EP0126498A1 - Process for the corrosion protection of metals - Google Patents

Process for the corrosion protection of metals Download PDF

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Publication number
EP0126498A1
EP0126498A1 EP84200397A EP84200397A EP0126498A1 EP 0126498 A1 EP0126498 A1 EP 0126498A1 EP 84200397 A EP84200397 A EP 84200397A EP 84200397 A EP84200397 A EP 84200397A EP 0126498 A1 EP0126498 A1 EP 0126498A1
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EP
European Patent Office
Prior art keywords
synthetic resin
cationic
phosphate layer
corrosion protection
phosphate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP84200397A
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German (de)
French (fr)
Other versions
EP0126498B1 (en
Inventor
Peter Jörns
Werner Dr. Rausch
Gisela Rossmann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GEA Group AG
Continentale Parker Ste
Continentale Parker SA
Original Assignee
Metallgesellschaft AG
Continentale Parker Ste
Continentale Parker SA
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
    • B05D7/16—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies using synthetic lacquers or varnishes
    • 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 corrosion protection of metals, in particular iron and steel, by applying a phosphate layer and impregnating the phosphate layer with organic synthetic resin.
  • the pH of the solution used is usually in the alkaline range, which is the case when treating metal surfaces provided with conversion coatings may be associated with the disadvantage of partial delamination.
  • the object of the invention is to provide a method which does not have the disadvantages of the known methods and which provides surfaces with excellent corrosion protection and high abrasion resistance.
  • 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 a phosphate layer with a basis weight of at least 8 g / m 2 is first produced on the metal surface and at least electrolessly by means of an aqueous solution or dispersion of a cationic synthetic resin 8 g / m 2 synthetic resin applied and baked.
  • An advantageous development of the method according to the invention provides for a maximum of 40 g / m 2 of synthetic resin to be applied. Higher application weights practically no longer provide additional corrosion protection.
  • phosphate is the only anion in the acidic, aqueous phosphating solution.
  • anions such as nitrate, nitrite, chloride, sulfate, chlorate, fluoride, complex fluoride, citrate, are present zidtician to accelerate the layer formation and to establish the required A in the bathrooms often.
  • the phosphating baths are particularly suitable for the process according to the invention, in which at least a considerable proportion of the iron pickled during the layer formation remains in solution as divalent iron.
  • the concentration of the phosphating baths is preferably chosen between 20 and 120 points.
  • the application temperature is usually in the range of 40 to 98 ° C.
  • the immersion process is preferred for layer formation because it allows the layer weight limit required in the invention to be maintained in a simpler manner than the spray process.
  • the phosphating times are usually 4 to 30 minutes.
  • the cationic synthetic resins used in the impregnation process according to the invention can be partially or fully neutralized with organic acids or phosphoric acid in the aqueous medium as an emulsion, dispersion and / or colloidal solution.
  • the solids content is preferably 5 to 25% by weight.
  • the cationic synthetic resins are selected from the group of polycondensation and polymerization resins and are given their cationic function e.g. by basic nitrogen-containing groups which form cations after the addition of acid in an aqueous medium.
  • Cationic acrylate resins can be obtained, for example, by copolymerizing N, N-dimethylaminoethyl methacrylate.
  • Cationic resins can also be prepared by reacting Mannich bases of bisphenol A with epoxy resins. Modified epoxy resins which have been made acid-soluble by addition of an amine and in which crosslinking is made possible by addition of a half-capped diisocyanate during baking are particularly suitable for the process according to the invention.
  • the cationic resin from an aqueous solution or dispersion which additionally most of the lacquer and ink formulation - th additives and modifiers such as dyes, fillers - and K orrosionstikpigmente, soluble corrosion inhibitors, organic solvents and / or additives for an improved film flow as well as to support the cross-linking process when baking.
  • the lacquer and ink formulation - th additives and modifiers such as dyes, fillers - and K orrosionstikpigmente, soluble corrosion inhibitors, organic solvents and / or additives
  • the L are ackformulmaschineen suitable for the novel process, among others, which are for the cathodic electrodeposition of metals using. In the context of the invention, they are successfully used as an aqueous medium containing cationic synthetic resin without the use of electric current.
  • the organic impregnation film is applied by wetting the phosphated surface with the aqueous solution or dispersion containing the cationic synthetic resin.
  • the wetting can be carried out by spraying on, pouring over, immersing and, if appropriate, subsequently spinning off excess liquid.
  • a further advantageous embodiment of the invention provides for the cationic synthetic resin to be applied by wetting it at least twice with brief drying and subsequent baking.
  • the intermediate drying should be performed to such an extent until the film has a sufficient mechanical strength h at reach.
  • the baking which concludes the application of the cationic synthetic resin, is usually carried out at object temperatures between 160 and 200 ° C. and holding times of 5 to 30 minutes.
  • An advantageous further development of the invention is to post-assivierstoffn to further improve the corrosion protection, the phosphate layer prior to the application of the cationic synthetic resin -containing known per se Cr (VI) aqueous P.
  • They can be formulated based on chromic acid, chromium chromate, alkali dichromate and the like.
  • the method according to the invention is particularly suitable for high-quality corrosion protection of mass parts from the functional area.
  • Typical workpieces are screws, nuts, washers, springs, fasteners, brake parts and the like.
  • the protective value of the layers produced by the process according to the invention is usually significantly higher than that of chromated, electrolytically produced zinc and cadmium layers.
  • Degreasing or referred to in the first e ntrostung and descaling according to the third may be omitted if the parts to be treated are free of grease or rust or scale-free.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Paints Or Removers (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)

