DE10358310A1 - Two-stage conversion treatment - Google Patents

Abstract

A method for the two-stage corrosion protection treatment of metal surfaces, wherein said DOLLAR A a) in a first step with a chromium-free first aqueous solution having a pH in the range of 1.5 to 5 brings in the total of at least 0.01 g / l and up to 10 g / l of Ti and / or Zr and / or Si ions and at least one such amount of fluoride that the atomic ratio of Ti to F and / or Zr to F and / or Si to F in the range of 1: 1 to 1: 6, and then DOLLAR A b) in a second step with a chromium-free second aqueous solution having a pH in the range of 1.5 to 5 brings into contact, the total of at least 0.01 g / l and up to 10 g / l Ti and / or Zr and / or Si ions and at least one such amount of fluoride contains that the atomic ratio of Ti to F and / or Zr to F and / or Si to F in the range from 1: 1 to 1: 6, and in addition such an amount of soluble anions of oxo acids of molybdenum and / or tungsten in the oxidation state VI contains that the total concentration of molybdenum and / or tungsten, calculated as MoO¶¶¶¶. 2 · and / or WO¶¶¶¶2 ·, in the range of 5 to 1500 mg / l.

Description

The Invention is in the field of corrosion protection treatment of Metal surfaces, For example, of vehicle bodies or household appliances. there becomes on iron-containing surfaces such as steel surfaces and / or on selected Non-ferrous surfaces such as zinc or zinc alloys (e.g., galvanized or zinc) alloy-galvanized steel), aluminum, magnesium or their alloys a corrosion-protective Layer generated. This improves corrosion protection and adhesion of an applied over it Layer based on organic polymers, such as a Paint or an adhesive. Here is a special feature of Invention in that no toxic chromium must be used.

 Out Metal sheets joined together Components such as vehicle bodies, housing of household appliances or metallic pieces of furniture can be made out Metal sheets are assembled, which is not a permanent corrosion-protective coating exhibit. In a multi-stage process sequence can a permanent corrosion protection Coating consisting of a conversion layer and a coating layer be generated after assembly of the metallic components. One well-known example of this is the process sequence phosphating and painting, as for example usual in the automotive industry is. The term "conversion treatment" states that components the treatment solution with the metal surface react chemically, creating a corrosion protection layer, into both the components of the treatment solution and metal atoms the metal surface are installed.

vehicle bodies such as automobile bodies are currently made of steel and / or other metallic materials such as galvanized Steel or aluminum joined together. After joining The bodies are cleaned and ge before painting a conversion treatment for Achieve adequate corrosion protection and sufficient paint adhesion subjected. After that the bodies are painted, nowadays in usually by a cathodic electrodeposition coating. A similar one Procedure can Household appliances containing metallic components such as refrigerators, freezers, Washing machines, spin dryers, Stoves, microwave ovens or even metallic furniture be subjected. Due to the lower requirements of the Corrosion protection for such objects these are usually treated with one after conversion treatment Powder paint painted.

When Conversion treatment is widespread in home appliances phosphating common. For vehicle bodies, the conversion treatment takes place exclusively as so-called "layer-forming" zinc phosphating. Therefor are the vehicle bodies with an aqueous solution having a pH of about 2.5 to about 3.8 in contact brought about 0.3 to 2 g / l zinc ions and about 10 to about 20 g / l phosphate ions. Often contain these phosphating solutions additionally about 0.3 to 2 g / l manganese ions and often nickel or copper ions. This treatment produces a layer of crystalline on steel surfaces Zinc iron phosphates, on zinc or aluminum surfaces Layer of crystalline zinc phosphates.

In order to These crystalline zinc-containing Phophatschichten sufficient Effect for Anticorrosive and paint adhesion unfold, becomes the real Phosphating step of additional Accompanied steps. For example, the metal surfaces are present the phosphating first - in the Usually multi-level - cleaned and subsequently activated. For The activation step is carried along with the metal surfaces a solution in contact, mainly secondary Alkali metal phosphates and suspended colloidal titanium phosphates contains. This step must be very carefully be controlled to a sufficient quality of the subsequent phosphating to ensure. In particular, the activating baths consume comparatively in comparison with phosphating baths quickly, allowing them in short intervals of a few days to a few weeks have to be renewed. The supervision and care of the activating baths therefore represents a significant proportion of the care and monitoring effort for one Phosphating line.

On the actual phosphating step is followed by a regular one so-called post-passivation. By this Nachpassivierung become remaining pores in the crystalline phosphate layer closed and Corrosion protection and paint adhesion improved. For this will be the phosphated metal surfaces with an aqueous solution in touch brought, which can contain different components. In practical Use is currently Nachpassivierungslösungen based on hexavalent Chromium, from complex fluorides of titanium and / or zirconium, of reactive Polymers of vinyl phenol derivatives or copper ions. Also these post-passivation baths have to regularly checked and adjusted become.

A Conversion treatment in the form of phosphating thus requires in addition to cleaning usually at least 3 treatment baths for activation, Phosphating and post-passivation, all controlled regularly and must be readjusted or renewed if necessary. These at least 3 required baths and the additional between them lying rinses lead to a high space requirement and capital expenditure and thus increase the costs for the manufacture of vehicle bodies and household appliances. In addition, arise during phosphating heavy metal-containing waste, disposed of costly Need to become.

