ES363444A1 - Process for relaxing internal tensions of textured synthetic yarns - Google Patents

Abstract

A process for equalising the internal tensions in synthetic textile yarns which have been textured by temporary high-twisting and heat setting in the highly twisted state comprises subjecting the yarn to further temporary high twisting in the direction opposite to that in which it was previously high twisted but without a heat setting treatment in the high twisted state, the yarn being subjected to a heat treatment either before or after the said further temporary high twisting. In a preferred embodiment, a multifilament yarn 2 is fed from a bobbin 1 via feed rollers 3 and a heater 4 to a false twister 5. The heat set highly twisted yarn then passes through feed rollers 6 to a heating device 7, to equalise internal tensions in the yarn, and is taken off by feed rollers 8 rotating at a speed 10-15% slower than that of the feed rollers 6 to allow the yarn to contract. The rollers 8 feed the equalised yam to a second false twister 9, which rotates in the opposite direction to the false twister 5, and the yam is fed to a takeup package 11 by feed rollers 10. The yam is preferably slightly stretched during the second false twist treatment. The heaters 4 and 7 are preferably heated contact surfaces but may be hot air heaters. In an alternative embodiment, the yam after the first false twist and heat setting treatment is wound into a package which is steamed in an autoclave to equalise internal tensions in the yarn. The yam is then taken from the steamed package and passed through a false twister so that a twist is imparted in the opposite direction to the first applied twist, and the yarn is wound into a package. In a further embodiment, the heat treatment to equalise internal tensions may be combined with subsequent necessary yarn treatment processes. Yarns specified are multifilament polyamide or polyester yarns of 100-200 denier.