Abstract

A heavy phosphate coating, of at least 8 g/m<2>, is formed on a metal surface by applying a phosphating solution to the surface and a resin coating of at least 8 g/m<2> is then formed by electroless application of an aqueous composition of cationic resin, followed by stoving. The resultant coated surfaces have good corrosion protection.

Description

Die Erfindung betrifft ein Verfahren zum Korrosionsschutz von Metallen, insbesondere von Eisen und Stahl, durch Aufbringen einer Phosphatschicht und Imprägnieren der Phosphatschicht mit organischem Kunstharz.The invention relates to a method for corrosion protection of metals, in particular iron and steel, by applying a phosphate layer and impregnating the phosphate layer with organic synthetic resin.

Es ist bekannt, auf Metalloberflächen Schutzüberzüge aufzubringen, um die Korrosionsbeständigkeit zu verbessern. Hierzu werden üblicherweise die Metalloberflächen mit Lösungen in Berührung gebracht, die einen Phosphatüberzug ausbilden.It is known to apply protective coatings to metal surfaces in order to improve the corrosion resistance. For this purpose, the metal surfaces are usually brought into contact with solutions which form a phosphate coating.

Die Erzeugung der Phosphatüberzüge geschieht im allgemeinen nach dem Verfahrensschema

  • Reinigung,
  • Wasserspülung,
  • Bildung des Phosphatüberzuges,
  • Wasserspülung.
The phosphate coatings are generally produced according to the process scheme
  • Cleaning,
  • Water flushing,
  • Formation of the phosphate coating,
  • Water flushing.

Zur weiteren Verbesserung des so erhaltenen Phosphatüberzuges ist es üblich, eine Behandlung mit einer Nachbehandlungslösung anzuschließen. Neben der Nachspülung mit Lösungen auf Chromatbasis ist es zur Nachbehandlung von Phosphatüberzügen bekannt, eine nicht zusammenhängende Dichtungsschicht eines hydrophobmachenden Mittels, z.B. unter Verwendung organischer Stoffe, etwa auf Basis Polyisocyanat modifizierter Harzkondensationsprodukte (DE-AS 11 47 820) zu erzeugen bzw. mit trochnenden Ölen oder niedrigviskosen Lacken abzudichten (H. Fortmann "Nachbehandlungsverfahren phosphatierter Eisenteile", Metallwaren-Industrie und Galvanotechnik MSV Nr. 6 (1943), Seite 229). Diese Mittel konnten sich jedoch gegenüber den chromhaltigen Nachbehandlungslösungen aus Gründen niederer Qualität nicht durchsetzen. Zudem führten zahlreiche dieser Mittel nicht zu brauchbaren Ergebnissen.To further improve the phosphate coating obtained in this way, it is customary to follow up with a treatment with an aftertreatment solution. In addition to rinsing with chromate-based solutions, it is also used for the after-treatment of Phosphate coatings known to produce a non-contiguous seal layer of a hydrophobic rendering means, for example using organic materials, such as modified on the basis of polyisocyanate resin condensation products (D E-AS 11 47 820) and sealed with trochnenden oils or low-viscosity varnish (H. F ortmann "post-treatment method phosphated iron parts ", metal goods industry and electroplating MSV No. 6 (1943), page 229). However, these agents could not prevail over the chrome-containing aftertreatment solutions for reasons of low quality. In addition, many of these funds did not lead to useful results.

