Method of reducing the bubble formation when curing a room temperature vulcanizable silicone sealant composition with silicon-bonded alkoxy crosslinker on a hot porous surface
AssigneeDow Corning Corporation
InventorsLawrence D. Carbary, Jerome M. Klosowski
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Abstract
Bubble formation observed when curing a sealant composition on a hot porous substrate is reduced where the room temperature vulcanizable silicone sealant composition comprises a polydiorganosiloxane, a crosslinker with silicon-bonded alkoxy groups, filler, and a titanium catalyst by the addition of 0.5 to 2 weight percent of an oximosilicon compound.
Claims12
A method of bonding silicone sealant to a hot porous substrate at a temperature of at least 40.degree. C. comprising
- (I) adding from 0.5 to 2 inclusive weight percent based on the total weight of a room temperature vulcanizable silicone sealant composition of an oximosilicon compound which is an oximosilane or a mixture of oximosilanes and which has a general formula R.sub.x Si(Ox).sub.y (OR').sub.z in which R is methyl, ethyl, vinyl, or phenyl, R' is methyl or ethyl, Ox is ethylmethylketoximo, x has an average value of from 0 to 2 inclusive, y has an average value of from 2 to 4 inclusive, z has an average value of from 0 to 2 inclusive, the sum of x, y, and z is 4, and the mixture of oximosilanes have at least 80% of the silane molecules with 2 or more ethylmethylketoximo groups per molecule, to a prepared room temperature vulcanizable silicone sealant composition comprising a polydiorganosiloxane having condensable endgroups, an alkoxysilane crosslinker having at least three silicon-bonded alkoxy groups per molecule in an amount of from 1 to 10 weight percent based on the total weight of the room temperature vulcanizable silicone sealant composition, a filler, and a titanium catalyst for promoting room temperature cure of the silicone sealant composition,
- (II) contacting a surface of a hot porous substrate at a temperature of at least 40.degree. C. with the product obtained from (I),
- (III) exposing the product of (II) to atmospheric conditions allowing the product of (I) to cure to a silicone sealant, thereby obtaining a silicone sealant bonded to a surface of the hot porous substrate.
In a method of curing a room temperature vulcanizable silicone sealant composition in contact with a hot porous surface at a temperature of at least 40.degree. C. where the silicone sealant comprises a polydiorganosiloxane having condensable endgroups, an alkoxysilane crosslinker having at least three silicon-bonded alkoxy groups per molecule in an amount of from 1 to 10 weight percent based on the total weight of the room temperature vulcanizable silicone sealant composition, a filler, and a titanium catalyst for promoting room temperature cure of the silicone sealant composition, the improvement consists essentially of adding to the prepared silicone sealant composition from 0.5 to 2 inclusive weight percent based on the total weight of the silicone sealant of an oximosilicon compound which is an oximosilane or a mixture of oximosilanes and which has a general formula R.sub.x Si(Ox).sub.y (OR').sub.z in which R is methyl, ethyl, vinyl, or phenyl, R' is methyl or ethyl, Ox is ethylmethylketoximo, x has an average value of from 0 to 2 inclusive, y has an average value of from 2 to 4 inclusive, z has an average value of from 0 to 2 inclusive, the sum of x, y, and z is 4, and the mixture of oximosilanes have at least 80% of the silane molecules with 2 or more ethylmethylketoximo groups per molecule.
A method comprising
- (I) admixing from 0.5 to 2 inclusive weight percent based on the total weight of a room temperature vulcanizable silicone sealant composition of an oximosilicon compound which is an oximosilane or a mixture of oximosilanes and which oximosilicon compound has a general formula R.sub.x Si(Ox).sub.y (OR').sub.z in which R is methyl, ethyl, vinyl, or phenyl, R' is methyl or ethyl, Ox is ethylmethylketoximo, x has an average value of from 0 to 2 inclusive, y has an average value of from 2 to 4 inclusive, z has an average value of from 0 to 2 inclusive, the sum of x, y, and z is 4, and the mixture of oximosilanes have at least 80% of the silane molecules with 2 or more ethylmethylketoximo groups per molecule, to a prepared room temperature vulcanizable silicone sealant composition comprising a polydiorganosiloxane having condensable endgroups, an alkoxysilane crosslinker having per molecule at least three silicon-bonded alkoxy groups having 1 to 2 carbon atoms per alkoxy group in an amount of from 1 to 10 weight percent based on the total weight of the room temperature vulcanizable silicone sealant composition, a filler, and a titanium catalyst for promoting room temperature cure of the silicone sealant composition,
- (II) bringing the product of (I) into contact with a surface of a porous substrate which is at a temperature of at least 40.degree. C.,
- (III) exposing the product of (II) to atmospheric conditions allowing the product of (I) to cure to a silicone sealant, thereby obtaining a silicone sealant bonded to a hot porous substrate.
Dependencies are inferred from the claim text.