Effects of IR pre-curing conditions on wear resistance of metal flake powder coatings

Hybrid IR/convective oven baking of high quality industrial powder coatings is one of the most attractive method to achieve significant economic and process time savings. This method is based on two curing steps: at first, a pigmented decorative basecoat is electrostatically sprayed and, then, pre-cured with IR-radiation, secondly, a transparent protective topcoat is sprayed on the basecoat and the resulting bilayer coating is oven baked. The optimization of the IR pre-curing conditions and the correlation between the effect of polymerization degree of the basecoat and the wear resistance of the whole coating system are investigated. In particular, an experimental study in which the degree of chemical conversion of the pigmented basecoat, the overall coating morphology and its thermal, mechanical and tribological properties are analyzed in the light of IR-radiation time and power, has been carried out. Experimental results show that the intermediate range of curing time and IR power investigated leads to properly cured basecoats and subsequently to better morphological, mechanical and tribological behavior of the whole coating system. These results were also validated by comparison with the coatings cross-linked by the traditional two-step oven baking process. (C) 2010 Elsevier B.V. All rights reserved.