ANTI PILLING TREATMENTS
INTRODUCTION The surface appearance of a textile material is very important to the consumer. Pills are an aesthetic and physical nuisance. The pilling of textile materials fabrics refers to an appearance caused by bunches or balls of tangled fibers held to the surface. This unpleasant appearance can seriously compromise the fabrics acceptability for apparel. This paper reviews about new techniques and developments in anti pilling treatments from fibre stage and mechanical and chemical treatments that prevail over pilling problem.
PILLING MECHANISMThe pills are formed only during wear ,wash and tear due to abrasion affecting appearance, touch and handle of fabrics. The mechanism of pilling goes through the following four stages:1. Fuzz formation on fabric surface.2. Entanglement of fibers in the fuzz with each other.3. Densification of these entanglements into small balls called pill.4. Shedding away of pills.
Fuzz formation is result of constant gentle abrasion. In a garment, it is usually observed near the abrasion areas such as near the pocket, collar. etc.
PILLING PERFORMANCE OF SYNTHETIC AND NATURAL FIBRES
Most fabrics exhibit some degree of pilling. Fabrics constructed entirely of natural fibers are “low-pill” because the pills are smaller and fall away before they are noticeable. A woven fabric is, by its very nature, of a tighter construction, so it is more difficult for fibers to migrate to the surface and cause pilling. Synthetic knits exhibit pilling problems because of their loose construction, and knits of synthetic staple fibers contain numerous eligible free fiber ends that begin the pilling process . Filament fabrics have no free ends to migrate, so no pills can form.
The pilling performance of fibres is shown in the graph 1
FACTORS AFFECTING PILLING:
The pilling tendency of fabrics depends on denier of fibres, twist factor of yarn, construction of fabric and processing steps used during the manufacture of fabric as under:1. Denier of fibres: Fine denier fibres tend to pill more as they possess less stiffness. Secondly, fibres per unit length of yarn will be more in a case of fine denier compared to the yarn made from coarser denier so that there will be more fibre ends exposed rendering the fabric more prone to pilling.
2. Twist factor of yarn: The yarn with lower twist factor below 3.4 will pill more than the yarn with higher twist factor. It is therefore necessary to choose slightly higher twist factor for single /doubled yarn if it would not adversely affect the feel of the fabric. The double yarn exhibits less pills.
3. Fabric construction: Closed weave fabric with a high sett, pills less. Plain weave fabric with maximum yarn intersections gives better pill rating. Weaves with longer floats like twills and sateen have less binding points so pill more.
4. Processing: Processing steps involving both mechanical and chemical operations which would render fabric surface clean and hair free play a vital role in minimizing pilling. For effecting control on pilling, precautions will have to be taken from early stages of processing.
Pilling can be prevented or considerably reduced by fiber blends, appropriate yarn fabric construction, suitable finishing or by using low-pilling synthetic fibers.
ANTI PILLING FIBRES
The low-pilling effect in synthetic fibers is obtained by chemical modification or by using low molecular weight spinning raw materials. The use of longer staple fibers in worsted yarns compared to shorter fibers used in cotton spun yarns may also reduce pilling. The finer the fiber the less pilling occurs, as flexing elasticity is reduced. In the case of micro staple fibers the fibers break off. Thus pilling is avoided.
Also the use of trilobal, pentalobal or other kinds of profiled fiber types can reduce pilling. A cross-section of the profiled fibers shows that they are not round likes standard fibers, but shaped with special spinnerets.
Birla Acrylic® has come out with an innovative fibre which reduces pill formation over repeated usage. Birla Acrylic® Anti-Pill fibres reduce pilling in fabrics and subsequently slow down apparel aging. Birla Acrylic® delivers a high pilling grade of 4-4.5 (on a scale of 5) following ICI Pill Box Test. The Anti-Pill fibre has been specifically engineered to have sustainable anti-pilling performance throughout the lifetime of the apparel. Products manufactured out of Birla Acrylic® anti-pill fibers stay new and elegant even after repeated washing cycles. Birla Acrylic® Anti-Pill fibers can be blended with both natural and synthetic fibres like wool, viscose etc. In blends with other fibers, it enhances the pill performance of blends. It is available in a range of denier (1.2 Den to 2.5 Den) and cut-length (38, 44, 51, 64 mm). It is available in both Tow/Fiber and Bright/Semi Dull options.
