The influence of different components on interpenetrating polymer network's (IPN's) characteristics as automotive top coats

The aim of this study was to investigate the influence of different components of interpenetrating polymer networks (IPNs) on their behavior in dual curing automotive applications. Dual curing is one of possible ways to obtain fast curing, scratch resistant coatings for use in OEM and car refinish applications. Dual curing systems, upon hardening, represent interpenetrating networks (IPNs) [1]. IPN's were obtained using novel acrylate-terminated hyperbranched polyester with high functionality and compared to classical 2-pack polyurethane clear coat.In our previous manuscript [1] we investigated the influence of the acrylated hyperbranched polyester (HBP(A)) content in dual curing systems. In this article we studied the influence of the reactive diluent on dual curing compositions. To this end, we have chosen IPN with 50/50 weigth ratio of polyurethane (PU) and polyacrylic (PA) component. In order to determine more clearly the role of the HBP(A) in one IPN HBP(A) was changed with hexane diol diacrylate (HDDA), keeping the same ratio with EHA.The IPNs were characterized by dynamic-mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The mechanical properties of the IPNs were also investigated. The IPN with HDDA as reactive diluent, had the best performance. IPN with HBP(A) had the highest glass transition temperature Tg and the highest crosslink density, but it did not have the highest hardness.