• a) 0,01 bis 5 Gewichtsteile gelöster Phosphationen,
• b) 0,1 bis 2 Gewichtsteile Titanionen,
• c) 0,05 bis 5 Gewichtsteile Fluoridionen und
• d) 0,01 bis 2 Gewichtsteile eines wasserlöslichen Beschleunigers, der zum Beispiel eine Kombination aus Salpetersäure und Ammoniumheptamolybdat darstellen kann.

Apart from phosphating, other methods for producing a so-called conversion layer are known, which protect the underlying metal from corrosion and which constitutes a primer for a subsequent coating layer. For example, this can be achieved with conversion solutions based on complex fluorides of boron, silicon, titanium or zirconium. Most of these complex fluorides are used together with organic polymers. Examples of such conversion treatments are mentioned in DE-A-101 31 723 and the literature cited therein. However, none of these alternative methods has been able to displace the phosphating pretreatment before painting in the automotive industry. This also applies to the teachings of the following three documents:
Out US Pat. No. 6,193,815 is a treatment solution for generating a conversion layer

• a) 0.01 to 5 parts by weight of dissolved phosphate ions,
• b) 0.1 to 2 parts by weight of titanium ions,
• c) 0.05 to 5 parts by weight of fluoride ions and
• d) 0.01 to 2 parts by weight of a water-soluble accelerator, which may be, for example, a combination of nitric acid and ammonium heptamolybdate.

there it is obvious that the titanium ions and the fluoride ions are related to each other react to fluoro complexes or used directly as fluorocomplexes can be. According to embodiments can be used as an accelerator in addition to heptamolybdate and tungstate become. This treatment solution is special for the treatment of aluminum surfaces suitable.

WHERE 03/078682 discloses a method of generating a conversion layer on a metallic surface by treating with an aqueous solution with the following components: a) a source of tungsten ions and b) a soluble Material containing zircon. After that, the surface becomes dried and / or baked. As zirconium compounds are, for example hexafluorozirconic and their salts suitable.

• a) eine anionische Komponente, die beispielsweise ein Fluorokomplex von Titan oder Zirkon sein kann,
• b) eine kationische Komponente ausgewählt aus den Metallen Co, Mg, Mn, Zn, Ni, Sn, Cu, Zr, Fe und Sr,
• c) eine ausreichende Menge Säure, um einen pH-Wert im Bereich von 0,5 bis 5 einzustellen,
• d) Oxo-Anionen von Phosphor oder Phosphonatanionen,
• e) ein organisches Polymer.

US 5,449,415 describes a "no-rinse" conversion process for in particular cold-rolled steel. "no-rinse" means that the treatment solution is not rinsed off after the application but is dried directly. As essential components, this treatment solution contains:

• a) an anionic component, which may be, for example, a fluorocomplex of titanium or zirconium,
• b) a cationic component selected from the metals Co, Mg, Mn, Zn, Ni, Sn, Cu, Zr, Fe and Sr,
• c) a sufficient amount of acid to adjust a pH in the range of 0.5 to 5,
• d) oxo anions of phosphorus or phosphonate anions,
• e) an organic polymer.

Preferably contains this solution additionally another component selected from tungstate, molybdate, silicotungstate and silicomolybdate.

The aforementioned examples of conversion solutions containing complex fluorides of titanium or zirconium, provide conversion solutions to Creating conversion layers on bare metal surfaces. However, it is also known solutions complex fluorides of titanium or zirconium for passivating aftertreatment of phosphate layers.

The present invention has as its object, the process chain z. B. to make the automobile production more economical and ecological. The intention is to avoid the formation of waste containing heavy metals, especially waste containing toxic heavy metals such as chromium or nickel. On the other hand, the process sequence should be shortened compared to the conventional phosphating. This, on the one hand, shortens the length of the production line and, on the other hand, reduces the number of rinsing steps required, which leads to a saving of water. Nevertheless, a conversion layer is to be produced, the ent quality in terms of corrosion protection and paint adhesion of a conventional phosphating speaks.

• a) in einem ersten Schritt mit einer chromfreien ersten wässrigen Lösung mit einem pH-Wert im Bereich von 1,5 bis 5 in Kontakt bringt, die insgesamt mindestens 0,01 g/l, vorzugsweise mindestens 0,025 g/l, und bis zu 10 g/l, vorzugsweise bis zu 1 g/l, insbesondere bis zu 0,5 g/l Ti- und/oder Zr- und/oder Si-Ionen sowie mindestens eine solche Menge an Fluorid enthält, dass das Atomverhältnis Ti zu F und/oder Zr zu F und/oder Si zu F im Bereich von 1 : 1 bis 1 : 6 liegt, und danach, mit oder ohne Zwischenspülung mit Wasser,
• b) in einem zweiten Schritt mit einer chromfreien zweiten wässrigen Lösung mit einem pH-Wert im Bereich von 1,5 bis 5 in Kontakt bringt, die insgesamt mindestens 0,01 g/l, vorzugsweise mindestens 0,025 g/l, und bis zu 10 g/l, vorzugsweise bis zu 1 g/l, insbesondere bis zu 0,5 g/l Ti- und/oder Zr- und/oder Si-Ionen sowie mindestens eine solche Menge an Fluorid enthält, dass das Atomverhältnis Ti zu F und/oder Zr zu F und/oder Si zu F im Bereich von 1 : 1 bis 1 : 6 liegt, und die zusätzlich eine solche Menge löslicher Anionen von Oxosäuren von Molybdän und/oder Wolfram in der Oxidationsstufe VI enthält, dass die Gesamtkonzentration von Molybdän und/oder Wolfram, berechnet als MoO₄ ^2– und/oder WO₄ ^2–, im Bereich von 5 bis 1500 mg/l liegt.

