| 摘要 |
1325297 Polyester filaments FARBWERKE HOECHST AG 12 May 1971 [14 May 1970] 14439/71 Heading B5B In a process for preparing filaments having a low degree of shrinkage and low elongation at break, filaments of a high molecular weight linear polyester are stretched and passed for a total contact time of 0À02 sec. to 0À5 seconds over or around one or more rollers having a surface temperature of from 230‹ to 280‹ C. and are then allowed to relax under a tension of from 0À2 to 10 p/tex (calculated on the final filament titre). The polyester is preferably polyethylene terephthalate, a long list of precursors for other suitable polyesters being given in the Specification. The process is preferably carried out during a continuous spin drawing process in which filaments are melt extruded from spinneret S, passed over sizing roller P and then over or around one or more rollers 1 having a surface temperature of from 80‹ to 120‹ C. to a second pair of rollers 2 having a surface temperature of from 120‹ to 220‹ C., stretching of the filaments being substantially terminated prior to the filaments passing around rollers 2, after which the filaments pass over or around a third set of rollers 3 maintained at a temperature of 230‹ to 280‹ C., the number of turns on rollers 3 being sufficient to attain a contact time of 0À02-0À5 seconds, and then pass under a tension of 0À2 to 10 p/tex to unheated rollers 4. The wind-up speed is suitably in the range 1200 to 3500 m/min., sets of rollers 2 and 3 having circumferential speeds 3À5 to 5À5 and 4À5 to 7 times respectively that of rollers 1. The draw rollers 2 may be replaced by (a) a single roller having a temperature of 120-220‹ C. around which the filaments make “ to ¢ a turn; (b) a heated plate having a temperature in the same range; or (c) jets of super-heated steam having a temperature of 175‹ C. to 450‹ C. |
