Abstract: A coating composition substantially free of volatile organic compounds and containing a film-forming polymeric binder comprising epoxy crosslinked microgel particles having a particle size less than about 0.15 microns. The microgel particles are produced by first dispersing carboxyl functional addition copolymer dispersant into water followed by dispersing carboxyl functional polyester oligomer and diepoxide resin into the aqueous dispersant, and then esterifying the epoxy resin with the carboxyl functionality on the copolymer and oligomer. In a further variation, the polyester oligomer can contain maleic or fumaric unsaturation and subsequently grafted with in-situ copolymerized ethylenic monomers.

Abstract: An aqueous dispersed, very low VOC (less than about 0.4 pounds per gallon), protective surface coating composition comprises crosslinked microgel particles of less than 1 micron and produced by dispersing low molecular weight carboxyl functional addition copolymer into water, stably dispersing diepoxide epoxy resin in the aqueous dispersion, and coreacting the diepoxide resin with the carboxyl functional copolymer to provide epoxy-ester crosslinked microgel polymer particles stably dispersed into water. The microgel particles are useful as a polymeric binder for aqueous dispersed coatings particularly useful for coating interior surfaces of beer and beverage cans.