Decorative powder coatings

Abstract

Water-borne paints are widespread in the coatings industry. Their degree of penetration in the higher performance decorative paint segments (like in high gloss paints, trim paints and also in stains and varnishes) is relatively low. Professional painters still perceive the performance and application properties, specifically the open time, rheology, film build and scratch resistance of solvent-based alkyd paints superior to water-borne paints. Over the years, the improvement of the open time has been an intense area of research, but to date the typical paint rheology and brushing performance of a solvent-based paint could not be achieved in a water-borne system. This paper describes a new route to achieve prolonged open time and wet edge time in a water-borne paint. Very low viscosity oligomers are presented, that remain liquid even after the evaporation of water. These oligomers are self-crosslinking to achieve good final properties. The oligomers are combined with a dispersed polymer to reduce tack free times of the resulting coatings and to increase the rate of development of the properties. A model system is described where this effect is demonstrated. On balance, this new technology is providing an excellent alternative for the currently used solvent-based alkyds.