Low temperature vulcanizing carborane siloxane adhesive
AssigneeHughes Aircraft Company
InventorThomas K. Dougherty
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Abstract
A carborane siloxane base polymer is formulated into a crosslinked, rubbery high temperature material by incorporating a vinyl group in the backbone of the polymer. By careful control of process variables, the crosslinked polymer allows formation of optically clear and thermally stable adhesive bonds between a number of substrates. While curing is conveniently done at ambient temperature, the adhesive can withstand thermal cycling to over 600.degree. C.
Claims16
A low temperature vulcanizing carborane siloxane adhesive composition comprising (a) a polycarborane siloxane polymer having a number average molecular weight in excess of 120,000 and having vinyl groups attached to the backbone thereof, the concentration of vinyl groups per carborane group ranging from about 3 to 30%, (b) a curing agent comprising two terminal --SiH groups, and (c) a hydrosilation catalyst comprising a transition metal complex.
A method of preparing a low temperature vulcanizing carborane siloxane adhesive comprising:
- mixing a mixture comprising (i) a very high molecular weight polycarborane siloxane polymer having a number average molecular weight in excess of 120,000 and having vinyl groups attached to the backbone thereof, (ii) a curing agent comprising two terminal --SiH groups and having a --SiH group molar ratio slightly less than the number of vinyl groups in said polymer, and (iii) a catalyst for promoting the reaction between said polymer and said curing agent.
Dependencies are inferred from the claim text.