Dry-Water-System Confined Fabrication of Nanocuring Catalysts for Superior Low-Cure Powder Coating

Abstract

Curing catalysts can accelerate cross-linking reactions but often deteriorate surface performance due to heterogeneous catalysis, which can be resolved by improved homogeneous dispersion of nanoscale catalysts and thus uniform catalysis of resin cross-linking reaction. Nonetheless, nanosizing solidified catalysts, typically organic small molecular crystals, presents challenges using conventional top-down and bottom-up methodologies. Herein, we present a straightforward approach to preparing nanocuring catalysts by leveraging the dry-water structure and obtaining high-performance low-temperature curing coatings. The stable dry-water structure, with microscale catalyst solution droplets surrounded with hydrophobic fumed silica, was formed. Confinement of fumed silica effectively limits the size of the organic catalyst crystals on the nanoscale by ensuring the low 2-eim content in the separated compartment. Coatings incorporating the obtained catalyst, cured at a lower temperature of 170 °C for 15 min, exhibit mechanical strength and chemical resistance compared to standard powder coatings cured at 190 °C for 15 min. Furthermore, with the improved uniform catalysis brought from the nanocatalyst, the low-temperature curing coatings demonstrate excellent surface performance, maintaining gloss levels comparable to the original powder coating film. This study delves into the mechanism of the dry-water structure, offering a facile approach for fabricating nanoscale curing catalysts and achieving high-quality surfaces in powder coating applications.