Abstract: Organopolysiloxane compositions which cure by the addition reaction of silicon-bonded lower alkenyl radicals with silicon-bonded hydrogen atoms and which exhibit improved adhesion to a variety of substrates. The compositions comprise an adhesion promoting mixture comprising an epoxy-functional compound, a compound having at least one hydroxy group and in the same molecule at least one substituent selected from a group consisting of silicon hydride, alkenyl, and acryl, and an aluminum compound or zirconium compound. Compression set of the cured organopolysiloxane compositions is not significantly effected by the adhesion promoting mixture.

Abstract: A composition curable to a silicone rubber exhibits adhesion to metal and glass substrates under both dry and wet conditions where the composition contains an alkenyl-containing polydiorganosiloxane, an organohydrogensiloxane, a hydrosilation catalyst containing platinum, an (epoxy-functional organo)trialkoxysilane, an alkoxy-silicon compound, and a titanium compound having Ti--O--CH bonds and the molar amount of alkoxy-silicon compound exceeds the molar amount of (epoxyfunctional organo)trialkoxysilane.

Abstract: Liquid silicone compositions are described that cure to rubber which exhibits a unique combination of properties including low compression set and unprimed adhesion to a variety of substrates. The compositions include silicone polymers curable by hydrosilation reaction and specific combinations of adhesion promoting materials. Compositions containing aluminum chelates and epoxytrialkoxysilanes have been found particularly useful when adhesion to metal substrates is desired. When the compositions are desired to adhere to plastic materials, it is advantageous to include along with the aluminum chelate and epoxytrialkoxysilane, a tetraalkyltitanate, an alkylpolysilicate, and an acrylate or methacrylate compound.

Abstract: The tear strength of cured organosiloxane elastomers can be increased and the compression set value reduced without adversely affecting other physical properties if the composition used to prepare the elastomer is curable by a platinum-catalyzed hydrosilation reaction and contains a mixture of two liquid diorganoalkenylsiloxy terminated polydiorganosiloxanes, one of which constitutes from 96 to 99.5 percent by weight of said mixture and contains the alkenyl radicals only at the terminal positions. The second polydiorganosiloxane contains both terminal alkenyl radicals and from 1 to 5 mole percent of alkenyl radicals on non-terminal repeating units.