| 摘要 |
715,915. Artificial filaments, films &c. AMERICAN CYANAMID CO. Feb. 28, 1952 [March 8, 1951], No. 5261/52. Addition to 672,775. Drawings to Specification. Class 2 (2) The process of the parent Specification for making filaments, films, and other shaped products from a solution of an acrylonitrile polymerization product is modified in that the water-coagulable solution comprises an acrylonitrile polymerization product dissolved in a concentrated aqueous solution of a water-soluble thiocyanate, and the aqueous coagulant, which is used at a temperature not exceeding +10‹ C., is an aqueous solution containing 3-25 per cent. by weight of the same water-soluble thiocyanate. The polymer may be a simple acrylonitrile polymer or it may be a copolymer containing a major proportion by weight of combined acrylonitrile and it may have a molecular weight of 15,000-300,000. The polymer is preferably dissolved in an aqueous solution containing above 40 per cent. of thiocyanate, the upper limit being that of a saturated solution of the thiocyanate. Sodium and calcium thiocyanate solutions are preferred, though other inorganic or organic thiocyanates may be used provided that 'they give highly hydrated ions in aqueous solution. In the production of filaments, the spinning solution may be brought to a temperature of 60-100‹ C. immediately prior to extrusion. The temperature of the coagulating bath may be 0‹ C. or lower, and preferably, the liquid is cooled to the desired temperature and circulated through the coagulating vessel. After leaving the coagulating bath, the filaments may be passed through a washing tank containing hot or cold water and they may then be stretched while passing through a trough containing hot water. In an example, a solution containing about 9 per cent. of a copolymer of acrylonitrile and methyl acrylate in an aqueous solution containing about 49 per cent. of sodium thiocyanate is prepared in an atmosphere of nitrogen and then stored under vacuum until bubble-free. The solution is extruded into an aqueous solution containing 10 per cent. of sodium thiocyanate, the spinning. solution being heated to 75-80‹ C., and the coagulating bath being maintained at -2‹ C. The filaments obtained are passed over and advanced along a pair of mutually inclined rolls while being washed with water at 0‹ C. The filaments are then stretched in water at 99‹ C. and treated with a solution of an anti-static finishing agent, e.g. the diguanidinium salt of octadecyl sulpho-succinate. The filaments are dried and then submitted to a heat-setting treatment while free to contract. Other specified thiocyanates which may be used in the spinning solution and coagulating bath are those of other alkali metals, and of strontium, barium, zinc, tin, lead, guanidine, and substitution derivatives of guanidine. |
