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EP0015021B1 - Process for the pretreatment of metal surfaces for electrophoretic dip painting - Google Patents

Process for the pretreatment of metal surfaces for electrophoretic dip painting Download PDF

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Publication number
EP0015021B1
EP0015021B1 EP80200097A EP80200097A EP0015021B1 EP 0015021 B1 EP0015021 B1 EP 0015021B1 EP 80200097 A EP80200097 A EP 80200097A EP 80200097 A EP80200097 A EP 80200097A EP 0015021 B1 EP0015021 B1 EP 0015021B1
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Prior art keywords
solutions
metal surfaces
ions
brought
contact
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Expired
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EP80200097A
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German (de)
French (fr)
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EP0015021A1 (en
Inventor
Werner Dr. Rausch
Gerhard Müller
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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Publication of EP0015021A1 publication Critical patent/EP0015021A1/en
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    • CCHEMISTRY; METALLURGY
    • C23COATING 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
    • C23CCOATING 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
    • C23C22/00Chemical 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
    • C23C22/05Chemical 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
    • C23C22/06Chemical 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
    • C23C22/34Chemical 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
    • C23C22/36Chemical 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 containing also phosphates
    • C23C22/362Chemical 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 containing also phosphates containing also zinc cations
    • CCHEMISTRY; METALLURGY
    • C23COATING 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
    • C23CCOATING 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
    • C23C22/00Chemical 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
    • C23C22/05Chemical 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
    • C23C22/06Chemical 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
    • C23C22/34Chemical 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
    • C23C22/36Chemical 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 containing also phosphates
    • CCHEMISTRY; METALLURGY
    • C23COATING 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
    • C23CCOATING 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
    • C23C22/00Chemical 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
    • C23C22/05Chemical 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
    • C23C22/06Chemical 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
    • C23C22/40Chemical 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 molybdates, tungstates or vanadates
    • C23C22/44Chemical 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 molybdates, tungstates or vanadates containing also fluorides or complex fluorides

Definitions

  • aqueous phosphating solutions are used for the treatment of surfaces made of ferrous metals and zinc, the essential constituents of which contain phosphate ions, zinc ions, cobalt, copper or nickel ions, magnesium ions, nitrite ions, fluorine and / or chlorine ions and optionally nitrate ions (DE -OS 2 049 350).
  • the solutions have contents of 3 to 20 g phosphate ions, 0.5 to 3 g zinc ions, 0.003 to 0.7 g cobalt ions or 0.003 to 0.04 g copper ions or preferably 0.05 to 3 g nickel ions, 1 to 8 g magnesium ions, 0.01 to 0.25 g of nitrite ions and 0.1 to 3 g of fluorine ions and / or 2 to 30 g of chlorine ions and optionally up to about 40 g of nitrate ions.
  • One of the ways of introducing the fluorine ions can be in the form of fluorosilicate or fluoroborate ions.
  • Paint or other fast-drying organic coatings can then be applied to the phosphate layers produced in this way.
  • a disadvantage of the coatings produced with the known solutions based on zinc phosphate or magnesium and / or calcium phosphate as the basis for the subsequent electrodeposition coating is in particular that a considerable part of the phosphate coating is separated off during the coating process, passes into the coating film and adversely affects it .
  • Essentially free of ferroions means that the treatment of non-ferrous metals does not involve the use of bath solutions that contain substantial amounts of ferroions, and the preferred treatment of steel surfaces brings them into contact with solutions that contain accelerators that oxidize ferroions.
  • Treatment solutions containing chlorate and / or nitrite are particularly suitable. It is sufficient to use as much chlorate and / or nitrite as is necessary to remove excess ferroions by oxidation. The amounts are thus dependent on the throughput and do not need to be specifically matched to the amount of zinc ions and phosphoric acid or to phosphoric acid, as is required in known processes. However, it has been found that the chlorate content should be set to at least 0.1 g / l. Larger quantities are advisable for high throughputs.
  • Solutions are advantageously used which contain vanadium compounds, preferably in amounts of 0.1 to 10 mg / l vanadium, which has proven to be particularly advantageous at high throughputs.
  • Other polyvalent cations such as Ni, Mn or Ca ions, the amount of which, however, should not exceed 0.5 gll, bring about a further improvement.
  • alkali metal ions Na, NH 4 etc.
  • the content of P0 4 is in the usual range and is about 5 to 20 g / l .
  • the phosphate layers achieved with the method according to the invention provide such a high level of corrosion protection (higher sub-walls protection) that a subsequent treatment with the known rinse agents, for. B. Cr (VI) - or Cr (III) ion-containing, practically no additional improvement.
  • the phosphate layers produced with the invention are of a quality that is otherwise only achieved by using additional rinsing agents.
  • the sheets were then rinsed with water and deionized water and then dried.
  • the layer weight achieved was 1.8 g / m 2 .
  • a modified epoxy resin varnish was then cathodically deposited on the steel sheet pretreated in this way.
  • the electrodeposition bath had room temperature, the deposition voltage and duration were 180 volts or 2 minutes.
  • the varnish was then baked at an object temperature of 190 ° C for 25 minutes.
  • the paint film thickness obtained was 15 ⁇ m, the paint layer was uniform and shiny.
  • the paint infiltration determined after the salt spray test was only less than 1 mm.

