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
  • C23C22/60—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 alkaline aqueous solutions with pH greater than 8
• • 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
  • C23C22/73—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 characterised by the process
• • 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

Definitions

• the invention relates to a method for producing conversion coatings on surfaces of zinc or zinc alloys, in which in a first step the surfaces are brought into contact with a solution containing at least two different polyvalent metal ions and complexing agents in such an amount that the polyvalent metal ions are kept in solution, and has a pH ⁇ 11, and in which rinsing with a rinsing solution is carried out in a subsequent stage, and its use as a pretreatment for subsequent painting, film coating or adhesive coating.
• Such a method for producing a conversion layer is known in particular from DE-C-1 521 854 as pretreatment before painting and film coating.
• aqueous alkaline solutions which act as so-called non-alkali metal ions of one or more of the metals silver, magnesium, cadmium, aluminum, tin, titanium, antimony, molybdenum, chromium, cerium, tungsten, manganese, cobalt , Iron and nickel included.
• Particularly suitable solutions are those which contain ions of iron or cobalt with another of the metals mentioned as non-alkali metal ions.
• the solutions contain sufficient organic complexing agents to keep the non-alkali metal ions in solution.
• the conversion coatings produced by means of these ions increase the corrosion resistance and improve the adhesion of subsequently applied organic coatings.
• Corrosion resistance and adhesion are further improved if the surfaces are rinsed with an acidic, hexavalent chromium and possibly additionally trivalent chromium solution after the conversion layer has been produced.
• the object of the invention is to provide a method for producing conversion coatings on surfaces made of zinc or zinc alloys, which avoids the disadvantages of the known method and in particular does not or only to a very small extent burden the environment and is at least equally good in terms of corrosion protection and paint adhesion behaves.
• the object is achieved by designing the method of the type mentioned at the outset in accordance with the invention in such a way that rinsing is carried out with a rinsing solution which contains aluminum, zirconium and fluoride and is adjusted to a pH ⁇ 5.
• the method according to the invention is suitable for all surfaces which contain zinc or zinc alloys, such as, for example, materials made of solid zinc or solid zinc alloys, but also for those whose surface is electrolytically galvanized or alloy-galvanized by deposition from the gas phase or in the hot-dip process has been.
• zinc or zinc alloys such as, for example, materials made of solid zinc or solid zinc alloys, but also for those whose surface is electrolytically galvanized or alloy-galvanized by deposition from the gas phase or in the hot-dip process has been.
• Aluminum, silicon, lead, iron, nickel, cobalt and manganese are particularly suitable alloying partners for zinc.
• both one-sided and two-sided galvanizing or alloy galvanizing can be present.
• the surfaces should be bare and as free of grease as possible. If necessary, they are cleaned alkaline, neutral or acidic before the conversion treatment and then expediently rinsed with water.
• the application of the alkaline solution used in the first stage can e.g. in spraying, dipping or flooding.
• alkaline solutions have been found to be those containing iron (III) ions and additionally cobalt and / or nickel and / or chromium (III) and / or aluminum ions, the total content of which was between 0.3 and 3 g / l, preferably between 0.4 and 1.2 g / l.
• the polyvalent metal ions can be used as salts of inorganic acids, for example nitric acid, or as salts of organic acids, for example formic acid, in particular also Acetic acid can be used. Salts of organic acids, which can simultaneously serve as complexing agents, are also suitable.
• Amphoteric metals, such as aluminum, can also be dissolved in the form of the hydroxyl complex without an additional anion or complexing agent.
• organic chelating agents of various types can be used as complexing agents: for example dicarboxylic acids (malonic acid, fumaric acid etc.); Amino acids (eg glycine); Hydroxycarboxylic acids (e.g. citric acid, gluconic acid, lactic acid); 1,3-diketones (e.g. acetylacetone); aliphatic polyalcohols (e.g. sorbitol, 1,2-ethanediol); aromatic carboxylic acids (eg salicylic acid, phthalic acid); Aminocarboxylic acid (e.g. ethylenediaminetetraacetic acid).
• Other complexing agents such as methanephosphonic acid diethanolamide, can also be used.
• the solution must contain at least such an amount of complexing agent that the multivalent metal ions present can be bound in a completely complex manner.
• the content of complexing agents must also be increased. Since increasing amounts of certain complexing agents, which are acidic in nature, can reduce the alkalinity of the solution, complexing agents are preferably used in Form of neutral salts, especially the alkali metal salts used. It has been found that excess amounts of complexing agents are of no benefit.
• salts of gluconic acid but especially hexahydroxyheptanoic acid
• the content of complexing agent in the solution should be between 0.05 and 10 g / l, in most applications between 1.5 and 5.5 g / l (based on the sodium salt of hexahydroxyheptanoic acid).
• the aqueous solution must have a pH ⁇ 11.
• the best results are achieved in the pH range from 12.2 to 13.3.
• the adjustment of the pH value can e.g. by triethanolamine, alkali metal hydroxides, alkali metal carbonates, alkali metal phosphates, alkali metal polyphosphates, alkali metal pyrophosphates, alkali metal borates, alkali metal silicates or mixtures thereof.
• the most advantageous are alkali hydroxides, especially sodium hydroxide.
• the temperature of the solution of the first stage can in principle be between 20 ° C and 90 ° C.
