Preparation and Physical Properties of Two-Packaged Polyurethane Coatings for Silver Mirror Layer Protection

The gel fraction and the curing rate of the silver mirror protective film according to the curing condition were investigated. Two-packaged polyurethane dry film made from acryl polyol and three different isocyanate curing agents (HDI-biuret, HDI-trimer and IPDI trimer) were built on the silver mirror layer in order to protect the layer. FTIR/ATR spectra showed the isocyanate content was clearly decreased and the gel fraction was increased as curing temperature and time were increased. The optimum curing condition of the silver mirror protective film was 80□ and 30 minutes. The dry film prepared with the optimum condition satisfied all tests in our materials specification for automotive interior parts. Moreover, the pencil hardness of the film containing dibutyltin dilaurate was stronger than the film without catalyst.