| 摘要 |
1,184,549. Electro-deposition of paints. COURTAULDS Ltd. July 19, 1967 [July 20, 1966], No. 32578/66. Heading C7B. In a method of electro-painting an anode with an aqueous paint embodying a polyanionic binder which is solid at room temperature, the aqueous paint electrolyte is maintained below the coalescence temperature of the binder and allowing the paint film coating the anode to attain said coalescence temperature whilst deposition is taking place, whereupon further electro-deposition of the coated anode is inhibited. The polyionic binder used may be a copolymer containing: (a) 5-55 wt % of one or more of styrene, vinyl acetate, methyl and ethyl acrylates and methacrylates; (b) 10-60 wt % of alkyl acrylates and methacrylates in which the alkyl group contains 3-12 carbon atoms, e.g. the 2-ethylhexyl esters, the n-octyl esters, the butyl esters and the n-hexyl esters thereof; (c) 7.5-15 wt % of N-alkoxy methyl derivative of acrylamide or methacrylamide, the alkoxy group having 1-3 carbon atoms; and (d) 1-20 wt % of alkali metal, ammonium or amine salts of acrylic, methacrylic or itaconic acids. The copolymer is preferably such that a 40% aqueous solution thereof has a viscosity #10 poises at 25‹ C. The electrolyte used may contain 10% solids. The film may be heated from an auxiliary source. The molecular weight of the binder may be limited by use of a mercaptan, e. g. 2-mercaptoethanol, and the paint may contain other water-miscible solvents e. g. alcohols. Alternatively the binder may be a partial phosphate ester made by reacting (a) one or more polymers having at least one epoxy group, e. g. dihydric phenol/epichlorhydrin condensates, with (b) excess orthophosphoric acid, alone or with one or more organic acids or anhydrides, e. g. the fatty acids of drying oils, e.g. linoleic or oleic acids, the binder being rendered soluble in water by neutralizing the residual acidity of the phospate ester with an alkali, ammonia or an amine. |
