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
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/04—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in markedly acid liquids
• • 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
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/06—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in markedly alkaline liquids

Definitions

• the present invention relates to compositions for the production of anticorrosive coatings on metal surfaces, to processes for the preparation of such compositions and to their use.
• compositions of the invention are used in particular for the production of corrosion-protective conversion layers or passivation layers on metal surfaces, such as the surfaces of pure metal substrates such as zinc, aluminum, magnesium or their alloys and galvanically produced surfaces of zinc or their alloys.
• Metal parts are coated to protect against corrosion, for example, galvanically with base metals, such.
• base metals such as zinc, nickel, chromium, aluminum, magnesium and alloys of the aforementioned, and the corrosion resistance of the metal coating by forming a conversion layer, often a passivation layer further improved.
• the metal surfaces are often treated with solutions containing chromium (VI).
• chromium (VI) compounds due to the high toxicity and carcinogenicity of chromium (VI) compounds, more recent attempts have been made to prepare such conversion layers with chromium (III) -containing solutions. These chromium (III) -containing treatment liquids are added to increase the corrosion protection effect of the prepared conversion layers many times high amounts of cobalt (II) compounds.
• Recent processes produce protective layers with an organosilicon-based binder system to which corrosion inhibiting additives based on molybdenum, tungsten, titanium, zirconium, vanadium and other metals are added.
• the US-A-6,524,403 describes a chromium-free composition for improving the corrosion resistance of zinc or zinc alloy surfaces, which composition contains a source of titanium ions or titanates, an oxidizer and fluorides, and Group II metal compounds, and the composition is substantially free of silicates and silica. Strontium is used in particular as Group II metal.
• the EP 0 760 401 discloses an anticorrosive composition containing an oxidizing agent, a silicate and / or silica and metal cations selected from Ti, Zr, Ce, Sr, V, W and Mo, oxime metal anions thereof and / or fluorometal anions thereof.
• the previously known chromium-free corrosion inhibitors have the disadvantage that they either do not provide sufficient corrosion protection properties of the conversion layers or are not sufficiently stable to use them in a continuous process or both.
• the object of the present invention was to overcome the disadvantages of the known in the prior art means for producing anticorrosive layers or conversion layers on metal surfaces, in particular surfaces of zinc, aluminum, magnesium or their alloys, wherein the means free of chromium and cobalt should be.
• the agent according to the invention is characterized inter alia by containing in situ generated nanoparticles which are stable or at least metastable.
• a conversion layer or passivation layer is formed in the treatment of metal surfaces with the agent according to the invention.
• the nanoparticles generated in situ in the treatment solution are incorporated into the conversion layer during the formation of the conversion layer, thereby resulting in a particularly high corrosion protection effect of the treated metal surfaces.
• these nanoparticles are generated in situ by hydrolysis or oxidation of the substances contained in the starting solution. The nanoparticles are not added to the solution as already existing nanoparticulate particles from outside.
• inventively generated in situ nanoparticles are better incorporated into the conversion layers and thereby these layers are denser and thus more corrosion resistant than those that can be produced by applying a corrosion protection solution were added to the nanoparticles from the outside, for example in the form of a Silica or silicate solution.
• the nanoparticles in the composition according to the invention are generated in situ by physical and / or chemical treatment of the starting solution, resulting in a colloidal solution. By means of a Tyndall lamp, the formation of nanoparticles can be easily detected.
• the nanoparticles have an average particle diameter ⁇ 500 nm.
• the nanoparticles formed in step B) have an average particle diameter ⁇ 250 nm, preferably ⁇ 200 nm, particularly preferably ⁇ 150 nm.
• the nanoparticles are formed from the halogen complex anions and / or oxo cations by hydrolysis or oxidation.
• the nanoparticles thus consist essentially of the oxides of the metals or metalloids.
• the formation of nanoparticles in situ by the physical and / or chemical treatment is carried out by bringing the initially present equilibrium state of the starting solution in an imbalance state and the system in a stabilized metastable state.
• the conversion from the equilibrium state to an imbalance state can be effected by changing the temperature, changing the ion concentration, changing the pH, changing the pressure, supersaturating the solution, stirring the Solution, adding an oxidizing agent and / or adding a reducing agent done.
• the formation of the nanoparticles takes place in situ by supersaturation of the solution and / or stirring of the solution.
• composition of the invention may be provided in various forms and stages of completion prior to the treatment of metal surfaces as a commercial product.
• the agent of the invention is provided as a concentrate which is to be diluted before use.
• the product according to the invention is suitable as a commercial product as soon as the aqueous solution containing oxo-cations and halogen complex anions has been prepared according to step A) and the nanoparticles according to B) have been formed in situ .
• an oxidative substance is added, selected from hydrogen peroxide, organic peroxides, alkali metal peroxides, persulfates, perborates, nitrates and mixtures thereof, the addition of hydrogen peroxide as oxidative substance is particularly preferred.
• the addition of the oxidative substance is expediently carried out before the use of the agent according to the invention for the production of anticorrosion coatings, wherein the agent according to the invention can already be provided with the oxidative substance contained therein or the oxidative substance is added shortly before the use of the agent according to the invention at the manufacturer of the anticorrosive coatings ,
