Conductive polyurethane-based powder clear coatings modified with carbon nanotubes

•Two methods of the modification of PU powder clear coatings by means of MWCNTs was proposed.•The good dispersion of MWCNTs in powder coatings was confirmed by TEM microscopy.•An improvement in the electrical conductivity and corrosion resistance of modified coatings was observed. In this work, two dispersing methods of multiwalled carbon nanotubes (MWCNTs) in polyurethane powder clear coatings based on a polyester resin and a blocked polyisocyanate were developed. TEM micrographs confirmed that additional sonication of MWCNTs in the polyester resin (before extrusion of the coatings) causes significantly better dispersion of the nanofiller in a polyurethane matrix in relation to a simple prepared without the sonification stage. Several properties of cured coatings were investigated such as roughness, gloss, adhesion to steel surface, cupping, hardness, scratch resistance, water contact angle, surface resistivity and corrosion resistance. The obtained results indicated that the water contact angle, electrical conductivity and the corrosion resistance of the PU coating were increased by the MWCNTs addition.