The present invention is a process for the two-stage corrosion protection treatment of metal surfaces, wherein the metal surfaces

• a) contacting in a first step with a chromium-free first aqueous solution having a pH in the range of 1.5 to 5, the total of at least 0.01 g / l, preferably at least 0.025 g / l, and up to 10 g / l, preferably up to 1 g / l, in particular up to 0.5 g / l Ti and / or Zr and / or Si ions and at least one such amount of fluoride contains that the atomic ratio of Ti to F and / or Zr to F and / or Si to F in the range of 1: 1 to 1: 6, and thereafter, with or without intermediate rinsing with water,
• b) contacting in a second step with a chromium-free second aqueous solution having a pH in the range of 1.5 to 5, the total of at least 0.01 g / l, preferably at least 0.025 g / l, and up to 10 g / l, preferably up to 1 g / l, in particular up to 0.5 g / l Ti and / or Zr and / or Si ions and at least one such amount of fluoride contains that the atomic ratio of Ti to F and or Zr to F and / or Si to F in the range from 1: 1 to 1: 6, and which additionally contains such an amount of soluble anions of oxo acids of molybdenum and / or tungsten in the oxidation state VI, that the total concentration of molybdenum and / or tungsten, calculated as MoO ₄ ^2- and / or WO ₄ ^2- , in the range of 5 to 1500 mg / l.

Of course it is This two-stage process is part of the longer treatment chain the production of painted metal objects such as automobile bodies, household appliances and the like. In this treatment chain become the assembled components first cleaned and rinsed before they are the two-stage according to the invention Be subjected to conversion treatment. Between the two steps a) and b) of the two-stage process according to the invention can be rinsed with water but not necessarily. After the second step b) is in the Usually rinsed one to several times with water, the last rinse step preferably with demineralized water. After that, the Object to be painted. For low demands on the corrosion protection As with household appliances, this can be done with a powder coating respectively. To master the higher one Corrosion protection requirements of the automotive industry is preferably brought the currently technically usual multi-layer paint system, the metal next layer usually represents a cathodic electrodeposition paint. The process sequence according to the invention is not only able to prepare the metal surfaces for painting, but it can also serve as a foundation for bonding.

there the sub-steps a) and b) are the only steps (apart from the usual Rinsing steps), the between cleaning the parts and applying a coat based on organic polymers such as a varnish or an adhesive for the conversion treatment of the metal surfaces have to. An additional Activation such as phosphating or another Post-pass step is not required.

The two-stage process sequence according to the invention can also be used for the passivation of bare metal sites which arise when the components such as, for example, the automobile bodies are completely assembled from already precoated material. The following considerations apply here:
In principle, it would be economically and ecologically advantageous to produce metallic components already pre-coated by the manufacturer of the metal strips material and after assembly only to clean and paint. Waste associated with the pretreatment would then be centralized by the manufacturers of the metal strips and not widely dispersed by the downstream converters of the metal strips. Accordingly, pre-coated metal strips are already offered on the market. On the one hand, these can be pre-phosphated, ie they can carry a phosphate layer but no further coating based on organic polymers. In the automotive and household appliance industry, metal strips are increasingly being processed which are already provided with a corrosion protection layer by the manufacturer of the strips. Such materials are known for example under the name Granocoat ^®, DuraSteel ^{®, ®} and Bonazinc Durazinc ^®. They carry a thin organic coating over a conversion layer, for example a chromating or phosphating layer. The organic coating consists of polymer systems such as epoxy or polyurethane resins, polyamides and polyacrylates. Solid additives such as silicic acids, zinc dust and soot improve the corrosion protection and, due to their electrical conductivity, allow the metal parts coated with layers of about 0.3 to about 10 μm, preferably up to about 5 μm, to be electrically welded and electrolytically painted. The coating of the substrate materials is generally carried out in a two-stage process, in which first the inorganic conversion layer is produced and subsequently the organic polymer film is applied in a second treatment stage. Further information can be found in DE-A-100 22 075 and in the literature cited therein.

in the Tape method with a coating based on organic polymers provided metal sheets are therefore already partially in the construction of Vehicle bodies, used by household appliances and furnishings. In the automotive industry, the strictest requirements in terms of Corrosion protection and adhesion of a subsequently applied paint, because vehicles are the strongest Are exposed to corrosion stresses. Currently none are Vehicle bodies made exclusively organically pre-coated metal sheets produced. Rather, it will this material possibly together with non-pre-coated sheets installed to the vehicle bodies. The assembled bodies therefore currently undergo the usual pretreatment process before painting, d. H. they become the elaborate process sequence subjected to phosphating.

in principle could replaced the phosphating by a less expensive pretreatment process be when the vehicle bodies exclusively from organically pre-coated Metal substrate would be produced. However, this must be the problem solved be that when assembling bodies from organically pre-coated Metal sheets inevitably There are places where the organic precoating is damaged or completely missing. This is for example at cut edges, at welding points and at polished places the case.

