| 摘要 |
Polymers and copolymers of vinyl chloride are stabilized against thermal decomposition by a tri-alkyl tin mono-alkoxy compound in which the alkyl radicals are such that the corresponding tri-alkyl tin chloride is soluble in the polymeric composition. Preferably the alkyl radicals contain at least 4 carbon atoms and the alkyl radical of the alkoxy group contains from 1 to 8 carbon atoms. Tributyl tin mono-ethoxide and butoxide and tri-n-octyl mono-ethoxide are specified. The stabilizers may be added before, during or after polymerization. The compounds probably react with hydrogen chloride to produce the trialkyl tin chloride and the alkanol. One of these may be removed by volatilization during processing. Copolymers which may be stabilized include those of vinyl chloride with acrylic and methacrylic esters, acrylonitrile, maleic and fumaric acid esters (including the dihexyl and dibenzyl esters), itaconic and aconitic acid esters, vinyl esters (including the chloroacetate and methoxy butyrate), esters of glycol monoalkyl ethers, and vinylidene chloride. Compositions containing also dibutyl phthalate, dioctyl phthalate, methyl glycol phthalate, tricresyl phosphate and stearic acid are exemplified. Specification 692,556 [Group IV (b)], is referred to.ALSO:Tri-alkyl tin mono-alkoxides are prepared by reacting a tri-alkyl tin mono-halide with an alkali metal alkoxide. The halide may be added to a solution of the alkoxide in the corresponding alcohol, or the dry, powdered alkoxide may be reacted with an ethereal solution of the halide. The alkali metal halide is precipitated and the tri-alkyl tin alkoxide may be recovered by distilling the filtered solution under reduced pressure. Preparations of tri-n-butyl tin monobutoxide and tri-n-octyl tin mono-methoxide are described in detail. The required tri-alkyl tin halide may be prepared by heating a mixture of a tetra-alkyl tin and a tin tetrahalide, or by first forming the alkyl magnesium halide by Grignard methods and reacting it with a solution of tin tetrahalide. Specification 692,556 is referred to. |
