STUDIES ON CURING BEHAVIOR OF POLYACRYLATE-EPOXY COMPLEX COATING

The curing behavior of a polyacrylate-epoxy complex coating system was studied by torsion braid analysis (TBA) and in situ Fourier transform -infrared (FTIR). The results of TBA with heating show that the curing process consists of two steps. The first step is a deblocking and cro sslinking period, and is the main period of the curing process. The se cond step is a deep-curing period. At the end of this step, a greater extent of crosslinking was obtained. Furthermore, the results of in si tu FTIR prove that the changes occurring in the second step concern th e reaction of the deblocked isocyanate group and an NH group which com es from urethane. Through isothermal TBA testing the Arrhenius apparen t activation energies of the curing system with and without a dibutylt in dilaurate catalyst were calculated, and the results show that the d ibutyltin dilaurate catalyst could shorten the curing time, while lowe ring the curing temperature and apparent activation energy efficiently . (C) 1998 Elsevier Science Ltd. All rights reserved.