STUDIES ON SIZE FOR TEXTILES

Abstract

In order to size effectively to warp yarn with starch at low temperature, starch size solutions with low viscosities were prepared by decomposing starch molecules with α-amylase, and observations are made on the mechanism of addition of starch size to yarn, mechanical properties of starch films and sized yarn, and their relations, with the following results obtained:a) Drop of viscosity of size solution based on decomposition of starch molecules with α-amylase was remarkable, and its dependency on temperature was less in proportion to the degree of decomposition. Viscosity of starch solution illustrated the saturated minimum value after the time of treatment correspond to the addedamount of α-amylase to starch.b) In decomposing starch, it is better to add α-amylase to starch solution after preparing its size solution, for the reason of obtaining homogeneous size solution. Similarly, it is better to treat starch for longer time with smaller volume of enzyme than treatment for shorter time with larger volume.c) Reduction of viscosity by enzyme treatment promotes penetration of size solution into the yarn, and it results in increased amount of size adheres to the yarn.d) Increase of breaking strength and abrasive resistance of sized yarn per unit weight of adhered size is remarkable using the size treated with α-amylase. It may be explained from difference of role between size fixed on surface of yarn which resists mainly to stretch and the inter-fiber size which takes part of cross-links between them.e) As decomposition of starch is advanced mechanical properties of sized yarn gradually deteriorates, but they are much more predominant than in that sized with non-treated starch. All this is due to weakning of mechanical properties of solid phase of fixed size prepared by drying, based on decomposition of starch molecules with α-amylase. It can also be verified by determination of breaking strength and elongation of films made with starch sizes variously decomposed by α-amylase.f) From above results, it is obvious that the analytical method is more desiable to perform extensive study of warp sizing than by determination only of mechanical properties of sized yarn.