JP2002047579A - Surface-treated metallic material excellent in black appearance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-treated metallic material excellent in black appearance and also good in weldablity, flawing resistance and the adhesive strength of coating film after working. SOLUTION: The surface of a metallic base material in which Zn is present on the surface is substitutionally deposited with one or more kinds of metals selected from the groups consisting of Ni, Co and Fe by 30 to 200 mg/m2 to form an oxide layer of those elements. It is recommended that a black film and a clear film are further applied on the surface for improving its blackening degree, weldability, flawing resistance and the adhesive strength of coating film after working.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated metal material having an excellent black appearance, and more particularly to the use of a color tone of a metal substrate subjected to a chemical undercoating. The present invention relates to a surface-treated metal material that can exhibit good weldability and the like even when a metal thin film is coated with a black thin film and has both high blackness and weldability.

[0002]

2. Description of the Related Art In the fields of home electric appliances and automobiles, there is a growing need for black metal materials having excellent black appearance and imparting properties such as weldability. In order to meet such needs, conventionally, a method of applying a black resin film containing a black inorganic pigment such as carbon black or a black dye on the surface of a metal base material has been adopted.

However, in the above-mentioned method, the thickness of the film must be increased in order to obtain a desired degree of blackness, which causes a problem that other characteristics are deteriorated. For example, when carbon black, which is generally used as a black pigment, is used for the pigment, the pigment itself has a small hiding effect, so that the coating thickness must be increased to 10 μm or more in order to obtain a desired black color tone. In addition, it may cause other properties to be impaired, such as exceeding a weldable thin film thickness (generally, 5 μm or less).

As a method for solving such a problem, Japanese Patent Application Laid-Open No. 63-59377 and Japanese Patent Application Laid-Open No. 2-78540 disclose a Zn-based electroplated steel sheet (mainly electric Zn-N
i-alloy-plated steel sheet) by subjecting it to an electrolytic treatment such as anodizing treatment in an acid plating bath or anodic or cathodic electrolytic deposition in an alkaline solution to form a black inorganic film on the base steel sheet first. Furthermore, the thickness of the black film to be coated is reduced. However, since such an electrolytic treatment method has complicated facilities and the like, it is desired to perform a base treatment of the metal base material by a simpler method.

[0005] As a base treatment other than the above-mentioned electrolytic treatment,
Japanese Patent Application Laid-Open No. 63-59377 discloses an immersion method for immersing a metal base material in a copper sulfate solution / nitric acid solution to obtain a black film. However, in order to obtain a black inorganic film by the above method, it is necessary to use an expensive Zn-Ni alloy-plated steel sheet as a substrate, and it is desired to establish a method using a less expensive metal substrate not containing Ni. .

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a surface-treated metal material which can be obtained by using a metal substrate having an excellent black appearance, and which is excellent in weldability, film adhesion after processing, and scratch resistance.

The present invention does not positively exclude the use of a Zn-Ni alloy-plated steel sheet as described above as a metal substrate, but uses the Zn-Ni alloy-plated steel sheet as a metal substrate. Even in this case, a surface-treated metal material having an excellent black appearance can be obtained.

[0008]

The surface-treated metal material of the present invention which can solve the above-mentioned problems is selected from the group consisting of Ni, Co, and Fe on a metal substrate having Zn on the surface. The gist of the invention is that one or more kinds of metals to be formed are substituted with 30 to 200 mg / m ² to form oxide layers of these metals, and the metal base material is a Zn-based plated steel sheet. Is a preferred form.

[0009] Furthermore, 0.5 g /
It is preferable that m ² or more black coating is formed,
More preferably, it is 0.5 to 4 g / m ² .

Preferably, a clear film is formed on the black film in an amount of 0.2 g / m ² or more. In this case, the total amount of the black film and the clear film is 4 g / m ^2.
g / m ² or less.

