DE102004022565A1 - Colored conversion coatings on metal surfaces - Google Patents

Abstract

Chromium-free treatment solution for producing colored or fluorescent anticorrosion coatings on metal surfaces, which contains a) phosphoric acid and / or at least one fluoric acid of one or more elements of group B, Si, Ti, Zr and Hf or their anions and at least b) an organic polymer, wherein the organic polymer can bind to the metal surface via oxygen and / or nitrogen atoms, the organic polymer carrying covalently bonded coloring or fluorescent groups. A method of forming colored or fluorescent anti-corrosion coatings on metal surfaces by contacting the metal surfaces with such a processing solution. Metal part whose surface has a colored or fluorescent anti-corrosion layer obtainable by this process.

Description

The Invention is in the field of chemical surface treatment of zinc or galvanized steel, aluminum, magnesium or their Alloys. It describes chromium-free conversion methods for such Metal surfaces, d. H. chemical treatment processes leading to the formation of a surface layer, in the cations of the treated metal surface as well as ions from the Treatment solution installed become. The chromium-free coating is colored, so by simple visual control can be established if sufficient Conversion layer was formed. The task of this conversion layer is it to reduce the corrosion tendency of the metal surface and a good adhesion between the metal surface and one on the conversion layer applied organic coating such as a Make paint or an adhesive.

• a) 10 bis 16 g/l Polyacrylsäure oder deren Homopolymere,
• b) 12 bis 19 g/l Hexafluorozirkonsäure,
• c) 0,17 bis 0,3 g/l Fluorwasserstoffsäure und
• d) bis zu 0,6 g/l Hexafluorotitansäure.

For the production of chromium-free conversion coatings on the mentioned metal surfaces there is a comprehensive state of the art:
US-A-5 129 967 discloses treatment baths for no-rinse treatment (referred to therein as "dried in place conversion coating") of aluminum containing

• a) 10 to 16 g / l of polyacrylic acid or its homopolymers,
• b) 12 to 19 g / l hexafluorozirconic acid,
• c) 0.17 to 0.3 g / l hydrofluoric acid and
• d) up to 0.6 g / l hexafluorotitanic acid.

• a) 0,5 bis 10 g/l Polyacrylsäure oder eines Esters davon und
• b) 0,2 bis 8 g/l an mindestens einer der Verbindungen H₂ZrF₆, H₂TiF₆ und H₂SiF₆, wobei der pH-Wert der Lösung unterhalb von 3,5 liegt.

EP-B-8 942 discloses treatment solutions preferably containing aluminum cans

• a) 0.5 to 10 g / l of polyacrylic acid or an ester thereof and
• b) 0.2 to 8 g / l of 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 that are similar treatment baths can be used are listed in WO 02/20652.

• a) Phosphationen im Konzentrationsbereich zwischen 1,1×10^-5 bis 5,3×10^-3 mol/l entsprechend 1 bis 500 mg/l,
• b) 1,1×10^-5 bis 1,3×10^-3 mol/l einer Fluorosäure eines Elements der Gruppe Zr, Ti, Hf und Si (entsprechend je nach Element 1,6 bis 380 mg/l) und
• c) 0,26 bis 20 g/l einer Polyphenolverbindung, erhältlich durch Umsetzung von Poly(vinylphenol) mit Aldehyden und organischen Aminen.

US-A-4 992 116 describes treatment baths for the conversion treatment of aluminum with pH values between about 2.5 and 5, containing 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) 1.1 × 10 ^-5 to 1.3 × 10 ^-3 mol / l of a fluoro acid of an element of the group Zr, Ti, Hf and Si (corresponding to 1.6 to 380 mg / l depending on the element) and
• c) 0.26 to 20 g / l of a polyphenol compound obtainable by reaction of poly (vinylphenol) with aldehydes and organic amines.

WO 92/07973 teaches a chromium-free treatment process for aluminum containing, as essential components in acidic aqueous solution, from 0.01 to about 18% by weight of H ₂ ZrF ₆ and from 0.01 to about 10% by weight of a 3- (NC _{1 4-} alkyl-N-2-hydroxyethylaminomethyl) -4-hydroxystyrene polymer. Optional components are 0.05-10% by weight of dispersed SiO ₂ , 0.06-0.6% by weight of a solubilizer for the polymer, and surfactant. Said polymer falls under the group of "reaction products of poly (vinylphenol) with aldehydes and organic hydroxyl group-containing amines" described below and usable in the context of the present invention.

• a.) 0,5 bis 100 g/l Hexafluoroanionen des Titan (IV), Silicium (IV) und/oder Zircon (IV)
• b.) 0 bis 100 g/l Phosphorsäure
• c.) 0 bis 100 g/l einer oder mehrerer Verbindungen des Cobalts, Nickels, Vanadiums, Eisens, Mangans, Molybdäns oder Wolframs.
• d.) 0,5 bis 30 Gew. % mindestens eines wasserlöslichen oder wasserdispersierbaren filmbildenden organischen Polymers oder Copolymers (bezogen auf Aktivsubstanz),
• e.) 0,1 bis 10 Gew. % einer Organophosphonsäure
• f.) ggf. weitere Hilfs- und Zusatzstoffe.

WO 00/71626 discloses a chromium-free corrosion inhibitor containing water and

• a.) 0.5 to 100 g / l hexafluoro anions of titanium (IV), silicon (IV) and / or zirconium (IV)
• b.) 0 to 100 g / l phosphoric acid
• c.) 0 to 100 g / l of one or more compounds of cobalt, nickel, vanadium, iron, manganese, molybdenum or tungsten.
• d.) 0.5 to 30% by weight of at least one water-soluble or water-dispersible film-forming organic polymer or copolymer (based on the active substance),
• e.) 0.1 to 10% by weight of an organophosphonic acid
• f.) If necessary, further auxiliaries and additives.

