JPH0631472B2 - Aluminum metal surface treatment agent with oxide film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention provides a surface portion of an oxide-based aluminum-based metal, such as aluminum or an alloy containing aluminum, which has an oxide coating and is provided with color resistance and weather resistance. The present invention relates to an aluminum-based metal surface treatment agent having an oxide film, which produces an excellent opaque white to off-white substance.

(b) Conventional technology Recently, due to changes in lifestyle and taste, it is required to color semi-finished aluminum-based products used in building materials, nameplates, decorative items, daily necessities or vehicles in pastel colors. In particular, in the fields of daily necessities, decorations, vehicles and building materials, pastel-colored aluminum-based metal products are strongly demanded because they give the viewer a gentle and warm feeling.

By the way, in order to color the aluminum-based metal semi-finished product in a pastel color, first,
It is necessary to color the base opaque white to gray white, and conventionally, the following surface treatment method has been proposed as a method for coloring an aluminum based metal semi-finished product to opaque white to gray white.

That is, a semi-finished aluminum-based product having an anodized film is immersed in or electrolyzed in a solution containing at least one salt of calcium salt, magnesium salt, zinc salt and aluminum salt and sulfuric acid, and then this treatment is performed. It is immersed in or electrolyzed in a solution containing at least one substance that reacts with the product from the salt in the fine pores of the anodic oxide film to form a white to off-white compound (JP-A-60). -197897).

(c) Problems to be Solved by the Invention However, this method is a method for coloring a semi-finished aluminum-based metal product having an anodic oxide film to white or off-white through the above steps, and is obtained by this method. The opaque white to gray-white film does not adhere well to the anodized film on the aluminum-based metal.Therefore, after the anodized film is colored, it may be washed with water, dried, or sealed during the steps such as (a). ) There are problems such as film destruction (film loss) and (b) decoloring at the time of sealing, and (c) peeling of the film after sealing, etc., and white to grayish white obtained using these metal salts The coating lacks denseness, has poor weather resistance, and has a fatal defect that the white or gray-white coating has a small refractive index of a coloring component and a low whiteness.

Further, the surface treatment agent used in the above steps cannot uniformly color the anodic oxide coating of the aluminum-based metal, causing color unevenness, which is not practical.

(d) Means for Solving Problems The present inventors have conducted extensive studies for many years in order to solve the above problems all at once.

As a result, when coloring the oxide film part of the aluminum-based metal semi-finished product having the oxide film to opaque white to grayish white, in the obtained opaque white to grayish white film, its film destruction (film loss) and sealing In order to prevent the occurrence of problems such as decolorization at the time, further peeling of the film after sealing, and the like, first, at least one selected from poorly soluble alkaline earth metal salts, aluminum salts, zinc salts or lead salts. Is used to forcibly dissolve this using alums or alums and ammonia, and then immersing an aluminum-based metal having an oxide film in this solution (treatment solution) By electrolyzing the aluminum-based metal having an oxide film in the liquid, the oxide film portion of the aluminum-based metal is colored opaque white to gray white, and then, It found that it should Sealing by 2 Danfuana preliminary sealing and the sealing has been led to completion of the present invention.

That is, the first invention of the present application has at least one hardly soluble metal salt selected from alums, an organic polar solvent and a sparingly soluble alkaline earth metal salt, aluminum salt, zinc salt or lead salt as an essential component. And a surface treatment agent for an aluminum-based metal having an oxide film.

In addition, the second invention of the present application has at least one hardly soluble metal salt selected from alums, organic polar solvents, chelate compounds and alkaline earth metal salts, aluminum salts, zinc salts or lead salts as an essential component. Which is characterized by surface treatment of an aluminum-based metal having an oxide film.

Further, the third invention of the present application is at least one kind of sparingly soluble selected from alums, organic polar solvents, chelate compounds, ammonia and sparingly soluble alkaline earth metal salts, aluminum salts, zinc salts or lead salts. It is characterized by a surface treatment agent for an aluminum-based metal having an oxide film, which contains a metal salt as an essential component.

Hereinafter, first, the first invention of the present application will be described in detail.

The alums used in the present invention are soluble in a mixed solution of water and an organic polar solvent described below, and are at least selected from the poorly soluble alkaline earth metal salts, aluminum salts, zinc salts or lead salts described below. There is no particular limitation as long as it promotes the solubility of one kind of sparingly soluble metal salt.

