Patent GB-535613-A (GB)
Title: Improvements in and relating to the production of pastes from polymerised vinyl chloride
IPC: C08J3/18
Filed: 1939-09-07
Abstract: 535,613. Polyvinyl chloride composition and films ; coated fabrics. RENFREW, A., DAVISON, J. W., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. Sept. 7, 1939, No. 25221. [Classes 2 (ii) and 2 (iii)] [Also in Group VIII] Smooth flowable pastes are prepared from a polyvinyl chloride consisting of 5 to 75 per cent. by weight of soluble polyvinyl chloride and 95 to 25 per cent. of insoluble polyvinyl chloride, by mixing the polymer with a plasticizer or mixture of plasticizers, the proportion of plasticizer in the final paste being 35 to 80 per cent., and the plasticizer being practically non- volatile and such that insoluble polyvinyl chloride is from scarcely soluble to insoluble therein at ordinary temperature. By soluble polyvinyl chloride, is meant soluble in a, etone to an extent of at least 50 per cent. by weight at 20‹ C., and by insoluble is meant soluble in acetone to an extent not more than 15 per cent. by weight. Insoluble polyvinyl chloride may be made by heating vinyl chloride, benzoyl peroxide and soluble starch in the presence of water, and soluble polyvinyl chloride by heating a mixture of vinyl chloride, methyl alcohol and benzoyl peroxide. The plasticizers may be any of those known for use with polyvinyl chloride provided they have the specified solubility characteristics, e.g., tricresyl phosphate, dibutyl phthalate, diamyl phthalate, triethyl citrate, triglyceryl butyrate, ethyl cinnamate or chlorinated diphenyls. The two types of polymer may be mixed and subsequently plasticized, or either the soluble or the insoluble variety or a proportion of the same may be mixed with the plasticizer and the resulting mixture mixed with the remaining polymer. The mixing of the polymers with the plasticizer may be carried out in two stages in a manner similar to that described in Specification 535,612, the first stage comprising mixing the plasticizer with 5 to 10 per cent. by weight of the polymer, and the second stage comprising mixing the remaining polymer with the product of the first stage. Mixing may 'be effected at up to 70‹ C., e.g. at 60‹ C., but when the mixing is effected in two stages, the first stage may be carried out at temperatures up to 120‹ C. when an insoluble polymer, or a mixtureof soluble and insoluble polymers, is employed, and at up to 150‹ C. when the soluble polymeris employed, the second stage being effected at a temperature not exceeding 70‹ C. In examples, pastes are prepared by, (1) mixing- the soluble and insoluble polymers at 20‹ C., adding dibutyl phthalate and mixing at 60‹ C., (2) mixing the insoluble polymer with tricresyl phosphate at 60‹ C., and then mixing in the soluble polymer, (3) mixing the soluble polymer with tricresyl phosphate at 100‹ C., and then mixing at 60‹ with the insoluble polymer, and (4) mixing the soluble and insoluble polymers. at 20‹ C., mixing a part of the mixture with dibutyl phthalate in a steam jacketed mixer, and then mixing with the remaining polymerat 60‹ C. Films or coated fabrics, e.g. leathercloth, may be prepared by spreading the paste on a smooth surface, or a fabric, and gelatinizing by heating at 160‹ C. Specification 500,298 alsois referred to.