In the above-mentioned documents, it is obvious in many cases that the conversion layers produced are colorless and translucent, so that the treated metal surfaces appear metallic bright. At a minimum, these documents do not disclose that colored layers would be formed. From the many years of experience with the chromating of metal surfaces, it is the expert However, this field is accustomed to obtain a colored layer as a result of the conversion treatment. He can then immediately visually recognize whether the treatment has brought the desired success. When producing colorless layers, however, a more complex surface analysis is required for this purpose, for example the determination of the Ti or Zr content of the surface by an X-ray fluorescence measurement. Therefore, there is a need in the art for surface treatment methods which not only have similar good corrosion protection and paint adhesion properties to conventional chromating layers, but are similar to chromating layers visible to the human eye.

Approaches to solution this task exist in the prior art. For example WO 94/25640 discloses a method of producing blue colored conversion layers on zinc / aluminum alloys. Here you bring the metal surfaces a treatment solution in touch, which has a pH between 3.5 and 6 and 0.2 to 3.0 Wt .-% molybdenum and has a fluoride content of 0.1 to 2.0 wt .-%. Molybdenum can as Molybdate, as phosphomolybdic acid, as molybdenum chloride and similar be used. Fluoride can be in the form of hydrofluoric acid, but simple fluorides, however also complex fluoro acids such as fluorotitanic acid or fluorozirconic acid be used.

The The teaching of WO 00/26437 goes the way, the conversion layer by to color an organic dye (Alizerin dye). The Conversion layer itself is produced with a treatment solution, the complex fluorides, for example, of titanium and zirconium beside other inorganic oxides, hydroxides or carbonates or their Reaction products containing the fluoro acids. In addition, as an organic polymer an amino-substituted poly-4-hydroxy-styrene (polyvinylphenol) to be present.

In FR 2 461 764 a chemical oxidation of the aluminum surface with organic nitro compounds in alkaline solution is proposed. After this oxidation, the layers can be dyed with an organic dye. A similar two-stage process proposes WO 01/71060. This document describes a multi-layer coating of a conversion layer applied to a metal (which can be obtained, for example, by electrochemical means and which has pores) and a colored layer located on this conversion layer. The second colored layer can be obtained by contact with a solution containing at least one alkoxysilane compound and a dye, followed by subsequent polymerization and / or crosslinking of the alkoxysilane compound.

The cited above for producing chromium-free colored Allow conversion layers on metals such as aluminum divide into 2 groups. In the first case, in the conversion layer colored transition metal compounds such as Molybdate or Polymolybdate or organic Dyes incorporated. On the other hand, in a conventional manner, a conversion layer produced and the organic dyes are on the already formed Conversion layer applied in a second step. It seems no example of a conversion treatment of metal surfaces too wherein the conversion treatment in the presence of an organic Polymer takes place, on the one hand the corrosion protection effect and the paint adhesion of the conversion layer reinforced and the other coloring substituent wearing, so that the presence of this polymer on the metal surface with can be recognized by the eye.

In the field of the treatment of circulating water, for example of industrial cooling systems, it is known to add organic polymers to prevent corrosion or deposits. Here is the task of monitoring the concentration of these polymers in the circulating water. The EP 504 520 proposes for this purpose to covalently bond dye residues to the organic polymers used for this purpose, so that the concentration of the polymers in the circulating water can be easily determined by absorption or fluorescence measurement. This document discloses a series of organic dye residues as well as monomers that can be reacted with each other and polymerized to obtain polymers having colorant groups. For example, these polymers may contain one or more of the following monomers: acrylic acid, acrylamide, sulfomethylacrylamide, vinyl acetate, methacrylic acid or acrylonitrile.

The The present invention has as its object, means and methods for producing chromium-free conversion layers on metal surfaces disposal with conversion layers in a single step which appear colored to the human eye or visibly fluoresce. In this case, none of the actual conversion active ingredients independent Dye can be used, otherwise it can not be guaranteed that the intensity the coloring or the fluorescence with the starch the conversion layer correlates.

• a) Phosphorsäure und/oder mindestens eine Fluorosäure eines oder mehrerer Elemente der Gruppe B, Si, Ti, Zr und Hf oder jeweils deren Anionen sowie mindestens
• b) ein organisches Polymer enthält, wobei das organische Polymer über Sauerstoff- und/oder Stickstoffatome an die Metalloberfläche binden kann, dadurch gekennzeichnet, dass das organische Polymer kovalent gebundene Gruppen trägt, die dem menschlichen Auge farbig erscheinen oder die beim Bestrahlen mit UV-Licht für das menschliche Auge erkennbar fluoreszieren.

This object is achieved by a chromium-free treatment solution for producing colored or fluorescent anticorrosive coatings on metal surfaces, the

• a) phosphoric acid and / or at least one fluoro acid of one or more elements of group B, Si, Ti, Zr and Hf or their anions and at least
• b) contains an organic polymer, wherein the organic polymer can bind to the metal surface via oxygen and / or nitrogen atoms, characterized in that the organic polymer carries covalently bonded groups that appear colored to the human eye or when irradiated with UV light fluorescently recognizable to the human eye.

By definition, the treatment solution free of chromium, i. contains no deliberately added chromium compounds. Traces of chrome can however, they are not excluded as impurities, for example as a result of a detachment from container material. Furthermore contains they also preferably no heavy metal ions other than those Components a) listed. This reduces the claims to the treatment of wastewater.

Especially should the treatment solution not more than 3 g / l of phosphoric acid and more than 0.3 g / l at the same time Contain zinc and / or manganese ions. This avoids that zinc and / or manganese phosphate crystals deposit on the metal surface. This would a more or less complete layer-forming Phosphating correspond, which is within the scope of the present invention undesirable is.