Weiterhin ist es bekannt, chemisch aufgebrachte Umwandlungsüberzüge, insbesondere Phosphatüberzüge, auf Metallen mittels Lösungen nachzubehandeln, die eine Poly-4-vinyl- phenolverbindung der Formel

Figure imgb0001
enthält. Hierbei sind

  • n eine Zahl zwischen 5 und 100,
  • x unabhängig voneinander Wasserstoff und/oder CRR1OH-Gruppen mit R und R1= Wasserstoff, aliphatischem und/oder aromatischem Rest mit 1 bis 12 Kohlenstoffatomen (DE-OS 31 46 265).
Furthermore, it is known to post-treat chemically applied conversion coatings, in particular phosphate coatings, on metals by means of solutions which are a poly-4-vinylphenol compound of the formula
Figure imgb0001
 contains. Here are
  • n is a number between 5 and 100,
  • x independently of one another hydrogen and / or CRR 1 OH groups with R and R 1 = hydrogen, aliphatic and / or aromatic radical with 1 to 12 carbon atoms (DE-OS 31 46 265).

Der pH-Wert der zum Einsatz kommenden Lösung liegt üblicherweise im alkalischen Bereich, was bei der Behandlung von mit Umwandlungsüberzügen versehenen Metalloberflächen gegebenenfalls mit dem Nachteil einer teilweisen Schichtablösung verbunden sein kann.The pH of the solution used is usually in the alkaline range, which is the case when treating metal surfaces provided with conversion coatings may be associated with the disadvantage of partial delamination.

Schließlich ist es auch bekannt, Phosphatschichten zunächst mit Cr-(VI)haltigen Lösungen nachzuspülen, ein Vorgang der üblicherweise zum Phosphatierprozeß gerechnet wird, und dann mit anorganischen Verbindungen, Ölen, Wachsen oder Lacken nachzubehandeln (W. Rausch, "Die Thosphatierung von Metallen" Eugen G. Leuze Verlag, Saalgau Württ. 1974, Seite 120). Obgleich diese Behandlungen einen Korrosionsschutz verleihen, der bis an den Schutzwert von verzinkten, chromatierten Oberflächen heranreicht, sind sie bei höheren Beanspruchungen nicht mehr zufriedenstel- lend. Nachteilig ist auch, daß diese Art Imprägnierung häufig flüssige, weiche bis halbharte Filme von nur geringer Abriebbeständigkeit liefert.Finally, it is also known to rinse phosphate layers first with Cr- (VI) -containing solutions, a process that is usually included in the phosphating process, and then to treat them with inorganic compounds, oils, waxes or varnishes (W. Rausch, "The Thosphating of Metals" Eugen G. Leuze Verlag, Saalgau Württ. 1974, page 120). Although these treatments provide protection against corrosion, which reaches as far as the protection value of galvanized chromated surfaces, they are no longer satisfied stel at higher loads - lend. Another disadvantage is that this type of impregnation often provides liquid, soft to semi-hard films with only low abrasion resistance.

Aufgabe der Erfindung ist es, ein Verfahren bereitzustellen, das die Nachteile der bekannten Verfahren nicht aufweist und Oberflächen mit ausgezeichnetem Korrosionsschutz sowie hoher Abriebbeständigkeit liefert.The object of the invention is to provide a method which does not have the disadvantages of the known methods and which provides surfaces with excellent corrosion protection and high abrasion resistance.

Die Aufgabe wird gelöst, indem das Verfahren der eingangs genannten Art entsprechend der Erfindung derart ausgestaltet wird, daß man auf der Metalloberfläche zunächst eine Phosphatschicht mit einem Flächengewicht von mindestens 8 g/m2 erzeugt und mittels einer wäßrigen Lösung oder Dispersion eines kationischen Kunstharzes stromlos mindestens 8 g/m2 Kunstharz aufbringt und einbrennt.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 a phosphate layer with a basis weight of at least 8 g / m 2 is first produced on the metal surface and at least electrolessly by means of an aqueous solution or dispersion of a cationic synthetic resin 8 g / m 2 synthetic resin applied and baked.

