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
  • C23C22/05—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
  • C23C22/34—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 fluorides or complex fluorides
• • 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
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
  • C25D11/18—After-treatment, e.g. pore-sealing
  • C25D11/24—Chemical after-treatment
  • C25D11/246—Chemical after-treatment for sealing layers
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D13/00—Electrophoretic coating characterised by the process
  • C25D13/20—Pretreatment

Definitions

• the present invention relates to a multistage process for the corrosion-protective and adhesion-promoting treatment of metal surfaces comprising a first process step for passivating pretreatment with an acidic aqueous composition (A) comprising water-soluble compounds of Zr and / or Ti and fluoride ions a subsequent process step for aftertreatment with an aqueous Composition (B) containing) at least one organic compound having at least one aromatic heterocycle, wherein the aromatic heterocycle has at least one nitrogen atom.
• A acidic aqueous composition
• B containing
• at least one organic compound having at least one aromatic heterocycle wherein the aromatic heterocycle has at least one nitrogen atom.
• the invention further relates to a metal surface treated according to the method of the invention and the use of this treated metal surface for the subsequent coating with an organic binder system.
• Such aqueous compositions are suitable for the corrosion-protective pretreatment and have over the classical phosphating, for example in the manufacture of automobiles, the advantage that they can be used in processes which, on the one hand, involve fewer treatment stages and, on the other hand, during operation of a pretreatment line scarcely tend to form inorganic sludges which have to be laboriously worked up in the phosphating because of their heavy metal content ,
• the phosphating with respect to the adhesion to subsequently applied lacquer layers and corrosion resistance of the crystalline phosphate layer especially on galvanized surfaces still has significant advantages over an amorphous conversion layer based on mixed oxides and hydroxides of the metals Si, Ti, Zr and Hf.
• the WO 2008/133047 discloses aqueous treatment solutions for the conversion of metal surfaces containing fluorine complexes of the metals Ti, Zr and Hf and organic compounds selected from arylamines, aminopolysaccharides, amino-modified phenols and their derivatives, which may additionally contain ions of the elements Mg, Al, Zn, Cu and Co. Furthermore, the teaches WO 2008/133047 an aqueous post-rinse containing compounds selected from phosphoric acid, amino-phenols and organic phosphorus compounds. In the course of this aftertreatment, according to the invention, certain layer weights with respect to the metallic and organic fractions on the metal surface should be realized for adequate corrosion protection.
• the US 5401337 A discloses a two-step process for steel and aluminum comprising a pretreatment, which may be a chromium-free pretreatment, and a subsequent treatment with an aqueous composition which may contain triazoles in an alternative of the teachings disclosed therein.
• the aftertreatment is to effect a sealing of the metal surfaces, so that the disclosed two-stage process is particularly suitable for the surface treatment of Aluminuim.
• the US 2008/230394 A1 discloses a one-step process for anti-corrosive and paint adhesion-enhancing first coat followed by electrodeposition.
• the initial coating is carried out by contacting with acidic compositions containing compounds of the element Zr and fluorides, wherein additionally copper (II) ions and / or inter alia nitrogen-containing rust inhibitors, which in turn may be selected from heterocyclic compounds, may be included.
• copper (II) ions and / or inter alia nitrogen-containing rust inhibitors which in turn may be selected from heterocyclic compounds, may be included.
• the method for a sequential coating with a cationic electrodeposition paint is also applicable to metallic composite constructions.
• the object of the present invention is therefore to provide a process for the corrosion-protective and adhesion-promoting treatment of a composite construction which, in addition to surfaces of zinc has at least surfaces of iron before coating with an organic binder system in which the adhesion of the subsequently applied and cured organic Binder system to the metal substrate and the corrosion protection of the same over the prior art is significantly improved, wherein in a first treatment step is always a conversion treatment with an acidic aqueous agent, the water-soluble compounds of Zr, Ti and / or Si and fluoride ion-releasing, water-soluble inorganic Contains fluorine compounds.
• surfaces of iron, steel, zinc, galvanized and alloy-galvanized iron and Steel available, for example, under the common names Galfan®, Galvalume®, Galvannealed®.
• the surfaces treated in the process according to the invention are "bare" metal surfaces.
