Dow Corning Corporation

Lawrence D Fiedler

Chi-long Lee

Ronald H Baney

Carl J Bilgrien

Myron T Maxson

Gary T Burns

Roger G Chaffee

Diane M Rasch

A method of reducing the compression set of a silicone elastomer is accomplished by mixing an alkenyl silazane with a previously prepared, based heated, silanol-containing silicone elastomer base. Fluorosilicone elastomers prepared by these methods find use in gasketing and sealing application which are exposed to fuels and solvents.

Method to reduce compression set in silanol-containing silicone

The silacyclobutane functional polydiorganosiloxane copolymers of the invention have the following structure: ##STR1## wherein M is selected from ##STR2## wherein R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.e, and R.sup.f are independently monovalent radicals selected from the group consisting of hydrogen, hydrocarbon, or substituted hydrocarbon; m and x are integers of from 0 or more; n is equal to 1; and p is an integer greater than 0; with the proviso that there is at least one silacyclobutane group in the copolymer. The copolymer can be made by reacting a hydroxyl endblocked polydiorganosiloxane with either a difunctional chain extending silacyclobutane or with a monofunctional chain stopper, or a mixture of chain extender and chain stopper. The copolymer can be made into curable compositions by use of suitable catalyst.

Silacyclobutane functional polymers and their production

Novel silacyclobutanes useful as silylating agents and a process for their preparation are provided. The process comprises reacting a halogen substituted silacyclobutane with a silylating reagent to exchange the halogen substituents with groups on the silylating reagent. The novel compounds are of the formula ##STR1## wherein R' is a monovalent substituted or unsubstituted hydrocarbon radical or Y group; R' and R'' are independently hydrogen, monovalent substituent or unsubstituted hydrocarbon radical; and Y is selected from: ##STR2## and the disubstituted silacyclobutane wherein both Y and R' are ##STR3##

Silacyclobutanes

Novel silacyclobutanes useful as silylating agents and a process for their preparation are provided. The process comprises reacting a halogen substituted silacyclobutane with a silylating reagent to exchange the halogen substituents with groups on the silylating reagent. The novel compounds are of the formula ##STR1## wherein R' is a monovalent substituted or unsubstituted hydrocarbon radical or Y group; R' and R'' are independently hydrogen, monovalent substituted or unsubstituted hydrocarbon radical; and Y is selected from: ##STR2## and the disubstituted silacyclobutane wherein both Y and R' are ##STR3##

Process for preparation of silacyclobutanes

Polyorganosiloxane gels exhibiting a resistance to discoloration, hardening and surface deformation at temperatures of 100.degree. C. and above can be prepared by curing compositions comprising a polydiorganosiloxane containing silicon bonded fluorinated hydrocarbon radicals and an organohydrogensiloxane containing at least three silicon bonded hydrogen atoms per molecule in the presence of a platinum containing catalyst and up to 0.1 percent, based on the weight of said composition, of copper acetylacetonate.

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Midland, MI, United States of America

Lawrence D Fiedler