| 摘要 |
<PICT:0583939/IV/1> <PICT:0583939/IV/2> 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 glycerine heated to a temperature of at least 100 DEG C. 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 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 glycerine at a temperature of at least 100 DEG C., and the second bath of glycerine or other 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 in Fig. 1, a solution of poly-acrylonitrile in dimethyl formamide is extruded at 100 DEG C. through spinneret 1 into spinning trough 3 containing glycerine heated to 140 DEG C. by heating coil 4. The filaments 5 so formed are tensioned by snubbing pins 6, drawn off by roll 8 and collected on bobbin 9. In the two-bath system of Fig. 3, the filaments 35 are formed in spinning trough 33 containing glycerine at 120 DEG C., and passed through a second trough 39 containing glycerine at 170 DEG C. in which they are tensioned by pins 43. The poly-acrylonitrile preferably has a molecular weight within the range 40,000 to 250,000. Interpolymers containing a major portion of poly-acrylonitrile 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, 461,675 and 585,367 are referred to.
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