JPS6039198A - Pigmenting method of magnesium or its alloy - Google Patents

Abstract

PURPOSE:To provide the ornamental pigmentation with corrosion resistance by forming an Al2O3-contg. coating on the surface of Mg or the alloy thereof, and pigmenting the coating with a dye for pigmenting alumite. CONSTITUTION:A spinel coating is formed on the surface of Mg or the alloy thereof by anodic oxidation. The anodic oxidation treating liquid is obtained by dissolving in 1l aq. treating liquid one or >=2 kinds selected from 20-300g aluminate, 0.5-20mol alkali hydroxide per 1mol said aluminate, 20-200g boron compd., 2-80g carboxylate, 2-50ml phenols, 2-50g sulfate, and 5-70g iodine compd. The coating is formed at about 5-70 deg.C, 10-15V, and 0.8-10A/dm<2>. The coating is pigmented in optional hues at about 55-65 deg.C with a dye for pigmenting alumite which is regulated to about 1-10g/l concn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coloring magnesium or its alloy.

Although magnesium and its alloys have excellent mechanical properties, they also have the drawbacks of being chemically active and susceptible to corrosion.

Therefore, when magnesium and its alloys are put to practical use, it is necessary to perform some kind of surface treatment to compensate for these two drawbacks, and various surface treatment methods have been proposed and implemented in the past.

Surface treatment methods for magnesium and its alloys can be roughly divided into chemical conversion treatment methods and anodic oxidation treatment methods. As a typical chemical conversion treatment method, for example, JIS-H-8651
(1978), 1 to 4, and 7. Further, as a typical anodizing treatment method, for example, the method described in Types 5 and 6 of J I 5-H-8651 (1978) (5 types of treatment liquid components: ammonium nitrate, sodium dichromate, and ammonia water, 6
Seed treatment liquid components: sodium hydroxide, ethylene glycol, sodium oxalate, sodium dichromate and acidic sodium fluoride), MIL standard (MI L-M-
45202B) (treatment liquid components:
Potassium hydroxide, potassium fluoride, sodium phosphate,
aluminum hydroxide and potassium permanganate), D
ow-17 method (processing liquid component ammonium dihydrogen difluoride,
sodium dichromate and phosphoric acid).

However, all of these conventional methods have problems. For example, the chemical conversion treatment method has a simple treatment process, but
Since this treatment method is generally used for temporary corrosion protection, there is a major drawback in that the surface of treated magnesium and its alloys has poor corrosion resistance.

On the other hand, the anodizing method is generally used for long-term corrosion protection, and some of these methods, such as the HAE method and the Dow-17 method, provide considerably superior corrosion resistance. Regarding gender, there is room for further improvement. That is, there is a problem in that the surfaces of magnesium and its alloys treated by these known methods tend to take on a dark brown or dark green color.

Magnesium and its alloys, whose surfaces have become dark-colored due to anti-corrosion treatment, have disadvantages when used as component lumber for general products, even if there is no real problem in terms of their performance. There are many. That is, when magnesium and its alloys are used as constituent materials for general products, the surface of the magnesium is often colored in a manner appropriate for the product in order to enhance the decorativeness of the product. However, if you try to color or decorate a surface that has been given a dark color using chemical methods, electrochemical methods, painting, etc., it will be difficult to color it in the desired color or obtain the desired hue. There is a drawback.

Regarding the anodizing treatment of the surface of magnesium and its alloys and the improvement of decorativeness after the treatment, Japanese Patent Application Laid-Open No. 55-760
94, after electrolytically treating (anodizing) magnesium or its alloy in an alkaline electrolytic bath consisting of trisodium phosphate and an organic acid (or an inorganic acid or a salt thereof), a dye for dyeing aluminum (for coloring alumite) is used. There is a description of a method of using dyes to color the treated surface after anodizing treatment, but in this case, a treatment to prevent decolorization of the dye is required, and the treatment process is complicated.

In view of these circumstances, the present inventor conducted extensive research with the aim of finding a method for coloring magnesium or its alloy that has excellent corrosion resistance and decorative properties.

