Zinc phosphating with integrated subsequent passivation

Abstract

A process for the phosphatizing of metal surfaces composed of steel, zinc-coated steel or steel coated with zinc alloy, of aluminum and/or of aluminum-magnesium alloys, characterized in that the phosphatizing solution contains: 0.2 to 3 g/l of zinc ions, 3 to 50 g/l of phosphate ions, calculated as PO 4 , 0.001 to 4 g/l of manganese ions, 0.001 to 0.5 g/l of one or more polymers selected from polyethers, polycarboxylates, polymeric phosphonic acids, polymeric phosphinocarboxylic acids and nitrogen-containing organic polymers and one or more accelerators. Preferred polymers are poly(vinylphenol) derivatives containing amino groups.

1 . Process for the phosphatizing of metal surfaces composed of steel, zinc-coated steel or steel coated with zinc alloy, of aluminum and/or of aluminum-magnesium alloys, whereby the metal surfaces, by means of spraying or dipping for a period of between 3 seconds and 8 minutes, are brought into contact with a zinc-containing phosphatizing solution, characterized in that the phosphatizing solution contains: 
 0.2 to 3 g/l of zinc ions;    3 to 50 g/l of phosphate ions, calculated as PO 4 ;    0.001 to 4 g/l of manganese ions;    0.001 to 0.5 g/l of one or more polymers selected from polycarboxylates, polymeric phosphonic acids, polymeric phosphinocarboxylic acids, nitrogen-containing organic polymers and poly-4-vinylphenol compounds corresponding to the general formula I:                          wherein n is a number between 5 and 100, x independently of one another denote hydrogen and/or CRR 1 OH groups, in which R and R 1  denote hydrogen, aliphatic and/or aromatic groups having 1 to 12 carbon atoms; and    one or more accelerators selected from: 
 0.05 to 2 g/l of m-nitrobenzoate ions;  
 0.05 to 2 g/l of p-nitrophenol;  
 0.1 to 10 g/l of hydroxylamine in free or bound form;  
 0.1 to 10 g/l of a reducing sugar,  
 the phosphatizing solution containing not more than 0.5 g/l nitrate and the weight ratio of phosphate ions to zinc ions being within the range between 3.7 and 30.  
   
     
     
         2 . Process according to  claim 1 , characterized in that the phosphatizing solution contains in addition from 1 to 50 mg/l of nickel ions and/or from 5 to 100 mg/l of cobalt ions.  
     
     
         3 . Process according to one or both of claims  1  and  2 , characterized in that the phosphatizing solution contains in addition from 0.2 to 1.5 g/l of lithium ions.  
     
     
         4 . Process according to one or more of  claims 1  to  3 , characterized in that the phosphatizing solution contains in addition fluoride in quantities of up to 2.5 g/l of total fluoride, whereof up to 1 g/l is free fluoride, in each case calculated as F − .  
     
     
         5 . Process according to one or more of  claims 1  to  4 , characterized in that the phosphatizing solution contains as accelerator from 0.1 to 10 g/l of hydroxylamine in free or bound form.  
     
     
         6 . Process according to one or more of  claims 1  to  5 , characterized in that the phosphatizing solution contains the organic polymers in a concentration of between 0.01 and 0.1 g/l.  
     
     
         7 . Process according to one or more of  claims 1  to  6 , characterized in that the organic polymers are selected from homopolymeric or copolymeric compounds which contain amino groups and which contain or consist of structural units corresponding to the general formula (II):  
       
         
           
           
               
               
           
         
       
       and hydrolysis products thereof, wherein R 1  and R 2  are identical with one another or different and can represent hydrogen or alkyl having 1 to 6 carbon atoms.  
     
     
         8 . Process according to one or more of  claims 1  to  6 , characterized in that the organic polymers are selected from homopolymeric or copolymeric compounds which contain amino groups and include at least one polymer, which is selected from the group consisting of a), b), c) or d), wherein: a) comprises a polymeric material which has at least one unit corresponding to the formula:  
       
         
           
           
               
               
           
         
       
       wherein:  
       R 1  to R 3 , independently for each of the units, are selected from the group comprising 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 comprising 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 Y 1 , Y 2 , Y 3  or Y 4  of the homopolymeric or copolymeric compound or material must be Z;  
       R 5  to R 12 , independently for each of the units, are selected from the group comprising hydrogen, an alkyl, aryl, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group; R 12  can also be —O (−)  or —OH;  
       W 1 , independently for each of the units, is selected from the group comprising hydrogen, an acyl group, an acetyl group, a benzoyl group; 3-allyloxy-2-hydroxy-propyl; 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 of the same;  
       b) comprises a polymeric material having at least one unit corresponding to the formula:  
       
