Finely divided silicone rubber additive material and method for producing same

Claim 2

A finely divided additive material having a particle diameter of 1 mm or less and comprising a cured silicone rubber and a from 0.1 to 10 percent, based on the weight of said material, of a silane or partial hydrolysis product thereof, where said silane is represented by the general formula Y represents a terminally unsaturated alkenyl radical or a functional group bonded to the silicon atom of said silane by an alkylene radical, said functional group is selected from the group consisting of epoxy, amino, acryloxy, methacryloxy and mercapto, R¹ is a monovalent hydrocarbon radical, R² is a hydrogen atom or a monovalent hydrocarbon radical selected from the same group as R¹, and n is an integer from 0 to 2, inclusive, and where said silane or partial hydrolysis product thereof is present in the unreacted form or is chemically bonded to said silicone rubber.

Claim 3

An additive material according to claim 1 where the concentration of said silane is from 0.5 to 15 percent, based on the weight of said material, the cured silicone rubber is selected from the group consisting of organoperoxide-cured silicone rubber prepared by heating a diorganopolysiloxane containing at least one vinyl radical in the presence of an organoperoxide; silicone rubber prepared from a composition comprising a diorganopolysiloxane containing silicon-bonded vinyl groups, a diorganopolysiloxane containing silicon-bonded hydrogen atoms and a platinum compound; silicone rubber cured in the presence of an organotin compound or by a dehydrogenation/-condensation reaction between a diorganopolysiloxane having active hydrogen-containing functional group on both ends of the molecule and a diorganopolysiloxane having silicon-bonded hydrogen atoms; and silicone rubber cured by a condensation reaction between a diorganopolysiloxane having terminal hydroxyl groups and organosilane containing hydrolyzable groups in the presence of an organotin compound or a titanic acid ester.

Claim 4

In an improved method for producing a finely divided cured silicone rubber additive material having a particle diameter of 1 mm or less, said method comprising the sequential steps of I. dispersing as the discontinuous phase in water a curable silicon rubber composition comprising (A) a diorganopolysiloxane having at least 2 silicon-bonded hydroxy or 2 silicon-bonded alkenyl groups per molecule, (B) an organohydrogenpolysiloxane having at least 2 silicon-bonded hydrogen atoms per molecule, and (C) a curing catalyst in an amount sufficient to promote curing of said composition II. bringing the resultant dispersion or emulsion into contact with a gas or liquid having a temperature higher than that said water to cure said composition in the form of said finely divided additive having a particle diameter of up to 1 mm., the improvement comprising the presence in said curable silicone rubber composition of (D) a silane corresponding to the general formula where Y represents a terminally unsaturated alkenyl radical or a functional group bonded to the silicon atom of said organosilicon compound by an alkylene radical, said functional group is selected from the group consisting of epoxy, amino, acryloxy, methacryloxy and mercapto, R² represents a hydrocarbon radical selected from the same group as R¹, the value of n is from 0 to 2, inclusive, and said silane or hydrolysis product thereof is present either an unreacted form or chemically bonded within said particle.

Claim 5

In an improved method for producing a finely divided cured silicone rubber additive material having a particle diameter of 1 mm or less, said method comprising the sequential steps of I. dispersing as the discontinuous phase in water a curable silicon rubber composition comprising (A) a diorganopolysiloxane having at least 2 silicon-bonded hydroxy or 2 silicon-bonded alkenyl groups per molecule, (B) an organohydrogenpolysiloxane having at least 2 silicon-bonded hydrogen atoms per molecule, and (C) a curing catalyst in an amount sufficient to promote curing of said composition II. bringing the resultant dispersion or emulsion into contact with a gas or liquid having a temperature higher than that said water to cure said composition in the form of said finely divided additive having a particle diameter of up to 1 mm., the improvement comprising the presence in said curable silicone rubber composition of (D) a silane corresponding to the general formula where Y represents a terminally unsaturated alkenyl radical or a functional group bonded to the silicon atom of said organosilicon compound by an alkylene radical, said functional group is selected from the group consisting of epoxy, amino, acryloxy, methacryloxy and mercapto, R² represents a hydrocarbon radical selected from the same group as R¹, the value of n is from 0 to 2, inclusive, and said silane or hydrolysis product thereof is present either an unreacted form or chemically bonded within said particle.