Patent GB-1262766-A (GB)
Title: A highly elasticized composite yarn and a method for manufacturing the same
IPC: D02G3/32
Filed: 1969-05-01
Abstract: 1,262,766. Yarns, ropes and fabrics. KANEGAFUCHI BOSEKI K.K. 1 May, 1969 [6 May, 1968], No. 22395/69. Headings D1F, D1K, D1T and D1W. A single, elastic composite yarn is formed by uniting, without stretching, up to 25% by weight of a yarn A consisting of polypivalolactone fibres the elongation recovery of which can be increased by exposure to heat and at least 75% by weight of one or more other yarns B composed of non-elastic fibres the elongation recovery of which cannot be increased by exposure to heat, and then subjecting the composite yarn, before or after its formation into, or incorporation within, a rope or a knitted, netted, woven or felt fabric, to a thermal treatment at a yarn temperature above 100C but not exceeding a temperature 20C below the melting or decomposition point of any component fibre in the yarn. The term yarn (or fibres) in respect of A includes yarns (or fibres) consisting of pivalolactone homopolymer, those consisting of copolymers of pivalolactone with up to 30 mole% of a comonomer and those made from a mixture of pivalolactone homopolymer and the above copolymers to retain the highly essential crystal configuration of the fibres: such yarn may be a continuous monofilament or formed from multifilaments or staple fibres or blends thereof. The fibres of yarn(s) B may be natural e.g. silk, cotton, jute or wool, or manmade e.g. cellulose acetate, polyamide, polyester, polyether, polyolefin, polyamino acid, polyvinyl alcohol, polyacrylonitrile and may be used in the form of monofilaments, multifilaments, spun yarns, crimped textured yarns, multicomponent yarns or mixed twist yarns, which are unaffected by the thermal treatment. Methods of assembly of the component yarns include (a) forming a covered yarn by helically wrapping at least one of the component yarns around another component (b) forming a core spun yarn by using one component as a core of another during spinning thereof (c) doubling and twisting the component yarns. The thermal treatment e.g. dry heating as in an enclosed chamber or wet heating as in or hot water bath or steam chamber, imparts enhanced elasticity to A with some contraction and, according to the intensity and duration of such treatment (which may be effected simultaneously with, or as part of, finishing and dyeing) and whether free shrinkage, controlled shrinkage or no shrinkage occurs, causes or allows formation of crimps and loops in component yarn(s) B. Yarn for forming into rope is made by spinning a 80/20 blend of polypivalolactone and cotton fibres, covering the spun product with a cotton yarn and heating the yarn assembly at 125C for fifteen minutes in a steam chamber under pressure. Another yarn is formed by spinning a 65/35 blend of polypivaloloctane and cotton fibres, doubling two of such spun products with four polypivaloloctane yarns and twisting the assembly on a ring twister. The yarn product is woven into a satin weave fabric which, after desizing, scouring and bleaching is pretreated in a hot water bath at 120C for two minutes and dyed at 105C for thirty minutes, then washed and finally dried by hot air.