DEVELOPMENT RESEARCH FOR AN ACRYLIC CONTINUOUS FILAMENT

Abstract

The conditions for modifying a thermo-contractible acrylic continuous filament to stretch yarns by the air-jet false twist method were investigated, and the stretch yarns obtained by the optimum condition as well as the fabrics knitted out of the yarns were compared with those of poly (vinyl chloride) and poly (ethylene terephthalate).The factors taken up in the experiments of the modifying conditions were (A) temperature of the heater, (B) distance between the air-jet nozzle and the hook below it, (C) velocity of winding, (D) pressure of compressed air, (E) rate of overfeeding, and two-factor interactions A×C and D×C. The characteristic properties measured were strength, elongation, rate of fulling, elongation ratio of crimp, elasticity of crimp, and residual twist. An orthogonal divided 313 type experiment gave the following results:1. In principle, when the combination of level of factors gives the larger false twists, the higher values can be obtained on the rate of fulling and on the elongation ratio of crimp of the stretch yarn. It is inevitable, however, that the strength and the elongation of the stretch yarns is deteriorated. On the conditions in which the extreme twists are given, on the contrary, the elongation ratio of crimp becomes lower because of insufficient untwist. In general, less false twist is required for acrylic filaments than that of poly (vinyl chloride).2. Compared with the stretch yarns of poly (vinyl chloride) and poly (ethylene terephthalate), the acrylic stretch yarns have lower strength and elongation, higher rate of decrease in strength, and lower elasticity of crimp. Compared in knitted fabrics, the acrylic ones have the highest value of bulkiness after fulling, though the value becomes lower after scouring because the fabrics are elongated. The compressive elasticity of the acrylic knitted fabrics is about the same as those of poly (vinyl chloride) and poly (ethylene terephthalate), or superior after fulling as well as scouring.3. Worn as an under wear, the acrylic stretch yarns do not give the feeling of power to human body as do those of poly (ethylene terephthalate) that have larger elongation ratio of crimp.