E. F. Else w orth , J . Soc. Dy ers Colou rists , 68 (1952) 207.

22 E. F. Elsew orth , J . Te xti le Inst . , 52 (1961) 8678.

23 P.K . K rais, H. M erke r t and O. Vier tel , Forsch. Inst. Text . Ind. Dresde n, 1933,

H 14 and 15.

24 An on. , J . Tex ti le Inst . , 52 (1961) 8681.25 C. W an g and M. T. Pail thorp e, Texti le Res. J ., 57 (12) (1987) 728.



An alys i s and Tes t ing in Preparatory Pro cesses 473

26 H. Herm anu tz , H. Her l inge r and D. Bech ter , Text i l Praxis , 49 (1994) 495.

27 J . T . Ma rsh , Merc er iz ing , C hap m an and Hal l , Lond on, 1951, p 39.28 J . H. Co rr et al , Te xt i le Re s. J ., 32 (1962) 1041.

29 P. Vo nh ore , Int . Te xt i le Bull . (Dy g/Ptg. /Fin g.) (1982) 104

30 S. Dugal , U. Denter and E. Schol lmeye r, Me ll iand Text i lber., 64 (July 1983) 494.

31 S .M . N eale , J . Tex t i le Ins t. , 22 (1931) T 349.

32 S . M. Edels te in , Am er . D ye s tu ffR ep . , 25 (1936) 186, 545 and 724.

33 S . M . Ed els te in , Ra yon and Synthet ic Text i les , 32 (10) (1951) 62 .

34 M one n, J . Tex t i le Ind . , 49 (1934) 257.

35 Desbleds , Dyers , 64 (1930) 515.

36 L. Fo urt and A. M. S ook ne, Text i le Res. J ., 21 (1951) 469.

37 L. Fou r t and A. M. Sookn e, Am er . Dy es tu ffR ep . , 43 (1954) 304.

3 8 R. T . O 'C on no r e t a l, Anal . Chem . , 29 (1957) 998.

39 M. L . N elson and R. T . O 'Co nn er , J . Appl . Polym. Sci ., 8 (1964) 1311.

40 M. L . N elson and R. T . O 'C on ne r , J . Appl . Polym . Sci ., 8 (1964) 1325.

41 S. Gh osh an d D. Dilan ni , J . Te xt i le Inst ., (1944) 308.

42 Szek ely , M agy av, Text i lt ech , 20 (1968) 437.43 Z io lko w sky , Sei fen Oele Fet te W achse , 95 (1969) 705.

44 Szek ely , Text . Ku tato In tezet , 19 (1969) 35 .

45 Pes tem er , M el l iand Tex t i lber . , 51 (1970) 75 .

46 Sol jac ic , Tex t i lveredlung , 6 (1971) 796.

47 S tensby, Soa p Chem . Spec. , 43 (5) (1967) 84.

48 M ieuw enh uis , J . Am er . Oi l Che m. Soc. , 45 (1968) 37.

49 M ecke l , Me l l iand Text i lber ., 50 (1969) 859.

50 Laube , Te xt i lveredlung , 5 (1970) 418.

51 An der s , J. Am er, Oil Ch em . Soc. , 48 (1971) 80.

5 2 C i b a - G e i g y R e v i e w , 1 9 7 3 / 1 .

53 W .B. Achw al and A. K. Na rkar , Text i lveredlung, 7 (1972) 19.

54 I . Ru szn ak , I. Ta ncz os an d P. Sal lay, Ko l . Ert . , 15 (1973) 2.

55 L. S . Kr asn ov ska y and V. T. Ku drya shov a, Khim. Volok. , 14 (1972) 68.

56 J . Gasp ar ic , Che m icke Lis ty , 63 (1969) 1363.

57 An on . , Int . Dy er, (19 Feb 1965).58 N. F . Desai , Colo urage (Sept 1980) 62 .



This Page Intentionally Left Blank



S U B J E C T I N D E X

A b a c a , 2

A b s o r b a n c y , 4 5 2A c c e l e r a t e d b l e a c h i n g o f b l e n d s , 1 67

A c c e l e r a t e d h y p o c h l o r i t e b l e a c h i n g ,

- -- , b y s t e a m i n g m e t h o d , 1 67

- -- , c o n j u n c t i o n w i t h H202, 166

- -- , e l e v a t e d t e m p e r a t u r e , 1 6 6

- - - , i n d a n g e r z o n e , 1 6 6

- -- , in p r e s e n c e o f a d d i t i v e s , 1 6 7

A c e t a t e f i b r e s,

- - , m a n u f a c t u r i n g o f , 3 5

A c i d h y d r o l y s i s o f c o t t o n , 3 4 6

A c r i l a n , 1 8 1

A c r y l i c f i b r e s , 3 4

A c t i o n o f a c id s , 3 5 0

- - - , o n c o t t o n , 3 4 5

A c t i o n o f a l k a l i e s ,- - - , o n c o t t o n , 8 6 , 3 4 6

, , ny lon , 31

, , p o l y e s t e r , 3 5 7

, , s i lk , 86, 356

, , w o o l , 8 6 , 3 5 5

A c t i v a t e d s l u d g e p l a n t , 3 8 5

A c t i v a t o r s f o r ,

- -, c h l o r i t e b l e a c h i n g , 1 8 3 - 1 8 5

- -, H 2 02 b l e a c h i n g o f s i l k , 1 7 9

, , w o o l , 1 7 4

- - , p e r a c e t i c a c i d , 1 8 9

A d v a n t a g e o f b l e a c h i n g w i th ,

. . . . , c h l o r i t e , 1 8 7

. . . . , h y p o c h l o r i t e , 1 67

. . . . , p e r a e e t i c a c i d , 1 91

. . . . , p e r o x i d e , 1 81

A i r p o l l u t i o n , 3 7 0

A i r i n k i e r s , 3 4 6 , 3 4 8A l k a l i c e l l u l o s e , 2 8 5

A l k a l i e a r t h m e t a l , 8 8qq,

A l l w o r d e n r e a c t i o n , 4 6 3

A l p a c a , 2

A m i n o a c i d c o n t e n t,

- - - , on s i lk , 12 ,15

, , w oo l , 12

A m m o n i a m e r c e r iz a t io n , 3 0 9

A m o r p h o u s r e g io n , 4

A m p h o t e r i c s u r f a ct a n ts , 9 8

A m y l a s e , 6 9 , 4 1 8 ,4 1 9

A m y l o p e c t i n , 7 0

A n a l y s i s o f n o n - c e l l u l o s i c r e s i d u es ,

. . . . , a s h c o n t e n t , 4 4 3

. . . . , c a l c iu m a n d m a g n e s i u m , 4 4 4

. . . . , i r o n a n d c o p p e r , 4 4 5

. . . . , s i l ic a t e a n d p h o s p h a t e , 4 4 4

A n a l y s i s o f w a t e r ,

- - -, c a l c i u m h a r d n e s s , 4 4 3

- -- , m a g n e s i u m h a r d n e s s , 4 4 3

- - - , s u s p e n d e d m a t t e r , 4 4 2

--- , tem porary and permanent hardness , 443

- -- , to t a l h a r d n e s s , 4 4 2

- - -, to t a l s o l u b l e s a l t, 4 4 2

A n i m a l f i b r e s , 2

A n i o n a c t iv e s u b s t a n c e s , 9 4

A n t i - c h l o r tr e a t m e n t , 1 6 4 , 1 6 6

A n t i - r e d e p o s i t i o n a g e n t s ,

- - - , C M C s t r u c t u r e , 1 0 2



4 7 6 S u b j e c t I n d e x

- - - , P V P s t r u c t u r e , 1 03

A O X , 1 6 8 , 3 7 2A s s i s t a n t s , k i e r b o i l i n g , 1 3 4

A v a i l a b l e c h l o r i n e , 1 6 5 , 4 5 5

A u x i l i a r y p r o d u c t s in ,

- - - , e m u l s i f y i n g b a t h , 1 0 1 , 1 0 3 , 1 0 6

- - - , m e r c e r i z i n g l i q u o r , 2 5 0

- - - , k i e r b o i l i n g , 9 0 , 91

B a r i u m a c t iv i ty n u m b e r , 4 6 6

B a s t f i b r e s , 1 6

B a t c h e q u i p m e n t ,

- -, c o t t o n d e s i z i n g , 7 9

- - , - , s c o u r i n g , 1 3 2

- -, -, b l e a c h i n g , 2 1 7

B a t t r i c e m a c h i n e , 1 4 8

B e c o f l e x r o ll e r, 2 5 5B e c c o J - B o x , 1 3 8, 2 2 4

B e n - b l e a c h s y s t e m . , 2 3 0 - 2 3 2 , 3 4 0

B e t a - a l k o x y r e a c t i o n , 3 4 7

B i c o m p o n e n t f i b r e s , 4 3

B i o - d e g r a d a t i o n , 3 8 0 , 3 8 4

B i l a t e r a l s t r u c t u r e o f ,

- - - , co t t on , 11

- - - , w o o l , 1 0

B i o p l a s t i c f i b r e s , 4 3

B i o - p o l i s h i n g , 4 2 8

B i o - t e c h n o l o g y , 4 1 8

B l e a c h i n g a g e n ts ,

- -, c h l o r i n a t e d t r i s o d i u m p h o s p h a t e , 1 63

- - , c l a s s i f i c a t i o n o f , 1 6 1

- - , e m u l s i o n , 1 7 8- - , ox id i s ing , 16 1 , 16 8 , 18 8

- -, l i t h iu m h y p o c h l o r i t e , 1 63

- -, p e r o x y g e n d e r i v a t i v e s , 1 9 6- - , r e d u c i n g , 1 9 2

B l e a c h i n g o f,

- - , ace t a t e , 18 0

- - , ac ry l i c s , 18 0

- - , b l e n d e d f a b r i c s , 2 0 3 - 2 9 9

- -, c o t t o n , 1 6 1 , 1 6 8 , 1 7 3 , 1 8 3 , 1 90

- - , j u t e , 19 6 -20 1

- - , l i n e n , 2 0 1 , 2 0 2

- - , ny lon , 18 4 , 19 5

- - , p o l y e s t e r , 1 8 4

- -, p o l y v i n y l a l c o h o l , 1 8 6

- -, p o l y v i n y l c h l o r i d e , 1 85

- -, r e g e n e r a t e d f i b r e s , 1 8 0

-- , s i lk , 178

- - , w e f t - k n i t t e d c o t t o n , 1 9 3 , 1 9 4 , 2 0 9- - , w o o l , 1 9 2 - 1 9 4

