| 摘要 |
1,242,616. Polyvinyl alcohol filaments. KURARAY CO. Ltd. 24 July, 1969 [26 July, 1968], No. 37379/69. Heading B5B. Polyvinyl alcohol filaments of circular crosssection are made by spinning 10 to 30% by weight polyvinyl alcohol aqueous solution of pH 3 to 5 and preferably at 20 to 40‹ C. containing 1 to 5 weight per cent based on the PVA of a water soluble borate salt or bone acid into an aqueous coagulation bath of pH 13À5 to 14 containing 20 to 100 g./l. alkali metal hydroxide and 100 to 180 g./l. sodium sulphate. The soluble salt may be sodium or potassium borate. The alkali metal hydroxide may be sodium or potassium hydroxide. In the examples the as-spun filaments are drawn at a temperature of 15‹ to 35‹ C. at a draw ratio of 2:1, neutralized in a bath containing from 60 to 80 g./l. sulphuric acid and 300 g./l. anhydrous sodium sulphate then submitted to wet-drawing at 15‹ to 35‹ C. at a draw ratio of 2:1 to 3:1, water washed and then dry-heat drawn at a draw ratio at 3:1 to 4:1 1 at 15‹ to 35‹ C. to result in a total draw ratio of 12:1 to 20:1. The filaments so produced have good retention of their extruded cross-section, a homogeneous and compact structure and good drawability. |
