Influence of core yarn properties on pile loss in chenille plain knitted fabrics

Transcription

1 Indian Journal of Fibre & Textile Research Vol. 32, December 2007, pp Influence of core yarn properties on pile loss in chenille plain knitted fabrics Banu Uygun Nergis a Textile Engineering Department, Faculty of Textile Technology and Design, Istanbul Technical University, Istanbul, Turkey Received 16 October 2006; revised received and accepted 26 March 2007 The effect of core yarn properties, such as core yarns material type, yarn count, structure, twist and twist direction. On pile loss tendency of chenille yarns in plain knitted fabrics has been studied. It is observed that the chenilles produced with coarser yarns result in lower amount of pile loss after abrasion than that produced with fine count components. Viscose fibres are not suitable materials for chenille yarns when their effect on pile loss tendency is considered. The use of core yarns having the same twist direction as the chenille yarn increases the abrasion resistance of fabrics, while it causes spirality problem. It is also found that the use of higher twist in core yarns is not a remedy for the pile loss problem in chenille yarns. Keywords: Acrylic, Chenille yarn, Cotton, Core yarn, Knitted fabric, Pile loss, Viscose IPC Code: Int. Cl. 8 D03D27/18 1 Introduction Fancy yarn is made with a distinctive profile or a construction that differs from basic single and folded yarns, the objective of which is to enhance the aesthetics of the end product with respect to visual and textural properties. 1 Chenille yarn, which is a kind of fancy yarn, consists of short lengths of spun yarn or filaments that are held together by two ends of highly twisted fine strong yarn. The short lengths are called the pile and the highly twisted yarns are called the core. 2,3 Many studies have been conducted on the problem of pile loss in chenille yarns. These are mainly on the effects of pile yarn properties, pile length and density, and chenille yarn twist on pile loss of knitted and woven fabrics However, there is no study available on the effects of core yarn properties which hold the pile yarns in the body of the chenille yarn. In this work, the influence of core yarn structure, such as yarn type, fibre type, twist direction and twist amount, and pile yarn structure, such as fibre type and the yarn type, on the performance of chenille yarn knitted fabrics has been studied, mainly in terms of pile loss which is the primary concern for the chenilles. 2 Materials and Methods 2.1 Materials The whole study was divided into two parts. In the first part, the influence of fibre type and spinning a uygunf@itu.edu.tr principle employed in the production of core yarns on abrasion behaviour of knitted fabrics made from chenille yarns was studied. The second part was focused on the study of the effect of twist amount and twist direction of the core yarns on abrasion behaviour of fabrics knitted from chenille yarns. For the first part of the study, 250 tex (Nm 4) chenille yarns were produced by using 25 tex (Ne 24/1) combed yarn, 25 tex (Ne 24/1) rotor yarn, 20 tex (Ne 30/1) combed yarn, 20 tex (Ne 30/1) rotor yarn, 25 tex (Ne 24/1) viscose yarn and 25 tex (Ne 24/1) acrylic yarn as core yarns and 25 tex (Ne 24/1) rotor yarn, 20 tex (Ne 30/1) rotor yarn and 25 tex (Ne 24/1) viscose rotor yarn as pile yarns. For the second part of the study, the influence of twist amount and twist direction of the core yarns on pile loss tendeny was studied. For this reason, S- twisted 250 tex chenille yarns were produced having two S-twisted core yarns, two Z-twisted core yarns, and one S- and one Z-twisted core yarn. The twist factors of the core yarns used were α tex 33, 35 and 37. The core yarns used were 20 tex combed yarn and pile yarns were 20 tex rotor-spun yarn. 2.2 Methods The chenille yarns used in the first part of the study were produced at a speed of 6.3 m/min on a Mispa RB-104 model machine. The pile length of the chenille yarns was 0.9 mm. The twist factor of the core yarns was α tex The chenille yarns were first dyed and than knitted on a Shima Seiki SES234-S