• a) 0,02 bis 20 g/l Phosphorsäure und/oder mindestens eine Fluorosäure eines oder mehrerer Elemente der Gruppe B, Si, Ti, Zr und Hf oder jeweils deren Anionen und
• b) 0,1 bis 200 g/l des organischen Polymers

enthält.A preferred treatment solution is characterized in that it

• a) 0.02 to 20 g / l phosphoric acid and / or at least one fluoro acid of one or more elements of the group B, Si, Ti, Zr and Hf or their anions and
• b) 0.1 to 200 g / l of the organic polymer

contains.

If the treatment solution phosphoric acid contains is their minimum concentration preferably at least 1 g / l, in particular at least 5 g / l. The upper limit of the concentration is 15 g / l in usually enough.

Contains the treatment solution as Component a) a fluoro acid of boron, for example, tetrafluoroboric acid, so its concentration preferably chosen such that the treatment solution at least 0.01 g / l, preferably at least 0.02 g / l, and up to 5 g / l, preferably up to 1 g / l and in particular up to 0.5 g / l Boron (calculated as element) contains. contains they are fluoro acids of hafnium, for example as hexafluoric acid, so you select their concentration preferably such that the treatment solution is at least 0.02 g / l, preferably at least 0.5 g / l, and up to 10 g / l, preferably up to 5 g / l and in particular up to 1 g / l hafnium.

Particularly preferred are treatment solutions containing as component a) fluoro acids of Si, Ti and / or Zr. Preferably, a treatment solution is used, 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 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. 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 hexafluorozirconations and (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, such an amount of Ti, Zr and / or Si is used as the central metal and an amount of fluoride such 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.

Especially preferred are treatment solutions, the fluoro acids of Ti and / or Zr. It may be for the corrosion protection effect very cheap be when the treatment solution both fluoro acids of Ti and Zr. The molar ratio can be from Ti to Zr in the range of 10: 1 to 1:10, especially in the range from 2: 1 to 1: 2.

Of the pH of the treatment solution should not be significantly lower than 1 because lower ones pH levels become increasingly stronger Pickling attack on the metal surface to lead. Preferably, the pH is not less than 2, and in particular not less than 2.5. At pH values above 6, the Formation of the conversion layer is no longer to the desired extent. Preferably one works at pH values not higher than 4 and in particular not higher as 3.5.

The mentioned essential components a) and optionally also b) represent all the protolytes, so molecules or ions that under release or uptake of protons in the sense of an acid-base reaction can. For the It is thus obvious to a person skilled in the art that these components are such React with each other and with the solvent water, until the corresponding chemical equilibria are reached. In the stated range of pH values it is expected that all these Protolytes in a partially protolysed state, regardless of whether they are in the form of their acids or their salts has been introduced into the treatment solution. Preferably if the stated pH values are in the acidic range, in that the phosphoric acid and / or complex fluoro acids in Form of the free acids brings. An additional Acid to Adjusting the acidic pH is then not necessary. however could These complex fluoride ions or phosphoric acid in the form of their salts use and by adding another acid such as nitric acid the desired Adjust pH. If necessary, lift the pH, for example, alkalis such as NaOH or ammonia are suitable.

The Concentration of the organic polymer b) is in the treatment solution preferably in the range between 0.1 and 200 g / l. This is the special preferred minimum concentration with increasing preference: at least 1 g / l, at least 5 g / l, at least 10 g / l, at least 15 g / l. As the upper limit of the concentration can be chosen with increasing preference: 150 g / l, 100 g / l, 70 g / l.

For the concentrations the active components a) and b) is generally that falls below the minimum concentration gradually decreases the quality of the coating. A crossing the said maximum concentration usually harms not, but brings no significant benefits and is therefore uneconomical.

In the organic polymer b) is the proportion by weight of the covalently bound groups corresponding to the human Eye appear colored or when irradiated with UV light for human Eye fluorescently, based on the total weight of the organic polymer at least 0.1, preferably at least 0.5 and in particular at least 1 wt .-% and up to 20, preferably up to 15 and in particular to to 10% by weight.

The Organic polymer b) may be selected from different groups. Preferably, the organic polymer is selected from epoxy resins, aminoplast resins, Phenol-aldehyde resins, carboxylic acid groups supporting polymers, polymeric alcohols, esterification products of polymeric alcohols with polymers carrying carboxylic acid groups, Amino-containing polymers, homopolymers or copolymers of vinylpyrrolidone and of polymers with phosphinic, phosphonic or phosphoric acid ester groups.

In the case of phenol-aldehyde resins, formaldehyde resins are preferred. In particular, amino-substituted poly-4-vinylphenol compounds are selected as polymers carrying amino groups. Examples of such poly-4-vinylphenol compounds without covalently bound coloring group, the above-cited WO 00/26437 and the literature cited therein such as in particular US 5,281,282 be removed.

• e) Polyvinylalkohol oder wasserlöslicher oder wasserdispergierbarer Partialester hiervon,
• f) Polymeren oder Copolymeren von ungesättigten Mono- oder Dicarbonsäuren oder deren Amiden,
• g) Ester aus den Polymeren der Gruppen e) und f),
• h) Polymere oder Co-Polymere von Vinylpyrrolidon,
• i) Polymeren des Diglycidylethers von Bisphenol A,
• k) Copolymeren aus Alkylenphosphon- oder Alkylenphosphinsäuren und einer oder mehreren ungesättigten Carbonsäuren.

Furthermore, the organic polymers b) may be selected with regard to their polymeric backbone from:

• e) polyvinyl alcohol or water-soluble or water-dispersible partial ester thereof,
• f) polymers or copolymers of unsaturated mono- or dicarboxylic acids or their amides,
• g) esters of the polymers of groups e) and f),
• h) Polymers or copolymers of vinylpyrrolidone,
• i) polymers of the diglycidyl ether of bisphenol A,
• k) copolymers of alkylenephosphonic or alkylenephosphinic acids and one or more unsaturated carboxylic acids.

at the polymer of group e) is understood by a "partial ester" that only a part of the alcohol groups esterified, wherein the ester formation is carried out with non-polymeric carboxylic acids. In particular, the esterification with monobasic carboxylic acids with 1 to 4 carbon atoms take place.

