Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/82—After-treatment
  • C23C22/83—Chemical after-treatment
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
  • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
  • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2222/00—Aspects relating to chemical surface treatment of metallic material by reaction of the surface with a reactive medium
  • C23C2222/10—Use of solutions containing trivalent chromium but free of hexavalent chromium

Definitions

• the invention relates to the corrosion protection of metallic materials, in particular of those which are provided with a conversion layer.
• the coating of the metallic workpiece to be protected with a coating of another metal is a widely used and established method in the art.
• the coating metal can behave in the corrosive medium either electrochemically nobler or less noble than the material base metal. If the coating metal behaves less noble, it acts in the corrosive medium compared to the base metal as a sacrificial anode (cathodic corrosion protection).
• this protective function associated with the formation of corrosion products of the coating metal is thus desired, the corrosion products of the coating often lead to undesirable decorative and often also to functional impairments of the workpiece.
• cathodically protective base coating metals such as, for example, Zinc or aluminum and their alloys often used so-called conversion coatings.
• conversion coatings These are reaction products of the non-noble coating metal which are insoluble in aqueous media over a wide pH range with the treatment solution. Examples of these so-called conversion layers are so-called phosphating and chromating.
• the layer to be protected is immersed in an acidic solution containing phosphate ions (see, for example, US Pat WO 00/47799 ).
• the acidic medium leads to the partial dissolution of zinc from the coating.
• the liberated Zn 2+ cations form a sparingly soluble zinc phosphate layer on the surface with the phosphate ions of the treatment solution. Since zinc phosphate layers themselves form only a comparatively bad corrosion protection, but an excellent primer for For this applied paints and paints, their main application is in the function of a primer for coatings and paints.
• chromium (VI) ions see EP 0 553 164 A1 .
• chromium (VI) is reduced to chromium (III), which in the surface film which is more alkaline by the evolution of hydrogen, inter alia as chromium (III) hydroxide or as sparingly soluble ⁇ -oxo or ⁇ -hydroxo bridged chromium (III) Complex is deposited.
• chromium (III) hydroxide inter alia as chromium (III) hydroxide or as sparingly soluble ⁇ -oxo or ⁇ -hydroxo bridged chromium (III) Complex is deposited.
• sparingly soluble zinc chromate (VI) is formed. Overall, a tightly closed, very well protects against corrosion attack by electrolytes conversion coating on the zinc surface.
• chromium (VI) compounds are acutely toxic and highly carcinogenic, requiring replacement of the methods associated with these compounds.
• a disadvantage of this additional process step using polymer dispersions is the occurrence of drainage drops in the coating of workpieces produced on the frame and / or the bonding of coated bulk material;
• problems such as dimensional accuracy of threads and the like are associated with the layer thickness of these organic sealants. If such sealings have a high degree of corrosion protection, the adhesion to the coated substrate is generally very good. This also means a very good adhesion to machine parts of the coating equipment, what their Cleaning difficult. Goods with coating defects, which should again go through the entire coating process, also has to be stripped of costs again, which usually requires an additional process step.
• the object of the invention is to provide processes for increasing the corrosion protection of metallic, in particular zinc-containing, surfaces provided with conversion layers.
• the aim is to preserve or improve the decorative and functional properties of the surfaces.
• the above-mentioned problems in the use of chromium (VI) -containing compounds or post-treatments with polymer dispersions should be avoided.
• the invention provides a method for producing a corrosion-protective coating layer, wherein a surface to be treated is contacted with an aqueous treatment solution containing chromium (III) ions and at least one phosphate compound, wherein the ratio of molar concentration (ie the concentration in mol / l) of chromium (III) ions to the molar concentration of the at least one phosphate compound (calculated based on orthophosphate) ([chromium (III) ions]: [phosphate compound]) between 1: 1.5 and 1: 3 lies.