Überraschenderweise führt gerade die Kunstharzbeschichtung derartig dicker Phosphatschichten zu Erzeugnissen mit sehr hohen Korrosionsschutzwerten, was im Gegensatz zu der herrschenden Meinung steht, daß mit Kunstharz zu behandelnde Phosphatschichten dünn sein sollen (vgl. z.B. W. Rausch "Die Phosphatierung von Metallen" Eugen G. Leuze Verlag, Saalgau Württ. 1974, Seite 142).Surprisingly, the synthetic resin coating of such thick phosphate layers leads to products with very high corrosion protection values, which is contrary to the prevailing opinion that phosphate layers to be treated with synthetic resin should be thin (see, for example, W. Rausch "The Phosphating of Metals" Eugen G. Leuze Verlag, Saalgau Württ. 1974, page 142).

Eine vorteilhafte Weiterbildung des erfindungsgemäßen Verfahrens sieht vor, maximal 40 g/m2 Kunstharz aufzubringen. Höhere Auftragsgewichte liefern praktisch keinen zusätzlichen Korrosionsschutz mehr.An advantageous development of the method according to the invention provides for a maximum of 40 g / m 2 of synthetic resin to be applied. Higher application weights practically no longer provide additional corrosion protection.

Zur Erzeugung der Phosphatschichten werden an sich bekannte Phosphatierverfahren mit Zink, Zink + Eisen, Mangan, Mangan + Zink, Mangan + Eisen, Mangan + Zink + Eisen, Zink + Calcium und Zink + Calcium + Eisen als schichtbildende Kationen verwendet.In order to produce the phosphate layers, known phosphating processes with zinc, zinc + iron, manganese, manganese + zinc, manganese + iron, manganese + zinc + iron, zinc + calcium and zinc + calcium + iron are used as layer-forming cations.

Zur Modifizierung der Schichtbildung können im Phosphatierbad noch weitere Kationen, z.B. Ni, Cu, Mg, Alkali, Ammonium, zugegen sein. Bei den nicht beschleunigten Langzeitphosphatierverfahren ist Phosphat das einzige Anion in der sauren, wäßrigen Phosphatierlösung. Zur Beschleunigung der Schichtbildung und zur Einstellung der erforderlichen Azidität sind in den Bädern häufig noch weitere Anionen, z.B. Nitrat, Nitrit, Chlorid, Sulfat, Chlorat, Fluorid, komplexes Fluorid, Zitrat, anwesend.To modify the layer formation, further cations, for example Ni, Cu, Mg, alkali, ammonium, can be present in the phosphating bath. In the non-accelerated long-term phosphating process, phosphate is the only anion in the acidic, aqueous phosphating solution. Further anions such as nitrate, nitrite, chloride, sulfate, chlorate, fluoride, complex fluoride, citrate, are present zidität to accelerate the layer formation and to establish the required A in the bathrooms often.

Für das erfindungsgemäße Verfahren eignen sich insbesondere die Phosphatierbäder, in denen mindestens ein erheblicher Anteil des während der Schichtbildung abgebeizten Eisens als zweiwertiges Eisen in Lösung bleibt.The phosphating baths are particularly suitable for the process according to the invention, in which at least a considerable proportion of the iron pickled during the layer formation remains in solution as divalent iron.

Die Konzentration der Phosphatierbäder wird vorzugsweise zwischen 20 und 120 Punkten gewählt. Die Anwendungstemperatur liegt meist im Bereich von 40 bis 98 °C. Zur Schichtbildung wird das Tauchverfahren vorgezogen, weil es in einfacherer Weise als das Spritzverfahren die Einhaltung der in der Erfindung geforderten SChichtgewichtsgrenze erlaubt. Die Phosphatierzeiten betragen üblicherweise 4 bis 30 min.The concentration of the phosphating baths is preferably chosen between 20 and 120 points. The application temperature is usually in the range of 40 to 98 ° C. The immersion process is preferred for layer formation because it allows the layer weight limit required in the invention to be maintained in a simpler manner than the spray process. The phosphating times are usually 4 to 30 minutes.

Die im erfindungsgemäßen Verfahren zur Imprägnierung benutzten kationischen Kunstharze können mit organischen Säuren oder Phosphorsäure teilweise oder voll neutralisiert in dem wäßrigen Medium als Emulsion, Dispersion und/ oder kolloidale Lösung vorliegen. Der Festkörpergehalt beträgt vorzugsweise 5 bis 25 Gew.%.The cationic synthetic resins used in the impregnation process according to the invention can be partially or fully neutralized with organic acids or phosphoric acid in the aqueous medium as an emulsion, dispersion and / or colloidal solution. The solids content is preferably 5 to 25% by weight.

