WO2008092528A1

WO2008092528A1 - Pretreated metal with luminescent pigments

Info

Publication number: WO2008092528A1
Application number: PCT/EP2007/063648
Authority: WO
Inventors: Ina KRÜGERMANN; Christian Rosenkranz; Stefanie Küch
Original assignee: Henkel Ag & Co. Kgaa
Priority date: 2007-02-01
Filing date: 2007-12-11
Publication date: 2008-08-07
Also published as: DE102007005943A1; JP2010518185A

Abstract

The invention relates to an essentially chrome-free aqueous agent for the anti-corrosive treatment of metal surfaces containing a particulate inorganic pigment. The pigment luminates when irradiated with ultraviolet light and the pH-value of the aqueous substance has a maximum of 4 and a minimum of 1. The invention also relates to concentrates that act as a concentrate for the inventive substance or can be used directly for treating the metallic surfaces. The claimed method relates to the treatment of a metallic surface with said substance and to the optical distribution of the quality of the handling process using a luminescent of the metal surface that is as homogeneous as possible, such that the claimed inorganic pigment is surface-immobilised and impregnated into the protective layer prior to corrosion of the metallic layer. The invention also relates to method steps derived therefrom for optimising the treatment process and/or the layer quality.

Description

Metal pretreatment with luminescent pigments

The invention is in the field of chemical surface treatment of zinc or galvanized steel, aluminum, magnesium or their alloys. The present invention relates to a substantially chromium-free aqueous agent for the corrosion-protective treatment of metal surfaces containing a particulate inorganic pigment, wherein the pigment luminesces when irradiated with ultraviolet light and the pH of the aqueous agent is not greater than 4 and not less than 1 , Furthermore, concentrates according to the invention are included which either serve as a concentrate for the agent according to the invention or which can be used directly for the treatment of the metallic surface. The method according to the invention comprises treating a metallic surface with such a means and visually assessing the quality of the treatment process on the basis of a luminescence of the metal surface which is as homogeneous as possible, caused by the inorganic pigment according to the invention immobilized in the protective layer against corrosion of the metallic substrate and / or superficially immobilized , Such an optical assessment of the anticorrosive treatment, wherein the luminescence of the treated metal surface is preferably in the visible range of the light and is perceptible to the human eye, opens up various possibilities of aftertreatment, which are without the presence of the luminescent pigments in the corrosion-protecting organic-inorganic hybrid layer, are not possible in the technical coating process and therefore represent a further aspect of this invention.

The chemical treatment of metallic surfaces to impart corrosion protection essentially comprises phosphating and conversion processes, the latter forming extremely thin and amorphous mostly inorganic cover layers which do not cause any visible change of the metallic surface to the human eye. The occurrence of interference colors can usually only be observed for layer thicknesses above 100 nm, wherein due to the strong dependence of the interference color on the viewing angle, no uniform overall impression of the corrosion-protected treated metal surface results. Only the chromating as a passivating conversion treatment produces intensely colored metal surfaces. From many years of experience with the chromating of metal surfaces, it is therefore familiar to the person skilled in the art 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. Since chromating is to be replaced by chromium-free alternative conversion processes due to the toxicity of the chemicals used and existing European Directives (2000/53 / EC, 2005/673 / EC), there is a need for treatment baths and processes which are typical of the particular treatment cause optically visible change in the metal surface. A complex surface-analytical examination of colorless layers, for example by X-ray fluorescence measurements, is routinely applied very cost-intensive and also has only the character of a random quality control.

In the prior art typical corrosion-protective treatment method for metallic surfaces that produce colorless conversion layers are described in the applications WO 00/71626 and the still unpublished DE 102005059314.3. By conversion of a metallic surface, the person skilled in the art understands the deposition of a mostly almost completely inorganic and amorphous covering layer initiated by a pickling attack of the metallic substrate. This conversion layer is composed of both anions and cations of the treatment agent as well as cations of the metallic substrate, which are dissolved out during the conversion of the surface by the pickling attack and partly incorporated in the layer with. In addition, the conversion bath usually contains organic polymeric compounds which usually have complexing properties, but do not exclusively have a stabilizing effect on the bath components, but are also selected such that they exert a positive influence on the adhesion of further applied organic coating systems as a constituent of the conversion layer. Conversion layers therefore represent organic-inorganic hybrid layers, wherein the organic content of the respective composition of the conversion agent and the method of application thereof within a wide range is adjustable.

WO 00/71626 discloses a chromium-free corrosion inhibitor containing water and a) 0.5 to 100 g / l hexafluoroanion 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. O

d) 0.5 to 30 wt .-% of at least one water-soluble or water-dispersible film-forming organic polymer or copolymer, e) 0.1 to 10 wt .-% of an organophosphonic acid f) optionally further auxiliaries and additives.

