GB899263A - Improvements in or relating to synthetic fibres for blending with natural fibres - Google Patents

Abstract

Synthetic filaments which are to be stapled and blended with fibres of lower tenacity (see Group IX) are produced by drawing continuous filaments of a linear condensation polymer capable of existing in a highly oriented and highly crystalline state, e.g. polyamides, such as polyhexamethylene adipamide or polycaproamide, or polyesters, to impart a high degree of orientation thereto, and heating the oriented filaments for a time and at a temperature such that the product of the time in seconds and the temperature in degrees Centigrade is 1000-6000 while maintaining them under a tension which allows them to shrink, if at all, by not more than 4% of their length, so that the orientation is retained. Stapled fibres are stated to have a load-bearing capacity of at least 2,1 g. per denier at 7% elongation and not more than 6% shrinkage after boiling, both properties being measured after nine days ageing without tension at 78 DEG F. and 72% relative humidity. In the operation of drawing apparatus, Fig. 1 (not shown), multiple ends of undrawn filaments from a bank of spinning machines or from a creel are combined into a heavy denier, e.g. 63,000, tow, and enter the apparatus as a flat band or ribbon which passes around a series of feed rolls running at the same or different peripheral speeds, thence in a zig-zag path around two or more snubbing pins, over and in contact with an elongated, heated plate, and around a series of draw rolls running at the same or different peripheral speeds in excess of that of the feed rolls. Specifications 543,466, 868,496 and U.S.A. Specifications 2,311,174 and 2,694,447 are referred to.