The For example, polymers or copolymers of group f) may be selected from homo- or copolymers of acrylic acid and / or methacrylic acid, their acid groups partially replaced by amide groups or esterified with alcohols could be, in particular with simple alcohols having 1 to 4 carbon atoms. Specific Examples are homo- or copolymers of or with methyl methacrylate, n-butyl acrylate, hydroxyethyl acrylate and glycerol propoxitriacrylate. These specific examples are known, for example, from WO 95/14117. The polymers of group f) can still selected from those containing maleic acid monomers. A special example of this is a maleic acid methyl vinyl ether copolymer.

polymers Group e) usually contain free alcohol groups, such the group f) free carboxylic acid groups. Therefore, these two polymers can not only be mixed with each other but in a form in which between the alcohol groups of the polymer e) and the carboxylic acid groups the polymer f) at least partially esterification occurred is. Closer explained this is in WO 94/12570. The teaching described there is also in the Usable in the context of the present invention.

Farther can the treatment solution Contain polymers of group h). Such polymers and their use in treatment solutions for the Conversion treatment are described in DE-A-100 05 113 and DE-A-101 31 723 described in more detail.

Farther can the additional Polymers selected from those of group i), as described in more detail in US-A-5,356,490 is.

Especially organic polymers b) are preferred which, in terms of their polymeric Backbones are selected from polymers or copolymers of acrylate and / or methacrylate monomers, maleic anhydride, which may be completely or partially hydrolyzed (in particular methylvinyl ether-maleic anhydride copolymers) and acrylate or methacrylate monomers that terminate with phosphate groups are. Specific examples of this are mentioned in the experimental part.

The covalently bonded groups in the organic polymer b) corresponding to the human eye appear colored or when irradiated with UV light for the human eye detectable fluoresce, are preferably selected made of Tuloidin Blue (CAS No. 92-31-9) and Neutral Red (CAS no. 553-24-2).

The average molecular weight of the organic polymers a) is preferably at least 10 000 daltons. The upper limit of the molecular weight is not critical as long as the polymer in the preferably acidic treatment solution in desired Concentration range soluble or dispersible. For example, the upper limit of the molecular weight at 50,000,000, in particular at 20,000,000 and more preferred at 10 000 000 daltons. Also a cap of 5 000 000 Dalton may be enough. The average molecular weight is preferably greater than 50,000 daltons and in particular greater than 100,000 daltons. The mean molecular weights can be determined, for example, by gel permeation chromatography with polyethylene glycol standard.

As organic polymer b), preference is given in particular to a copolymer of i) acrylic acid and / or methacrylic acid with ii) acrylate and / or methacrylate monomers which are terminated by phosphate groups, the copolymer containing covalently bonded molecules of toluidine blue or neutral red. An exemplary preparation of this polymer is described in Example 3, another example in Example 10. These polymers are examples of polymers which have both carboxylate and phosphonic acid groups or phosphoric acid ester groups. Because of their high affinity to metal surfaces These polymers with different polar adhesion groups are particularly preferred. Such particularly preferred copolymers can also be obtained, for example, by reacting acrylic acid and / or methacrylic acid with other unsaturated phosphonic acids, phosphinic acids or phosphoric acid esters. For example, as the unsaturated monomer having a phosphonic acid group, vinylphosphonic acid can be used.

The Applicant has not been able to find a document of the prior art in which the most preferred copolymer of i) acrylic acid and / or methacrylic acid with ii) acrylate and / or methacrylate monomers with phosphate groups terminates the covalently bound molecules of Tuloidin Blue or Neutral Contains red, is described. Therefore, this copolymer itself also forms an object of the present invention. With regard to the preferred Molar masses apply the statements made above. Likewise apply the further statements made above to the mass fraction of the dye groups on the total mass of the polymer. The weight ratio between the monomers i) and the monomers ii) is preferably in the range from 10: 1 to 1:10, in particular from 5: 1 to 1: 5 and more preferably in the range of 3: 1 to 1: 1.

One further for the treatment solution according to the invention is preferred Polymer is a methyl vinyl ether-maleic anhydride copolymer to which molecules are covalently bound by toluidine blue or neutral red and its Anhydride groups at least partially, preferably at least 90% hydrolyzed. The molar ratio of the monomeric methyl vinyl ether and maleic anhydride is preferably in the range of 10: 1 to 1:10, in particular from 5: 1 to 1: 5, more preferably from 1: 2 to 2: 1. For example the molar ratio be substantially 1: 1.

In addition, can the watery treatment solution as further component c) a total of 1 to 2,000 mg / l of one or contain several chelating complexing agents that are not under the definition of the organic polymers of group b) fall. there the chelating complexing agent c) is preferably not polymeric and preferably selected from molecules with 2 or more phosphonic acid groups, in particular from geminal diphosphonic acids, and phosphonocarboxylic acids and each of their anions. (As explained above, the treatment solution and in the concentrate, depending on the pH, the corresponding acid-base balance between acid form and salt form of the complexing agent, regardless of, in which form you put him in the solution or the concentrate has been introduced.)

Examples Such complexing agents are those which are also according to DE-A-103 39 165 can be used. Reference is hereby made to this reference.

The Properties of the obtained conversion layer can in Case, if the treatment solution (regardless of whether said component c) is also present or not) as additional Component d) at least one inorganic compound in particle form with a mean particle diameter, measured with a scanning electron microscope, in the range of 0.005 to 0.2 microns Diameter contains.

