The chemistry of new latent curing systems for epoxy resins

New types of catalyst combinations for epoxy resins are described and examples given. These combinations consist of a triethanolamine-chelated titanium compound or phosphorus compound and a borate ester which react to give triethanolamine borate and other epoxy-reactive products. The advantages of these addends as catalysts are ease of mixing with the resin, relatively long tank life (1 to 2 months), good electrical properties at elevated temperatures, and low viscosity where desired. Phosphorus compounds impart fire resistance. It is suggested that the composition of curing combinations of the type described may be varied over a wide range according to the properties desired for the resin–catalyst mixture and the final hardened resin.