Synthesis of new acrylic polyols and study of the film properties of NBDI isocyanurate on the two-package polyurethane coating system

Abstract

A variety of acrylic polyols were synthesized in order to study the effects of three variables, hydroxyl value (OHV), molecular weight (MW) and acid value (AV), The influence of hardeners, NBDI and IPDI isocyanate were also analyzed. As a result, the polyurethane films prepared from acrylic polyols with hardeners were analyzed the physical properties of the film as follows, pencil hardness, bending, dupont impact, chemical resistance, drying time, gel time, weathering and tensile strength. These results were discussed in relation to dynamic mechanical analysis (DMA). The most significant factor that influence on film properties is OHV. The films that posses high dupont impact has low chemical resistance. The NBDI's films give higher dupont impact but lower chemical resistance than IPDI's. The reactivity of NBD is higher than that of IPDI as seen evidently in drying time and gel time results. The gloss retention and yellowness test of film in the exposure and QUV test between two hardenes was not so different. The tensile strength of NBDI's film was less than that of IPDI's whereas the elongation of NBDI's film was much higher than that of IPDI's (about 8 times). In DMA results, the NBDI's films give the lower glass transition temperature and the lower crosslinking density which result in the higher toughness and the lower chemical reisistance of the films, respectively.