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Waterbased systems are commonly used in the coating industry because of environmental
concerns and they are becoming increasingly popular, even in a solvent-free technology Iike UVradiation curing. Indeed, by taking water to reduce the formulation viscosity one avoids the odor and irritation problems inherent to the use of acrylic reactive diluents. The potentialof waterbased systems and their overall performance in UV-radiation curing has not been investigated in depth so far 1-6. These systems consist generally of dispersions or emulsions of acrylate functionalized oligomers which are photocrosslinked in the solid state, after removal of the water. In comparison to conventional UV-curable resins, the advantages offered by these environmentally-friendly systems are' therefore partly offset by the necessity to introduce a drying step before the UVexposure, which will increase the overall processing time. The water sensitivity of these UV-cured polymers has to be evaluated since it may restrict their use in a humid environment and in exterior applications. The objective of the present work was to study the kinetics of both the drying stage and the highspeed UV-curing reaction, and to quantify the influence of the temperature on these two processes. Moreover, we have examined some of the physico-chemical properties of the· UVcured coatings. Urethane-acrylates have been selected as telechelic oligomers because of their overall balance of properties, in particular the superior resistance to abrasion and scratching, and the high impact and tensile strength of the cured polymer. As these compounds are not soluble in water, ionic groups had to be introduced into the polymer backbone to obtain a stabie dispersion.
