GB1216786A - Conjugate spinning of acrylonitrile filaments - Google Patents

Abstract

1,216,786. Conjugate spinning acrylonitrile filaments. ASAHI KASEI KOGYO K.K. 1 April, 1969, No. 17051/62. Heading B5B. [Also in Division D1] In a process for the production of conjugate acrylic filaments, at least two polymer components, each containing at least 50% by weight of acrylonitrile and one component having a higher acrylonitrile content and heat contractibility than the other(s) are spun from nitric acid solution, into a coagulating bath, the filaments are stretched at an elevated temperature, dried in the stretched state, heat treated in the tensionless state at a temperature between 98 and 150‹ C., preferably 110‹ to 140‹ C., and finally stretched at a temperature between 90‹ and 260‹ C. After drying the filaments may be subjected to treatment with hot water, especially at above 60‹ C. Final stretching is suitably effected to a draw ratio of from 1À25 to 3À0 especially 1À35 to 2À5. Both conjugate and sideby-side filaments may be spun, conjugate ratios of 60/40 to 40/60 by weight being preferred. In a typical example a first copolymer composed of 92% by weight of acrylonitrile and 8% by weight of methyl acrylate and a second copolymer composed of 90% by weight of acrylonitrile and 10% by weight of acrylamide are separately dissolved in 67% by weight nitric acid of - 5‹ C. to give a 16% by weight solution. These solutions are fed in equal quantities to the same spinneret to produce a side-by-side conjugate filament. The extruded filament was coagulated in 30% by weight nitric acid, rinsed with water, subjected to a 9-fold stretching in a water bath at 98‹ C. and dried. The filaments so prepared were then crimped by treating with saturated steam at a temperature between 100‹ and 133‹ C. in the tensionless state for 10 minutes. Finally the filaments were heat stretched at temperatures of between 110‹ and 140‹ C. to a draw ratio between 1À15and 1À39. Spinnerets suitable for the spinning of the conjugate filaments are shown in Figs. 1 and 3. In Fig. 1 the solutions of the two components are delivered to the annular spaces 14 and 16 from which they are delivered separately to the chamber 21. The spinning jets are placed so that extrusion occurs at the interface of the spinning solutions. Ternary conjugate fibres (Figs. 6A, 6B and 6C, not reproduced) are produced by the spinneret shown in Fig. 3 which works on the same principle as that described above. A number of variations on the technique and a list of suitable copolymers are given in the Specification.