Die kationischen Kunstharze werden aus der Gruppe der Polykondensations- und Polymerisationsharze ausgewählt und erhalten ihre kationische Funktion z.B. durch basische Stickstoff-enthaltende Gruppen, die nach Zugabe von Säure im wäßrigen Medium Kationen bilden. Kationische Acrylatharze sind beispielsweise durch Einpolymerisation von N, N-Dimethylaminoäthylmethacrylat erhältlich. Ferner lassen sich kationische Harze durch Umsetzung von Mannich-Basen des Bisphenols A mit Epoxidharzen herstellen. Besonders gut sind modifizierte Epoxidharze für das erfindungsgemäße Verfahren geeignet, die durch Addition eines Amins säurelöslich gemacht wurden und bei denen durch Addition eines halbseitig verkappten Diisocyanats während des Einbrennens eine Vernetzung ermöglicht ist.The cationic synthetic resins are selected from the group of polycondensation and polymerization resins and are given their cationic function e.g. by basic nitrogen-containing groups which form cations after the addition of acid in an aqueous medium. Cationic acrylate resins can be obtained, for example, by copolymerizing N, N-dimethylaminoethyl methacrylate. Cationic resins can also be prepared by reacting Mannich bases of bisphenol A with epoxy resins. Modified epoxy resins which have been made acid-soluble by addition of an amine and in which crosslinking is made possible by addition of a half-capped diisocyanate during baking are particularly suitable for the process according to the invention.

Weiterhin ist es vorteilhaft, das kationische Kunstharz aus einer wäßrigen Lösung oder Dispersion aufzubringen, die zusätzlich aus der Lack- und Farbformulierung bekann- ten Zusätze und Modifizierungsmittel, wie Farb-, Füll- und Korrosionsschutzpigmente, lösliche Korrosionsinhibitoren, organische Lösungsmittel und/oder Additive für einen verbesserten Filmverlauf sowie zur Unterstützung des Vernetzungsvorganges beim Einbrennen, enthalten.Furthermore, it is advantageous to apply the cationic resin from an aqueous solution or dispersion which additionally most of the lacquer and ink formulation - th additives and modifiers such as dyes, fillers - and K orrosionsschutzpigmente, soluble corrosion inhibitors, organic solvents and / or additives for an improved film flow as well as to support the cross-linking process when baking.

Für das erfindungsgemäße Verfahren sind u.a. auch die Lackformulierungen geeignet, die für die kathodische Elektrotauchlackierung von Metallen Verwendung finden. Im Rahmen der Erfindung werden sie mit Erfolg als kationisches Kunstharz enthaltendes wäßriges Medium ohne Anwendung elektrischen Stromes eingesetzt.And the L are ackformulierungen suitable for the novel process, among others, which are for the cathodic electrodeposition of metals using. In the context of the invention, they are successfully used as an aqueous medium containing cationic synthetic resin without the use of electric current.

Die Aufbringung des organischen Imprägnierfilms erfolgt durch Benetzung der phosphatierten Oberfläche mit der das kationische Kunstharz enthaltenden wäßrigen Lösung oder Dispersion. Die Benetzung kann durch Aufspritzen, Übergießen, Eintauchen und gegebenenfalls anschließendes Abschleudern von überschüssiger Flüssigkeit durchgeführt werden.The organic impregnation film is applied by wetting the phosphated surface with the aqueous solution or dispersion containing the cationic synthetic resin. The wetting can be carried out by spraying on, pouring over, immersing and, if appropriate, subsequently spinning off excess liquid.

Um zu vermeiden, daß nach einmaliger Benetzung Fehlstellen im organischen Film zurückbleiben bzw. wenn hohe Auflagegewichte beabsichtigt sind, sieht eine weitere vorteilhafte Ausgestaltung der Erfindung vor, das kationische Kunstharz durch mindestens zweimaliges Benetzen mit kurzzeitigem Zwischentrocknen und abschließendem Einbrennen aufzubringen.In order to prevent defects from remaining in the organic film after a single wetting or when high coating weights are intended, a further advantageous embodiment of the invention provides for the cationic synthetic resin to be applied by wetting it at least twice with brief drying and subsequent baking.