2 NERGIS: INFLUENCE OF CORE YARN PROPERTIES ON PILE LOSS IN CHENILLE PLAIN KNITTED FABRICS 435 model flat knitting machine. The chenille yarns prepared for the second part of the study were also produced on a Mispa RB-104 model machine. They were first dyed and then knitted on a Shima Seiki SES234-S model flat knitting machine. The reason for employing rotor yarns as the pile yarns in the chenilles is based on an earlier finding 4 which suggests that the use of OE-rotor yarns as pile yarns has a decreasing effect on pile loss against abrasion. The fabrics were subjected to areal density, fabric thickness, spirality, and abrasion resistance tests according to the standards ISO 3801, BS 2544, ISO 6330, and BS 5690 respectively. For the determination of the abrasion resistance of the fabrics, the weight loss () of the samples was calculated at the end of 3000 rubs. Before starting the abrasion tests, primary trials were made in order to determine the abrasion cycle at which the test would be ended. At the end of 3000 rubs, the abrasion cycle was ended as most of the piles left the surface of the fabrics and they started to attain a worn-out look. The abrasion tests were adopted 4 times for each fabric sample. SPSS 14.0 software for windows was used for statistical analysis of the results and the mean values were compared at a 5 significance level. 3 Results and Discussion 3.1 Effects of Material Type, Core and Core Structure Coding of the chenille yarns produced for the first part of the study and the properties of the yarns Table 1 Coding of chenille yarns/fabrics produced for the first part of the study Chenille yarn/fabric code 25OEc/OEc 20OEc/OEc 25Cc/OEc 20Cc/OEc 25V/OEv 25V/OEc Explanation Core yarns: 25 tex rotor-spun yarn Pile yarn: 25 tex rotor-spun yarn Core yarns: 20 tex rotor-spun yarn Pile yarn: 20 tex rotor-spun yarn Core yarns: 25 tex combed yarn Pile yarn: 25 tex rotor-spun yarn Core yarns: 20 tex combed yarn Pile yarn: 20 tex rotor-spun yarn Core yarns: 25 tex ring-spun viscose yarn Pile yarn: 25 tex rotor-spun viscose yarn Core yarns: 25 tex ring-spun viscose yarn Pile yarn: 25 tex rotor-spun yarn 25 Ac/OEc Core yarns: 25 tex ring-spun acrylic yarn Pile yarn: Ne 25 tex rotor-spun yarn employed in these chenille yarns are given in Tables 1 and 2 respectively. The results of the measurements regarding the first part of the study are given in Tables 3 & 4 and Fig. 1. It is observed that the core yarn material type, core yarn count and core yarn structure influence the abrasion properties of the knitted fabrics made from chenille yarns. A study on the influence of core yarn material on pile loss tendency shows that when the component yarn (core and pile yarn) counts are 25 tex, employing viscose fibre in the core yarn and rotor-spun pile yarn results in an increase in the pile loss of fabrics. Employing viscose fibre both in the core and the pile yarn dramatically increases the pile loss of fabrics. Besides, using acrylic fibres in the core gives the best results in terms of abrasion resistance. Ulku and Ortlek 12 found that the acrylic chenille yarns (having acrylic core and pile yarns) have better abrasion resistance than viscose chenille yarns, while abrasion resistance of chenille yarns is higher than that of viscose and acrylic chenille yarns. The results show that the locking Table 2 Structure of core and pile yarns employed in the chenille yarns for the first part of the study 25 tex rotorspun 20 tex rotorspun 25 tex combed 20 tex combed 25 tex ringspun viscose 25 tex ringspun acrylic count, tex factor α e Hairiness (H) Table 3 Structure of chenille yarns produced for the first part of the study code count (actual) tex Chenille yarn twist twists/m 25OEc/OEc Cc/OEc OEc/OEc Cc/OEc V/OEv V/OEc Ac/OEc

