Progress in development of UV curable powder coatings

Abstract

Powder coating systems are becoming more and more popular due to their unique properties. Nowadays, the ecological aspect is important and powder systems meet the following requirements. Powder systems do not contain VOC, they are more productive than liquid systems. Modifications of old powder systems and development of new ones stem from the need to replace liquid systems and extend the application of powder systems. UV-curable powder coatings present some new possibilities for the curing of heat sensitive substrates and offers more advantages compared to thermally cured powder coatings. UV-curing can be performed at lower temperatures than possible by thermally activated systems. This paper reviews the most recent advances in the field of ultraviolet cured powder coatings. The selected chemical structures of the resins (unsaturated polyester, urethane acrylates, acrylate and methacrylate resins, epoxy oligomers, polyamides and hyperbranched polymers) photoinitiators and additives used in formulation of UV-curable powder coatings were presented. The physical properties and rheological behavior of the resin depending on their chemical structure, molecular weight, amorphous and crystalline structure as well as their influence on properties of crosslinked coatings were described. The curing conditions used in UV curing technology and its advantages such as fast curing and high efficiency, low capital investment, solvent elimination, low cost and energy consumption were also presented.