| 摘要 |
1279574 Fibres containing polyvinylchloride particles IMPERIAL CHEMICAL INDUSTRIES Ltd 14 Dec 1970 [15 Jan 1970 2] 2049/70 and 2050/70 Heading B5B [Also in Division C3] A method of improving the coherance and strength of a spun filamentary structure containing discrete particles of vinyl chloride polymer embedded in a coagulated matrix (different from a fibre-forming polymeric material) provided by spinning a dispersion of vinyl chloride polymer in a solution of at least one matrix through at least one orifice into a coagulant for the matrix, comprises introducing into the spun structure a coalescent for the vinyl chloride polymer particles and heating the structure containing the coalescent to effect coalescence of the vinyl chloride polymer particles without significantly degrading the vinyl chloride polymer. The spun structure containing vinyl chloride polymer particles is passed through a heating chamber with the temperature of the chamber and the residime time of the fibre therein being chosen to effect the heating. The coalescent may be introduced by passing the spun structure through a medium consisting of or containing coalescent or the coalescent is included in the dispersion of vinyl chloride polymer from which the spun structure is produced. The concentration of coalescent, in the dispersion from which the spun structure is produced is preferably 4 to 25% by weight of the vinyl chloride polymer in the dispersion. The vinyl chloride polymer is suitably obtained by polymerisation of vinyl chloride in an aqueous medium at a temperature below O‹C, preferably below -15‹C. It may be necessary to use an antifreeze in the aqueous medium e.g. ethylene glycol a methonal and of such is used its concentration in the aqueous medium should preferably be reduced to a concentration below 5% by volume of water before addition of coalescent, otherwise undesirable agglomeration of vinyl chloride polymer particles may take place on addition of the coalescent. A suitable method of reducing the concentration of antifreeze is by dialysis. Preferably the polymerization is effected in the presence of soluble salt of a sulphonic acid derivative of an alkyl phenoxy polyetheralcohol as a dispersion stabiliser where R is an alkyl group having 5 to 20 C atoms and n is from 2 to 12. A convenient upper limit of size of the vinyl chloride polymer particles is 2Á in diameter and generally they are 0.05 to 0.2Á in diameter. Preferably the concentration of vinyl chloride polymer is at least 15% by weight. Suitable matrices are poly vinyl alcohol and sodium alginate. The matrix is preferably incorporated in the dispersion by mixing an aqueous dispersion of polymer particles with an aqueous solution of the matrix but it is also possible to dissolve the matrix in an aqueous dispersion of the polymer or to disperse the polymer particles in an aqueous solution of the matrix. A concentration of 5 to 20% of matrix by weight of vinyl chloride polymer in the mixture is preferred. Where the matrix is polyvinyl alcohol and/or sodium alginate suitable coagulents include acetone and methanol and solutions of metal salt e.g. calcium chloride, in methanol. Solvents or swelling agents for vinyl chloride polymer which are suitable for use as coalescents include N-methylpyrollidone, tetrahydrofuran, cyclohexanone, sulpholane, hexamethyl phosphoramide nitrobenzene, ethylene carbonate, propylene carbonate, #-caprolactam, 2:2<SP>1</SP> dimethylvalerolactam, dimethylacetamide and dimethylformamide.
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