• bare metal surfaces are meant metal surfaces that do not yet carry a corrosion-protective coating.
• the method according to the invention is thus preferably the first or only treatment step which produces a corrosion protection layer, which in turn can serve as the basis for a subsequent coating. It is therefore preferably not an after-treatment of a previously generated corrosion protection layer such as a phosphate layer.
• the corrosion-protecting and adhesion-promoting effect of the passivating pretreatment (conversion treatment) and after-treatment is increased in the process according to the invention by the presence of the water-soluble inorganic compounds which release copper ions.
• the positive effect of the aftertreatment in step iii) of the process according to the invention on the paint adhesion and the corrosion protection of subsequently applied on the metal surface organic coatings in process according to the invention is significant, since the composition (A) in the passivating pretreatment solution in step ii) water-soluble inorganic compounds contains, which release copper (II) ions.
• the use of the preferred method according to the invention is particularly advantageous when treating metal composite structures which, in addition to surfaces of zinc and the surfaces of iron, in particular also have at least surfaces of aluminum.
• an organic compound having at least one aromatic nitrogen heterocycle contained in the aqueous composition (B) of the post-treatment in step iii) preference is given to using those heterocycles which are in the ⁇ - and / or ⁇ -position a nitrogen heteroatom of the respective aromatic heterocycle are substituted, wherein the substituents in ⁇ -position and / or ⁇ -position are selected from -OR, -NRH, -COOX, -CH 2 OR, -CH 2 NRH, -CH 2 - COOX, -C 2 H 4 OR, wherein the radical R is selected in each case from hydrogen, alkyl or alkylene groups having not more than 4 carbon atoms and the radical X is selected in each case from hydrogen, alkali metals, alkyl or alkylene groups not more than 4 carbon atoms.
• the aromatic heterocycles additionally have a chelating effect on polyvalent metal cations, which are incorporated in the passivating pretreatment stage either from the metal substrate by pickling processes in the conversion or passive layer or contained in the pretreatment stage as such and with the on the substrate adhering wet film in the aftertreatment.
• Preferred aromatic heterocycles in the composition (B) of process step iii) are selected in the process according to the invention from triazole, benzotriazole, imidazole, quinoline and / or indole, particularly preferably quinoline.
• a corresponding substitution of this selection of heterocycles in ⁇ - and / or ⁇ -position to a nitrogen heteroatom with the abovementioned substituents is likewise advantageous for the effectiveness of the post-treatment stage iii) for improving the paint adhesion and the corrosion protection of subsequently applied organic coatings.
• the content of organic compounds having at least one aromatic heterocycle containing at least one nitrogen atom in the aqueous composition (B) of process step iii) is preferably at least 10 ppm, particularly preferably at least 100 ppm, but preferably does not exceed 5000 ppm, more preferably not 1000 ppm calculated as the mass fraction of the aromatic heterocycles containing at least one nitrogen atom on the composition (B).
• the mass fraction of aromatic heterocycles in the composition (B) corresponds exclusively to the proportion by mass which is predetermined by the aromatic heterocyclic structural unit without substituents.
• chelating complexing agents whose chelating substituents are selected from amino, carboxyl and / or hydroxyl groups may additionally be present in composition (B) of the after-treatment in step iii).
• Suitable chelating agents for the purposes of the present invention are in particular ⁇ -, ⁇ -, and ⁇ -amino acids.
• the additional chelating agents incorporated into the composition (B) promote the complexation of polyvalent metal cations of the slightly water-soluble metal salts contained in the conversion and passive layers, respectively. By this measure, the corrosive delamination of subsequently applied organic coatings can be further minimized.
• the proportion of chelating complexing agents in the composition (B) in process step iii) for this purpose is preferably at least 10 ppm, more preferably at least 50 ppm, but preferably not more than 1000 ppm.
• the metal surfaces to be treated are preferably freed of oil and fat residues in a purification step in step i) of the process according to the invention. At the same time, this produces a reproducible metal surface which ensures a uniform layer quality according to the process steps consisting of conversion treatment in step ii) and after-treatment in step iii). This is preferably an alkaline cleaning with commercially available products known to the person skilled in the art.
