RADICALIC PHOTOINITIATORS IN UV-CURING

Photopolymerization science has become an increasing interesting subject because of its widespread applications. In the development of this technology, photoinitiator systems play a very important role. Absorption of light radiation of the appropriate wavelenght by a photoinitiator lead to the formation of primary radical species able to convert a multifunctional monomer into a crosslinked network. The performance of the photoinitiation system is related to high absorptivity, high efficiency in terms of both quantum yield for radical formation and high reactivity towards the monomer, low odor and toxicity and good storage stability. Photoinitiated radical polymerization may be in itiated by both cleavage (type I) and Habstracting (type II) initiators. In this survey, Type I and type II initiator systems were investigated and additionaly recently developed one-component thioxanthone based photoinitiators were reported.