DE19621184A1 - Zinc phosphating with integrated post-passivation - Google Patents

Abstract

A process for phosphating the surface of steel, galvanised or alloy-galvanised steel, aluminium and/or aluminium-magnesium alloys, in which the phosphating solution contains 0.2 to 3 g/l zinc ions, 3 to 50 g/l phosphate ions calculated as PO4, 0.001 to 4 g/l manganese ions, 0.001 to 0.5 g/l of one or more polymers selected from among polyethers, polycarboxylates, polymeric phosphonic acids, polymeric phosphino carboxylic acids and nitrogen-containing organic polymers and one or more accelerators. Preferred polymers are amino group-containing poly(vinyl phenol) derivatives.

Description

The invention relates to processes for phosphating metal surfaces aqueous, acid phosphating solutions, the zinc, manganese and phosphate ions so such as containing up to 0.5 g / l of organic polymers. The invention further relates to the application of such methods as a pretreatment of the metal surfaces for a subsequent painting, in particular an electrocoating or a Powder coating. The method can be used to treat surfaces made of steel, galvanized or alloy galvanized steel, aluminum, aluminum Magnesium alloys, aluminized or alloy-aluminized steel and avoids the passivating rinsing that was previously required.

The phosphating of metals pursues the goal of being firmly on the metal surface to produce overgrown metal phosphate layers that are already the corrosi Improve onsistance and in connection with paints or other organi coatings to a significant increase in paint adhesion and Resistance to infiltration when exposed to corrosion contribute. Such Phosphating processes have been known for a long time. For pre-treatment before Painting, especially electrocoating, are particularly suitable  Low-zinc phosphating processes in which the phosphating solutions are compared as low levels of zinc ions of z. B. 0.5 to 2 g / l. An essential The parameter in these low-zinc phosphating baths is the weight ratio nis phosphate ions to zinc ions, which is usually in the range greater than 8 and Can take values up to 30.

It has been shown that by using other polyvalent cations in the zinc phosphating baths, phosphate layers with significantly improved corrosion onsschutz- and paint adhesion properties can be trained. Example find low-zinc processes with the addition of z. B. 0.5 to 1.5 g / l Manganio NEN and z. B. 0.3 to 2.0 g / l of nickel ions as a so-called trication method Preparation of metal surfaces for painting, for example for the ka traditional electrodeposition coating of car bodies, wide application.

Since nickel and the alternative cobalt are also made from toxicological and wastewater technology are classified as critical, there is a need for Phosphating processes that have a similar level of performance as the trication Have processes, but with much lower bath concentrations of Nickel and / or cobalt and preferably manage without these two metals.

From DE-A-20 49 350 a phosphating solution is known which is an essential loading ingredients 3 to 20 g / l phosphate ions, 0.5 to 3 g / l zinc ions, 0.003 to 0.7 g / l Cobalt ions or 0.003 to 0.04 g / l copper ions or preferably 0.05 to 3 g / l Nickel ions, 1 to 8 g / l magnesium ions, 0.01 to 0.25 g / l nitrite ions and 0.1 to 3 g / l Contains fluorine ions and / or 2 to 30 g / l chlorine ions. This procedure describes accordingly a zinc-magnesium phosphating, the phosphating solution to additionally contains one of the ions cobalt, copper or preferably nickel. One of the like zinc-magnesium phosphating could not prevail in technology Zen.  

EP-B-18 841 describes a chlorate-nitrite-accelerated zinc phosphating solution solution containing, inter alia, 0.4 to 1 g / l zinc ions, 5 to 40 g / l phosphate ions and optionally at least 0.2 g / l, preferably 0.2 to 2 g / l, of one or more Ions selected from nickel, cobalt, calcium and manganese. Accordingly, the optional manganese, nickel or cobalt content at least 0.2 g / l. In the execution Examples of nickel are given as 0.53 and 1.33 g / l.

EP-A-459 541 describes phosphating solutions which are essentially free of In addition to zinc and phosphate, nickel is 0.2 to 4 g / l manganese and 1 to 30 mg / l Copper included. DE-A-42 10 513 describes nickel-free phosphating solutions gene known that in addition to zinc and phosphate 0.5 to 25 mg / l copper ions and as Accelerators contain hydroxylamine. These optionally contain phosphating solutions solutions also 0.15 to 5 g / l manganese.

The German patent application DE 196 06 017.6 describes a heavy metal reduction graced phosphating solution containing 0.2 to 3 g / l zinc ions, 1 to 150 mg / l manganese ions and contains 1 to 30 mg / l copper ions. This phosphating solution can optionally be used up to contain up to 50 mg / l nickel ions and up to 100 mg / l cobalt ions. Another optional components are lithium ions in amounts between 0.2 and 1.5 g / l.

The German patent application DE 195 38 778.3 describes the control of the Layer weight of phosphate layers through the use of hydroxylamine as accelerator: the use of hydroxylamine and / or its verbin One way to influence the shape of the phosphate crystals is from a number of Disclosure known. EP-A-3 15 059 gives the as a special effect Use of hydroxylamine in phosphating baths indicates the fact that Then steel the phosphate crystals in a desired column or kno ten-like form arise when the zinc concentration in the phosphating bath  Low-zinc process exceeds usual range. This makes it possible to Phosphating baths with zinc concentrations up to 2 g / l and with Ge weight ratios of phosphate to zinc down to 3.7. About advantageous Te cation combinations of these phosphating baths are no further statements made, in the patent examples, however, nickel is used in all cases. Nitrates and nitric acid are also used in the patent examples, too if in the description depends on the presence of nitrate in larger quantities is advised. The required hydroxylamine concentration is 0.5 to 50 g / l, preferably 1 to 10 g / l specified. The maximum concentration at Hydroxylammonium sulfate in the patent examples is 5 g / l, from which a Ge hold of hydroxylamine calculated from 2.08 g / l. (Contains hydroxylammonium sulfate 41.5 wt% hydroxylamine). The phosphating solution is sprayed on applied the steel surfaces. The scripture does not mention the problems Immersion processes leading to phosphate layers with significantly higher layer weights lead as they are undesirable as a basis for subsequent painting.

