Electrostatic fluidized bed (EFB) coating of heat sensitive and electrical insulating substrates with low-curing thermoset epoxy-polyester (EP) powders

In this study, the electrostatic fluidized bed (EFB) coating process of heat sensitive and electrical insulating substrates with low-curing thermoset epoxy-polyester (EP) powders is researched. A relatively novel prepaint treatment, based on a peening process of plastic substrates with copper powders and performed inside an abrasive fluidized bed (AFB), is developed and analyzed. The influence of EFB coating process parameters, that is, coating time, voltage and flow rate, on the resulting polymeric films has been investigated in terms of coating thickness and average roughness. Subsequently, the location of part to be coated in the bed is studied. In particular, the influence on coating thickness of part attitude, radial location, dip distance and time has been considered. Finally, the curing kinetic of EP powders has been worked out and, therefore, the analysis of baking temperature able to produce the best curing condition of the polymeric films has been led, with particular regard to the estimation of film properties, that is, coating thickness and surface finishing as well as scratch adhesion and gloss. (C) 2006 Published by Elsevier B.V.