Trevira 350 is a low-pill polyester fibre for the weaving and knitting sectors. The special characteristics of Trevira 350 are embedded in the chemically modified polymer, which has hydrolysable bonds in the polyester chain. The bonds dissolve during the dyeing process, substantially reducing the transverse strength of the fibre. This reduction in tenacity is intended to lead to any pills that form with wear breaking off. This occurs early in their development.
DuPont now introduces soft, versatile CoolMax Alta™, a new low-pill product for use in 100%constructions. The product combines the processability of CoolMax™ with the consumer value of low-pill and moisture management while maintaining that next-to-the-skin softness. DuPont has modified the chemical arrangement of the polymer at the point of manufacture .CoolMax Alta™ provides pill ratings of 3 or better, (ASTM D3512-82 where 1 is severe pilling and 5 is no pilling), equal to or better than other synthetics and even wool.
FIBRES TYPES WITH ROUND CROSS SECTIONS
NORMAL HOLLOW PILL RESISTANT
SUPE PILL RESISTANT
FIBRE CHARACTERISTICS INITIAL STATEThickness dtex 3.3 3.3 3.3 3.0Maximum tensile loadcN/tex
50 45 40 30-33
Maximum tensile load extension%
35 40 45 32-37
Relative loop resistance %
95 90 90 80
Blending resistance(turns)
150,000 150,000 50,000 900-1,300
After 4 hours of high-temperature dyeingThickness dtex 3.6 3.6 3.6 3.0Maximum tensile 45 40 35 22
loadcN/texMaximum tensile load extension%
35 40 40 25
Relative loop resistance %
85 80 80 70
Blending resistance(turns)
70,000 120,000 20,000 1,000
This table clearly shows that mechanical and technological properties of fibres can be altered by modifying the cross sectional shape and by adding copolymers (super pilling resistant).It is important to reduce flexing resistance so as to decrease pilling.
When pills are about to be formed, the fibres that have been pushed or pulled out should preferably break off, a circumstance which depends on maximum tensile load and elongation behaviour.-Evidence gained from experience shows that in the finished product, super pilling fibres should have a thickness/maximum tensile load of 30 cN/tex as well as a maximum load extension of 35%.Fig illustrates the effects that can actually be achieved in similarly constructed plain woven materials made exclusively of one type of fibre.
The curves of the graph show that pills are formed when fabric is exposed to abrasion, which is also the case for wool. The number of pills developed per unit area, however varies considerably depending on the type of fibre. If abrasion continues after the maximum number of pills per unit area has been reached, pills break off. Therefore total number of pills will decrease, despite the formation of new ones.If normal polyester fibres are used, still many pills will remain visible on the fabric, whereas in the other three types of fibre,pills will break off almost entirely or even entirely.
Chemistry of anti-pilling finishes
For all kinds of finishes, special product groups are known and listed in catalogues. There is, however, no group of anti-pilling products in the International Textile Auxiliaries Buyers' Guide. The reason is not that this finish is not important enough. This astonishing fact may be explained by:
the large variety of parameters that influence the pilling behaviour, the corresponding variety of approaches to anti-pilling finishes, the circumstance that textile auxiliary producers mostly recommend products that are primarily used for other purposes for anti-pilling finishes, there are only a few general recipes for anti-pilling finishes, the need for specific solutions for every type of article, including all other
finishing components
PHYSICAL PROCESSES FOR REDUCING PILLINGShearing or cropping
Cropping and shearing reduce pilling by reducing the length of the projecting fibres. Cropping and shearing give a much superior handle to singeing.
Singeing
Singeing with shearing / cropping and optimum heat setting would reduce pilling. The parameters during singeing will have to be optimized with respect to speed, quality of flame and number of passages to obtain the fabric with the desired level of pilling resistance
BrushingIn the case of tighter-woven fabric made from highly twisted yarn, loose fibres can be
brought to the surface of fabric by means of brushing, where they can be removed by a close shearing. Such a procedure is not possible on loosely spun yarns with a fluffy surface.
ThermosettingHeat-setting tends to produce smooth fabric laying down the individual surface fibres to the fabric body and polyester fibres are rendered slightly stiffer so that even at a later stage tend to entangle less.
