| 摘要 |
A composition suitable for making microporous fibres of a vinyl chloride polymer of vinyl chloride content 85-100% having a density substantially below 1.4, contains as a porogenous component, dispersed in the solution, 2-25% (based on the weight of the polymer) of a water-soluble alcohol soluble to an extent above 2% (based on the weight of the polymer) in the solvent, chemically stable under the spinning conditions free from a tendency to leave the polymer with the solvent in a spinning operation, and incompatible with the polymer and insoluble in the solution of the polymer, and capable of being removed chemically unchanged from the fibres formed. Thus, in dry spinning the porogenous substance should be less volatile than the spinning solvent, and in wet-spinning the porogenous substance should be insoluble in the coagulating bath. The spinning solution may be made by first dissolving the porogenous substance in the spinning solvent, and then dissolving the polymer in the solution so obtained, causing separation of the porogenous substance as a fine uniform dispersion. The porogenous substance may be a mono-, di-, or polyhydric alcohol, e.g. allyl alcohol, isobutyl alcohol, ethylene glycol, polyethylene glycols, especially those with 1-5 ether linkages e.g. diethylene glycol, hexaethylene glycol, and trialcohols e.g. glycerol. Removal of the porogenous substance from the fibres may be effected by solvent extraction either in a special operation or in a finishing treatment. The porogenous substance is water-soluble it may be extracted from the fibres with water or other aqueous liquid. Specified dry spinning solvents include tetrahydro furan, ethylene oxide and propylene oxide, and a mixture of carbon disulphide, benzene or perchloroethylene with acetone. Dimethyl formamide is specified as a wet-spinning solvent, to which isobutyl alcohol is added as the porogenous component, and the mixture is wet-spun into a mixture of dimethyl formamide and water. Filaments so made may be stretched by up to 5 times their original length in boiling water, and then shrunk if desired, also in boiling water. The density of the filaments obtained is from 0.9-1.35. |