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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)

Description

Die Erfindung betrifft ein Verfahren zur Vorbereitung von Metalloberflächen, insbesondere aus Stahl, für die elektrophoretische Tauchlackierung durch Aufbringen von Phosphatschichten mittels Lösungen auf Basis Zinkphosphat mit einem Zusatz von Alkaliionen, in denen das Gewichtsverhältnis von Zn : P04 = I : (12 bis 110), vorzugsweise = 1 : ( 20 bis 100) ist.The invention relates to a method for preparing metal surfaces, in particular steel, for electrophoretic dip coating by applying phosphate layers by means of solutions based on zinc phosphate with the addition of alkali ions, in which the weight ratio of Zn: P0 4 = I: (12 to 110) , preferably = 1: (20 to 100).

Es ist seit langem üblich, Metalloberflächen durch Aufbringung eines Phosphatüberzuges für die anschliessende Lackierung vorzubereiten, um eine Verbesserung des Korrosionsschutzes und eine Erhöhung der Lackhaftung zu erzielen. Als Grundlage für die Elektrotauchlackierung dienen hauptsächlich Zinkphosphatüberzüge. Zu deren Erzeugung werden üblicherweise wässrige saure Überzugslösungen auf Basis Monozinkphosphat verwendet, denen Chlorat, Nitrit, Nitrat, organische Nitroverbindungen oder Gemische hiervon als Beschleuniger zugesetzt werden. Die erhaltenen Überzüge sind jedoch häufig für die anschliessende Lackierung wegen ihrer Dicke und Grobkristallinität unbefriedigend. Da zur Vorbehandlung vor der Elektrotauchlackierung dünne und feinkörnige Überzüge erwünscht sind, werden deshalb den Lösungen ausserdem häufig verschiedene organische oder anorganische Chelatierungsmittel, wie Zitronensäure, Weinsäure, Malonsäure, Polyphosphorsäure, Glycerophosphorsäure, Äthylendiamintetraessigsäure, Nitrilotriessigsäure oder deren Salze zugesetzt. Hierdurch ergeben sich jedoch häufig schwierigkeiten, die Lösungen zu kontrollieren; auch genügt die Schichtausbildung oft nicht den gestellten Anforderungen.It has long been customary to prepare metal surfaces by applying a phosphate coating for the subsequent painting in order to improve corrosion protection and increase paint adhesion. Mainly zinc phosphate coatings serve as the basis for electrocoating. To produce them, aqueous acidic coating solutions based on monozinc phosphate are usually used, to which chlorate, nitrite, nitrate, organic nitro compounds or mixtures thereof are added as accelerators. However, the coatings obtained are often unsatisfactory for the subsequent coating because of their thickness and coarse crystallinity. Since thin and fine-grained coatings are desired for the pretreatment before electrocoating, various organic or inorganic chelating agents, such as citric acid, tartaric acid, malonic acid, polyphosphoric acid, glycerophosphoric acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid or salts thereof, are therefore often added to the solutions. However, this often creates difficulties in controlling the solutions; the layer formation also often does not meet the requirements.

