| 摘要 |
The present invention relates to a method for producing a multi-layer finish on a metal substrate, wherein a base lacquer layer or a plurality of directly consecutive base lacquer layers are produced directly on a metallic substrate coated with a hardened electrophoretic dip painting, a clear lacquer coat is produced directly on the one or the upper of the plurality of said base lacquer layers, and the one or the plurality of base lacquer coatings and the clear lacquer coat are subsequently hardened together. The method is characterized in that at least one base lacquer employed for producing the base lacquer layers comprises at least one aqueous dispersion containing at least one copolymer. The copolymer can be produced by (i) providing an aqueous dispersion of at least one polyurethane followed by (ii) polymerization of a mixture of olefinically unsaturated monomers in the presence of the polymer produced in (i), wherein (a) a water-soluble initiator is employed, and wherein (b) the dosing of the olefinically unsaturated monomer is performed such that in the reaction solution a concentration of 6.0 wt.% relative to the total amount of the olefinically unsaturated monomers employed for polymerization is not exceeded during the entire reaction time, and wherein (c) the mixture of olefinically unsaturated monomers contains at least one olefinically polyunsaturated monomer. |