WO 93/03 198 teaches the use of hydroxylamine as an accelerator in Trication phosphating baths with zinc contents between 0.5 and 2 g / l and nickel and Manganese contents of 0.2 to 1.5 g / l each, with certain Ge weight ratios between zinc and the other divalent cations are. These baths also contain 1 to 2.5 g / l of a "hydroxylamine Accelerator ", among which, according to the description, salts of hydroxylamine are preferred wise hydroxylammonium sulfate are to be understood. If you add up this information free hydroxylamine, so hydroxylamine contents between 0.42 and 1.04 g / l intended.

To improve the corrosion protection caused by the phosphate layer he usually follows a so-called passivating rinse in technology Called post-passivation. Treatment baths containing chromic acid are still suitable for this  widespread. However, for reasons of work and environmental protection The tendency of these chromium-containing passivation baths to be replaced by chrome-free treatment baths to replace. For this purpose, for example, organic-reactive bathroom solutions with com known plexifying substituted poly (vinylphenols). For example such compounds are described in DE-C-31 46 265. Especially we Kung full polymers of this type contain amine substituents and can by a Mannich reaction of poly (vinylphenols) with aldehydes and organic amines be obtained. Such polymers are described, for example, in EP-B-91 166, EP-B-319 016 and EP-B-319 017. Polymers of this type are also used in Framework used in the present invention, so that the content of the above four documents mentioned expressly on the content of the disclosure of the present the patent application is made. Furthermore, the passivating Rinse solutions containing amino group-containing polymers in which the amine group directly to the polymer chain without the interposition of an aromatic ring te is bound. Such polymers within the scope of the present invention can also be used are described in DE-A-44 09 306.

In conjunction with a passivating rinse, the currently used low-zinc phosphating baths meet the corrosion protection requirements that tomobilbau be put. However, this sequence of processes has the disadvantage that the passivating rinsing represents a separate treatment level, which the produc tion time and increases the space requirement of the pretreatment line.

The invention has for its object to provide a phosphating solution to provide, which meets the corrosion protection requirements of the automotive industry and in which the passivating rinse can be omitted. This will reduce the space requirement of the pretreatment line and, if applicable, the production time.  

It is already known from the literature to add phosphating solutions to polyacrylic acids Zen. For example, the article by J.I. Wragg, J.E. Chamberlain, L. Chann, H.W. White, T. Sugama, and S. Manalis: "Characterization of Polyacrylic Acid modified Zinc Phosphate Crystal Conversion Coatings ", Journal of Applied Polymer Science, Vol. 50, 917-928 (1993). Here, however, were model-like Zinc phosphating solutions are investigated that differ significantly from those currently in practice Differences used: They contain higher levels of zinc, on the other hand they are missing the widely used manganese and, as a rule, the Be currently used accelerator. They are therefore not a model for those in the context of the present inven low-zinc phosphating solutions.

The object is achieved by a method for phosphating metal surfaces made of steel, galvanized or galvanized steel and / or aluminum, in which the metal surfaces are in contact with a zinc-containing phosphating solution by spraying or dipping for a time between 3 seconds and 8 minutes brings, characterized in that the phosphating solution
0.2 to 3 g / l zinc ions
3 to 50 g / l phosphate ions, calculated as PO₄,
0.001 to 4 g / l manganese ions,
0.001 to 0.5 g / l of one or more polymers selected from polyethers, polycar boxylates, polymeric phosphonic acids, polymeric phosphinocarboxylic acids and nitrogen-containing organic polymers and
one or more accelerators selected
0.3 to 4 g / l chlorate ions,
0.01 to 0.2 g / l nitrite ions,
0.05 to 2 g / l m-nitrobenzenesulfonate ions,
0.05 to 2 g / l m-nitrobenzoate ions,
0.05 to 2 g / l p-nitrophenol,
0.005 to 0.15 g / l hydrogen peroxide in free or bound form,
0.1 to 10 g / l hydroxylamine in free or bound form,
0.1 to 10 g / l of a reducing sugar
contains.

The zinc concentration is preferably in the range between about 0.3 and about 2 g / l and in particular between about 0.8 and about 1.6 g / l. Zinc levels above 1.6 g / l, for example between 2 and 3 g / l bring only small amounts for the process Advantages, but can also increase the amount of sludge in the phosphating bath. Such zinc contents can occur in a working phosphating bath, if in the phosphating of galvanized surfaces through the removal of pickling The zinc gets into the phosphating bath. Concentrated nickel and / or cobalt ions tration range from about 1 to about 50 mg / l for nickel and about 5 to about 100 mg / l for cobalt improve in conjunction with the lowest possible Ni content of no more than about 0.5 g / l against corrosion protection and paint adhesion About phosphating baths that do not contain nickel or cobalt or that contain a Ni tread content of more than 0.5 g / l. This is a cheap compromise between the performance of the phosphating baths on the one hand and the requirements on the other hand, the wastewater treatment of the rinsing water is achieved.

In the case of phosphate baths reduced in heavy metals, the manganese content can be in the range from about 0.001 to about 0.2 g / l. Otherwise, manganese levels are around 0.5 up to about 1.5 g / l usual.

