A new curing system for automotive topcoat

In response to the need for an acid rain resistant topcoat, a curing system was prepared using two kinds of acrylic polymers; one contains a half-ester of acid anhydride and the other both a hydroxyl and glycidyl group as the functional groups. The half-ester group polymer does not react with a hydroxyl group at room temperature, but releases alcohol and reproduces an acid anhydride at elevated temperatures, and subsequently rapid polymer-polymer reaction through acid anhydride and hydroxyl group occurs. Carboxyl group produced during this crosslinking reaction reacts with glycidyl group. This reaction made it possible to design a one component curing system with a higher crosslink density. Upon adapting the curing system for automotive clearcoat, a function of mar resistance was also necessary, which was achieved by using hydroxyl monomer containing longer alkylene group. (C) 2001 Published by Elsevier Science B.V.