Bei einem weiteren Verfahren kommen wässrige Phosphatierungslösungen zur Behandlung von Oberflächen aus Eisenmetallen und Zink zur Anwendung, die als wesentliche Bestandteile Phosphationen, Zinkionen, Kobalt-, Kupfer- oder Nickelionen, Magnesiumionen, Nitritionen, Fluor-und/oder Chlorionen sowie gegebenenfalls Nitrationen enthalten (DE-OS 2 049 350). Die Lösungen weisen Gehalte von 3 bis 20 g Phosphationen, 0,5 bis 3 g Zinkionen, 0,003 bis 0,7 g Kobaltionen oder 0,003 bis 0,04 g Kupferionen oder vorzugsweise 0,05 bis 3 g Nickelionen, 1 bis 8 g Magnesiumionen, 0,01 bis 0,25 g Nitritionen und 0,1 bis 3 g Fluorionen und/oder 2 bis 30 g Chlorionen sowie gegebenenfalls bis etwa 40 g Nitrationen auf. Eine der Möglichkeiten der Einbringung der Fluorionen kann in Form von Fluorosilikat- oder Fluoroborationen erfolgen.In a further process, aqueous phosphating solutions are used for the treatment of surfaces made of ferrous metals and zinc, the essential constituents of which contain phosphate ions, zinc ions, cobalt, copper or nickel ions, magnesium ions, nitrite ions, fluorine and / or chlorine ions and optionally nitrate ions (DE -OS 2 049 350). The solutions have contents of 3 to 20 g phosphate ions, 0.5 to 3 g zinc ions, 0.003 to 0.7 g cobalt ions or 0.003 to 0.04 g copper ions or preferably 0.05 to 3 g nickel ions, 1 to 8 g magnesium ions, 0.01 to 0.25 g of nitrite ions and 0.1 to 3 g of fluorine ions and / or 2 to 30 g of chlorine ions and optionally up to about 40 g of nitrate ions. One of the ways of introducing the fluorine ions can be in the form of fluorosilicate or fluoroborate ions.

Auf diese so erzeugten Phosphatschichten können anschliessend Anstrichfarben oder andere schnelltrocknende organische Überzüge aufgebracht werden.Paint or other fast-drying organic coatings can then be applied to the phosphate layers produced in this way.

Ein Nachteil der mit den bekannten Lösungen auf Basis Zinkphosphat bzw. Magnesium- und/ oder Kalziumphosphat erzeugten Überzüge als Grundlage für die anschliessende Elektrotauchlackierung besteht insbesondere darin, dass ein beachtlicher Teil des Phosphatüberzuges bei der Lackierung abgetrennt wird, in den Lackfilm übergeht und diesen nachteilig beeinflusst.A disadvantage of the coatings produced with the known solutions based on zinc phosphate or magnesium and / or calcium phosphate as the basis for the subsequent electrodeposition coating is in particular that a considerable part of the phosphate coating is separated off during the coating process, passes into the coating film and adversely affects it .