B l e a c h i n g o f b l e n d e d f a b ri c s,

. . . . , a c e t a t e / c e l lu l o s e , 2 0 8

. . . . , a c r y l i c / c e l lu l o s e , 2 0 7

. . . . , a c r y l i c / w o o l , 2 0 6

. . . . , n y l o n / c e l l u l o s e , 2 0 6 , 2 0 7

. . . . , n y l o n / w o o l , 2 0 7

. . . . , p o l y e s t e r / c o t t o n , 2 0 3 - 2 0 6

. . . . , p o l y e s t e r / l i n e n , 2 0 8

. . . . , p o l y e s t e r / w o o l , 2 0 6

. . . . , v i s c o s e / c o t t o n , 2 0 9 , 2 1 0

. . . . , w o o l / v i s c o s e , 2 0 9

B l e a c h i n g o f c o l o u r e d w o v e n g o o d s , 1 6 6

B l e a c h i n g e q u i p m e n t , b a t c h ,

- - , -, j i g g e r s , 2 1 9- - , - , r ope , 221



S u b j e c t I n d e x 4 7 7

, , sp i ra l j e t , 22 2

- - , - , w i n c h e s , 2 2 0

B l e a c h i n g e q u i p m e n t , s e m i - c o n t in u o u s ,

- - , - , p a d - b a t c h , 2 2 2

- - , - , p a d - j i g , 2 2 4

- - , - , p a d - r o l l , 2 2 3

B l e a c h i n g e q u i p m e n t , c o n t i n u o u s r o p e ,

, , 3 - s t a g e J - B o x , 2 2 5

, , 2 - s t a g e J - B o x , 2 2 6

- -, - - , D u B e c s y s t e m , 2 2 8

, , F M C W e t b o t t o m , J- B o x , 2 2 8

, , s i n g l e s t a g e p l a n t , 2 2 6

Bleaching equipment, continuous open-width,

, , B e n - b l e a c h , 2 3 0

, , c o m b i - s t e a m e r s , 2 3 6 - 2 3 7

, , m u l t i l a y e r c o n v e y e r , 2 3 5

, , P K S s y s t e m , 2 3 8, , w i t h o u t p l a i t e d s t r o r a g e , 2 3 3

, , , p r e - s t e e p i n g , 2 3 4

B l e a c h i n g , m a j o r b r e a k - t h r o u g h s , 1 80

B l e a c h in g p o w d e r ,

- - , a c t i o n o f a c i d , 1 6 2 , 1 6 5

- - , a n a l y s i s o f , 4 5 5

- - , c a t a l y t i c d e c o m p o s i t i o n o f , 1 6 5

- - , c h e m i c a l s t r u c t u r e , 1 61

- -, e f f e c t o f p H & t e m p . , 1 65

- -, m a n u f a c t u r e o f , 1 62

- - , r a t e o f a t t a c k o n c o t t o n , 1 6 2 , 1 6 5

B l u e i n g t i n t s , 1 8 8

B o i l e r s ,

- , s c a l i n g , 3 6 2

- , w a t e r s u p p l y , 3 6 1B r u s h i n g , 5 2

B O D , 3 7 2

B u i l d e r s ,

- , d e f i n a t i o n o f , 9 3

- , e f f e c t o n d e t e r g e n c y , 9 3

B u r r s , 1 0 7 , 4 3 3

C a d o x e n , 4 6 0 , 4 6 5 , 4 6 8

C a l c i u m h y p o c h l o r i t e , 1 2 8

- - , p r e p a r a t i o n o f , 1 6 2

- - , d e c o m p o s i t i o n o f , 1 6 2

C a r b o n f i b r e s , 4 1

C a r b o n i s a t io n o f w o o l , 3 5 5

- - -, e n z y m a t i c p r o c e s s , 1 1 3

- - - , r a p i d p r o c e s s , 1 11

C a r b o n i s i n g m a c h i n e r i e s , 1 5 0 - 1 5 2

C a s e i n f i b r e , 2 7

C a n n i z a r o i n t e rm e d i a te s , 3 4 9C a u s t i c i z a t i o n , 2 8 7

C a t a l y t i c d a m a g e , 3 5 0 , 3 5 4 , 3 5 8

C a t i o n i c s u r f a c t a n t s , 9 6

C e l l o b i o s e , 4

C e l l u l a s e t r e a t m e n t , 4 2 0

- -, e f f e c t o f t e m p e r a t u r e , 4 2 2

, , p H , 4 2 2

C e l l u l o s e ,

- , c h e m i c a l c o m p o s i t i o n , 3

- , m o l e c u l a r w e i g h t , 4

- , m o r p h o l o g y , 3

- , s t ruc tu re , 4

C e l l u l o s e I , I I , 5 , 2 4 , 2 8 5 , 2 8 6

C e l l u l o s e f i b r e s ,

- -, c o n t i n u o u s b l e a c h i n g , 2 2 4 - 2 2 9- -, c o p p e r n u m b e r , 3 5 2




- - , f lu id i ty , 458

- -, m a n - n a d e , a c e t a te , 2 5

, , c u p r a m m o n i u m ra y o n , 2 2

, , p o l y n o s i c , 2 4

C h a i n m e r c e r i z i n g m a c h i n e , 2 9 3

C h a i n l e s s m e r c e r i z i n g m a c h i n e , 2 9 4

C h e l a t i n g a g e n t s , 9 1

C h e m i c a l s t r u c t u r e o f ,

- - - , a c e t a t e f i b r e s , 2 5

- - -, a c r y l i c s , 3 4

- - - , c a r b o n f i b re s , 4 2

- - - , c h l o r o f i b r e s , 3 9

- -- , e l a s t o m e r i c f i b re s , 4 0

- - - , f l a x , 8

- - - , j u t e , 20

- -- , m o d i f i e d n y l o n , 3 3

, , p o l y e s t e r , 2 8 - 3 0- - - , n y l o n , 3 0 , 3 2

- - -, p o l y e s t e r , 2 8

- - - , p o l y p r o p y l e n e , 3 8

- - - , P T O f i b r e s , 4 2

- - - , s i lk , 14 -16

- - - , woo l , 11

C h l o r i n e d i o x i d e , 1 8 2

C h l o r i t e b l e a c h i n g , 1 8 2

- - - , c o r r o s i o n o f , 1 8 6

C h l o r o u s a c i d , 1 8 2

C l o u d p o i n t , 9 8

C o a g u l a t i o n o f im p u r i t ie s , 3 8 2

- - - , m e c h a n i s m , 3 8 3

, , b r i d g i n g , 3 8 3

, , c h a r g e p a t c h , 3 8 3C o l d b l ea c h i n g , 3 6 5 , 3 6 9

C o l d d e s i z i n g , 7 8

C o l o u r w o v e n g o o d s ,- - - , sc ou r ing o f , 90 , 94

- - - , k i e r ing o f , 133

- - - , b l e a c h i n g o f , 1 7 5

C o m b i n e d p r o c es s e s,

- -, s c o u r i n g a n d b l e a c h i n g , 1 8 0 , 1 8 5 ,

2 1 0 , 3 3 7 , 3 3 9

, , a c e ta t e f ib re s , 189

, , k n i t t e d c o t t o n , 2 1 0

, , P o l y e s t e r / c o t t o n , 1 2 6 , 2 0 6

, , s i l k , 1 8 0

- - , s c o u r i n g a n d d e s i z i n g , 7 9 , 8 4 , 3 3 6

- -, s c o u r i n g a n d m i l l i n g , 1 4 9

- -, s c o u r i n g a n d r e l a x a t i o n , 1 2 5

- -, s o l v e n t a s s i s t e d , 3 4 1

- - , e m u l s i f i e d s o l v e n t , 3 3 7 , 3 4 1- -, e n z y m e t r e a t m e n t , 3 4 2

--, desizing, scouring and bleaching, 82, 123

C o m b i n e d p r o c e s s in g e q u i p m e n t ,

- -- , B e n - b l e a c h , 3 4 0

- - - , C . R . C . p r o c e s s , 3 4 0

- -- , d e s i z i n g / s c o u r i n g / b l e a c h i n g , 3 9 9

- - - , F l e x - n i p , 3 4 0

- - -, M a r k a l p r o c e s s , 3 4 0

- -- , m e r c e r i z i n g a n d b l e a c h i n g , 3 0 5

- -- , m e r c e r i z i n g a n d d e s i z i n g , 3 0 9

- -- , R e c o - Y e t , 3 4 0

- - - , s o l a r s y s t e m , 3 4 2

Combined plasma and enzyme reatment, 423,434

C o n t a c t a n g l e , 1 0 1

C o r t e x i n w o o l , 1 0C o t t o n f a b r i c ,




- - , b l e a c h i n g o f , 8 5 - 1 2 0

- -, b o i l i n g - o f f , 8 9

- -, c o l o u r i n g m a t t e r , 1 6 6

- - , d e s i z i n g o f , 6 9

- - , s c o u r i n g , 8 6

- - , s i n g e i n g , 5 5 - 6 5

- -, m e r c e r i z i n g , 2 8 5

- - , - , a m m o n i a , 3 9

- - , - , h o t , 3 0 6

C r a b b i n g o f w o o l , 1 1 0 ,1 5 2

C r i t i c a l m i c e l l e c o n c e n t r a t i o n , 9 4 , 1 0 3

C o r p p i n g , 5 2

C r o s s - s e c t i o n o f ,

- - - , a c ry l i c s , 35

- - - , c o t ton , 4

- - - , f l a x , 1 7

- - - , h e m p , 1 9- - - , j u t e , 19

- - - , m o d a c r y l i c , 3 6

- - - , n y l o n , 3 1 , 3 4

- -- , p l a s m a t r e a t e d w o o l , 4 0 9

- - - , p o l y e s t e r , 2 9

- - - , p o l y p r o p y l e n e , 3 8

- - - , r e m i e , 1 8

C r o s s - l i n k s i n w o o l , 1 11

C r y s t a l l i n i t y o f ,

- -, c o t t o n ,

- - , p o l y e s t e r , 2 8

-- , s i lk , 15

- - , woo l , 13

D e c a t i s i n g a p p a r a t u s 1 5 2 - 1 5 5D e c h l o r i n a t i n g a g e n t , 2 0 4

