| 摘要 |
A water-dispersed coating composition for metals has a pH value within the alkaline range and comprises a copolymer dispersion containing as constituent monomers, a monovinyl aromatic hydrocarbon, an a , b -olefinic unsaturated carboxylic ester and 6-20 parts by wt./100 parts of copolymer of an a , b -olefinic unsaturated carboxylic acid, and sufficient chromium trioxide, water soluble (e.g. ammonium) chromate and/or water soluble (e.g. zinc or ammonium)bichromate to provide 0.05-0.5 chromium atoms/carboxyl group of the a ,b -olefinic unsaturated acid. The pH of the dispersion may be made 9-12 by addition of ammonia. The copolymer may be derived from styrene or vinyl toluene, a C4- 12 alkyl (e.g. butyl or 2-ethylhexyl) acrylate or methyl or glycidyl methacrylate, acrylic, methacrylic or itaconic acid and acrylonitrile or acrylamide. The dispersion may be coated on a metal and cured by heating. The dispersion may be made by polymerizing an aq. mixture of the monomers containing sodium di-n-octyl sulphosuccinate, sodium n-butyl naphthalene sulphonate, polyoxyethylene nonylphenyl ether and potassium persulphate. The dispersion may also contain di-n-butyl phthalate and titanium dioxide.ALSO:A water-dispersed coating composition for metals has a pH value within the alkaline range and comprises a copolymer dispersion containing as constituent monomers, a monovinyl aromatic hydrocarbon, an a , b -olefinic unsaturated carboxylic ester and 6-20 parts by wt./100 parts of copolymer of an a , b -olefinic unsaturated carboxylic acid, and sufficient chromium trioxide, water soluble chromate and/or water soluble bichromate to provide 0.05-0.5 chromium atoms/carboxyl groups of the a , b -olefinic unsaturated acid. The pH of the dispersion may be made 9-12 by addition of ammonia. The coating composition may be applied to the surface of aluminium, zinc, tin, copper, iron or stainless steel, and the coating may be cured by heating for 1/2 -15 min. at 150-280 DEG C. so that the chromium compound diffuses into the copolymer particles of the dispersion and forms a corrosion resisting coating. |
