Relationship between pigment properties and UV-curing efficiency

Due to solvent emission restrictions and rationalization in the coating industry, the UV-curing technology will play an important role in the future. One of the key success factors will be the feasibility to cure colored coatings without any major restrictions in terms of the pigments and their combination used. Colored substances are competing with their light absorption properties against the photoinitiators and the UV-absorbers. With the novel class of photoinitiators based on bis-acylphosphinoxides (BAPO), one step has been achieved to cure colored coatings effectively. But up to now there is a need that pigment manufacturers are doing research work to optimize their pigments for UV-curing efficiency. Preliminary investigations are reported herewith.