Indian Journal of Textile ResearchVol. 14, March 1989, Pp, 39-44

Effect of thickener film structure on dye release during sublimation transferprinting of polyester

R B Chavan & A K JainDepartment of Textile Technology, Indian Institute of Technology, New Delhi 110 016, India· ,/

Received 21 July 1988; revised and accepted 1 September 1988

An attempt has been made to highlight the importance of the structure of the thickener filmon dye re-lease during sublimation transfer printing of polyester. Indalca AGBV when used alone as a printingthickener gave a continuous film in which the dye was embeded. This film acted as a barrier to the releaseof dye from paper, resulting in low dye transfer. The dye transfer, although low, was dependent on thedye particle size and the thickness of the wet film deposits. The incorporation of a suitable auxiliary in In-dalca AGBV thickening disrupted the continuity of the thickener film and enhanced dye transfer. Thedye particle size and film thickness of Indalca AGBV lost their significance in the presence of a suitableauxiliary in the print paste./

,/

Keywords: Auxiliary, Disperse dye, Indalca AGBV, Polyester, Transfer printing

1 IntroductionThe sublimation transfer pnntmg process in-

volves the transfer of dye in the vapour form frompaper to the fabric. The process is ideal for transferprinting 100% polyester. In this process, the follow-ing two parameters playa vital role in governing thedye transfer: (i) release of dye from the thickenerfilm, and (ii) affinity of substrate for dye vapours re-leased from the thickener film.

Several workers I - 5 highlighted the various fac-tors governing the release of dye from the thickener.In the work reported by Hawkyard I, the initialprinting with C.I. Disperse Red-60 was carried outon polyester film using hydrophilic thickeners likesodium alginate, carboxymethyl starch and hydroxyethylated guar gum. The dye was transferred at200°C for 30 s. This operation was considered to besimilar to transfer printing on polyester where theair gap between the dye on paper and the fabric wasreduced to zero. He observed that among the threethickeners used carboxymethyl starch gives thehighest dye transfer followed by hydroxy ethylatedguar gum and sodium alginate. The difference in thebehaviour of thickeners was explained on the basisof the structure and dye distribution in the thickenerfilm. He concluded that in the case of carboxyme-thyl starch the heterogeneous distribution of dyeparticles allows the dye vapour to escape freely dur-ing thermofixation and thus gives high dye fixation.Any auxiliary which will break the continuity of thethickener film will result in better dye release.

Detscheva et al.2,3 carried out the investigationson thickenings based on sodium alginate, starchether, locust bean gum ether and combination ofstarch ether, sodium alginate and emulsion (2:1 :0.5).They incorporated caprolactum as an additive tothe various thickenings and opined that the additionof caprolactum increases the amount of dye fixed inall types of thickeners.Their findings indicated thatthe dye fixation was rapid in the case of combinationthickener followed by alginate thickener ManutexRS-5, Solvitose C5 and Indalca PA3. They con-cluded that the film of the combination thickenerwas more porous which resulted in highest and rap-id dye fixation.

Biedermann and Ischi" highlighted the factorsgoverning the dye transfer onto polyester film usingsodium alginate thickener alone and in presence offixation accelerants. On the basis of semiquantita-tive evidence they showed that the alginate thicken-ers can envelope the disperse dye particles, givinglow dye fixation. The incorporation of fixation ac-celerants disturbed the structure of the thickenerfilm and formed a system of channels through whichthe dye could diffuse to the substrate and thus gavehigh dye fixation. Chavan and Hanif" incorporatedvarious auxiliaries to the carboxymethyl cellulosethickener to study the release of disperse dyes frompaper during transfer printing of resin-treated cot-ton fabric. They observd that carboxymethyl cellu-lose thickener gives a continuous film on the paperwhich hinders the transfer of dye from paper to the

39

INDIAN J TEXT RES, MARCH 1989

fabric. However, the incorporation of auxiliarieslike Lissapol-N, PVAc and foaming agent favou-rably modified the structure of CMC thickener filmand so high dye transfer could be obtained. Theysupported their findings using scanning electron andoptical microscopes.

In the present work, an attempt has been made tohighlight the importance of the structure of IndalcaAGBV thickener film in governing dye release dur-ing sublimation transfer printing of polyester. Theeffects of concentration of dye, dye particle size anda suitable auxiliary in Indalca AGBV thickening ondye transfer have been investigated.

2 Materials and Methods

2.1 Materials

2.1.1 FabricCommercially bleached but unfinished 100% po-

lyester fabric of 65 g/m? was used.

