The Scratch Resistance of Radiation curable coatings for Automotive Applications

Since the reduction of VOC is a main issue, radiation-cured coatings have quite recently entered the automotive market, with specific applications on plastic and metallic parts, in replacement of classical solvent based coatings. The article is dedicated to the scratch resistance of UV-cured clearcoats. The scratch resistance has been assessed by means of both the Taber test and a microscratch test coupled with scanning stylus profilometry. The visual criteria for evaluation of the scratch resistance is found to give no idea of the actual damage type that the coating has undergone. This is why we also used a fracture criterion in order to rank our formulations. Relationships with other physico-chemical properties such as the adhesion to the substrate, the indentation depth, the indentation hardness and the viscoelastic properties have been investigated as well. Recommendations are provided in order to optimize the scratch resistance of coatings dedicated to automotive applications.