Basf Coatings Gmbh

Bianca Goeb

Bernhard Steinmetz

Hardy Reuter

Matthias Blohm

Carsten Teichmann

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.

Method for producing a multicoat paint system

An aqueous dispersion containing at least one copolymer, the copolymer being preparable by initially charging an aqueous dispersion of at least one polyurethane, and then polymerizing a mixture of olefinically unsaturated monomers in the presence of the polyurethane, where a water-soluble initiator is used, the metered addition of the olefinically unsaturated monomers is effected in such a way that a concentration of 6.0% by weight, based on the total amount of olefinically unsaturated monomers, in the reaction solution is not exceeded over the entire duration of the reaction, and the mixture of the olefinically unsaturated monomers contains at least one polyolefinically unsaturated monomer.

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Werneck, Germany

Bianca Goeb