| 摘要 |
A rigid cross-linked cellular product containing closed cells is prepared by heating in a mould under pressure, a mixture of a polymer or copolymer of vinyl chloride, a polyisocyanate, a blowing agent which gives a gas on thermal decomposition, an ethylenically unsaturated anhydride, another ethylenically unsaturated monomer and 5-30% of a saturated halogenated hydrocarbon boiling between - 50 DEG and +100 DEG C. at normal pressure, cooling the mixture, removing it from the mould and treating it with hot water or water vapour. A polyethylenic copolymer chain is grafted on to the vinyl chloride polymer. The composition may contain 20-95% polyvinyl-chloride, 0.5-60% polyisocyanate, e.g. p,p1,p11-triisocyanatotriphenyl methane, p,p1 - diisocyanatodiphenylmethane, or toluene-2,4- and 2,6-diisocyanate, 2-30% of an unsaturated anhydride, e.g. acrylic, citraconic, itaconic or maleic, 2-30% of another unsaturated monomer, e.g. buta-1,3-diene, isoprene, dimethyl buta-1,3-diene, chloroprene, 3 - cyanatobuta - 1,3 - diene, piperylene, myrcene, vinyl chloride, vinylidene chloride, styrene, p-chlorostyrene, 3,5-dichlorostyrene, p-methoxystyrene, methyl acrylate, octyl acrylate, methyl methacrylate, lauryl methacrylate, acrylonitrile, a -chloroacrylonitrile, methacrylonitrile, dimethylacrylamide, vinylpyridine, vinyl benzoate, vinyl ketones and ethers, vinyl carbazole, ethylene, propylene, isobutylene, divinylbenzene, vinylacetylene, and/or vinyl ethynyl carbinol, and 5-30% of a halogenated hydrocarbon, e.g. CCl4, CHCl3, CCl3F, CCl2F2, CHClF2, C2Cl3F3. Swelling agents specifie are azodiisobutyronitrile and azodicarbonimide. 0.1-10% of catalyst may be added. The mixture is initially heated to 160-200 DEG C. In typical examples mixtures of polyvinyl chloride, toluene diisocyanate, maleic anhydride, azodiisobutyronitrile, and (I) styrene and CCl3F, (II) acrylonitrile and CCl3F, and (III) styrene and C2Cl3F3 were heated at 175 DEG C. under pressure, in a mould, cooled, removed from the mould and placed in a damp enclosure at 100 DEG C. Specification 985,461 is referred to. |
