Weather stabilization and pigmentation of UV-curable powder coatings

A UV-curable powder coating based on an unsaturated polyester binder and a vinyl ether crosslinker has been tested for weathering resistance. Accelerated and outdoor weathering demonstrate the combined protective action of a UV absorber and a hindered amine light stabilizer (HALS). Successful coatings cure of various colors and shades from organic and inorganic pigments is also reported in this study. Curing performance mainly depends on pigment absorption and particle size. A combination of a bis-acylphosphineoxide and an alpha-hydroxy-acetophenone photoinitiator overcomes limitations imposed by filtering of UV radiation by the pigments and provides balanced cure.