| 摘要 |
954,553. Treating polyacrylonitrile. CRYLOR. July 29, 1960 [July 30, 1959], No. 26571/60. Heading B5B. Undrawn filament of acrylonitrile polymer are subjected at least once between their consolidation and final drawing to the action of a liquid consisting of or comprising as the major component, an aliphatic ketone. Acrylonitrile polymers are defined as acrylonitrile homopolymer, or copolymers and grafted polymers containing at least 85% of acrylonitrile and mixtures of such polymers. Undrawn filaments are defined as monofilaments, yarns or tows made by wet or dry spinning before they have undergone their complete drawing. They may have undergone washing or a preliminary drawing. Filaments are said to be consolidated when as a result of any spinning process, they have set to such an extent that their mechanical strength is sufficient to withstand normal textile treatments, e.g. winding-up. The filaments may be immersed in an aliphatic ketone, e.g. acetone, methyl ethyl ketone or diethyl ketone, before or after elimination of spinning solvent. The treatment may comprise removal of solvent by washing with a ketone. The treatment may be continuous or discontinuous, e.g. a wound package of filaments may be immersed in a ketone bath or yarn may be continuously passed therethrough. The ketone bath, or the last bath if several are used, preferably contains an oiling-agent, e.g. butyl stearate. Preferably, the treatment is carried out as closely as possible to the final drawing stage. In an example, a polyacrylonitrile yarn obtained by dry spinning is washed with water to remove solvent, collected in a perforated pot, and successively immersed in two baths comprising 70% acetone and 30% water. The yarn thus treated has improved drawing properties.
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