Zwar ist es bekannt, diese Nachteile weitgehend zu vermeiden, indem man Behandlungslösungen zum Einsatz bringt, in denen der Zinkanteil in Bezug auf die Phosphationen gegenüber den üblichen Lösungen auf Basis Monozinkphosphat erheblich erniedrigt ist (DE-OS 2232067). Die Behandlung führt zu verbesserten dünnen und gleichmässigen Phosphatüberzügen auf Metalloberflächen, insbesondere Stahl, die sehr haftfest und beständig und als Grundlage für die anschliessende Elektrotauchlackierung geeignet sind. Die Phosphatschichten vermitteln einen hohen Korrosionsschutz und werden bei der Lackierung zu einem wesentlich geringeren Anteil abgetrennt als die bei Verwendung der bisher üblichen Lösungen erzeugten Überzüge.It is known to largely avoid these disadvantages by using treatment solutions in which the zinc content in relation to the phosphate ions is considerably reduced compared to the conventional solutions based on monozinc phosphate (DE-OS 2232067). The treatment leads to improved thin and uniform phosphate coatings on metal surfaces, especially steel, which are very adhesive and resistant and are suitable as a basis for the subsequent electrocoating. The phosphate layers provide a high level of protection against corrosion and are removed to a much lesser extent during painting than the coatings produced when using the solutions customary hitherto.

Es wurde nun gefunden, dass die mit dem Verfahren gemäss DE-OS 2 232 067 erzielten Vorteile noch vermehrt werden können, wenn man das eingangs genannte Verfahren entsprechend der Erfindung derart ausstattet, dass die Metalloberflächen mit Lösungen in Berührung gebracht werden, die zusätzlich einen Gehalt an Fluoborat, vorzugsweise in Mengen von 0,3 bis 2,0 g/I, aufweisen und im wesentlichen ferroionenfrei sind.It has now been found that the advantages achieved with the method according to DE-OS 2 232 067 can be increased further if the method mentioned at the outset according to the invention is equipped in such a way that the metal surfaces are brought into contact with solutions which additionally contain of fluoborate, preferably in amounts of 0.3 to 2.0 g / l, and are essentially free of ferroions.

Im wesentlichen Ferroionenfrei bedeutet, dass man bei der Behandlung von Nichteisenmetallen von der Verwendung von Badlösungen absieht, die wesentliche Ferroionenmengen enthalten und bei der vorzugsweise vorgesehenen Behandlung von Stahloberflächen, diese mit Lösungen in Berührung bringt, die Ferro- zu Ferriionen oxydierende Beschleuniger enthalten.Essentially free of ferroions means that the treatment of non-ferrous metals does not involve the use of bath solutions that contain substantial amounts of ferroions, and the preferred treatment of steel surfaces brings them into contact with solutions that contain accelerators that oxidize ferroions.

Besonders geeignet sind Behandlungslösungen, die Chlorat und/oder Nitrit enthalten. Dabei ist es ausreichend, soviel Chlorat und/oder Nitrit zu verwenden, als zur Entfernung von überschüssigen Ferroionen durch Oxidation notwendig sind. Die Mengen sind also vom Durchsatz abhängig und brauchen nicht besonders auf die Menge an Zinkionen und Phosphorsäure oder auf Phosphorsäure abgestimmt zu werden, wie dies bei bekannten Verfahren vorgeschrieben ist. Es hat sich jedoch erwiesen, dass der Gehalt an Chlorat auf mindestens 0,1 g/I eingestellt werden sollte. Bei hohen Durchsätzen sind grössere Mengen zweckmässig.Treatment solutions containing chlorate and / or nitrite are particularly suitable. It is sufficient to use as much chlorate and / or nitrite as is necessary to remove excess ferroions by oxidation. The amounts are thus dependent on the throughput and do not need to be specifically matched to the amount of zinc ions and phosphoric acid or to phosphoric acid, as is required in known processes. However, it has been found that the chlorate content should be set to at least 0.1 g / l. Larger quantities are advisable for high throughputs.

