Patent GB-948576-A (GB)
Title: Treating filaments and fibers of synthetic polymers
IPC: D02J1/22
Filed: 1962-12-14
Abstract: 948,576. Crimped filaments. E. I. DU PONT DE NEMOURS & CO. Dec. 14, 1962 [Dec. 26, 1961], No. 47261/62. Heading B5B. Filaments of a crystallizable, thermoplastic polymer having an asymmetric birefringence differential across their diameter are drawn at a temperature above the second order transition temperature Tg of the polymer, and cooled by contacting them substantially immediately after they have been drawn, with a liquid maintained below Tg. Linear condensation polyesters e.g. polyethylene terephthalate, polyethylene terephthalate/isophthalate (85/15), polyethylene terephthalate/5 - (sodium sulpho) isophthalate (97/3), poly(p - hexahydroxylyene terephthalate), poly(diphenylol propane isophthalate), poly(diphenylolpropane carbonate), the polyethylene naphthalenedicarboxylates (especially those derived from the 2,6- and 2,7- isomers) and poly(m-phenylene isophthalate) are preferred. Filaments may be drawn in the presence of a liquid maintained above Tg and then cooled by contacting them with a liquid maintained below Tg at a point just after the draw point. The cooling liquid may be water, which may contain textile finishes, or antistatic agents in solution or dispersion, or other inert liquid, e.g. kerosene mineral oil, or propanol. In a preferred method a crystallizable, thermoplastic linear condensation polyester is welt spun to form filaments which are jet quenched to produce an asymmetric birefringence differential across the diameter of the filaments, and the filaments are drawn in the presence of water maintained at a temperature above Tg and then cooled to a temperature below Tg by contacting them substantially immediately after they have been drawn, with water at a temperature below Tg. In the spinneret of Fig. 1, polymer flows through channels 2 into annular polymer distribution space 3 and through orifices 4 in the spinneret plate 5 to form filaments 6 which are immediately quenched by a strong flow of gas from annular nozzle 7. Gas enters the nozzle via conduit 8 and flows through foraminous members 9 from vertical annular opening 10 across the filament bundle. The insulating disc 12 and insulating ring 14 keep the spinneret temperature uniform despite the use of high velocity quenching gas. The depth of ring 14 is chosen so that the nozzle 7 is spaced at the required distance from the spinneret face. Filaments so made show an asymmetric birefringence differential across their diameter. Conventional winding means (not shown) are used. In apparatus as shown, a tow of filaments 20 is passed around feed rolls 21-24, through pre-wetting vessel 29 containing an aqueous bath at room temperature or at 40-70‹ C. and thence around feed rolls 25-28, which may be sprayed with the same aqueous bath at the same temperature. Drawing is effected as the tow passes under hot spray, at a temperature above Tg, from nozzles 39, and the tow is immediately cooled by a spray of cool liquid at a temperature below Tg from nozzles 40, and passes to the draw rolls 31-38, some or all of which may be liquid cooled to facilitate cooling of the drawn tow. As shown, draw roll 31 is hollow and cooling liquid enters at 51 and is removed at 53. 44 is a temperature measuring device. The tow is now passed around puller rolls 45, excess liquid squeezed out by rolls 46, opened by passage through air jet 47, laid on conveyer 48 and dried in the chamber 49. On release of tension, the filaments exhibit three-dimensional crimp. Drawing may be effected by passage through steam, other hot vapour, or by the use of a heated block and snubbing pin, in place of the liquid medium. U.S.A. Specifications 2,556,295 and 2,667,964 are referred to.