2.1.2 DyesTwo samples of c.!. Disperse Red-11, one com-

mercially available and another purified by soxhletextraction using acetone (to get the increased dyeparticle size), were used.

2.1.3 Transfer PaperDuplicating paper (72 g/m-) was used.

2.1.4 ThickenerGum Indalca AGBV supplied by Indian Gum In-

dustries Ltd, Bombay, was used as a printing thick-ener.

2.1.5 AuxiiiariesThe following auxiliaries were used.(i) Kerosene-water emulsion.(ii) Foaming agent containing the stabilizer (sup-

plied by HICO Products Ltd, Bombay, under thetrade name of Product FMPW).

(ill) Non-ionic auxiliary based on fatty alcohol-ethylene oxide condensate, cationic auxiliary basedon quaternary ammonium compounds and an an-ionic auxiliary based on sulphated fatty alcohols(supplied by Ahura Chemical Products Ltd, Bom-bay, under the trade names of Softnol NBT, Cata-softener and Finish XUIW respectively).

2.2 Methods

2.2.1 Gum Indalca ThickeningGum Indalca AGBV (6%) was prepared in cold

water.

40

2.2.2 Printing of PaperThe paper was printed using K-hand bar coater

'supplied by R.K. Print-Coat Instruments Ltd, Eng-land, with a print paste composition containing dis-perse dye (4%) and gum Indalca AGBV (6% thick-ening) alone or gum Indalca AGBV with a suitableauxiliary depending on the experimental needs. Theprinted paper was then dried at room temperatureand used for transfer printing on polyester fabric at200°C for 1 min using manual heat transfer printingpress supplied by A. Adkins and Sons Ltd, England.

2.2.3 Estimation of Dye TransferThe dye transfer on polyester fabric was deter-

mined by extracting the dye in 15 ml of hot N,N-dimethyl formamide (DMF) acidified with 2.5 ml of1 N HCI from equal areas of untransferred andtransferred paper. The extracts were then cooled atroom temperature and made to 25 ml with DMF.The optical densities of the extracts were measuredon a Pye Unicam SP-600 spectrophotometer at thewavelength of maximum absorption. The % dyetransfer on the polyester fabric was estimated fromthe differences in optical densities.

2.2.4 Determination of Dye Particle SizeThe dye particle size was determined on rnicro-

photo sizer supplied by SEISHIN, Japan, using lightscattering technique.

2.2.5 PhotomicrographsThe photomicrographs were obtained by coating

the transparent PVC sheet with suitable print pastecomposition, drying it at room temperature andthen viewing it under the projectina microscope.

3 Results and DiscussionSeveral. workers 1 - 5 studied the transfer of dis-

perse d~e from a support to a substrate and ob-served that thickeners act as barrier and hinder therelease of dye from the support. Hence, suitable ad-ditives are needed to break the continuity of thethickener film and thus offset the hindrance to thedye release.

3.1 Barrier Action of Thickener FilmTo study this effect, the papers were printed with

4% dye in Indalca AGBV thickener (6%) usingK-hand bar number 3-8 which gave the wet filmthickness of 24-100 urn. The papers were then dri-ed at room temperature. The transfer printing ofpolyester fabric was carried out at 200°C for 1 min.The effect of gum Indalca AGBV film thickness ondye transfer is shown in Table 1. It is seen that thedye transfer in both the samples is unsatisfactory

CHAVAN & JAIN: EFFECT OF THICKENER FILM STRUCTURE ON DYE RELEASE

Table I-Effect of gum Indalca AGBV film thickness ondye transfer

K-bar Thickness Transfer of Disperse Red-II (%)No. of wet film

deposits Commercial dye Purified dye!lm

Relative Absolute Relative Absolute

3 24 22.7 5.0 35.9 11.04 36 16.0 4.8 28.9 10.05 50 13.6 4.9 23.9 9.96 60 12.0 5.0 20.0 9.77 75 9.3 4.5 16.6 10.08 100 8.6 4.8 12.0 10.7

from the commercial point of view and it decreasesconsistently with increase in the thickness of wetfilm. Although, the per cent transfer of the dye dec-reases with the increase in film thickness, the abso-lute dye transfer is more or less constant irrespec-tive of the film thickness. The poor dye transfer isobviously because of the barrier action of IndalcaAGBV which is also supported by the work ofHawkyard", Biedermann and Ischi", The constancyof the absolute dye transfer with the variation in thefilm thickness indicates that only the dye at the in-terface is available for transfer. To prove this, we topcoated the printed paper with Indalca AGBV thick-ener alone using K-bar No.3. The effect of numberof top coatings on dye transfer is shown in Fig. 1. Itis seen that with the increase in the number of coat-ings, the dye transfer decreases considerably, i.e.from 22.7% to 0.9%. The dye transfer, thoughsmall, may be attributed to the migration of dye atthe interface during drying which would decreasewith the increase in the number of top coatings.

3.2 Effect of Dye Concentration on Transfer

Table 1 shows that the dye transfer of purified C!.Disperse Red-II is higher at all the thicknesses thanthat of the commercial C!. Disperse Red-ll. It maybe either due to the higher colour concentration ofpurified dye or due to its bigger particle size. To findout the effect of dye concentration on transfer, dif-ferent concentrations (2-12%) of commerciallyavailable C!. Disperse Red-ll were incorporated inIndalca AGBV thickening. The paper was printedusing K-bar No.3 and dried at room temperature.The transfer printing of polyester fabric was carriedout at 200°C for 1 min. The results of dye transferare shown in Fig. 2. It is clear from the figure that thedye transfer remained constant irrespective of theconcentration of dye in the printing paste, indicatingthat the bigger dye particle size of purified dye is

25

crwu,I/')

Z4:crI-

W>a

3 4

TOP <XlATINGSOF I NDALCA AGBV

Fig. I-Effect ofIndaica AGHV top coatings on dye transfer

~.-----------------------~a: 30w~zCl 20•..w~ 10

• • •• ••

o~~ __ -+__~ __~ __~ __~~o ,2 10 12 14

CONCENTRATION OF DYE I ~)IN INDALCA AGBV TItCKENING

Fig. 2-Effect of dye concentration in Indalca AGBV thickeningon dye transfer

responsible for its higher transfer and not its highercolour concentration.

3.3 Effect of Dye Particle Size on TransferBiedermann and Ischr' correlated the amount of

surface dye with the dye particle size. They were ofthe opinion that the amount of dye present at the in-terface will increase with the increase in the particlesize. They also pointed out the significance of the dJlratio (where d is the diameter of dye particle and l,the thickness of wet film) and suggested that thehighest transfer could be achieved when the dJl ratioapproaches 1. We determined the particle size ofboth the samples on microphotosizer. The resultsare given in Table 2. The table shows that the parti-cle size of commercial dye is in the range of 1-5 umwhereas the particle size of purified dye has a widedistribution in the range of 1-20 urn, The minimumthickness of the coating with K-hand bar-3 was 24urn. Taking the analogy of Biedermann and Ischi'swork, the dJl ratio in the case of commercial samplewas much smaller compared to that in the case ofpurified dye. Therefore, the amount of purified dyeparticles available at the interface would be greaterwhich is reflected in higher dye transfer at all the

41

INDIAN J TEXT RES, MARCH 1989

Table 2-Particle size of C.I. Disperse Red-Ll

Range of Particles (% wt)particle

size11m

0~11~22~33~44~55~66~77~88~99~10

1O~1l11 ~ 1212 ~ 1313 ~ 1414~1515 ~ 1616 ~ 1717 ~ 1818 ~ 1919 ~20

Commercialdye

63.5028.66

4.631.611.61

0.000.000.000.000.000.000.000.000.000.000.000.000.000.000.00

Purifieddye

15.7012.3210.41

6.876.870.110.110.110.110.114.254.254.254.254.255.205.205.205.205.20

thicknesses (Table 1). This experiment clearly indi-cates that the thicknesses of Indalca AGBV depositsarrest the dye particles of very low size and only theparticles available at the interface are transferred tothe fabric during the transfer printing operation.This was revealed when we calculated the absolutedye transfer which remained more or less constantat all the coating thicknesses.

3.4 EtJect of Auxiliaries in Gum IndaIca on Dye TransferThe following auxiliaries were incorporated in the

Indalca AGBV thickening: emulsion thickener(kerosene-water emulsion), foaming agent, non-ionic auxiliary, cationic auxiliary and anionic auxil-iary. The incorporation of these auxiliaries im-proved the dye transfer considerably (Figs 3 and 4).It is clear from these figures that me dye transfer in-creased with increase in the concentration of auxili-aries till a certain concentration range where it re-mained constant and then it decreased with furtherincrease in the concentration of auxiliaries. Amongthe various auxiliaries the anionic auxiliary gave thehighest dye transfer. Moreover, the printing of pa-per was quite smooth and uniform with this auxil-iary. Incorporation of 5-10% anionic auxiliary in In-dalca AGBV thickening gave the highest dye trans-fer. We selected 7.5% as an optimum concentrationof the anionic auxiliary to be incorporated in the In-

42

.....---------------,

••51

AUXILIARY( .•..•..• ) Non-ionk(..•....•.• ) Cationic(-0-00) Anionic

·.~-~~-~-~~~-~~1~.~16

CO!ICUTWIlII Of AUXllI'.v 1%1

Fig. 3-Effect of concentration of auxiliaries in Indalca AGBVthickening on dye transfer

10.--------------,70

60

It:SO,..1L.n~ 40It:0-

W

is )0

20k>oo-) Indalca AGeV/Foamlhick •••••.1000 ) Indalca AG8'I/Emullion lhick_

10

~~·~~--=7s~/2~S-~S~0~/~~-~2S~/~7S~~OP"GI/FOAM OR EMULSION THICKENERCCI1POSIT1OH1°1.)

Fig. 4-Effect on concentration of auxiliaries in Indalca AGBVthickening on dye transfer

dalca AGBV paste. Subsequently, we studied the ef-fect of the thickness of the wet film on dye transferwith the following print paste compositions:

Disperse Red-II (both commercial andpurified dye samples) 4%Anionic auxiliary 7.5%Gum Indalca AGBV (6%) 88.5%

The results of dye transfer are shown in Table 3. It isobserved from the table that the % dye transfer re-mains constant (68-69.5%) irrespective of the thick-ness of the wet film and dye particle size. The abso-lute transfer obviously increased with the increase inthe coating thickness. To give the possible explana-tion, we took the photomicrographs of IndalcaAGBV + 4% dye and Indalca AGBV + 7.5% anionicauxiliary +4% dye printed on PVC sheet under theprojectina microscope (Fig. 5). The figure shows

CHAVAN & JAIN: EFFECf OF TIIICKENER FILM STRUcruRE ON DYE RELEASE

Table 3-Effect of gum Indalca AGBV + 7.5% anionic auxiliaryfilm thickness on dye transfer

K-bar Thickness Transfer of Disperseof Red-ll (%)

wet filmdeposits

Ilm2436506075

100

No.

34

5678

Commercialdye68.869.4

68.568.369.569.0

Purifieddye69.068.168.368.569.569.0

that the incorporation of an anionic auxiliary creat-ed circular voids in Indalca AGBV which disruptedthe continuity of the thickener film, making it morepermeable to the release of dye vapour. However, athigher auxiliary concentration, the dye solubility inthe auxiliary might be more predominant, facilitat-ing the dye diffusion in the paper and thus reducingthe dye transfer on fabric. The above findings showthat the incorporation of an auxiliary eliminated thebarrier action of Indalca AGBV, resulting in betterdye release. The dye particle size and the thicknessof wet film lost their significance in presence of an-ionic auxiliary in governing the dye release.

Fig. 5-Pho\omicrograph of (a) Indalca AGBV+ 4% dye( x 200). and (b) Indalca AGBV+ 4% dye + 7.5% anionic auxili-

ary ( x 200)

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INDIAN J TEXT RES, MARCH 1989

4 Conclusions

4.1 Gum Indalca AGBV thickener, when usedalone, produced a film with continuous structure~hich acted as a barrier to the dye release, resultingm low dye transfer. In this case, only the dye parti-cles at the interface were available for transfer. Thequantity of dye at the interface increased with the in-crease in dye particle size.

4.2 Th~ presence of a suitable auxiliary in the printpaste disrupted the continuity of the thickener filmand enhanced the dye transfer. The dye transfer alsobecame independent of the dye particle size andthickness of wet film deposits.

44

AcknowledgementThe work reported was carried out under the lIT

Delhi-UMIST, Manchester collaborative project o~transfer printing, coordinated by Dr· R.B. Chavanfrom lIT, Delhi and Dr L.W.c. Miles from UMISTManchester. The project received an equipment aidfrom the British Council and research funds fromlIT, Delhi.References1 Hawkyard C J, J Soc Dyers Colour, 97 (1981) 213.2 Detscheva R & Milkova A, Melliand Textilber, 62 (1981) 734.3 Detscheva R, Milkova A & Georgieva A, Melliand Textilber.

62(1981)887. '4 Biedermann W & Isehi A, J Soc Dyers Colour, 99 (1983) 363.5 Chavan R B & Langer M H, Am Dyest Rep, 76(6) (1987) 27.