D e c o m p o s i t i o n o f H 2 02 , 77

D e c o n v o l u t i o n c o u n t , 4 6 4

D e g r a d a t i o n o f c e l lu l o s e , 3 4 4 - 3 5 5

- - - , d u r i n g b l e a c h i n g , 1 6 3 , 1 6 6 , 3 5 0

, , d e s i z i n g , 3 4 4

, , s c o u r i n g , 3 4 6 - 3 4 9

- -- , i n h y p o c h l o r i t e , 3 5 0 - 3 5 3

, , hydrogen peroxide, 1 70, 173, 182, 353

, , a lka l i , 346

D e g r a d a t i o n o f ,

- - , f l a x , 203

- - , j u t e , 197

-- , s i lk , 179, 194, 356

D e g r a d a t i o n o f n y l o n ,

- - - , d u r i n g b l e a c h i n g , 1 8 5

, , c h l o r i t e b l e a c h i n g , 1 8 8

D e g r a d a t i o n o f p o l y e s t e r , 3 5 7- - - , on e xposu re to ~ , - r a ys , 413

D e a g r a d a t i o n o f w o o l , 3 5 4 - 3 5 6

- - -, in a c i d s a n d a l k a l i e s , 3 5 5

, , b l e a c h i n g , 3 5 5

, , c a r b o n i s i n g , 3 5 5

, , d e c a t i s i n g , 3 5 5

D e g r e a s i n g o f w o o l b y p l a s m a , 4 0 7

D e g r e e o f p o l y m e r i s a t i o n ,

- - - , f l a x , 1 7

--- , s i lk , 15

- -- , p o l y p r o p y l e n e , 3 7

D e g u m m i n g o f,

- - , r e m i e 1 1 8

- - , s i lk , 114 -116

- -, s i lk b y p l a s m a , 4 0 7D e g u m m i n g 3 5 1 , 3 9 9 , 4 0 9




- , a n d p H , 1 1 6

- , w i t h a l k a l i a n d a c i d , 1 1 6

- , - , e n z y me s , 1 1 7

- , - , foam, 117

- , - , soap , 116

- , - , s y n t h e t i c d e t e r g e n t , 1 1 6

- , pa r t i a l , 117

- , w e i g h t l o s s , 1 1 5

D e l i g n i f i c a t i o n o f f la x , 20 3

D e l u s t e r i n g o f a c e ta t e f i b re s , 1 23

D e m i n e r a l i s a t i o n o f c o tt o n , 8 8

D e s i z i n g , 6 9 - 8 4

- , a f t e r - w a s h , 1 0 0

- , B O D , 3 7 7

- , m i x t u r e , 9 9

- , o f b l e n d e d f a b r i c s, 7 8

- , - , c o t t o n , 6 9- , - , s y n t h e t i c f a b r i c s , 7 7

D e s i z i n g o f s ta r c h ,

- - - , a c i d a p p l i c a t i o n , 7 3

- - - , e n z y m e a t t a c k , 7 2 - 7 5

- - - , o x i d a t i o n m e t h o d , 7 5 - 7 7

- -- , p e r o x y c o m p o u n d s , 3 3 7

D e s i z i n g m a c h i n e r i e s, 7 9 - 8 4

- -, b a t c h p r o c e s s , 7 9

- -, p a d - b a t c h , 8 0

- - , pad- ro l l , 81

- - , p a d - s t e a m , 3 3 7

- -, p a d - s t o r e , 3 3 8

- - , c o n t i n u o u s , 8 1

- - , - , J -Box , 83

- - , - , r o p e f o r m , 8 0- - , - , s o l v e n t , 8 3

D e s u i n t i n g , 2 3 0

D e t e r g e n c y , 4 4 , 1 0 1 , 1 0 3

- , d e t a c h m e n t o f o il s , 1 0 1

- , e f f e c t o f C M C , 3 4 4

- , e f f e c t o f e n z y m e , 4 3 1

- , t h e o r y o f s o i l r e mo v a l , 1 0 2

D e t e r g e n t s ,

- , a n i o n i c g r o u p , 1 1 8

- , in te r fac ia l t ens ion , 101

- , c loud po in t , 88

- , c o n c e n t r a t i o n , 9 4

- , n o n - i o n i c s t r u c t u r e , 9 7

- , so i l ing a c t iv i ty , 101

- , so i l susp en din g , 101 , 102

D i m e n s i o n a l s t ab i l it y , 2 7 0

D i s a d v a n t a g e s o f ,

- -, b l e a c h i n g w i t h p e r o x i d e , 1 81, , b l e a c h i n g p o w d e r , 1 67

- - , - - , s o d i u m c h l o r i t e , 1 8 7

, , s u l p h u r d i o x i d e , 19 3

- - , -, o f ju te , 199

D r a v e s t e s t, 4 5 2

D o l l y m a c h i n e , 1 4 9

D o u b l e b l e a c h o f s il k , 1 95

D y n e l , 3 9

Ecru s i lk , 115

E c o l o g y , 3 7 2

E c o n o m y t h r o ug h ,

- -, p r o c e s s m o d i f i c a t i o n , 3 6 8

- - , - , s e q u e n c e , 3 6 9

E f f l u e n t p r o b l e m s i n ,- - - , aux l i l i a r i e s , 378



S u b j e c t I n d e x 481

- - - , b l e a c h in g , 3 7 8

- - -, d e s i z in g , 3 7 6

- - - , s c o u r in g , 3 7 7

E f f l u e n t t r e a t m e n t ,

- -, a n d b i o t e c h n o l o g y , 4 3 5

E l a s t i c r e c o v e r y o f S p a n d e x , 4 1

E l e c t r o l y t e e f f e c t d u r in g ,

- - - , des iz ing , 95

- -- , m e r c e r i z i n g , 2 9 2

- - - , o p t i c a l b r ig h t e n in g , 3 2 5

E l e c t r o l y t i c m e t h o d ,

- -, h y p o c h lo r i t e , 1 63

- - , pe r ox i de , 169

E m u l s i f i c a t i o n o f o i l, 8 7, 8 8

E m u l s i f i e d s o v e n t s , 1 0 5

E m u l s i o n s c o u r i n g , 3 3 7

- - , m e c h a n i s m o f , 1 0 6- - , r ec ip e , 106

E n z y m e s ,

- , t e x t i l e a p p l i c a t i o n , 4 1 8

- , c h e m is t r y o f , 4 1 8

-, m e c h a n i s m o n te x t i le , 4 1 8

- , h e a t p r o t e c t i o n , 1 4

- , p H r e s p o n s e , 7 4

- , sa l t add i t ion , 75

- , tox ins , 422

E n z y m a t i c d e g r a d a t i o n d u r in g ,

- - -, b l e a c h in g o f j u t e , 2 0 1

- - -, d e s i z in g , 3 4 5

- - - , b io - p o l i s h in g , 4 2 8

E n z y m a t i c p r o c e s s in g ,

- -, a d v a n t a g e s o f , 4 2 4- - , d i s a d v a n ta g e s o f , 4 2 5

- - , o f co t ton , 425

- - , - , s i l k , 4 2 8

- - , - , w o o l , 4 3 2

E n z y m a t i c ,

- , b l e a c h in g o f c o t t o n , 4 2 8

- , - - , w o o l , 4 3 2

-, c a r b o n i s a t i o n o f w o o l , 4 3 3

- , d e g u m m i n g o f s il k , 4 2 6

- , d e s i z in g o f c o t t o n , 4 2 6

-, h a n d m o d i f i c a t i o n o f w o o l , 4 3 5

- , m e r c e r i z a t i o n , 4 2 6

-, s h r in k p r o o f i n g o f w o o l , 4 3 5

- , s c o u r in g o f c o t t o n , 4 2 6 , 4 2 7

E n z y m e e f fe c t o n,

- - - , dyes , 429

- - - , m e c h a n ic a l a g i t a t i o n , 4 3 1

- - - , r es in s , 430- - - , su r f ac tan ts , 430

- - - , w a s h in g p r o c e s s , 4 3 1

E p ic u t i c l e , 1 0

E u m e l a n i n , 1 7 3

E v a l u a t i o n o f ,

- -, l u b r i c a n t s , 4 4 6

- - , s a p o n i f i c a t i o n v a lu e , 4 4 7

- -, u n s a p o n i f i e d m a t t e r , 4 4 7

- -, w h i t e n i n g e f f i c i e n c y , 4 6 8

- - , w a x c o n t e n t i n c o t t o n , 4 4 5

F a b r i c s ,

- , b l e n d m e r c e r i z a t i o n o f , 2 9 1

- , k n i t t e d m e r c e r i z a t i o n o f , 3 0 3

- , l i q u i d a m m o n i a t r e a t m e n t o f , 3 09Fat ty ac ids , 131




- - , i n c o t t o n w a x , 7 , 4 4 0

-- , in w oo l , 14 , 107

F a t t y a l c o h o l s i n c o t t o n w a x , 7

Fib r i l , 4

F i b r i o n , 1 4

Fib re ,

- , ace ta te , 25

- , co t ton , 3

- , f l a x , 1 7

- , h e m p , 1 9

- , ju te , 19

- , r a y o n , 2 2

- , r em ie , 18

- , r e g e n e r a t e d p r o t e in s , 2 6

- , s y n th e t i c , 2 7 - 5 4

- , v i scose , 28

- , woo l , 8F ib r e c l a s s i f i c a t i o n , 2

F ib r e s t r u c tu r e ,

- - , case in , 27

- - , co t ton , 2

- - , l inen , 4

- - , p ro te in f ib res , 26

- - , r ayon , 22 , 23

-- , silk, 14, 15

- -, s y n th e t i c f i b r e s, 2 2 - 2 4

F i b r o l a n e , 2 6

F la x ,

- , b l e a c h i n g o f , 2 0 1 , 2 0 2

- , r e m o v a l o f r u s t , 2 0 2

F l a v o n e p i g m e n t , 1 8 0

F l e i s s n e r s c o u r i n g b o w l , 1 4 6F l e x - n i p , 3 4 0

F lu e g a s , 3 8 2

F lu id i t y o f c o t t o n , 3 5 0 , 4 5 8F l u o r e s c e n t b r i g h t e n i n g a g e n t s ( F B A ) ,

