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  Colored conversion layers on metallic substratesRelated Patent Categories: Metal Treatment, Process Of Modifying Or Maintaining Internal Physical Structure (i.e., Microstructure) Or Chemical Properties Of Metal, Process Of Reactive Coating Of Metal And Process Of Chemical-heat Removing (e.g., Flame-cutting, Etc.) Or Burning Of Metal, Processes Of Coating Utilizing A Reactive Composition Which Reacts With Metal Substrate Or Composition Therefore, Liquid Reactive Coating Composition Utilized, Dye Or Organic Pigment ContainingThe Patent Description & Claims data below is from USPTO Patent Application 20070095435. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE [0001] This application is a continuation under 35 USC Sections 365 (c) and 120 of International Application No. PCT/EP2005/000769, filed Jan. 27, 2005 and published Dec. 8, 2005 as WO 2005/116294 which claims priority to DE 10 2004 022 565.6 filed May 7, 2004, each of which is incorporated herein by reference in its entirety. FIELD OF THE INVENTION [0002] This invention relates generally to the chemical surface treatment of zinc or galvanized steel, aluminium, magnesium or alloys thereof and, more particularly, to chromium-free conversion processes for such metal surfaces, i.e. chemical treatment processes which lead to the formation of a surface layer in which both cations of the treated metal surface and ions from the treatment solution are incorporated. The chromium-free coating is colored so that it is possible to tell by simple visual inspection whether an adequate conversion layer has been formed. The function of this conversion layer is to reduce the tendency of the metal surface towards corrosion and to establish good adhesion between the metal surface and an organic coating applied to the conversion layer, for example in the form of a paint or an adhesive. DISCUSSION OF THE RELATED ART [0003] Extensive prior art exists on the production of chromium-free conversion layers on the metal surfaces mentioned. [0004] U.S. Pat. No. 5,129,967 discloses treatment baths for the no-rinse treatment (or "dried in place conversion coating") of aluminium which contain a) 10 to 16 g/l polyacrylic acid or homopolymers thereof, 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. [0005] EP-B-8 942 discloses treatment solutions, preferably for aluminium cans, containing a) 0.5 to 10 g/l polyacrylic acid or an ester thereof and b) 0.2 to 8 g/l of at least one of the compounds H.sub.2ZrF.sub.6. H.sub.2TiF.sub.6 and H.sub.2SiF.sub.6, the pH value of the solution being below 3.5. [0006] Other polymers which may be used in similar treatment baths are disclosed in WO 02/20652. [0007] U.S. Pat. No. 4,992,116 describes treatment baths for the conversion treatment of aluminium with pH values of about 2.5 to 5 which contain at least three components: [0008] a) phosphate ions in concentrations of 1.1.times.10.sup.-5 to 5.3.times.10.sup.-3 mol/l, corresponding to 1 to 500 mg/l, [0009] b) 1.1.times.10.sup.-5 to 1.3.times.10.sup.-3 mol/l of a fluoro acid of an element from the group consisting of Zr, Ti, Hf and Si (corresponding to 1.6 to 380 mg/l, depending on the element) and [0010] c) 0.26 to 20 g/l of a polyphenol compound obtainable by reaction of poly(vinylphenol) with aldehydes and organic amines. [0011] WO 92/07973 teaches a chromium-free treatment process for aluminium which uses 0.01 to about 18% by weight of H.sub.2ZrF.sub.6 and 0.01 to about 10% by weight of a 3-(N--C.sub.1-4-alkyl-N-2-hydroxyethylaminomethyl)-4-hydroxystyrene polymer as essential components in an acidic aqueous solution. Optional components are 0.05 to 10% by weight of dispersed SiO.sub.2, 0.06 to 0.6% by weight of a solubilizer for the polymer and surfactant. The polymer mentioned comes under the group of "reaction products of poly(vinylphenol) with aldehydes and organic amines containing hydroxyl groups" described in the following which suitable for use in accordance with the present invention. [0012] WO 00/71626 discloses a chromium-free corrosion-inhibiting composition containing water and [0013] a.) 0.5 to 100 g/l hexafluoro anions of titanium(IV), silicon(IV) and/or zirconium(IV) [0014] b.) 0 to 100 g/l phosphoric acid [0015] c.) 0 to 100 g/l of one or more compounds of cobalt, nickel, vanadium, iron, manganese, molybdenum or tungsten [0016] d.) 0.5 to 30% by weight of at least one water-soluble or water-dispersible film-forming organic polymer or copolymer (based on active substance) [0017] e.) 0.1 to 10% by weight of an organophosphonic acid [0018] f.) optionally other auxiliaries and additives. [0019] It is clear in many cases from the documents cited above that the conversion layers produced are colorless and transparent, so