From the German patent application with the file number 195 00 927.4 be knows that lithium ions in the amount range from about 0.2 to about 1.5 g / l with Improve the corrosion protection achievable with zinc phosphating baths. Lithium levels in the amount range from 0.2 to about 1.5 g / l and in particular from about 0.4 to about  1 g / l also have an effect in the phosphating process according to the invention with inte free passivation favorably on the achieved corrosion protection.

Except for the cations mentioned above, which are built into the phosphate layer or at least the crystal growth of the phosphate layer be positive influence, the phosphating baths usually contain sodium, potassium and / or Ammonium ions to adjust the free acid. The concept of free acid is familiar to the expert in the phosphating field. The one chosen in this document The method for determining free acid and total acid is shown in the example section specified. Free acid and total acid constitute an important control parameter ter for phosphating baths, since they have a great influence on the layer weight to have. Free acid values between 0 and 1.5 points for partial phosphating, with band phosphating up to 2.5 points and the total acidity between about 15 and about 30 points are in the usual technical range and are in the frame this invention.

It is the case with phosphating baths that should be suitable for different substrates become common, free and / or complex bound fluoride in amounts up to 2.5 g / l Total fluoride, of which up to 1 g / l free fluoride should be added. The presence such amounts of fluoride is also suitable for the phosphating baths according to the invention Advantage. In the absence of fluoride, the aluminum content of the bath should be 3 mg / l do not exceed. In the presence of fluoride, the complex bil tolerated higher Al contents, provided the concentration of the uncomplexed Al does not exceed 3 mg / l. The use of fluoride-containing baths is therefore an advantage adheres if the surfaces to be phosphated are at least partially made of aluminum to exist or contain aluminum. In these cases it is cheap, no com plexbound, but only free fluoride, preferably in concentrations in Range 0.5 to 1.0 g / l.  

For the phosphating of zinc surfaces, it would not be absolutely necessary that the phosphating baths contain so-called accelerators. For phosphatia tion of steel surfaces, however, it is necessary that the phosphating solution contains one or more accelerators. Such accelerators are in the state of the art Technology known as components of zinc phosphating baths. Below are Substances understood that by acid pickling on the metal surface Bind the resulting hydrogen chemically by reducing it itself will. Oxidizing accelerators continue to have the effect of Stain attack on steel surfaces released iron (II) ions to the trivalent level to oxidize so that they can precipitate as iron (III) phosphate.

The phosphating baths according to the invention can contain one or more of the following components as accelerators:
0.3 to 4 g / l chlorate ions,
0.01 to 0.2 g / l nitrite ions,
0.05 to 2 g / l m-nitrobenzenesulfonate ions,
0.05 to 2 g / l m-nitrobenzoate ions,
0.05 to 2 g / l p-nitrophenol,
0.005 to 0.15 g / l hydrogen peroxide in free or bound form,
0.1 to 10 g / l hydroxylamine in free or bound form,
0.1 to 10 g / l of a reducing sugar.

When phosphating galvanized steel, it is necessary that the phospha animal solution contains as little nitrate as possible. Nitrate concentrations of 0.5 g / l should should not be exceeded, since at higher nitrate concentrations there is a risk of so-called "speck formation" exists. These are white, crater-like defects in the phosphate layer meant. In addition, the paint adhesion is galvanized Surfaces affected.  

The use of nitrite as an accelerator leads in particular to steel surfaces for technically satisfactory results. For the sake of Ar occupational safety (danger of developing nitrous gases), however, it is em Recommended to avoid nitrite as an accelerator. For phosphating galvanized surfaces, this is advisable for technical reasons as well Nitrite can form nitrate, which, as explained above, is a problem of specks formation and lead to reduced paint adhesion on zinc.

For reasons of environmental friendliness is hydrogen peroxide, for technical reasons Because of the simplified formulation options for replenishment solutions Hydroxylamine is particularly preferred as an accelerator. The common use However, it is not advisable to use these two accelerators since hydroxylamine is from Hydrogen peroxide is decomposed. If you put hydrogen peroxide in free or ge bound form as an accelerator, so are concentrations of 0.005 to 0.02 g / l Hydrogen peroxide is particularly preferred. The hydrogen peroxide be added to the phosphating solution as such. However, it is also possible To use hydrogen peroxide in bound form as compounds that in Provide phosphating bath hydrogen peroxide by hydrolysis reactions. Examples such compounds are persalts such as perborates, percarbonates, or peroxosulfates Peroxodisulfates. Ionic per come as further sources of hydrogen peroxide oxides such as alkali metal peroxides into consideration. A preferred out leadership form of the invention is that in the phosphating in the Tauchver drive a combination of chlorate ions and hydrogen peroxide is used. In this embodiment, the concentration of chlorate can be, for example, in Range of 2 to 4 g / l, the concentration of hydrogen peroxide in the range of 10 to 50 ppm.

The use of reducing sugar as an accelerator is known from US-A-5 378 292 known. You can within the scope of the present invention in amounts between  about 0.01 and about 10 g / l, preferably in amounts between about 0.5 and about 2.5 g / l can be used. Examples of such sugars are galactose, mannose and especially glucose (dextrose).

Another preferred embodiment of the invention is as Be to use accelerator hydroxylamine. Hydroxylamine can be used as a free base, as Hydroxylamine complex, as oxime, which is a condensation product of hydroxyla represents min with a ketone, or in the form of hydroxylammonium salts be set. Add free hydroxylamine to the phosphating bath or a Phos phatierbad concentrate too, because of the acidic nature of these solutions largely present as a hydroxylammonium cation. When used as Hydroxylammonium salt, the sulfates and the phosphates are particularly suitable. In the case of the phosphates, the acid salts are due to the better solubility prefers. Hydroxylamine or its compounds are in the phosphating bath such amounts added that the calculated concentration of the free hydroxyl amine is between 0.1 and 10 g / l, preferably between 0.3 and 5 g / l. It is it preferred that the phosphating baths be the only accelerator hydroxylamine, at most together with a maximum of 0.5 g / l nitrate. Accordingly, in one preferred embodiment used phosphating baths that none of the other known accelerators such as nitrite, oxo anions of halogens, Contain peroxides or nitrobenzenesulfonate. Reduce as a positive side effect Hydroxylamine concentrations above about 1.5 g / l pose the risk of rust at insufficiently flooded areas of the components to be phosphated.

