By Nobuhiko Sakai, Kosuke Yanaba, Shigeaki Imazeki, FUJIFILM Wako Pure Chemical Corporation. Photoinitiators have been employed extensively in industry to initiate polymerisation in the fields of UV printing, coating, adhesion and photolithography because they produce initiators when irradiated. They can be roughly divided on the basis of their active species into: 1) free-radical-generating photoinitiators, 2) cationic photoinitiators, and 3) photobase generators. Free-radical and cationic photoinitiators have been the subject of a number of studies and are well known and often used in UV-curing systems. However, there are problems ...