Method for providing metal surfaces with protection against corrosion

Abstract

A process for the anti-corrosive treatment of vehicle bodies or domestic appliances which have, at least in part, a metal surface and wherein this metal surface consists of at least 90%, based on the metal surface, zinc, aluminum and/or magnesium and/or alloys of these metals with one another or with other alloying elements, wherein the vehicle bodies or domestic appliances are cleaned, passivated and painted, characterised in that, for the purpose of passivation, the vehicle bodies or domestic appliances are contacted with an aqueous solution having a pH of 1 to 12 and containing complex fluorides of Ti, Zr, Hf, Si and/or B in a quantity such that the content of Ti, Zr, Hf, Si and/or B is 20 to 500 mg/l, and 50 to 2000 mg/l organic polymers, the composition of the aqueous solution being selected such that no crystalline zinc-containing phosphate layer is formed on the metal surface.

1 . A process for the anti-corrosive treatment of vehicle bodies or domestic appliances which have, at least in part, a metal surface and wherein this metal surface consists of at least 90%, based on the metal surface, zinc, aluminum and/or magnesium and/or alloys of these metals with one another or with other alloying elements, wherein the vehicle bodies or domestic appliances are cleaned, passivated and painted, 
 characterised in that, for the purpose of passivation, the vehicle bodies or domestic appliances are contacted with an aqueous solution having a pH of 1 to 12 and containing complex fluorides of Ti, Zr, Hf, Si and/or B in a quantity such that the content of Ti, Zr, Hf, Si and/or B is 20 to 500 mg/l, and 50 to 2000 mg/l organic polymers, the composition of the aqueous solution being selected such that no crystalline zinc-containing phosphate layer is formed on the metal surface.    
     
     
         2 . A process as claimed in  claim 1  wherein the aqueous solution contains complex fluorides of Ti, Zr, Hf, Si and/or B in a quantity such that the content of Ti, Zr, Hf, Si and/or B is 50 to 400 mg/l.  
     
     
         3 . A process as claimed in one of claims  1  or  2  wherein the aqueous solution contains 100 to 1000 mg/l organic polymers.  
     
     
         4 . A process as claimed in one or more of  claims 1  to  3  wherein the organic polymers are selected from epoxy resins, amino resins, tannins, phenol-formaldehyde resins, polycarboxylic acids, polymeric alcohols and/or the esterification products thereof with polycarboxylic acids, poly-4-vinylphenol compounds, amino group-containing homo- or co-polymer compounds and polymers or copolymers of vinyl pyrrolidone.  
     
     
         5 . A process as claimed in  claim 4  wherein the organic polymers are selected from poly-4-vinylphenol compounds corresponding to general formula (I):  
       
         
           
           
               
               
           
         
       
       wherein 
 n represents a number between 5 and 100,  
 x independently represents hydrogen and/or CRR 1 OH groups wherein R and R 1  represent hydrogen, aliphatic and/or aromatic radicals having 1 to 12 carbon atoms.  
 
     
     
         6 . A process as claimed in  claim 4  wherein the organic polymers are selected from amino group-containing homo- or co-polymer compounds, comprising at least one polymer selected from the group consisting of (a), (b), (c) or (d), wherein: 
 (a) comprises a polymer material having at least one unit of the formula:  
                     
 wherein: 
 R 1  to R 3 , independently for each of the units, are selected from the group consisting of hydrogen, an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 18 carbon atoms;  
 Y 1  to Y 4 , independently for each of the units, are selected from the group consisting of hydrogen, —CR 11 R 5 OR 6 , —CH 2 Cl or an alkyl or aryl group having 1 to 18 carbon atoms or Z:  
                     
