Dow Corning Corporation

Gary M Ronk

Chi-long Lee

Yung K Kim

Ronald E Kittle

A polydiorganosiloxane gum base stock can be foamed and cured by exposing to a microwave source a composition which comprises 100 parts by weight of the stock, 3 to 25 parts by weight of an organohydrogensiloxane, 0.05 to 0.5 part by weight of an acetylenic alcohol inhibitor, 1 to 200 p.p.m. platinum as a platinum catalyst and from 0.25 to 30 parts by weight of a microwave sensible material. This method is particularly useful where it would be impractical or undesirable to use heat to foam and cure silicone compositions.

Method of foaming a siloxane composition using microwave energy

Siloxane foams can be prepared by mixing an organohydrogensiloxane, a hydroxylated organosiloxane and a platinum catalyst in amounts such that the ratio of silicon-bonded hydrogen atoms to silicon-bonded hydroxyl radicals is from 2.5 to 7 and thereafter allowing the mixture to foam. The amount of open-cell structure in the foam can be increased by having present in the mixture an organomonohydrogensiloxane such that the molar ratio of silicon-bonded hydrogen atoms from the organohydrogensiloxane to silicon-bonded hydrogen atoms from the organomonohydrogensiloxane is from 0.4 to 2. The siloxane foams can be made to have an increased fire retardant property by adding 0.01 to 2 parts by weight carbon black based on the weight of the total composition. Siloxane foams are also prepared from mixing an organohydrogensiloxane, an organomonohydrogensiloxane, a hydroxylated organosiloxane, a vinyl containing triorganosiloxy endblocked polydiorganosiloxane and a platinum catalyst. These foams can be used for cushioning, in acoustical applications and protective filling or coating applications and especially applications wherein fire retarding is important.

Method of preparing fire retardant open-cell siloxane foams and foams

Siloxane foams which are activated and cured by heating can be prepared by mixing an organohydrogensiloxane, a hydroxylated organosiloxane and a rhodium catalyst in amounts such that the ratio of silicon-bonded hydrogen atoms to silicon-bonded hydroxyl radicals is from 2.5 to 40 and thereafter heating the mixture above 90.degree. C. The rhodium catalyst provided a pot life of at least 8 hours when used in amounts of 0.0025 grams per 100 grams of hydroxylated organosiloxane. The siloxane foams can be made to have an increased fire retardant property by adding 0.01 to 2 parts by weight carbon black based on the weight of the total composition. Siloxane foams are also prepared from mixing an organohydrogensiloxane, a hydroxylated organosiloxane, a vinyl containing triorganosiloxy endblocked polydiorganosiloxane and a rhodium catalyst. These foams can be used for cushioning, in acoustical applications and protective filling or coating applications and especially applications wherein fire retarding is important.

Method of preparing heat cured siloxane foams using rhodium catalyst and

Mixing a fluorinated surfactant with a silicone foam composition decreases the density of the cured foam. Increasing the amount of fluorinated surfactant decreases the foam density. Silicone compositions comprising a hydroxylated organosiloxane, an organohydrogensiloxane, a platinum catalyst and a fluorinated surfactant cure to foams with lower densities than the same compositions without the fluorinated surfactant. The cured foams can be used in the same applications as other silicone foams.

Method of reducing the foam density of silicone foams and compositions

Polydiorganosiloxane gum base stocks which contain per 100 parts by weight of the stock, 15 to 60 parts by weight of an organosiloxane having an average of at least 2 silicon-bonded hydroxyl radicals per molecule, 3 to 25 parts by weight of an organosiloxane having an average of at least 2.5 silicon-bonded hydrogen atoms per molecule, 0.05 to 0.5 parts by weight acetylenic alcohol inhibitor and 1 to 200 p.p.m. platinum as a platinum catalyst, can be sponged by heating the composition above 125.degree. C. The sponged products are elastomeric, have flame retardant properties and can be used where applications see relatively high temperatures.

Spongeable silicone gum stock

Mixing a hydroxyl endblocked polydiorganosiloxane, an organohydrogensiloxane, a platinum catalyst and a platinum catalyst inhibitor where the inhibitor is present in an amount of 0.0001 to 0.001 moles of inhibitor per 100 grams of hydroxyl endblocked polydiorganosiloxane and thereafter allowing the resulting mixture to cure, provides an elastomer.

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Midland, MI, United States of America

Gary M Ronk