• the preferred temperature range is 45 to 65 ° C.
• the treatment time is usually 2 to 60 seconds, preferably 5 to 30 seconds. It depends, among other things, on the application technology. For example, the duration of treatment in spraying is shorter than in diving under otherwise the same circumstances.
• solutions with a lower metal ion concentration require higher temperatures and longer treatment times than those with a higher metal ion concentration.
• excess treatment solution should be removed as far as possible from the zinc or zinc alloy surface. This can e.g. by draining, squeezing, blowing off or rinsing with water or with an aqueous solution which has been acidified, for example with an inorganic or organic acid (hydrofluoric acid, boric acid, nitric acid, formic acid, acetic acid etc.).
• an inorganic or organic acid hydrofluoric acid, boric acid, nitric acid, formic acid, acetic acid etc.
• the application of the rinse solution can e.g. by dipping, flooding, spraying or rolling.
• a preferred embodiment of the invention consists in rinsing with a solution which contains aluminum, zirconium and fluoride in a total concentration Al + Zr + F between 0.1 and 8 g / l, preferably between 0.2 and 5 g / l.
• the molar ratios Al: Zr: F should advantageously be set to (0.15 to 8): 1: (5 to 52), in particular to (0.15 to 2.0): 1: (5 to 16).
• the Al: Zr: F ratio in the rinse solution is (0.15 to 0.67): 1: (5 to 7).
• the pH is set to 2 to 5.
• the rinse solutions used in the process according to the invention contain, inter alia, acidic aluminum fluorozirconates and, in the case of an excess of aluminum, other salts of aluminum (for example fluorides, Tetrafluoroborates, nitrates). They can be produced, for example, by first dissolving metallic zirconium or zirconium carbonate in aqueous hydrofluoric acid, with complex fluorozirconic acid being formed. Then metallic aluminum or aluminum hydroxide or an aluminum salt, for example nitrate, fluoride, tetrafluoroborate, formate, acetate, preferably in dissolved form, is added and, if necessary, dissolved. A possible slight clouding of the solution does not affect the effectiveness. Although the described manufacturing route is preferred, the solutions can also be prepared in other ways.
• the pH of the solution is preferably adjusted with cations of volatile bases. These include in particular ammonium, ethanolammonium and di- and tri-ethanolammonium.
• volatile bases include in particular ammonium, ethanolammonium and di- and tri-ethanolammonium.
• the surfaces provided with a conversion coating are rinsed with an aqueous solution which additionally contain at least one of the anions benzoate, caprylate, ethylhexoate, salicylate in a total concentration of preferably 0.05 to 0.5 g / l.
• anions can be introduced via the corresponding acids or their salts.
• the duration of the application of the rinse solution is between about 1 and 120 seconds, in particular between 1 and 30 seconds.
• the application temperature can be between 20 ° C and 80 ° C. Temperatures between 20 and 50 ° C are preferred.
• Demineralized or low-salt water is preferably used for the preparation of the rinse bath. Water with a high salt content is less suitable for bath preparation.
• the surface can e.g. air-dried or oven-dried, if necessary rinsed with deionized water beforehand.
• An advantageous embodiment of the invention provides that the surface is accelerated after the passivating rinsing, e.g. dry with hot air or infrared radiation.
• the method according to the invention serves primarily as preparation of the zinc or zinc alloy surfaces before painting, film coating or the application of adhesives. It increases the adhesion of the organic films to the metallic substrate, improves their resistance to blistering when exposed to corrosion and inhibits the corrosion penetration from damage points in the film.
• the sheets were then rinsed with water and rinsed passively. For this purpose, the sheets were immersed in the rinse solution for 5 seconds and then excess solution was removed by squeezing. After a drying time of 0.5 min in a forced air oven at 75 ° C, the pretreated sheets were coated with an epoxy primer and an acrylate top coat. The layer thickness of the total lacquer was approx. 25 ⁇ m.
• the treated sheets were then subjected to the following tests:
• the proportion of the chipped paint surface of the total curved surface is given as the tested size in%.
• the rinsing solutions used were diluted 1.6 g / l (rinsing solution A) or 20 g / l (rinsing solution B) of an aqueous concentrate with 0.855% by weight Al and 8.62% by weight Zr and 10 , 7 wt .-% F using deionized water.
• the pH in both solutions had been adjusted to approximately 3.6 with ammonia.
• Rinse A Al 0.014 g / l Zr 0.14 g / l F 0.17 g / l NH4 0.016 g / l Rinse solution B: Al 0.17 g / l Zr 1.72 g / l F 2.14 g / l NH4 0.40 g / l Rinse solution C: Cr6+ 2.0 g / l Cr3+ 0.8 g / l F 0.2 g / l Zn 0.3 g / l

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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)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

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Publications (2)

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Cited By (3)

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Citations (6)

Family Cites Families (1)

• 1990
  • 1990-05-29 DE DE4017186A patent/DE4017186A1/de not_active Withdrawn
• 1991
  • 1991-04-29 DE DE59102544T patent/DE59102544D1/de not_active Expired - Fee Related
  • 1991-04-29 EP EP91201020A patent/EP0459549B1/fr not_active Expired - Lifetime
  • 1991-04-29 AU AU76178/91A patent/AU633728B2/en not_active Ceased
  • 1991-04-29 ES ES91201020T patent/ES2057734T3/es not_active Expired - Lifetime
  • 1991-05-06 CA CA002041892A patent/CA2041892C/fr not_active Expired - Fee Related
  • 1991-05-28 JP JP03152482A patent/JP3083872B2/ja not_active Expired - Fee Related
  • 1991-05-28 BR BR919102173A patent/BR9102173A/pt unknown
  • 1991-05-29 ZA ZA914085A patent/ZA914085B/xx unknown

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