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

Abstract

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.