Photoinitiators with functional groups .4. Water-soluble photoinitiators containing quaternary ammonium groups

The syntheses and properties of a series of new water-soluble hydroxyalkylphenone-based photoinitiators (PIs) for UV curing of waterborne systems is described. By reaction of tosyl- (2), chloro- (3), and dimethylamino- (4) derivatives of the commercially available PI 2-hydroxy-1-[4-(2-hydroxy-ethoxy)phenyl]-2 (1, Darocur 2959) with tertiary amines and halogenides, respectively, PIs containing quaternary ammonium groups exhibiting high water solubility were obtained. Preliminary photocalorimetric tests of the activity demonstrated excellent efficiencies for the PIs in a commercial water-based acrylate formulation, exceeding the photoactivity of the reference PT (1) substantially.