The inorganic compound in particulate form is in the aqueous bath solution preferably in a content of 0.1 to 80 g / l, especially preferably in a range of 0.2 to 25 g / l, most preferably from 0.5 to 10 g / l, especially from 1 to 4 g / l.

The relationship the contents of organic polymer b) to levels of inorganic Compounds in particulate form in the aqueous bath solution can in wide ranges, in particular, it may be ≤ 3.8: 1. Preferably, this ratio in a range from 0.05: 1 to 3.5: 1, more preferably in a range of 0.18: 1 to 2.5: 1.

In the method according to the invention, a finely divided powder, a dispersion or a suspension is added as the inorganic compound in particle form, for example a carbonate, an oxide, a silicate or a sulfate, in particular colloidal or amorphous particles. As the inorganic compound in particle form, particles based on at least one compound of aluminum, barium, cerium, calcium, lanthanum, silicon, titanium, yttrium, zinc or / and zirconium are particularly preferred, in particular particles based on alumina, barium sulfate, ceria, rare earth mixed oxide , Silica, silicate, titania, yttria, zinc oxide or / and zirconia. Preferably, the at least one inorganic compound is present in particulate form in particulate with an average particle size in the range of 6 nm to 150 nm, more preferably in the range of 7 to 120 nm, most preferably in the range of 8 to 90 nm, even more preferably in Range from 8 to 60 nm, to 25 nm. It is preferred that larger particles have a rather platelike or have elongated grain shape.

In the case, that coated according to the invention and possibly also provided with paint or paint-like coatings welded metallic substrates should be advantageous, as Partikei the connection in particle form those with higher or high electrical conductivity use, in particular those of oxides, phosphates, phosphides or sulfides of aluminum, iron or molybdenum, in particular aluminum phosphide or, iron oxide, iron phosphide, at least one molybdenum compound like molybdenum sulphide, Graphite and / or carbon black, these Partikei then also have such an average particle size can, that they possibly protrude slightly stronger from the layer produced according to the invention.

In In another aspect, the present invention relates to a method for producing colored or fluorescent anticorrosive coatings on metal surfaces, characterized in that the metal surfaces for a period of time in the range of 0.5 to 10 minutes in contact with a treatment solution after one or more of the claims 1 to 8, which has a temperature in the range of 20 to 80 ° C.

there can the metal surface with the treatment solution according to common in the art Methods such as dipping, spraying, a combination of spray and dipping, rolling, etc. are brought into contact. After this Contact with the treatment solution become the metal surfaces preferably with water, in particular with demineralized water rinsed and subsequently according to common Process dried. The contact time is preferably at least 1 minute, in particular at least 2 minutes. A contact time of up to 7 minutes, for example up to 5 minutes is in the Usually sufficient.

A no-rinse treatment, i. one application (roller application, spray application with squeezing) without rinsing is also possible. The temperature of the treatment solution is preferably at least 30 ° C, for example 35 ° C. In general, it is not necessary that the temperature of the Treatment solution one Upper limit of 60 ° C, especially exceeds 50 ° C.

The metal surfaces which can be treated by the method according to the invention are preferably selected from surfaces of aluminum and aluminum alloys, magnesium and magnesium alloys, titanium and titanium alloys, zinc and zinc alloys, galvanized or alloy galvanized steel. The metal surfaces may be surfaces of the metals mentioned or their alloys as such, but also surfaces of a substrate such as steel, which is coated with the metals or their alloys. Examples of the latter are electrolytically galvanized or hot dip galvanized steel, aluminized steel, or coated steel as Galvalume ^® or Galfan ^®, which carry a coating of zinc / aluminum alloys.

Finally, concerns the invention in a further aspect, a metal part, the surface of a having colored or fluorescent anticorrosive coating, such as it is obtainable by the process according to the invention. The above statements apply to the most preferred Metals accordingly. In this case, the metal part as the only or as the outermost coating have the colored or fluorescent corrosion protection layer, with the method according to the invention available is. The inventive method however, usually serves as a pretreatment for a further coating, For example, a coating with a paint or with a Adhesive when treated metal parts with each other or with to be glued to other substrates. Accordingly, the metal part according to the invention as the outermost layer have a lacquer or can with another metal part according to the invention or be glued to another substrate.

Of the inventive treatment step is usually part of a course of treatment, as with a Conversion treatment of said metal surfaces before a subsequent Coating or bonding usual is. Such a sequence usually begins with a Cleaning / degreasing of the metal surfaces, for example, an alkaline Cleaner can be used. This is followed by one or more rinsing steps with water on. This may be followed by an acidic treatment step for removal superficial Oxides are not removed during the alkaline cleaning become. This step is also referred to as "deoxidizing" or "picking" and especially in surfaces of Aluminum and its alloys used. After an intermediate rinse with Water and preferably an additional rinse with demineralized water This is followed by the treatment step according to the invention with the treatment solution according to the invention. hereafter can be rinsed again with water become. However, the method can also be performed as a "no-rinse" method, i. on a rinse with Water after the treatment step according to the invention can also be dispensed with.

As a result of this treatment sequence, a colored or fluorescent, corrosion-protected metal surface is obtained which exhibits good adhesion to a subsequently applied layer based on organic polymers, for example a lacquer or an adhesive. This surface usually contains 1 to 70 mg of titanium and / or zirconium per m ² , in particular 3 to 30 mg / m ² , if the fluoro acids of these metals were used as component a). These values can be measured by conventional methods of surface analysis, for example by X-ray fluorescence methods.

