| 摘要 |
Artificial filaments are made by dry-spinning a solution containing a water-insoluble ether of dextran and nitrocellulose (blended in a ratio of at least 4 : 1 by weight) in a volatile organic solvent capable of dissolving both. The dextran may be produced by the action of a bacterium such as Leuconostoc mesenteroides or L. dextranicum, or of the enzyme of the bacterium, on sucrose. The dextran ether may be a water-insoluble ethyl ether obtained by the ethylation of dextran with an ethylating agent such as ethyl chloride, as described in U.S.A. Specification 2,344,179. The preferred nitrocellulose is of the low viscosity type soluble in "Cellosolve" (Registered Trade Mark), ethyl acetate, butyl acetate and cyclohexanol acetate and containing 10-12.5 per cent of nitrogen. The composition may also contain nitrocellulose plasticizers such as castor oil, camphor, diethyl or diamyl phthalate or butyl stearate. Nonsolvent diluents such as toluene, benzene and the petroleum naphthas may also be present. In an example a spinning solution containing 60 per cent by weight of a water-insoluble benzyl ether of dextran containing about 1.5 benzyl groups per anhydro-glucose unit of the dextran, 15 per cent of low-viscosity nitrocellulose and 25 per cent of "Cellosolve" is extruded through a spinneret into a spinning cell through which a current of air at 150-200 DEG C. is passed concurrently with the extruded filaments, the dry filaments emerging from the bottom of the cell being wound on a rotating drum. In another example filaments are similarly dry-spun from a mixture of 73.3 per cent ethyl dextran containing about 2 ethyl groups per anhydro-glycose unit of the dextran, 8.3 per cent of low-viscosity nitrocellulose, 1.7 per cent of castor oil and 16.7 per cent of "Cellosolve."
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