3 436 INDIAN J. FIBRE TEXT. RES., DECEMBER 2007 Table 4 Structure of the chenille fabrics produced for the first part of the study Fabric code Wales/10 cm Courses/10 cm Stitch density stitches/ cm 2 Weight g/m 2 Thickness mm Abrasion 25OEc/OEc 23, Cc/OEc OEc/OEc Cc/OEc V/OEv V/OEc Ac/OEc Fig. 1 Pile loss of chenille fabrics having different core yarn counts and materials performance of acrylic core yarns is more effective on piles than the core yarns. These findings could be related with the differences in surface characteristics of the fibres studied. It is also observed that using finer yarns as core and pile yarns results in a decrease in the abrasion resistance of fabrics, i.e. pile loss increases. The average weight loss values of fabrics made from 20 tex and 25 tex yarns differ from each other statistically. It is known that the hairiness decreases with the decrease in yarn count. This difference can be attributed to the presence of more fibre ends per unit length in coarse yarns. 13,14 As can be seen from Table 2, the hairiness measurements of 20 tex yarns is lower than that of 25 tex yarns which possess more number of hairs in the unit length. More number of hairs protruding from the body of the core yarn might be acting somehow as a barrier for the pile yarns and delaying their removal. Another reason for this result might be due to the locking capacity of the core yarns. As the final count of the chenille yarns is the same, in the chenilles where 20 tex core and pile yarns are used, the pile density is higher. This means that for the chenille yarns from 20 tex core and pile yarns, the core yarns might not have been able to hold the piles firmly. Moreover, the increase in the pile loss of fabrics having rotor core yarns is found to be much more than Table 5 Properties of chenille yarns for the second part of the study /fabric code a count (actual), tex twist twists/m 33 Z-Z Z-Z Z-Z S-S S-S S-S S-Z S-Z S-Z a The number indicates the twist factor while letter indicates twist direction. that of the fabrics having combed ring yarn when the component yarns count is changed from 25 tex to 20 tex. It should be noted that this result is obtained although the chenille yarn having 20 tex rotor core yarn has the highest twist. In finer rotor yarns, it is expected from the belly-bands to form more number of wrapping turns than that present in the coarse rotor yarns. It might have been easier for the piles to move over the wrappings in fine count yarns. For the chenilles in which 25 tex core and pile yarns are used, there is no statistically significant difference between the abrasion resistance of fabrics having open-end rotor core and combed core yarn. However, for the chenilles having 20 tex components, the difference is significant statistically at 5 level of significance and chenilles having combed ring core yarn perform better abrasion resistance. This might also be attributed to higher hairiness of ring-spun yarns as these are more hairy than the rotor-spun ones (Table 2) However, it is impossible to explain the opposite tendency in the case of chenilles having 25 tex components. 3.2 Effects of Core Amount and Direction Coding and the properties of chenille yarns produced for the second part of the study are given in Table 5. In the yarn code, the number indicates the

4 NERGIS: INFLUENCE OF CORE YARN PROPERTIES ON PILE LOSS IN CHENILLE PLAIN KNITTED FABRICS 437 Table 6 Properties of chenille fabrics produced for the second part of the study Fabric code Wales/10 cm Courses/10 cm Stitch density stitches/cm 2 Weight g/m 2 Thickness mm Abrasion Spirality 33 Z-Z Z-Z Z-Z S-S S-S S-S S-Z S-Z S-Z Fig. 2 Pile loss of chenille fabrics having different core yarn twists and directions twist factor and the letters indicate the twist direction of each core yarn. The results of the measurements regarding the second part of the study are given in Table 6. It is observed that irrespective of the twist direction of core yarns, the core yarn twist amount affects the abrasion property and the pile loss tends to increase as the twist amount increases. This could be considered advantegous in terms of chenille yarn production costs as chenille producer has to pay more for high twisted yarns. The twist direction of the core yarns also influences the pile loss amount of the fabrics made from chenille yarns. The difference between the average weight loss of fabrics having core yarns with different twist directions is statistically significant. The influence of twist direction is shown in Fig. 2. S-S coded fabrics weight loss is the lowest while Z-S coded fabrics weight loss is the highest. As the twist of the chenille yarn is in the