GB921733A - Improvements in the crimping of yarns based on thermoplastic polymers and new yarns obtained thereby - Google Patents

Abstract

921,733. Spinning and finishing yarns. SOC RHODIACETA. April 25, 1961 [April 27, 1960; Jan. 9, 1961], No. 14988/61. Class 120 (3). Crimped or looped yarn is produced by subjecting to the action of a turbulent or whirling current of fluid one or more multifilament yarns of thermoplastic polymer e.g. polyacrylonitrile, polyamide, polyester, polypropylene, to constitute a peripheral yarn, together with one or more yarns e.g. of cellulose acetate, nylon, polyethylene, polyvinyl alcohol, to constitute a core yarn, thereby forming a composite yarn with the peripheral yarn surrounding the core yarn and, after setting the peripheral yarn components of the composite yarn, removing the core yarn and leaving a crimped set yarn of the thermoplastic polymer. The fluid may be compressed air, in which case the composite yarn is subjected to heat setting before removal of the core yarn, or it may be a plasticizing fluid e.g. compressed steam, which sets the thermoplastic polymer yarn components simultaneously with the formation of the composite yarn. The rate of feed of the core yarn to the current is less than that of the peripheral yarn components and may be equal to or slightly higher than the wind-up speed of the composite yarn. The core may be removed by dissolving with a selective solvent, selective melting or stretch-breaking to form short fibres which can be separated e.g. electrostatically, or which are shed during subsequent textile treatments. The crimped yarn may be doubled and/or subjected to a further thermal treatment with or without tension to modify its stretch properties. French Specification 1,096,943 is referred to.