GB559369A - Improvements in and relating to the treatment of nylon yarns - Google Patents

Abstract

559,369. Setting synthetic yarns. IMPERIAL CHEMICAL INDUSTRIES, Ltd. July 29, 1942, No. 10584. Convention date, July 30, 1941. [Classes 120 (ii) and 120 (iii)] [Also in Group IV] A nylon yarn is subjected to a twist-setting operation to reduce twist liveliness, the operation comprising a hot wet treatment of the yarn at a temperature between 135‹F. and 190‹F. and at a relative humidity in excess of 50 per cent while the yarn is maintained under a sufficiently low tension to permit it to shrink. The treatment is such that no objectionable yarnsetting takes place. In an example, an unsized yarn of polyhexamethylene adipamide is wound into skeins and twist-set at 170‹F and 88 per cent relative humidity while permitting free shrinkage without untwisting or snarling. In another example, a polyhexamethylene adipamide yarn sized with a partially hydrolysed polyvinyl acetate size containing boric acid and polyethylene oxide is wound on a bobbin with a collapsible shell. After winding, the shell is removed and collapsed to permit shrinking of the yarn. The yarn is then treated as in the previous example. In a further example, a polyamide yarn of low twist is subjected to up-twisting, at 30 feet per minute, and between the balloon pigtail of the up-twister and the take-up bobbin, the yarn under a low tension is passed through a moistening device and then through a slot 3.5 inches long in a copper block electrically heated to 239‹F. The effect is equivalent to that of a static treatment at 170‹F. The yarn is subsequently coned and knitted. A sized polyamide yarn in the form of a warp is moistened by a roller running in a trough of water, and is then passed through a heating tunnel at 221‹F at high speed but under a low tension. The heat required in the twist setting operation may be provided by hot water, steam, heated air, heated metal plates, infra-red rays, hot gases or vapours, warm alcohol or similar swelling agents. For setting the twist of very highly twisted yarn e.g. a 30 denier yarn having 50 turns per inch, the yarn may be twisted to a higher degree than required, then twist-set, and then back twisted a few turns per inch to the required degree of twist. The twist setting may be carried out in two or more stages e.g. it may be carried out in part while the yarn is on a size bobbin and completed during the subsequent coning operation. The treatment may be carried out on mixed yarns containing mainly nylon, with a minor proportion of cotton, regenerated cellulose, cellulose acetate, or other filaments. Specifications 461,236, 461,237, [both in Group IV], 519,038 and 553,303, [Group IV], are referred to.