When the phosphating process is used on steel surfaces, iron goes in Form of iron (II) ions in solution. If the phosphating baths according to the invention it does not contain any substances that have an oxidizing effect on iron (II) divalent iron only in the trivalent state as a result of air oxidation over so that it can precipitate as iron (III) phosphate. This is for example at  the use of hydroxylamine. Therefore, in the phospha animal baths build iron (II) levels that are significantly higher than the levels Baths containing oxidizing agents. In this sense, iron (II) - Concentrations up to 50 ppm normal, but in the short term in the production process Values up to 500 ppm can also occur. For the phospha according to the invention Such iron (II) concentrations are not harmful to animal processes. When approaching in In hard water, the phosphating baths can continue to use the hardening agent cations Mg (II) and Ca (II) contained in a total concentration of up to 7 mmol / l. Mg (II) or Ca (II) can also be added to the phosphating bath in amounts of up to 2.5 g / l be set.

The weight ratio of phosphate ions to zinc ions in the phosphating baths can vary within a wide range, provided it is in the range between 3.7 and 30. A weight ratio between 10 and 20 is particularly preferred. For the indication of the phosphate concentration, the total phosphorus content of the phosphating bath is considered to be present in the form of phosphate ions PO₄ ^3- . Accordingly, the known fact that the pH values of the phosphating baths, which are usually in the range from about 3 to about 3.6, only a very small part of the phosphate is actually in the form of the triple negative charged anions. At these pH values, it is rather to be expected that the phosphate is present primarily as a single negatively charged dihydrogen phosphate anion, together with smaller amounts of undisociated phosphoric acid and double negatively charged hydrogen phosphate anions.

The organic polymers to be used according to the invention preferably have Molar masses (can be determined, for example, by gel permeation chromatography) in Range from about 500 to about 50,000, especially from about 800 to about 20,000 on.  

The phosphating baths preferably contain the organic polymers in one Concentration between about 0.01 and about 0.1 g / l. At lower concentrations the desired passivating effect occurs less and less. Higher concentrations trations no longer significantly increase the effect and are therefore increasing uneconomical.

The polymers which can be used in the sense of the invention can vary belong to chemical groups. However, they have in common that they either in the polymer chain or in side groups oxygen atoms and / or nitrogen atoms carry. The simplest polymers of this type are polyalkylene glycols, for example Polyethylene or polypropylene glycols, which preferably have a molecular weight in the loading range from 500 to 10,000. Polymeric carboxylic acids are also suitable such as homo- or copolymers of acrylic acid, methacrylic acid and Maleic acid. Polymeric phosphonic acids or polymers are also suitable Phosphinocarboxylic acids. An example is a polyphosphinocarboxylic acid re which can be regarded as an acrylic acid-sodium hypophosphite copolymer and is commercially available as "Belclene® 500" from FMC Corporation, Great Britain.

Furthermore, the organic polymers can be selected from amino groups containing homo- or copolymer compounds, the Structural units of the general formula (I)

and their hydrolysis products contain or consist thereof, wherein R¹ and R² are the same or different from each other and for hydrogen or alkyl with 1 to  6 carbon atoms, e.g. B. methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, amyl, n-hexyl, isohexyl or diclohexyl can be.

A detailed list of polymers of this type can be found in DE-A-44 09 306 are hereby expressly taken as part of this disclosure is made. Specific examples are hydrolysis products from Homo- and Copo lymeren of N-vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N-vinyl N-methylacetamide, N-vinyl-N-ethylacetamide, N-vinyl propionamide and N-vinyl N-methylpropionamide, with N-vinylformamide being very easy to hydrolyze is preferred. Comonomers are monoethylenically unsaturated carboxylic acids ren with 3 to 8 carbon atoms and the water-soluble salts of these monomers in Be dress.

Furthermore, the organic polymers can be selected from poly-4-vinyl phenol compounds of the general formula (II),

in which
n is a number between 5 and 100,
x are independently hydrogen and / or CRR₁OH groups, in which R and R₁ are hydrogen, aliphatic and / or aromatic radicals having 1 to 12 carbon atoms.

As separate rinse solutions, these polymers are described in DE-C-31 46 265 wrote. According to this teaching, such poly-4-vinyl are in particular phenol compounds are suitable in which at least 1 × = CH₂OH. On Processes for their production is specified in the document mentioned.

