Importance Of Surface Tension For Radiation Curable Coatings Properties

UV-cured coatings are extensively used and the variety of substrates on which they can be applied is growing up. A good knowledge of the wetting characteristics of these substrates is necessary to
achieve properties such as coating adhesion, printing, pigment dispersion and cleaning. The wetting behaviour is controlled by the surface tension of both the liquid and the substrate. Consequently, surface tension measurement is the key tool to understand the applicative properties of the coating and to solve different problems that can arise during its life time.

In this article, a comparison between two methods commonly used to measure surface tension of
liquids is made : Du Nouy Ring method and pending drop method. In order to compare the surface tension of oligomers that show differences in viscosity, the influence of temperature has been studied. Since the properties of the substrate govern the final properties of the cured coating, the measure of surface tensions of solids has also been studied.
Finally, examples of applications of surface tension are presented to better understand problems of adhesion.