| 摘要 |
An organosilicon polymer of the average general formula: <FORM:0957554/C3/1> in which each R is a monovalent radical of 1 to 18 C atoms, free from aliphatic unsaturation, and is a hydrocarbon, halohydrocarbon or cyanoalkyl radical, each Z is a divalent hydrocarbon radical of 2 to 18 C atoms and is free from aliphatic unsaturation, each R1 is a monovalent radical of less than 5 C atoms and is a haloalkyl radical having no halogen alpha to the oxygen or an alkyl radical, y is 0, 1 or 2, x has a value of at least 3 and a is 2 or 3, is best made by reacting a siloxane of the formula: RySi[(OSiR2)xH]4-y with silanes of the formula R11SiR3-a(OR1)a, in which R11 is a monovalent hydrocarbon radical containing aliphatic unsaturation, in the presence of a Pt catalyst. Alternatively the reactants can be RySi[(OSiR2)xR11]4-y/t and HSiR3-a(OR1)a. The products are benzenesoluble and set to insoluble gels on exposure to moisture, especially in the presence of a catalyst for the reaction of alkoxy groups with water or SiOH. Catalysts specified are metal monocarboxylates, organotitanium esters, amines, amine salts, quarternary amine salts and carboxylic and inorganic acids. Organic and inorganic fillers and metals may be added. In a typical example (1) chloroplatinic acid was added to a mixture of a dimethylhydrogensiloxy-terminated dimethylpolysiloxane and vinyltrimethoxysilane, and the resulting mixture was heated at 125 DEG to 130 DEG C. and finally at 145 DEG C. to yield a straw coloured liquid of the formula: <FORM:0957554/C3/2> Si(CH3)2(CH2)2Si(OCH3)3 This compound when mixed with tetraisopropyltitanate (Ex. 3) and exposed to air at room temperature, cured to a tack-free film. Uses: as coating compositions, sealants, impregnating compounds and for electrical insulation.
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