| 摘要 |
955,228. Voided acrylic fibres. TOYO RAYON KABUSHIKI KAISHA. Oct. 30, 1962 [Nov. 8, 1961], No. 41079/62. Drawings to Specification. Heading B5B. Acrylic fibres having voids therein are made by mixing an isocyanate with a wet-spinning solution of an acrylic polymer containing substantially no water, spinning the mixture into a coagulating bath comprising a mixture of water and an organic solvent, and drawing the spun filaments, the concentration of polymer in the spinning solution being from 10-27% by weight (preferably 15-20%) and the amount of isocyanate being from 0.5 to 100% of the weight of polymer in the spinning solution. Acrylic polymers are defined as containing at least 85 mol. per cent acrylnitrile units. Specified isocyanates include tolylene di-isocyanate, phenyl isocyanate, ethyl isocyanate, hexamethylene di-isocyanate, diphenylmethane diisocyanate, naphthylene di-isocyanate, nitrodiphenyl diisocyanate and diphenylsulphondiisocyanate which may be added in a proportion of 10-50% by weight based on the polymer in the spinning solution. Specified spinning solvents include dimethylformamide, diethyl formamide, dimethyl acetamide, dithyl acetamide, ethylene carbonate, dimethyl sulphoxide,γ- butyrolactone and acetone. Organic solvents suitable for the coagulating bath, which preferably contains 30-70% by weight of water and 70-30% by weight of the organic solvent, include dimethyl formamide, diethyl formamide, dimethyl acetamide, diethyl acetamide, ethylene carbonate,γ-butyrolactone, tetrahydrofuran, acetone, dioxane, methanol, ethanol, butanol, propanol and thioglycolic acid. Bath temperatures of 5-80‹ C. may be used. The spun filaments may be drawn 2-7 times their original length in known manner, and heat-relaxed 10-30% in steam.
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