Specific examples of the above alums include potassium aluminum sulfate (potassium alum), sodium aluminum sulfate (sodium alum), rubidium aluminum sulfate, cesium aluminum sulfate, thallium aluminum sulfate, ammonium aluminum sulfate (ammonium alum), potassium gallium sulfate. , Gallium ammonium sulfate, indium ammonium sulfate,
Titanium cesium sulfate, potassium vanadium sulfate, potassium manganese sulfate, potassium rhodium sulfate, potassium chromium sulfate, chromium cesium sulfate, ammonium chromium sulfate, ammonium manganese sulfate, ammonium iron sulfate,
Examples include potassium iron sulfate, ammonium cobalt sulfate, potassium cobalt sulfate, and the like.

Further, the organic polar solvent used in the present invention, as well as promoting the solubility of at least one hardly soluble metal salt selected from poorly soluble alkaline earth metal salts, aluminum salts, zinc salts or lead salts described below. , Which stabilizes an opaque white or off-white substance produced by hydrolysis thereof, but is not particularly limited as long as it is a water-soluble polar solvent, and specifically, for example, methanol, ethanol, etc. Lower alcohols such as acetone, ketones such as methyl ethyl ketone and diethyl ketone, ethers such as ether and diethyl ether, amines such as methylamine, ethylamine, monoethanolamine, diethanolamine and triethanolamine, ethylene glycol,
Examples thereof include glycols such as diethylene glycol, propylene glycol and polyethylene glycol, glycerin, tetrahydrofuran, dimethylformamide and dimethylacetamide.

Specific examples of at least one hardly soluble metal salt selected from poorly soluble alkaline earth metal salts, aluminum salts, zinc salts or lead salts include magnesium oxide, magnesium ammonium phosphate, magnesium hydroxide, magnesium phosphate, Calcium hydroxide, calcium sulfate, strontium hydroxide, strontium chromate, barium metasilicate, barium fluoride, barium phosphate-barium hydrogen carbonate, barium carbonate, barium hexafluorosilicate, barium oxalate, aluminum fluoride, aluminum iodide, Examples thereof include aluminum phosphate, aluminum hydroxide, aluminum oxalate, magnesium tetroxide dialuminum tetraoxide, barium tetroxide dialuminum, zinc oxide, zinc phosphate, zinc carbonate, zinc cyanide, lead sulfate and lead carbonate.

The surface treatment agent for an aluminum-based metal having an oxide film of the present invention (hereinafter referred to as a surface treatment agent) is a salt of the alum and an organic polar solvent and a sparingly soluble alkaline earth metal, aluminum salt, zinc salt or An aqueous solution in which at least one hardly soluble metal salt selected from lead salts is used as an essential component, and water and, if desired, a pH adjusting agent are added thereto.

The concentration of the alums is 0.1 to 150 g /
, Particularly preferably 5 to 100 g /, and if the amount is less than 0.1 g /, the concentration may be too low and the solubility of the sparingly soluble alkaline earth metal salt may be poor and sufficient effects may not be obtained. On the contrary, if it exceeds 150 g /, the effect is limited, and it is rather uneconomical, which is not preferable.

The concentration of the organic polar solvent is 1 to 50% by volume.
Is preferred.

That is, in the surface treatment agent of the present invention, by the alums described above, the solubility of at least one hardly soluble metal salt selected from a poorly soluble alkaline earth metal salt, an aluminum salt, a zinc salt or a lead salt, By improving the dispersibility and immersing an aluminum-based metal having an oxide film in this treatment liquid, or by electrolyzing the aluminum-based metal having an oxide film in this treatment liquid, the surface of the aluminum-based metal having excellent characteristics It is possible to form an off-white dense film, but if the concentration of the organic polar solvent is less than 1% by volume, the effect may be too thin to obtain a sufficient effect. On the contrary, if it exceeds 50% by volume, the concentration may increase. It is preferable that it becomes too high and affects the solubility of at least one hardly soluble metal salt selected from alums and poorly soluble alkaline earth metal salts, aluminum salts, zinc salts or lead salts. There.

