GB817771A - Improvements in or relating to the manufacture of crimped multifilamentary yarn of synthetic organic textile material - Google Patents

Abstract

817,771. Crimping yarns. HEBERLEIN & CO., A. G. Oct. 26, 1956 [Nov. 11, 1955; July 3, 1956], No. 32739/56. Class 120(3) Multifilamentary yarn of synthetic organic material e.g. a polyamide, polyester or polyvinyl, having little or no twist (up to 30 turns/metre) is crimped to produce a yarn in which the internal tensions are at least partially compensated. In the crimping process the yarn is temporarily twisted e.g. to 3,000-5,000 turns/metre; heated e.g. with saturated steam under pressure (3 atmospheres) or by air at 200‹- 220‹C. for a period of 2.4 seconds-20 minutes "to set the internal torsional tensions" imparted by the twisting; backtwisted to a normal twist; temporarily twisted e.g. to 2,000-4,000 turns/metre, in the opposite direction to the first such twisting; heated e.g. with saturated steam under 1.3-2.5 atmospheres or by air at 150‹- 180‹C. for a period of 1.5-2.5 seconds "to set the internal torsional tensions"; backtwisted to a normal twist. The yarn is given a permanent twist e.g. 56-80 turns/ metre S or Z, which is stated to be obtained from a formula expressing the number of turns/metre as 2,870 multiplied by the product of "twisting coefficient" (0.3-1) and the reciprocal of the square root of the denier: such twist is imparted prior to or during the process e.g. between the two temporary twisting operations and/or by backtwisting beyond the zero point. One or both temporary twists may be imparted in one step on bobbins (as by means of a ring or uptwisting device) or by false-twisting. The second high twist may be less than the first and the second heat treatment may be effected at a lower temperature and/or for a shorter period than in the first heat treatment.