Organic polymers that are selected are particularly preferably used from amino group-containing homo- or copolymer compounds at least one polymer selected from the group consisting of a), b), c) or d), in which:

• a) a polymer material comprising at least one unit of the formula: in which:
  R₁ to R₃ are independently selected for each of the units 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;
  Y₁ to Y₄ are independently selected for each of the units from the group consisting of hydrogen, -CR₁₁R₅OR₆, -CH₂Cl or an alkyl or aryl group having 1 to 18 carbon atoms or Z: is, however, at least a fraction of Y₁, Y₂, Y₃ or Y₄ of the homo- or copolymer compound or material Z must be: R₅ to R₁₂ are independently selected for each of the units from the group consisting of hydrogen; an alkyl, ary, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group;
  R₁₂ can also be -O ^(-1) or -OH;
  W₁ is independently selected for each of the units from the group consisting of hydrogen; an acyl, an acetyl, a benzoyl group; 3-allyloxy-2-hydroxy propyl; 3-benzyloxy-2-hydroxypropyl; 3-butoxy-2-hydroxypropyl; 3-alkyloxy-2-hydroxy-propyl-; 2-hydroxyoctyl; 2-hydroxyalkyl-; 2-hydroxy-2-phenyl ethyl-; 2-hydroxy-2-alkylphenylethyl-; Benzyl; Methyl-; Ethyl; Propyl; Alkyl; Allyl; Alkylbenzyl; Haloalkyl-; Haloalkenyl; 2-chloropropenyl; Sodium; Potassium; Tetraaryl ammonium; Tetraalkylammonium; Tetraalkylphosphonium; Tetra arylphosphonium or a condensation product of ethylene oxide, propylene oxide or a mixture or a copolymer thereof;
• b) includes:
  a polymer material with at least one unit of the formula: wherein:
  R₁ to R₂ are independently selected for each of the units 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;
  Y₁ to Y₃ are independently selected for each of the units from the group consisting of hydrogen; -CR₄R₅OR₆, -CH₂Cl or an alkyl or aryl group with 1 to 18 carbon atoms or Z: is, however, at least one fraction of the Y₁, Y₂ or Y₃ of the final compound must be Z; R₄ to R₁₂ are independently selected for each of the units from the group consisting of hydrogen; an alkyl, aryl, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group; R₁₂ can also be -O ^(-1) or -OH;
  W₂ is independently selected for each of the units from the group consisting of hydrogen, an acyl, an acetyl, a benzoyl group; 3-allyloxy-2-hydroxy propyl; 3-benzyloxy-2-hydroxy-propyl-; 3-alkylbenzyloxy-2-hydroxy propyl-; 3-phenoxy-2-hydroxypropyl; 3-alkylphenoxy-2-hydroxypropyl; 3-butoxy-2-hydroxypropyl; 3-alkyloxy-2-hydroxypropyl; 2-hydroxyoctyl; 2-hydroxyl alkyl-; 2-hydroxy-2-phenylethyl-; 2-hydroxy-2-alkylphenylethyl-; Ben cyl-; Methyl-; Ethyl; Propyl; Alkyl; Allyl; Alkylbenzyl; Haloalkyl-; Haloal kenyl-; 2-chloropropenyl or a condensation product of ethylene oxide, propylene oxide or a mixture thereof;
• c) includes:
  a copolymer material wherein at least a portion of the copolymer has the structure has and at least one fraction of said part is polymerized with one or more monomers which are independently selected 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, 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-diallymelamine, 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, vinyl phosphonic acid, diisobutyl maleate, diisoproyl itaconate, diisopropyl maleate, di methyl fumarate, dimethyl itaconate, dimethylma leat, di-n-nonyl fumarate, di-n-nonyl maleate, dioctyl fumarate, di-n-octyl itaconate, di-n-propyl itaconate, N-dode cyl vinyl ether, acid ethyl fumarate, acid ethyl maleate, ethyl acrylate, ethyl cynate, N-ethyl methacrylamide, ethyl , Ethyl vinyl ether, 5-ethyl-2-vinyl pyridine, 5-ethyl-2-vinyl pyridine-1-oxide, glycidyl acrylate, glycidyl methacrylate, n-hexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, isobutyl methacrylate, isobutyl vinyl ether, isoprene, isopro, isopro , Itaconic acid, lauryl methacrylate, methacrylamide, methacrylic acid, methacrylonitrile, N-methylolacrylamide, N-methylol methacrylamide, N-isobutoxymethylacrylamide, N-isobutoxymethyl methacrylamide, N-alkyl oxymethylacrylamide, N-alkyloxymethyl methacrylamide, N-vinylcaprolatamide, methyl-methylacrylamide, methyl-methylacrylamide, methyl-methacrylate, , m-methyl styrene, o-methyl styrene, p-methyl styrene, 2-methyl-5-vinyl pyridine, n-propyl methacrylate, sodium p-styrene sulfonate, stearyl methacrylate, styrene, p-styrene sulfones acid, p-styrene sulfonamide, vinyl bromide, 9-vinyl carbazole, vinyl chloride, vinylidene chloride, 1-vinyl naphthalene, 2-vinyl naphthalene, 2-vinyl pyridine, 4-vinyl pyridine, 2-vinyl pyridine-N-oxide, 4-vinyl pyrimidine, N-vinyl pyrrolidone; and W₁, Y₁-Y₄ and R₁-R₃ are as described under a);
• d) comprises a condensation polymer composed of the polymeric materials a), b) or c), wherein a condensable form of a), b), c) or a mixture thereof with a second compound is condensed, which is selected from the group be consisting of phenols, tannins, novolak resins, lignin compounds aldehydes, ketones or their mixtures to form a condensation resin To produce product, the condensation resin product by adding "Z" to at least a part thereof, by reaction of the resin product with 1) ei nem aldehyde or ketone 2) then reacted a secondary amine, under Formation of a final adduct that can react with an acid.

Processes for the production of such polymers are in the printing already mentioned publications EP-B-3 19 016 and EP-B-3 19 017. Polymers of this type can are obtained from Henkel Corporation, Parker Amchen Division, USA under the trade names Parcolene® 95C, Deoxylyte® 90A, 95A, 95AT, 100NC and TD-1355-CW.

Polymers in which at least one is preferred are particularly preferred Fraction of groups Z of the organic polymer a polyhydroxyalkylamine Has functionality resulting from the condensation of an amine or ammonia comes with a ketosis or aldose containing 3 to 8 carbon atoms. There the condensation products can, if desired, be reduced to the amine be that.

