Structure/properties relationships in photoinitiators of polymerization—9. The behaviour of a new bis α-sulphonyl ketone derivative

Abstract

The photochemistry of a new α-sulphonyl acetophenone characterized by high efficiency in the radical polymerization of acrylic coatings is presented. Its photochemical behaviour and the excited-state processes have been studied using time resolved laser spectroscopy and steady-state photolysis techniques; the photopolymerization activity has been evaluated. The photoinitiator works according to a β cleavage process in the triplet state (rate constant ⩽ 1.8 × 10 5 sec −1). Interactions with e.g. isopropanol, methylacrylate and methyldiethanolamine led to bimolecular quenching rate constants of 10 3, 7.4 × 10 5 and 3.2 × 10 8mol −1 sec −1, respectively. The main applications are UV curable inks and can be found in UV thin layer pigmented systems. One of its important peculiarities is the absence of odour developed after curing. Primary toxicological evaluations show its safety in handling.