Development of imidazole-based latent curing agent via mechanochemical encapsulation

Abstract

One-part epoxy is a form where resin and curing agent are pre-mixed, and it is widely used in various fields such as electronic packages, adhesives, coatings, solders, resist inks, and composites due to its convenience and consistent performance. However, one-part epoxy easily reacts during storage due to the reactivity of curing agent, which necessitates providing long-term stability, i.e., latent properties. Current methods for enhancing long-term stability are mostly rely on wet processes, showing economically- and environmentally-unfriendly issues.

Herein, unlike conventional wet processes, latent curing agents were developed through a dry encapsulation process. In the 1st step, imidazole was transformed into an adduct through a chemical reaction, and in the 2nd step, a dry encapsulation process coated the silica/urea layer. The synthesized latent curing agent was evaluated for its physical/thermal/mechanical properties using FT-IR, NMR, SEM, DSC, TGA, UTM, and viscometer.