| 摘要 |
1,212,786. Hollow fibres. MONSANTO CO. 29 Aug., 1968 [5 Sept., 1967], No. 41314/68. Heading B5B. A hollow synthetic fibre whose cross-section is depicted in the figure has a smooth surface which is essentially devoid of cracks and voids on the fibre surface and has a thick dense skin and large sealed voids within the interior of the fibre which are separated by at least one polymer bridge which connects the interior of the skin at least at two points within the interior structure of the fibre, the bridges being discontinuous along the length of the fibre. In the figure the uncollapsed voids are indicated by shaded areas. The fibre is made by extruding a synthetic fibre-forming polymer dissolved in a solvent into a coagulation bath preferably maintained at below - 10‹ C. and comprising carbon dioxide at or near the saturation level dissolved in a liquid medium which is a non-solvent for the synthetic polymer, a solvent for the polymer solvent and a solvent for carbon dioxide, so as to coagulate the extruded polymer solution by infusion of the medium containing CO 2 into the internal pore structure of the extruded polymer, immediately passing the coagulated filament into a heat-treating zone at temperatures between 50‹ to 100‹ C. The filaments can be stretched, washed and dried by conventional techniques. The fibre-forming polymer is preferably a polymer of acrylonitrile, and preferably contains at least 80% of acrylonitrile. The polymer may be a copolymer of from 80 to 98% acrylonitrile and from 2 to 20% of another monomer containing the > C=C < linkage and copolymerizable with acrylonitrile. A large number of suitable mono-olefinic monomers are given. The polymer may also be a ternary or higher interpolymer. Preferably, the ternary polymer comprises acrylonitrile, methacrylonitrile and 2-vinylpyridine. The polymer may also be a blend of a polyacrylonitrile or of a binary interpolymer of from 80 to 98% acrylonitrile and from 1 to 20% of at least one other -C=C- containing substance with from 2 to 50% of the weight of the blend of a copolymer of from 10 to 70% of acrylonitrile and from 30 to 90% of at least one other -C=C- containing polymerizable monomer. The polymers or polymer blends are normally dissolved in highly polar organic solvents such as dimethylformamide, dimethylacetamide and dimethylsulphoxide to form a viscous solution having 10 to 30% solids for wet spinning. The coagulating liquid is preferably methanol or ethanol.
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