Polyurethane powder coatings containing polysiloxane

In this study, blocked polyisocyanate crosslinkers (PIC) for powder coatings were synthesized using isophorone diisocyanates (IPDI), formic acid, poly(dimethylsiloxane), epsilon-caprolactam, dibutyltin dilaurate as well as triethylamine as catalysts. The chemical structures of these compounds were confirmed by means of IR and NMR spectroscopy and the molecular weight distributions were investigated using gel permeation chromatography (GPC). Polyurethane powder coating systems consisting of polyester resin and synthesized polyisocyanate were examined. The surface structure of powder coatings was investigated with confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). The surface structure was correlated with the chemical structure of the coatings and macroscopic surface behavior: contact angle, surface free energy, gloss, abrasion and scratch resistance, hardness as well as adhesion to steel surface. (C) 2014 Elsevier B.V. All rights reserved.