Method for passivating metallic surfaces by using itaconic acid homopolymers or copolymers

Abstract

A process for passivating a metallic surface by treating it with an acidic aqueous preparation comprising at least one itaconic acid homo- or copolymer. Passivating layers and metallic surfaces obtainable by means of the process.

1 - 20 . (canceled) 
   
   
       21 . A process for passivating a metallic surface by treating it with an acidic aqueous preparation comprising at least one water-soluble or water-dispersible itaconic acid copolymer, wherein the copolymer has been constructed from the following monomeric units:
 (A) 15% to 45% by weight of itaconic acid,   (B) 55% to 85% by weight of at least one monoethylenically unsaturated monocarboxylic acid,   (C) 5% to 40% by weight of vinylphosphonic acid, and   (D) optionally 0% to 30% by weight of at least one further ethylenically unsaturated monomer, other than (A), (B) and (C),   
     the amount being based in each case on the total amount of all of the monomers incorporated in the copolymer, and the copolymer being obtainable by means of free-radical polymerization in aqueous solution at a temperature of less than 120° C. 
   
   
       22 . The process according to  claim 21 , wherein the amount of vinylphosphonic acid is 10% to 30% by weight. 
   
   
       23 . The process according to  claim 21 , wherein the polymer is a terpolymer of 67% to 75% acrylic acid, 23% to 30% itaconic acid, and 0.1% to 10% vinylphosphonic acid, by weight. 
   
   
       24 . The process according to  claim 21 , wherein the polymer is a terpolymer of 55% to 65% acrylic acid, 15% to 25% itaconic acid, and 15% to 25% vinylphosphonic acid, by weight. 
   
   
       25 . The process according to  claim 21 , wherein the polymerization is performed at a temperature from 90 to 105° C. 
   
   
       26 . The process according to  claim 21 , wherein said metallic surface is of Zn, Al or alloys thereof. 
   
   
       27 . The process according to  claim 21 , being a substantially chromium-free process. 
   
   
       28 . The process according to  claim 21 , wherein the treating takes place by means of rolling, spraying or dipping methods. 
   
   
       29 . The process according to  claim 21 , wherein the metal surface is the surface of a strip metal. 
   
   
       30 . The process according to  claim 29 , wherein the strip metal is electrolytically galvanized or hot-dip-galvanized steel. 
   
   
       31 . The process according to  claim 29 , wherein the treating is performed by means of a continuous process. 
   
   
       32 . The process according to  claim 29 , wherein the surface is contacted with the preparation for a time of from 1 to 60 s. 
   
   
       33 . The process according to  claim 21 , wherein the formulation further comprises benzo- and/or tolyltriazole. 
   
   
       34 . A water-soluble or water-dispersible itaconic acid copolymer constructed from the following monomeric units:
 (A) 15% to 45% by weight of itaconic acid,   (B) 55% to 85% by weight of at least one monoethylenically unsaturated monocarboxylic acid,   (C) 5% to 40% by weight of vinylphosphonic acid, and   (D) optionally 0% to 30% by weight of at least one further ethylenically unsaturated monomer, other than (A), (B) and (C),   
     the amount being based in each case on the total amount of all of the monomers incorporated in the copolymer, and the copolymer being obtainable by means of free-radical polymerization in aqueous solution at a temperature of less than 120° C. 
   
   
       35 . The copolymer according to  claim 34 , wherein the amount of vinylphosphonic acid is 10% to 30% by weight. 
   
   
       36 . The copolymer according to  claim 34 , wherein the polymer is a terpolymer of 67% to 75% acrylic acid, 23% to 30% itaconic acid, and 0.1% to 10% vinylphosphonic acid, by weight. 
   
   
       37 . The copolymer according to  claim 34 , wherein the polymer is a terpolymer of 55% to 65% acrylic acid, 15% to 25% itaconic acid, and 15% to 25% vinylphosphonic acid, by weight. 
   
   
       38 . The copolymer according to  claim 34 , wherein the polymerization is performed at a temperature from 90 to 105° C.