| 摘要 |
<p>Crimped polyacrylonitrile filaments are produced by passing polyacrylonitrile filaments which have been wet-spun and not subsequently dried at an elevated temperature and under stretching tension over an edge and subsequently immersing the stretched filaments, under conditions allowing them to shrink, in an aqueous bath at a temperature of 70 DEG -100 DEG C. The edge may have a radius of curvature of 2 to 40 thousandths of an inch and may enclose an angle of 30 to 140 degrees. The edge may be made of stainless steel, a ceramic material or compressed asbestos. The filaments may be stretched to 8 to 14 times their original length while being maintained at 50 DEG -100 DEG C.; heating may be effected in 2 or more stages. After passing the edge the filaments may be cooled by contact with air or water at 20 DEG C. before treatment in an aqueous bath containing a wetting agent at 80 DEG -92 DEG C. The term polyacrylonitrile includes copolymers containing at least 80% acrylonitrile with styrene, methyl acrylate, itaconic acid, methallyl sulphonic acid and its salts, vinyl acetate and vinyl pyridine. The crimped filaments obtained should be dried, preferably at 70 DEG -150 DEG C., under a tension preferably not exceeding 10 mgms./denier. The angle between the path of travel of the filaments approaching the edge and their path of travel when leaving the edge is preferably about 60-150 degrees; particularly 80-120 degrees. Specification 910,323 is referred to.</p> |