Out establish The better corrosion protection effect are often used in vehicle construction organically pre-coated metal substrates used in which as a metal substrate electrolytically galvanized or hot dip galvanized Steel serves. In such organically coated metal substrates But these are the places with a damaged organic layer especially difficult to deal with as they are in terms of their electrochemical potentials and their chemical reactivity from the usual Distinguish metal surfaces. At such damaged Places are usually both shares of the steel substrate (ie iron) as well as the zinc coating bare.

there can have a high local area ratio of Steel (iron) to zinc, for example, a ratio of> 9: 1. In particular this is the case with cut edges that cross a section through represent the coated steel substrate. The corrosion conditions soften at those border areas that combine zinc and iron, from the other conditions on the homogeneous surface from. Depending on the local ratio from zinc to iron at the exposed metal sites a different electrochemical potential between the potentials of zinc and iron. Furthermore arise during processing the bodies ground areas, the special conditions and thus have special electrochemical potentials. Because The grinding process creates an activated interface of Steel (iron) with finely divided reactive zinc.

The two-stage according to the invention Treatment sequence is for suitable, at said problem areas, where the organic Pre-coating damaged is or is missing, a sufficient Passivierungsschicht for another To produce paint.

• I) Bleche aus Metall, die eine Beschichtung auf Basis organischer Polymere tragen, schneidet und/oder stanzt und/oder umformt und die hierdurch erhaltenen Metallteile zur Herstellung des Bauteils zusammenfügt, wobei Bereiche der Metalloberfläche des Blechs entstehen, die nicht von der Beschichtung auf Basis organischer Polymere bedeckt sind;
• II) das zusammengefügte Bauteil reinigt,
• III) das gereinigte zusammengefügte Bauteil einer Verfahrensfolge unterzieht, die auf den im Teilschritt I) entstandenen Bereichen der Metalloberfläche, die nicht von der Beschichtung auf Basis organischer Polymere bedeckt sind, eine Passivierungsschicht erzeugt, die keine Zinkphosphatschicht darstellt, wobei man die Bereiche der Metalloberfläche des Blechs, die nicht von der Beschichtung auf Basis organischer Polymere bedeckt sind a) in einem ersten Schritt mit einer chromfreien ersten wässrigen Lösung mit einem pH-Wert im Bereich von 1,5 bis 5 in Kontakt bringt, die insgesamt mindestens 0,01 g/l, vorzugsweise mindestens 0,025 g/l, und bis zu 10 g/l, vorzugsweise bis zu 1 g/l, insbesondere bis zu 0,5 g/l Ti- und/oder Zr- und/oder Si-Ionen sowie mindestens eine solche Menge an Fluorid enthält, dass das Atomverhältnis Ti zu F und/oder Zr zu F und/oder Si zu F im Bereich von 1 : 1 bis 1 : 6 liegt, und danach, mit oder ohne Zwischenspülung mit Wasser, b) in einem zweiten Schritt mit einer chromfreien zweiten wässrigen Lösung mit einem pH-Wert im Bereich von 1,5 bis 5 in Kontakt bringt, die insgesamt mindestens 0,01 g/l, vorzugsweise mindestens 0,025 g/l, und bis zu 10 g/l, vorzugsweise bis zu 1 g/l, insbesondere bis zu 0,5 g/l Ti- und/oder Zr- und/oder Si-Ionen sowie mindestens eine solche Menge an Fluorid enthält, dass das Atomverhältnis Ti zu F und/oder Zr zu F und/oder Si zu F im Bereich von 1 : 1 bis 1 : 6 liegt, und die zusätzlich eine solche Menge löslicher Anionen von Oxosäuren von Molybdän und/oder Wolfram in der Oxidationsstufe VI enthält, dass die Gesamtkonzentration von Molybdän und/oder Wolfram, berechnet als MoO₄ ^2– und/oder WO₄ ^2–, im Bereich von 5 bis 1500 mg/l liegt
• IV) erwünschtenfalls, aber nicht zwingend das im Teilschritt c) behandelte Bauteil ein- oder mehrmals mit Wasser spült und
• V) mit einer Lackschicht beschichtet.

Therefore, there is a specific aspect of the present invention in a method for producing a painted metal parts-containing component, wherein

