A complete new design for waterborne 2-pack PUR coatings with robust application properties

In this paper, a new approach to the paint composition design of WB 2-pack PUR coatings for car refinish application is presented. New hydroxy-functional binder emulsions are described that offer a better basis for the mixing process and the pot-life/reactivity balance with polyisocyanate hardeners. In addition, it will be shown that with these binder systems the overall balance of appearance, pot-life and curing speed can be enhanced to a very attractive level by the use of a well tuned catalyst package, allowing sufficient time for application, flow and de-aeration while offering the required fast curing characteristics as well. Thirdly, it will be shown how the aspects relating to undesired foam formation can be managed. Finally, the performance of low VOC paint compositions for car refinish application based on this new generation of WB 2-pack PUR system will be discussed.