The conversion treatment is carried out here in the "dry-in-place" process, so that the proportion of organic polymers in the conversion layer can be adjusted with the polymer content in the treatment agent.

The still unpublished German application DE102005059314.3 describes a "wet-in-wet" process for the corrosion protection treatment of metal surfaces, wherein the metal surfaces with an acidic aqueous solution of a fluoro-complex of at least one element selected from the group B, Si, Ti, Zr and Hf additionally contains a small amount of a polyallylamine, as well as various metal ions such as copper (II) ions, aromatic carboxylic acids and particulate silica In this "wet-in-wet" process, a conversion coating is produced which is nearly complete consists of inorganic constituents and which is provided immediately after the treatment and without intervening drying step with an electrodeposition paint.

It is evident in the above-mentioned documents that the conversion layers produced are colorless and translucent, so that the treated metal surfaces appear metallic bright. Known methods for producing chromium-free colored conversion layers on metals include the addition of organic dyes, such as alizarin (WO 00/26437), fluorescent organic compounds, such as stilbene or coumarin derivatives (US 5,516,696) or transition metal compounds of, for example, molybdenum (WO 94/25640 ).

WO 2005/1 16294, on the other hand, discloses a conversion treatment agent which takes place in the presence of an organic polymer which, on the one hand, enhances the anticorrosive effect and the lacquer adhesion of the conversion layer and, on the other hand, carries the coloring substituent, so that the presence of this polymer on the metal surface can be recognized by the naked eye. The luminescent marker substituents are selected from Tuloidin Blue and from Neutral Red. The advantage of such a treatment agent is that the luminescent so causing the color impression Marker molecule is firmly bound to the polymer backbone. The luminescence is thus clearly attributable to the presence of a conversion layer, so that, if appropriate, it is also possible to deduce the layer thickness of the conversion coating.

In the aforementioned method, it has the disadvantage that conversion layers in the sense of organic-inorganic hybrid layers whose polymer content falls below a certain proportion in the conversion layer can no longer be perceived by the human eye as such because of the significantly reduced luminescence. In principle, however, the derivatization of the film-forming polymers with chromophoric or luminescent marker molecules is synthetically complicated and cost-intensive, in particular when high polymer fractions in the conversion layer are to be realized in the dry-in-place process.

Recently it has been shown that it is advantageous to use particulate inorganic pigments as an additional component in a conversion treatment. Such pigments, insofar as these are also present as nanoscale particles, give the conversion layer as well as the polymer constituents improved lacquer adhesion and corrosion resistance. For example, DE 10161383 discloses particulate inorganic systems selected from compounds of aluminum, barium, cerium, calcium, lanthanum, silicon, titanium, yttrium, zinc or zirconium having an average particle size of 6 to 150 nm as a further constituent of a corrosion-protecting treatment agent for layer formation in the "dry-in-place" method is applied.

The object of the present invention is therefore to provide chromium-free compositions and processes for the anticorrosive treatment of metal surfaces, wherein coating coatings with high corrosion resistance and good paint adhesion, which luminesce upon irradiation with ultraviolet light, are produced in a single step. In addition, the ratio of organic to inorganic content of the anticorrosion coating layer should be variably adjustable over a wide range and the intensity of the luminescence thereof should be largely independent.

This object is achieved by a chromium-free aqueous agent for the corrosion-protective treatment of metallic surfaces containing at least one particulate inorganic pigment, characterized in that the particulate inorganic pigment in the case of Luminescent with ultraviolet light and the pH of the agent is not greater than 4 and not less than 1.

By definition, the treatment solution is free of chromium, i. contains no intentionally added chromium compounds. However, traces of chromium can not be excluded as impurities, for example, as a result of leaching out of container material.

By "luminescence" the skilled person generally understands the radiative relaxation from electronically excited atomic, molecular and / or solid state states with the emission of light quanta. [Erfind L] Luminescence types preferred according to the invention are the fluorescence and / or phosphorescence caused by irradiation with ultraviolet light. The ultraviolet light typically used in the present invention for electronically exciting the particulate inorganic pigment should not be shorter than 200 nm, preferably not shorter than 280 nm, and most preferably not shorter than 320 nm. ultraviolet light ") is about 400 nm, but may also extend into the visible region of the light.

The inorganic luminescent pigments which can be used according to the invention comprise a "host material" and at least one doping element. A "host material" is defined according to the invention as a material whose elements are partly replaced by small amounts of so-called doping elements. Doping elements are different from the elements forming the host material.

