Synthetic Binder
Water-soluble polymers are applied to warp yarns to increase their abrasion resistance and strength during weaving. This coating, known as polyvinyl alcohol size, forms a tough, flexible film over the individual yarn surfaces. It is used on synthetic blended yarns where natural starches do not adhere well to the fibers.
Application Method
Yarn sheets pass through a heated bath containing the dissolved polymer and are squeezed by heavy rollers. The moisture is removed as the yarn passes over drying cylinders before being wound onto the loom beam. Control of bath concentration and temperature is required to ensure consistent film thickness on the yarn.
Desizing Step
Removal of the protective coating occurs in the finishing mill before dyeing or printing can begin. The fabric is washed in hot water with wetting agents to dissolve and wash away the polymer. This waste stream must be treated because the polymer requires specific biological processes to degrade in wastewater.
If the desizing is incomplete, the remaining residue will block dye absorption and cause light streaks or spots on the finished fabric.
Operational Benefit
Weaving efficiency increases due to the reduction in yarn breaks and dust accumulation on the looms. This binder provides higher yarn protection than traditional starch, which reduces warp shedding on high-speed air-jet looms. This stability allows for faster weaving speeds and lowers the number of machine stoppages.
