Patent ID: 8734949

Claim:
A method for passivating a metallic surface, which comprises treating the surface in alternating layers with a) then with b), a) always being the first and last layer, such that a multicoat passivating layer is provided on said metallic surface, said multicoat passivating layer comprising 3n+2 alternating layers where n is an integer and the layer sequence is a), b), n times {a), b)} and lastly a), where a) and b) are: a) an acidic, aqueous preparation comprising at least one water-soluble copolymer (A) synthesized from (a1) 15% to 99.9% by weight of (meth)acrylic acid or a salt thereof and (a2) 0.1% to 85% by weight of at least one further monoethylenically unsaturated monomer, which is different from (a1) and which comprises acidic groups, and also, optionally, (a3) 0% to 55% by weight of at least one further ethylenically unsaturated monomer, which is different from (a1) and (a2); b) an aqueous preparation comprising at least one water-soluble and/or water-dispersible species (B) which comprises cationic and/or procationic groups.