Die Zwischentrocknung sollte soweit geführt werden, bis der Film eine ausreichende mechanische Festigkeit erreicht hat.The intermediate drying should be performed to such an extent until the film has a sufficient mechanical strength h at reach.

Das den Auftrag des kationischen Kunstharzes abschließende Einbrennen erfolgt üblichrweise bei Objekttemperaturen zwischen 160 und 200 °C und Haltezeiten von 5 bis 30 min.The baking, which concludes the application of the cationic synthetic resin, is usually carried out at object temperatures between 160 and 200 ° C. and holding times of 5 to 30 minutes.

Eine vorteilhafte Weiterbildung der Erfindung besteht darin, zur weiteren Verbesserung des Korrosionsschutzes die Phosphatschicht vor dem Aufbringen des kationischen Kunstharzes mit an sich bekannten Cr(VI)-haltigen wäßrigen Passiviermitteln nachzubehandeln. Sie können auf Basis von Chromsäure, Chromchromat, Alkalidichromat und dergleichen formuliert sein.An advantageous further development of the invention is to post-assiviermitteln to further improve the corrosion protection, the phosphate layer prior to the application of the cationic synthetic resin -containing known per se Cr (VI) aqueous P. They can be formulated based on chromic acid, chromium chromate, alkali dichromate and the like.

Eine Nachbehandlung im Anschluß an das Einbrennen des kationischen Kunstharzes mit einem Korrosionsschutzöl stellt eine weitere vorteilhafte Ausführungsform der Erfindung dar. Hierdurch wird der Korrosionsschutz häufig weiter heraufgesetzt und der Oberfläche, insbesondere nach Behandlung als Schüttgut, ein ansprechendes gleichmäßig glänzendes Aussehen vermittelt. Eine anschließende Lackierung ist nicht vorgesehen.Aftertreatment following the stoving of the cationic synthetic resin with an anticorrosive oil is another advantageous embodiment of the invention As a result, the corrosion protection is often further increased and the surface, in particular after treatment as bulk material, is given an appealing, uniformly shiny appearance. Subsequent painting is not planned.

Das erfindungsgemäße Verfahren eignet sich insbesondere zum hochwertigen Korrosionsschutz von Massenteilen aus dem funktionellen Bereich. Typische Werkstücke sind Schrauben, Muttern, Unterlegscheiben, Federn, Befestigungselemente, Bremsteile und dergleichen. Der Schutzwert der nach dem erfindungsgemäßen Verfahren erzeugten Schichten liegt meist deutlich über dem von chromatierten, elektrolytisch erzeugten Zink- und Cadmiumschichten.The method according to the invention is particularly suitable for high-quality corrosion protection of mass parts from the functional area. Typical workpieces are screws, nuts, washers, springs, fasteners, brake parts and the like. The protective value of the layers produced by the process according to the invention is usually significantly higher than that of chromated, electrolytically produced zinc and cadmium layers.

Ein für das erfindungsgemäße Verfahren typischer Verfahrensgang umfaßt beispielsweise folgende Arbeitsstufen:

  • 1. Entfettung: Stark alkalischer, wäßriger Tauchreiniger; wäßriger Spritzreiniger, organische Lösungsmittel;
  • 2. Spülung mit Wasser;
  • 3. Entrostung und Entzunderung: Wäßrige Salzsäure, Schwefelsäure oder Phosphorsäure, gegebenenfalls auch Strahlen oder Schleifen;
  • 4. Spülung mit Wasser;
  • 5. Vorspülung: Warmwasser, gegebenenfalls unter Zusatz von Aktivierungsmittel;
  • 6. Phosphatierung;
  • 7. Spülung mit Wasser;
  • 8. Passivierende Nachspülung: Chrom(VI)-Chrom(III)-haltiges, wäßriges Nachspülmittel;
  • 9. Trocknung (falls gewünscht);
  • 10. Imprägnierung mit kationischem Kunstharz: Pigmentierte Lösung/Emulsion eines kationischen, modifizierten Kunstharzes; Festkörpergehalt: 25 %; 25 °C; 1 min Tauchen, danach Antrocknen an der Luft; noch einmal l min Tauchen;
  • 11. Aushärtung des Imprägnierungsfilms: 20 min Einbrennen bei 185 °C Objekttemperatur.
A typical process for the method according to the invention comprises, for example, the following work stages:
  • 1. Degreasing: Strongly alkaline, aqueous immersion cleaner; aqueous spray cleaner, organic solvents;
  • 2. rinsing with water;
  • 3. Rust removal and descaling: Aqueous hydrochloric acid, sulfuric acid or phosphoric acid, possibly also blasting or grinding;
  • 4. rinsing with water;
  • 5. Pre-rinse: hot water, if necessary with the addition of activating agent;
  • 6. phosphating;
  • 7. Rinse with water;
  • 8. Passivating rinse: aqueous rinse containing chromium (VI) -chrome (III);
  • 9. drying (if desired);
  • 10. Impregnation with cationic synthetic resin: pigmented solution / emulsion of a cationic, modified synthetic resin; Solids content: 25%; 25 ° C; 1 min diving, then air drying; diving again for 1 min;
  • 11. Hardening of the impregnation film: baking for 20 min at 185 ° C object temperature.