The inventive method delivers metal surfaces, which have a good corrosion protection and a good paint adhesion, as the skilled person as a result of the technically very advantageous, from ecological and health reasons however unwanted Chromatierverfahren knows. Due to the coloring of the surface looks the expert immediately, whether in the treatment of a sufficient Conversion layer has formed, as it is from the chromating used to it is. The inventive method so has opposite producing colorless conversion layers has the technical advantage that the result the treatment is immediately visually recognizable without a special surface analysis must be used.

embodiments

Example 1: Preparation a toluidine blue monomer

3g Toluidine Blue (CAS No. 92-31-9) is dissolved in 50 ml of water and washed with 200ml pyridine mixed. Under ice-cooling, the solution becomes dropwise with 1.1 g of methacrylic acid chloride offset and for one hour and 3 hours at 40 ° C touched. The solvent is distilled off in vacuo.

It 3.8 g of the crude product were obtained.

Example 2: Preparation a neutral red monomer

3g Neutral Red (CAS # 553-24-2) are dissolved in 50ml of water and mixed with 200ml pyridine mixed. Under ice-cooling, the solution becomes dropwise with 1.1 g of methacrylic acid chloride offset and for one hour and 3 hours at 40 ° C touched. The solvent is distilled off in vacuo.

It 3.7 g of the crude product were obtained.

Example 3: Polymerization I

0.2g Toluidine blue monomer, 13.8 g acrylic acid and 6 g methacrylate monomer, terminated with phosphate groups (Sipomer PAM100, Rhodia) dissolved in 300ml of water and deoxygenated by introducing nitrogen at 50 ° C for 30 min. Subsequently the polymerization is started by adding 0.1 g of V-44 (initiator). The solution is for 24 hours at 50 ° C touched, followed by another 0.1 g V-44 and polymerized for a further 24 hours. Restart with 0.1 g of V-50 (initiator), increase the reaction temperature 80 ° C and stir for further 4 hours. The colored polymer solution is for Dialysed for 48 hours (dialysis tubing with exclusion limit of 10,000 Dalton).

To Dialysis was 670ml of a 2.4% colored solution, which received a 80% yield corresponds.

Example 4: Polymerization II

0.2g Toluidine blue monomer, 13.8g acrylic acid and 6g vinylphosphonic acid dissolved in 300ml of water and deoxygenated by introducing nitrogen at 50 ° C for 30 min. Subsequently the polymerization is started by adding 0.1 g of V-44 (initiator). The solution is for 24 hours at 50 ° C stirred, with followed by another 0.1 g of V-44 and polymerized for a further 24 hours. Restart with 0.1 g V-50 (initiator), increase the reaction temperature at 80 ° C and stirring for further 4 hours. The colored polymer solution is for Dialysed for 48 hours (dialysis tubing with exclusion limit of 10,000 Dalton).

To Dialysis was 470ml of a 3% colored solution, which received a Corresponds to 70% yield.

In gel permeation chromatography, an average molecular weight M _w = 45,000 was obtained. The GPC column was calibrated with a polyacrylate standard.

Example 5: Reaction of toluidine blue with methyl vinyl ether-maleic anhydride copolymers

0.1 g of toluidine blue are dissolved in 300 ml of a water / ice mixture. Then, with vigorous stirring, 10 g of maleic anhydride-methyl vinyl ether copolymer (Gantrez AN-119, GAF General Aniline Firm Corp.) (M _w = 216000 g / mol) are added and stirred for 24 hours. For complete hydrolysis of the anhydride groups, the solution is heated to 80 ° C for 2 hours. To remove the unreacted dye molecules, the solution was dialyzed for 48 hours (10,000 dalton exclusion dialysis tubing).

To Dialysis was obtained 400ml of a 0.31% colored solution.

Example 6: Reaction of toluidine blue with methyl vinyl ether-maleic anhydride copolymers

0.1 g of toluidine blue are dissolved in 380 ml of a water / ice mixture. Then, with vigorous stirring, 10 g of maleic anhydride-methyl vinyl ether copolymer (Gantrez AN-139, GAF General Aniline Firm Corp.) (M _w = 1080000 g / mol) are added and stirred for 24 hours. For complete hydrolysis of the anhydride groups, the solution is heated to 80 ° C for 2 hours. To remove the unreacted dye molecules, the solution was dialyzed for 48 hours (10,000 dalton exclusion dialysis tubing).

To Dialysis was obtained 400ml of a 2.34% colored solution.

Example 7: Reaction of toluidine blue with methyl vinyl ether-maleic anhydride copolymers

0.1 g of toluidine blue are dissolved in 300 ml of a water / ice mixture. Then, with vigorous stirring, 10 g of maleic anhydride-methyl vinyl ether copolymer (Gantrez AN-169, GAF General Aniline Firm Corp.) (M _w = 1980000 g / mol) are added and stirred for 24 hours. For complete hydrolysis of the anhydride groups, the solution is heated to 80 ° C for 2 hours. To remove the unreacted dye molecules, the solution was dialyzed for 48 hours (10,000 dalton exclusion dialysis tubing).

To Dialysis was obtained 400ml of a 2.4% colored solution.

Example 8: Reaction of toluidine blue with methyl vinyl ether-maleic anhydride copolymers

0.4 g of toluidine blue are dissolved in 380 ml of a water / ice mixture. Then, with vigorous stirring, 10 g of maleic anhydride-methyl vinyl ether copolymer (Gantrez AN-139, GAF General Aniline Firm Corp.) (M _w = 1080000 g / mol) are added and stirred for 24 hours. For complete hydrolysis of the anhydride groups, the solution is heated to 80 ° C for 2 hours. To remove the unreacted dye molecules, the solution was dialyzed for 48 hours (10,000 dalton exclusion dialysis tubing).

To Dialysis was obtained 400ml of a 2.24% colored solution.

Example 9: Reaction Neutral Red with methyl vinyl ether-maleic anhydride copolymers

0.1g Neutral Red are dissolved in 380ml of a water / ice mixture. Then, with vigorous stirring, 10 g of maleic anhydride-methyl vinyl ether copolymer (Gantrez AN-139, GAF General Aniline Firm Corp.) (M _w = 1080000 g / mol) are added and stirred for 24 hours. For complete hydrolysis of the anhydride groups, the solution is heated to 80 ° C for 2 hours. To remove the unreacted dye molecules, the solution was dialyzed for 48 hours (10,000 dalton exclusion dialysis tubing).

