| 摘要 |
Artificial filaments are spun by extruding an acetone solution of a fibre-forming substance into a fatty oil at 45 DEG -70 DEG C., and especially at 48 DEG -56 DEG C., the acetone content of the oil at no time being allowed to exceed the highest concentration of acetone in a binary mixture of the oil and acetone at which a previously unstretched thread of the substance, immersed in the mixture at the spinning temperature, can be stretched without breaking by applying a tension of 1 gram per denier for 2 minutes. The fibre-forming substance may be an acetone-soluble cellulose ester or ether (particularly cellulose acetate), polyvinyl acetate or acetone-soluble copolymers of vinyl acetate with other vinyl compounds, e.g. vinyl chloride. The term "fatty oil" denotes both ordinary and hydrogenated animal or vegetable oils, fats or waxes liquid at temperatures below 45 DEG C. (including commercial varieties containing up to 50 per cent. by weight of free fatty acid), or triglyceride or long-chain alkyl esters of long-chain fatty acids, singly or in mixtures, obtained from these or other sources, the term "long-chain" denoting a chain of 12 or more carbon atoms. Examples of fatty oils which may be used are coconut, palm, sperm and, preferably, arachis oil. In the example a 26 per cent. solution of cellulose acetate in anhydrous acetone is supplied to a spinneret arranged for upward spinning and mounted in an extrusion chamber provided with an inlet for coagulating liquid below the level of the jet face. A tube 12 inches long and 2 inches in diameter is mounted on the extrusion chamber and is provided at the upper end with an overflow gutter. At the beginning of spinning the chamber and tube contain petroleum ether at 20 DEG C. to a depth of 0.5-1 inch above the jet face, but as soon as filament formation has begun this is displaced by arachis oil entering the extrusion chamber inlet at 52 DEG C. The rate of oil feed is so adjusted that when it overflows at the top of the tube it contains 10-12 per cent. of acetone. The filaments formed are drawn from the tube vertically upwards through the atmosphere for 6 feet, pass over guides to wipe off adherent oil, then through a bath of continuously replenished petroleum ether, and finally, after a further short air run, pass to a packaging device. An aliphatic ether, such as di-isobutyl ether, may be used instead of petroleum ether for removing the remaining oil from the filaments. The process is adapted for the production of heavy denier (e.g. 25-35 denier) filaments and artificial bristles. Specifications 695,559 and 697,967 are referred to.
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