GB1254923A - Novel polyester textile article and process for its manufacture - Google Patents

Abstract

1,254,923. Crimped multifilament yarn. SOC. RHODIACETA. 18 March, 1969 [18 March, 1968], No. 14296/69. Headings D1F and D1W. A textured multifilament polyester yarn is characterised in that the individual filaments have substantially zero twist torque and a crimp in the form of rounded castellations (as distinct from saw-tooth crimp), the filaments being generally loosely interconnected. A process for producing the yarn comprises partially stretching a multifilament yarn of a synthetic thermoplastic material in contact with a crackpromoting agent, giving the yarn a heat treatment in a relaxed condition, and knitting, setting and deknitting the yarn. In a preferred embodiment the setting step between the knitting and deknitting steps constitutes at least part of said heat treatment. The first part of the heat treatment is preferably effected under conditions of thermal shock. The partial stretching and heat treatment of the yarn may be carried out as separate operations or as a continuous process. In a preferred embodiment of the process, the yarn is partially stretched in contact with a crack-promoting agent, e.g. an aqueous solution of a lower aliphatic alcohol, is knitted into a strip and the strip is rapidly immersed for a short time in boiling water, and then heated for several minutes in hot air or steam, after which the strip is deknitted. After the initial partial stretching and heat relaxation step, the yarn may be subjected to a supplementary stretch and relaxation treatment, during at least one of which or during the initial partial stretching, the degree to which the length of yarn is being altered is varied regularly or randomly. The yarn treated is preferably of polyethylene terephthalate.