Patent ID: 8568522

Claim:
An acidic preparation for passivating metallic surfaces with a pH of less than or equal to 5, comprising water and 0.1 to 50% by weight, based on the amount of all components of said acidic preparation, of at least one water-soluble or water-dispersible copolymer comprising phosphoric and/or phosphonic acid groups, wherein aqueous dispersions of crosslinking polymer particles of water-insoluble polymers are excluded, and wherein said at least one water-soluble or water-dispersible copolymer consists of the following monomeric units: (A) 5 to 80% by weight of at least one mono(meth)acrylic ester of formula H 2 C═CHR 1 —COOR 2 , wherein R 1 is H or methyl and R 2 is a radical selected from the group consisting of: (R 2a ) radicals of formula —(R 3 —O—) n —R 4 , wherein n is an integer from 2 to 40, R 3 is, independently on each occurrence, a divalent, linear, or branched alkyl radical having from 2 to 4 C atoms, and R 4 is H or a linear or branched alkyl radical having from 1 to 6 C atoms; (R 2b ) radicals of formula —R 5 —X m , wherein R 5 is an (m+1)-valent, linear or branched alkyl radical having from 1 to 10 C atoms, X is a functional group selected from the group consisting of —OH, —OR 6 , —NH 2 , —NHR 6 , —NR 2 6 , —N + HR 2 Y − , and —N + R 3 Y − , wherein R 6 is methyl or ethyl and Y is a monovalent anion, and m is an integer from 1 to 6, with the proviso that there is not more than one functional group X per C atom in R 5 ; and (R 2c ) a mono- or oligosaccharide radical; (B) 10 to 75% by weight of at least one monoethylenically unsaturated monomer which comprises phosphoric and/or phosphonic acid groups and/or salts and/or esters thereof; (C) 5 to 70% by weight of at least one monoethylenically unsaturated monomer which comprises at least one COOH group and/or salts thereof; and (D) 0 to 30% by weight of further ethylenically unsaturated monomers differing from (A), (B), and (C).