The particulate inorganic pigments used according to the invention are at least partially crystalline or have crystalline regions in which the lattice elements (for example atoms or ions) are arranged spatially in regularly repeating unit cells to form a three-dimensional lattice. These crystalline domains within the inorganic pigment particles to be used according to the invention represent the crystalline skeleton hereinafter referred to as "host lattice." The doping of such a host lattice with suitable foreign atoms causes the luminescence upon irradiation with light of suitable wavelength, the individual impurity atoms initially receiving light energy change into an excited electronic atomic state, then under emission of a light quantum of lesser energy to relax back into the electronic ground state.

It is preferred according to the invention if the host material of the luminescence pigment is selected from oxides, sulfides or oxide sulfides of a metal or a semimetal. In this case, it is again preferable to select the metal or the semimetal from at least one member of the group which is formed from aluminum (preferably Al ³⁺ ), germanium (preferably Ge ⁴⁺ ), silicon (preferably Si ⁴⁺ ), scandium (preferably Sc ³⁺ ), yttrium (preferably Y ³⁺ ), lanthanum (preferably La ³⁺ ), cerium (preferably Ce ³⁺ ), praseodymium (preferably Pr ³⁺ ), neodymium (preferably Nd ³⁺ ), samarium (preferred Sm ³⁺ ), europium (preferably Eu ³⁺ ), gadolinium (preferably Gd ³⁺ ), terbium (preferably Tb ³⁺ ), dysprosium (preferably Dy ³⁺ ), holmium (preferably Ho ³⁺ ), erbium (preferably Er ^{3 +} ), Thulium (preferably Tm ³⁺ ), ytterbium (preferably Yb ³ +) or lutetium (preferably Lu ³⁺ ).

In particular, host lattices which are derived from the lattice structures of the perovskite, such as, for example, Mg ₂ GeO ₆ , BaMgAl ₁₀ Oi ₇ , CeMgAl ₁₀ Oi ₉ and Y ₂ O ₃ , and the analogous sulfidic or mixed oxidic-sulfidic host lattices are preferred.

The host material is preferably doped with doping elements selected from at least one metal cation of a metal of the transition metals of the 3rd and 4th period or of the rare earth metals (lanthanides). It is of course according to the definition of a doping element that the metal chosen as the doping element is different from the metal of the host material. In this case, it is again preferred if the doping element is selected from at least one metal cation of Mn ²⁺ , Mn ⁴⁺ , Ce ³⁺ , Pr ³⁺ , Nd ³⁺ , Sm ³⁺ , Eu ²⁺ , Eu ³⁺ , Gd ³⁺ , Tb ³⁺ , Dy ³⁺ , Ho ³⁺ , Er ³⁺ , Tm ³⁺ , Yb ³⁺ or Lu ³⁺ .

In the context of this invention, particular preference is given to doped host materials in the form of particulate inorganic pigments which luminesce upon irradiation with ultraviolet light in the visible range of the light, and in particular those which are recognizable to the human eye with sufficient intensity to luminesce. neszierenden properties of the pigment itself and not the agent or concentrate according to the invention are to be evaluated. In the context of the present invention, the size of the "primary particles" is taken as the basis for the classification of the particle or particle size. "Primary particles" are particles which are held together due to primary ionic or covalent forces, for example in the form of a crystal lattice In contrast to the primary particles, "secondary particles" are understood to be agglomerates of two or more primary particles which adhere to one another due to weak ionic or other polarity-based forces on the outer surfaces or grain boundaries of the primary particles and require little energy, for example a simple mechanical one Dispersion and / or by adding a dispersant which causes the splitting of the particles by eliminating or reducing the weak binding forces between the primary particles.

For the inventive use of the particulate inorganic luminescent pigments as marker material with good paint adhesion and corrosion protection properties, effective incorporation or generally good film-forming properties of these particles are a prerequisite. Therefore, in the agent or concentrate on which the invention is based, preferably at least 1 per cent, preferably at least 10 per cent, of inorganic pigment particles which have a particle size of not more than 2 μm, preferably not more than 0.2 μm and more preferably not have more than 0.02 microns.

For the determination of the size distribution of the pigment particles according to the invention, basically all particle measuring methods are suitable, preferably measuring methods based on the principle of light diffraction. The particle size data given in the context of the present invention relate to measurements with the MASTERSIZER X instrument, by Malvern Instruments, Herrsching, Germany, (version 1.2b). The operation of this apparatus is based on the diffraction of a light beam by the particle size is associated with the diffraction angle. The measurement of the light diffraction is possible directly and at any time in the agent or concentrate according to the invention.

Further methods for determining particle sizes are, for example, granulometry, in which a uniform slurry of a small amount of the powder to be investigated is prepared in a suitable dispersion medium and then exposed to sedimentation. Of course, the dispersed O

The means or concentrate according to the invention are used for such a sedimentation analysis for particle size determination. From the relationship between size and density of the particles assumed to be spherical and their sinking rate according to the Stokes law, it is possible to deduce the percentage distribution of the particle sizes over the time course of the sedimentation. The method of ultracentrifugation, in which sedimentation can be carried out at up to 10 ⁵ times the gravitational force, also makes it possible to determine particle size distributions of nanoscale dispersions. Further methods for determining the particle size are microscopy, electron microscopy, sieve analysis, determination of the density of the surface and the like.