- -- , a b s o r p t i o n a n d e m is s io n c u r v e s , 3 2 0

- -- , m e c h a n i s m o f, 3 2 3

- -- , p h o t o - y e l l o w i n g a n d t e n d e r i n g , 3 2 7

- -- , q u a n i t i ta t i v e m e a s u r e m e n t s o f, 4 6 8

- - - , s a l t sens i t iv i ty , 325

- - -, s o lu b i l i t y i n b l e a c h l i q u o r , 3 2 6

- -- , t e m p e r a t u r e a n d e x h a u s t i o n , 3 2 4

- - -, w e t f a s m e s s , 3 2 7

F B A , a p p l i c a t i o n t o ,

- , - - , a c r y l i c s , 3 3 0

- , - - , b l e n d e d f a b r i c s , 3 2 2

- , - - , c e l l u lo s i c f i b r e s , 3 2 6

- , - - , C D P E T f i b r e s , 3 3 1

- , - - , n y l o n , 3 2 9- , - - , p o l y e s t e r 3 2 8

- , - - , p o l y v i n y l c h l o r i d e , 3 3 2

- , - - , s i lk , 328

- , - - , w o o l , 3 2 7

G a s s in g e in g o f ,

- - - , b lended f ab r ics , 57

- - - , co t ton , 56

- - - , po lyes te r , 57

- -- , r e g e n e r a t e d f i b re s , 5 6

- - - , woo l , 56

G a s s i n g e i n g m a c h i n e s , 5 8 - 6 3

G a la c tu r o n i c a c id , 8

G e b a u e r k i e r , 1 3 5

G e n e r i c n a m e s o f fi b re s , 3Glass f ib res , 43




G l a s s - t r a n s i t io n t e m p e r a t u r e o f,

. . . . , a c r y l i c s , 3 6

. . . . , o l e f i n f i b r e s , 3 7

. . . . , p o l y e s t e r , 2 9

. . . . , S p a n d e x , 4 1

. . . . , e f f e c t o n s i n g e i n g , 5 7

G l u c o s e , 4 , 4 4 9

G l u c o n a t e s , 1 7 2

G l u t a m i c a c i d , 1 2

G o l d t h w a i t t e st , 4 6 6

G l y c e r i n e s , 1 2 , 8 7

H a r d w a t e r , 44 1

- - , e f f e c t o n c o t t o n , 3 5 3

, , s i l k , 1 9 9

H a r s h h a n d l e o f ,

- - - , s i l k , 179 , 199- -- , p l a s m a t r e a t e d w o o l , 4 1 0

H a r r i s o n t e s t , 4 6 2

H e a t - s e t t i n g , 2 5 9 - 2 7 7

- - , i n a u t o c l a v e , 2 6 1

- -, b o n d r u p t u r e , 2 6 0

- -, c h a n g e s i n d y e a b i l i t y , 2 7 1

, , s t r u c t u r e , 2 7 2

- - , b y c o n t a c t m e t h o d , 2 6 1

- -, b y c o n v e c t i o n ( t e n te r ) , 2 6 3

- - , b y i n f r a - r e d , 2 6 6

- -, o f k n i t t e d f a b r i c s , 2 6 5

-- , o f p o l y e s t e r , 2 5 9

- - , s t a g e s , 2 3 0

- -, o f t e x t u r i s e d f a b r i c s, 2 5 6

H e a t - s e t t i n g o f b l e n d e d f a b ri c s,. . . . . , p o l y e s t e r / c o t t o n , 2 7 1

. . . . . , p o l y e s t e r / l i n e n , 2 7 2

. . . . . , p o l y e s t e r / s i l k , 2 7 2

. . . . . , p o l y e s t e r / w o o l , 2 7 1

. . . . . , p o l y v i n y l c h l o r i d e /c e l l u l o s e , 2 7 2

H e a t - s e t ti n g d e g r e e, d e t e r m i n a t i o n b y ,

, , a s s e s s m e n t o f h a n d l e ,

, , c r e a s e r e c o v e r y , 4 6 9

, , i o d i n e a b s o r p t i o n , 4 7 0

, , s h r i n k a g e t e s t , 4 6 9

H e m i - c e l lu l o s e , i n

- , - , c o t t o n , 8

- , - , f l a x , 1 7

- , - , h e m p , 1 9

- , - , j u t e , 20 , 2 1 , 199

- , - , l i nen , 201

H e x a - m e t h y l e n e d i a m i n e , 3 0

H i g h e n e r g y r a d i a t io n ,- -- , b l e a c h i n g o f t e x ti l e s, 4 1 3

- - - , d e g r a d a t i o n a n d c r o s s - l i n k i n g , 4 1 2

H i g h p r e s s u r e k i e r , 1 3 3

H i g h w e t m o d u l u s v i s co s e , 2 3

H i s t i d i n e , 1 2

H y d r o c e l l u l o s e , 1 8 2, 3 4 5

- , s t a i n i n g t e s t , 4 6 1

H y d r o s u l p h i t e ,

-, i n b l e a c h i n g , 1 9 3

- , s t a b i l i s e d , 1 9 5

- , a n a l y s i s o f , 4 5 7

H L B s y s t e m , 9 5

H y d r o g e n p e r o x i d e ,

- - , a c t i v a t i o n o f , 1 7 0

- - , a n a l y s i s o f , 4 5 6- -, b l e a c h i n g a c t i o n , 1 6 9




- -, c a t a l y t ic a c c e l e r a t i o n , 3 5 4

- - , d e c o m p o s i t i o n o f , 1 6 9 , 3 5 5 , 3 5 6- -, e x p r e s s i o n o f s tr e n g t h , 1 69

- -, m a n u f a c t u r e o f , 1 6 6 , 1 7 2

- -, r e a c t i o n w i t h c e l l u lo s e , 3 5 0

- -, s t a b i l i s e r s , 1 7 0 - 1 7 3

- - , r e a c t i o n w i t h w o o l , 3 5 5

H y d r o g e n p e r o x i d e b l e a c h i n g o f,

. . . . , a c e t a t e , 1 8 0

. . . . , a c r y l i c s , 1 8 0

. . . . , c o t t o n , 1 7 2

. . . . , j u t e , 9 7

. . . . , s i l k , 1 7 8

. . . . , v i s c o s e , 1 8 0

. . . . , w o o l , 1 7 3 - 1 7 8

H y d r o g e n p e r o x i d e , e f f e c t o f,

, , c o n c e n t r a t i o n , 1 7 3, , f l u id i t y , 1 7 0

- - , - - , i m p u r i t i e s , 1 6 9

, , m e t a l i o ns , 3 5 3 , 3 5 4

- - , - - , p H , 1 7 2

, , s o d i u m s i l ic a t e , 3 5 3

- -, - -, t e m p e r a t u r e , 1 7 2

, , t i m e , 1 73

, , w a t e r , 1 71

H y p e r f i l t r a t i o n , 3 8 8

( s ee r e v e r s e o s m o s i s )

H y p o c h l o r i t e b l e a c h i n g , 1 6 2 - 16 8

H o t m e r c e r i z a t i o n ,

- - , a d v a n t a g e s o f , 3 0 8

- -, c h a n g e s i n p r o p e r t i e s , 3 0 7

- - , c o m p a r i s o n , 3 0 7- - , m e t h o d s , 3 0 7

H u s k i n c o t t o n , 8 8

I d e n t i f i c a t i o n o f s ta r c h , 4 5 0

I m m a t u r e c o t t o n, 2 1 0

I m p u r i t i e s i n ,

- - , c o t t o n , 5 , 8 6

- - , j u t e , 1 2 0

- - , s i lk , 1 1 5

- - , w a t e r , 3 6 1

- - , w o o l , 1 3 , 1 0 7

I m p r e g n a t i o n ,

-, B e n - i m p a c t a , 2 3 0

I n o r g a n i c s a l ts i n ,

- - - , co t to n , 7 , 8 7

- - - , j u t e , 2 0

- - - , s y n t h e t i c f i b r e s , 1 2 0

- - - , w o o l , 1 2 6I n s p e c t i o n o f f a b r ic ,

- - - , b u r l i n g , 5 0

- - - , b y l a s e r b e a m s , 5 0

- -- , m e n d i n g , 5 0

- - - , p e r c h i n g , 4 9

I n t e r l o c k s t it c h , 5 1

I o n - e x c h a n g e r e s i n , 3 6 4

J a c k s o n k i e r , 1 3 6

J a f f e r s o n W a l k e r K i e r , 1 3 4

J - B o x ,

- - , B e c c o , 1 3 9 , 2 2 9

- - , b l e a c h i n g r a n g e , 2 2 4 - 2 2 6

- - , d e s i z i n g , 8 3

- -, D u B e c s y s t e m , 2 2 8- - , D u P o n t , 1 3 9 , 2 2 9




- - , F M C w e t b o t t o m , 2 2 7

- -, m a t e r i a l o f c o n s t r u c t i o n , 2 2 4- -, p r e p a r a t i o n r a n g e , 1 2 6