same direction of S twisted core yarns, the twist amount in each core yarn might have increased. Also, the higher stitch density, weight and thickness of S-S coded fabrics might be considered as an indication of an increase in the snarling tendency of the yarns due to the twist liveliness. These two factors might have enhanced the locking capacity of the core yarns, while discussed factors together with slightly higher chenille yarn twist of S-S coded yarns result in higher degree of spirality in these fabrics. Poor abrasion resistance of Z-S coded yarns could be due to the following reasons. While chenille yarn is being twisted, it is expected that the S coded core yarn twist would increase and Z coded core yarn twist would decrease. The twist increase in S coded yarns might have caused snarling in the yarns due to the twist liveliness and twist decrease in Z coded yarns might have resulted in parallelization of fibres to some extent, thus a smoother yarn surface. Related with this, the gaps between S and Z coded core yarns might have formed, that causes easy removal of the pile yarn fibres. Although locking of Z-Z twisted core yarns is not as effective as S-S twisted ones due to similar fibre configuration in core yarns after chenille twisting, the gaps between each yarn might not have formed, which explains better abrasion resistance of Z-Z coded fabrics than that of Z-S twisted ones. 4 Conclusions In case of chenille yarns, the use of coarser core and pile components (25 tex yarns), instead of 20 tex ones, improves the abrasion resistance of plain knitted fabrics. At this yarn count, the use of rotor core yarn would be more economical for chenille production. It is also inferred from the results that the viscose fibre is not a suitable material for the production of chenille yarns. On the other hand, using acrylic core yarns causes a decrease in the pile loss tendency. However, further studies on all acrylic chenille yarns need to be conducted as dyeing of acrylic/ yarns would be difficult and cause problems unless special colour effects are needed. The increase in core yarn twist decreases the abrasion resistance of the plain knitted fabrics made from chenille yarns. Core yarn twist direction is found to be an important parameter that influences the pile loss tendency of chenille fabrics. Although the

5 438 INDIAN J. FIBRE TEXT. RES., DECEMBER 2007 opposite core and chenille yarn twist directions effect on pile loss is not as strong as that twisted in the same direction, these fabrics give acceptable spirality values. Hence, the use of core yarn twist in the opposite direction as in the chenile yarn could be suggested. Acknowledgement The author is thankful to the BAP-Scientific Research Projects Unit of Istanbul Technical University for sponsoring this part of project on Optimization of chenille structure in order to minimize pile loss and standardizing the numbering system of chenille yarns final count (registration number ). References 1 Lawrence C A, Fundamentals of Spun Technology (CRC Press, Boca Raton, Florida), 2003, Gong R H & Wright R M, Fancy s, Their Manufacture and Application (Woodhead Publishing Ltd., Cambridge, England ), 2002, Çeven E K, Özdemir Ö, Proceedings, IInd International Istanbul Textile Congress (İstanbul Technical University), 2004, Özdemir Ö & Çeven E K, Text Res J, 74 (6) (2004) Özdemir Ö & Çeven E K, Text Res J, 75 (3) (2005) Özdemir Ö & Kalaoğlu F, Proceedings, TECNITEX 2001, Autex Conference (University of Minho, Portugal), 2001, Kalaoğlu F & Demir E, Text Asia, March (2001) Ülkü S, Örtlek H G & Ömeroğlu S, Fibres Text East Eur, 11(3) (2003) Ulcay Y & Eren S, II Proceedings, IInd International Istanbul Textile Congress (İstanbul Technical University), 2004, Hezari M, Yazdanshenas M I & Rashidi A S, Proceedings, 5 th International İstanbul Textile Conference (Marmara University), Ortlek H G & Ülkü Ş, Indian J Fibre Text Res, 29 (3) (2004) Barella A &.Manich A M, Text Prog, Vol. 26, Issue 4 (The Textile Institute, U K), Barella A &.Manich A M, J Text Inst, 79 (2) (1988) Pillay K P R, Viswanathan N & Parthasarathy M S, Text Res J, May (1975) Candan C, Nergis U B & İridag Y, Text Res J, 70 (2) (2000) 177.