Since the agent or concentrate according to the invention is present either mainly as a suspension or mainly as a dispersion of the inorganic pigment, a timely determination of the particle size distribution immediately after the formulation of the agent or concentrate is meaningful. Sedimentation and / or agglomeration processes define the stability of such suspensions or dispersions, so that there are defined maximum service lives or processing times for the particular agent or concentrate according to the invention. A control of the aforementioned preferred particle size distribution of the particulate inorganic luminescence pigment in the composition or concentrate via a continuous measuring method is therefore necessary for an optimal solution of the object underlying this invention. Thus, at least 50% by weight of the pigment fraction initially used should always be suspended and / or dispersed in the composition or concentrate according to the invention, where at least 1 per hundred, preferably at least 10 per cent, of the inorganic pigment particles present have a particle size of not more than 2 μm, preferably not more than 0.2 μm and more preferably not more than 0.02 μm.

The percentage number fraction of pigment particles up to a defined particle size in the dispersion and / or suspension is calculated as follows from the experimentally determined particle size distribution N (D):

with D _max the upper limit for the particle diameter for which the number fraction of particles is to be determined, which is below and equal to this diameter D _max .

The proportion of particulate inorganic pigments which luminesce upon irradiation with ultraviolet light is in the composition according to the invention, which at the same time represents an application solution, in particular for immersion methods, so-called "rinse" methods, preferably at least 0.05 g / l, more preferably 0.5 g / l, and is preferably not larger than 10 g / l.

The particulate inorganic pigments present in the composition according to the invention are deposited from the aqueous phase at the predetermined pH of not more than 4 and at least 1 on the metallic surface by contacting with the agent in a layer-forming manner. This happens due to the destabilization and agglomeration of the primary particles in close proximity to the metal surface. This layer-forming destabilization of the dispersed pigment particles is in turn caused by an increase in the pH at the metal surface caused by a corrosive stain of the metallic substrate. The increase in pH may extend several micrometers (10 ^"4 cm) into the interior of the treatment solution.

The corrosion resistance and stability of this coating can now be significantly improved by adding to the agent according to the invention fluorocomplexes of the elements titanium, zirconium, hafnium, silicon, aluminum, germanium, tin or boron, the conversion of the metal surface into an inorganic the respective cations of Cause fluorocomplexes contained layer, so that while the luminescent pigment is anchored more effectively with the metal surface.

The agent according to the invention, which at the same time represents an application solution, in particular for immersion processes, so-called "rinse" processes, preferably contains a total of at least 0.01 g / l, preferably at least 0.025 g / l, and up to 2 g / l, preferably up to 1 g / l, in particular up to 0.5 g / l of the elements titanium, zirconium, hafnium, silicon, aluminum, germanium, tin or boron and at least 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 from 1: 1 to 1: 6. The said Ti, Zr and / or Si ions may be completely in the form of hexafluorocomplexes such as, for example, the hexafluoroacids or their water-soluble in the concentration range mentioned Salts such as the sodium salts are used, in this case the atomic ratio is 1: 6. However, it is also possible to use complex compounds in which in each case less than six fluoride ions 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 this. As such further compounds are, for example, nitrates, carbonates, hydroxides and / or oxides thereof or another of the three mentioned central elements into consideration.

In a further aspect of the present invention, the agent according to the invention for more effective bonding of the luminescent pigments and increasing the paint adhesion of the otherwise purely inorganic corrosion-protective coating can also contain water-dispersible and / or water-soluble polymers or a polymer mixture with likewise layer-forming properties. In this case, the result of the treatment with a polymer-containing aqueous agent is the formation of an organic-inorganic layer coating on the metal surface. The respective organic or inorganic portion of the layer can be adjusted variably on the one hand on the composition of the composition according to the invention and on the other hand on the application method in a wide range.

For this purpose, the water-dispersible and / or water-soluble polymer or polymer mixture can consist of different groups, inter alia, epoxy resins, amino resins, phenol-aldehyde resins, polymers carrying carboxylic acid groups, polymeric alcohols, esterification products of polymeric alcohols with polymers carrying carboxylic acid groups, polymers carrying amino groups, homopolymers. or copolymers of vinylpyrrolidone and of polymers having phosphinic, phosphonic or phosphoric ester groups.