The production method of the present invention is a method useful for producing a surface-treated metal material having an excellent black appearance as described above. C
at least one metal selected from the group consisting of
0 to 200 mg / m ^{2, and} an oxide layer of these metals is formed, and a black film is formed thereon. In this case, Zn is used as the metal substrate. A system-plated steel sheet is preferably used.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Under the above-mentioned circumstances, the present inventors have studied with the aim of realizing a surface-treated metallic material having an excellent black appearance and imparted weldability, scratch resistance and the like. did. As a result, a conventional black metal material does not particularly specify a metal substrate to be used, and generally uses an electrogalvanized steel sheet (E
G), various galvanized steel sheets such as hot-dip galvanized steel sheet (GI) and galvannealed steel sheet (GA) are used at random, but if a metal substrate having Zn on the surface is used, It has been found that a dark metal oxide layer can be easily formed using Zn, and the thickness of a black film formed thereon can be considerably reduced. After further study, they found that it is effective to use Ni, Co, and Fe as a metal for forming an oxide layer by substitution precipitation with Zn on the surface of the metal substrate, and reached the present invention. did.

In other words, according to the present invention, even when a metal base material free of Ni, which is an expensive element, is used, a base treatment plate having a blackness sufficient to obtain a black metal material can be obtained. The amount of black film to be formed can be considerably reduced,
As a result, it is possible to eliminate the obstacle caused by forming the thick black film as described above.

Hereinafter, in addition to the oxide layer, which is a point of the surface-treated metal material of the present invention, a black film and a clear film formed on the oxide layer, and a usable metal substrate will be described in detail.

(1) Oxide layer As described above, the present inventors have studied the Z
By substituting and precipitating n with Ni, Co, and Fe to form a brown oxide layer, the color tone of the surface of the metal substrate can be made darker, and the metal base on which the oxide layer is not formed can be obtained. Compared with the material, the amount of the black film to be coated could be considerably reduced.

The oxide layer is affected by the amount of substitutional precipitation of Ni, Co, and Fe. If the amount is insufficient, the color tone change of the metal substrate is so small that sufficient blackness cannot be obtained. Therefore, the substitution precipitation amount of the above element is 30 mg / m ² or more, preferably 40 m / m ² or more.
g / m ² or more, more preferably 50 mg / m ² or more. However, when the substitution precipitation amount of these metals is too large, the corrosion resistance, weldability and adhesion to the black coating film are liable to be reduced, and therefore 200 mg / m ² or less, preferably 150 mg / m ² or less, more preferably. Is 130m
g / m ² or less.

Incidentally, among Ni, Co and Fe, when Ni is used, an oxide layer having a higher degree of blackness can be obtained. Therefore, it is preferable to use Ni as the substitution precipitation metal.

An example of the above-mentioned substitution precipitation method is an immersion treatment method. The reason why the immersion treatment method is more effective than the electrolytic treatment method is that the immersion treatment method is simpler in terms of equipment, and the electrolytic treatment method also precipitates a white metal in addition to the black metal oxide. Since a large amount of precipitation is required to obtain a high blackness, the immersion treatment precipitates only the black metal oxide. Therefore, a sufficiently dark deposited layer can be formed even with a thin wall.

When an oxide layer is formed on a metal substrate by the immersion treatment method, Ni, Co or Fe
A sulfuric acid compound, a nitric acid compound or a hydrochloric acid compound, Zn
A sulfuric acid compound, a nitric acid compound or a hydrochloric acid compound, sulfuric acid,
It is recommended to use inorganic acids such as nitric acid, hydrochloric acid and hydrofluoric acid, and those containing hydroxycarboxylic acids such as tartaric acid and citric acid used as chelating agents.

The amounts of substitutional precipitation of Ni, Co, and Fe can be adjusted by changing the concentration, pH, or treatment time of each compound in the treatment solution. It is effective to use a reducing agent such as an antimony compound.

In the above description, Zn on the surface of the metal substrate is changed to N
As a method of forming an oxide layer by substituting and depositing i, Co, and Fe, a method of immersing a substrate in a treatment liquid as described above has been exemplified. To form an oxide layer.

