This study demonstrates that 2K waterborne polyurethane clearcoats can be a technology of choice in automotive clearcoat applications in order to combine high-demanding requirements and sustainability development concerns.
Polyurethane chemistry is well established for high-performance coatings. This success over the years comes from the outstanding properties brought by polyurethane backbones such as high solvent and mechanical resistance (hardness/flexibility compromise), very good adhesion on various substrates, fast film forming and drying at room temperature, and excellent weathering resistance, provided that aromatic structures are absent from the polymer composition. These characteristics have made polyurethane-based coatings ideal candidates in application fields requiring high film appearance and resistance as in automotive car refinishing and OEM.
Over the last decades, solvent-based systems have dominated the market. However, more stringent regulations concerning VOC emissions in most countries have led paint manufacturers and raw material suppliers to develop alternative technologies to conventional solvent-based PUs, more respectful to the environment but offering the same level of performance. Thus, waterborne polyurethane coatings (1K and 2K systems) emerged at the end of the 1980s and are now being used in numerous applications.