Essentially oriented fibers made of synthetic linear polyesters

摘要

1,060,417. Polyester fibres. E.I. DU PONT DE NEMOURS & CO. July 10, 1964 [July 10, 1963], No. 28642/64. Heading B5B. Highly oriented fibres of a synthetic linear polyester on the surface of which are randomlyspaced, discontinuous circumferential ridges of height at least 0À2 microns, occurring with a frequency of 10-130 ridges per mm. of fibre length, are made by a process comprising (1) ageing polyester fibres in contact with a crackproducing agent of molecular weight at least 175 for a time sufficient to produce a fracturable skin on the surface of the fibres; (2) drawing the aged fibres 1À01-1À1 times at a temperature up to 80‹ C. while still in contact with the crackproducing agent, so that a multiplicity of transverse cracks is formed in the fracturable skin; (3) drawing the fibres at least 1À5 times under conditions such that the formation of new cracks or lengthening of existing cracks is avoided. The crack-producing agent may be applied to the fibres in the spinning finish, and may be removed from the fibres before the final stretching in step (3), which may be carried out at above 80‹ C. A crack-producing agent is defined as a compound which promotes cracking on freshly-spun (i.e. less than 1 week old) polyester filaments when such filaments are immersed in the compound or in a solution or dispersion thereof and drawn about 1À5 times under the surface of the liquid. Specified crackproducing agents are high boiling esters, e.g. butyl stearate and isopropyl myristate; polyethers such as poly(ethylene oxide) glycols of mol. wt. 400 to 600, poly(ethylene oxide), glycol monolaurate, copolymers of ethylene oxide and propylene oxide, and high mol. wt. hydrocarbons such as eicosane. The polyester may be polyethylene terephthalate.