Research Of Graft Modified Epoxy-acrylic Resins Used In Anticorrosive Emulsion

Aqueous coatings have lots of advantages, such as no poison, no smell, little pollution. It coincides with the developing trend of the coating at present. Epoxy resin is widely used in the field of anticorrosive coating industry because of its high adhesive and good chemical resistant. But epoxy resin is indissolvable in water, only dissolvable in organic solvent. Acrylic resin is usually used as base material of coatings because of its excellent gloss and weather resisting property. Epoxy resin can be modified by acrylic acid, then be neutralized to water dispersion. It accommodates coating industry's requirement of saving resources and protecting environment.This paper deals with the polymerizing conditions of epoxy-acrylic composition, which is reacted in the presence of benzoyl peroxide at about 120.degree.C. The reaction mixture obtained contains: (a) unreacted epoxy resin; (b) graft polymer; and (c) associatively formed but ungrafted addition polymer. The graft polymer is formed from the epoxy resin by the grafting of addition polymer onto aliphatic backbone carbons of the epoxy resin, such grafting being at carbons that have either one or two hydrogens bonded thereto in the ungrafted state. The carboxyl-containing epoxy-acrylic resins was neutralized and dispersed in an aqueous medium. The waterborne epoxy-acrylate emulsion was synthesized. The factors affecting the water dispersion stability of copolymer resins, such as grafting reaction temperature and time, molecular weight of epoxy resin, acid number, initiator, solvents and neutralizer, were studied. Finally, the reaction principle of epoxy-acrylate grafting copolymer is proved by testing acid number and analyzing infra-red spectrum (IR).The curing regularity of film coating is investigated too. A series of coating films of different curing temperature and curing time were prepared. The curing regularity was determined by testing resistance to water and degree of cross linking of the coating film. Epoxy-acrylic resins are suitable for an aqueous coating composition, which is capable of forming a coating film excellent in adhesive power, corrosionresistance, water resistance, flexibility, among others. And it meets the necessity of environmental protection.