Dow Corning Corporation

Russell P Kamis

Loren D Lower

Jerome M Klosowski

Hsien-Kun Chu

John E Dietlein

A process for producing a silicone sealant, which is stable in the absence of moisture, cures when exposed to moisture, has an elongation at break of greater than 800 percent, and has adhesion to concrete. The silicon sealant is produced by first mixing an alkoxysilethylene endblocked polymer, a dialkyldialkoxysilane, and a titanium catalyst, then mixing in precipitated calcium carbonate filler having a fatty acid surface treatment.

Low modulus silicone sealants

A moisture curing silicone sealant which adheres to a variety of substrates is produced by a method which first mixes a trialkoxysilethylene endblocked polydiorganosiloxane, a trialkoxysilane crosslinker, and a beta-dicarbonyl titanium catalyst, then adds a precipitated calcium carbonate filler having a fatty acid treated surface.

Adhesion of silicone sealants

A silicone composition which is stable in the absence of moisture, but cures to an elastomer upon exposure to moisture consists essentially of a hydroxyl endblocked polydiorganosiloxane; a difunctionalsilane having acetamido, urea, or urethane functional groups; and a tetrafunctionalsilane having oximino functional groups. A composition containing 100 parts by weight of the polydiorganosiloxane, from 0.1 to 7 parts by weight of difunctionalsilane, from 0.1 to 7 parts by weight of tetrafunctionalsilane, and a ratio of difunctionalsilane to tetrafunctionalsilane of from 0.1 to 3, and optional filler is useful as a sealant or adhesive, having an improved skin over time.

Silicone sealants

A chelated titanium catalyst can be improved by the addition of an additive selected from the group consisting of organomercaptan of the formula RSH, where R is a hydrocarbon radical containing from 3 to 12 carbon atoms, and mercapto containing silane of the formula HSR'SiX.sub.3, where R' is a divalent hydrocarbon having from 1 to 8 carbon atoms and X is alkoxy radical having 1 to 6 carbon atoms. The improved composition has a reduced tendency to develop color upon storage. The improved composition is particularly useful in a silicone composition comprising a hydroxyl endblocked polydiorganosiloxane and an alkoxysilane or mixture of alkoxysilanes, or in a silicone composition comprising an alkoxy endblocked polydiorganosiloxane.

Silicone sealants having reduced color

A faster curing neutral curing composition is obtained by the additive of an oxime compound to a composition comprising a trialkoxysilethylene endblocked polydiorganosiloxane, alkoxysilane crosslinker, and titanium catalyst.

Neutral cure silicone sealants

A silicone sealant which is stable in the absence of moisture and cures upon exposure to moisture to give an elastomer with a controllable modulus is produced by mixing a polydiorganosiloxane having both vinyl and alkoxysilethylene endblocking, alkoxy silane crosslinker, titanium catalyst, and optional filler. The modulus is controlled by varying the ratio of vinyl to alkoxysilethylene endblocking present on the polymer.

Modulus control in silicone sealant

A process for producing a silicone sealant which is stable in the absence of moisture and having a slump of less than 1 inch mixes a polydiorganosiloxane polymer having hydroxyl or alkoxysilethylene endblocking, an alkoxysilane crosslinker, and a titanium catalyst; then adds a reinforcing filler.

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Midland, MI, United States of America

Russell P Kamis