Two-stage method for the corrosion protection treatment of metal surfaces

Patent metadata

Field	Value
Publication number	US-9403188-B2
Application number	US-201213409824-A
Country	US
Kind code	B2
Filing date	Mar 1, 2012
Priority date	Sep 10, 2009
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

The invention relates to an at least two-stage method for corrosion protection treatment of metal surfaces, wherein, in a first step (i), an organic coating comprising an aqueous phase (A) is applied to the metal surface and, in a following step (ii), the organic coating applied to the metal surface contacted with an acidic, aqueous composition (B) comprising at least one or more water-soluble compounds containing at least one atom selected from the elements Zr, Ti, Si, Hf, V and/or Ce and one or more water-soluble compounds that release copper ions. The invention further comprises a metal component that is at least partially made of steel, iron, zinc and/or aluminum and the alloys thereof and has been treated by the method according to the invention, and to the use thereof in automobile construction and in the construction industry and for producing household appliances and electronics housings.

First claim

What is claimed is:

1. A method for corrosion-protective treatment of metal surfaces, comprising: in a first step (i) applying an organic coating made up of an aqueous phase (A) onto the metal surface, wherein the metal surface having the organic coating is, in a subsequent step (ii), brought into contact with an acidic aqueous composition (B) that comprises at least
a) one or more water-soluble compounds containing at least one atom selected from the elements Zr, Ti, Si, Hf, V, and Ce, and
b) one or more water-soluble compounds that release copper ions;
wherein the acidic aqueous composition (B) contains no more than 1 ppm soluble phosphates.

2. The method according to claim 1 , wherein application of the organic coating in the first step (i) occurs in electroless fashion.

3. The method according to claim 2 , wherein in the first step (i), the aqueous phase (A) has a pH of less than 4 and contains
a) at least one dispersed organic binding agent system that is thermally curable, at temperatures below 300° C.,
b) iron(III) ions, and
c) fluoride ions in a quantitative proportion such that the molar ratio of fluoride ions to iron(III) ions from water-soluble compounds is equal to at least 2:1.

4. The method according claim 1 , wherein in the subsequent step (ii), the acidic aqueous composition (B) has a pH of 2 to 5, and comprises:
a) at least a total of 100 ppm, but no more than 2000 ppm, water-soluble compounds containing at least one atom selected from the elements Zr, Ti, Si, Hf, V, and Ce, calculated as a proportion of the respective element, and
b) at least 1 ppm, but no more than 100 ppm, water-soluble compounds that release copper ions, calculated as a proportion of copper;
wherein (B) further comprises a depolarizer which suppresses formation of nascent hydrogen at bare metal surfaces during the subsequent step (ii).

5. The method according claim 4 , wherein the depolarizer is selected from chlorate ions, nitrite ions, hydroxylamine, hydrogen peroxide in free or bound form, m-nitrobenzenesulfonate ions, m-nitrobenzoate ions, p-nitrophenol, N-methylmorpholine-N-oxide, nitroguanidine and mixtures thereof.

6. The method according claim 4 , wherein in the subsequent step (ii), the acidic aqueous composition (B) has no more than 800 ppm of the water-soluble compounds containing at least one atom selected from the elements Zr, Ti, and/or Si, calculated as a proportion of the respective element; and the acidic aqueous composition (B) contains no soluble phosphates.

7. The method according claim 1 , wherein the acidic aqueous composition (B) comprises fluoride ions in an amount such that measured free fluoride is at least 1 ppm and not higher than 400 ppm.

8. The method according claim 1 , wherein in the acidic aqueous composition (B), the one or more water-soluble compounds a) comprise Zr, and V or Ce.

9. The method according claim 1 , wherein in the first step (i), the organic binding agent system dispersed in the aqueous phase (A) has a film formation temperature of no more than 80° C. and in the subsequent step (ii), the acidic aqueous composition (B) is brought, at a temperature of at least 30° C., but no more than 80° C., into contact with the metal surface having the organic coating.

10. The method according claim 3 , wherein after method step (ii) and with or without an interposed rinsing step to remove components of the acidic aqueous composition (B) from the treated metal surface, the organic coating of the metal surface is cured at temperatures above a curing temperature of the at least one dispersed organic binding agent system that is thermally curable and below 300° C.

11. The method according claim 1 , wherein the metal surface is produced at least partly from steel, iron, zinc, and/or aluminum and, before the method step (i), is subjected to a conversion treatment comprising contacting bare metal surfaces and acidic aqueous solutions that comprise one or more water-soluble compounds of elements selected from Zr, Ti, Si, Hf, V, Ce, Mo, Zn, Mn, Fe, during which an inorganic covering layer forms having a layer weight per unit area of the inorganic covering layer of no more than 3 g/m 2 .

12. The method according claim 1 , wherein the metal surface is steel, iron, zinc, and/or aluminum; composition (B) comprises 400 to 1200 ppm Zr and 1 to 100 ppm Cu; and the dispersed organic binding agent system comprises a hardener selected from isocyanate resin and phenolic resin.

13. The method according claim 1 , wherein after step (ii), the metal surface having the organic coating and the acidic aqueous composition (B) thereon is rinsed.

Assignees

• Rosenkranz Christian
• Arnold Andreas
• Lepa Klaus
• Markou Konstantinos
• Henkel Ag & Co Kgaa

Inventors

• Rosenkranz Christian
• Arnold Andreas
• Lepa Klaus
• Markou Konstantinos

Classifications

• C23C22/78

  Pretreatment of the material to be coated · CPC title

• B05D5/00 Primary

  Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures · CPC title

• C23C22/34

  containing fluorides or complex fluorides · CPC title

• B05D3/107

  Post-treatment of applied coatings · CPC title

• B05D2202/00

  Metallic substrate · CPC title