As a result, when a film containing aluminum oxide is formed on the surface of magnesium or its alloy, the film has excellent corrosion resistance and can be easily colored with an alumite coloring dye. It has been discovered that the image is very clear and robust, and the present invention has been achieved.

That is, the present invention provides a method for coloring magnesium or its alloy, which comprises forming an aluminum oxide-containing film on the surface of magnesium or its alloy, and then coloring the film with an alumite coloring dye.

In the present invention, the aluminum oxide-containing film formed on the surface of magnesium or its alloy is spinel (MgO
- Sentence A 203) is desirable. Such a spinel film can be formed, for example, on the surface of magnesium or its alloy by anodizing the surface using an anodizing solution containing an aluminum compound.

As an example of the anodic acidification treatment liquid that is advantageously used in the coloring method of the present invention, 20 to 3
00g of aluminate, the alumin% fp 0 per mole
．． 5 to 20 moles of alkali hydroxide, and one or more selected from 20 to 200 g of boron compounds, 2 to 80 g of carboxylates, 2 to 50 g of phenols, 2 to 50 g of sulfur, 2 to 50 g of salts, and 5 to 70 g of iodine compounds. An anodizing solution formed by dissolving two or more types can be mentioned.

By anodizing magnesium or its alloy using the anodizing solution described in 1-, the spinel film formed on the surface becomes white, and the surface is coated with aluminum dye (alumite coloring dye). ) It has the advantage that it can be easily colored to any hue by immersing it in a dyeing bath containing .

The main components of the above anodizing solution are aluminate,
Since it is an alkali hydroxide and does not contain heavy metals such as chromium and manganese, and fluorine components as essential components unlike conventionally known anodizing solutions, it has the advantage of being easy to treat the waste fluid. However, even in this anodizing solution, if it is desired to impart particularly high corrosion resistance to the surface of the resulting magnesium and its alloy, it is advantageous to use a treatment solution containing dichromic acid. In this case, chromium treatment is required.

The white anodic oxide film (spinel [MgO・A n 203] film formed on the surface of magnesium or its alloy) obtained using the above-mentioned anodizing solution contains aluminum oxide, so it cannot be used in conventionally known methods. It can be easily colored in various hues by a method similar to the alumite coloring method.

The compound of the film formed on the surface of magnesium and its alloy by a known anodic oxidation method (JIS type 6, fluoride method, etc.) is magnesium hydroxide [Mg
(O)()2], magnesium fluoride [MgF2]
or magnesium oxide [MgO], and if the treated surface is white, it is possible to color the surface using an alumite coloring dye in a method similar to the alumite coloring method. However, in these cases, since the film does not contain an aluminum oxide component, the dye adsorption property is poor, and decolorization easily occurs when the colored surface is rubbed with white paper, so it is not preferred in practice.

Spinel (MgO-A
Sentence 203) It is assumed that the aluminum oxide component of the film chemically reacts with the dye and adsorbs the dye, and therefore no decolorization is observed even when rubbing with white paper, etc., and the coloring state is clearly good. shows.

Magnesium and alloys thereof that can be subjected to the coloring treatment of the present invention are not particularly limited, but include magnesium, which is generally used as an industrial material, in an amount of about 70% by weight or more, and other materials such as aluminum, zinc, Magnesium alloys containing manganese, zirconium, silicon, rare earth elements, etc. can be particularly advantageously applied.

Next, an anodizing solution that can be advantageously used for the purpose of forming an aluminum oxide-containing film in the method for coloring magnesium or its alloy according to the present invention will be described.

This anodizing solution dissolves an aluminate, an alkali hydroxide, and one or more selected from the group consisting of boron compounds, carboxylates, phenols, sulfates, and 7-iodinated compounds. This is an aqueous anodizing solution.

