| 摘要 |
Fibres and other shaped articles containing acrylonitrile polymer are produced by extruding a solution of a cross-linked acrolonitrile polymer into a liquid hydrocarbon coagulant which is completely miscible with the polymer solvent at the spinning temperature. The acrylonitrile polymer usually contains up to 15 mols. per cent (based on monomeric acrylonitrile) and preferably 2-8 mols. per cent of copolymerized mono-ethylenically unsaturated monomers, such as acrylic or methacrylic acids and their amides and esters, vinyl acetate and chloride, vinylidene chloride, and methacrylonitrile, and 0.001-0.3 mols. per cent of a polyethylenically unsaturated cross-linking compound. Suitably, the polymer contains 0.02-0.06 mol. per cent of such bi-ethylenically unsaturated compounds as divinyl benzene, methylene bisacrylamide, diallyl phthalate, ethylene glycol diacrylate or butadiene derivatives, or 0.005-0.02 mol. per cent of such tri-ethylenically unsaturated compounds as triacylo-hexahydrotriazine or diallyl malleate. Alternatively if the polymer contains reactive acid groups certain polyvalent metallic compounds which react to form "salt bridges," e.g. magnesium or aluminium sulphate, may be used as cross-linking agents. The polymer solvent is suitably dimethylformamide or dimethylacetamide, in which case the hydrocarbon coagulant should contain no more than 50% aromatics, or dimethyl sulphoxide or ethylene carbonate when the coagulant should contain 40-100% aromatics. Kerosene, with or without aromatics, is a suitable coagulant, and spinning is preferably carried out at 80-150 DEG C. with either co- or counter-current flow of coagulant. The fibre obtained is stretched at 100-150 DEG C. to 3-10 times original its length while it still contains 3-15% residual solvent and 2-15% coagulant. This residuum should thereafter be removed by treating the product for some time at temperatures above 80 DEG C. with hot aqueous ethanol, with a boiling solution of non-ionic detergent, or with steam, and the fibre obtained is then dried, above 100 DEG C. if a translucent, vitreous, compact product is required, or below 100 DEG C. if a porous, opaque, rugged product is preferred. If, before drying, the fibre is boiled in 10% salt solution it does not turn opaque even at low drying temperatures. If desired, the fibres before drying may also be treated with a cationic surface active agent. The solvent and coagulant may readily be separated from the spent coagulant by cooling and separating the phases which form. Water may be added to facilitate this separation but the solvent phase will then need to be redistilled to recover the solvent. Specification 824,226 is referred to.
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