  but at least a fraction of the Y 1 , Y 2 , Y 3  or Y 4  of the homo- or co-polymer compound or material must be Z; R 5  to R 12 , independently for each of the units, are selected from the group consisting of hydrogen, an alkyl, aryl, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group;  
 R 12  may also be —O (−1)  or —OH;  
 W 1 , independently for each of the units, is selected from the group consisting of hydrogen, an acyl, an acetyl, a benzoyl group; 3-allyloxy-2-hydroxypropyl; 3-benzyloxy-2-hydroxypropyl; 3-butoxy-2-hydroxypropyl; 3-alkyloxy-2-hydroxypropyl; 2-hydroxyoctyl; 2-hydroxyalkyl; 2-hydroxy-2-phenylethyl; 2-hydroxy-2-alkylphenylethyl; benzyl; methyl; ethyl; propyl; alkyl; allyl; alkylbenzyl; haloalkyl; haloalkenyl; 2-chloropropenyl; sodium; potassium; tetraarylammonium; tetraalkylammonium; tetraalkylphosphonium; tetraarylphosphonium or a condensation product of ethylene oxide, propylene oxide or a mixture or a copolymer thereof;  
 
 (b) comprises: 
 a polymer material with at least one unit of the formula:  
                     
 
 wherein: 
 R 1  to R 2 , independently for each of the units, are selected from the group consisting of hydrogen, an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 18 carbon atoms;  
 Y 1  to Y 3 , independently for each of the units, are selected from the group consisting of hydrogen, —CR 4 R 5 OR 6 , —CH 2 Cl or an alkyl or aryl group having 1 to 18 carbon atoms or Z:  
                     
  but at least a fraction of the Y 1 , Y 2 , or Y 3  of the end compound must be Z; R 4  to R 12 , independently for each of the units, are selected from the group consisting of hydrogen, an alkyl, aryl, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group; R 12  may also be —O (−1)  or —OH;  
 W 2 , independently for each of the units, is selected from the group consisting of hydrogen, an acyl, an acetyl, a benzoyl group; 3-allyloxy-2-hydroxypropyl; 3-benzyloxy-2-hydroxypropyl; 3-alkylbenzyloxy-2-hydroxypropyl; 3-phenoxy-2-hydroxypropyl; 3-alkylphenoxy-2-hydroxypropyl; 3-butoxy-2-hydroxypropyl; 3-alkyloxy-2-hydroxypropyl; 2-hydroxyoctyl; 2-hydroxyalkyl; 2-hydroxy-2-phenylethyl; 2-hydroxy-2-alkylphenylethyl; benzyl; methyl; ethyl; propyl; alkyl; allyl; alkylbenzyl; haloalkyl; haloalkenyl; 2-chloropropenyl or a condensation product of ethylene oxide, propylene oxide or a mixture thereof;  
 
 (c) comprises: 
 a copolymer material, wherein at least part of the copolymer has the structure  
                     
  and at least a fraction of the above part is polymerised with one or more monomers, which are selected, independently for each unit, from the group consisting of acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, vinyl acetate, vinyl methyl ketone, isopropenyl methyl ketone, acrylic acid, methacrylic acid, acrylamide, methacrylamide, n-amyl methacrylate, styrene, m-bromostyrene, p-bromostyrene, pyridine, diallyldimethylammonium salts, 1,3-butadiene, n-butyl acrylate, t-butylaminoethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, n-butyl vinyl ether, t-butyl vinyl ether, m-chlorostyrene, o-chlorostyrene, p-chlorostyrene, n-decyl methacrylate, N,N-diallyl melamine, N,N-di-n-butylacrylamide, di-n-butyl itaconate, di-n-butyl maleate, diethylaminoethyl methacrylate, diethylene glycol monovinyl ether, diethyl fumarate, diethyl itaconate, diethyl vinyl phosphate, vinylphosphonic acid, diisobutyl maleate, diisopropyl itaconate, diisopropyl maleate, dimethyl fumarate, dimethyl itaconate, dimethyl maleate, di-n-nonyl fumarate, di-n-nonyl maleate, dioctyl fumarate, di-n-octyl itaconate, di-n-propyl itaconate, N-dodecyl vinyl ether, acidic ethyl fumarate, acidic ethyl maleate, ethyl acrylate, ethyl cinnamate, N-ethyl methacrylamide, ethyl methacrylate, ethyl vinyl ether, 5-ethyl-2-vinylpyridine, 5-ethyl-2-vinylpyridine-1-oxide, glycidyl acrylate, glycidyl methacrylate, n-hexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, isobutyl methacrylate, isobutyl vinyl ether, isoprene, isopropyl methacrylate, isopropyl vinyl ether, itaconic acid, lauryl methacrylate, methacrylamide, methacrylic acid, methacrylonitrile, N-methylolacrylamide, N-methylolmethacrylamide, N-isobutoxymethylacrylamide, N-isobutoxymethylmethacrylamide, N-alkyloxymethyl acrylamide, N-alkyloxymethylmethacrylamide, N-vinyl caprolactam, methyl acrylate, N-methylmethacrylamide, α-methyl styrene, m-methyl styrene, o-methyl styrene, p-methyl styrene, 2-methyl-5-vinylpyridine, n-propyl methacrylate, sodium-p-styrene sulfonate, stearyl methacrylate, styrene, p-styrenesulfonic acid, p-styrenesulfonamide, vinyl bromide, 9-vinylcarbazole, vinyl chloride, vinylidene chloride, 1-vinylnaphthalene, 2-vinylnaphthalene, 2-vinylpyridine, 4-vinylpyridene, 2-vinylpyridine-N-oxide, 4-vinylpyrimidine, N-vinyl pyrrolidone; and W 1 , Y 1 -Y 4  and R 1 -R 3  are as defined under (a);  
 
