Patent ID: 7198824

Claim:
A process for producing multicoat color and/or effect paint systems on primed or unprimed substrates, comprising: (I) preparing a basecoat film by applying an aqueous basecoat material to (I.1) an uncoated substrate, (I.2) a thermally cured surfacer coated substrate, or (I.3) a dry surfacer film coated substrate, (II) drying the basecoat film, (III) preparing a clearcoat film by applying a powder slurry clearcoat material to the basecoat film, and (IV) jointly curing at least the basecoat film (II) and the clearcoat film (III), to give the basecoat and the clearcoat and; characterized in that the aqueous basecoat material comprises at least one graft copolymer that is the reaction product of a free radical polymerization of a mixture of at least one (meth)acrylic monomer (a1) containing at least one isocyanate-reactive functional group and at least one (meth)acrylic monomer (a2) copolymerizable therewith in the presence of a self-crosslinking polyurethane (B) in an aqueous medium, said self-crosslinking polyurethane (B) containing on average per molecule at least one pendant and/or at least one terminal olefinically unsaturated group and at least one isocyanate group blocked with a monofunctional blocking agent selected from the group consisting of phenols, lactams, active methylenic compounds, alcohols, mercaptans, acid amines, imides, imines, oximes and ketoximes, salts of sulphurous acid, hydroxamine esters, substituted pyrazoles, and mixtures thereof; said at least one graft copolymer comprising repeating units resulting from the free radical polymerization of (meth)acrylic monomer (a1), (meth)acrylic monomer (a2), and self-crosslinking polyurethane (B).