• the addition of the oxidative substance prior to the use of the agent according to the invention for the production of anticorrosive coatings causes i.a. Pre-passivation of the metallic surface, in particular a zinc or zinc alloy surface, which is advantageous because the treatment solution can be extremely aggressive against the metallic surface and could at least partially dissolve it.
• the pH is adjusted by means of an acid or base to a value in the range from 0.5 to 5.0, preferably in the range from 1.0 to 3.0, more preferably adjusted in the range of 1.3 to 2.0.
• a value in the range from 0.5 to 5.0 preferably in the range from 1.0 to 3.0, more preferably adjusted in the range of 1.3 to 2.0.
• the agent according to the invention is prepared by the formation of nanoparticles according to step B) at a temperature in the range of room temperature to 100 ° C, preferably in the range of 30 ° C to 80 ° C, more preferably in the range from 35 ° C to 50 ° C is performed.
• a temperature in the range of room temperature to 100 ° C, preferably in the range of 30 ° C to 80 ° C, more preferably in the range from 35 ° C to 50 ° C is performed.
• a temperature in the range of room temperature to 100 ° C, preferably in the range of 30 ° C to 80 ° C, more preferably in the range from 35 ° C to 50 ° C is performed.
• a temperature in the range of room temperature to 100 ° C, preferably in the range of 30 ° C to 80 ° C, more preferably in the range from 35 ° C to 50 ° C is performed.
• Too low a temperature nanoparticles are formed at an uneconomically slow rate.
• the agent is prepared by adding the halogen complex anions b) to the aqueous solution in step A) in the form of their metal salts, preferably their alkali metal salts, more preferably their sodium and potassium salts.
• their metal salts preferably their alkali metal salts, more preferably their sodium and potassium salts.
• halogen complex anions b) fluoroanions selected from BF 4 1- , TiF 6 2- , ZrF 6 2- , SiF 6 2- , AIF 6 3- and mixtures thereof.
• further metal salts are added to the aqueous solution in stage A), preferably salts of the metals B, Ti, Zr, Si and / or Al.
• the metals are added in the form of the metal halides, metal nitrates and / or metal sulfates.
• the aqueous solution prepared in step A) contains the oxo cations in a concentration of 0.1 to 0.5 wt .-%, preferably in a concentration of 0.1 to 0.3 wt. -%.
• the aqueous solution prepared in step A) contains the halogen complex anions in a concentration of 0.1 to 3.0 wt .-%, preferably in a concentration of 0.5 to 2.0 wt .-%.
• the agent of the invention may be provided as a concentrate to be diluted before use.
• the agent according to the invention may already be in the concentration or dilution suitable for the application to be provided.
• the solution obtained in step B) is expediently diluted with water in a ratio of 1: 3 to 1: 5 before or after the addition of an oxidative substance in step C).
• composition according to the invention for the production of anticorrosive coatings is carried out by direct treatment of the metal surfaces with the agent, preferably by immersing or pivoting the objects with metal surfaces in the or the agent.
• Application by dipping or panning is preferably carried out at a temperature of the treatment bath in the range of 20 to 100 ° C, preferably 30 to 70 ° C, more preferably 40 to 60 ° C, and most preferably about 50 ° C.
• the most suitable treatment time for the production of anticorrosive coatings by immersing or pivoting the objects with metal surfaces in the treatment or the treatment varies depending on various parameters, such as.
• the composition of the treatment solution, the treatment temperature, the type of metal surface and the degree of corrosion protection desired is in the range of 10 to 120 seconds, preferably in the range of 20 to 60 seconds.
• compositions according to the invention and comparative compositions an aqueous solution of oxo anions a) is prepared.
• the halogen complex anion component b in this example a fluoroanion component
• this solution is subjected to physical and / or chemical treatment by vigorous stirring (propeller stirrer, 700 to 1000 rpm).
• the formation of nanoparticles is checked by means of a Tyndall lamp.
• the solution obtained is made up to 1 l with water.
• the previously prepared solution is diluted 1 to 4 with water (1 liter of solution plus 3 liters of water) before use for the preparation of anticorrosion coatings. Subsequently, 1 liter of 10% H 2 O 2 solution is added and the pH is adjusted to 1.5 to 1.8 with NaOH or HNO 3 .
• the individual components of the solutions prepared (5 Liter of solution per batch) and the physical and / or chemical treatments are given in Table 1 below. ⁇ b> Table 1 ⁇ / b> Treatment soln. No.
• Table 1 shows that without treatment of the solutions by stirring (solutions 1b to 11b) no Tyndall effect was observed and thus no formation of nanoparticles was achieved. The same was observed when the fluoroanion component was used in the form of its free acid with and without stirring (solutions 2a, 2b, 4a, 4b, 7a, 7b, 9a, 9b, 11a and 11b).
• Galvanized sheets were treated with the previously prepared and shown in Table 1 treatment solutions by immersion in the solutions for 60 seconds at 50 ° C. The sheets were then rinsed with water and subjected to a corrosion test according to DIN 50021 SS (salt spray test) for drumware and the duration of occurrence of i) first signs of corrosion and ii) 5% white rust compared. The results are shown in Table 2.
• Table 2 ⁇ / b> Treatment soln. No. first signs of corrosion 5% white rust 1a (invention) 8 h 24 hours 1b (Comp. Ex.) 3 h 8 h 2a (Comp. Ex.) 2 h 7 h 2b (Comp.

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• Chemical & Material Sciences (AREA)
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• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Chemical Treatment Of Metals (AREA)

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• 2007
  • 2007-03-29 EP EP07105237.7A patent/EP1978131B2/fr active Active
  • 2007-03-29 ES ES07105237T patent/ES2388302T5/es active Active
• 2008
  • 2008-03-20 CN CN2008800104018A patent/CN101668881B/zh active Active
  • 2008-03-20 US US12/593,632 patent/US8764916B2/en active Active
  • 2008-03-20 KR KR1020097020409A patent/KR101493458B1/ko active Active
  • 2008-03-20 JP JP2010500230A patent/JP5279811B2/ja active Active
  • 2008-03-20 WO PCT/EP2008/053346 patent/WO2008119675A1/fr not_active Ceased
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