• the application of the aqueous compositions (A, B) in process steps ii) and iii) can be carried out, for example, by immersion in the treatment solution ("immersion process") or by spraying ("spraying process") with the respective composition.
• the temperature of the compositions is preferably in the range of 15 to 60 ° C, in particular in the range of 25 to 50 ° C.
• the necessary duration of treatment depends on the respective process step and the type of application.
• contact times in step ii) with the chromium-free composition (A) of at least 30 seconds, in particular at least 1 minute, are preferred.
• the contact time in step ii) of the process according to the invention should preferably not exceed 10 minutes, more preferably 5 minutes.
• the contact times in the Step iii) with the aqueous compositions (B) correspond to those of a conventional sink and are preferably in the range of a few seconds to minutes.
• a rinsing step may be carried out, more preferably water, in particular with deionized water.
• process according to the invention is particularly suitable for improving paint adhesion to subsequently applied and cured binder systems in the dipping process. Therefore, processes according to the invention are distinguished by the fact that process step iii) with intermediate rinsing step, but without drying step, is followed by electrodeposition or electroless electrophoretic dip coating.
• immersion paint refers to those aqueous dispersions of organic polymers which are applied to the metal surface in the immersion process both without external current, ie self-deposited, and those in which coating with the paint from the aqueous phase takes place by applying an external voltage source.
• the metal surface is dried after contact with the compositions (A, B) and before coating with a dip paint, for example a cathodic electrodeposition paint.
• a dip paint for example a cathodic electrodeposition paint.
• unintentional drying may occur during system downtime when the treated metal surface, such as an automobile body or part thereof, is in the air between the bath containing the agent of the invention and the dip bath.
• this unintentional drying is harmless.
• the present invention comprises a composite construction which, in addition to surfaces of zinc, also has at least surfaces of iron or, preferably, at least also surfaces of iron and aluminum which has been treated according to the method described above, the metallic surfaces of the composite construction comprising a titanium and / or Zirconium coating of preferably not less than 20 mg / m 2 and preferably not more than 150 mg / m 2 , and wherein preferably a copper coating of 100 mg / m 2 , more preferably 80 mg / m 2 not will exceed, but preferably deposited at least 10 mg / m 2 of copper deposited.
• composite structures treated in accordance with the underlying invention are used in the production of semi-finished products, in automotive production in body construction, in shipbuilding, in construction and in the field of architecture, and for the production of white goods and electronic housings.
• the correspondingly treated metal sheets were dried after the last rinsing step with compressed air and electrocoated with the following cathodic dip coating: Cathoguard 500 (Fa BASF, KTL layer thickness: 20 microns non-destructively determined with commercially available coating thickness gauge). The paint was then baked at 175 ° C for 25 min in the oven.
• compositions containing copper (II) since in this case corrosion on steel is already known the pre-treatment is strongly inhibited and then the post-treatment with the composition (B) makes the inhibition of the zinc surfaces, without resulting in a deterioration of the corrosion properties of the passivation on the iron surfaces.

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• Chemical & Material Sciences (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Electrochemistry (AREA)
• Chemical Treatment Of Metals (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Paints Or Removers (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)
• Laminated Bodies (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Applications Claiming Priority (2)

Publications (2)

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Citations (5)

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• 2009
  • 2009-07-27 DE DE102009028025A patent/DE102009028025A1/de not_active Ceased
• 2010
  • 2010-07-13 JP JP2012522084A patent/JP5684255B2/ja not_active Expired - Fee Related
  • 2010-07-13 WO PCT/EP2010/060053 patent/WO2011012443A1/de not_active Ceased
  • 2010-07-13 CN CN2010800326538A patent/CN102482783A/zh active Pending
  • 2010-07-13 BR BR112012001698A patent/BR112012001698A2/pt not_active Application Discontinuation
  • 2010-07-13 ES ES10734099.4T patent/ES2544980T3/es active Active
  • 2010-07-13 RU RU2012106611/02A patent/RU2012106611A/ru unknown
  • 2010-07-13 EP EP10734099.4A patent/EP2459770B1/de active Active
  • 2010-07-13 AU AU2010278178A patent/AU2010278178B2/en not_active Ceased
• 2012
  • 2012-01-26 US US13/358,873 patent/US8557096B2/en active Active

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