The aluminate to be included in the above anodizing solution is preferably one that is soluble in water, typical examples of which include alkali metal salts of aluminate such as sodium aluminate and potassium aluminate. I can do it. The content of these aluminates needs to be in the range of 20 to 300 g, particularly preferably in the range of 30 to 250 g, based on the aqueous treatment liquid 11. If the amount of aluminate used is too small, it will not be possible to form a spinel film on the surface of magnesium or its alloy, and if it is too large, the aluminate ions will be hydrolyzed and aluminum hydroxide will precipitate in the treatment solution. This is not preferable because it tends to generate.

The alkali hydroxide contained in the anodizing solution is effective in preventing the aluminate ions in the solution containing aluminate from being hydrolyzed, and the amount used is determined by the amount of aluminate in the solution. Although it is closely related to the amount of aluminate ion, generally 0.5 to 20
It is necessary that the amount is within a molar range, and particularly preferably 1 to 10 moles. If the number of alkali hydroxide stars is too small, aluminum hydroxide precipitates are likely to form, and if the number is too large, it will adversely affect the corrosion resistance of the magnesium or its alloy obtained by the treatment, which is not preferable. Representative examples of the alkali hydroxide to be included in the above anodizing solution include sodium hydroxide and potassium hydroxide.

The above anodizing solution consists of water with a specified star aluminate,
Alkali hydroxide and one or more compounds selected from the group consisting of boron compounds, carbone sth, phenols, sulfates and iodine compounds as additives within the range specified for each compound. It can be prepared by dissolving it. However, aluminate can also be obtained by dissolving aluminum or other aluminum compounds such as aluminum hydroxide in an aqueous solution of an alkali hydroxide such as thorium hydroxide or potassium hydroxide, so the anode When preparing the oxidation treatment liquid, aluminum hydroxide or aluminum may be used instead of the aluminate to prepare the treatment liquid.

In preparing the above anodizing solution, there is no particular restriction on the order of addition when dissolving aluminate and alkali hydroxide in water, but aluminum or aluminum hydroxide may be used instead of aluminate. In some cases, it is appropriate to dissolve aluminum or aluminum hydroxide in an aqueous solution of alkali hydroxide and then add various additives. Furthermore, it is appropriate that the water used be one that does not contain chlorine ions.

The anodizing solution preferably used in the present invention is
As mentioned above, one or more additives selected from the group consisting of boron compounds, carboxylates, phenols, sulfates, and iodine compounds that are soluble in the processing solution are dissolved. When the surface of magnesium and its alloys is anodized using such an anodizing solution, remarkable improvements are observed in the corrosion resistance and abrasion resistance of the surface and the uniformity of the treated surface.

The boron compound used as an additive is one that is soluble in water, and the addition of this boron compound significantly improves corrosion resistance. Furthermore, the amount added in this case is preferably such that no undissolved residue remains or precipitates are formed, and the amount of boron compound added is generally 20 to 200 g.
/l (per liter of prepared anodizing solution, the same applies hereinafter)
It is necessary to be within the range of . Examples of such boron compounds include potassium metaborate, sodium metaborate, ammonium metaborate, metaboric acid, sodium tetraborate, and the like.

The carboxylic acid salt used is one that is soluble in the processing solution and does not react with other components in the processing solution to form a precipitate. Typical examples thereof include formic acid, acetic acid, propionic acid, Monocarboxylic acids such as butyric acid, oxalic acid, malonic acid,
Mention may be made of dicarboxylic acids such as succinic acid and adipic acid, oxycarboxylic acids such as lactic acid, tartaric acid, and citric acid, and alkali metal salts (eg, sodium salts, potassium salts, etc.) and ammonium salts of various carboxylic acids. The amount of these carboxylates added is 2 to 80 g.
/n, especially 5 to 60
It is preferable to use it so that it becomes g/l. If the amount of carboxylate added is small, carboxylic acid j! No effect was observed due to the addition of ', and if the amount is too large, too much current will flow during the anodizing process, making it impossible to obtain a good anodic oxide film.

