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Chemical conversion solution for metal structure and surface treating method

a chemical conversion solution and metal structure technology, applied in electrophoretic coatings, solid-state diffusion coatings, coatings, etc., can solve the problems of insufficient throwing power during electrodeposition, insufficient environmental point of view, and damage to human body, etc., to achieve high coating adhesion of metal surfaces, high throwing power, and corrosion resistance.

Inactive Publication Date: 2011-04-28
HENKEL KGAA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0086]The present invention is an attempt to solve the problems of the prior art as described above, and in particular, the present invention provides a chemical conversion solution and the surface treating method for realizing high corrosion resistance and high coating adhesion of the metal surface, as well as high throwing power during electrodeposition. More specifically, the present invention provides a chemical conversion solution and a surface treating method for a metal structure which is capable of realizing high throwing power during the electrodeposition of the level equal to or higher than the case using a phosphate without drying the pretreated metal structure particularly when applied to an automobile body or its part, which provides adequate corrosion resistance and coating adhesion to the metal structure, which is also capable of controlling and reducing the industrial wastes such as sludge in the commercial scale production, and which is economical and inexpensive.
[0087]The inventors of the present invention made an extensive investigation on the measures to solve the problems of the prior art as described above, and found that throwing power during the electrodeposition can be greatly improved by depositing a germanium compound, a tin compound and / or a copper compound on the surface of the metal structure, and as a consequence, arrived at a new finding that the throwing power during the electrodeposition can be controlled by means of the underlying film. The inventors of the present invention also found that an even higher corrosion resistance and coating adhesion can be realized when the germanium compound, the tin compound and / or the copper compound is deposited on the metal structure simultaneously with the conventional titanium compound and / or zirconium compound to form a composite film. The present invention has been completed on the bases of such findings.
[0119]The chemical conversion solution and the surface treating method for a metal structure of the present invention are capable of realizing high corrosion resistance as well as high coating adhesion of the metal surface without using the harmful hexavalent chromium. The chemical conversion solution and the surface treating method for a metal structure of the present invention are also capable of realizing high throwing power during electrodeposition on a complicated structure as in the case of, for example, a transportation vehicle, namely, an automobile. The chemical conversion solution and the surface treatment and the surface treating method of the present invention are also capable of controlling and reducing the industrial wastes such as sludge in the commercial scale production.

Problems solved by technology

However, since it etches the steel material, iron dissolves as a byproduct of the chemical conversion reaction.
As described above, insufficient throwing power during the electrodeposition has been a serious problem in the case of complicated structure such as automobile body.
Of these proposals, the use of the trivalent chromium solution (5) will leave trivalent chromium in the resulting film, and when this film is exposed to a high temperature, the trivalent chromium will turn into the hexavalent chromium which is harmful to the human body.
Accordingly, this technique is inadequate in environmental point of view.
However, this surface treatment (6) is unable to form a consistent film when used for a complicated structure as in the case of an automobile body due to the formation of the liquid pool.
These requirements are not fully overcome.
However, this solution does not dramatically improve the corrosion resistance, and as in the case of other solutions as described above, throwing power during the electrodeposition is not sufficient when used for transportation vehicles such as automobile.
However, these solutions are far from perfect in terms of the throwing power during the electrodeposition in the case of the metal structure of transportation vehicles such as automobile.
When the film produced by the example of JP 2008-88551A was compared with the conventional phosphate film, the results were not necessarily satisfactory.
This invention, however, includes a step requiring hot air heater or hot water, and when carried out in commercial scale, it leads to an unfavorable increase in the cost and complication.
Hence, this method is not practical.
This invention, however, requires a post treatment after the chemical conversion, and when carried out in commercial scale, it leads to an unfavorable increase in the cost and complication.
Hence, this method is not practical.
As described above, the chemical conversion film formed by applying conventional non-chromate type surface treating solution to the transportation vehicle metal structure such as a automobile metal structure had various problems such as the insufficient corrosion resistance and coating adhesion.

