METHOD FOR PRODUCING A MULTICOAT PAINT SYSTEM

摘要

The present invention relates to a method for producing a multicoat paint system on a metallic substrate, in which a basecoat or a plurality of directly successive basecoats are produced directly on a metallic substrate coated with a cured electrocoat, a clearcoat is produced directly on the one basecoat or the uppermost of the plurality of basecoats, and then the one or more basecoats and the clearcoat are jointly cured, and wherein at least one basecoat material used for production of the basecoats comprises at least one aqueous dispersion comprising at least one copolymer, said copolymer being preparable by (i) initially charging an aqueous dispersion of at least one polyurethane, and then (ii) polymerizing a mixture of olefinically unsaturated monomers in the presence of the polyurethane from (i), in which (a) a water-soluble initiator is used, (b) the olefinically unsaturated monomers are metered in such that a concentration of 6.0% by weight, based on the total amount of olefinically unsaturated monomers used for polymerization, in the reaction solution is not exceeded over the entire reaction time, and (c) the mixture of the olefinically unsaturated monomers comprises at least one polyolefinically unsaturated monomer.

主权项

1. A method for producing a multicoat paint system on a metallic substrate, comprising
(1) producing a cured electrocoat on the metallic substrate by electrophoretic application of an electrocoat to the substrate and subsequent curing of the electrocoat, (2) producing a basecoat or a plurality of directly successive basecoats directly on the cured electrocoat by applying an aqueous basecoat material directly to the electrocoat or applying a plurality of basecoat materials in direct succession to the electrocoat, (3) producing a clearcoat directly on the basecoat or an uppermost basecoat by applying a clearcoat material directly to the basecoat or the uppermost basecoat, (4) jointly curing the basecoat and the clearcoat or the basecoats and the clearcoat, wherein the basecoat material or at least one of the basecoat materials comprises at least one aqueous dispersion comprising at least one copolymer, said copolymer being preparable by
(i) initially charging an aqueous dispersion of at least one polyurethane, and then(ii) polymerizing a mixture of olefinically unsaturated monomers in the presence of the polyurethane from (i),
in which(a) a water-soluble initiator is used,(b) the olefinically unsaturated monomers are metered in such that a concentration of 6.0% by weight, based on the total amount of olefinically unsaturated monomers used for polymerization, in the reaction solution is not exceeded over the entire reaction time, and(c) the mixture of the olefinically unsaturated monomers comprises at least one polyolefinically unsaturated monomer.