Silicone adhesive formulations
AssigneeDow Corning Corporation
InventorJohn D. Blizzard
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Abstract
Physical properties, especially tack characteristics, of silicone adhesives comprising a silicone polymer and a silicone resin are improved by incorporation, prior to curing, of certain silicone cluster compounds. One preferred cluster compound has the formula RSi{OSi(OR').sub.3 }.sub.3 wherein R is a methyl group and R' is a secondary butyl group.
Claims9
In a silicone pressure sensitive adhesive composition comprising 45 to 75 parts by weight of a silicone resin and 25 to 55 parts by weight of a silicone polymer gum, the improvement comprising adding to said composition 0.5 to 50 parts by weight, based on a total of 100 parts by weight of the resin and polymer gum, of a cluster compound selected from the group consisting of
- (A) RSi{OSi(OR').sub.3 }.sub.3,
- (B) M<OSi{OSi(OR').sub.3 }.sub.3 >.sub.a,
- (C) M<OSiR{OSi(OR').sub.3 }.sub.2 >.sub.a, and ##STR3## wherein R is hydrogen, an alkyl, alkenyl, aryl or aralkyl group,
- R' is hydrogen, an alkyl, alkenyl, aryl or aralkyl group with the proviso that at least a majority of the R' radicals are sterically hindered alkyl groups having at least 3carbon atoms,
- M is a substituted or unsubstituted branched or straight chain hydrocarbon radical,
- a is 2, 3, or 4,
- n is an integer from 0 to 300,
- R" is hydrogen, an alkyl, alkenyl, aryl, aralkyl or --OSi(OR').sub.3 group, and
- R''' is hydrogen, an alkyl, alkenyl, aryl, aralkyl, hydroalkyl, and halo or cyano substituted alkyl, alkenyl, aryl, aralkyl, and hydroalkyl.
Dependencies are inferred from the claim text.