Special treatments
_ Sanding of the fabrics before brushing and shearing_ Wet milling with soap for three hours, followed by brushing and shearing
_ Heat treatment on an enclosed tenter frame at 204°C
_Hot-impregnation treatments applicable to synthetic fibres
Steaming: steaming at temperatures above 100°C (generally 120°C or 130°C) also reduces the pilling tendency as a result of increasing the coefficient of friction (i) Treatment in soapy water
High-pressure heat treatment with liquid impregnationCareful selection of patterns and weaves
ELECTRIC PILLER/FABRIC SHAVER
Fabric shavers are easy for removing pills on a flat knit, but they should not be used on knits with naps, textures or lofty surfaces.
KNIT PICKER
For any snags or loose ends of yarn, can be removed with a "knit picker". These are hook-like tools with an eye that draws the yarn from the outside of the garment to the inside
MillingIt is the process of shrinking the fabric to the required degree, thickening it, and giving it the desired appearance and handle. The milling machines are of two types : stock and rotary. The rotary types are widely used.
Thermal shockRandom flattening of fibres (synthetic)Ultrasonic treatment
2. Chemical processes for reducing pilling(a) Treatments based on silicic acid(b) Latex treatment(c) Easy-care finishes(d) Special treatments(e) Shrink-resist treatmentsf) Treatments based on thermoplastic vinyl resin(g) Treatments for blankets and melton fabrics(h) Treatments for carpets and nonwoven fabrics(i) Chemical treatments applicable to acrylic fibres(J) Chemical treaments applicable to polyester fibres
Special equipments
SanforisingSanforising resulted in a decrease in pilling rating. However, the effect on pilling was not too bad when a combination of Softicone NWS (a blend of nonionic water-dispersible esters)and Eccosoft 2010 (a compounded cationic fatty amide softener) was applied before the sanforising treatment. There are two possible explanations for the decrease in pilling performance ofthe fabric after sanforising. Firstly, during sanforising,friction between the rubber blanket and the steel drum, which forces the fabric yarns to come closer, possibly causes some weakening of the fabric surface fibres.Secondly, after fabric shrinkage as a result of sanforising,the number of yarns and fibres per unit area increase, resulting in an increased chance of the formation andpresence of pills per unit area of the fabric, leading to a poor pilling rating.Chemical finishes:
Different chemical finishing approaches have been made to prevent pill from accumulating on fabric surface which include the following:
Application of polymers by padding and coating techniques.
Reduction in the strength of fibre to reduce pilling to cause the pills to fall off from the material as soon as they get formed and
Application of enzymes (bio finish) to 100% cotton textiles to cause removal of loose fibres in the yarn to reduce pilling tendency.
The polymeric formulations bring about the binding of the loose fibres into the fabric. The products normally used in this type of finish are friction reducing lubricants to minimize damage due to abrasion. The acrylic co-polymers which can be modified to suit the requirements are normally used.
Examples of few areThe amine treatment may be combined with other textile finishing operations,
such as dyeing. It is performed on conventional treating equipment without inhalation hazard since the treating chemical has a low volatility. Furthermore, the treatment of the textile may be performed as a continuous operation where a relatively short chemical contact time is a necessity since only small concentrations of the chemical are required for short periods of time-Polyester fabric
Softeners, which decrease fibre-tofibrefriction by internal lubrication, such as nonionicorgano-modified silicone microemulsions and aminofunctional polysiloxanes, result in a decrease in fabric pilling performance. Furthermore, as far as polyester ⁄viscose blended fabrics are concerned, sanforising treatment also results in an increase in pilling propensity
The Siroflash anti-pilling treatment for knitted fabrics is a process involving exposure of the fabric or garment surface to short wavelength ultraviolet radiation (UVC), fol lowed by a mild wet oxidation treatment using, for example, hydrogen peroxide or salts of permonosulphuric acid. UVC exposure is confined to the surface fibers and presensitizes them to the wet oxidation process, which selectively weakens them relative to the bulk fibers responsible for fabric strength. Because the surface fibers are much weaker after treatment, no anchor fibers are available to secure pills to the fabric surface. The treatment is a highly effective, chlorine-free method of preventing pilling in wool knitwear
In the second approach, polymer structures of synthetic fibres are altered to give fibres of lower tenacity. The fabric from the yarns spun from fibres of lower strength show significant improvement in pill rating as compared to the fabric made from the normal polyester fibre.
In the third approach, bio polishing with cellulase enzvme is carried on 100% cellulosic or cellulose rich blend fabrics to eliminate loose fibres which results in clean and smoot,h surface with improved pill rating.