that the treated metal surfaces have a bright metallic appearance. At least it is not disclosed in those documents that colored layers would be formed. The lack of color in the prior art coatings is a drawback where, from many years' experience in the chromating of metal surfaces, the expert in this field is accustomed to obtaining a colored layer as the outcome of the conversion treatment. One is then immediately able to see whether the treatment has produced the desired result. In the production of colorless layers, however, this involves complicated surface analysis, for example determining the Ti or Zr content of the surface by X-ray fluorescence measurement. Accordingly, there is a need in practice for surface treatment processes which not only are comparable with conventional chromating layers in their properties in regard to corrosion prevention and paint adhesion, but are also visible to the human eye in the same way as chromating layers. [0020] Proposals for solving this problem exist in the prior art. For example, WO 94/256450 describes a process for producing blue-colored conversion layers on zinc/aluminium alloys. In this process, the metal surfaces are contacted with a treatment solution which has a pH of 3.5 to 6 and which contains 0.2 to 3.0% by weight molybdenum and 0.1 to 2.0% by weight fluoride. The molybdenum may be used as molybdate, as phosphomolybdic acid, as molybdenum chloride and the like. The fluoride may be used in the form of hydrofluoric acid, simple fluorides and complex fluoro acids, such as fluorotitanic acid or fluorozirconic acid for example. [0021] The teaching of WO 00/26437 goes the way of coloring the conversion layer with an organic dye (alizerin dye). The conversion layer itself is produced with a treatment solution containing complex fluorides, for example of titanium and zirconium, besides other inorganic oxides, hydroxides or carbonates or reaction products thereof with the fluoro acids. A poly-4-hydroxystyrene substituted by amino groups (polyvinyl phenol) may additionally be used as an organic polymer. [0022] FR 2 461 764 proposes the chemical oxidation of the aluminium surface with organic nitro compounds in alkaline solution. After the oxidation step, the layers may be colored with an organic dye. A similar two-step process is proposed in WO 01/71060. This document describes a multilayer coating of a conversion layer (obtainable, for example, electrochemically and having pores) applied to the metal and a colored layer on the conversion layer. The second colored layer may be obtained by contact with a solution containing at least one alkoxysilane compound and a dye, followed by polymerization and/or crosslinking of the alkoxysilane compound. [0023] The processes cited above for producing chromium-free colored conversion layers on metals, such as aluminium for example, may be divided into two groups. In the first group, transition metal compounds, such as molybdates or polymolybdates for example, or organic dyes are incorporated in the conversion layer. In the second group, a conversion layer is conventionally produced and the organic dyes are applied to the conversion layer already formed in a second step. There appears to be no example of a conversion treatment of metal surfaces carried out in the presence of an organic polymer which, on the one hand, improves the corrosion-inhibiting effect and paint adhesion of the conversion layer and which, on the other hand, carries color-bearing substituents, so that the presence of this polymer on the metal surface can be detected with the eye. [0024] In the treatment of circulating waters, for example of industrial cooling systems, it is known that organic polymers can be added to prevent corrosion or deposits. In this case, the problem arises of monitoring the concentration of these polymers in the circuit water. To this end, EP 504 520 proposes covalently bonding dye residues to the organic polymers used for this purpose, so that the concentration of the polymers in the circuit water can readily be determined by an absorption or fluorescence measurement. This document discloses a number of organic dye residues and monomers which can be reacted with one another and polymerized to obtain polymers containing color-bearing groups. For example, these polymers may contain one or more of the following monomers: acrylic acid, acrylamide, sulfomethacrylamide, vinyl acetate, methacrylic acid or acrylonitrile. Continue reading... Full patent description for Colored conversion layers on metallic substrates Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Colored conversion layers on metallic substrates patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. 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