And the 1st invention of this application requires the above-mentioned alum, an organic polar solvent, and at least 1 kind of sparingly soluble metal salt chosen from a salt of a sparingly soluble alkaline earth metal, an aluminum salt, a zinc salt, or a lead salt. As a component, water and, if desired, a pH adjusting agent are added thereto, and the pH of the surface treating agent is set to 0.5 to 5.5, particularly 1.5 to 4. If the pH is less than 0.5, the acidity becomes too high and the film may be destroyed.
Alkaline earth metal salt dissolved when the pH exceeds 5.5,
The surface treatment agent becomes cloudy during storage or handling due to hydrolysis of at least one kind of sparingly soluble metal salt selected from aluminum salt, zinc salt or lead salt, and aluminum metal having an oxide film. Is immersed in a surface treatment agent or when an aluminum-based metal having an oxide film is electrolyzed in the surface treatment agent, a salt of an alkaline earth metal produced by hydrolysis or the like, an aluminum salt, a zinc salt or a lead salt is selected. It is not preferable because the particles of the product such as the oxide of at least one hardly soluble metal salt may become too large to penetrate into the surface of the aluminum-based metal, or a dense film may not be obtained. .

And, in this pH range, a salt of an alkaline earth metal, an aluminum salt, a zinc salt or a hydrated oxide of at least one sparingly soluble metal salt selected from a lead salt is polymerized, which is colorless and transparent or slightly turbid. It is understood as a certain hydrosol.

The pH adjusting agent, sulfuric acid, inorganic acids such as phosphoric acid, acetic acid, citric acid, succinic acid, gluconic acid, glycine, malonic acid, oxalic acid, organic acids such as formic acid, hydroxides of alkali metals, carbonates Alternatively, bicarbonates, ammonia, alkali metal salts of organic acids and the like can be mentioned.

The alkali metal salts of these acids or bases or organic acids are 1
One type may be used, or two or more types may be used in combination, and the combined use may be more effective in some cases.

Next, the second invention of the present application will be described in detail.

The second invention of the present application relates to an improvement of the first invention.

That is, alums, organic acid polar solvents, chelate compounds and sparingly soluble alkaline earth metal salts, aluminum salts,
A surface treatment agent for an aluminum-based metal having an oxide film, which contains at least one hardly soluble metal salt selected from a zinc salt or a lead salt as an essential component.

The present invention is obtained by adding a chelate compound to the first invention, and the requirements other than the addition of the chelate compound are the same as those of the first invention.

Then, the chelate compound used in the present invention is the stability of at least one sparingly soluble metal salt selected from alums and alkaline earth metal salts, aluminum salts, zinc salts or lead salts in the surface treatment agent, and the surface thereof. When the above-mentioned aluminum-based metal is immersed in the treatment agent, or when the above-mentioned aluminum-based metal is electrolyzed in the surface treatment agent, it is selected from the alkaline earth metal salt, aluminum salt, zinc salt or lead salt produced at the surface portion thereof. To stabilize the hydrosol of the product from at least one poorly soluble metal salt.

Further, it facilitates the binding between the oxide film of the aluminum-based metal having an oxide film and the product of at least one sparingly soluble metal salt selected from alkaline earth metal salts, aluminum salts, zinc salts or lead salts. It has an action.

Specific examples of the chelate compound include ethylenediaminetetraacetic acid and its sodium salt, trans-1,
2-cyclohexanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminediacetic acid, 3,6-dioxa-1,8-octanediaminetetraacetic acid, N- (2-hydroxyethyl) ethylenediaminetriacetic acid, N- (2-hydroxyethyl) Amino compounds having two or more amine groups in one molecule such as iminodiacetic acid, polyaminocarboxylic acids such as triethylenetetramine hexaacetic acid, diamines such as ethylenediamine, triamines such as diethylenetriamine, triethanolamine and triethylenetetramine.
Examples include polybasic acids such as ethyl acetoacetate, nitrilotriacetic acid, formalin, oxalic acid, maleic acid, tartaric acid, malic acid, citric acid, succinic acid, gluconic acid or glycine, and soluble metal salts thereof.

Among these, a chelate compound insoluble in water is also included, but it is dissolved by adding an organic polar solvent, that is, in a mixture of water and an organic polar solvent.