The phenol-aldehyde resins used are, in particular, amino-substituted poly (vinylphenol) compounds which are obtainable as Mannich adducts of poly (vinylphenols) with aldehydes and organic hydroxyl-containing amines. Examples of such poly-4-vinylphenol compounds can be found in WO 00/26437 and in the literature cited therein, in particular US Pat. No. 5,281,282. Further preferred water-soluble and / or water-dispersible organic polymers are selected from:

a) polyvinyl alcohol or water-soluble or water-dispersible partial esters thereof, b) polymers or copolymers of unsaturated mono- or dicarboxylic acids or their amides, c) esters of the polymers of groups a) and b), d) polymers or copolymers of vinylpyrrolidone, e) polymers of the diglycidyl ether of bisphenol A, f) copolymers of alkylenephosphonic or alkylenephosphinic acids and one or more unsaturated carboxylic acids.

In the case of the polymer of group a), a "partial ester" is understood to mean that only a part of the alcohol groups is esterified, the ester formation taking place with non-polymeric carboxylic acids. In particular, the ester formation can be carried out with monobasic carboxylic acids having 1 to 4 carbon atoms.

The polymers or copolymers of group b) may be selected, for example, from homopolymers or copolymers of acrylic acid and / or methacrylic acid whose acid groups may be partially replaced by amide groups or esterified with alcohols, 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 Glycerinpropo- xitriacrylat. These specific examples are known, for example, from WO 95/141 17. The polymers of group b) can furthermore be selected from those which contain maleic acid monomers. A specific example of this is a maleic acid-methyl vinyl ether copolymer.

Polymers of group a) generally contain free alcohol groups, those of group b) free carboxylic acid groups. Therefore, one can use these two polymers not only in a mixture with each other, but in a form in which between the alcohol groups of the polymer a) and the carboxylic acid groups of the polymer b) at least partially a Esterbil- occurred. This is explained in more detail in WO 94/12570. The teaching described therein can also be used in the context of the present invention.

Furthermore, the treatment solution may contain polymers of group d). Such polymers and their use in treatment solutions for the conversion treatment are described in more detail in DE-A-100 05 1 13 and DE-A-101 31 723.

Furthermore, the additional polymers can be selected from those of group e), as described in more detail in US Pat. No. 5,356,490.

The average molecular weight of the organic polymers is preferably at least 10,000 daltons. The upper limit of the molecular weight is not critical as long as the polymer is soluble or dispersible in the preferably acidic treatment solution in the desired concentration range. For example, the upper limit of the molecular weight may be 50,000,000, especially 20,000,000, and more preferably 10,000,000 daltons. An upper limit of 5,000,000 daltons may be sufficient. The average molecular weight is preferably greater than 50,000 daltons and in particular greater than 100,000 daltons. The average molar masses can be determined, for example, by gel permeation chromatography using a polyethylene glycol standard.

The proportion of water-dispersible and / or water-soluble polymers or of the polymer mixture in the composition according to the invention, which at the same time represents an application solution, in particular for immersion processes, so-called "rinse" processes, is preferably at least 1 ppm, particularly preferably 50 ppm and is preferably at most 1000 ppm.

The pH of the composition according to the invention should not be significantly lower than 1, since lower pH values lead to an increasingly stronger pickling attack on the metal surface. Preferably, the pH is not less than 2 and especially not less than 2.5. At pH values above 6, the formation of a conversion layer and / or the layer-forming deposition of the inorganic luminescent particles is no longer to the desired extent. Preferably, one works at pH values not higher than 4 and in particular not higher than 3.5. As optional components, various auxiliaries or additives may be present in the composition according to the invention which further improve the corrosion resistance and / or paint adhesion of the coating resulting from the treatment with the agent according to the invention.

These include acid-stable particulate inorganic pigments which do not luminesce in the visible range of light, preferably silicates and particularly preferably SiC> ₂ , the proportion of acid-stable particulate inorganic pigments being at least 0.05 g / l and at most 10 g / l.

Further inorganic compounds in particulate form which can be added to the composition according to the invention are carbonates, oxides, a silicate or a sulphate, in particular colloidal or amorphous particles based on at least one compound of aluminum, barium, cerium, calcium, lanthanum, silicon, titanium , Yttrium, zinc or / and zirconium particularly preferred, in particular particles based on alumina, barium sulfate, ceria, rare earth, oxide, silica, silicate, titanium oxide, yttria, zinc oxide or zirconia.

Preferably, the acid-stable particulate inorganic pigment which does not luminesce upon irradiation with ultraviolet light has a particle size distribution such that at least 1 of hundreds, preferably at least 10, of the acid-stable inorganic pigment particle has a particle size of not more than 2 μm, preferably not more more than 0.2 .mu.m, and more preferably not more than 0.02 .mu.m. In the event that substrates treated or coated according to the invention, in particular those with a high polymer content in the layer coating, wherein the layer thicknesses are greater than 1 micron, should be welded, it may be advantageous as inorganic pigment compounds in particle form with higher or higher 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 such as molybdenum sulfide, graphite or / and carbon black, these particles then also have such an average particle size can, that they possibly protrude somewhat stronger from the layer produced according to the invention. Furthermore, the agent according to the invention may additionally contain cations of copper and / or oxoanions of molybdenum, tungsten and / or vanadium in a proportion of at least 5 ppm and at most 200 ppm.

