Bonding durability against water of a fluorine-containing resin for precious metal alloys.

In order to clarify the effect of fluorination of an adhesive resin on the durability of the resin bond to precious metal alloys, 2,2,2-trifluoroethyl methacrylate (TFEMA)-poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA)/TBBO adhesive resin was prepared. The tensile bond strength of this resin to precious metal alloys treated with 9,10-epithiodecyl methacrylate (EP8MA) generally increased in the order Ag alloy<Pd alloy<Au alloy after thermal cycling; bond strength was decreased by thermal cycling. The water sorption of TFEMA-PTFEMA/TBBO resin was much higher than that of MMA-PMMA/TBBO resin because of phase separation. For Au alloy, the bonding durability of TFEMA-PTFEMA/TBBO resin against penetration of water was comparable to that of MMA-PMMA/TBBO resin; however, for Pd and Ag alloys the performance of the fluorinated resin was markedly inferior to that of MMA-PMMA/TBBO resin. These reduced tensile bond strengths were considered to be caused by insufficient copolymerization with EP8MA molecules adsorbed on the precious metal alloys.