Further examples of such polymers are condensation products of a Po lyvinylphenols with formaldehyde or paraformaldehyde and with a secondary organic amine. It is preferable to use polyvinylphenols with a Molecular mass in the range from about 1000 to about 10,000. Here are particular preferred condensation products in which the secondary organic Amine is selected from methylethanolamine and N-methylglucamine.  

The organic polymers are in the specified concentration ranges Phosphating baths are stable and do not lead to precipitation. They don't show either For example, they do not lead to a negative effect on the layer formation Passivation phenomena on the metal surface, which indicate the growth of the Phos could hinder phat crystals.

Furthermore, the organic polymers can be selected from substituted Po lyalkylene derivatives with the structural units

where R¹, R², R³ can independently be hydrogen or a methyl or ethyl group,
x = 1, 2, 3 or 4 means and
Y represents a substituent which contains at least one nitrogen atom which is incorporated in an alkylamine group or in a mono- or polynuclear saturated or unsaturated heterocycle.

Those polymers are preferred in which R¹, R², R³ are each hydrogen mean. Preferably x = 1. Accordingly, polymers are particularly preferred, which are substituted polyethylenes. Organic polymers are special preferred, which contain one or more of the following structural units:

In a further preferred embodiment, the organic polymers polymeric sugar derivatives containing amino groups. An example of this are chito sane, which may include the following assembly:

For all nitrogen-containing organic polymers it applies that at pH values the Phosphating solution is protonated at least part of the nitrogen atoms and therefore carries a positive charge.

Phosphating baths are usually sold in the form of aqueous concentrates, which are adjusted on site to the application concentrations by adding water. For reasons of stability, these concentrates may contain an excess of free phosphoric acid, so that when diluted to bath concentrations, the value of the free acid is initially too high or the pH is too low. By adding alkalis such as sodium hydroxide, sodium carbonate or ammonia, the value of the free acid is reduced to the desired range. Furthermore, it is known that the free acid content during use of the phosphating baths can increase over time due to the consumption of the layer-forming cations and, if appropriate, through decomposition reactions of the accelerator. In these cases it is necessary to adjust the value of the free acid to the desired range from time to time by adding alkalis. This means that the contents of the phosphating baths in alkali metal or ammonium ions can fluctuate within wide limits and tend to increase over the course of the service life of the phosphating baths due to the dulling of the free acid. The weight ratio of alkali metal and / or ammonium ions to zinc ions, for example, can therefore be very low in freshly prepared phosphating baths, for example <0.5 and in extreme cases even 0, while it usually increases over time due to bath maintenance measures, so that the ratio <1 and can take values up to 10 and larger. Low zinc phosphate animal baths generally require additions of alkali metal or ammonium ions in order to be able to adjust the free acid to the desired value range at the desired weight ratio PO₄ ^3- : Zn <8. Analogous considerations can also be made about the proportions of alkali metal and / or ammonium ions to other bath components, for example phosphate ions.

In the case of lithium-containing phosphating baths, use is preferably avoided Formation of sodium compounds to adjust the free acid, because too high Sodium concentrations the beneficial effect of lithium on corrosion protection is suppressed. In this case, one uses to set the free Acid, preferably basic lithium compounds. Potassium is also an alternative suitable connections.

In principle, it does not matter in what form the layer-forming or layer-forming Influencing cations are introduced into the phosphating baths. Are nitrates however, to avoid avoiding the preferred upper limit of nitrate levels exceed. The metal ions are preferably used in the form of such compounds genes that do not introduce any foreign ions into the phosphating solution. Therefore it is on  cheapest to use the metals in the form of their oxides or their carbonates. Lithium can also be used as a sulfate.

Phosphating baths according to the invention are suitable for phosphating surfaces steel, galvanized or alloy galvanized steel, aluminum, aluminum steel or alloy-aluminized steel as well as aluminum-magnesium alloys. The term "aluminum" includes the technically usual aluminum alloy such as AlMg0.5Si1.4. The materials mentioned can - as is becoming increasingly common in automotive engineering - also side by side lie.

Parts of the body can also be made of the best pre-treated material hen, as is the case, for example, with the Bonazink® process. Here will the base material is first chromated or phosphated and then with coated with an organic resin. The phosphating process according to the invention then leads to phosphating at damaged areas of this pretreatment layer or on untreated backs.

The process is for use in immersion, spray or spray / immersion suitable method. It can be used particularly in automotive engineering where Treatment times between 1 and 8 minutes, especially 2 to 5 minutes, are common are. The use in band phosphating in the steel mill, whereby the Be action times are between 3 and 12 seconds, but is also possible. When using in tape phosphating processes it is recommended to use the bath concentrations in each case in the upper half of the Be preferred according to the invention rich to hire. For example, the zinc content can range from 1.5 to 2.5 g / l and the free acid content is in the range of 1.5 to 2.5 points. As Substrate for strip phosphating is particularly suitable for galvanized steel, especially special electrolytically galvanized steel.  

As is also common with other phosphating baths of the prior art the suitable bath temperatures, regardless of the area of application, between 30 and 70 ° C, with the temperature range between 45 and 60 ° C being preferred.

The phosphating process according to the invention is particularly suitable for the treatment of mentioned metal surfaces before painting, for example before a katho electrical dip coating, as is common in automotive engineering. It is also suitable as a pretreatment before a powder coating, as in is used for example for household appliances. The phosphating process is as To see part of the technically usual pretreatment chain. In this chain are the steps of cleaning / degreasing, intermediate rinse and activation upstream, the activation usually with Ti Activated agents containing tanphosphate.  

