Polydiorganosiloxane latex

Claim 1

A method of producing an aqueous latex of crosslinked polydiorganosiloxane consisting essentially of (A) homogenizing immediately after admixing, a mixture consisting essentially of (1) 100 parts by weight of polydiorganosiloxane of the formula HO(R.sub.2 SiO).sub.x H wherein each R is a radical selected from the group consisting of methyl, ethyl, propyl, phenyl, vinyl, allyl, and 3,3,3-trifluoropropyl, and x is an average value in the range of from 3 to 100 inclusive, (2) 0.5 to 15 parts by weight of an alkoxy silicon compound selected from the group consisting of a silane of the formula R.sub.a 'Si(OR.sup.3).sub.4-a where R' is a monovalent hydrocarbon radical having up to 12 carbon atoms, R 3 is an alkyl radical having from 1 to 6 inclusive carbon atoms, and a is 0 or 1; a partial hydrolyzate of the silane where the partial hydrolyzate is soluble in the polydiorganosiloxane (1); and mixtures of silane and partial hydrolyzate, (3) from 20 to 100 millimoles of surface active anionic catalyst per kilogram of polydiorganosiloxane, where said catalyst is selected from the group consisting of a compound of the formula R 2 C 6 H 4 SO 3 H wherein R 2 is a monovalent hydrocarbon radical of at least 6 carbon atoms; a compound of the formula R 2 OSO 2 OH wherein R 2 is as defined above; a compound of the formula ##STR7## wherein R 2 is as defined above and R 4 is hydrogen or R 2 ; and mixtures thereof, and (4) water, to yield an oil-in-water emulsion, then (B) maintaining the emulsion produced in (A) at a temperature of from 15° to 30° C. for at least 5 hours at a pH of less than 5 until a crosslinked polymer emulsion is formed, then (C) admixing sufficient base to raise the pH of the product of (B) to greater than 7, then (D) admixing greater than 1 part by weight of colloidal silica or colloidal silsesquioxane to yield a latex which produces an elastomer upon removal of the water at room temperature.

Claim 2

A method of producing an aqueous latex of crosslinked polydiorganosiloxane consisting essentially of (A) homogenizing immediately after admixing, a mixture consisting essentially of (1) 100 parts by weight of polydiorganosiloxane of the formula HO(R.sub.2 SiO).sub.x H wherein each R is a radical selected from the group consisting of methyl, ethyl, propyl, phenyl, vinyl, allyl, and 3,3,3-trifluoropropyl, and x is an average value in the range of from 3 to 100 inclusive, (2) 0.5 to 15 parts by weight of an alkoxy silicon compound selected from the group consisting of a silane of the formula R.sub.a 'Si(OR.sup.3).sub.4-a where R' is a monovalent hydrocarbon radical having up to 12 carbon atoms, R 3 is an alkyl radical having from 1 to 6 inclusive carbon atoms, and a is 0 or 1; a partial hydrolyzate of the silane where the partial hydrolyzate is soluble in the polydiorganosiloxane (1); and mixtures of silane and partial hydrolyzate, (3) from 20 to 100 millimoles of surface active anionic catalyst per kilogram of polydiorganosiloxane, where said catalyst is selected from the group consisting of a compound of the formula R 2 C 6 H 4 SO 3 H wherein R 2 is a monovalent hydrocarbon radical of at least 6 carbon atoms; a compound of the formula R 2 OSO 2 OH wherein R 2 is as defined above; a compound of the formula ##STR7## wherein R 2 is as defined above and R 4 is hydrogen or R 2 ; and mixtures thereof, and (4) water, to yield an oil-in-water emulsion, then (B) maintaining the emulsion produced in (A) at a temperature of from 15° to 30° C. for at least 5 hours at a pH of less than 5 until a crosslinked polymer emulsion is formed, then (C) admixing sufficient base to raise the pH of the product of (B) to greater than 7, then (D) admixing greater than 1 part by weight of colloidal silica or colloidal silsesquioxane to yield a latex which produces an elastomer upon removal of the water at room temperature.