Cationic, Thermally Cured Coatings Using Epoxidized Soybean Oil

By Ramya Raghavachar, Greg Sarnecki, Jamil Baghdachi, Massingill

Cycloaliphatic epoxy resins are used in coatings and inks because of their exceptionally low viscosity and reactivity with a variety of co-reactants, thus permitting high-solids and zero VOC coatings. The low viscosity of epoxidized soybean oil (ESBO), its reactivity, and relatively low cost make it an inexpensive candidate co-resin in cationic thermally cured coatings and inks using blocked acid catalysts.

Formulations with up to 40% ESBO in the epoxy resin blend were investigated. Blending of cycloaliphatic resin with 10% ESBO gave a bake coating with the same results as the standard formulation except pencil hardness was one unit lower when cured for 12 min at 120°C with a heat de-blocked catalyst. The hardness of coatings with ESBO is adjustable by chang-ing the epoxy/polyol ratio, using harder polyols and harder epoxy resins.