The bio-polishing process targets the removal of the small fiber ends protruding from the yarnsurface and thereby reduces the hairiness or fuzz of the fabrics. The hydrolysis action of the enzymeweakens the protruding fibers to the extent that a small physical abrasion force is sufficient to breakand remove them. Bio polishing can be accomplished at any time during wet processing but is most
convenient performed after bleaching.It can be done in both continuous or batch processes. However, continuous processesrequire some incubation time for enzymatic degradation to take place. Removing the fuzz makes thecolor brighter, the fabric texture more obvious, and reduces pilling. Unfortunately, the treatment alsoreduces the fabric strength. Smoother yarns also increase the fabric softness, appearance and feel.Since it is an additional process, the bio-polished garments may cost slightly more. Next time you buyapparel, look for the label "Bio-Polished."
1.2 Denim
BRIEF REVIEW OF RESARCHERS WORKGintis and Mead (4) have determined the fuzz formation tendency of
different fibers which is given in table(1) It will be seen that fibers have the lowest tenacity like wool and acetate have the lowest tendency to form fuzz.
However, viscose with low tenacity has a higher tendency to fuzz compared to Dacron that is 50% stronger.Thus, why cannot explain the magnitude of fuzz formation simply with reference to the tenacity of fibers (15).There are other factors involved.
Also, they reported the low inter-fiber friction as well as fiber stiffness in terms of fiber modulus facilitates migration of fibers out of fabric surface. Wool- has the lowest inter- fiber friction and moderate stiffness; its low tenacity causes the fuzz formation. As results of surface friction, several fibers are fractured and are able to easily migrate out of the fabric and get entangled in the pill.
Research work carried out by Richards,Sharma clearly indicate that as yarn becomes finer, pilling increased when all other yarn and fabric parameters were kept constant. There is complete agreement that increasing the twist factor of yarn decreases the pilling tendency as fibers find it difficult to easily migrate out.
Several workers have confirmed that the higher yarns twist whether in singles or in double yarns the lesser is the pilling.
Work carried out by kullman and Rupenicker indicate that fabric woven from worsted spun yarns pill less than those from cotton spun yarns. Viscose gives more pilling than wool does when blended with polyester.
Sivakumar and Pillay investigated the structure of pills and nature of fibers that go into pill in different types of fabrics were examined microscopically and the influence of fiber and yarn parameters was analyzed.
Kulkarni suggested the use of higher cover factors for weaves other than plain weave structure to decrease the pilling tendency. He determined that warp and weft English cover factors from 12 to 14 are adequate for plain structure, and for twill and dobby structures he suggested cover factors from 15 to 18.
Wemyss observed that finishing processes playa very important role than various factors responsible for pilling resistance. Poor finishing leads to pilling even in a well design fabrics. The main role of finishing is tostabilize the fibers inside the yarn and to remove the surface nap. This is done by heat setting, singeing and brushing /cropping.
ANTIPILL FIBRES
Birla Acrylic® has come out with an innovative fibre which reduces pill formation over repeated usage. Birla Acrylic® Anti-Pill fibres reduce pilling in fabrics and subsequently slow down apparel aging. Birla Acrylic® delivers a high pilling grade of 4-4.5 (on a scale of 5) following ICI Pill Box Test. The Anti-Pill fibre has been specifically engineered to have sustainable anti-pilling performance throughout the lifetime of the apparel.
Birla Acrylic® Anti-Pill fibers can be blended with both natural and synthetic fibres like wool, viscose etc. In blends with other fibers, it enhances the pill performance of blends and adds a differing value for every occasion. Fabrics made out of Birla Acrylic® Anti Pill fibers provide a silky soft feel to the skin. It is lighter in weight as compared to other natural or synthetic fibres like cotton, polyester, silk etc. and provides excellent wearer comfort. Birla Acrylic® Anti-Pill fibre is available in a range of denier (1.2 Den to 2.5 Den) and cut-length (38, 44, 51, 64 mm). It is available in both Tow/Fiber and Bright/Semi Dull options.
