COPOLYMERIC SYSTEMS BEARING SIDE-CHAIN THIOXANTHONE AND ALPHA-AMINOACETOPHENONE MOIETIES AS PHOTOINITIATORS FOR ULTRAVIOLET-CURABLE PIGMENTED COATINGS

Copolymers of ophenyl)-2-benzyl-2-[N-methyl-N-(3-methacryloyloxy propy l)]aminopropan-1-one and of ethyl-N-(3-methacryloyloxypropyl)]aminobut an-1-one with 1-[(2-methacryloyloxy)ethoxycarbonyl]thioxanthone were p repared and structurally characterized. The above systems were also ch ecked in the ultraviolet cure of an acrylic mixture upon irradiation o ver 380 nm, thus simulating the conditions of a TiO2-pigmented formula tion. The curing results were compared with those obtained in the pres ence of the mixtures of the corresponding homopolymers as well a; of t heir low-molecular-weight models. The copolymeric systems display syne rgistic effects of activity with respect to the structural models but show lower photoinitiation efficiency against the homopolymers mixture s. These data are discussed and interpreted in terms of structural req uirements and photochemical mechanistic aspects of the above systems. (C) 1997 John Wiley & Sons, Inc.