Oxoanions of phosphorus, preferably phosphate anions, may also be present in the composition according to the invention with a proportion of the oxoanions, based on the element phosphorus, of at least 0.5 g / l and at most 20 g / l.

In order to increase the pickling rate, in particular in the surfaces to be treated, which consist at least partially of aluminum, and thus accelerate the deposition of a conversion layer and / or the inorganic, may be additionally contained in the inventive agent fluoride ions, wherein the proportion of fluoride Ions is at least 0.05 g / l and at most 5 g / l.

"Accelerators" known to those skilled in the field of corrosion-protective phosphation, which effect an increased pickling attack on the metallic substrate, can also be used for the deposition of homogeneous, closed film coatings.

0.3 to 4 g / l chlorate ions,

0.01 to 0.2 g / l nitrite ion, 0.05 to 4 g / l nitroguanidine, 0.05 to 4 g / l N-methylmorpholine N-oxide, 0.2 to 2 g / l m-nitrobenzenesulfonate from 0.05 to 2 g / l of m-nitrobenzoate ions, from 0.05 to 2 g / l of p-nitrophenol,

1 to 150 mg / l of hydrogen peroxide in free or bound form, 0.1 to 10 g / l of hydroxylamine in free or bound form, 0.1 to 10 g / l of reducing sugars

A further aspect of this invention is also the provision of concentrates which, when appropriately diluted, give the composition according to the invention or as a concentrated aqueous composition directly for use, ie for the treatment of the metallic Surface, can be used. The direct use of such concentrates according to the invention is particularly suitable for so-called "no-rinse" processes in which a defined liquid film is applied to the metal substrate (eg via roller application or spray application with squeezing) and then dried to form a layer "Concentrate a high proportion of water-soluble and / or water-dispersed polymers which form a homogeneous closed film coating at a suitable specific temperature (" film forming temperature ").

The present invention therefore comprises an aqueous concentrate for the anticorrosive treatment of metallic surfaces, characterized in that by dilution with water by a factor of at least 10 and at most 200 the agent according to the invention results according to the preferred compositions described above.

Preferably a concentrate which, when diluted by a factor of at least 10 and at most 200, either contains the agent according to the invention: a) fluorocomplexes of the elements titanium, zirconium, hafnium, silicon, aluminum, germanium, tin or boron with a total content of at least 0, 01 g / l, preferably at least 0.025 g / l, and up to 2 g / l, preferably up to 1 g / l, in particular up to 0.5 g / l; b) at least one water-dispersible and / or water-soluble polymer having a proportion of at least 1 ppm, particularly preferably 50 ppm and preferably at most 1000 ppm; or c) both a) and b), wherein the particulate inorganic pigments which luminesce upon irradiation with ultraviolet light, in the concentrate in a proportion of at least 0.05 g / l, more preferably of 0.5 g / l and preferably are not larger than 10 g / l.

The invention likewise encompasses a concentrate which, when diluted by a factor of at least 10 and not more than 200, either contains the agent according to the invention comprising: a) the particulate inorganic pigments which luminesce when irradiated with ultraviolet light, in a proportion of at least 0.05 g / 1, particularly preferably 0.5 g / l and preferably not more than 10 g / l; b) at least one water-dispersible and / or water-soluble polymer having a proportion of at least 1 ppm, particularly preferably 50 ppm and preferably at most 1000 ppm; or c) both a) and b), wherein the fluorocomplexes of the elements titanium, zirconium, hafnium, silicon, aluminum, germanium, tin or boron in a proportion of at least 0.01 g / l, preferably at least 0.025 g / l , and up to 2 g / l, preferably up to 1 g / l, in particular up to 0.5 g / l are included.

In addition, the invention comprises a concentrate which, when diluted by a factor of at least 10 and at most 200, contains the agent according to the invention comprising: a) the particulate inorganic pigments which luminesce upon irradiation with ultraviolet light, in a proportion of at least 0.05 g / l , more preferably 0.5 g / l, and preferably not greater than 10 g / l; b) at least one water-dispersible and / or water-soluble polymer having a proportion of at least 1 ppm, particularly preferably 50 ppm and preferably at most 1000 ppm; and c) the fluorocomplexes of the elements titanium, zirconium, hafnium, silicon, aluminum, germanium, tin or boron in a proportion of at least 0.01 g / l, preferably at least 0.025 g / l, and up to 2 g / l, preferably up to 1 g / l, in particular up to 0.5 g / l, wherein one or more of the above-described optional components are contained in the respective preferred amounts in the concentrate.