Phenols used are those that are soluble in the processing solution and do not react with other components in the processing solution to form a precipitate. Typical examples include phenol, sodium phenol, and phenol. -2,4-disulfonebutyric, 0
-phenolsulfonic acid, p-phenolsulfonic acid, and the like. The amount of these phenols added must be in the range of 2 to 50 ml/l, and particularly preferably 2 to 25 ml/l. If the amount of phenol added is too small, the effects of phenol addition will not be observed, and if it is too large, the current will concentrate in one place and flow too much during the anodic oxidation process, resulting in poor anodic oxidation. is not obtained.

The sulfate is preferably one that is soluble in the processing solution and does not react with other components in the processing solution to form a precipitate. Examples of such sulfates include sodium sulfate, potassium sulfate, ammonium sulfate, and the like. The amount of sulfate added is 2 to 50 g/l
It is necessary to be in the range of 2 to 25 g/
Preferably, it is used with l. In other words, if the sulfate content is too low, no improvement in corrosion resistance is observed due to the use of sulfuric acid (JH), and if it is too high, current will flow excessively during the anodizing process, resulting in poor anodic oxidation. I can't do it.

As the iodine compound, it is necessary to select one that is soluble in the processing solution and does not react with other components in the processing solution to form precipitates. Examples of such iodine compounds include:
Alkali metal salts of iodine (e.g. sodium fi,
potassium salts, etc.) and ammonium salts. The amount of these iodine compounds added is 5 to 70 g/l
It is necessary to be in the range of 5 to 50 g/
f) is preferably used. That is, if the amount of the iodine compound added is too small, no effect will be observed due to the use of the iodine compound, and if it is too large, too much current will flow during the anodizing treatment, making it impossible to obtain a good anodic oxide film.

In the preparation of the anodizing solution described in 1-, the above-mentioned additives used can be used either singly or in combination of two or more as described above, but particularly preferred embodiments are: This is an embodiment in which a boron compound and an iodine compound are used together.

The above-mentioned anodizing solution can also contain chromate in addition to the above-mentioned additives, and the addition of chromate improves the corrosion resistance of the anodized magnesium and its alloy surfaces. Further improvement. Therefore, it is necessary to select a romate salt that is soluble in the processing solution and does not react with other components in the processing solution to form a precipitate. Examples of such romate salts include potassium dichromate, sodium dichromate, ammonium dichromate, and the like. It is necessary that the amount of these chromium M salts added is in the range of 2 to 100 g / sentence,
In particular, it is preferable to use 5 to 50 g/u. If the amount of chromate added is too small, the effects of using chromate will not be observed, and if it is too large, the surface condition of the resulting anodic oxide film will be unfavorable.

When anodizing magnesium or its alloy using the anodic oxidation solution described in 2 above, it is appropriate that the temperature of the treatment solution be in the range of 5 to 70°C. If the temperature of the processing liquid is too low, the cooling device for the processing liquid will need to be enlarged, making it less economical.If the temperature becomes too high, the evaporation of the processing liquid will be significant, making it difficult to maintain a constant composition of the processing liquid. become. Therefore, it is appropriate that the temperature of the anodizing solution be within the above range. In addition, if the anodizing voltage is too low, a good spinel film will not be formed on the surface of magnesium or its alloy, and if it is too high, the anodizing reaction will proceed vigorously on a part of the surface, causing film discoloration. Therefore, a range of 10 to 150V is generally appropriate. In addition, the current density is 0.8 to 10 A/
It is appropriate to select from d m', and the treatment time is related to the film thickness, but it is appropriate to set it to 10 to 90 minutes.

- Magnesium or its alloy that has been anodized using an anodizing solution as described in 1. is washed with water and then dried; By doing so, a surface-treated product with excellent corrosion resistance and wear resistance can be obtained. The film formed on the surface of magnesium or its alloy by anodizing it using the above anodizing solution is
It has adhesion that is equal to or better than general anodic oxide film.

The white anodic oxide film formed on the surface of magnesium or its alloy by using the above-mentioned anodizing solution is the aluminum dye (alumite coloring dye) used when coloring the aluminum anodic oxide film with dye. ) can be easily colored in various hues.

