Barbara Pilch-Pitera, Department of Polymer Science, Rzeszów University of Technology, synthesised blocked polyisocyanate crosslinkers (PIC) for powder coatings using isophorone diisocyanates (IPDI), formic acid, poly(dimethylsiloxane), ɛ-caprolactam, dibutyltin dilaurate as well as triethylamine as catalysts.

 

Polysiloxane resulted in better properties

 

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 synthesised 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 behaviour: contact angle, surface free energy, gloss, abrasion and scratch resistance, hardness as well as adhesion to steel surface. The best properties were observed in coatings with polysiloxane content at 1%.