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COMFORT RICH VISCOSE CREPE FABRICS

Published: June 12, 2017

Author: TEXTILE VALUE CHAIN

Mr. S. K. Hada (A.V.P. TRADC), Ms. Ankita Kaushik (Engineer TRADC), Mr. Deepak Gupta (Engineer TRADC)

Introduction

The word crepe means crinkled or granular surface. This distinctive grainy touch may be achieved by weaving variations by or by applying a chemical or mechanical treatment. Popular crepes include georgette, chiffon, crepe-back satin, crepe de Chine, etc. Polyester is one of the most extensively used fibres in crepe fabrics in the industry because of lightness, bright shade, a good deal of drape and easy to produce variation. However, such product lack in comfort value, being from polyester. It has been tried to develop crepe fabric from regenerated cellulose fibre with an additional value of comfort along with lightness, shade brilliancy and wonderful drape. Major challenges are re-engineering of fabric specification along with re-design of wet processing the meet crepe fabric expectation by consumer.

Types of crepe fabric-

Objective: It is required to do re-engineering of fabric design and re-design wet processing to get crepe effect in 100% viscose woven fabric.

Effect development by creating pattern of SHT & normal yarn in fabric

Viscose Crepe fabric has been developed with Viscose ‘Z’ Super High Twist yarn as warp and incorporating a 2/2 alternate pattern of Viscose ‘S’ and ‘Z’ Super High Twist yarns as weft. Use of viscose super high twist yarns with differential TPI in warp and weft together with alternate ‘S’ and ‘Z’ twisted yarns in weft, utilizes the kinetic energy of yarns in the plain weave fabric. As the cloth is released from the loom, the yarns struggle to unwind within the confined structure, thus giving grainy handle, along with a very comfy handle to the fabric because of the inherent comfort properties of viscose fibre.

The crepe effect has been developed in TRADC by using following:
- Warp: 40s Viscose ‘Z’ SHT with a TPI of 33
- Weft: 40s Viscose ‘S’ SHT + 40s Viscose ‘Z’ SHT in pattern of ‘SS/ZZ’ with a TPI of 38 in each
- Weave: Plain
- R x P: 80 x 76
- GSM: 115

Diamond effect can also be produced by using parameters as given below:
- Warp: 2/30s Viscose in a pattern of ‘SS/Z’ (16 TPI of ‘S’ twist & 19 TPI for ‘Z’ twist yarns respectively)
- Weft: 16s Viscose HT with a TPI of 19
- Weave: Plain
- R x P: 46 x 28

Processing of crepe fabrics

Earlier, the distinctive surface of crepe fabric in wet processing used to be achieved by application of a special finish that causes the fabric to shrink wherever it is applied. The method was first patented in England in 1822, when plain woven, thin silk gauze stiffened with shellac was passed under a heated, engraved copper cylinder to receive embossed patterns. At this time, heavily textured crepes, particularly the printed varieties, were called “crepe.” As a processor, it was a challenge to produce heavy textured crepes.

Viscose crepe fabric developed by using super high twist yarns with differential TPI in warp and weft together with alternate ‘S’ and ‘Z’ twisted yarns in weft, utilizes the kinetic energy of yarns in the plain woven fabric. As per normal route, the fabric was processed in soft flow dyeing machine. But while desizing, selvedges of fabric were torn through entire length as weft yarn with high TPI struggled to unwind within the confined structure. Due to uneven release of tension and poor wet strength of viscose fibre, weft yarns started to break near selvedge.

Next, the fabric was processed in Jigger. But due to high tension on fabric throughout entire length, grainy effect was not achieved. The process was re-engineered and the fabric was processed in soft flow dyeing machine.

This time the fabric was desized in garment dyeing or drumming machine so that both warp and weft yarns would allow untwisting and fabric will shrink up to its limit. The fabric could not be scoured and dyed in garment dyeing machine as there could be chances of uneven dyeing. So the fabric was further processed soft flow dyeing machine as per normal viscose dyeing route. After completion of process, sufficient grainy effect on fabric surface had been achieved. Now the challenge was to dry and finish the fabric because passing the fabric through padding mangle to dry it on stenter, the fabric could flatten, thus vanishing the grainy/crinkle surface seemed to vanish.

So, next time the fabric was dried on relax dryer so that to dry it in tension free state keeping the distinctive surface of crepe. As we don’t have facility of relax dryer so we did exhaust finish in soft flow dyeing machine and then removed excess water through hydro extractor followed by drying in tumble dryer.

Thus, viscose crepe fabric has been developed in TRADC with finished details as below: R x P: 96 x 84 & GSM: 137