The concentration of the chelate compound used depends on the type and concentration of at least one hardly soluble metal salt selected from alums, organic polar solvents and alkaline earth metal salts, aluminum salts, zinc salts or lead salts, Generally, a range of 0.1 to 50 g / is preferable, and 0.1 g /
If the amount is less than 50 g / g, the effect is poor, and if it exceeds 50 g / g, the effect is limited.

Further, the third invention of the present application will be described in detail.

A third invention of the present application relates to an improvement of the second invention.

That is, alums, organic polar solvents, chelate compounds, ammonia and sparingly soluble alkaline earth metal salts, aluminum salts, zinc salts or lead salts as an essential component, at least one sparingly soluble metal salt, A surface treatment agent for an aluminum-based metal having an oxide film.

The present invention is obtained by adding ammonia to the above-mentioned second invention, whereby at least one refractory metal selected from refractory alkaline earth metal salts, aluminum salts, zinc salts or lead salts is used. The solubility of the salt is further improved, and by adding ammonia in this manner, at least a salt of a poorly soluble alkaline earth metal having a poorer solubility, an aluminum salt, a zinc salt or a lead salt is selected. The solubility of a kind of hardly soluble metal salt is further improved, and other requirements are the same as those of the second invention.

The ammonia used in the present invention includes ammonia, aqueous ammonia, ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium phosphate, ammonium citrate, hydroxylammonium sulfate, ammonium hydrogen fluoride, ammonium chlorate, ammonium perchlorate, and fluorine. Ammonium iodide, ammonium iodide, ammonium iodate, ammonium periodate,
Ammonium sulfide, ammonium pentasulfide, ammonium sulfite monohydrate, ammonium hydrogen sulfite, ammonium hydrogen sulfate, ammonium thiosulfate, ammonium amidosulfate, ammonium selenite, ammonium selenite, ammonium phosphate, diammonium hydrogen phosphate,
Ammonium dihydrogen phosphate, ammonium cyanide, ammonium cyanate, ammonium thiocyanate, ammonium carbonate, ammonium hydrogen carbonate, ammonium hydrogen carbamate, ammonium metaborate, ammonium tetraborate, ammonium metavanadate (V),
Examples thereof include ammonium chromate and ammonium dichromate.

And this ammonia may use 1 type, and may use 2 or more types together if desired.

By the way, the reason why the addition of ammonia in the surface treatment agent improves the solubility and dispersibility of at least one sparingly soluble metal salt selected from sparingly soluble alkaline earth metal salts, aluminum salts, zinc salts or lead salts. Although it is not clear, the ammonium ion forms a complex by binding with at least one poorly soluble metal salt selected from the alkaline earth metal salt, aluminum salt, zinc salt or lead salt, whereby the alkaline earth metal is formed. It is understood that at least one sparingly soluble metal salt selected from the salt, the aluminum salt, the zinc salt or the lead salt is stabilized and the solubility and dispersibility are improved.

The concentration of the above-mentioned ammonia varies depending on the type and combination of alums, organic polar solvents, chelate compounds or ammonia used, etc.
It is appropriately selected from the range of 100 g /, preferably 3 to 50 g /.

In the present invention, the aluminum-based metal having an oxide film is formed by chemically or electrochemically (anodic oxidation) forming an oxide film on the surface of aluminum or an alloy containing aluminum. The above-mentioned products are preferable because a white to off-white oxide film having uniform and more excellent properties can be obtained.

Then, in order to form an anodic oxide film on the aluminum-based metal, a known anodic oxidation method is adopted.

For example, sulfuric acid, phosphoric acid, inorganic acids such as chromic acid, oxalic acid, paraphenolsulfonic acid, sulfosalicylic acid, organic acids such as malonic acid or sodium hydroxide,
An anodic oxide film is formed by electrolysis by direct current, alternating current, pulse, PR wave or AC / DC superposition method in an aqueous solution of trisodium phosphate or the like.

Next, use examples of the surface treatment agent of the present invention will be described below.

In coloring the surface of the aluminum-based metal having an oxide film in white to grayish white, the surface treatment agent is charged in a treatment tank, and if necessary, temperature is adjusted with water and / or an organic polar solvent, and the temperature of the surface treatment agent is adjusted. Is usually room temperature to 75
C., preferably 40 to 70.degree. C., and an aluminum-based metal having an oxide film is usually added to this solution for 10 seconds to 30 seconds.
Minute, preferably 1 minute to 20 minutes, or electrolyzing under normal electrolysis conditions to obtain a white to grayish white dense film having excellent characteristics in a single treatment.