In addition, the concentrate of the invention contains largely no chromium compounds and the content of chromium compounds based on the element chromium is preferably less than 100 ppm.

Furthermore, the pH of the concentrate according to the invention is such that when diluted by a factor of at least 10 and at most 200, a pH of not greater than 4 and not less than 1 results. The pH of the concentrate may therefore also be below 1, but should not be less than 0.3.

The method according to the invention comprises treating a metallic surface with such a means and visually assessing the quality of the treatment process on the basis of a luminescence of the metal surface which is as homogeneous as possible, caused by the inorganic pigment according to the invention immobilized in the protective layer against corrosion of the metallic substrate and / or superficially immobilized , And therefrom derived further process steps to optimize the treatment process and / or the layer quality.

The present invention therefore also encompasses a metal substrate treated according to one or more of the methods described herein ("rinse" / "no-rinse" method), wherein the substrate thus treated luminesces upon irradiation with ultraviolet light, and preferably luminescence in the visible region of the light is visible to the human eye.

Such a treated or coated metal substrate can be used in the body shop in automotive manufacturing, shipbuilding, construction and for the production of white goods.

The metal surfaces that can be treated with the agent, concentrate and method of the invention are preferably selected from zinc and zinc alloy surfaces, galvanized or alloy galvanized steel, aluminum and aluminum alloys, magnesium and magnesium alloys, titanium and titanium alloys. 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 steels such as Galvalume or Galfan, which carry a coating of zinc / aluminum alloys.

Claims

oPatentansprüche

1. Aqueous agent for the corrosion-protective treatment of metallic surfaces containing at least one particulate inorganic pigment, characterized in that the particulate inorganic pigment luminesces when irradiated with ultraviolet light and the pH of the agent is not greater than 4 and not less than 1.

2. Composition according to claim 1, characterized in that in addition at least one or more fluorine complexes of the elements titanium, zirconium, hafnium, silicon, aluminum, germanium, tin or boron are included.

3. Composition according to claim 1, characterized in that additionally at least one or more water-dispersible and / or water-soluble polymers are contained.

4. Composition according to one or more of the preceding claims, characterized in that both at least one or more fluorocomplexes of the elements titanium, zirconium, hafnium, silicon, aluminum, germanium, tin or boron and at least one or more water-dispersible and / or water-soluble polymers are included.

5. Composition according to claim one or more of the preceding claims, characterized in that the particulate pigment represents an inorganic compound of the type of a host lattice doped with one or more cations of the transition metals of the 3rd and 4th period or of the rare earth metals.

6. Composition according to claim 5, characterized in that the host lattice of the particulate inorganic pigment is an oxide.

7. Composition according to one or more of the preceding claims, characterized in that the particulate inorganic pigment recognizably luminesces in the visible range of the light to the human eye.

8. Composition according to one or more of the preceding claims, characterized in that at least 1 of a hundred, preferably at least 10 per cent of the inorganic pigment particles contained a particle size of not more than 2 microns, preferably not more than 0.2 microns and especially preferably not more than 0.02 microns own.

9. Composition according to one or more of claims 3 to 8, characterized in that as water-dispersible and / or water-soluble polymer one or more Mannich adducts of poly (vinylphenols) with aldehydes and organic hydroxyl-containing amines are used.

10. Composition according to one or more of claims 3 to 9, characterized in that the water-dispersible and / or water-soluble polymer is selected from polyvinyl alcohol, polymers of bisphenol A diglycidyl ether and / or polymers and copolymers of acrylic acid, methacrylic acid and maleic acid and their esters or amides.

1 1. Composition according to one or more of claims 3 to 10, characterized in that the proportion of water-dispersible and / or water-soluble polymers is at least 1 ppm and at most 1000 ppm.

12. Composition according to one or more of the preceding claims, characterized in that the proportion of particulate inorganic pigments which luminesce upon irradiation with ultraviolet light, at least 0.05 g / l and at most 10 g / l.

13. Composition according to one or more of claims 2 and 4 to 1 1, characterized in that the proportion of fluoro complexes of the elements titanium, zirconium, hafnium, silicon, aluminum, germanium, tin or boron at least 0.01 g / l and at most 2 g / l.

14. Composition according to one or more of the preceding claims, characterized in that in addition one or more acid-stable particulate inorganic pigments are included, which do not luminesce in the visible range of light, preferably silicates and more preferably SiC> ₂ , said proportion of acid-stable particulate inorganic pigments is at least 0.05 g / l and at most 10 g / l.