Vorteilhafterweise gelangen Lösungen zum Einsatz, die Vanadin-Verbindungen, vorzugsweise in Mengen von 0,1 bis 10 mg/I Vanadin, enthalten, was sich besonders bei hohen Durchsätzen als vorteilhaft erwiesen hat. Weitere mehrwertige Kationen, wie Ni-, Mn- oder Ca-Ionen, deren Menge jedoch höchstens 0,5 gll betragen soll, bewirken eine weitere Verbesserung.Solutions are advantageously used which contain vanadium compounds, preferably in amounts of 0.1 to 10 mg / l vanadium, which has proven to be particularly advantageous at high throughputs. Other polyvalent cations, such as Ni, Mn or Ca ions, the amount of which, however, should not exceed 0.5 gll, bring about a further improvement.

Um den Anteil an PO" der den erforderlichen Grad freier Säure übersteigt, zu binden, ist ein Zusatz von Alkalimetallionen (Na, NH4 usw.) erforderlich. Der Gehalt an P04 liegt im üblichen Bereich und beträgt etwa 5 bis 20 g/I.In order to bind the proportion of PO "which exceeds the required degree of free acid, an addition of alkali metal ions (Na, NH 4 etc.) is required. The content of P0 4 is in the usual range and is about 5 to 20 g / l .

Die mit dem erfindungsgemässen Verfahren erzielten Phosphatschichten vermitteln einen so hohen Korrosionsschutz (höherer Unterwanderungsschutz), dass eine Folgebehandlung mit den bekannten Nachspülmitteln, z. B. Cr(VI)- oder Cr(III)-lonen-haltig, praktisch keine zusätzliche Verbesserung bewirkt. Das heisst, die mit der Erfindung erzeugten Phosphatschichten sind von einer Qualität, die sonst nur durch Verwendung zusätzlicher Nachspülmittel erzielt wird.The phosphate layers achieved with the method according to the invention provide such a high level of corrosion protection (higher sub-walls protection) that a subsequent treatment with the known rinse agents, for. B. Cr (VI) - or Cr (III) ion-containing, practically no additional improvement. This means that the phosphate layers produced with the invention are of a quality that is otherwise only achieved by using additional rinsing agents.

AusführungsbeispielEmbodiment

a) Entfettete Stahlbleche werden innerhalb von 2 Minuten durch Spritzen mit einer Phosphatierungslösung von 58°C behandelt, die

Figure imgb0001
enthielt. Der Wert für freie Säure lag bei 0,8, für Gesamtsäure bei 14,5.a) Degreased steel sheets are treated within 2 minutes by spraying with a phosphating solution of 58 ° C, the
Figure imgb0001
contained. The value for free acid was 0.8 and for total acid 14.5.

Die Bleche wurden dann mit Wasser und mit vollentsalztem Wasser gespült und anschliessend getrocknet.The sheets were then rinsed with water and deionized water and then dried.

Das erzielte Schichtgewicht betrug 1,8 g/m2.The layer weight achieved was 1.8 g / m 2 .

Anschliessend wurde auf dem so vorbehandelten Stahlblech ein modifizierter Epoxyharzlack kathodisch abgeschieden. Das Bad für die Elektrotauchlackierung besass Raumtemperatur, Abscheidespannung und -dauer lagen bei 180 Volt bzw. 2 Minuten. Danach wurde der Lack bei einer Objekttemperatur von 190°C während 25 Minuten eingebrannt. Die dabei erhaltene Lackfilmdicke war 15 µm, die Lackschicht gleichmässig und glänzend.A modified epoxy resin varnish was then cathodically deposited on the steel sheet pretreated in this way. The electrodeposition bath had room temperature, the deposition voltage and duration were 180 volts or 2 minutes. The varnish was then baked at an object temperature of 190 ° C for 25 minutes. The paint film thickness obtained was 15 μm, the paint layer was uniform and shiny.

