Syntactic sealants

Claim 1

A syntactic sealant composition comprising a product obtained by mixing into a filled polyorganosiloxane sealant composition which is curable at room temperature, from 3 to 10 weight percent of ceramic microspheres having a true specific gravity of less than 1000 kg/m³, a bulk density of less than 500 kg/m³, and an average diameter of less than 500 micrometers and from 2 to 15 weight percent of an organic solvent which is compatible with the polyorganosiloxane sealant compositions and has a low volatility, where the weight percentages are based on the total weight of the syntactic sealant composition.

Claim 14

A method of making a syntactic sealant composition comprising mixing to homogeneity under anhydrous conditions a filled polyorganosiloxane sealant composition which is curable at room temperature into which is added from 3 to 10 weight percent of ceramic microspheres having a true specific gravity of less than 1000 kg/m³, a bulk density of less than 500 kg/m³, and an average diameter of less than 500 micrometers and from 2 to 15 weight percent of an organic solvent which is compatible with the polyorganosiloxane sealant compositions and has a low volatility, where the weight percentages are based on the total weight of the syntactic sealant composition and thereafter placing the homogeneously mixed composition into a container which will protect it from moisture.

Claim 15

A method of making a syntactic sealant composition comprising mixing to homogeneity under anhydrous conditions a filled polyorganosiloxane sealant composition which is curable at room temperature into which is added from 3 to 10 weight percent of ceramic microspheres having a true specific gravity of less than 1000 kg/m³, a bulk density of less than 500 kg/m³, and an average diameter of less than 500 micrometers and from 2 to 15 weight percent of an organic solvent which is compatible with the polyorganosiloxane sealant compositions and has a low volatility, where the weight percentages are based on the total weight of the syntactic sealant composition and thereafter placing the homogeneously mixed composition into a container which will protect it from moisture.

Claim 17

A method of making a syntactic sealant composition comprising mixing the contents of at least two containers where the resulting composition comprises the mixture of ingredients from a hydroxyl endblocked polydi­organosiloxane, a diorganodiamidosilane, an aminoxy silicon compound having from 1 to 100 silicon atoms per molecule and from 3 to 10 silicon-bonded aminoxy groups per molecule, at least 10 weight percent of a non-acidic, non-reinforcing filler based on the total weight of the composition, from 3 to 10 weight percent of ceramic microspheres having a true specific gravity of less than 1000 kg/m³, a bulk density of less than 500 kg/m³, and an average diameter of less than 500 micrometers, and from 2 to 15 weight percent of an organic solvent which is compatible with the polyorganosiloxane sealant compositions, has a low volatility, and is not an alcohol or a mercaptan, where the diorganodiamidosilane and the aminoxy silicon compound are in the same container optionally with a portion of the hydroxyl endblocked polydiorganosiloxane as long as these ingredients are present in amounts such that the number of diorganodiamidosilane molecules exceeds the number of hydroxyl groups.

Claim 18

A method of making a syntactic sealant composition comprising mixing the contents of at least two containers where the resulting composition comprises the mixture of ingredients from a hydroxyl endblocked polydi­organosiloxane, a diorganodiamidosilane, an aminoxy silicon compound having from 1 to 100 silicon atoms per molecule and from 3 to 10 silicon-bonded aminoxy groups per molecule, at least 10 weight percent of a non-acidic, non-reinforcing filler based on the total weight of the composition, from 3 to 10 weight percent of ceramic microspheres having a true specific gravity of less than 1000 kg/m³, a bulk density of less than 500 kg/m³, and an average diameter of less than 500 micrometers, and from 2 to 15 weight percent of an organic solvent which is compatible with the polyorganosiloxane sealant compositions, has a low volatility, and is not an alcohol or a mercaptan, where the diorganodiamidosilane and the aminoxy silicon compound are in the same container optionally with a portion of the hydroxyl endblocked polydiorganosiloxane as long as these ingredients are present in amounts such that the number of diorganodiamidosilane molecules exceeds the number of hydroxyl groups.