| 摘要 |
1,086,616. Polyurethane filaments. AMELIOTEX Inc. Jan. 22, 1965 [Feb. 19, 1964], No. 2876/65. Heading B5B. Wet-spun polyurethane filaments containing longitudinal stresses caused by drawing are heated, while supporting by a belt or on rollers in a dryer, to a temperature above the second order transition temperature and below the melting point of the polyurethane for sufficient time to obtain substantially complete relaxation of said stresses. The draw ratio exerted on the filaments before entering the dryer is suitably 1À1 to 3, and that exerted on the filaments in the dryer preferably does not exceed 1À2. In an example, a solution of polyurethane on D.M.F. is spun into a 20% aqueous solution of D.M.F. at room temperature, and the filaments are passed through a countercurrent extraction system comprising stainless steel trays filled with water, the draw ratio between entry and exit of the system being 1À5. The filaments are then transferred to a dryer (17) (not shown) and heated to 130‹, 160‹ and 190‹ C. successively while supported on belts (19), (20) and (21) respectively. The belts may be made of glass fabric impregnated with polytetrafluorethylene. |
