| 摘要 |
950,661. Treating polyacrylonitrile. AMERICAN CYANAMID CO. Aug. 10, 1961, No. 28953/61. Heading B5B. [Also in Division D1] The dyeability of previously hot-stretched filaments of an acrylonitrile polymer containing at least 80% by weight of acrylonitrile is improved by drying the filaments in the gelled state at a dry-bulb temperature of 200- 260‹ F., the relative humidity falling between the lines AA and DD. Drying is continued until substantially all the water has been evolved from the filaments and the structure has collapsed. The filaments are then treated in a relaxed state in steam at 105-160‹ C. Before the drying stage, the gelled, stretched filaments may be rinsed in water. After the drying stage, but before the steam treatment, the collapsed filaments may be immersed in a reducing solution at pH less than 7.0. The acrylonitrile polymer may be a homopolymer or a copolymer of acrylonitrile with one or more mono-ethylenically unsaturated compounds, e.g. methyl acrylate, methyl methacrylate, acrylamide, vinyl chloride, vinylidene chloride, vinyl acetate, p-styrene sulphonic acid, vinyl pyridine and 2- methyl-5-vinyl pyridine. In an example, a copolymer of acrylonitrile and methyl methacrylate is extruded into aqueous calcium thiocyanate, washed, stretched in boiling water, and dried in air at 110‹ C. and relative humidity 18% until the water content is less than 1%. The filaments are then immersed in water or in 10% aqueous sodium bisulphite, heated in relaxed condition with steam at 125‹ C. and dried at 95‹ C. to less than 1% water content. The filaments are immersed for 60 minutes in a dyebath at 95‹ C. containing 1% Sevron Brilliant Red 4G, 3% ammonium acetate, and 5% retarder LAN. Dye-bath ratio is 1: 100. In a further example, filaments are immersed for 80 minutes in a dye-bath at 93‹ C. containing 2% Calcofast Wool Bordeaux BB, 4% sulphuric acid, and 5% Glaubers salt. Dyebath ratio is 1:60. Specifications 714,530 and 732,135 are referred to.
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