To Dialysis was obtained 400ml of a 2.1% colored solution.

Example 10: Polymerization III

0.2g neutral red monomer, 13.8g acrylic acid and 6g methacrylate monomer, with phosphate groups ter (Sipomer PAM100, Rhodia) are dissolved in 550 ml of water and freed from oxygen by passing in nitrogen at 50 ° C. for 30 min. Subsequently, the polymerization is started by adding 0.1 g of V-44 (initiator). The solution is stirred for 24 hours at 50 ° C, followed by another 0.1 g V-44 and polymerized for a further 24 hours. Start with 0.1 g of V-50 (initiator), increase the reaction temperature to 80 ° C. and stir for a further 4 hours. The colored polymer solution is dialyzed for 48 hours (dialysis tubing with exclusion limit of 10,000 daltons).

To Dialysis was obtained 650ml of a 2.39% colored solution, which was a 77% yield corresponds.

Pretreatment of aluminum substrates with chromium-free polymer solution (pH value: 2.7): Sample sheets of aluminum of the alloy AL 99.5 were pretreated prior to the treatment step according to the invention as is customary in the art:
Cleaning: spraying with an alkaline cleaner (Ridoline ^® C 72.2%, commercial product of the applicant) 65 ° C, 1 minute
Rinse: city water, room temperature, 1 minute
Rinse: Demineralized water, room temperature, 1 minute.

hereupon followed by the treatment step according to the invention in the dipping process as below.

To In the conversion treatment step, the sheets were heated at 60 ° C in a convection oven dried and then with a commercial Powder paint painted. Following this, a practice-standard paint adhesion test was carried out: The sample plates were crosshatched, 2 hours in boiling deionized water and then at room temperature for one hour stored. Then it was over Adhesive tape glued and peeled off the crosshatch area. The paint part removed from the sample sheet was evaluated and characterized by cross-cut notes: Gt 0: no paint loss, Gt 5: extensive paint loss. In addition, the paint infiltration was after salt spray test checked.

compositions the treatment solutions and treatment results are shown below.

Example 11:

• Composition of a 100 g aqueous treatment solution: H2TiF6 0.1 g polymer (Example 6) 2.55 g water 97.35 g

• a) 2min; Bleche erhielten nach Trocknen einen hellen Blauschimmer
• b) 5min; Bleche erhielten nach Trocknen einen gut sichtbaren Blauton

Dipping aluminum sheets in pretreatment

• a) 2min; Sheets were given a light blue color after drying
• b) 5min; Sheets were given a clearly visible shade of blue after drying

Example 12:

• Composition of a 100 g aqueous treatment solution: H2TiF6 0.1 g polymer (Example 6) 1 g water 98.9 g

• a) 2min; Bleche erhielten nach Trocknen einen sehr hellen Blauschimmer
• b) 5min; Bleche erhielten nach Trocknen einen sehr hellen Blauschimmer.

Dipping aluminum sheets in pretreatment

• a) 2min; Sheets were given a very light blue color after drying
• b) 5min; Sheets were given a very light blue color after drying.

Example 13:

• Composition of a 100 g aqueous treatment solution: H2TiF6 0.1 g polymer (Example 6) 1.25 g water 98.65 g

• a) 2min; Bleche erhielten nach Trocknen einen hellen Blauschimmer
• b) 5min; Bleche erhielten nach Trocknen einen hellen Blauschimmer.

Dipping aluminum sheets in pretreatment

• a) 2min; Sheets were given a light blue color after drying
• b) 5min; Sheets were given a light blue color after drying.

Example 14:

• Composition of a 100 g aqueous treatment solution: H2TiF6 0.1 g polymer (Example 7) 3.6 g water 96.3 g

• a) 2min; Bleche erhielten nach Trocknen einen dunklen Blauton
• b) 5min; Bleche erhielten nach Trocknen einen dunklen Blauton.

Dipping aluminum sheets in pretreatment

• a) 2min; Sheets were given a dark shade of blue after drying
• b) 5min; Sheets were given a dark shade of blue after drying.

Example 15:

• Composition of a 100 g aqueous treatment solution: H2TiF6 0.1 g polymer (Example 7) 1.8 g water 98.1 g

• a) 2min; Bleche erhielten nach Trocknen einen gut sichtbaren Blauton
• b) 5min; Bleche erhielten nach Trocknen einen gut sichtbaren Blauton.

Dipping aluminum sheets in pretreatment

• a) 2min; Sheets were given a clearly visible shade of blue after drying
• b) 5min; Sheets were given a clearly visible shade of blue after drying.

Example 16:

• Composition of a 100 g aqueous treatment solution: H2TiF6 0.1 g polymer (Example 7) 0.9 g water 99 g

• a) 2min; Bleche erhielten nach Trocknen keinen Blauton
• b) 5min; Bleche erhielten nach Trocknen einen sehr hellen Blauschimmer.

Dipping aluminum sheets in pretreatment

• a) 2min; Sheets did not get blue after drying
• b) 5min; Sheets were given a very light blue color after drying.

Example 17:

• Composition of a 100 g aqueous treatment solution: H2TiF6 0.1 g polymer (Example 3) 3.53 g water 96.37 g

• a) 2min; Bleche erhielten nach Trocknen einen gut sichtbaren Blauton
• b) 5min; Bleche erhielten nach Trocknen einen gut sichtbaren Blauton.

Dipping aluminum sheets in pretreatment

• a) 2min; Sheets were given a clearly visible shade of blue after drying
• b) 5min; Sheets were given a clearly visible shade of blue after drying.

