'Starch amide produced from Tamarind Kernel Powder is cooked along with dissolved ammonia in alkaline polyvinyl alcohol solution used in sizing of jute yarns resulting at least 2% increase in weaving efficiency'
An aqueous liquid of polyvinyl alcohol (cold) treated with particular proportions of urea and hydrated sodium acetate to produce acetamide, carbamic acid, carbonic acid and ammonium hydroxide and added in an amount of 13% to 19% by weight with Tamarind Kernel Powder (TKP) which is cooked for sizing of jute yarns show an increase in elongation at break of jute yarns by 4% thus reduces the warp breakage rate by 30% to 40% in power looms as well as in Sulzer looms and weaving shed efficiency is increased by 2% to 4%.
During the formation of fabric by weaving machine (loom) in textile mill, the warp yarns (the set of yarns coming from the beam which is situated at the back of the loom) undergo a lot of stress, strain and abrasion. The reason for stress is the backward and forward pull of the warp yarns and the cause of strain is the mechanical splitting of the warp yarns in order to permit the weft yarn (the single yarn that is traversing across the loom through the splitting of warp yarns in order to interlace the warp yarns). The cause of abrasion is the movements of warp yarns through different fast moving machine parts and also friction with the shuttle.
So, before the warp yarns go to the loom for weaving, they require an external protection. The process of this external protection of warp yarns is called sizing. The main size ingredient used for jute yarn sizing is Tamarind Kernel Powder (TKP), a low cost starch. When a cooked starch paste is formed in addition to other chemicals, water and heat, a viscous paste having adhesive property as well as thin film forming property is generated. This starch paste should have the capability to coat individual yarn and to form thin, smooth and elastic film on the surface of jute yarn.
Jute yarns are mainly sized with cooked aqueous solution of Tamarind Kernel Powder (TKP) along with Carboxy Methyl Cellulose (CMC) or with any sort of cheap natural gums. Chemically the natural gums are for most of the part polysaccharides, but they also have some uronic acid residues. Gums generally used in Indian jute mills are gum Arabic, Senegal, Indian gum or Babul gum. Some Indian jute mills do not use gum at all. However an antiseptic agent is always used with size paste like salicylic acid, salicyl anilide or silica fluoride.
The films of the above size ingredients when dried become hard and brittle. In cotton industries, to decrease brittleness of the starch film lubricants like sulphonated oil, T.R. oil, cottonseed oil or some fatty acids along with softener like tallow, paraffin wax etc. and hygroscopic agents like chlorides of zinc, magnesium, calcium or simply glycerin are used.
About the Author
The author is associated with College of Textile Technology, Hooghly, WB, India.