| 摘要 |
Artificial filaments of high tenacity, lustrous appearance and substantially free of voids are obtained by extruding a solution of polyacrylonitrile in a volatile organic solvent through orifices into a spinning bath consisting of an aqueous solution containing 30-50 per cent by weight of calcium chloride at a temperature of about 100 DEG C. and passing the filaments through the bath until they are substantially completely coagulated. The spinning solution preferably contains from 10 to 30 per cent of the polymer and is extruded preferably at a temperature of 100 DEG to 150 DEG C. Specified <PICT:0584548/IV/1> solvents are dimethyl formamide, dimethyl methoxy-acetamide, N-formyl-morpholine, N-formyl hexamethylene imine, butadiene cyclic sulphone, tetramethylene cyclic sulphone, p-phenylene diamine and the m- and p-nitrophenols. The filaments are preferably maintained under tension during at least part of their travel through the spinning bath and a two-bath system may be employed if desired, in which the first bath consists of aqueous calcium-chloride solution at a temperature of about 100 DEG C., and the second bath may have the same composition as the first or may comprise a different liquid incapable of dissolving the polymer, at a higher temperature, and the filaments may be subjected to a high stretching tension in the second bath. The filaments are finally collected, washed, finished, dried and, if desired, twisted and wound, and they may be heated in a relaxed state to a temperature of 130 DEG to 200 DEG C. to increase their elongation. Referring to Fig. 1, a solution of poly-acrylonitrile in dimethyl formamide is extruded at a temperature of 100 DEG C. through spinneret 1 into spinning trough 3 containing a 40 per cent aqueous solution of calcium chloride maintained at 90 DEG to 100 DEG C. by heating coils 4. The filaments 5 so formed are tensioned by snubbing pins 6, drawn off by roll 8 and collected on bobbin 9. The poly-acrylonitrile preferably has a molecular weight within the range 40,000 to 250,000. Interpolymers containing a major portion of polyacrylonitrile with, e.g. polyvinyl acetate, polyvinyl chloride, polyesters or other derivatives of acrylic or methacrylic acid, polystyrene and polyisobutylene may also be employed. Specifications 404,504, 459,596 and 461,675 are referred to.
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