Embodiments

The phosphating processes and comparative processes according to the invention were carried out Steel sheets ST 1405, as used in automotive construction, checked. The following procedure, which is common in body production, was used as Dipping procedure carried out:

• 1.Clean with an alkaline cleaner (Ridolin® 1501, Henkel KGaA), An rate 2% in city water, 55 ° C, 4 minutes.
• 2. Rinse with city water, room temperature, 1 minute.
• 3. Activation with an activating agent containing titanium phosphate (Fixodine® 950, Henkel KGaA), approach 0.1% in deionized water, room temperature, 1 Minute.
• 4. Phosphating with phosphating baths with the following composition:
  1.0 g / l Zn ²⁺
  1.0 g / l Mn ²⁺
  0.1 g / l Fe ²⁺
  14 g / l PO₄ ^3-
  0.95 g / l SiF₆ ^2-
  0.2 g / l F⁻
  1.7 g / l (NH₃OH) ₂SO₄
  Polymer according to the table.
  In addition to the cations mentioned, the nitrate-free phosphating baths contained sodium ions to adjust the free acid if necessary.
  The free acid score was 0.9 and the total acid was 23; the pH 3.35. The free acid score is the consumption in ml of 0.1-normal sodium hydroxide solution to titrate 10 ml bath solution up to a pH of 3.6. Similarly, the total acid score indicates consumption in ml up to a pH of 8.2.
• 5. Rinse with deionized water.
• 6. Blow dry with compressed air.

The mass per unit area ("layer weight") was by detachment in 5% Chromic acid solution determined according to DIN 50 942. It is given in the table.

The phosphated test sheets were coated with a cathodic dip from the company BASF (FT 85-7042) coated. The corrosion protection effect was in one Alternating climate test according to VDA 621-415 tested over 9 laps. As a result, the Paint infiltration at the Ritz (half the width of the Ritz) included in the table.

table

Phosphating baths and phosphating results

Claims (20)

1. A method for phosphating metal surfaces made of steel, galvanized or galvanized steel, aluminum and / or aluminum-magnesium alloys, in which the metal surfaces by spraying or dipping for a time between 3 seconds and 8 minutes with a zinc-containing phosphating solution Touches, characterized in that the phosphating solution
0.2 to 3 g / l zinc ions
3 to 50 g / l phosphate ions, calculated as PO₄,
0.001 to 4 g / l manganese ions,
0.001 to 0.5 g / l of one or more polymers selected from polyethers, poly carboxylates, polymeric phosphonic acids, polymeric phosphinocarboxylic acids and nitrogen-containing organic polymers
and
one or more accelerators selected
0.3 to 4 g / l chlorate ions,
0.01 to 0.2 g / l nitrite ions,
0.05 to 2 g / l m-nitrobenzenesulfonate ions,
0.05 to 2 g / l m-nitrobenzoate ions,
0.05 to 2 g / l p-nitrophenol,
0.005 to 0.15 g / l hydrogen peroxide in free or bound form,
0.1 to 10 g / l hydroxylamine in free or bound form,
0.1 to 10 g / l of a reducing sugar
contains. 2. The method according to claim 1, characterized in that the phosphating solution solution additionally 1 to 50 mg / l nickel ions and / or 5 to 100 mg / l cobalt ions  contains. 3. The method according to one or both of claims 1 and 2, characterized records that the phosphating solution ent an additional 0.2 to 1.5 g / l of lithium ions holds. 4. The method according to one or more of claims 1 to 3, characterized records that the phosphating solution additionally fluoride in amounts of up to 2.5 g / l total fluoride, of which up to 1 g / l free fluoride, each calculated as F⁻, contains. 5. The method according to one or more of claims 1 to 4, characterized records that the phosphating solution as an accelerator 5 to 150 mg / l water contains peroxide in free or bound form. 6. The method according to one or more of claims 1 to 4, characterized records that the phosphating solution as an accelerator 0.1 to 10 g / l hydroxyl contains amine in free or bound form. 7. The method according to one or more of claims 1 to 6, characterized records that the phosphating solution contains no more than 0.5 g / l nitrate. 8. The method according to one or more of claims 1 to 7, characterized records that the phosphating solution the organic polymers in a conc contains between 0.01 and 0.1 g / l. 9. The method according to one or more of claims 1 to 8, characterized records that the organic polymers polyalkylene glycols with a molecular weight  represent in the range of 500 to 10,000. 10. The method according to one or more of claims 1 to 8, characterized in that the organic polymers are selected from homo or copolymer compounds containing amino groups, the structural units of the general formula (I) and also contain or consist of their hydrolysis products, where R¹ and R² are identical or different from one another and can represent hydrogen or alkyl having 1 to 6 carbon atoms. 11. The method according to one or more of claims 1 to 8, characterized in that the organic polymers are selected from poly-4-vinyl phenol compounds of the general formula (II), in which
n is a number between 5 and 100,
x are independently hydrogen and / or CRR₁OH groups, in which R and R₁ are hydrogen; are aliphatic and / or aromatic radicals having 1 to 12 carbon atoms. 12. The method according to one or more of claims 1 to 8, characterized in that the organic polymers are selected from amino group-containing homo- or copolymer compounds, comprising at least one polymer selected from the group consisting of a), b), c) or d), in which:

