| 摘要 |
1478787 Polyamide yarn E I DU PONT DE NEMOURS & CO 2 April 1975 [3 April 1974 7 Feb 1975] 13468/75 Heading B5B Spin orientated undrawn filaments of polyhexamethylene adipamide are produced by melt spinning the polymer such that the filaments have a birefringence of at least 0À04, cooling the filaments to a non-tacky state and treating them with steam to provide a positive, dry thermal shrinkage between 90‹ and 140‹ C. prior to winding them up under tension. In the process the instantaneous rate of change of birefringence with spinning speed, R, is less than 5 Î 10<SP>-6</SP> minutes/yard, and the filaments are spun at a speed in excess of 2000 yards/minute preferably in excess of 3000 yards/minute. The yarn produced has a birefringence of at least 0À04, a tenacity of at least 2À5 g./denier, a break elongation of 50-115%, a boil off shrinkage of 2-6% a positive dry thermal shrinkage between 90‹ and 140‹ C. preferably one of 0À1- 2À0% and a denier variation valve of 0À5-2À0%.
|