(2) Black film When using as a black metal material, it is recommended to form a black film of 0.8 g / m ² or more on the oxide layer in order to secure more stable blackness. The black film is more preferably formed at 1.0 g / m ² or more. However, even if the amount of the black film is too large, the effect of improving the degree of blackness is saturated, which is not only wasteful, but also causes deterioration of the film adhesion after processing.
m ² or less, more preferably 6 g
/ M ² or less. To give particularly good weldability,
The amount of the black film is preferably 4 g / m ² or less, more preferably 3 g / m ² or less.

Conventionally, as a pigment used for forming a black film, a black pigment such as carbon black or the like (eg, TiO ₂ , CaCO ₃ , BaS
O _4, etc.) have been used after adding. However,
In the present invention, since the color tone of the surface of the metal substrate subjected to the undercoat treatment is actively used, the black film forming agent does not include the pigment for the purpose of hiding, and substantially only carbon black. Is preferred.

However, in the present invention, the addition of other pigments is not excluded.
It is also possible to add it within a range that does not impair the action of the present invention.

When carbon black is used as a coloring pigment, the amount of the carbon black added is a solid content (hereinafter the same),
The content is preferably set to 3 to 20% by mass. If the amount is less than 3% by mass, it is difficult to obtain a desired degree of blackness, while if it exceeds 20% by mass, the stability of the liquid and the paintability are likely to be adversely affected. More preferably, it is 6% by mass or more and 18% by mass or less.

The resin used for forming the black film is not particularly limited, but may be an acrylic resin, a urethane resin, a polyolefin resin, a polyester resin, a fluorine resin, a silicon resin, or a mixture or a mixture thereof. A modified resin or the like can be used as appropriate. It is also effective to adjust the film hardness by using an appropriate amount of a crosslinking agent together with these resins. Examples of the crosslinking agent include melamine compounds and isocyanate compounds,
One or more of these can be added in the range of 0.5 to 20% by mass.

(3) Clear Coating In the present invention, it is effective to coat the above black coating with a clear coating in order to enhance the scratch resistance, and the preferable coating amount of the clear coating is 0.3 g / m ² or more. More preferably, it is 0.4 g / m ² or more. However, if the amount of the clear film is too large, the film adhesion after processing deteriorates.
It is preferably suppressed to 0 g / m ² or less, more preferably 8 g / m ² or less.

When the clear film is coated on the black film as described above, if the total amount of both films increases, the weldability and the adhesion of the film after processing are liable to deteriorate. Is preferably 4 g / m ² or less, and more preferably 3 g / m ² or less.

The resin constituting the clear film is not particularly limited. Resins such as acrylic resin, urethane resin, polyolefin resin, polyester resin, fluorine resin, silicon resin and the like, Or a modified resin or the like can be used. Further, a crosslinking agent, a wax, a matting agent, a pigment and the like can be added as long as the action of the present invention is not impaired.

<Metal Substrate> The present invention relates to a method for producing a metal substrate having a Z
n is replaced by Ni, Co, and Fe, and Ni, C
Since an oxide layer of o and Fe is formed, any metal material containing Zn in the surface layer may be used. If the amount of Zn on the metal substrate is too small, the amount of oxides generated is insufficient and it is difficult to obtain an excellent black appearance, so that Zn of 5 g / m ² or more exists on the surface of the metal substrate. Is preferably used as the metal substrate.

As the metal substrate, a metal plate or a wire can be used. As the metal plate, a steel plate, an Al plate,
It is possible to use a plate based on a Cu plate, a SUS plate, a Ti plate, or the like and plated with Zn by electroplating or hot-dip plating. For example, when a steel sheet is used as a base material, an electrogalvanized steel sheet, a 5% Al-Zn hot-dip galvanized steel sheet, a 55% Al-Zn hot-dip galvanized steel sheet, or the like can be used. As the wire rod, mild steel wire, hard steel wire, Cu
A wire, a brass wire, or the like may be used as a base, and the surface of which is plated with Zn by the above-described method may be used.

[0032]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and the present invention is not limited thereto. Modifications can be made and implemented, all of which are included in the technical scope of the present invention.

That is, in the following embodiments, a Zn-based plated steel sheet is used as the metal substrate, but the use of various metal substrates as described above as the metal substrate is also included in the scope of the present invention.

