Moisture cured one-part RTV silicone sealant

Claim 1

A method of producing a one-part silicone sealant stable in the absence of moisture which cures on exposure to moisture having an in situ treated filler comprising (A) mixing (1) 100 parts by weight of a diorganovinylsiloxy endblocked polydiorganosiloxane where the viscosity of the siloxane is from 0.5 to 500 Pa.s at 25° C., (2) from 5 to 100 parts by weight of a reinforcing filler having a surface area of from about 50 to 400 m 2 /g, and (3) from 0.5 to 4.0 parts by weight of a silazane of the formula (RR"'MeSi) 2 NH, where R is methyl, ethyl, propyl, phenyl, or trifluoropropyl, R'" is methyl or vinyl, and where, if vinyl is present, the ratio of methyl to vinyl is from 1:1 to 50:1, for each 10 parts of filler (2), (B) heating the mixture to a temperature of 175° C., with a nitrogen, purge over the container to treat the filler, (C) cooling, then adding (4) sufficient silane of the formula H[SiR.sub.2 OSiR.sub.2 CH.sub.2 CH.sub.2 ].sub.b SiR.sub.a (OR").sub.3-a where R is methyl, ethyl, propyl, phenyl or trifluoropropyl, R" is methyl or ethyl, a is 0 or 1, and b is 0 or 1, to give a ratio of 1 to 3 mols of silane per mol of vinyl radical in polydiorganosiloxane (1), (5) from 1 to 50 parts by weight of platinum per million parts by weight of polydiorganosiloxane (1) as platinum catalyst, then heating for from 30 to 60 minutes at a temperature of from 65° C. to 125° C., then (D) applying a vacuum and cooling to room temperature, then (E) admixing in the absence of moisture, (6) from 3 to 15 parts by weight of a crosslinker of the formula R'.sub.a Si(OR").sub.4-a where R' is methyl or phenyl, R" is methyl or ethyl, and a is 0 or 1 and (7) from 0.2 to 2.0 parts by weight of a titanium catalyst, and (F) storing the mixture in the absence of moisture.

Claim 2

A method of producing a one-part silicone sealant stable in the absence of moisture which cures on exposure to moisture having an in situ treated filler comprising (A) mixing (1) 100 parts by weight of a diorganovinylsiloxy endblocked polydiorganosiloxane where the viscosity of the siloxane is from 0.5 to 500 Pa.s at 25° C., (2) from 5 to 100 parts by weight of a reinforcing filler having a surface area of from about 50 to 400 m 2 /g, and (3) from 0.5 to 4.0 parts by weight of a silazane of the formula (RR"'MeSi) 2 NH, where R is methyl, ethyl, propyl, phenyl, or trifluoropropyl, R'" is methyl or vinyl, and where, if vinyl is present, the ratio of methyl to vinyl is from 1:1 to 50:1, for each 10 parts of filler (2), (B) heating the mixture to a temperature of 175° C., with a nitrogen, purge over the container to treat the filler, (C) cooling, then adding (4) sufficient silane of the formula H[SiR.sub.2 OSiR.sub.2 CH.sub.2 CH.sub.2 ].sub.b SiR.sub.a (OR").sub.3-a where R is methyl, ethyl, propyl, phenyl or trifluoropropyl, R" is methyl or ethyl, a is 0 or 1, and b is 0 or 1, to give a ratio of 1 to 3 mols of silane per mol of vinyl radical in polydiorganosiloxane (1), (5) from 1 to 50 parts by weight of platinum per million parts by weight of polydiorganosiloxane (1) as platinum catalyst, then heating for from 30 to 60 minutes at a temperature of from 65° C. to 125° C., then (D) applying a vacuum and cooling to room temperature, then (E) admixing in the absence of moisture, (6) from 3 to 15 parts by weight of a crosslinker of the formula R'.sub.a Si(OR").sub.4-a where R' is methyl or phenyl, R" is methyl or ethyl, and a is 0 or 1 and (7) from 0.2 to 2.0 parts by weight of a titanium catalyst, and (F) storing the mixture in the absence of moisture.