In the present invention, the dye suitable for coloring the aluminum oxide-containing film formed on the surface of magnesium or its alloy is a dye for coloring alumite, and examples of the dye include known acid dyes, metal-containing complex salt dyes,
and acid mordant dyes.

When coloring with these dyes, the same controls as for coloring the aluminum surface may be carried out regarding the concentration of the dye, the pH of the coloring liquid, prevention of impurities from entering the coloring liquid, etc.

That is, a dye solution having a dye concentration of 1 to 10 g/ml is generally prepared, and if necessary, pH adjustment and additives such as surfactants are added to obtain a coloring dye solution. Regarding the conditions and aspects of the alumite coloring method, please refer to ``Metal Surface Technology Handbook j Edited by Metal Surface Technology Association (Nikkan Kogyo Shimbun Publishing Co., Ltd., 1976) and ``Aluminum Surface Technology Handbook j Aluminum Surface Technology Handbook Editorial Committee Wa (Keikinzoku Publishing) (published in 1980)
There is a detailed description.

However, regarding the temperature of the treatment solution (staining solution) in the alumite coloring method, in the case of aluminum surfaces, a temperature of about 55 to 65 degrees Celsius is generally well adopted. Since the anodic oxide film formed on the surface of Magnesium or its alloy does not undergo the phenomenon of sealing of the anodic oxide film due to boiling water, it is possible to carry out the coloring operation at even higher temperatures, even when using Ti staining solution. It is also possible to perform coloring treatment at a temperature of about 100"C. Therefore, since it is possible to use a high-temperature dyeing solution, the adsorption reaction of the dye is promoted, and coloring can be done in a short time. .

EXAMPLES Next, the present invention will be explained in detail with reference to Examples.

The anodizing solution used in each case is shown in Table 1, and the dye for coloring the alumite is shown in Table 2.

Table 1 Sodium aluminate 200g Sodium hydroxide 120g Potassium metaborate 100g Sodium iodide 30g Sodium aluminate 100g Sodium hydroxide 120g Phenol 10m Sodium aluminate 160g Sodium hydroxide 120g Sodium iodide 30g Potassium citrate 25g Sodium aluminate 40g Sodium hydroxide 140g Potassium metaborate 35g Potassium citrate 10g Sodium aluminate 50g Potassium hydroxide 120g Potassium fluoride 35g Potassium citrate 50g Sodium aluminate 50g Potassium hydroxide 140g Potassium fluoride 35g Potassium citrate 50g Potassium metaborate 35g Note) Each treatment solution was prepared by adding ion-exchanged water to each of the above components.
Used as an aqueous solution.

Table 2 M Dye base Type Notes I AluIIlinium Azo Red RLW non-metallic dye Manufactured by Sandoz Co., Ltd. 3 2 Aluminum Atraquinone Blue 2
LW non-metallic dye Sandoz 3 Aluminum
m Azo-based Violet CLW Metal complex dye Manufactured by Sandoz 4
Aluminum 7-type Yellow G3LW Metal complex dye Manufactured by Sandoz 5
, Aluminum Azo Green LW
N Metal complex dye Sandoz 6 Aluminum
Azo-based Gray NL Pa5te Metal complex dye Manufactured by Sandoz Co., Ltd. 7 ^1uma l light Azo-based Black
7? ? Metal complex dye Kaname Shokai 8 Ba5al
ox Azo-based Black SML Metal Complex Dye Manufactured by Kaname Shokai In addition, each piece is a test piece (length: 6 cm, width: 5 cm, thickness: 3 m) cut from a magnesium alloy plate (AZ31).
4) was polished with #400 sandpaper, subjected to alkali cleaning and acid cleaning, and immediately subjected to anodizing treatment using the above-mentioned anodizing solution. When using anodizing solutions (1) to (5), the treatment conditions are alternating current, current density 2
A / d m', treatment liquid temperature 25 ° C, treatment time 30 minutes, and when using anodizing treatment liquid (6), AC, current density 2 A / d + n', treatment liquid temperature 60 ° C 1 treatment time 30 minutes. And so.