15. Composition according to one or more of the preceding claims, characterized in that in addition cations of copper and / or oxoanions of molybdenum, tungsten and / or vanadium are present in a proportion of at least 5 ppm and at most 200 ppm.

16. Composition according to one or more of the preceding claims, characterized in that in addition oxoanions of phosphorus, preferably phosphate anions are contained, wherein the proportion of oxoanions based on the element phosphorus at least 0.5 g / l and at most 20 g / l is.

17. Composition according to one or more of the preceding claims, characterized in that in addition fluoride ions are contained, wherein the proportion of fluoride ions is at least 0.05 g / l and at most 5 g / l.

18. Composition according to one or more of the preceding claims, characterized in that in addition accelerators selected from nitroguanidine, N-methylmorpholine-N-oxide, m-nitrobenzenesulfonate ions, m-nitrobenzoate ions, p-nitrophenol, hydroxylamine, hydrogen peroxide, nitrite And / or reducing sugars are included.

19. Composition according to one or more of the preceding claims, characterized in that substantially no chromium compounds are contained and the content of chromium compounds based on the element chromium is preferably less than 100 ppm.

20. Aqueous concentrate for the corrosion-protective treatment of metallic surfaces, characterized in that by dilution with water by a factor of min. at least 10 and at most 200 the agent according to one or more of claims 2 to 18 results.

21. Concentrate according to claim 20, characterized in that the particulate inorganic pigments which luminesce upon irradiation with ultraviolet light, according to claim 12 in the concentrate.

22. Concentrate according to one or both of Claims 20 and 21, characterized in that the fluorocomplexes of the elements titanium, zirconium, hafnium, silicon, aluminum, germanium, tin or boron according to Claim 13 are contained in the concentrate.

23. Concentrate according to one or more of claims 20 to 22, characterized in that one or more of the components according to claims 14 to 18 are contained in the concentrate.

24. Concentrate according to one or more of claims 20 to 23, characterized in that substantially no chromium compounds are contained and the content of chromium compounds based on the element chromium preferably less than

100 ppm.

25. Concentrate according to one or more of claims 21 to 24, characterized in that the pH is not greater than 4 and not less than 0.3.

26. A process for the corrosion-protective treatment of metallic surfaces, wherein the cleaned metallic surface is brought into contact with the agent or the concentrate according to one or more of the preceding claims.

27. The method according to claim 26, characterized in that after contacting the cleaned metallic surface with an agent or concentrate according to one or more of claims 1 to 25 adhering to the metallic surface aqueous film is dried, wherein a layer thickness of the drying formed layer of not more than 5 microns, preferably not more than 1 micron, but resulting in at least 0.02 microns.

28. The method according to claim 26, characterized in that immediately after contacting the cleaned metallic surface with an agent according to one or more of claims 1 to 19 and without intervening drying step further rinsing, aftertreatment and / or coating steps follow.

29. The method according to claim 27, characterized in that further rinsing, aftertreatment and / or coating steps follow.

30. The method according to claim 26 or 27, characterized in that the thus treated metallic surfaces are irradiated with or without intervening rinsing step first with ultraviolet light, wherein an optical assessment of the entire treated metallic surface takes place with respect to a homogeneous luminescence, so that in case of inhomogeneous luminescence either:

(A) the process according to claim 26 or 27 is repeated until the entire treated metallic surface, when irradiated with ultraviolet light, has as homogeneous a luminescence as possible of the total treated metallic;

(B) the areas of the treated metallic surface which have no or a relative to the entire surface as too low valued luminescence, locally treated according to the method of claim 26 or 27 and this often to a homogeneous as possible luminescence of the entire treated metallic surface under irradiation with ultraviolet light results;

(C) at least one parameter which effects the cleaning of the metallic surface is adapted such that the treatment of further metallic surfaces according to claim 26 or 27 results in the most homogeneous possible luminescence of the entire treated metallic surface;

(D) the proportion of at least one of the components of the agent or concentrate according to one or more of claims 1 to 25 is increased such that the treatment of other metallic surfaces according to claim 26 or 27 in a As homogeneous as possible luminescence of the entire treated metallic surface results, without causing a specified in claims 1 to 25 predetermined amount of a component is exceeded or fallen below; or

(E) in a subsequent step, a post passivation of the entire metallic surface takes place.

31. The method according to claim 30, characterized in that both the optical assessment of the luminescence as well as the derived therefrom process steps (A-E) take place automatically without human intervention.

32. Metal substrate treated according to one or more of claims 26 to 31, characterized in that the thus treated substrate luminesces upon irradiation with ultraviolet light.

33. Metal substrate according to claim 32, characterized in that the luminescence in the visible range of the light is visible to the human eye.

34. Use of a metal substrate according to claim 32 or 33 in the bodywork in automotive manufacturing, shipbuilding, construction and for the production of white goods.