Price: 10.00
Curing and imaging processes, based on photogeneration of acid, have not as yet achieved the commercial significance of corresponding free radical processes. Several reasons for this may be advanced including the development of photoinitiators for cationic polymerization was preceded
by substantial advances in curing and polymer imaging technology based on photoinitiated radical polymerization; the early developmental work on curing and imaging by cationic polymerization utilized aryldiazonium salts as photoinitiators which, while highly photoactive, are thermally unstable, thereby preventing long-term storage of fully-formulated compositions; and discoveries of thermally stable photoinitiators for cationic polymerization, initially diaryliodoniuin and triarylsulfonium salts, and, subsequently, mixed ligand arene, cyclopentadienyl ferrocenium salts, were made almost simultaneously by several industrial groups, which has resulted in unclear patent situations--a situation which appears to be resolved, at least with regard to the oniurn salts.
