NOVEL CROSS-LINKING SYSTEM WITH HYDROXYL-CONTAINING POLYMER, ALICYCLIC POLYEPOXIDE AND POLYALKOXYSILANE

The crosslinking system based on the reaction among alicyclic epoxide group, hydroxyl group and alkoxysilyl group in the presence of aluminu m beta-diketone chelate have been developed. Five kinds of reaction ar e possible, and the result of gas chromatography and infrared analyses indicated that the main reaction is the ring-opening reaction of alic yclic epoxide group with hydroxyl group and/or hydroxysilyl group. The acrylic resin obtained by free radical polymerization of these three kinds of functional monomers and non-functional monomers showed good c uring property, and the film was superior in acid rain resistance and outdoor durability. The resin is suitable to use in automotive 2coat-1 bake clear coat. The viscosity of this binder system was remarkably re duced by addition of a low molecular weight alicyclic polyepoxide comp ound and an alkoxysilane oligomer without affecting to its good curing property. Such a system made it possible to design novel high solid c oatings. It was found that the crosslinking could be extended to the c ombination of a polyester polyol, an alicyclic epoxide compound and an alkoxysilane oligomer. Ln this case, it was necessary that the polyes ter polyol contained highly reactive terminal hydroxyl group in the br anch chains. (C) 1997 Elsevier Science S.A.