GB1357992A - Yarn product and process - Google Patents

Abstract

1357992 Spinning yarns E I DU PONT DE NEMOURS & CO 23 Feb 1972 [23 Feb 1971] 8394/72 Headings D1F and D1W A fasciated yarn comprises a core of discontinuous organic fibres bound together by discontinuous organic fibres disposed as an irregular helical wrapping therearound and exhibiting a shrinkage differential of at least 5% and a standard deviation in short-term shrinkage variability of at least 2.8. The yarn is prepared by forming e.g. by successive doubling and drafting, a strand of blended organic fibres of which a minor proportion e.g. 1-40% by weight, are relatively high shrinkage fibres, drafting the strand to form a flat untwisted bundle, removing this from the front draft rollers by an aspirating fluid jet and false-twisting it e.g. within a torque jet, into a yarn. The yarn is incorporated into a fabric which may be subjected to shrinkage treatment to produce crepe effects therein resulting from differential shrinkage of the yarn fibres: alternatively, the fabric may be finished flat, heat-set and hot-calendered to produce a smooth fabric. Suitable high and low shrinkage fibres, which may be of similar or different polymeric composition, include polyamides, polyesters, polyacrylics, cotton, wool and bicomponent, mixed polymer and/or blended forms thereof and may vary in length: the yarn may incorporate one or more continuous filaments. According to a described test, yarn shrinkage differential is the difference between calculated percentage shrinkages based on length measurements of a sample skin under light, and then heavy, load before and after relaxation under no load, and is effective to detect the presence of relatively high shrinkage fibres in the yarn and provide indication of the concentration thereof. In a shrinkage variance test, standard deviation of a yarn is calculated from measurements of straightened segments before and after a heat-setting, fibre shrinkage treatment with steam at 240‹F for four minutes.