First, immersion treatment was performed using the various types of plated steel sheets shown in Table 1 under the following conditions, to prepare base treated sheets having an oxide layer formed on the steel sheets. Next, on the base treatment plate,
A test sample was obtained by applying a black paint and a clear paint having the following compositions with a bar coat.

[0035]

[Table 1]

<Immersion treatment> Liquid composition: Ni sulfate, Co sulfate, Fe sulfate: 5 to 20 g / l in total Chelating agent (citric acid): 1 to 10 g / l Zn sulfate: 80 to 100 g / l Hydrogen fluoride: 1 to 10 g / l Aluminum sulfate: 1 to 10 g / l Immersion time: 3 to 20 seconds Treatment temperature: 50 to 70 ° C <Black paint and clear paint> For clear paint, xylene of polyester resin (molecular weight 20000 to 25000) is used. And a resin solution in which a melamine resin agent was added as a crosslinking agent to a mixed solution of cyclohexanone. In addition, the ratio of polyester and melamine was polyester: melamine = 9: 1 in terms of solid content mass ratio.

As the black paint, one obtained by adding carbon black to the clear paint was used. The ratio of the polyester, melamine and carbon black was polyester: melamine: carbon black = 9: 1: 1.5 in terms of the solid content mass ratio.

With respect to the sample thus obtained,
The characteristics were examined as follows.

(1) Black Appearance Using a color difference meter (SZ-S # 90) manufactured by Nippon Denshoku Co., Ltd., the L value of each sample was measured based on the method specified in JIS Z 8729, and based on the following criteria. The blackness was evaluated. ◎: L ≦ 30 ○: 30 <L ≦ 35 △: 35 <L ≦ 40 ×: L> 40

(2) Adhesion of the film after processing According to JIS K 5400, the film was bent 180 ° using a mandrel having a diameter of 3 mm, and then tightly bent by a hydraulic press. Next, after taping the tightly bent portion with Nichiban cellophane tape, the cellophane tape was peeled off and the degree of film peeling was evaluated according to the following criteria.

The "film peeling" in the following criteria is
It refers to the case where only the black film is peeled off, and the case where the oxide layer and the black film are peeled off together at the oxide layer portion. ◎: No abnormality ○: Slight peeling △: Film peeling ×: Large film peeling

(3) Scratch resistance After forming a cylinder with an 80 t crank press, the appearance of the side surface was visually evaluated. The test conditions and evaluation criteria are as follows. In addition, "film peeling" in the following evaluation criteria
As in the case of the film adhesion test after the above-mentioned processing, the term refers to the case where only the black film is peeled off, and the case where the oxide layer and the oxide layer are peeled off together at the oxide layer portion. Evaluation criteria ◎: No abnormality ○: Slight film flaw and appearance change △: Film peeling ×: Large film peeling

(4) Weldability Spot welding was performed under the following conditions, and the number of continuous spots was measured. Electrode: Cr-Cu, D-type Electrode diameter: 6 mmφ Welding current: Apply a current value that ensures a nugget diameter of 5 以上 t (t is the thickness of the steel plate) or more. Energizing pressure: 200 kg Energizing time: 12 cycles / 60 Hz The following criteria were evaluated according to the obtained number of continuous hit points. ◎: 300 dots or more ○: 100 dots or more and less than 300 dots ×: less than 100 dots

Example 1 In this example, the effect of the underlayer treatment conditions for forming an oxide layer and the amount of a black film on the black appearance and the film adhesion after processing when a clear film was not applied was investigated. The results are as shown in Table 2 below.

[0045]

[Table 2]

No. Nos. 1 to 19 satisfy the conditions preferred in the present invention, and excellent results are obtained in black appearance and film adhesion after processing.
On the other hand, No. No. 20 was not subjected to a base treatment for forming an oxide layer, and No. 21 is insufficient in the amount of substitution precipitation, and Sample No. 23 was inferior in black appearance due to insufficient black coating amount. No. In No. 22, the adhesion after processing was inferior because the substitution precipitation amount was too large.