1 to 100 g / a, preferably 5 to 50 g of the obtained aluminum-based metal having an opaque white to off-white film.
After pre-sealing in a g / sodium silicate aqueous solution at a temperature of 90 ° C or higher for 3 minutes or longer, the sealing salt AS (Se
aling SaltAS Sand Co.) etc. sealing agent 1-50 g /
In this aqueous solution, the main sealing may be performed for 5 minutes or more under the condition of the temperature of 90 ° C. or more.

(e) Action The present invention has the above-mentioned constitution, and contains alum and an organic polar solvent or alum and an organic polar solvent and ammonia in the surface treatment agent, so that it is a poorly soluble alkaline earth metal. It is possible to improve the solubility or dispersibility of at least one hardly soluble metal salt selected from salt, aluminum salt, zinc salt or lead salt, and moreover, alkaline earth metal salt, aluminum salt, zinc salt or At least one kind of poorly soluble metal salt selected from lead salts, changes in pH,
In other words, a fine alkaline earth metal salt, aluminum salt, zinc salt, or lead salt is hydrolyzed by immersing an aluminum-based metal having an oxide film or by electrolyzing the aluminum-based metal in a surface treatment agent to change the pH. When a hydrosol of a product from at least one poorly soluble metal salt selected from the above, the organic polar solvent is at least one selected from alkaline earth metal salts, aluminum salts, zinc salts or lead salts. The water molecules coordinated to the product from the sparingly soluble metal salt are deprived of water to promote hydrolysis, thereby continuously producing a fine hydrosol of the product on the surface of the aluminum-based metal. , Precise,
Moreover, it has the function of forming a film with excellent adhesion.

(f) Examples Hereinafter, the present invention will be described in detail based on Examples, but the present invention is not limited thereto.

Examples 1 to 7 Table 1 shows the compositions of the surface treatment agents of Examples 1 to 7.

Examples 8 to 14 Table 2 shows the composition of each surface treatment agent of Examples 8 to 14.

Examples 15 to 31 Table 3 shows the composition of each surface treatment agent of Examples 15 to 31.

Comparative Example 1 The following aluminum plate was treated with an aqueous solution (30 ° C.) of calcium acetate 30 g / and sulfuric acid 0.5 g / at an alternating voltage of 20.
Electrolysis was performed for 20 minutes at V to obtain an opaque white film on the surface of the aluminum plate.

Comparative Example 2 The following aluminum plate was dipped in an aqueous solution of aluminum sulfate 50 g / and sulfuric acid 0.5 g / (60 ° C.) for 20 minutes, washed with water, and then dipped in an aqueous solution of phosphoric acid 20 g / (40 ° C.) for 20 minutes to make aluminum. An opaque white film was obtained on the surface of the plate.

Comparative Example 3 The following aluminum plate was treated with an aqueous solution (25 ° C.) of zinc sulfate 15 g / and sulfuric acid 0.5 g / at an alternating voltage of 20 V for 1 hour.
After electrolysis for 0 minutes and washing with water, electrolysis was performed with an aqueous solution of oxalic acid of 20 g / 25 ° C. for 20 minutes at a DC voltage of 15 V to obtain an opaque white film on the surface of the aluminum plate.

Comparative Example 4 The following aluminum plate was immersed in an aqueous solution of calcium acetate 20 g / and sulfuric acid 0.5 / (30 ° C.) for 30 minutes, washed with water, and then washed with an aqueous solution of sulfuric acid 20 g / (35 ° C.) at an AC voltage of 20 V for 20 minutes. Electrolysis was performed to obtain an opaque white film on the surface of the aluminum plate.

Comparative Example 5 The following aluminum plate was treated with an aqueous solution (25 ° C.) containing 15 g of calcium acetate / 0.5 g of sulfuric acid / DC voltage 15
Electrolyze at V for 5 minutes, wash with water, and then use 30g / sodium phosphate.
It was immersed in the aqueous solution (40 ° C.) for 20 minutes to obtain an opaque white film on the surface of the aluminum plate.