J e t w a s h e r , 2 5 0

Jig ,

- , p r o c e s s , 7 9

- , s c o u r i n g , 1 3 7

J - p i l e r , 2 2 4

Ju te ,

- , b l e a c h i n g o f , 1 9 6 - 1 9 8

- , c h e m i c a l c o n s t i t u t i o n o f , 2 1

- , c o t t o n i s a t i o n o f , 2 0 1

- , d i m e n s i o n s o f , 2 0

- , d r a w b a c k o f , 1 2 9

- , l i gn in c on te n t , 19 , 21

- , p r o p e r t i e s o f , 2 1

K B v a l u e , 1 0 6

K e n a f , 2

K e r a t i n , 1 1

K i n d s o f f i b re s , 1 - 4 7

Kie r ,

- , c i r c u l a t i o n , 3 3

- , h i g h p r e s s u r e , 1 3 3

- , h o r i z o n t a l , 1 3 5

- , J a c k s o n , 1 3 8

- , l o w p r e s s u r e , 1 3 2

- , o p e n - w i d t h , 1 3 6

- , ve r t i c a l , 133

- , W a l s h ' s , 1 3 3

K i e r b o i l i n g ,

- - , a s s i s t a n t s , 1 3 4- - , c o l o u r e d g o o d s , 9 0

- - , e f fe c t o f a i r , 348

- -, p r o c e d u r e , 1 3 4- -, y a r n i n h a n k , 1 0 9

K i t t i e s , 4 4 7

K n i t t e d f a b r i cs ,

- - , b l e a c h i n g e q u i p m e n t , 2 2 0 , 2 2 7 , 2 3 7

- - , h e a t - s e t t i n g o f , 2 6 5

- -, m e r c e r i z a t i o n o f , 3 0 4

- - , o p e n i n g o f , 2 2 4

- - , s c o u r i n g o f , 1 0 4

- - , s inge ing o f , 163

- - , s o l v e n t s c o u r i n g , 1 0 6

- - , t r e a t m e n t w i t h l i q u i d a m m o n i a , 3 1 1

- -, w a x c o n t e n t , 4 4 6

L a n o l i n , 1 8

L a m i n a t e d s t r u c t u r e o f s i lk , 1 5L i g n i n i n ,

- - , co i r , 21

-- , f lax , 21

-- , ju t e , 19 , 21 , 199

- - , - , a c t i o n o n b l e a c h i n g , 1 9 7

- - , - , r e m o v a l o f , 2 0 1

L i m e - s o d a s c o u i n g , 8 9

L i n e n ,

- , b l e a c h i n g o f , 2 0 1

- , - , l o s s i n w e i g h t , 1 4 , 2 0 1

- , r e a c t i o n w i t h c h l o r i te , 2 0 2

- , - - , h y d r o g e n p e r o x i d e , 2 0 2

, , p e r a c e t i c a c id , 2 0 2

- , s c o u r i n g o f , 1 1 9

L i p a s e s , 4 1 8L i q u id a m m o n i a ,




- -, c o m p a r i s o n , 3 1 2

- - , e f f e c t o f , 3 1 1

- - , P r o g r a d e p r o c e s s , 3 1 0

- -, p r o p e r t i e s o f t r e a t e d g o o d s , 3 1 3 - 3 1 5

- - , S a n f o r - s e t p r o c e s s , 3 0 9

- -, t r e a t e d , t e s t , 4 6 6

L i t h i u m h y p o c h l o r i t e , 1 63

L o - f l o p r o c e s s , 1 4 2

L o n g v e g e t a b l e f i b r e s, 1 8

- - - , a s p e c t r a t i o , 2 0

L o o s e w o o l s c o u r i n g , 1 07

L o t n u m b e r , 5 2

L o w e n e r g y p r o c e s s e s , 3 1 6 , 31 7

L u b r i c a n t s , 6 9 , 1 0 3 , 1 0 4 , 4 4 6

- , f o r w o o l y a r n , 1 0 9

- , f o r w o r s t e d , 1 1 0

- , r e m o v a l o f 1 1 0

M a g n e s i u m s u l p h a te i n b l e a c h i n g , 1 71

M a l t a m y l a s e s , 7 3

M a l t e n z y m e , 4 4 9

M a l t o s e , 7 8 , 8 9

M a n - m a d e f ib re s ,

- - - , a c r y l i c s , 3 4

- -- , m i s c e l l a n e o u s , 3 8

- - - , n y l o n , 2 9

- - - , o l e f i n f i b r e s , 3 7

- - - , p o l y e s t e r , 2 7

- -- , r e g e n e r a t e d f i b re s , 2 2

M a n u f a c t u r i n g p r o c e s s ,

- -, a c e t a t e s , 2 5

- -, a c r y l i c s , 3 5- - , n y l o n , 3 1

- -, p o l y e s t e r , 2 8

- -, r a y o n , 2 3M a r k a l p r o c e s s , 1 4 4

M a t u r i t y o f c o tt o n , 4 6 6

M e c h a n i s m o f b l e a c h in g w i th ,

. . . . , c h l o r i t e , 1 8 2

. . . . , h y p o c h l o r i t e , 1 6 2 , 1 6 3

. . . . , l i t h i u m h y p o c h l o r i t e 1 43

. . . . , p e r a c e t i c a c i d , 1 8 9 , 1 9 0

. . . . , p e r o x i d e , 1 7 0

. . . . , p e r o x y g e n c o m p o u n d s 1 96

. . . . , r e d u c t i v e a g e n t s , 1 7 6

. . . . , T A E D / H 2 0 2 , 1 90

M e c h a n i s m o f r e a c ti o n w i t h ,

. . . . , a l k a l i , 3 4 8

. . . . , e n z y m e , 4 2 0

. . . . , i n w o o l s c o u r i n g , 1 0 8

. . . . , e m u l s i o n s c o u r i n g , 1 0 6

M e c h a n i c a l c l e a n in g p r o c e s s ,

- -- , b r u s h i n g , 5 2

- - - , c r o p p i n g , 5 2

- - - , s h e a r i n g , 5 4

M e c h a n i c a l r e m o v a l o f w a t e r , 3 45

M e d u l l a i n w o o l , 11

M e l a n i n e , 1 7 3

M e n d i n g , 5 0

M e r c e r i z a t i o n o f,

- , b l e n d e d f a b ri c s ~ 2 9 1

- , c o t t o n , 2 7 9 - 3 1 5

- , f l a x , 2 9 0

- , k n i t g o o d s , 3 0 3

M e r c e r i z a t i o n o f c o tt o n ,- -- , a d s o r p t i o n o f b a r i u m h y d r o x i d e , 4 6 0