• I) Sheets of metal carrying, cutting and / or punching and / or reshaping a coating based on organic polymers and assembling the resulting metal parts to make the component, thereby creating areas of the metal surface of the sheet which are not based on the coating organic polymers are covered;
• II) cleans the assembled component,
• III) subjecting the cleaned assembled component to a process sequence which, on the areas of the metal surface which are not covered by the organic polymer based coating, produces a passivation layer which does not constitute a zinc phosphate layer, the areas of the metal surface of the Sheets not covered by the organic polymer-based coating a) in a first step, bringing into contact with a chromium-free first aqueous solution having a pH in the range of 1.5 to 5, containing a total of at least 0.01 g / l, preferably at least 0.025 g / l, and up to 10 g / l, preferably up to 1 g / l, in particular up to 0.5 g / l of Ti and / or Zr and / or Si ions and at least one contains such an amount of fluoride that the atomic ratio Ti to F and / or Zr to F and / or Si to F in the range of 1: 1 to 1: 6, and thereafter, with or without intermediate rinsing with water, b) in one second step m it brings into contact with a chromium-free second aqueous solution having a pH in the range from 1.5 to 5, which in total at least 0.01 g / l, preferably at least 0.025 g / l, and up to 10 g / l, preferably to to 1 g / l, in particular up to 0.5 g / l Ti and / or Zr and / or Si ions and at least one such amount of fluoride contains that the atomic ratio of Ti to F and / or Zr to F and / or Si to F is in the range from 1: 1 to 1: 6, and which additionally contains such an amount of soluble anions of oxo acids of molybdenum and / or tungsten in the oxidation state VI that the total concentration of molybdenum and / or tungsten, calculated as MoO ₄ ^2- and / or WO ₄ ^2- , in the range of 5 to 1500 mg / l
• IV) if desired, but not necessarily the component treated in step c) one or more times with water rinses and
• V) coated with a lacquer layer.

The further explanations apply both to the general aspect of the present invention according to claim 1 and to its specific application according to claim 2:
In contrast to the second aqueous solution which is used in substep b), the first aqueous solution in substep a) preferably contains no compounds of molybdenum or tungsten. Their use brings no technical advantage and would therefore be uneconomical. However, he would not be technically disadvantageous.

Both in substep a) and in substep b), an aqueous treatment solution is used which has a total of at least 0.01 g / l, preferably at least 0.025 g / l, and up to 10 g / l, preferably up to 1 g / l, contains in particular up to 0.5 g / l Ti and / or Zr and / or Si ions and at least one such amount of fluoride that the atomic ratio of Ti to F and / or Zr to F and / or Si to F in the range from 1: 1 to 1: 6, and which may, but not, contain at least 0.005 g / L, preferably at least 0.01 g / L, and up to 20 g / L, preferably up to 1 g / L of organic polymers got to. The said Ti, Zr and / or Si ions can be used completely in the form of hexafluoro complexes such as, for example, the hexafluoroacids or their salts which are soluble in water in the stated concentration range, for example the sodium salts. In this case, the atomic ratio is 1: 6. However, it is also possible to use complex compounds in which less than six fluoride ions in each case are connected to the central elements Ti, Zr or Si. These can form themselves in the treatment solution if hexafluoro complexes of at least one of the central elements Ti, Zr or Si and also at least one further compound of one of these central elements are added to it. As such further compounds are, for example, nitrates, carbonates, hydroxides and / or oxides thereof or another of the three mentioned central elements into consideration. For example, the treatment solution may contain hexafluorozirconations as well as (preferably colloidal) silica (SiO ₂ ) or their reaction products. Unreacted silica may be suspended in the treatment solution. Such a treatment solution can also be obtained by using hydrofluoric acid or its (optionally acidic) salts together with those compounds of Ti, Zr and / or Si which can form fluorocomplexes herewith. Examples are the already mentioned nitrates, carbonates, hydroxides and / or oxides. Preferably, a total of such an amount of Ti, Zr and / or Si as the central metal and such an amount of fluoride, that the atomic ratio of central metal to fluoride is less than or equal to 1 to 2, in particular less than or equal to 1 to 3. The atomic ratio may also become less than 1 to 6 when the treating solution contains more fluoride, for example in the form of hydrofluoric acid or its salts, than is stoichiometrically required to form the hexafluorocomplexes of the central metals Ti, Zr and / or Si. For example, the atomic ratio may become as small as 1 to 12 or 1:18, or even less, by employing a corresponding excess of fluoride, ie, two or three times or even more times what is necessary to complete formation of the hexafluoro complexes.

• a) Polyacrylsäure oder deren Homopolymere,
• b) Hexafluorozirkonsäure,
• c) 0,17 bis 0,3 g/l Fluorwasserstoffsäure und
• d) bis zu 0,6 g/l Hexafluorotitansäure,

gemäß EP-B-8 942 eine Behandlungslösung, enthaltend

• a) Polyacrylsäure oder eines Esters davon und
• b) mindestens einer der Verbindungen H₂ZrF₆, H₂TiF₆ und H₂SiF₆, wobei der pH-Wert der Lösung unterhalb von 3,5 liegt, (weitere Polymere, die in ähnlichen Behandlungsbädern eingesetzt werden können, sind in WO 02/20652 aufgeführt),

gemäß US-A-4 992 116 eine Behandlungslösung mit pH-Werten zwischen etwa 2,5 und 5, die mindestens drei Komponenten enthält:

• a) Phosphationen im Konzentrationsbereich zwischen 1,1 × 10^–5 bis 5,3 × 10^–3 mol/l, entsprechend 1 bis 500 mg/l,
• b) mindestens eine Fluorosäure eines Elements der Gruppe Zr, Ti, und Si und
• c) eine Polyphenolverbindung, erhältlich durch Umsetzung von Poly(vinylphenol) mit Aldehyden und organischen Aminen,

gemäß WO 92/07973 eine Behandlungslösung, die als wesentliche Komponenten in saurer wässriger Lösung H₂ZrF₆ und ein 3-(N-C_1-4alkyl-N-2-hydroxyethylaminomethyl)-4-hydroxystyrol-Polymer enthält.In this case, in partial step a) treatment solutions can be used which contain combinations of ingredients known in the prior art, for example according to US Pat. No. 5,129,967 a treatment solution which contains at least the following components in water:

• a) polyacrylic acid or its homopolymers,
• b) hexafluorozirconic acid,
• c) 0.17 to 0.3 g / l hydrofluoric acid and
• d) up to 0.6 g / l hexafluorotitanic acid,

according to EP-B-8 942 a treatment solution containing

• a) polyacrylic acid or an ester thereof and
• b) at least one of the compounds H ₂ ZrF ₆ , H ₂ TiF ₆ and H ₂ SiF ₆ , wherein the pH of the solution is below 3.5, (further polymers which can be used in similar treatment baths are in WO 02/20652 listed),

according to US Pat. No. 4,992,116, a treatment solution with pH values between about 2.5 and 5, which contains at least three components:

• a) phosphate ions in the concentration range between 1.1 × 10 ^-5 to 5.3 × 10 ^-3 mol / l, corresponding to 1 to 500 mg / l,
• b) at least one fluoro acid of an element of the group Zr, Ti, and Si and
• c) a polyphenol compound obtainable by reacting poly (vinylphenol) with aldehydes and organic amines,

according to WO 92/07973 a treatment solution containing as essential components in acidic aqueous solution H ₂ ZrF ₆ and a 3- (NC _1-4 alkyl-N-2-hydroxyethylaminomethyl) -4-hydroxystyrene polymer.

in the Sub-step a) are also those treatment solutions can be used in which the organic polymers selected are from homopolymers and copolymers of vinylpyrrolidone. Such treatment solutions are described in DE-A-100 05 113 and DE-A-101 31 723. Provided accordingly in the inventive method treatment solution used, which contains copolymers of vinylpyrrolidone, these can Copolymers except Vinylpyrrolidone one or more other monomers. she can for example, as copolymers of 2 components or as copolymers of 3 components (= terpolymers) are present. Furthermore, mixtures can of homo- and two-component copolymers, homopolymers and terpolymers or two-component copolymers and terpolymers.

When Homopolymers or copolymers of vinylpyrrolidone are, for example the listed in Table 1 polymers or polymers of the monomers listed there into consideration. Copolymers of vinylpyrrolidone with monomers containing caprolactam or imidazole groups are particularly preferred.

Table 1: Examples of homopolymers or copolymers of vinylpyrrolidone

Contains the treatment solution in the Sub-step a) organic polymers, they are preferably in concentrations of at least 0.005 g / l, in particular at least 0.01 g / l, and up to 20 g / l, in particular up to 1 g / l before.

In contrast, is the treatment solution for the Partial step b) preferably free of organic polymers. you Use in sub-step b) is possible without disadvantage brings but also no significant technical advantage and is therefore uneconomical.

in the Sub-step b) means the formulation "soluble anions of oxo acids of molybdenum and / or tungsten in the oxidation state VI ", that the compounds, as a rule Salts containing the said anions, among those in this Revelation describes conditions regarding concentrations, pH values and temperatures in the treatment solution are soluble. It is the expert aware that under the conditions mentioned in the treatment solution the Anions of oxo acids of molybdenum and / or tungsten in the oxidation state VI in quite another Can be in shape when they were introduced. Crucial for this are, on the one hand, the pH-dependent protolysis equilibria the respective anions. these can Partially as free anions, depending on the pH value but also in partial or completely protonated form. Furthermore it is known to the person skilled in the art that the said anions, depending on the temperature, pH and concentration for condensation or hydrolytic Splitting tend. Also for this the position of the corresponding equilibria is decisive. For example can the anions of oxo acids of molybdenum and / or tungsten in the oxidation state VI in the form of orthometallates, Metametalates, parametallates, polymetalates, in particular heptametallates or introduced as Heteropolymetallate. It will be here under "Metallates" the Molybdate or the tungstates understood. They are preferably used as salts with cations such as sodium, potassium, lithium, calcium, cerium, barium, Magnesium, strontium, ammonium or used as corresponding acids.

The Metal surfaces, with the method according to the invention can be treated are preferably selected from surfaces steel, galvanized or alloy-galvanized steel, aluminized steel, Zinc, aluminum, magnesium or alloys containing at least 50% Atomic percent of zinc, aluminum or magnesium. It also can different metal surfaces coexist, as is increasingly the case in automotive engineering is. Especially in the treatment of steel, the inventive method its advantages. Especially for these surfaces So far, there is no suitable method except phosphating to the high corrosion protection and paint adhesion requirements in vehicle construction to fulfill. The inventive method leads Application on steel surfaces however, properties relating to corrosion protection and paint adhesion, those of a technically advanced phosphating are comparable.

Either the first and second treatment solutions may contain metal ions, which has been removed from the surfaces to be treated are. These are in particular iron, zinc and / or aluminum ions. these can for example, in concentrations between 0.001 and 1 g / l, in particular between 0.005 and 0.5 g / l.