Die unter 1. genannte Entfettung bzw. die Entrostung und Entzunderung gemäß 3. können entfallen, wenn die zu behandelnden Teile fettfrei bzw. rost- oder zunderfrei sind.Degreasing or referred to in the first e ntrostung and descaling according to the third may be omitted if the parts to be treated are free of grease or rust or scale-free.

Nach vorstehendem Arbeitsgang behandelte Stahlteile zeigen erst nach 800 bis 1000 Std. Salzsprühtest SS DIN 50021 beginnende Rostbildung. Wenn anstelle der kationischen Imprägnierung Rostschutzöle bzw. Rostschutzwachse auf die genannten Phosphatschichten aufgebracht werden, ist erste Rostbildung je nach verwendetem Rostschutzmittel nach 80 bis 500 Std. zu beobachten.Steel parts treated according to the above operation show rust formation only after 800 to 1000 hours. Salt spray test SS DIN 50021. If ostschutzöle instead of the cationic impregnation R or rustproofing waxes are applied to the said phosphate layers, first rust formation is observed, depending on the rust inhibitor of 80 to 500 h..

Claims (6)

1. Verfahren zum Korrosionsschutz von Metallen, insbesondere von Eisen und Stahl, durch Aufbringen einer Phosphatschicht und Imprägnieren der Phosphatschicht mit organischem Kunstharz, dadurch gekennzeichnet, daß man auf der Metalloberfläche zunächst eine Phosphatschicht mit einem Flächengewicht von mindestens 8 g/m2 erzeugt und mittels einer wäßrigen Lösung oder Dispersion eines kationischen Kunstharzes stromlos mindestens 8 g/m2 Kunstharz aufbringt und einbrennt.1. A method for corrosion protection of metals, in particular iron and steel, by applying a phosphate layer and impregnating the phosphate layer with organic synthetic resin, characterized in that a phosphate layer with a basis weight of at least 8 g / m 2 is first produced on the metal surface and by means of in an aqueous solution or dispersion of a cationic synthetic resin, at least 8 g / m 2 synthetic resin is electrolessly applied and stoved. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man maximal 40 g/m2 Kunstharz aufbringt und einbrennt.2. The method according to claim 1, characterized in that a maximum of 40 g / m 2 synthetic resin is applied and baked. 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß man das kationische Kunstharz aus einer wäßrigen Lösung oder Dispersion aufbringt, die zusätzlich aus der Lack- und Farbformulierung bekannte Zusätze und Modifizierungsmittel, wie Farb-, Füll- und/oder Korrosionsschutzpigmente, lösliche Korrosionsinhibitoren, organische Lösungsmittel und/oder Additive für einen verbesserten Filmverlauf sowie zur Unterstützung des Vernetzungsvorganges beim Einbrennen enthält.3. The method of claim 1 or 2, characterized in that applying the cationic resin from an aqueous solution or dispersion which additionally orrosionsschutzpigmente from the coatings and F arbformulierung known additives and modifiers such as dyes, fillers and / or K containing soluble corrosion inhibitors, organic solvents and / or additives for improved F ilmverlauf and to support the cross-linking process during baking. 4. Verfahren nach Anspruch 1, 2 oder 3, dadurch gekennzeichnet, daß man das kationische Kunstharz durch mindestens zweimaliges Benetzen mit kurzzeitigem Zwischentrocknen und abschließendem Einbrennen aufbringt.4. The method according to claim 1, 2 or 3, characterized in that the cationic synthetic resin by wetting at least twice with brief drying and then baking. 5. Verfahren nach einem oder mehreren der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß man die Phosphatschicht vor dem Aufbringen des kationischen Kunstharzes mit einem Cr-(VI)haltigen wäßrigen Passiviermittel behandelt.5. The method according to one or more of claims 1 to 4, characterized in that the phosphate layer is treated with a Cr (VI) -containing aqueous passivating agent before the application of the cationic synthetic resin. 6. Verfahren nach einem oder mehreren der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß man im Anschluß an das Einbrennen des kationischen Kunstharzes eine Nachbehandlung mit Korrosionsschutzöl durchführt.6. The method according to one or more of claims 1 to 5, characterized in that one carries out an aftertreatment with anti-corrosion oil after the stoving of the cationic synthetic resin.
EP84200397A 1983-04-26 1984-03-20 Process for the corrosion protection of metals Expired EP0126498B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3315019 1983-04-24
DE19833315019 DE3315019A1 (en) 1983-04-26 1983-04-26 METHOD FOR CORROSION PROTECTION OF METALS

