Evaluation of bisacrylate terminated epoxy resins as coatings

The paper describes the effect of backbone flexibility on the coating performance of vinyl ester resin. For this purpose four resins of varying flexibility were prepared. Bisacrylate terminated epoxy resin (D) was prepared by reacting 2 mol of acrylic acid with 1 mol of diglycidyl ester of hexahydrophthalic anhydride. The flexibility of the backbone was increased by chain extension of mono acryloxy derivative of diglycidyl ester of hexahydrophthalic anhydride with sebacic acid (resin G′). Partial cross-linking of resin D containing pendant hydroxyl group was also done by reacting with small amounts of isophorone diisocyanate (D2I10, D2I4).Fifteen resin formulations were used to evaluate the coating performance in terms of hardness, scratch, adhesion, abrasion resistance and weatherability. Nanosilica and nano-ZnO were used as additives in few formulations for stabilizing transparent coated metallic substrates. The flexibility of the resin backbone (G′) improved adhesion performance of coatings. The increase in the cross-linking improved thermal stability (D2I10 and D2I4) of the resin. Weatherability was only marginally affected by the backbone structure.