| 摘要 |
535,612. Polyvinyl chloride compositions and films; coated fabrics. RENFREW, A., DAVISON.. J. W., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. Sept. 7, 1939, No. 25220. [Classes 2 (ii) and 2 (iii)] [Also in Grcup VIII] Smooth, flowable pastes are prepared from polyvinyl chloride and a plasticizer or mixture of plasticizers by carrying out the mixing operation in two stages, the first stage comprising mixing the plasticizer with 5 to 10 per cent. of the polymer and the second stage comprising mixing the remainder of the polymer with the product of the first stage, the proportion of plasticizer in the final paste being 35 to 80 per cent. by weight, and the plasticizer being practically non-volatile and such that insoluble polyvinyl chloride is from scarcely soluble to insoluble therein at ordinary temperature. By insoluble polyvinyl chloride, is meant soluble in acetone to an extent not more than 15 per cent. by weight at 20‹ C. The plasticizers may be any of those known for use with polyvinyl chloride provided they have the specified solubility characteristic, e.g. tricresyl phosphate, dibutyl phthalate, diamyl phthalate, triethyl citrate, triglyceryl butyrate, ethyl cinnamate or chlorinated diphenyls. The first stage mixing may be carried out at an elevated temperature, e.g., 60‹ to 120‹ C., whereby a smooth mixture is obtained which is readily mixable in the second stage with the remainder of the polyvinyl chloride, the second stage being carried out at a temperature below 70‹ C. to avoid gelatinization. In examples, pastes are prepared by, (1) mixing polyvinyl chloride with tricresyl phosphate at 120‹ C., and then mixing the syrup at 60‹ C. with the remainder of thepolyvinyl chloride, and (2) mixing polyvinyl chloride with dibutyl phthalate at 60‹ C. and then mixing with the remainder of the polyvinyl chloride at 15‹ C. Films or coated fabrics may be prepared by spreading the paste on a smooth surface or a fabric and gelatinizing by heating at 160‹ C. Specification 500,298 is referred to.
|