 (d) comprises a condensation polymer of the polymeric materials (a), (b) or (c), wherein a condensable form of (a), (b), (c) or a mixture thereof is condensed with a second compound which is selected from the group consisting of phenols, tannins, novolak resins, lignin compounds, together with aldehydes, ketones or mixtures thereof, to produce a condensation resin product wherein the condensation resin product, by adding “Z” to at least a part thereof, then reacts further by reaction of the resin product with (1) an aldehyde or ketone (2) a secondary amine to form a final adduct which may react with an acid.  
 
     
     
         7 . A process as claimed in  claim 6  wherein at least a fraction of the groups Z of the organic polymer has a polyhydroxyalkylamine functionality, which results from the condensation of an amine or ammonia with a ketose or aldose having 3 to 8 carbon atoms.  
     
     
         8 . A process as claimed in  claim 6  wherein the organic polymer represents a condensation product of a polyvinylphenol having a molecular weight in the range of 1000 to 10,000 with formaldehyde or paraformaldehyde and with a secondary organic amine.  
     
     
         9 . A process as claimed in one or more of  claims 1  to  8  wherein the aqueous solution additionally contains 0.001 to 2 g/l in each case of one or more of the metals Mn, Ce, Li, V, W, Mo, Mg, Zn, Co and Ni.  
     
     
         10 . A process as claimed in one or more of  claims 1  to  9  wherein the aqueous solution additionally contains 0.001 to 1.5 g/l each of phosphoric acid, phosphorous acid, phosphonic acid and/or the respective anions and/or the respective esters thereof.  
     
     
         11 . A process as claimed in one or more of  claims 1  to  10  wherein the aqueous solution contains one or more phosphating accelerators selected from: 
 0.05 to 2 g/l m-nitrobenzene sulfonate ions,  
 0.1 to 10 g/l hydroxylamine in free or bound form,  
 0.05 to 2 g/l m-nitrobenzoate ions,  
 0.05 to 2 g/l p-nitrophenol,  
 1 to 70 mg/l hydrogen peroxide in free or bound form,  
 0.05 to 10 g/l organic N-oxides  
 0.1 to 3 g/l nitroguanidine  
 1 to 500 mg/l nitrite ions  
 0.5 to 5 g/l chlorate ions.  
 
     
     
         12 . A process as claimed in one or more of  claims 1  to  11  wherein the aqueous solution is free from chromium.  
     
     
         13 . A process as claimed in one or more of  claims 1  to  12  wherein the vehicle bodies or domestic appliances have surfaces of at least two materials selected from zinc, aluminum, magnesium, alloys of these metals with one another or with other alloying elements.  
     
     
         14 . A process as claimed in one or more of  claims 1  to  13  wherein, after passivation, the vehicle bodies or domestic appliances are coated with a dipping paint suitable for electrodeposition or with a powder coating.