| 摘要 |
In an example, a solution containing 789 mls. dimethyl formamide, 336 mls. acetone, 450 mls. acrylonitrile, 30 mls. methyl acrylate, 4.5 gms. itaconic acid, and 7.5 gms. azobisisobutyronitrile was heated at 50 DEG C. for 24 hours to give an acrylonitrile copolymer solution having an intrinsic viscosity of 1.6 at 25 DEG C., in dimethyl formamide.ALSO:High-bulk polyacrylonitrile yarn is made by extruding a polyacrylonitrile solution through a multi-hole jet having holes of at least two sizes, each of at least 20% of the holes having a cross-sectional area less than half that of the average of the remaining holes, into a liquid coagulating medium to form filaments and in which each freshly coagulated filament has a cross-sectional area which at the most is equal to that of the hole from which it issues, and taking up the filaments at substantially the same linear speed. Coagulation of the filaments may be accompanied by a reduction in their cross-sectional area. Suitably, the spinning solvent contains a major proportion by weight of dimethyl formamide, dimethyl acetamide or dimethyl sulphoxide and also an aromatic hydrocarbon. The coagulant may also be an aromatic hydrocarbon, e.g. benzene, toluene, or xylene, or a mixture of any two of these. In the high bulk continuous filament yarn so made the filaments are of at least two deniers, of which one is less than half the other, the smaller denier filaments being present to the extent of at least 20% of the number of filaments in the yarn and comprising more highly orientated polyacrylonitrile than that in the larger denier filaments. Acrylonitrile homopolymers, and copolymers containing at least 80% acrylontrile, preferably 90-95% with styrene, methyl acrylate, itaconic acid, methallyl sulphonic acid and its salts, vinyl acetate, and vinyl pyridine, may be used. |
