Surface Chemical Methods to Investigate Film Formation of Powder Coatings

摘要

All flow additives that were investigated have no influence on the viscosity of a typical powder coating binder (epoxy resin). However, they have a large influence on surface tension; already small concentrations lead to a tremendous decrease. While distinctly modified polyacrylates differ only slightly in their ability to reduce the surface tension, for polysiloxanes a strong dependence on their molecular structure was observed. At higher concentrations (1 weight-%) polyacrylates accumulate as patches on the binder surface, whereas polysiloxanes do not show such behaviour. This may be explained by differences in the behaviour of the two sorts of the tested additives due to compatibility and miscibility with the binder melt.