GB1155120A - Process for producing Yarn by Fibrillating Film Strips - Google Patents

Abstract

1,155,120. Producing yarns by film fibrillation. CIGARETTE COMPONENTS Ltd. 7 Dec., 1967 [17 Dec., 1966], No. 56579/66. Heading B5B. Yarn is produced from a narrow elongate film strip of synthetic organic thermoplastic material having a cross-sectional area which is appropriate to the desired denier of the yarn, the film strip having been oriented longitudinally by stretching it to strengthen it in the longitudinal direction and weaken it in the transverse direction. Alternatively the film strip may have been slit from a supply reel of film which has been so stretched. The stretched film strip is then passed through a rotative or a non-rotative false twist inducing member without passing around any member extending across the passage of the yarn therein, so that the film strip is caused to split along lines parallel with the longitudinal direction. The false twisting may be carried out first in one sense and then in the opposite sense. After false twisting the yarn may be given a true twist. The film strips may consist of a stereoregular polypropylene or a copolymer of styrene and propylene. The film strips may be stretched in air at an elevated temperature, preferably between 140‹ and 100‹ C., and the stretch ratio used may be between 7: 1 and 13: 1. After stretching, the film may be heat-set at a lower temperature in a relaxed condition. In an example, a polypropylene film 277 mm. wide and 0À046 mm. thick is slit longitudinally into strips 7 mm. wide, stretched at a stretch ratio of 9:1 at a temperature of 150‹ C., passed under minimal tension into an oven at 120‹ C. at a speed of 100 meters/minute and the stretched film strips which now have a thickness of 0À015 mm. are wound up on centre cores. These are placed in an oven at 135‹ C. for two hours, thereafter brought to a woollen yarn ring spinning frame, and the film strips are withdrawn from the centre cores at 20 metres/minute and passed through two counter rotating false twist tubes revolving at 2200 r.p.m. The yarns thereby formed are wound on to ring spindles and twisted. The false and true twisting treatments of the longitudinally oriented film strips may be effected upon a condenser yarn ring spinning frame, for example, a woollen yarn ring spinning frame.