Abstract :

This work is an attempt to develop silk / Lyocell blended yarn on short staple spinning system. Defective and Damaged silk skeins were used to blend with Lyocell fibres. The main objective of this work is to develop the technology to process the above blends on existing short staple spinning system. This concept has the techno economical edge over the prevailing the long staple spinning system. The yarns were developed by optimizing parameters in blow room, carding, draw frame, simplex and ring frame. 30s and 60s Ne yarns were developed. The yarns were tested for the tenacity, evenness and imperfections, hairiness properties. The result are highly encouraging. The U% of the yarn is 8 & 10 for 30s and 60s Ne respectively. Number of imperfections per kilometer is less than 30 and 120 for 30s and 60s Ne count respectively.

Introduction :

Silk is one of the oldest traditional textile fibre used for clothing purpose from the time immemorial. Silk fibre is known for its versatile characterstics. Silk fibre dominates all other textile fibres interms of lustre, drapability, elegant look and dyeability. Its functional properties viz. mechanical stability, thermal resistance and hand related properties are in par with other commercially accepted textile fibres.. Even though India is the second largest producer of silk, it is used mainly for ladies ethnic weares and to some extent in upholstery and madeups. Major draw back of silk fibre is its price. Due to high cost of silk fibres its use is restricted to only few fields. Union fabrics are being produced using silk warp and viscose / polyester filament in weft to reduce the cost. Application of union fabrics is restricted to few fields. Acceptance of silk by men is also limited

Silk industry produces 35% reeling waste on the total quantity of raw silk produced which amounts to about 5000 Metric tons of soft waste. Hard waste is generated mainly during twisting and winding etc. (500 tons per annum in India). So far silk hard waste is being used to spin course count yarns to manufacture carpets. Yarn is being spun using long staple spinning system. Carpet yarns produced using short staple spinning system lack commercial value.

In order to make use of waste silk for better applications and to increase its commercial value, authors of this paper have made an effort to produce blended yarn using silk waste. Short staple spinning system (cotton spinning) was used for manufacturing the yarn. New eco friendly regenerated fibre Lyocel-LF was used as the other component. Reason for choosing lyocell was, its properties are more compatible with silk than polyester or viscose Comfort related properties of lyocell is better than regular polyester and it has higher mechanical properties than regular viscose rayon in both in dry and wet condition. 30s and 60s Ne yarns were produced using blend ratio of 50:50. Various spinning parameters were optimised to produce good quality yarn.

Conclusion

From the above results the following conclusions can be drawn Silk can be blended with lyocell fibre and effectively processed on short staple spinning machineries. Carding machine setting has the direct bearing on the properties of the yarn Input and output material quality and quantity in carding has direct bearing on the quality of yarn. Optimisation of roller setting in draw frame, simplex and ringframe improve the evenness and mechanical properties of silk / lyocell blended yarn. Short staple spinning system reduces the number of machinery passages compared to existing spun silk yarn processing. The knitted & woven fabrics exhibits good dimensional stability
The knitted fabrics were exhibiting low angle of spirality The knitted and woven fabrics are exhibiting very good draping properties

Acknowledgement

Management and Principal of BIET, Davangere Management of Lenzing-Austria and Mr.Pradeep Roongta of Stuti Exports, Mumbai
Mr.L.Narasimhan, Vice President and Mr.Rajashekaran, Asst. Manager, LMW, Coimbatore

About the author:

Dr. HL Vijaya kumar completed his Ph.D from Anna University, Chennai . His area of interest is Knitting in particularly Silk & their blends. He has published more than 20 papers in national & international Journals. Undertaken many projects with National & International funding agencies & Industries. He has traveled widely to understand the Sector. He worked with State & central Govt. agencies for the development of textile sector. Organised more than 15 national & state level seminars & symposia�s . Worked in many University bodies as chairman to frame the curriculum for textile & fashion courses. At present guiding 5 students for their doctoral degree. 23 years worked in Engg. Institute as lecturer, Asst Professor, professor & Head of textile department. At present working as principal at Army Institute of Fashion & design , Bangalore. The students projects guided by him bagged many national & state awards. Because of his contribution to the overall growth of the textile industry in India, Indian society for Technical education New Delhi , presented the UP govt. National award during the year 2005.

Address : Army Institute of Fashion & Design,ITI, B Area Sheds,Dooravani Nagar
Old Madras Road ,Bangalore 560016,Karnataka, INDIA

Mobile :09448372421 , Phone: 080- 25617309,25617559
Email: hlvijaykumar@hotmail.com

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2 Materials and Methods

2.1 Meterials

Silk :

Waste silk skeins were procured from local industries and was cut into 38mm length staple fibres using cutting machine. Tenacity and elongation of fibres were 3.5 gpd and 20% respectively. Approximate denier of silk fibres was 0.9. Box 1.0 & 2.0 shows the properties of lyocell and silk fibres.

Lyocell :

Lyocell fibres were procured from lenzing  Austria. Length of the fibre was 38 mm. Tenacity and breaking elongation of fibres was 3.5 gpd and 14% respectively. Approximate denier of fibre was 1.2. The box 3.0 shows the availability of silk raw material to produce spun silk yarn using soft waste. It clearly indicates about 5000 tons of soft silk waste is available in the market

2.2 Methods

Yarn production

Process flow chart is as follows. Two different yarns of nominal count 30s and 60s Ne were produced using sandwich blending. Blend ratio was 50:50.

From the above flow charts it is clear that the silk has to pass through 11 to 12 different operations before the raw material is converted into yarn. The total conversion cost per Kg. of yarn comes to about Rs.350=00. In long staple spinning the appearance of the yarn depends only on doubling and singeing operations. To produce the same yarn on short staple spinning number of machine required is only 6. The total conversion cost comes around Rs.50=00. Because of the reduced hairiness and imperfections, single yarn can be used to develop fabrics of various end use.

Machines particulars used for production of yarn on short staple spinning

The table 2 shows the carding machine setting and also the properties of card sliver. The sliver properties of trial 3 is found to be better compared to trial 1 & 2. The reduction in the density of lap, widening of the front plate setting, reduction in the delivery speed and closure setting of flat to cylinder has the bearing on loading of cylinder and flats, fibre transfer coefficient and also number of fibres in the unit area of cylinder and flats. The hank of the delivered sliver is made little finer in trial 3, in order to minimise the neps/g, compared to trials 1 & 2.

The details of the machine particulars of draw frame, simplex and ring frame are given in table 3, 4 & 5.

Table 6 & 7 shows the yarn properties of Silk / Lyocell blended yarns of 30s & 60s Ne respectively. The trial 3 is exhibiting better yarn properties compared to trial 1 & 2 in terms of evenness, total number of imperfections and hairiness for both the yarns. CV% of count and RKM value are better for the yarn produced with trial 3.

KNITTED FABRIC PARAMETER

The Table-8 shows the knitted fabric properties of silk/Lyocell blended yarns. The most interesting factor is that, with a loop length of 2.5 mm. the fabric has achieved very high stable configuration with a single wash. This can be seen from the value of loop shape factor. The tightness factor used to develop the single jersey fabric is about 17.74. This also exhibit very low angle of spirality. The draping properties of the single jersey and the lacoste are extremely good. Along with the lower drape coefficient, number of nodes generated on the draping instrument is more than 12. This shows the suppleness of the fabric which intern improves the hand value of knitted garments.

The Table -10 shows the properties of woven shirting and suiting fabrics. The same trend can be seen in terms of drape and also bending properties.