The test pieces subjected to the above anodizing treatment were washed with water for 10 minutes and then subjected to subsequent coloring treatment.

[Example 1] Film thickness 257 obtained using anodizing solution (1)
A surface-treated product with a white spinel film of zm was treated with a dye (
Not) After being immersed in a 60° C. aqueous solution containing 2 g/l for 10 minutes for coloring treatment, it was washed with tap water for 10 minutes.

After drying, the treated surface exhibited a bright red color, and when this red surface was rubbed with white paper, the colored state was good.

[Example 2] Film thickness 257 obtained using anodizing solution (1)
A surface-treated product with a white spinel film of zm was treated with a dye (
No. 2) After being immersed in a 60° C. aqueous solution containing 3 g/u for 10 minutes for coloring treatment, it was washed with tap water for 10 minutes.

After drying, the treated surface exhibited a bright blue color. This blue surface was rubbed with white paper, but no change was observed in the colored state.

[Example 3] Film thickness 25 g obtained using anodizing solution (1)
A surface-treated product with a white spinel film of , m is treated with a dye (
No. 3) 1 in 60″C (7) aqueous solution containing 0.3 g/l
After being immersed for 0 minutes for coloring treatment, it was washed with tap water for 10 minutes. After drying, the treated surface exhibited a bright purple color. This purple surface was rubbed with white paper, but no change was observed in the colored state.

[Example 4] Film thickness 257 obtained using anodizing solution (1)
A surface treated product with a white spinel film of Lm was treated with a dye (
No.4) 1 in 60″C(r) aqueous solution containing 2.5g/n
After being immersed for 0 minutes for coloring treatment, it was washed with tap water for 10 minutes. After drying, the treated surface exhibited a bright yellow color. This yellow surface was rubbed with white paper, but no change was observed in the colored state.

[Example 5] Film thickness 25p obtained using anodic acidification treatment solution (1)
A surface treated product with a white spinel film of Lm was treated with a dye (
No. 5) Coloring treatment was performed by immersing in an aqueous solution containing 2.5 g/l at 60°C for 10 minutes, and then washing with tap water for 10 minutes. After drying, the treated surface showed a bright green color.

When this green surface was rubbed with white paper, no change was observed in the coloring state.

[Example 6] Film thickness 25p obtained using anodizing solution (1)
A surface-treated product with a white spinel film of
(No. 6) After being immersed in an aqueous solution containing 1 g/KL at 60'C for 10 minutes for coloring treatment, it was washed with tap water for 10 minutes. After drying, the treated surface exhibited a bright gray color. This gray surface was rubbed with white paper, but no change was observed in the colored state.

[Example 7] A coloring treatment was carried out in the same manner as in Example 6, except that the temperature of the aqueous solution containing the dye was 100'C, and the immersion time of the anodic diluted product was 5 minutes. After drying, the treated surface showed a black color. This black surface was rubbed with white paper, but no change was observed in the colored state.

[Example 8] Film thickness 25p obtained using anodizing solution (1)
A surface-treated product with a white spinel film of m
o7) After being immersed in a 60'C17) aqueous solution containing log/u for 10 minutes for coloring treatment, it was washed with tap water for 10 minutes. After drying, the treated surface showed a gray color. This gray surface was rubbed with white paper, but no change was observed in the colored state.

[Example 9] Film thickness 25 g obtained using anodic acidification treatment liquid (1)
A surface-treated 7 product having a white spinel film of 100 m was immersed in an aqueous solution at 60°C containing 10 g/l of dye (No. 8) for 10 minutes for coloring treatment, and then washed with tap water for 10 minutes. After drying, the treated surface showed a gray color. This gray surface was rubbed with white paper, but no change was observed in the colored state.

[Example 1O] Film thickness 6 gm obtained using anodizing solution (2)
A surface-treated product with a white spinel film is treated with a dye (Fi
l) Coloring treatment was carried out by immersing in a 95°C aqueous solution containing 2 g/kg for 10 minutes, and then washing with tap water for 10 minutes. After drying, the treated surface showed a bright red color. This red surface was rubbed with white paper, but no change was observed in the colored state.