Example 18:

• Composition of a 100 g aqueous treatment solution: H2TiF6 0.1 g polymer (Example 3) 1.8 g water 98.1 g

• a) 2min; Bleche erhielten nach Trocknen einen sehr hellen Blauschimmer
• b) 5min; Bleche erhielten nach Trocknen einen hellen Blauschimmer.

Dipping aluminum sheets in pretreatment

• a) 2min; Sheets were given a very light blue color after drying
• b) 5min; Sheets were given a light blue color after drying.

Example 19:

• Composition of a 100 g aqueous treatment solution: H2TiF6 0.1 g polymer (Example 10) 3.53 g water 96.37 g

• a) 2min; Bleche erhielten nach Trocknen einen gut sichtbaren Rotton
• b) 5min; Bleche erhielten nach Trocknen einen gut sichtbaren Rotton.

Dipping aluminum sheets in pretreatment

• a) 2min; Sheets were given a clearly visible shade of red after drying
• b) 5min; Sheets were given a clearly visible shade of red after drying.

Example 20:

• Composition of a 100 g aqueous treatment solution: H2TiF6 0.1 g polymer (Example 10) 1.8 g water 98.1 g

• a) 2min; Bleche erhielten nach Trocknen einen sehr hellen Rosaschimmer
• b) 5min; Bleche erhielten nach Trocknen einen hellen Rosaschimmer.

Dipping aluminum sheets in pretreatment

• a) 2min; Sheets were given a very light pink mash after drying
• b) 5min; Sheets were given a bright pink mash after drying.

Corrosion protection properties according to the invention pretreated and then painted sheets (AI 99.5 F 19).
Cleaning / Water Rinse: as above.

Tabelle 2: Testergebnisse an ausgewählten Blechen (vergleiche Tabelle 1): Salzsprühnebelprüfung nach DIN 50021 SS

Tabelle 3: Testergebnisse an ausgewählten Blechen (vergleiche Tabelle 1): Kochtest in VE-Wasser, 2 Stunden bei 100°C

The treatment solutions contained 1% by weight of H ₂ TiF ₆ and the amount of polymer mentioned in Table 1. Temperature: 35 ° C. Duration of treatment, pH of the treatment solution and tests: see Table 1; Test results: Tables 2 and 3
Drying: circulating air drying oven, 60 ° C
Lacquer: BASF standard, white
Powder paint, Ral 9010
Hardening: 20 minutes, 360 ° C
Paint thickness: See Tables 2 and 3.
Corrosion tests: See tables Table 1: Treatment parameters, tests performed

Table 2: Test results on selected sheets (compare Table 1): Salt spray test according to DIN 50021 SS

Table 3: Test results on selected sheets (compare Table 1): Cook in deionized water for 2 hours at 100 ° C

Claims (12)

Chromium-free treatment solution for producing colored or fluorescent anticorrosive coatings on metal surfaces, comprising a) phosphoric acid and / or at least one fluoric acid of one or more elements of group B, Si, Ti, Zr and Hf or in each case their anions and at least b) contains an organic polymer, wherein the organic polymer can bind to the metal surface via oxygen and / or nitrogen atoms, characterized in that the organic polymer carries covalently bonded groups which colored the human eye appear fluorescent or detectable when irradiated with UV light to the human eye. treatment solution according to claim 1, characterized in that they a) 0.02 to 20 g / l phosphoric acid and / or at least one fluoro acid one or more elements of group B, Si, Ti, Zr and Hf or respectively their anions and b) 0.1 to 200 g / l of the organic Polymers contains. treatment solution according to one or both of the claims 1 and 2, characterized in that they have a pH in the range from 1 to 6. treatment solution according to one or more of claims 1 to 3, characterized the proportion by weight of the covalently bonded groups corresponding to the human eye appear colored or when irradiated with UV light for to visibly fluoresce the human eye, the total weight of the organic polymer is 0.1 to 20 weight percent. treatment solution according to one or more of claims 1 to 4, characterized the organic polymer is selected from epoxy resins, aminoplast resins, Phenol-aldehyde resins, carboxylic acid groups supporting polymers, polymeric alcohols, esterification products of polymeric alcohols with polymers carrying carboxylic acid groups, Amino-containing polymers, homopolymers or copolymers of vinylpyrrolidone and of polymers with phosphinic, phosphonic or phosphoric acid ester groups. treatment solution according to claim 5, characterized in that the organic polymer selected is made of polymers of acrylate and / or methacrylate monomers, maleic anhydride, which may be wholly or partially hydrolyzed, acrylate or methacrylate monomers terminated with phosphate groups. treatment solution according to one or more of claims 1 to 6, characterized that the covalently bound groups are the human eye appear colored or when irradiated with UV light for the human Recognize visible eye, are selected from toluidine blue and neutral red treatment solution according to one or more of claims 1 to 7, characterized that they as additional Component d) at least one inorganic compound in particle form with a mean particle diameter, measured with a scanning electron microscope, in the range of 0.005 to 0.2 microns Diameter contains. Copolymer of a) acrylic acid and / or methacrylic acid with b) acrylate and / or methacrylate monomers terminated with phosphate groups, the covalently bound molecules of toluidine contains blue or neutral red. Method of producing colored or fluorescent Corrosion protection coatings on metal surfaces, characterized that one the metal surfaces for one Duration in the range of 0.5 to 10 minutes in contact with a treatment solution according to one or more of claims 1 to 8 brings the one Temperature in the range of 20 to 80 ° C. Method according to claim 10, characterized in that that the metal surfaces selected are made of surfaces of aluminum and aluminum alloys, magnesium and magnesium alloys, Titanium and titanium alloys, zinc and zinc alloys, galvanized or alloy-galvanized steel. Metal part whose surface is a colored or fluorescent Corrosion protection layer, which after one or both of the claims 10 and 11 available is.