Der Korrosionsschutz der mit dem Lack versehenen und kreuzweise eingeritzten Blechs wurde im Salzsprühtest (1000 Std.) geprüft. Die danach ermittelte Lackunterwanderung betrug 1 bis 2 mm.The corrosion protection of the sheet, which had been lacquered and scratched crosswise, was tested in a salt spray test (1000 hours). The paint infiltration determined after this was 1 to 2 mm.

b) Der vorstehend skizzierte Verfahrensgang wurde in allen Einzelheiten wiederholt. Es kam jedoch eine Phosphatierungslösung zur Anwendung, die neben den unter a) aufgeführten Bestandteilen zusätzlich

Figure imgb0002
enthielt.b) The procedure outlined above was repeated in every detail. However, a phosphating solution was used, which in addition to the components listed under a)
Figure imgb0002
contained.

Die nach dem Salzsprühtest ermittelte Lackunterwanderung lag nur bei kleiner 1 mm.The paint infiltration determined after the salt spray test was only less than 1 mm.

c) Der Behandlungsgang gemäss b) wurde dahingehend variiert, dass anstelle der Spülung mit Wasser einmal mit Chrom(III)-acetat-Lösung (150 mg/I Cr(III)) und einmal mit Chromsäure/ Chrom(III)-acetat-Lösung (150 mg/1 Cr(VI), 40 mg/I Cr(III)) gespült wurde.c) The course of treatment according to b) was varied such that instead of rinsing with water once with chromium (III) acetate solution (150 mg / l Cr (III)) and once with chromic acid / chromium (III) acetate solution (150 mg / 1 Cr (VI), 40 mg / I Cr (III)) was rinsed.

Der nach der Lackierung etc. vorgenommene Salzsprühtest brachte die gleichen Ergebnisse wie unter b).The salt spray test carried out after painting, etc. gave the same results as under b).

Ein Vergleich der Ergebnisse zeigt, dass der Korrosionsschutz, speziell der Lackunterwanderungsschutz, der mit Fluoborat modifizierten Phosphatierungslösung erheblich besser ist als der, der bei Verwendung einer Fluoboratfreien Phosphatierungslösung erhalten wird. Ausserdem ist erkennbar, dass auch ohne Nachspülung mit Cr(III)-bzw. Cr(VI)-Lösungen ein Korrosionsschutz erzielt wird, der dem mit Verwendung der genannten Lösung praktisch gleich ist.A comparison of the results shows that the corrosion protection, in particular the paint infiltration protection, of the phosphating solution modified with fluoroborate is considerably better than that which is obtained when using a fluoroborate-free phosphating solution. In addition, it can be seen that even without rinsing with Cr (III) or. Cor (VI) solutions a corrosion protection is achieved, which is practically the same as using the solution mentioned.

Claims (7)

1. Process for the pretreatment of metal surfaces for electrophoretic dip painting by application of phosphate coatings by means of solutions on the basis of zinc phosphate with an addition of alkali metal ions, in which the weight ratio of Zn : PO4 is 1 : (12 to 110), characterized in that the metal surfaces are brought in contact with solutions, which contain additionally fluoborate and are substantially free of ferrous ions.
2. Process according to claim 1, characterized in that the metal surfaces are brought in contact with solutions, which contain chlorate and/or nitrite as accelerator.
3. Process according to claim 1 or 2, characterized in that the metal surfaces are brought in contact with solutions, which contain vanadium compounds in amounts of 0,1 to 10 mg/I.
4. Process according to claim 1, 2 or 3, characterized in that the metal surfaces are brought in contact with solutions, in which the weight ratio of Zn : PO, is 1 : (20 to 100).
5. Process according to claim 1, 2, 3 or 4, characterized in that the metal surfaces are brought in contact with solutions, which contain fluoborate in amounts of 0,3 to 2,0 g/J.
6. Use of the process according to one or more of the claims 1 to 5 for the treatment of steel surfaces.
7. Use according to claim 6, wherein steel surfaces are brought in contact with solutions, which contain accelerators oxidizing ferrous to ferric ions.
EP80200097A 1979-02-23 1980-02-05 Process for the pretreatment of metal surfaces for electrophoretic dip painting Expired EP0015021B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2907094 1979-02-23
DE19792907094 DE2907094A1 (en) 1979-02-23 1979-02-23 PHOSPHATION SOLUTIONS