, , c a u s t i c s o d a , 2 8 3

, , d y e s , 2 8 9

, , w a t e r , 2 8 8

- -- , c h a n g e s i n p r o p e r t i e s , 2 8 0 - 2 9 0

- -- , i n h a n k f o r m , 3 0 2

M e r c e r i z a t i o n , e f f e c t o f ,

- , - - , a l k a l i e s , 2 8 1 , 2 8 2

- , - - , f a b r i c c o n s t r u c t i o n , 2 8 8

- , - - , i m m a t u r e c o t t o n , 2 9 0

- , - - , l u s t r e , 2 8 6

- , - -, s tr u c t u r a l m o d i f i c a t i o n , 2 8 5

- , - - , s h r i n k a g e , 2 8 5 , 2 8 6

- , - - , s w e l l i n g , 2 8 1

- , - - , t e m p e r a t u r e , 2 8 2

- , - -, t e n s i o n , 2 8 7

- , - - , w a t e r d u r i n g w a s h i n g , 2 8 4

- , - - , w e t t i n g a g e n t s , 2 8 0M e r c e r i z a t i o n ,

-, h a l f m e r c e r i z a t i o n , 2 8 9

- , h o t , 3 0 6

- , l i q u i d a m m o n i a , 3 0 9

- , r e c o v e r y o f c a u s t i c s o d a , 3 8 7

- , s t r e n g t h , 2 8 8

- , t h e o r y , 2 8 3

M e r c e r i z i n g e f f i c ie n c y , t e s t b y ,

, , b a r i u m a c t i v i t y n u m b e r , 4 6 6

, , b e n z o p u r p u r i n e , 46 5

, , d e c o n v o l u t i o n c o u n t , 4 6 4

, , G o l d t h w a i t m e t h o d , 4 6 6

- - , - - , i n f r a - r e d a n a l y s i s , 4 6 8

, , l u s t r e , 4 6 7

, , s t a i n i n g , 4 6 6, , s p o t t i n g , 4 6 5

, , s w e l l i n g i n d e x , 4 6 5

, , X - r a y a n a l y s i s , 4 6 7

M e r c e r iz i n g m a c h i n e s

- - , c a u s t i c i z i n g , 2 9 8

- -, c h a i n le s s , 2 9 5 , 2 9 7

- - , c l i p - c h a i n , 2 9 3

- - , c l o t h ( w o v e n ) , 2 9 3

- -, c o m b i n e d , 3 0 5

- - , c o r e , 3 0 0

- -, D i m e n s a , 3 0 1

- - , d u a l p u r p o s e , 3 0 1

- -, E c o m e r c e , 2 9 6 , 2 9 9

- - , F l e x - n i p , 3 0 0

- - , G o l l e r p e r f e c t a , 3 0 1

- - , h o t , 3 0 1

- - , k n i t g o o d s , 3 0 4

- -, l i q u i d a m m o n i a , 3 1 1

- -, m i n i m e r c e , 2 9 3

- -, P r o g r a d e , 3 1 0

- -, r e c u p e r a t o r , 2 9 7

- - , S a n f o r s e t r a n g e , 2 1 1

- - , y a m , 3 0 2

M e t h o d s t o g e n e r a t e p l a s m a , 3 9 8

M e t h y l e n e b lu e a b s o r p t i o n , 3 5 2

M i c e l l i s a t i o n o f s u r f a c t a n t s , 1 0 0

M o d a c r y l i c f i b r e , 3 4 , 3 6

M o d i f i e d f i b r e s ,

- - , a c r y l i c , 3 6

- -, n y l o n , 3 3

- -, p o l y e s t e r , 3 0

M o i s t u r e s o r p t i o n ,

- - , d e t e r m i n a t i o n o f , 4 4 7- -, o f a c e t a t e s , 2 6




- - , - , a c r y l i c s , 3 5

- - , - , c o t t o n , 2 8 8

, , f l a x , 2 1

- - , - , j u t e , 2 1

- - , - , n y l o n , 3 2

, , P B I f i b r e s , 3 4

, , p o l y e s t e r , 2 9

, , p o l y p r o p y l e n e , 3 8

, , v i s c o s e , 2 3

M o l e c u l a r s t r u c t u r e o f ,

- - - , a c r y l i c s , 3 4

- - - , c o t t o n , 4

- -- , p o l y e t h y l e n e , 3 7

- -- , p o l y p r o p y l e n e , 3 7 , 3 8

- -- , p o l y v i n y l a l c o h o l , 4 0

M o t e s , 5 , 1 4 , 8 6-, r e m o v a l o f , 4 5 3

M u l t i - l a y e r s t e n t e r , 2 6 1

N a t u r a l f i b r e s , i m p u r i t i e s o f ,

, , c e l l u l o s e a n d n o n - c e l l u l o s i c , 6

, , c o t t o n , 5

, , c o t t o n w a x , 7

, , f l a x , 2 1

, , s i lk , 21

, , w o o l , 13

N a t u r a l y e l l o w i s h t i n t i n,

. . . . , c o t t o n , 1 6

- - - -, j u t e , 1 9 6

. . . . , l i n e n , 2 0 2

. . . . , s i l k , 1 7 8

. . . . , w e f t k n i t t e d c o t to n , 2 1 0

. . . . , w o o l , 1 7 3

N y l o n , 2 9 - 3 4-, m a n u f a c t u r i n g o f , 3 1

-, m o d i f i e d , 3 3

- , p r o p e r t i e s o f , 3 2

N y l o n , b l e a c h i n g w i t h ,

, , p e r a c e t i c a c i d , 19 0

- , - - , p e r o x y g e n c o m p o u n d s , 1 96

, , r e d u c t i v e a g e n t s , 1 95

- , - - , s o d i u m c h l o r i t e , 1 8 4

N y l o n , s c o u r i n g o f , 1 2 1

- , h e a t - s e t t i n g o f , 2 6 7

O l e f i n f i b r e s , 3 7

O p e n e r ( f a b r i c ) , 2 4 4

O p e n - w i d t h b l e a c h i n g e q u i p m e n t ,

. . . . , b l e a c h i n g , 2 8 1

. . . . , d e s i z i n g , 8 0

. . . . , s c o u r i n g , 1 3 8

. . . . , w a s h i n g , 2 4 7 - 2 5 5

O p t i c a l b r i g h t e n i n g a g e n t s ,

- - - , c h e m i c a l c o n s t i t u t i o n o f , 3 2 2

- - - , c o n s u m p t i o n o f , 3 2 1

- - - , m e c h a n i s m o f , 3 2 5

- - - , a p p l i c a t i o n o f , 3 2 5 - 3 3 7

O r l o n , 4 2 , 1 8 1

O x o n , 1 9 6

O x i d a t i o n o f c e l l u lo s e , 3 5 2 , 3 5 8

- -- , w i t h b r o m i t e , 3 4 5

O x i d a t i v e d a m a g e o f c e l l u lo s e , 3 4 8 , 3 5 4

- - - , w o o l , 3 5 5

O x y c e l l u l o s e , 8 9, 9 0 , 3 4 6 , 3 5 0-, d e t e r m i n a t i o n o f , 4 5 5




P a d - s t e a m p r o c e s s , 3 3 7

P a d - s t o r e p r o c e s s , 3 3 8

P a r a f f i n w a x , 8 8

P e c t i c s u b s t a n c e s , 5 , 6 , 8 8

P e r a c e t i c a c i d ,

- - , a c t i v a t o r s f o r , 1 8 9

- -, b l e a c h i n g o f a c e t a t e , 1 91

, , ac r y l i c s , 191

, , j u t e , 1 9 8

, , n y l o n , 1 9 0

- -, - -, p o l y e s t e r / c o t t o n , 2 0 5

- -, m a n u f a c t u r e o f , 1 8 8

- -, m e r i t s a n d d e m e r i t s o f , 1 9 1

- - , p r o p e r t i e s o f , 1 8 9

- - , s t ab i l i ty o f , 189

- -, i n h o u s h o l d d e t e r g e n t s , 1 8 9

P e r b o r a t e s , 1 8 9P e r c h i n g , 4 9

P e r f u m e d f ib r e s, 4 3

P e r h y d r o x y l i o n s, 1 79

P e r m a n e n t h a r d n e s s , 3 6 3

P e r m o n o s u l p h u r i c a c i d , 1 7 8

P e r m o n o s u l p h o n a t e , 1 9 6

P e r o x i d e ,

- , a d v a n t a g e a n d d i s a d v a n t a g e s , 1 8 1

- , b l e a c h i n g o f c o t to n , 1 7 0

- , - - , b l e n d e d f a b r ic s , 2 0 6

- , - - , s i lk , 178

, , s y n t h e t i c f i b r e s , 1 8 0

- , - - , w o o l , 1 7 4

- , v o l u m e d e f i n e d , 1 6 9

P h o t o - b l e a c h i n g o f w o o l , 1 94

P h o t o - y e l l o w i n g o f ,

- - , ac ry l i c s , 18

- - , ju te , 199

- - , o p t i c a l b r i g h t e n e r s , 3 2 5

-- , s i lk , 328

- - , w o o l , 1 7 4 , 3 2 7

P i l e r , 2 4 4

P K S u n i t , 2 3 8

P l a s m a ,

- , c o n c e p t t o , 3 9 5

- , co ld , 396

- , c o r o n a d i s c h a r g e , 3 9 6

- , g e n e r a t i o n , 3 9 7

- , g l o w - d i s c h a r g e , 3 9 6

- , i n t e r a c t i o n w i t h s u b s t r a t e , 4 0 4

- , r e a c t i o n , 4 0 5

- , - , i n i ti a t io n f o r g r a f ti n g , 4 0 6

- , - , o x i d a t i o n , 4 0 6

- , - , p e r o x i d e f o r m a t i o n , 4 0 6

- , - , r e c o m b i n a t i o n , 4 0 5

P l a s m a g e n e r a t i n g e q u i p m e n t ,

- - - , b a t c h , 4 0 3

- - -, c o n t i n u o u s , 4 0 4

- - - , c o r o n a r e a c t o r , 4 0 1

- - - , l a b o r a t o r y , 3 9 9

- - - , l o w p r e s s u r e , 4 0 1

- - - , o n e a t m o s p h e r e , 4 0 2

P l a s m a t r e a t m e n t f o r ,

- - -, b l e a c h i n g , 4 1 0

- - - , d e s i z i n g , 4 1 0 , 4 1 1

- -- , i m p r o v e d d y e a b s o r p t io n , 4 0 7 - 4 0 9

- - -, m e r c e r i z a t i o n , 4 1 0P h o t o - s t a b i l i ty o f b l e a c h e d j u t e , 1 9 9 , 2 0 0 - - -, s o il r e p e l l e n c y , 4 1 1




- - - , s u r f a c e m o d i f i c a t i o n , 4 0 7

- - -, w e t t a b i l i t y a n d w e t t i n g , 4 1 O, 4 1 1P r e v e n t i o n o f c o rr o s io n ,

- - -, in c h l o r i t e b l e a c h i n g , 4 8 6

P r o g r a d e p r o c e s s , 3 0 9

P r o p e r t i e s o f fi b r e s ,

- - - , a c e t a t e , 2 6

- - - , a c r y l i c s , 3 5

- - -, c o t t o n , 2 4

- - - , f l ax , 21

- - - , j u t e , 21

- -- , m o d a c r y l i c s , 3 6

- -- , n y l o n , 3 2

- -- , p o l y e s t e r , 2 9

- - -, v i s c o s e , 2 4

P r o t e i n i n c o t t o n , 5 , 6 , 8 8

P o l y a c r y l a t e o f s u g a r, 1 7 2P o l y c a r b o n a t e f i b r e , 4 3

P o l y e t h y l e n e f i b re s , 3 7

P o l y e s t e r , 2 7 - 2 9

P o l y n o s i c f i b r e s , 2 3

P o l y p r o p y l e n e f i b r e , 3 7

P o l y v i n y l c h l o r i d e , 3 9

P o l l u t i o n ,

- , a i r a n d w a t e r , 3 7 2

-, l o a d s o f c o t t o n , 3 7 4 , 3 7 5

- , - - , s y n t h e t i c f i b r e s , 3 7 3

- , - - , w o o l , 3 7 8

-, a s s e s s m e n t o f p a r a m e t e r s , 3 7 2

- , p r o b l e m s i n t e x t i le s , 3 7 1

- , t o l e r a n c e l i m i t , 3 7 3

- , e f f l u e n t s f r o m b l e a c h i n g , 3 7 8, , d e s i z i n g , 3 7 6

- , - - , s c o u r i n g , 3 7 7

- , - - , t e x t i l e a u x i l i a r i e s , 3 7 9, , w o o l s c o u r i n g , 3 7 8

- , f r o m o z o n d e p l e t i o n , 3 9 0

- , - , u v r a d i a t i o n , 3 9 0

, , , a b s o r p t i o n , 3 9 0

, , , p r o t e c t i o n , 3 91

P o t e y e s , 2 4 1

P o t t i n g o f w o o l l e n f a b r i c s , 1 1 0

Q u a l i t y c o n t ro l , 4 0 4

Q u i n a f i b r e , 3 4

R a y o n ,

- , c e l l u l o s e a c e t a t e , 2 5

-, c u p r a m m o n i u m , 2 2

-, r e g e n e r a t e d c e l l u l o s e , 2 3- , - - , a ce t a t e , 25 , 26

- , - , p r o t e i n , 2 0

R e a c t i v i t y o f m e r c e r i z e d c o t to n , 2 9 0

R e c o - y e t , 3 4 8

R e d u c t i v e b l e a c h i n g o f ,

- - -, n y l o n , 1 9 5

- - - , s i l k , 194

- - - , w o o l , 1 9 2

, , w i t h s o d i u m b i s u l p h i t e , 1 93

, , , s o d i u m h y d r o s u l p h i t e , 1 9 3

, , , s u l p h u r d i o x i d e , 1 9 2

, , , t h i o - u r e a d i o x i d e , 1 9 4

R e l a x a t i o n o f ,

- - , t e x t u r e d n y l o n , 1 2 1

- -, -, p o l y e s t e r , 1 2 4- - , a c r y l o n i t r i l e f i b r e s , 1 2 2




- -, w o o l , 1 1 0

R e l a x i n g m a c h i n e s , 4 4

R e m i e , 1 8

-, d e g u m m i n g o f , 1 16

R e m o v a l o f i m p u r i t i e s ,

- - - , f r o m c o t t o n , 8 7 , 8 8

R e t t i n g o f ,

- - , f l a x , 1 7

- -, r e m i e , 1 9

- - , j u t e , 1 9

R e v e r s e o s m o s i s , 3 8 6

R o p e ,

- , d e t w i s t e r , 2 4 5

- , e x p a n d e r , 2 4 5 , 2 4 6

- , p i l e r , 2 1 8 , 2 4 4

- , s q u e e z i n g , 2 4 4

S a r a n , 3 9

S a n f o r s e t , p r o c e s s , 3 0 9

-, r a n g e , 3 1 1

S a p o n i f i c a t i o n o f w a x , 3 9

S c o u r i n g o f ,

- -, b l e n d e d f a b r i c s , 1 2 5

- - , c o t t o n , 8 9

- - , c o l o u r e d w o v e n g o o d s , 9 4

- - , J u t e , 1 2 0

- -, l i n e n , 1 1 9

- -, r a w w o o l , 1 0 7

- -, s y n t h e t i c f i b r e s , 1 2 0

- -, t e x t u r i s e d f a b r i c s , 1 2 3

- -, w o o l y a r n a n d f a b r i c , 1 0 9

S c o u r i n g o f b l e n d e d f a b r i c s ,. . . . , a c e t a t e / w o o l , 1 2 8