• a) a polymer material comprising at least one unit of the formula: in which:
  R₁ to R₃ are independently selected for each of the units 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;
  Y₁ to Y₄ are independently selected for each of the units from the group consisting of hydrogen, -CR₁₁R₅OR₆, -CH₂Cl or an alkyl or aryl group having 1 to 18 carbon atoms or Z: is, but at least a fraction of Y₁, Y₂, Y₃ or Y₄ of the homo- or copolymer compound or material Z must be: R R to R₁₂ are selected independently for each of the units from the group consisting of hydrogen, an alkyl , Ary, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group;
  R₁₂ can also be -O ^(-19) or -OH;
  W₁ is independently selected for each of the units from the group consisting of hydrogen, an acyl, an acetyl, 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; Tetraaryl ammonium; Tetraalkylammonium; Tetraalkylphosphonium; Tetraarylphosphonium or a condensation product of ethylene oxide, propylene oxide or a mixture or a copolymer thereof;
• b) includes:
  a polymer material with at least one unit of the formula: wherein:
  R₁ to R₂ are independently selected for each of the units 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;
  Y₁ to Y₃ are independently selected for each of the units from the group consisting of hydrogen, -CR₄R₅OR₆-, -CH₂Cl or an alkyl or aryl group with 1 to 18 carbon atoms or Z: is, however, at least one fraction of the Y₁, Y₂ or Y₃ of the final compound must be Z; R₄ to R₁₂ are independently selected for each of the units from the group consisting of hydrogen, an alkyl, aryl, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group; R₁₂ can also be -O ^(-1) or -OH;
  W₂ is independently selected for each of the units from the group consisting of hydrogen, an acyl, an acetyl, a benzoyl group; 3-allyloxy-2-hydroxy propyl; 3-benzyloxy-2-hydroxy-propyl-; 3-alkylbenzyloxy-2-hydroxy propyl-; 3-phenoxy-2-hydroxypropyl; 3-alkylphenoxy-2-hydroxy propyl; 3-butoxy-2-hydroxypropyl; 3-alkyloxy-2-hydroxypropyl; 2-hydroxy octyl; 2-hydroxylalkyl; 2-hydroxy-2-phenylethyl-; 2-hydroxy-2-alkyl phenylethyl-; 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) includes:
  a copolymer material wherein at least a portion of the copolymer has the structure and at least one fraction of said part is polymerized with one or more monomers which are independently selected 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, 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-diallymelamine, N, N-di-n-butyl acrylamide, di-n-butyl itaconate, di-n -Butyl maleate, diethylaminoethyl methacrylate, diethylene glycol monovinyl ether, diethyl fumarate, diethyl itaconate, diethyl vinyl phosphate, vinyl phosphonic acid, diisobutyl maleate, diisoproyl itaconate, diisopropyl maleate, dimethyl fumarate, dimethyl itaconate, dimethylma leat, di-n-nonyl fumarate, di n-nonyl maleate, dioctyl fumarate, di-n-octyl itaconate, di-n-propyl itaconate, N-dodecyl vinyl ether, acid ethyl fumarate, acid ethyl maleate, ethyl acrylate, ethyl cinnamate, N-ethyl ether methacrylamide, ethyl ethyl methacrylamide, ethyl 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, isoproyl methacrylate, isoproyl methacrylate Lauryl methacrylate, methacrylamide, methacrylic acid, methacrylonitrile, N-methylolacrylamide, N-methylol methacrylamide, N-isobutoxymethylacrylamide, N-isobutoxymethyl methacrylamide, N-alkyloxymethylacrylamide, N-alkyl oxymethyl methacrylamide, N-vinylcaprolactam, methyl methacrylamide, N-methyl methacrylamide, N-methyl methacrylate, N-methyl acrylate m-methyl styrene, o-methyl styrene, p-methyl styrene, 2-methyl-5-vinyl pyridine, n-propyl methacrylate, sodium p-styrene sulfonate, stearyl methacrylate, styrene, p-styrene sulfone acid, p-styrene sulfonamide, vinyl bromide, 9-vinyl carbazole, vinyl chloride, vinylidene chloride, 1-vinyl naphthalene, 2-vinyl naphthalene, 2-vinyl pyridine, 4-vinyl pyridine, 2-vinyl pyridine-N-oxide, 4-vinyl pyrimidine, N-vinyl pyrrolidone ; and W₁, Y₁-Y₄ and R₁-R₃ are as described under a);
• d) comprises a condensation polymer composed of the polymeric materials a), b) or c), a condensable form of a), b), c) or a mixture thereof being 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, the condensation resin product being added to at least part of the same by adding "Z", by reacting the resin product then reacted further with 1) an aldehyde or ketone 2) a secondary amine to form a final adduct which can react with an acid.

13. The method according to claim 12, characterized in that at least one Fraction of groups Z of the organic polymer a polyhydroxyalkylamine Has functionality that results from the condensation of an amine or of Am moniac with a ketosis or aldose that contains 3 to 8 carbon atoms having. 14. The method according to claim 12, characterized in that the organic Po lymer a condensation product of a polyvinylphenol with a molecular weight in the range of 1000 to 10,000 with formaldehyde or paraformaldehyde and with a secondary organic amine. 15. The method according to claim 14, characterized in that the secondary or ganic amine is selected from methylethanolamine and N-methylglucamine. 16. The method according to one or more of claims 1 to 8, characterized in that the organic polymers are selected from substituted polyalkylene derivatives where R¹, R², R³ can independently be hydrogen or a methyl or ethyl group,
x = 1, 2, 3 or 4 means and
Y represents a substituent which contains at least one nitrogen atom which is incorporated in an alkylamine group or in a mono- or polynuclear saturated or unsaturated heterocycle. 17. The method according to claim 16, characterized in that R¹, R², R³ each Mean hydrogen and that x = 1. 18. The method according to claim 16 or 17, characterized in that the organic polymers rule one or more of the following units: 19. The method according to one or more of claims 1 to 8, characterized records that the organic polymers amino-containing polymeric sugars represent derivatives.   20. The method according to claim 19, characterized in that the polymeric sugar derivatives contain the following structural groups: