Rapid Curing System of a Cyanate Ester Resin/Epoxy Resin with a Thermal Latent Polymeric Hardener Based on a Phenol–Amine Salt

We studied the thermal behavior and curing process of a cyanate ester resin (Cy)/epoxy resin (EP)/thermal latent polymeric hardener system based on a phenol–amine salt (PA-hardener) and the resulting cross-linked structure. Additionally, the physical properties of the cured product were evaluated. As a result, the curing system of Cy/EP with the PA-hardener was found to have unique thermal behavior, and an adhesion process was conducted in which the functionality and reactivity of the cyanate ester resin were utilized. The system cured rapidly at approximately 80 °C and could be completely cured at 120 °C in 1 h because the PA-hardener dissolved in the resins at an elevated temperature to give free amines, which could readily initiate the polymerization of cyanate ester resins and epoxy resins. The glass-transition temperature (Tg) of the cured products increased with increasing a triazine-rich cross-linked structure derived from the cyclotrimerization of the cyanate ester resin as the curing proceeded at a relatively low temperature. The Cy/EP/PA-hardener system was found to have a rapid curing process and excellent adhesiveness, and it afforded a cured product with heat stability.