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EP0126498A1 true EP0126498A1 (en) 1984-11-28
EP0126498B1 EP0126498B1 (en) 1987-06-16

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AU (1) AU2713784A (en)
BR (1) BR8401870A (en)
DE (2) DE3315019A1 (en)
ES (1) ES531122A0 (en)
GB (1) GB2138703B (en)
PT (1) PT78408B (en)
ZA (1) ZA843025B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0537697A1 (en) * 1991-10-17 1993-04-21 Herberts Gesellschaft mit beschränkter Haftung Process for making multilayer coating with a cationic filling-layer
EP0538719A1 (en) * 1991-10-17 1993-04-28 Herberts Gesellschaft mit beschränkter Haftung Process for making multilayers coating

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US5693739A (en) * 1995-12-21 1997-12-02 Ppg Industries, Inc. Phenolic polymers from amino phenols and anhydride or epoxy polymers
FR2818572B1 (en) † 2000-12-22 2003-03-14 Valeo METHOD FOR MANUFACTURING A GEARBOX SYNCHRONIZATION RING, PARTICULARLY FOR A MOTOR VEHICLE

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DE2432593A1 (en) * 1974-07-06 1976-01-22 Nippon Paint Co Ltd Duplex org.-inorg. coating in conducting materials - surface being covered with inorg. coating over which coating is applied by electrophoresis
CH595459A5 (en) * 1973-03-19 1978-02-15 Zbrojovka Brno Np Polyphenylene oxide protective coatings for metals
EP0091166A1 (en) * 1982-04-07 1983-10-12 Metallgesellschaft Ag Process for treating metal surfaces

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CH595459A5 (en) * 1973-03-19 1978-02-15 Zbrojovka Brno Np Polyphenylene oxide protective coatings for metals
DE2432593A1 (en) * 1974-07-06 1976-01-22 Nippon Paint Co Ltd Duplex org.-inorg. coating in conducting materials - surface being covered with inorg. coating over which coating is applied by electrophoresis
EP0091166A1 (en) * 1982-04-07 1983-10-12 Metallgesellschaft Ag Process for treating metal surfaces

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0537697A1 (en) * 1991-10-17 1993-04-21 Herberts Gesellschaft mit beschränkter Haftung Process for making multilayer coating with a cationic filling-layer
EP0538719A1 (en) * 1991-10-17 1993-04-28 Herberts Gesellschaft mit beschränkter Haftung Process for making multilayers coating
US5552227A (en) * 1991-10-17 1996-09-03 Herberts Gmbh Process of producing multilayer coatings with cationic layers of primer surface

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BR8401870A (en) 1984-11-27
EP0126498B1 (en) 1987-06-16
ES8506817A1 (en) 1985-08-01
DE3464261D1 (en) 1987-07-23
DE3315019A1 (en) 1984-10-31
GB8410725D0 (en) 1984-05-31
PT78408B (en) 1986-05-28
JPS59205481A (en) 1984-11-21
GB2138703A (en) 1984-10-31
GB2138703B (en) 1986-04-30
ZA843025B (en) 1985-06-26
AU2713784A (en) 1984-11-01
PT78408A (en) 1984-05-01
ES531122A0 (en) 1985-08-01

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