The second aqueous solution can additionally Complexing agents, for example, in amounts of 0.01 to 10 g / l, in particular from 0.05 to 5 g / l. For smaller quantities the technical advantage increasingly lost. Larger quantities bring no Another advantage and are therefore uneconomical. However, they also bother you Not. The complexing agents can for example, selected be from chelating anions of hydroxycarboxylic acids or of polybasic carboxylic acids such as lactate, oxalate, citrate, tartrate or gluconate. Acetylacetonate is also suitable as a complexing agent. Further suitable complexing agents are amino, imino or nitrilocarboxylic acids such as for example, ethylenediaminetetraacetic acid or nitrilotriacetic acid or their anions. Polybasic phosphonates, phosphonocarboxylates or Amino, imino or Nitriloalkylenphosphonate are also as Complexing agent suitable. Examples are 1-hydroxyethane-1,1-diphosphonic acid, nitrilotri (methylenephosphonic acid), phosphonobutane tricarboxylic acid and further, known in the art phosphonic acids with similar properties.

The first and / or the second treatment solution preferably has one pH of at least 1.5, in particular of at least 1.7, and up to 5, preferably up to 4. The pH values of the first and second treatment solution Of course be different. It is especially for the second aqueous solution preferred that these buffer substances for the said pH range contains.

As mentioned above, brings the presence of organic polymers in the second aqueous solution no significant technical advantage. Therefore it is economical establish preferred that these not more than 5 mg / l of organic polymers contains.

For carrying out partial step a) treatment parameters can be selected, as they are mentioned in the cited literature. This is especially true for the temperature of the first aqueous solution, the Contact time with the metal surface and the type of job. In the second step b), the metal surfaces are brought into contact with the aqueous solution, preferably for a period of time in the range of 5 seconds to 10 minutes, in particular 10 seconds to 1 minute. This can be done, as is technically known, by immersing the metal surfaces in the treatment solution, by spraying with the treatment solution or by combinations thereof. The temperature of the second aqueous solution is preferably at least 20 ° C., in particular at least 30 ° C., and preferably not more than 60 ° C., in particular not more than 50 ° C. At lower temperatures, the effect of the treatment decreases more and more.

Higher temperatures as the above limits do not hurt, but are not required and therefore due to the increased Energy demand economically disadvantageous.

Abbreviations:

s

seconds;

min

minutes;

H

hours

d

days

VE water

completely desalinated water;

CASS

copper Accelerated salt spray test

EC

electrolytically galvanized Stole,

CRS

cold rolled steel

KTL

cathodic electrodeposition paint

• Ridoline® ^® and Ridosol® are alkaline cleaners the applicant.
• Sokalan ^® HP 56 is a vinylimidazole-vinylpyrrolidone copolymer (Fa. BASF), CAS No. 117197-37-2.
• Molybdate was introduced as the ammonium salt.
• PH levels were decreased, if necessary, down with nitric acid top with ammonia solution or with sodium carbonate solution set.

Example 1: MoO ₄ / ZrF ₆ rinse after conversion treatment with H ₂ ZrF ₆ / Sokalan HP56

Substrate: Aluminum AA 6016 Process sequence (spray application):

Corrosion test: aluminum DIN 50021 CASS, 10 d; Infiltration at the Ritz

Comparative Example 1 Conversion Treatment with H ₂ ZrF ₆ / Sokalan HP56 without Rinsing

Substrate: Aluminum AA 6016 Process sequence (spray application):

Corrosion test: aluminum DIN 50021 CASS, 10 d; Infiltration at the Ritz

Table 1: Results of test series 1

Example 2: MoO ₄ / ZrF ₆ rinse after conversion treatment with H ₂ ZrF ₆ / Sokalan HP56

Substrate: EG process sequence (immersion application):

Comparative Example ₂ Conversion Treatment with H ₂ ZrF ₆ / Sokalan HP56 without Rinsing

Substrate: EG process sequence (immersion application):

Paint adhesion test: EG Salzwasserlagerungstest (5% NaCl solution, 40 ° C, 6 d, rockfall according to VDA 621-427 before and after)

Table 2: Results of test series 2

Examples 3a and 3b: MoO ₄ / ZrF ₆ rinse after conversion treatment with H ₂ ZrF ₆ / Sokalan HP56

Substrate: EG process sequence (immersion application):

Comparative Example 3a Conversion Treatment with H ₂ ZrF ₆ / Sokalan HP56 without Rinsing

Substrate: EG process sequence (immersion application):

Comparative Examples 3b and 3c: MoO ₄ rinse (without ZrF ₆ ) after conversion treatment with H ₂ ZrF ₆ / Sokalan HP56

Paint adhesion tests EC Alternating climate test VDA 621-415, 70 d; Rockfall according to VDA 621-427 before and after

Table 3: Results of test series 3

Example 4: MoO ₄ / Zr ₆ rinse with different pH after conversion treatment with H ₂ ZrF ₆ / Sokalan HP56

Substrate: EG process sequence (spray application):

Paint adhesion test: EC Salt water storage test (5% NaCl solution, 40 ° C, 6 d, rockfall according to VDA 621-427 before and after)

Comparative Example 4 Conversion Treatment with H ₂ ZrF ₆ / Sokalan HP56 without Rinsing

Substrate: EG process sequence (spray application):