References
1. Colourage, September 2008 by Rakesh Goyal, C. N. Prabhu2. http://www.vintagevixen.com/articlesCare/pilling.asp 3. Effect of different softeners and sanforising treatment on pilling
performance ofpolyester⁄viscose blended fabrics Tanveer Hussain,a,* Sohail Ahmedb and Abdul Qayum
4. Using Ultraviolet Radiation to Reduce Pilling of Knitted Wool and CottonKeith Millington
5. Colourage, September 2008 by Rakesh Goyal, C. N. Prabhu6. Chemical Finishing of Textilesby W. D. Schindlerand P. J. Hauser7. Birla Acrylic® Anti-Pill Fibers at Spin Expo Shanghai 20108. Pilling resistance of blended polyester / wool fabrics-BY: M
H.ELSHAKANKERY
Mechanical and technological properties of fibres can be altered by modifying the cross-sectional shape and by adding copolymers(super pilling resistant).It is important to reduce flexing resistance so as to decrease pilling.
When Pills are about to be formed,the fibres that have been pushed or pulled out should preferably break off, a circumstance which depends on maximum tensile load and elongation behaviour.Evidence gained fro experience shows that in the finished product,super pilling fibres should have a thickness/maximum tensile load ratio of 30cN/tex as well as a maximum load extension of 35%.Fig 1- 29 illustrates the effects that canactually be achieved in similarly constructed plain woven materials made exclusively of one type of fabric.
The curves of the graph show that pills are formed when fabric is exposed to abrasion,which is also the case for wool.The number of pills developed per unit area,however,varies considerably depending on the type of fibre.If abrasion continues after the maximum number no of pills will decrease,despite the formation of new ones.If normal polyester fibres are used,still many pills will remain visible on the fabric,wheras in the other three types of fibre,pills will break off almost entirely or even entirely.
Characterization of Plasma-coated Wool Fabrics
1. Raffaella Mossotti 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy
1. Guiseppina Lopardo 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy
1. Riccardo Innocenti 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy
1. Giorgio Mazzuchetti 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy
1. Fabio Rombaldoni 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy
1. Alessio Montarsolo 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy, [email protected]
1. Espedito Vassallo 1. C.N.R. National Research Council, IFP-Institute of Plasma
Physics, via R. Cozzi 53, 20125 Milan, ItalyAbstract(Si : Ox : Cy : Hz) thin films were deposited on knitted wool fabrics by plasma-enhanced chemical-vapor deposition using hexamethyldisiloxane as a monomer and argon and oxygen as feed gases in low-pressure equipment. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses confirmed the presence of the siloxane coating. The pilling tendency of treated samples was investigated for different deposition powers, ranging from 30 to 50 W. A reduction on pill formation was observed for all treated samples. A silicone-based wet chemical treatment was
taken as the reference method for pilling reduction and plasma treatments were compared with it. The pilling grade of treated fabrics was also tested after washing and the results confirmed a good pilling behavior of plasma-treated fabrics. Changes were observed in the bursting resistance of plasma-treated wool samples compared with untreated ones, while no significant differences were found in the whiteness index.
hexamethyldisiloxane
pilling
plasma-enhanced chemical-vapor deposition
Characterization of Plasma-coated Wool Fabrics
1. Raffaella Mossotti 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy
1. Guiseppina Lopardo 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy
1. Riccardo Innocenti 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy
1. Giorgio Mazzuchetti 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy
1. Fabio Rombaldoni 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy
1. Alessio Montarsolo 1. C.N.R. National Research Council, ISMAC-Institute for
Macromolecular Studies, Corso G. Pella 16, 13900 Biella, Italy, [email protected]
1. Espedito Vassallo 1. C.N.R. National Research Council, IFP-Institute of Plasma
Physics, via R. Cozzi 53, 20125 Milan, ItalyAbstract
(Si : Ox : Cy : Hz) thin films were deposited on knitted wool fabrics by plasma-enhanced chemical-vapor deposition using hexamethyldisiloxane as a monomer and argon and oxygen as feed gases in low-pressure equipment. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses confirmed the presence of the siloxane coating. The pilling tendency of treated samples was investigated for different deposition powers, ranging from 30 to 50 W. A reduction on pill formation was observed for all treated samples. A silicone-based wet chemical treatment was taken as the reference method for pilling reduction and plasma treatments were compared with it. The pilling grade of treated fabrics was also tested after washing and the results confirmed a good pilling behavior of plasma-treated fabrics. Changes were observed in the bursting resistance of plasma-treated wool samples compared with untreated ones, while no significant differences were found in the whiteness index.
hexamethyldisiloxane
pilling
plasma-enhanced chemical-vapor deposition
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