A New epoxy/episulfide resin system for coating applications: Curing Mechanism and Properties

A new epoxy/episulfide resin was applied using a polyamide(V-40®) curing agent system. The epoxy/episulfide/V-40® system exhibits much faster cure, better corrosion protection for copper, a lower thermal expansion coefficient and lower exotherm as compared with standard amine cure, room-temperature epoxy systems. From model compound studies, episulfide–amine, S−–epoxy, epoxy–amine reactions and episulfide homopolymerization proceed in the epoxy/episulfide system. The curing reactions are changed by changing the curing temperature and by the presence of copper. The episulfide homopolymerization and the S−–epoxy reaction increase in the case of room-temperature curing or in the presence of copper. The episulfide and/or the S− react with copper. From DSC measurements, the resin near the copper surface has higher Tg than the bulk resin due to the fact that the episulfide tends to polymerize near the copper surface.