Paint adhesion test: EC Salt water storage test (5% NaCl solution, 40 ° C, 6 d, rockfall according to VDA 621-427 before and after)

Table 4: Results of test series 4

Example 5: Method used as a rinse after conversion treatment

Substrate: CRS process sequence (immersion application):

Comparative Example 5a Conversion method as 5 without reactive rinse

Substrate: CRS process sequence (immersion application):

Comparative Example 5b: Nachspüle from 5 used as a conversion bath

Substrate: CRS process sequence (immersion application):

Table 5 Example 5

Claims (10)

Process for the two-stage corrosion protection treatment of metal surfaces, in which the metal surfaces a) are contacted in a first step with a chromium-free first aqueous solution with a pH in the range from 1.5 to 5, which has a total of at least 0.01 g / l, preferably at least 0.025 g / l, and up to 10 g / l, preferably up to 1 g / l, in particular up to 0.5 g / l of Ti and / or Zr and / or Si ions and at least one such amount fluoride contains the atomic ratio of Ti to F and / or Zr to F and / or Si to F in the range of 1: 1 to 1: 6, and thereafter, with or without intermediate rinsing with water, b) in a second step with a chromium-free second aqueous solution having a pH in the range of 1.5 to 5 brings in the total of at least 0.01 g / l, preferably at least 0.025 g / l, and up to 10 g / l, preferably to to 1 g / l, in particular up to 0.5 g / l of Ti and / or Zr and / or Si ions and at least one such amount of F luoride contains that the atomic ratio of Ti to F and / or Zr to F and / or Si to F in the range of 1: 1 to 1: 6, and in addition such an amount of soluble anions of oxo acids of molybdenum and / or tungsten in the oxidation state VI contains that the total concentration of molybdenum and / or tungsten, calculated as MoO ₄ ^2- and / or WO ₄ ^2- , is in the range of 5 to 1500 mg / l. Process for the preparation of a component containing painted metal parts, wherein: I) sheets of metal bearing a coating based on organic polymers are cut and / or punched and / or formed and the metal parts obtained thereby are assembled to produce the component, wherein areas of the metal surface of the sheet, which are not covered by the coating based on organic polymers; II) cleans the assembled component, III) subjecting the cleaned joined component to a process sequence which, on the areas of the metal surface which are not covered by the organic polymer-based coating in step I), produces a passivation layer which does not represent a zinc phosphate layer, wherein the areas of the metal surface of the sheet which are not covered by the organic polymer-based coating a) are contacted in a first step with a chromium-free first aqueous solution having a pH in the range of 1.5 to 5, the a total of at least 0.01 g / l, preferably at least 0.025 g / l, and up to 10 g / l, preferably up to 1 g / l, in particular up to 0.5 g / l Ti and / or Zr and / or or Si ions and at least one such amount of fluoride, that the atomic ratio Ti to F and / or Zr to F and / or Si to F in the range of 1: 1 to 1: 6, and thereafter, with or without intermediate rinsing with water, b) in a second step with a chromium-free second aqueous solution having a pH in the range of 1.5 to 5 brings in the total of at least 0.01 g / l, preferably at least 0.025 g / l, and contains up to 10 g / l, preferably up to 1 g / l, in particular up to 0.5 g / l of Ti and / or Zr and / or Si ions and at least one such amount of fluoride, that the atomic ratio of Ti to F and / or Zr to F and / or Si to F in the range of 1: 1 to 1: 6, and which additionally contains such an amount of soluble anions of oxo acids of molybdenum and / or tungsten in the oxidation state VI, that the Total concentration of molybdenum and / or tungsten, calculated as MoO ₄ ^2- and / or WO ₄ ^2- , in the range of 5 to 1500 mg / l, IV) if desired, but not necessarily the component treated in step c) on or rinsed several times with water and V) coated with a varnish layer. Method according to one or both of claims 1 and, characterized in that the metal surfaces are selected from surfaces of Steel, galvanized or alloy galvanized steel, aluminized steel, Zinc, aluminum, magnesium or alloys containing at least 50% Atomic percent of zinc, aluminum or magnesium. Method according to one or more of claims 1 to 3, characterized in that the first aqueous solution additionally at least 0.005 g / l, preferably at least 0.01 g / l, and up to 20 g / l, preferably contains up to 1 g / l of organic polymers. Method according to one or more of claims 1 to 4, characterized in that the second aqueous solution additionally contains complexing agents. Method according to one or more of claims 1 to 5, characterized in that the first and / or the second aqueous solution a pH of at least 1.5, preferably of at least 1.7, and up to 5, preferably up to 4 have. Method according to one or more of claims 1 to 6, characterized in that the second aqueous solution additionally buffer substances for the pH range Contains 1.5 to 5. Method according to one or more of claims 1 to 6, characterized in that the second aqueous solution is not more than 5 mg / l contains organic polymers. Method according to one or more of claims 1 to 7, characterized in that the metal surfaces in second step b) for a time in the range of 5 seconds to 10 minutes, preferably 10 seconds to one minute in contact with the second aqueous solution. Method according to claim 8, characterized in that that the second aqueous solution a temperature of at least 20 ° C, preferably at least 30 ° C, and not more than 60 ° C, preferably not more than 50 ° C having.