• Phosphate compounds are derived from phosphorus in the oxidation state + V derived oxo compounds and their esters with organic radicals having up to 12 carbon atoms and the salts of mono- and diesters.
• Suitable phosphate compounds are in particular alkyl phosphates with alkyl groups having up to 12 carbon atoms.
• Suitable phosphate compounds are ortho-phosphoric acid (H 3 PO 4 ) and its salts, polyphosphoric acid and its salts, meta-phosphoric acid and its salts, Phosphoric acid methyl esters (mono-, di- and triesters), phosphoric acid ethyl esters (mono-, di- and triesters), phosphoric acid n- propyl esters (mono-, di- and triesters), phosphoric acid isopropyl ester (mono-, di- and triesters), phosphoric acid n -butyl ester (mono-, di- and triester), phosphoric acid 2-butyl ester (mono-, di- and triester), phosphoric acid tert-butyl ester (mono-, di- and triester), the salts of the monosubstituted and diesters and di- phosphorus pentoxide and mixtures of these compounds.
• the term "salts" includes not only the salts of
• the treatment solution preferably contains between 0.2 g / l and 20 g / l of chromium (III) ions, more preferably between 0.5 g / l and 15 g / l of chromium (III) ions and more preferably between 1 g / 1 and 10 g / l of chromium (III) ions.
• the ratio of the molar concentration of chromium (III) ions to the molar concentration of the at least one phosphate compound (calculated on the basis of orthophosphate) is between 1: 1.5 and 1: 3, preferably between 1: 1.7 and 1: 2.5.
• Chromium (III) may be added to the treating solution either in the form of inorganic chromium (III) salts, e.g. basic chromium (III) sulfate, chromium (III) hydroxide, chromium (III) dihydrogen phosphate, chromium (III) chloride, chromium (III) nitrate, potassium chromium (III) sulfate or chromium (III) salts organic Acids such as Chromium (III) methanesulfonate, chromium (III) citrate may be added or produced by reduction of suitable chromium (VI) compounds in the presence of suitable reducing agents. Suitable chromium (VI) compounds are e.g.
• Chromium (VI) oxide Chromium (VI) oxide, chromates, such as potassium or sodium chromate, dichromates, e.g. Potassium or sodium dichromate.
• Suitable reducing agents for in situ generation of chromium (III) ions are e.g. Sulfites, e.g. Sodium sulfite, sulfur dioxide, phosphites, e.g. Sodium hypophosphite, phosphorous acid, hydrogen peroxide, methanol.
• the treatment solution preferably has a pH between pH 2.5 and pH 7, preferably between pH 3 and pH 6, and particularly preferably between pH 3.5 and pH 5.
• the treatment solution may additionally (optionally) contain one or more complexing agents.
• Suitable complexing agents are, in particular, organic chelate ligands.
• suitable complexing agents are polycarboxylic acids, hydroxycarboxylic acids, hydroxypolycarboxylic acids, aminocarboxylic acids or hydroxyphosphonic acids.
• suitable carboxylic acids are citric, tartaric, malic, lactic, gluconic, glucuronic, ascorbic, isocitric, gallic, glycolic, 3-hydroxypropionic, 4-hydroxybutyric, salicylic, nicotinic, alanine, glycine, asparagine, aspartic, cysteine, glutamic, glutamine , Lysine.
• Suitable hydroxyphosphonic acids are, for example, Dequest 2010 TM (from Solutia Inc.); suitable as aminophosphonic acids, for example Dequest 2000 TM (from Solutia Inc.).
• the treatment solution will contain at least one metal or metalloid, e.g. Sc, Y, Ti, Zr, Mo, W, Mn, Fe, Co, Ni, Zn, B, Al, Si, P.
• metal or metalloid e.g. Sc, Y, Ti, Zr, Mo, W, Mn, Fe, Co, Ni, Zn, B, Al, Si, P.
• These elements may be added in the form of their salts or in the form of complex anions or the corresponding acids of these anions such as hexafluoroboric acid, hexafluorosilicic acid, hexafluorotitanic acid or hexafluorozirconic acid, tetrafluoroboric acid or hexafluorophosphoric acid or their salts.
• zinc which may be added in the form of zinc (II) salts, for example zinc sulfate, zinc chloride, zinc phosphate, zinc oxide or zinc hydroxide.
• the treatment solution is added between 0.5 g / l and 25 g / l, more preferably between 1 g / l and 15 g / l Zn 2+ .
• the list of zinc compounds merely gives examples of compounds suitable according to the invention, but does not limit the amount of suitable zinc compounds to the substances mentioned.
• the treatment solution may additionally (optionally) contain one or more water-soluble or water-dispersible polymers selected from the group consisting of polyethylene glycols, polyvinylpyrrolidones, polyvinyl alcohols to improve the film formation on the surface to be treated and to increase the hydrophobicity of the surface.
