Enhanced durability of exterior paints with light-stabiliser modified dispersants

 
The durability of an exterior paint is determined by numerous factors. Besides the stability of the binder, the pigment type and its light fastness play an important role. Certain pigment chemistries are known for their fast degradation upon weathering; especially sunlight exposure can cause rapid color fading. This paper describes the development of a new multifunctional pigment dispersant concept, in which light stabilizer moieties are chemically bound to the dispersant polymer. In addition to good pigment dispersant properties, such additives offer a remarkable light stabilizing effect on relevant pigment classes. Our fundamental studies confirm the theoretical model; the light stabilizer groups are positioned at the surface of the pigment particle via the adsorbed dispersant polymer. At this critical location they can very effectively prevent unwanted chemical degradation reactions of the pigment. Accelerated weathering studies and outdoor exposure results demonstrate how this novel concept can be an attractive formulation tool for improved color stability of organic pigments.