Oil resistant low modulus silicone sealant composition

Claim 1

A low modulus, one component, room temperature, vulcanizable silicone rubber composition consisting essentially of: from about 25 to about 90 percent by weight based upon the total weight of the composition of a devolatilized silanol/terminated diorganosiloxane base polymer having a viscosity from about 2,000 to about 250,000 centipoises at 25° C. where said organo groups can be the same or different and are selected from the groups consisting of alkyl having from 1 to 8 carbon atoms, a cycloalkyl having from 4 to 7 carbon atoms, an alkenyl having from 2 to 8 carbon atoms, an aryl or an alkyl substituted aryl having from 6 to 14 carbon atoms, or a fluoroalkyl having from 1 to 8 carbon atoms; from about 0 to about 40 percent by weight based upon the total weight of said composition of a plasticizer comprising a devolatilized diorganopolysiloxane fluid plasticizer terminated with triorganosiloxy groups, said organo groups being a monovalent hydrocarbon radical as set forth above with regard to said base polymer, said plasticizer having a viscosity from about 50 to about 100,00 centipoises at 25° C.; from about 2 to about 15 percent by weight based upon the total weight of said composition of an oxime crosslinking agent of the formula ##STR4## where y is 2.2 to 3, x is 0.8 to 1.0, where R 3 is selected from the group consisting of an alkyl having from 1 to 8 carbon atoms, an alkenyl having from 2 to 8 carbon atoms, a haloalkyl having from 1 to 8 carbon atoms, and a haloalkenyl having from 2 to 8 carbon atoms, where A and B can be the same or different and wherein A and B are selected from the group consisting of a hydrogen, an alkyl having from 1 to 8 carbon atoms, a haloalkyl having from 1 to 8 carbon atoms, a cycloalkyl having from 4 to 7 carbon atoms, an alkenyl having from 2 to 8 carbon atoms, and a cycloalkenyl having from 4 to 7 carbon atoms; from about 0.01 to about 0.5 percent by weight based upon the total weight of said composition of an organo tin catalyst and; from about 5 to 60 percent by weight based upon the total weight of said composition of a hydrophobic calcium carbonate filler having 0.4 percent or less water content therein when the amount of said filler is 15 percent or less, or 0.2 percent or less water content when the amount of said filler ranges from about 15 to about 60 percent by weight.