| 摘要 |
Hollow filaments are obtained by extruding into an aqueous coagulating medium at a temperature of at least 40 DEG C. a solution of a hydrophobic synthetic linear polymer in an organic solvent miscible with water and containing dispersed therein a substance capable of generating gas in contact with the coagulating medium, the concentration of the organic solvent in the coagulating medium being limited so that the swelling effect of the coagulating medium on the polymer is insufficient to cause cementing of the filaments at points where they are pressed together. The coagulating medium may be acidic or alkaline. When sodium bicarbonate or calcium carbonate is used as the gas-producing substance, the coagulating bath is made acidic. Ammonium chloride and ammonium sulphate require the coagulating bath to be alkaline. The filaments may be made from polyvinyl chloride, chlorinated polyvinyl chloride, vinyl acetate-vinyl chloride copolymers, vinyl chloride-acrylo-nitrile copolymers. The solvent may be acetone, dioxane, or tetrahydrofurane. The filaments may be produced with or without stretching. They may be cut to staple fibre, spun and knitted or woven. They may be used in the production of padding p or insulating material. Specification 580,370, as open to inspection under Sect. 91, is referred to.
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