Dow Corning Corporation

Alan La Himstedt

Chana Wilson Evans

Judith Diane Baity

The present invention is a heat curable polyorganosiloxane composition comprising (A) a first polydiorganosiloxane having two diorganoalkenylsiloxy terminal groups per molecule and a total concentration of unsaturated hydrocarbon radicals of 0.118 to 0.156 mole percent; (B) a second polydiorganosiloxane having two diorganoalkenysiloxy terminal groups per molecule, and no detectable concentration of pendant unsaturated hydrocarbon radicals; (C) a third polydiorganosiloxane having two diorganoalkenysiloxy terminal groups per molecule and a total concentration of unsaturated hydrocarbon radicals of 1.37 to 2.24 mole percent; wherein the weight ratio of polydiorganoiloxanes (A), (B), and (C) satisfy the relationship (C)/(A+B)=0.0379 to 0.1071 and A/B=1.460 to 2.115; (D) a crosslinker containing silicone-hydrogen bonds, wherein the ratio of silicone-hydrogen bonds to the total ethylenically unsaturated hydrocarbon radicals present on the polydiorganosilanes (A), (B), and (C) is from 1.00 to 2.25; (E) from 5 to 50 weight percent of a silica filler; and (F) a catalytically effective amount of a platinum catalyst. Optionally, the composition may include an inhibitor.

High consistency platinum cure elastomer having improved physical

A silicone dispersion, having improved toughness and thixotropic characteristics, cures to an elastomer upon exposure to the air. The dispersion is particularly useful for spraying onto exposed electrical conductors to prevent their shorting out from contact with animals and birds. The dispersion contains a hydroxyl endblocked polydimethylsiloxane, aluminum trihydrate, moisture activated crosslinking agent and catalyst. In order to obtain thixotropy, it also contains a phenyl or 3,3,3 trifluoropropyl-containing hydroxyl endblocked polydiorganosiloxane and untreated fumed silica. The method of making the dispersion is also specified.

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Midland, MI, United States of America

Alan La Himstedt