Improvements to the processes for the production of coatings by electrophoretic deposition from polymers miscible with water

摘要

An electrolyte for electrodeposition of stovable coatings consists of a water-diluted ammonium or amine salt of a formaldehyde reaction product of a copolymer obtained from acrylamide and/or methacrylamide and at least two other ethylenically-unsaturated monomers, one of which is a carboxylic acid, the copolymer having a molecular weight of from 5000 to 15,000. The copolymer may be obtained by polymerization in a solvent, which is preferably water-miscible, using a mercaptan regulator, e.g. tert.-dodecylmercaptan, and a peroxide or azo-compound as accelerator. Suitable comonomers include acrylic and methacrylic acids and their esters; maleic and fumaric acids and their half-esters and diesters; and styrene and its derivatives, e.g. methyl-styrene and vinyl toluene. The copolymer is then reacted with formaldehyde, which may be used in alcoholic or aqueous solution, and neutralized with ammonia or an amine, e.g. triethylamine or dimethylethanol-amine. In the example given the copolymer is produced using by weight: 70 parts butanol, 8 parts acrylic acid, 15 parts acrylamide, 25 parts styrene, 25 parts acrylic acid butyl ester, 27 parts acrylic acid ethyl ester, 1 part di-tert. butyl peroxide, 5 parts tert. dodecylmercaptan. After methylolation and neutralization, the product is diluted with water and pigmented with TiO2.ALSO:Electro-phororetically produced coatings are produced using as electrolyte a water-diluted ammonium or amine salt of a formaldehyde reaction product of a copolymer obtained from acrylamide and/or methacrylamide and at least two other ethylenically - unsaturated monomers one of which is a carboxylic acid, in which the polymer used has molecular weight of from 5,000 to 15,000. The copolymer may be formed using as the carboxylic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid or the half-ester of maleic or fumaric acid; and as the other comonomer acrylic and/or methacrylic acid esters, maleic or fumaric acid di-esters or styrene may be used. The resulting polymer may be reacted with formaldehyde prior to or after neutralization thereof using ammonia; primary, secondary or testiary amines, or alkano-amines, e.g. triethyamine or demethyethanolamine. After deposition the deposited film is preferably stoved at 120-200 DEG C. The electrolyte may be pigmented with Ti O2.