• polyethylene glycols polyvinylpyrrolidones
• polyvinyl alcohols polyvinyl alcohols
• the concentration of the at least one polymer is preferably in the range between 50 mg / l and 20 g / l.
• the layer properties of the deposited corrosion protection layer are significantly improved.
• the treatment solution may additionally (optionally) contain one or more wetting agents.
• one or more wetting agents may additionally (optionally) contain one or more wetting agents.
• fluoroaliphatic polymeric esters such as Fluorad FC-4432 TM (from 3M).
• the surfaces treated according to the invention are metallic, preferably zinc-containing, surfaces provided with a chromium (III) -containing conversion layer.
• a layer is deposited on the treated surface comprising chromium, phosphate (s) and optionally a metal, e.g. Zinc, and optionally one or more polymeric components.
• the inventive method leads to untreated, that is freshly deposited, not provided with a conversion layer zinc or zinc alloy surfaces not significantly contributing to the corrosion protection layers.
• the contacting of the treatment solution with the surface to be treated can be carried out in the inventive method according to known methods, in particular by immersion.
• the temperature of the treatment solution is preferably between 10 ° C and 90 ° C, more preferably between 20 ° C and 80 ° C, more preferably between 40 ° C and 60 ° C.
• the duration of the contacting is preferably between 0.5 s and 180 s, more preferably between 5 s and 60 s, most preferably between 10 s and 30 s.
• the treatment solution can be prepared prior to carrying out the method according to the invention by dilution of a correspondingly higher concentrated concentrate solution.
• the objects treated according to the invention are no longer rinsed after being brought into contact, but dried.
• a treatment solution according to the invention was prepared which contained the following constituents: 7 g / l Cr 3+ from chromium (III) hydroxide 28 g / l PO 4 3- from ortho-phosphoric acid 9 g / l Zn 2+ from zinc oxide 18 g / l citric acid
• the pH of the solution was adjusted to pH 3.9 with 20% sodium hydroxide solution.
• test parts made of steel were coated in a weakly acidic process (Protolux 3000 TM from Atotech GmbH) with an 8-10 ⁇ m thick zinc coating and rinsed with demineralized water.
• a treatment solution according to the invention having the same composition as in Example 1 was prepared; the pH of the solution was adjusted to pH 3.9 with 20% sodium hydroxide solution.
• the test part used was a galvanized steel part, which was treated with a black passivation solution containing essentially Cr 3+ , NO 3 - , F - , and Fe 2+ (Tridur Zn H1 TM from Atotech GmbH) with a black Conversion layer has been provided.
• the sample part thus treated was rinsed after the black passivation and immersed without intermediate drying step for 20 s in the inventive, heated to 60 ° C treatment solution.
• the part was then dried without rinsing at 60-80 ° C for 5 minutes in a convection oven.
• the part thus treated had a black, slightly iridescent surface. There were clearly visible trace traces.
• the neutral salt spray test according to DIN 50021 SS showed no white corrosion for up to 48 h.
• Example 3 to 6 were carried out as Example 2 except that the composition of the treatment solution was varied as shown in Table 1. (In addition, the drying time in Examples 4 to 6 was 15 minutes each.) The appearance of the surface of the obtained sample parts and the corrosion properties are also shown in Table 1 (together with the data of Example 2). ⁇ b> Table 1.

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• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Treatment Of Metals (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

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• 2007
  • 2007-06-14 EP EP07011720.5A patent/EP2014793B1/fr active Active
  • 2007-06-14 ES ES07011720.5T patent/ES2444406T3/es active Active
• 2008
  • 2008-06-13 CN CN200880017265A patent/CN101720364A/zh active Pending
  • 2008-06-13 JP JP2010511544A patent/JP5266317B2/ja active Active
  • 2008-06-13 WO PCT/EP2008/004793 patent/WO2008151829A1/fr active Application Filing
  • 2008-06-13 US US12/664,002 patent/US8435360B2/en active Active
  • 2008-06-13 KR KR1020097027482A patent/KR20100038325A/ko not_active Application Discontinuation

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