[Example 11] Film thickness 14 g obtained using anodizing solution (3)
A surface-treated product with a white spinel film of m
o2) Coloring was performed by immersing in an aqueous solution containing Ig/u at 95°C for 10 minutes, and then washing with tap water for 108 minutes. After drying, the treated surface exhibited a bright blue color. This blue surface was rubbed with white paper, but no change was observed in the colored state.

[Example 12] Film thickness 47z obtained using anodizing solution (4)
A surface-treated product with a white spinel film of m
o3) Coloring was performed by immersing in an aqueous solution containing 0.5 g/l at 95°C for 10 minutes, and then washing with tap water for 10 minutes. After drying, the treated surface exhibited a bright purple color. This purple surface was rubbed with white paper, but no change was observed in the colored state.

[Example 13] Film thickness 8 gm obtained using anodizing solution (5)
A surface-treated product with a white spinel film was treated with a dye (No.
4) Coloring was performed by immersing in an aqueous solution at 60°C containing 5 g/kg for 10 minutes, and then washing with tap water for 10 minutes. After drying, the treated surface exhibited a bright yellow color. This yellow surface was rubbed with white paper, but no change was observed in the colored state.

[Example 14] Film thickness Bgm obtained using anodizing solution (5)
A surface-treated product with a white spinel film was treated with a dye (No.
5) Coloring was performed by immersing the sample in a 90°0(7) aqueous solution containing 2.5 g/l for 5 minutes, and then washing with tap water for 10 minutes. After drying, the treated surface exhibited a light green color.

When this green surface was rubbed with white paper, no change was observed in the coloring state.

[Example 15] Film thickness 9 pL obtained using anodizing solution (6)
A surface-treated product with a white spinel film of m
o6) After being immersed in an aqueous solution at 60°C containing 5 g/kg for 10 minutes for coloring treatment, it was washed with tap water for 10 minutes. After drying, the treated surface exhibited a bright gray color. This gray surface was rubbed with white paper, but no change was observed in the colored state.

1 [Example 16] Regarding the test pieces subjected to the coloring treatment in Examples 1 to 15 J
As a result of a salt spray corrosion resistance test according to ISZ2371, it was found that these colored products had about half the corrosion adhesion caused by the salt water spray test when compared to the respective anodized products (uncolored products). It was done. In other words, it was confirmed that the coloring treatment not only improves surface decoration but also improves corrosion resistance.

Patent applicant: Ube Industries Co., Ltd. Agent: Patent attorney: Yanagawa Bokuto 2

Claims (1)

[Claims] ■. A method for coloring magnesium or its alloy, which comprises forming an aluminum oxide-containing film on the surface of magnesium or its alloy, and then coloring the film with an alumite coloring dye. 2. The method for coloring magnesium or its alloy according to claim 1, wherein the aluminum oxide-containing film formed on the surface of the magnesium or its alloy is a spinel film. Claim 2, characterized in that the spinel film formed on the surface of 3° magnesium or its alloy is an anodized film obtained by anodizing the surface.
Method for coloring magnesium or its alloy as described in Section 1. 4゜The surface of magnesium or its alloy is anodized using one or two compounds selected from the group consisting of aluminates, alkali hydroxides, and further boron compounds, carboxylates, phenols, sulfates, and iodine compounds. 4. The method for coloring magnesium or its alloy according to claim 3, wherein the method is carried out using an aqueous anodic diluting solution prepared by dissolving the above. 5゜The anodizing treatment liquid is
0 to 300 g of aluminate, 0.5 to 20 moles of alkali hydroxide per 4411 moles of the aluminate, and 20 to 200 g of a boron compound, 2 to 80 g of carvonebutyric PA,
One or two or more selected from 2 to 50 g of phenols, 2 to 50 g of sulfates, and 5 to 70 g of iodine compounds.
5. The method for coloring magnesium or its alloy according to claim 4, wherein the anodizing solution is obtained by dissolving -.