. . . . , a c r y l i c / c e l l u l o s e , 1 2 7

. . . . , a c r y l i c / w o o l , 1 2 7

. . . . , c o n t a i n i n g c a s e i n , 1 2 9

, , v i s c o s e , 1 2 8

. . . . , p o l y e s t e r / a c r y l i c , 1 2 7

. . . . , p o l y e s t e r / c o t t o n , 1 2 5

. . . . , p o l y e s t e r / s i l k , 1 2 9

. . . . , p o l y e s t e r / w o o l , 1 2 6

S c o u r i n g o f c o t t o n w i t h ,

. . . . , a l k a l i n e a g e n t s , 8 9 - 9 4

. . . . , b l e n d e d s u r f a c t a n t s , 9 9

. . . . , c a u s t i c s o d a b o i l , 8 9

. . . . , e m u l s i o n p r o c e s s , 1 83

. . . . , l i m e - s o d a b o i l , 8 9

. . . . , m i x e d a l k a li , 9 0

. . . . , s o d a - a s h , 9 0

. . . . , s o a p / s o d a b o i l , 9 0S c o u r i n g e f f i c ie n c y , d e t e r m i n a t i o n b y ,

, , D r a v e s t e s t, 4 5 2

, , w a x c o n t a n t , 4 5 2

, , w e i g h t l o s s , 4 5 2

S c o u r i n g m a c h i n e s ,

- -, b a t c h , r o p e , 1 3 2

- - , - , j ig , 1 3 7

- -, - , p a d d l e , 1 2 5

- -, -, r o t a r y d r u m , 1 2 5

- -, - , o p e n - w i d t h , 1 3 5

- -, s e m i - c o n t i n u o u s , 1 3 8

- -, c o n t i n u o u s , 1 3 8

-- , - , c o n v e y e r s y s t e m , 1 4 2

- - , - , J - B o x , 1 3 8

- - , - , s t e a m e r , 1 3 8- -, - , V a p o r l o c , 1 4 0




- -, w i t h r e l a x i n g , 1 4 2

- - , i n s o l v e n t , 1 4 4

S c o u r i n g o f w o o l,

- - -, e m u l s i o n , 1 0 8

- - -, m u l t i - s t a g e , 1 0 8

- - - , r a w , 1 0 7

- - -, r e f r i g e r a t i o n , 1 0 9

- - - , su in t , 1 0 9

S c o u r i n g m a c h i n e f o r w o o l ,

. . . . , f a b r i c , 1 4 9

. . . . , F l e i s s n e r , 1 4 6

. . . . , h a n k , 1 4 7

. . . . , j e t , 1 4 6

. . . . , L o - f l o , 1 4 7

. . . . , r a w w o o l , 1 45

S c r o o p i n g , 1 1 8

S c r o l l r o l l e r , 2 4 5S c u t c h e r , 2 4 5

S e r i c i n , 1 4 , 1 7 8

S e m i - c o n t i n u o u s b l e a c h i n g e q u i p m e n t ,

- - -, p a d - b a t c h , 2 2 2

- - - , p a d - r o l l , 2 2 3

- - - , p a d - j i g , 2 2 4

S e m i - c o n t i n u o u s s c o u r in g e q u i pm e n t ,

- - - , p a d - r o l l , 1 2 8

, , p e r f o r a t e d c y l i n d e r , 1 3 6

- - -, p a d - s t e a m - r o l l , 1 3 8

S e m i - m e r c e r i z a t i o n , 2 8 9

S e t t i n g o f w o o l l e n f a b r ic , 1 1 0

S e q u e s t e r i n g a g e n t ,

- - , c h e m i c a l s t r u c t u r e s , 9 1

- -, e f f e c t o f p H , 9 2- -, m e c h a n i s m o f a c t io n , 9 5

- - , o r g a n i c , 9 2

- - , - o r g a n o p h o s p h a t e s , 9 3- - , i n s c o u r i n g , 9 1

, , fu n c t i o n o f , 9 1

S e q u e n t i a l b l e a c h i n g o f ,

- - - , j u t e , 1 9 8

- - - , w o o l , 1 2 6

Si lk ,

-, d e g u m m i n g , 1 15

- , g u m c o n t e n t , 1 15

- , i m p u r i t i e s , 1 1 5

- , p h o t o m i c r o g r a p h o f, 1 1 4

S i l k b l e a c h i n g w i t h ,

- -- , h y d r o g e n p e r o x i d e , 1 78

, , p r o c e s s , 17 9

, , r ec ip e , 1 7 9

- - - , - - , s t ab i l i se r s , 1 7 9S i lk d e g u m i n g m a c h i n e s ,

- -- , c o n t i n u o u s , 1 5 7

- - - , p i e c e g o o d s , 1 5 7

- - - , s t a r , 1 5 7

S i n g e i n g o f f a b r ic s ,

- - -, b l e n d e d , 6 7

- - - , k n i t t e d c o t t o n , 6 3

- - -, p o l y e s t e r , 5 7

- - - , v e g e t a b l e f i b r e s , 5 6

- - - , w o o l , 5 6

S i n g e i n g m a c h i n e s ,

- - , g a s , 5 6 - 6 0

- - , g a s r a n g e , 6 2

- - , k n i t t e d f a b r i c s , 6 4

- - , p l a t e , 5 7- -, p o s i t i o n o f b u r n e r , 6 1




- -, r o t a r y c y l i n d e r s , 5 8

S i l v e r n i t r a t e t e s t , 4 6 2

S i z e s ,

- , a n a l y s i s o f , 4 5 1

- , i d e n t i f i c a t i o n o f , 4 4 9

-, f o r f il a m e n t y a m , 4 4 8

- , - , s p u n y a m , 4 4 9

S o a p , 9 6

S o d i u m b i s u l p h i t e ,

- - , a n a l y s i s o f , 4 5 7

- -, b l e a c h i n g o f w o o l , 1 93

S o d i u m c h l o r i t e b l e a c h i n g ,

- - - , a c e t a t e f i b r e s , 1 8 5

- - - , a c r y l i c f i b r e s , 1 8 5

- -- , a c t i v a t i o n , 1 8 3 - 1 8 5

- -- , a n a l y s i s o f , 4 5 6

- - - , c o t t o n , 1 8 3- -- , d a m a g e o f c o tt o n , 1 8 2

- - - , j u t e , 198

- -- , m e c h a n i s m o f , 1 82

- -- , m e r i t s a n d d e m e r i t s , 1 8 7

- - -, n y l o n , 1 8 4

- -- , p o l y e s t e r , 1 8 4

- -- , p o l y v i n y l a lc o h o l , 1 8 6

- -- , p r o b l e m s o f c o r r o s i o n , 1 8 6

S o d i u m h y p o c h l o r i te b l e a c h in g

- - -, a c c e l e r a t e d , 1 6 6

- -- , a n a l y s i s o f , 4 5 6

- -- , c a t a l y t i c a c c e l e r a t i o n , 3 5 1

- - - , c o t t o n , 1 6 5

- - -, d e c o m p o s i t i o n o f , 1 05 , 1 63

- - - , f a c t o r s e f f e c t i n g , 1 6 4- - - , i n d a n g e r z o n e , 1 6 6

