New developments in weather resistant powder coatings

A disadvantage found when conventional weather resistant powder coatings are compared to liquid coatings is their relatively poor flow properties. The flow of thermoset powder coatings depends on a number of factors, including the selection of suitable pigments and fillers, pigment concentration, additives such as flow agents, bake schedule, reactivity and structure of the resinous components, melt viscosity, and the viscosity profile during crosslinking. This paper reports about recently developed carboxyl terminated triglycidyl isocyanurate (TGIC) cured polyesters which result in powder coatings with remarkably improved flow properties due to the polyester's molecular structure and functionality and the viscosity profile during the curing process. These improvements have been reached without any prolongation of the gel time and without compromising the weathering resistance of the film. Such new powder coatings completely crosslink at 160°C within 15 minutes yielding films with excellent mechanical properties.