GRAFT POLYMER COMPOSITIONS OF TERMINATED EPOXY RESIN, PROCESSES FOR MAKING AND USING SAME, AND SUBSTRATES COATED THEREWITH

摘要

GRAFT POLYMER COMPOSITIONS OF TERMINATED EPOXY RESIN, PROCESSES FOR MAKING AND USING SAME. AND SUBSTRATES COATED THEREWITH Epoxy resin is reacted with a terminating agent to eliminate at least part of the epoxide groups of the resin and form modified resin. The epoxy resin or such modified resin is also reacted with addition polymerizable monomer at elevated temperature in the presence of at least 3% of benzoyl peroxide based on the weight of such monomer. Generally the latter reaction is done at about 110.degree.C to about 120.degree.C. These two reactions can be performed in any desired sequence, or simultaneously. The final reaction mixture produced contains: (a) graft polymer; (b) ungrafted, modified resin; and (c) ungrafted addition polymer, formed associatively with the graft polymer. While other kinds of grafting can and often do occur between addition polymer and the epoxy resin or modified resin, the term "graft polymer" herein connotes specifically carbon-to-carbon grafting of addition polymer onto the modified resin. The proportion of the graft copolymer in the final reaction mixture is effective for imparting outstanding dispersion stability to aqueous dispersions of the reaction mixture. The modification eliminates vagaries of epoxy reactions. Accordingly, the invention is useful for making coating compositions. The compositions thus can have good weather resistance and are particularly useful for making sanitary coatings for cans for foods and beverages, especially for beer. The coatings compositions can be aqueous dispersions for spray application or concentrates or powders that can be made up readily into aqueous sprayable coating compositions. Organic solvent vehicles also can be used.