         
           
           
               
               
           
         
       
       wherein:  
       R 1  to R 2 , independently for each of the units, are selected from the group comprising 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 comprising 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 Y 1 , Y 2 , or Y 3  of the end product must be Z; R 4  to R 12 , independently for each of the units, are selected from the group comprising hydrogen, an alkyl, aryl, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group; R 12  can also be —O (−)  or —OH;  
       W 2 , independently for each of the units, is selected from the group comprising hydrogen, an acyl group, an acetyl group, 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 of the same;  
       c) comprises: a copolymeric material, wherein at least a part of the copolymer has the structure:  
       
         
           
           
               
               
           
         
       
       and at least a fraction of the said part is polymerized with one or more monomers which, independently for each unit, are selected from the group comprising 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, tert-butylaminoethyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, n-butyl vinyl ether, tert-butyl vinyl ether, m-chlorostyrene, o-chlorostyrene, p-chlorostyrene, n-decyl methacrylate, N,N-diallylmelamine, N,N-di-n-butylacrylamide, di-n-butyl itaconate, di-n-butyl maleate, diethylaminoethyl methacrylate, diethylene glycol monovinyl ether, diethyl fumarate, diethyl itaconate, diethylvinyl 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-ethylmethacrylamide, ethyl methacrylate, ethyl vinyl ether, 5-ethyl-2-vinyl pyridine, 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-alkyloxymethylacrylamide, N-alkyloxymethylmethacrylamide, N-vinylcaprolactam, methyl acrylate, N-methylmethacrylamide, α-methylstyrene, m-methylstyrene, o-methylstyrene, p-methylstyrene, 2-methyl-5-vinylpyridine, n-propyl methacrylate, sodium p-styrenesulfonate, stearyl methacrylate, styrene, p-styrenesulfonic acid, p-styrene sulfonamide, vinyl bromide, 9-vinylcarbazole, vinyl chloride, vinylidene chloride, 1-vinylnaphthalene, 2-vinylnaphthalene, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyridine-N-oxide, 4-vinylpyrimidine, N-vinylpyrrolidone; and W 1  , Y 1  to Y 4  and R 1  to R 3  are as described under a);  
       (d) comprises a condensation polymer made from the polymeric materials (a), (b) or (c), a condensable form of (a), (b), (c) or a mixture of the same being condensed with a second compound selected from the group consisting of phenols, tannins, novolak resins, lignin compounds, together with aldehydes, ketones or mixtures thereof, in order to prepare a condensation resin product, the condensation resin product forming, by the addition of “Z” to at least a part of itself by further reaction of the resin product with 1) an aldehyde or ketone, (2) a secondary amine, a final adduct which may react with an acid.  
     
     
         9 . Process according to  claim 8 , characterized in that at least a fraction of the groups Z of the organic polymer possesses a polyhydroxyalkylamine functionality which originates from the condensation of an amine or of ammonia with a ketose or aldose which has 3 to 8 carbon atoms.  
     
     
         10 . Process according to  claim 8 , characterized in that the organic polymer is a condensation product of a polyvinylphenol, having a molar mass within the range of 1,000 to 10,000, with formaldehyde or paraformaldehyde and with a secondary organic amine.  
     
     
         11 . Process according to  claim 10 , characterized in that the secondary organic amine is selected from methylethanolamine and N-methylglucamine.  
     
     
         12 . Process according to one or more of  claims 1  to  8 , characterized in that the organic polymers are selected from substituted polyalkylene derivatives:  
       
         
           
           
               
               
           
         
       
       wherein:  
       R 1 , R 2 , R 3  independently of one another can be hydrogen or a methyl or ethyl group;  
       x denotes 1, 2, 3 or 4; and  
       Y denotes a substituent which contains at least one nitrogen atom, which is incorporated into an alkylamino group or into a mononuclear or polynuclear saturated or unsaturated heterocyclic compound.  
     
     
         13 . Process according to  claim 12 , characterized in that R 1 , R 2 , R 3  each denote hydrogen and that x equals 1.  
     
     
         14 . Process according to  claim 12  or  13 , characterized in that the organic polymers contain one or more of the following structural units:  
       
         
           
           
               
               
           
         
       
     
     
         15 . Process according to one or more of  claims 1  to  6 , characterized in that the organic polymers are polymeric sugar derivatives containing amino groups.  
     
     
         16 . Process according to  claim 15 , characterized in that the polymeric sugar derivatives contain the following structural groups: