Enhanced scratch resistance in automotive clear coatings
Researchers have described an enhanced wear resistance in automotive clear coatings by modifying a crosslinked polyurethane network with branched flexible oligomers.
Mar and scratch resistance are a major concern for automotive and other industrial sectors from causing inconvenient aesthetic changes on clear coats. Then, a series of two-component solvent-borne polyurethane coatings were formulated with branched polycaprolactone (PCL) oligomers. The effect of the partial substitution of acrylic polyols by tri- and tetra-functional PCL polyols on adhesion, chemical resistance, thermo-mechanical properties and aesthetic response was analysed. The PCL polyols drove to plasticised networks with lower glass transition temperature (Tg) and promoted rubbery state at room temperature.
Remarkable improvement of wear resistance
The associated growth in chain mobility did not appreciably affect the key performance of the coatings, apart from the chemical resistance of formulations with PCL triols. Furthermore, remarkable improvement of wear resistance from promoted recovery response was demonstrated. The clear coats with moderated content of PCL polyols yielded a reduced loss of specular gloss with time after repeated scrubbing operations by an abrasive paper. The proposed approach, thus, is presented as a versatile strategy to tailor the mechanical surface properties of clear coats.
The study has been published in Progress in Organic Coatings, Volume 163, February 2022.