Method used

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  • Chemical conversion solution for metal structure and surface treating method
  • Chemical conversion solution for metal structure and surface treating method
  • Chemical conversion solution for metal structure and surface treating method

Examples

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Effect test

example 1

[0157]Chemical conversion solution 1 having the following composition was prepared, and surface treatment of the three types of the metal plate and the box as described below was conducted by the surface treating method (1) to form a chemical conversion film. The chemical conversion solution 1 was prepared by adding the following components (A) to (F) to 80% of the total content of water in the order of (F), (A), (B), (D), and (E), finally adding water to the predetermined volume, and stirring at room temperature for 20 minutes. The solution was heated to the predetermined temperature, and pH was adjusted. The surface treated metal plate was rinsed with water, and then with deionized water, and without drying, the metal plate was subjected to the electrodeposition by using the procedure and conditions as described above to thereby form the coating.

[0158]Chemical Conversion Solution 1

[0159](A): tin fluoride, 0.2 mmol / L

[0160](B): fluorotitanic acid, 3 mmol / L

[0161](C): nitrate radical ...

example 2

[0174]Chemical conversion solution 2 having the following composition was prepared, and surface treatment of the three types of the metal plate and the box was conducted by the surface treating method (3). The chemical conversion solution was prepared by adding the following components (A) to (F) to 80% of the total content of water in the order of (F), (A), (B), (D), and (E), finally adding water to the predetermined volume, and stirring at room temperature for 20 minutes. The solution was heated to the predetermined temperature, and pH was adjusted. The surface treated metal plate was rinsed with water, and then with deionized water, and without drying, the metal plate was subjected to the electrodeposition by using the procedure and conditions as described above to thereby form the coating.

[0175]Chemical Conversion Solution 2

[0176](A): tin fluoride, 1 mmol / L

[0177](B): fluorotitanic acid, 5 mmol / L

[0178](C): nitrate radical from (D) and (E), 40 mmol / L

[0179](D): aluminum nitrate, 10...

example 3

[0184]Chemical conversion solution 3 having the following composition was prepared, and surface treatment of the three types of the metal plate and the box was conducted by the surface treating method (2). The chemical conversion solution was prepared by adding the following components (A) to (F) to 80% of the total content of water in the order of (F), (A), (B), (D), and (E), finally adding water to the predetermined volume, and stirring at room temperature for 20 minutes. The solution was heated to the predetermined temperature, and pH was adjusted. The surface treated metal plate was rinsed with water, and then with deionized water, and without drying, the metal plate was subjected to the electrodeposition by using the procedure and conditions as described above to thereby form the coating.

[0185]Chemical Conversion Solution 3

[0186](A): germanium fluoride, 0.5 mmol / L

[0187](B): fluorotitanic acid, 0.1 mmol / L; fluorozirconic acid, 0.5 mmol / L

[0188](C): nitrate radical from (D) and (E...

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Abstract

The present invention provides a chemical conversion solution and the surface treating method for realizing high corrosion resistance and high coating adhesion of the metal surface, as well as high throwing power during electrodeposition, and generating no sludge.A chemical conversion solution comprising (A) at least one compound selected from water-soluble germanium compound, water-soluble tin compound, and water-soluble copper compound, (B) at least one compound selected from water-soluble titanium compound and water-soluble zirconium compound, (C) at least one water-soluble nitrate compound, (D) at least one compound selected from water-soluble aluminum compound and water-soluble magnesium compound, (E) at least one water-soluble zinc compound, and (F) at least one fluorine compound, and, the coating process for the metal structure.

Description

CROSS-REFERENCE TO RELATED CASES[0001]This application is a continuation under 35 U.S.C. Sections 365(c) and 120 of International Application No. PCT / JP2009 / 061859, filed Jun. 29, 2009 and published on Jan. 7, 2010 as WO 10 / 001,861, which claims priority from Japanese Patent Application Serial No. 2008-172616 filed Jul. 1, 2008, which are incorporated herein by reference in their entirety.BACKGROUND OF THE INVENTION[0002]This invention relates to a novel chemical conversion solution for a metal surface, and in particular, for a surface of a metal structure which provides excellent corrosion resistance and improved coating adhesion to the metal surface. This invention also relates to a novel surface treating method for a metal structure.[0003]Chemical conversion for the purpose of improving the corrosion resistance and coating adhesion of a metal has been known in the art for a long time. The most popular chemical conversion is phosphate treatment using an acidic aqueous solution of ...

Claims

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Application Information

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IPC IPC(8): C23C22/48
CPCC09D5/08C09D5/4473C25D13/20C23C22/34C25D5/34C09D5/448
Inventor YOSHIDA, MASAYUKINAGASHIMA, YASUHIKOKAWAGOSHI, RYOSUKE
Owner HENKEL KGAA
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