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EP0015021A1 EP0015021A1 (en) 1980-09-03
EP0015021B1 true EP0015021B1 (en) 1984-10-03

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US (1) US4265677A (en)
EP (1) EP0015021B1 (en)
JP (1) JPS5914113B2 (en)
AU (1) AU531900B2 (en)
CA (1) CA1134246A (en)
DE (2) DE2907094A1 (en)
ES (1) ES8200408A2 (en)
GB (1) GB2046312A (en)
IT (1) IT1141231B (en)
ZA (1) ZA80915B (en)

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JPS5811515B2 (en) * 1979-05-11 1983-03-03 日本ペイント株式会社 Composition for forming a zinc phosphate film on metal surfaces
US4330345A (en) * 1980-12-08 1982-05-18 Chemfil Corporation Phosphate coating process and composition
DE3101866A1 (en) * 1981-01-22 1982-08-26 Metallgesellschaft Ag, 6000 Frankfurt METHOD FOR PHOSPHATING METALS
DE3118375A1 (en) * 1981-05-09 1982-11-25 Metallgesellschaft Ag, 6000 Frankfurt METHOD FOR PHOSPHATING METALS AND ITS APPLICATION FOR PRE-TREATMENT FOR ELECTRO DIP PAINTING
JPS58224172A (en) * 1982-06-24 1983-12-26 Nippon Parkerizing Co Ltd Pretreatment for coating by cationic electrodeposition
US4681641A (en) * 1982-07-12 1987-07-21 Ford Motor Company Alkaline resistant phosphate conversion coatings
DE3244715A1 (en) * 1982-12-03 1984-06-07 Gerhard Collardin GmbH, 5000 Köln METHOD FOR PHOSPHATING METAL SURFACES, AND BATH SOLUTIONS SUITABLE FOR THIS
JPS59133375A (en) * 1983-12-03 1984-07-31 Nippon Paint Co Ltd Composition for forming zinc phosphate film on metallic surface
DE3408577A1 (en) * 1984-03-09 1985-09-12 Metallgesellschaft Ag, 6000 Frankfurt METHOD FOR PHOSPHATING METALS
DE3541997A1 (en) * 1985-11-28 1987-06-04 Collardin Gmbh Gerhard IMPROVED METHOD FOR ACTIVATING METAL SURFACES BEFORE ZINC PHOSPHATION
JPS63100185A (en) * 1986-10-16 1988-05-02 Nippon Parkerizing Co Ltd Phosphating method
DE3636390A1 (en) * 1986-10-25 1988-04-28 Metallgesellschaft Ag METHOD FOR PRODUCING PHOSPHATE COATINGS ON METALS
DE58905074D1 (en) * 1988-02-03 1993-09-09 Metallgesellschaft Ag METHOD FOR PRODUCING PHOSPHATE COATINGS ON METALS.
DE3814287A1 (en) * 1988-04-28 1989-11-09 Henkel Kgaa POLYMERS TITANIUM PHOSPHATES, METHOD FOR THE PRODUCTION THEREOF AND THEIR USE FOR ACTIVATING METAL SURFACES BEFORE ZINC PHOSPHATION
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AU5580480A (en) 1980-08-28
JPS5914113B2 (en) 1984-04-03
EP0015021A1 (en) 1980-09-03
ES488871A0 (en) 1981-11-01
JPS55131177A (en) 1980-10-11
IT1141231B (en) 1986-10-01
US4265677A (en) 1981-05-05
IT8020102A0 (en) 1980-02-22
CA1134246A (en) 1982-10-26
AU531900B2 (en) 1983-09-08
ES8200408A2 (en) 1981-11-01
DE2907094A1 (en) 1980-09-04
ZA80915B (en) 1981-02-25
DE3069330D1 (en) 1984-11-08
GB2046312A (en) 1980-11-12

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