Embodiment 2 In this embodiment, the base treatment conditions for forming an oxide layer
The effects of the amount of the black film and the amount of the clear film on the black appearance, film adhesion after processing, and scratch resistance were examined. The results are shown in Table 3 below.

[0048]

[Table 3]

No. 25 to 30 and No. In Nos. 32 to 36, almost satisfactory results were obtained in all of the black appearance, the film adhesion after processing, and the scratch resistance. On the other hand, no. 24 and No. Sample No. 31 was slightly inferior in scratch resistance because no clear film was applied.

Example 3 In this example, the amount of the black film when only the black film was provided on the oxide layer, or the total amount of both the black film and the clear film when the black film and the clear film were coated, was changed to the black appearance. And the effects on the film adhesion, flaw resistance and weldability after processing, and the results are as shown in Table 4 below.

[0051]

[Table 4]

No. 40, 41, 44, 45, 47 and 48 are those in which the amount of the black film, or the total amount of the black film and the clear film satisfies the conditions specified in the present invention and the preferable conditions, the black appearance, Almost satisfactory results were obtained for all of the adhesiveness, scratch resistance and weldability. No. 37, 38, and 39 satisfy the conditions specified in the present invention and can obtain excellent weldability. However, in order to further impart film adhesion and flaw resistance after processing, an appropriate amount is used. Is preferably applied.

No. In Nos. 42 and 43, the black film amount exceeded the preferable range. 46 and 49
Since the total amount of the black film and the clear film exceeded the preferred range, the results were both inferior in weldability.

[0054]

The present invention is configured as described above, and is selected from the group consisting of Ni, Co, and Fe on a metal substrate having Zn on the surface in the production of a black metal material. By substituting and depositing one or more metals at 30 to 200 mg / m ² to form an oxide layer of these metals, the black appearance is excellent and the weldability, scratch resistance, and film adhesion after processing are also improved. A good surface-treated steel sheet could be obtained. The realization of such a surface-treated steel sheet having an excellent black appearance has made it possible to provide inexpensive and easy-to-handle black metal materials to the fields of home electric appliances and automobiles.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B32B 15/08 B32B 15/08 G C23C 18/32 C23C 18/32 28/00 28/00 C (72) Inventor Tadashige Nakamoto 1 Kanazawa-cho, Kakogawa-shi, Hyogo Prefecture Kobe Steel Works Kakogawa Works F-term (reference) BA03 BA04 BA07 BA10A BA10C BA10D CA02 CA13 CC00C CC00D EH112 EH46 EH71A EJ01 EJ64 GB33 GB48 HB00 JK06 JL10 JL10C YY00B YY00C YY00D 4K022 AA02 AA32. CA38 DA16 EB08 4K044 AA02 AB02 BA10 BA12 BA21 BB03 BB04 BB05 BC06 BC08 BC09 CA11 CA15 CA16 CA18 CA53

Claims (8)

[Claims] At least one metal selected from the group consisting of Ni, Co, and Fe is substituted on a metal substrate having Zn present on its surface by 30 to 200 mg / m ² and these metals are deposited. A surface-treated metal material having an excellent black appearance, characterized by forming an oxide layer of 2. The surface-treated metal material according to claim 1, wherein the metal substrate is a Zn-based plated steel sheet. 3. The surface-treated metal material according to claim 1, wherein a black film is further formed on the oxide layer in an amount of 0.5 g / m ² or more. 4. The surface-treated metal material according to claim 3, wherein the amount of the black film is 0.5 to 4 g / m ² . 5. A clear film is further formed on said black film in an amount of 0.2 g / m ² or more.
2. The surface-treated metal material according to item 1. 6. The surface-treated metal material according to claim 5, wherein the black film and the clear film are formed in a total of 4 g / m ² or less. 7. At least one metal selected from the group consisting of Ni, Co, and Fe is substituted for 30 to 200 mg / m ² on a metal substrate having Zn on its surface, and these metals are deposited. A method for producing a surface-treated metal material, comprising: forming an oxide layer of (1), and further forming a black film thereon. 8. The method for producing a surface-treated metal material according to claim 7, wherein the metal substrate is a Zn-based plated steel sheet.