, , c o n j u c t i o n w i t h H202, 166

, , p r e s e n c e o f a d d i t i v e s , 1 6 7

, , s t e a m i n g p r o c e s s , 1 6 7

- - - , m e r i t s a n d d e m e r i t s o f , 1 6 8

- -- , p r e p a r a t i o n o f , 1 6 2

- - -, r a t e o f a t t a c k , 3 5 0

- -- , r e a c t i o n s p e c i e s , 3 5 2

, , w i t h c e l l u l o s e , 3 5 2 , 3 5 3

S o d i u m s i l i c a t e ,

- - , a s s t ab i l i s e r , 17

- - , i n k i e r b o i l i n g , 8 9

S o i l r e p e l l e n c y , 4 1 1

S o l a r h e a t i n g , 3 4 2

S o l v e n t ,

- , b o o s t e r , 1 0 6

- , d i f f i c u l t i e s , 107

- , d e t e r g e n t s , 1 0 6- , d e s i z i n g m a c h i n e , 8 3

- , s c o u r i n g , 1 0 6 , 1 0 8

- , - , m a c h i n e , 1 4 4 , 1 4 5

- , - , o f w o o l , 1 0 9

- , - , w i t h t r i c h l o r o e t h y l e n e , 1 2 7

S p i n f i n i s h i n g a g e n t s , 1 0 4

S t a r c h , 6 9 , 7 0

- , l i q u i f y i n g e n z y m e s , 7 3

S t a b i l i s e r s ,

- , a n a l y s i s o f , 4 5 7

- , b l e a c h i n g s i lk , 1 7 9

- , - , w o o l , 1 7 4

-, f o r h y d r o g e n p e r o x i d e , 1 6 9 , 1 7 0 , 1 72

- , - , s o d i u m c h l o r i te , 1 6 3

, , , a n a l y s i s o f , 4 6 8- , a s s e q u e s t r a n t s , 1 7 1 , 1 7 2




- , - , s o d i u m s i l i c a t e , 3 5 3

S t a b i l i s a t i o n o f w o o l , 4 0

S t a b i l i s e d h y d r o s u l p h i t e , 1 9 2

- - , a n a l y s i s o f , 4 5 7

S t a in r e m o v e r ,

- -, e m u l s i o n s c o u r i n g , 1 05

- - , e m u l s i f i e d s o l v e n t s , 1 05

- - , o x a l i c a c i d 1 0 6

S t e am e r , 8 2, 2 3 1 , 2 3 6

S t e a m c o n s u m p t i o n , 3 6 5

S t e n t e r , 2 6 0

S t e ro s t ru c t u r e o f p o l y p r o p y l e n e , 3 8

S t o v i n g p r o c e s s , 1 9 2

- - , d i s a d v a n t a g e o f , 1 9 3

S t o n e w a s h i n g , 4 3 1

S t r u c t u r e o f c o t t o n , 4

-- , s i lk , 14- - , w oo l , 11

S u i n t i n w o o l ,

- - - , cons t i tu t ion o f , 13 , 14 , 107

- - - , s c o u r i n g , 1 0 9

S u l p h u r d i o x i d e ,

- - , b l e a c h i n g o f s il k , 1 9 4

- - , b l e a c h i n g o f w o o l , 1 9 2

S u l p h u r o u s a c i d , 1 9 3

S u r f a c e a c t i v i t y , i n w a t e r , 1 0 0

S u r f a c e t e n s i o n , 9 4 , 1 0 0 , 1 0 3

S u r f a c t a n t s ,

- , a m p h o t e r i c , 9 8

- , a n i o n i c , 9 5

- , b l e n d s , 9 9

- , c a t i o n i c , 9 6- , c l a s s i f i c a t i o n o f , 9 5

- , c l o u d p o i n t , 9 8

- , H L B , 9 5-, n o n - i o n i c , 9 7

- , a s de te rgen t s , 101

- , - , emuls i f i e r , 103

- , - , s cour ing agen ts , 101

- , - , w e t t i n g a g e n t s , 9 9

- , i n s y n t h e t i c f i b r e s c o u r i n g , 9 5

- , - , w o o l s c o u r i n g , 9 5

T a l l o w ( T r i g l y c e r id e s ) , 8 7

- , e v a l u a t i o n o f , 4 4 6

T a p e s c o u r i n g m a c h i n e , 1 2 7

T e n d e r i n g o f c o t to n , 3 5 4

- , d u r i n g b l e a c h i n g w i t h b r o m i t e , 3 4 5

, , h y d r o g e n p e r o x i d e , 3 5 3 , 3 5 4

, , h y p o c h l o r i t e , 3 5 0 - 3 5 2- , - - , w o o l , 3 5 5

- , d u r i n g c a r b o n i s i n g o f w o o l , 3 5 5

- , - , d e s i z i n g , 3 4 4

- , - , s c o u r i n g , 9 4 , 3 4 6 , 3 5 0

T e n d e r i n g o f ,

- - , s i lk , 356

- - , - , d u r i n g d e g u m m i n g , 3 5 6

- - , p o l y e s t e r , 3 5 7

- - , w o o l , 3 5 4

- - , - , a s s e s s m e n t o f , 4 6 3 - 4 6 4

, , m i c r o s c o p i c t e st , 4 6 3

, , so lu b i l i ty t e s t , 463

, , sw e l l in g t e s t , 463

T e n d e r i n g o f c o t to n , d e t e r m i n a t i o n o f ,

, , a c i d i c g r o u p , 4 6 2, , c o p p e r n u m b e r , 4 6 0




, , f l u i d i t y , 4 5 8

, , m e t h y l e n e b l u e , a b s o r p t i o n , 4 6 1

, , s i l v e r n i t r a t e t e s t , 4 6 2

T e n t e r i n g , 2 6 0

T e m p o r a r y h a rd n e s s , 3 61

- - , a n a l y s i s o f , 4 4 2

T e x t o n e , 1 8 2

T e x t u r e d f a b r ic ,

- - , h e a t - s e t t i n g o f , 2 6 0

- -, r e l a x a t i o n o f , 1 2 4

- - , s c o u r i n g o f , 1 2 3

T e x t u r e d y a m s ,

- - , s p i n f i n i s h e s , 1 2 4

, , r e m o v a l of , 1 2 4

T h e r m o s e t t i n g , 2 5 6

T h i o u r e a

- , d i o x i d e , 1 7 7 , 1 9 2 , 1 9 4- , r e d u c t i v e b l e a c h i n g , 1 76

T h r o w i n g o f s il k , 1 15

T r i a c e t a t e , 2 5

T r i c h l o r o e t h y l e n e , 1 0 6 , 1 2 7

T r i t h i o c y a n u r i c a c i d , 1 7 7

T u s s a h s i l k , 1 7 8

U l t r a f i l t r a t i o n m e t h o d , 3 8 8

U l t r a m a r i n e b l u e , 1 8 0 , 3 2 0

U n s a p o n i f i a b l e m a t t e r ,

- - - , a n a l y s i s o f , 4 4 7

u v r a d i a t io n , 3 9 0

- -, p r o t e c t i o n f r o m , 3 9 1 , 3 9 2

- - , s u r f a c e c o a t i n g , 4 1 4

V a p o r l o c m a c h i n e , 1 40

V a p o u r p h a s e t r e a t m e n t , 4 1 4

V e g e t a b l e f i b r e s , 1 6

- -, c h e m i c a l c o m p o s i t i o n o f , 1 6- 21

V i c a r a , 2 2

V i n y o n , 3 9

V i s c o s e p r o c e s s , 3 9

V i s c o m e t e r f o r f l u id i t y , 4 5 9

V i s c o s i t y , 3 5 0

W a s h i n g o f ,

- -, d e g u m m e d s i lk , 1 1 8

- - , s c o u r e d g o o d s , 9 1

W a s h i n g m a c h i n e s ,

- - , r o p e , h i g h s p e e d , 2 4 1

, , s l a c k , 2 4 2

- - , - , s q u a r e b e a t e r , 2 4 3

- - , - , t i g h t , 2 4 9- -, o p e n - w i d t h , a q u a t e x , 2 5 3

- - , - - , B e c o f l e x , 2 5 3

, , B e n - e x t r a c t a , 2 3 0

, , c o u n t e r - c u r r e n t , 2 5 4

, , h o r i z o n t a l , 2 5 5

, , j e t , 2 5 0

, , o p e n s o a p e r , 2 5 2

, , , w i t h b e a t e r , 2 5 2

, , r o l l e r c o n v e y e r , 2 5 1

, , R o t o w a , 2 4 9

- - , - - , - , r a n g e , 2 5 0

- - , - - , s p r a y d r u m , 2 5 0

, , s u c t i o n d r u m , 2 4 7

, , , r a n g e s , 2 4 8

W a s t e w a t e r ,- - , a c t i v a t e d s l u d g e , 3 8 5




- - , a s s e s s m e n t o f , 3 7 2

- - , i n c i n e r a t i o n o f , 3 9 0

- -, p o l l u t i o n , 3 7 0

- - , - , l o a d , 3 7 4

- -, m a n a g e m e n t a c t iv i ty , 3 82

- - , t o l e r a n c e l i m i t , 3 7 3

- - , t r e a t m e n t p l a n t , 3 8 0

W a s t e w a t e r p o l l u t io n f r om ,

. . . . , a u x i l i a r y e f f l u e n t s , 3 7 9

. . . . , b l e a c h i n g e f f l u e n ts , 3 7 8

. . . . , d e s i z i n g e f f l u e n t s , 3 7 6

. . . . , s c o u r i n g e f f l u e n ts , 3 7 7

W a s t e w a t e r , r e c o v e r y o f ,

, , c a u s t i c s o d a , 3 8 6

, , s i z i n g a g e n t s , 3 8 6

, , s i z e m i x t u r e s , 3 8 9

, , p o l y v i n y l a l c o h o l , 3 8 7- -, t r e a t m e n t s , 3 8 0

, , t e r t i a r y , 3 8 5

, , b y h y p e r f i l t r a t i o n , 3 8 6

, , , p r e c i p i t a t i o n a n d c o a g u l a t i o n , 3 8 3

, , , r e m o v a l o f i n o r g a n i c m a t t e r , 3 86

, , , o r g a n i c m a t t e r , 3 8 6

- - - , p lan t , fo r wo o l scou r ing e f f luen ts , 384 .

W a t e r ,

- , a l k a l i n i t y , 3 6 1

- , a n a l y s i s o f , 4 3 5

-, c o n s u m p t i o n o f, 2 49 , 3 6 0

- , d i s s o l v e d m a t t e r , 3 6 2

- , h a r d n e s s , 4 3 6 , 3 6 2

- , t u r b i d i t y o f , 3 6 2

- , f o r b o i l e r , 3 6 2-, m a n g l e , 2 4 6

- , m e t a l c o n t e n t , 3 6 1

- , s t r u c t u r e , 1 O 0

-, p u r i f i c a t i o n p r o c e s s ,

, , b a s e e x c h a n g e , 3 6 4

- , - - , l i m e - s o d a , 3 6 3

, , s o d a - a l u m , 3 6 3

W a l s h ' s k i e r , 1 33

W a x / e s ,

- , a c i d v a l u e , 4 4 7

- , a l c o h o l , 7

- , c h e m i c a l n a t u r e , 1 3

-, c o n t e n t , e v a l u a t i o n o f , 4 3 9 - 4 4 1

- , - , i n c o t t o n , 5 , 6 , 8 7 , 8 8

, , , c o m p o s i t i o n o f , 7

, , , e v a l u a t i o n o f , 4 4 5

- , - , i n f l a x , 1 7

, , , s i l k , 14, , , w o o l , 1 0 , 1 3 , 1 0 7

- , i o d i n e v a l u e , 4 4 1

-, s a p o n i f i c a t i o n v a l u e , 8 9

, , e v a l u a t i o n o f , 4 4 9

-, u n s a p o n i f i e d m a t t e r , 4 4 6

W e f t k n i t t e d f a b r i c s ,

- - - , b l e a c h i n g o f , 2 0 9

- - - , m e r c e r i z a t i o n o f , 3 0 3

- - - , s i n g e i n g o f , 6 3

W e t t i n g a g e n t s , 9 9

W e t t i n g o f t e x t il e s , 9 5 , 1 O 0

W h i t l e r r o p e r e g u l a t o r , 2 4 6

W i l d s i l k ,1 4

- -, b l e a c h i n g o f , 1 7 9

W o o l ,- , a c t i o n o f s t e a m , 1 1 0




- , a m i n o a c i d c o n t e n t o f , 1 2

- , b u r r s , 1 0 7 , 1 0 3 , 1 0 4

- , c a r b o n i s i n g , 1 1 0 - 1 1 3

- , c h e m i c a l c o m p o s i t i o n o f, 1 2

- , c o r t e x , 9 , 1 0

- , c r i m p , 8

- , c u t i c l e , 9

- , d e g r a d a t i o n , 4 4 , 3 5 4

- , - , a s s e s s m e n t o f , 4 6 3 , 4 6 4

-, d i s u l p h i d e e x c h a n g e , 1 1 1 , 11 2

- , - , r u p t u r e , 4 5 7

- - , y a r n , 1 0 9

- - , - , b a t t r i c e m a c h i n e , 1 4 8- - , - , ta p e m a c h i n e , 1 4 8

- - , f a b r i c , 1 1 3

, , D o l l y , 1 4 9

- - , - , r a p i d , 1 5 0

W o o l s c o u ri n g m a c h i n e ,

- - -, c o n v e n t i o n a l , 1 4 5

- - -, F l e i s s n e r , 1 4 6

- - - , j e t , 1 4 6

- - - , L o - f l o , 1 4 7

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