Liquid methyl vinylphenylpolysiloxane resins

Claim 2

A liquid methylvinylphenylpolysiloxane resin comprising recurring units chosen from more than one of the formulae: CH 3 SiO 1 .5, (CH 3 ) 2 SiO, CH 3 (CH 2 =CH)SiO, CH 3 (C 6 H 5 )SiO, C 6 H 5 SiO 1 .5 and (C 6 H 5 ) 2 SiO, and corresponding to the average general formula: ##EQU5## in which Q represents an alkyl group with 1 to 4 carbon atoms, x and y, which may be identical or different, each represent a number from 0.55 to 0.85, z represents a number from 0.08 to 0.35, u represents a number from 0.08 to 0.3, and w represents a positive number which does not exceed 0.1, the sum x + y + z being from 1.5 to 1.9 and having a functional group content E of from 2.5 to 2.9.

Claim 3

A resin according to claim 1, wherein Q represents a methyl group, x and y each represent a number from 0.6 to 0.8, z represents a number from 0.1 to 0.3, u represents a number from 0.11 to 0.23, and w represents a positive number which does not exceed 0.07, the sum x + y + z being from 1.55 to 1.85, and the functional group content E is from 2.55 to 2.85.

Claim 4

Process for preparing a liquid methylvinylphenylpolysiloxane resin as defined in claim 1, which comprises the following steps, in sequence: a. cohydrolysing a mixture of chlorosilane chosen from more than one of those of the formulae CH 3 SiCl 3 , (CH 3 ) 2 SiCl 2 , CH 3 (CH 2 =CH)SiCl 2 , CH 3 (C 6 H 5 )SiCl 2 , C 6 H 5 SiCl 3 and (C 6 H 5 ) 2 SiCl 2 , the mixture being such that i. the number of methyl radicals, the number of phenyl radicals and the number of vinyl radicals per silicon atom in the mixture coincide with the specified values for x, y and z, respectively, ii. the sum of these numbers coincides with the specified values for the sum x + y + z, and iii. the functional group content E, calculated from these numbers is from 2.5 to 2.9; by contacting a solution of an organic diluent containing 20 to 50% by weight of the chlorosilane mixture at a temperature of from 5°C to 80°C, with an aqueous solution, of an alkanol with 1 to 4 carbon atoms, said solution providing for each gram atom of chlorine in the chlorosilane mixture at least 0.5 mol of alcohol and at least 0.3 mol of water; b. isolating the organic layer and treating it with at least one mol of water per mol of chlorosilane, at a temperature of from 10°C to 100°C, and c. isolating the organic layer again, removing the acid therefrom and distilling the organic diluent.

Claim 5

Process according to claim 3, wherein, in step (b), at least 2 mols of water are used per mol of chlorosilane.

Claim 6

Process according to claim 3, wherein the resin obtained is heated, in a medium comprising an organic diluent, with 0.005 to 0.5% by weight, relative to the resin, of an alkali metal hydroxide or quaternary ammonium or phosphonium hydroxide.

Claim 7

A composition comprising a liquid resin as defined in claim 1 and an organic peroxide in an amount of 0.5 to 5% by weight, based on the weight of the resin.

Claim 8

A composition comprising: 83 to 95% by weight of a liquid resin as defined in claim 1, wherein u represents a number from 0.08 to 0.2 and w represents a positive number which does not exceed 0.03, and 17 to 5% by weight, based on the weight of the composition, of a copolymerisable organic compound which possesses at least one aliphatic unsaturated bond.

Claim 9

A composition according to claim 7, wherein the copolymerisable organic compound is present in an amount of 15 to 6% by weight, based on the weight of the composition.

Claim 10

A composition according to claim 7, wherein the copolymerisable organic compound is selected from an ester of a saturated or unsaturated carboxylic acid and a glycol, or an unsaturated aliphatic alcohol an unsaturated ether of a polyol and an aromatic compound.

Claim 11

A composition according to claim 6, wherein the organic peroxide is present in an amount of 0.5 to 5% by weight, based on the weight of the composition.

Claim 12

A composition according to claim 6, wherein the organic peroxide is dicumyl peroxide, di-(tertiarybutyl) peroxide, tertiary butyl perbenzoate, benzoyl peroxide or 2,5-dimethyl-2,5-di(tertiarybutyl peroxy)-hexane.

Claim 13

A composition according to claim 6, which additionally comprises an organosilicon polymer possessing SiH bonds, and a platinum containing compound which is soluble or dispersible in the remainder of said composition in an amount of 0.0002 to 0.003% by weight based on the weight of platinum.

Claim 14

A composition according to claim 7 which additionally comprises an organosilicon polymer possessing SiH bonds, and a platinum-containing compound which is soluble or dispersible in the remainder of said composition in an amount of 0.0002 to 0.003% by weight based on the weight of platinum.

Claim 15

A method of protecting an electrically conducting material, which comprises applying thereto a composition as defined in claim 6 and curing the composition.

Claim 16

A method of protecting an electrically conducting material which comprises applying thereto a composition as defined in claim 12 and curing it by heating from 130° to 180°C. for at least 3 hours.