High performance accelerated all acrylic coatings: Kinetics and mechanistic aspects of non-isocyanate coatings

Abstract

Non-isocyanate coatings continue to be among the most promising technologies used to meet environmental and safety concerns, as well as the performance requirements of the industrial coatings market. In general, the market demands the use of non-isocyanate, low VOC coatings without sacrificing the excellent durability associated with 2K urethane coatings. A novel approach to high performance, low VOC, non-isocyanate coatings has been developed. This approach is based on accelerated all acrylic (AAA) binders containing epoxy, tertiary-amine, and an in situ formation of acid (via anhydride and hydroxyl) groups. A model study to demonstrate the mechanism and kinetics of cure is presented. Three major cure reactions can lead to a highly cross-linked polymeric network. They include: (1) the reaction of anhydride and hydroxyl to generate the carboxyl group, (2) the quaternization of the tertiary-amine, and (3) the formation of oligomers. Coatings film properties have been correlated with the model study. Glycidyl-based epoxies are more reactive under basic conditions, while cycloaliphatic epoxies react more effectively under acidic conditions.