Comparative Example 6 The following aluminum plate was treated with an aqueous solution (30 ° C.) of magnesium nitrate 30 g / and sulfuric acid 1 g / and an AC voltage of 20 V was applied.
At 10 ° C. for 10 minutes, washed with water, and immersed in an aqueous solution of sodium carbonate (30 g / 40 ° C.) for 20 minutes to obtain an opaque white film on the surface of the aluminum plate.

Comparative Example 7 An aluminum plate shown below was treated with an aqueous solution (40 ° C.) of magnesium nitrate 20 g / and sulfuric acid 1 g / at an alternating voltage of 20 V.
At 10 ° C. for 10 minutes, washed with water, and immersed in an aqueous solution of sodium carbonate (30 g / 40 ° C.) for 20 minutes to obtain an opaque white film on the surface of the aluminum plate.

A white to grayish white coloring test was carried out using the above-mentioned respective examples.
The results obtained under the conditions shown in the table and the results of each comparative example are
Each is shown in the table.

By the way, in the above example, after the oxide film portion of the following aluminum plate was colored opaque white to grayish white, it was presealed for 5 minutes at a temperature of 98 ° C. in an aqueous solution of water glass 15 g / min, and then the sealing salt AS was used. (Sealing SaltAS
(Manufactured by Sand Co.) in an aqueous solution of 3.5 g / temperature 98 ° C.
The main sealing was performed for 10 minutes.

The anodic oxide film used in each of the above-mentioned Examples and Comparative Examples was prepared by subjecting a pure aluminum plate to pretreatment such as normal degreasing, and then sulfuric acid concentration 180 g /, bath temperature 20 ° C., current density 1.5 A /. It was obtained by direct current electrolysis for 20 minutes under the condition of dm ² .

In this case, the thickness of the anodized film was 10 μm.

As shown in the results of the color tone in Table 4, at least one hardly soluble metal salt selected from alum, an organic polar solvent and a sparingly soluble alkaline earth metal salt, aluminum salt, zinc salt or lead salt is an essential component. The surface treatment agent of the present invention, that is, the one in which the anodized film was colored white by the surface treatment agent of the first invention of the present application was uniform, and almost no color unevenness was observed.

In addition, this white film did not cause film destruction during the subsequent steps such as washing with water and drying, and did not cause problems such as decolorization by the sealing agent and film peeling after sealing.

The second invention of the present application, that is, the one obtained by adding the chelate compound to the surface treatment agent of the first invention, could be colored more uniformly (white) and was excellent in weather resistance.

In addition, this white film did not cause a problem such as film destruction as in the first invention.

Furthermore, the third invention of the present application is the addition of ammonia to the second invention, whereby at least one selected from the sparingly soluble alkaline earth metal salts, aluminum salts, zinc salts or lead salts. It was confirmed that the solubility of the hardly soluble metal salt can be further improved and an excellent white film can be obtained.

Further, this white film did not cause a problem such as film destruction as in the first invention.

On the other hand, in each of the comparative examples, color unevenness is large and lacks in practicality, and also good results are not obtained with respect to weather resistance, and further, film destruction occurs during steps such as washing with water and drying. However, problems such as discoloration by the sealing agent and peeling of the film after sealing occurred.

(g) Effect of the invention The surface-treating agent of the present invention is immersed in an aluminum-based metal having an oxide film, or the pH of the solution is changed only by electrolysis in the site, that is, the part where the pH is changed, that is, the oxide film. Alkaline earth metal salt, aluminum salt, on the surface or inside,
At least one sparingly soluble metal salt selected from zinc salts or lead salts is hydrolyzed, whereby an alkaline earth metal salt,
A metal oxide of at least one hardly soluble metal salt selected from an aluminum salt, a zinc salt or a lead salt is used to color the above coating part white or grayish white, and a salt of an insoluble alkaline earth metal, an aluminum salt. Since at least one kind of sparingly soluble metal salt selected from zinc salt or lead salt is used, problems such as film destruction after coloring, decoloration with a sealing agent and film peeling after sealing do not occur. It has the effect of forming a white or gray-white film that is uniform and dense, has excellent weather resistance and durability.

Claims (15)

[Claims] 1. An oxide film comprising an alum, an organic polar solvent and at least one hardly soluble metal salt selected from a poorly soluble alkaline earth metal salt, an aluminum salt, a zinc salt or a lead salt as an essential component. An aluminum-based metal surface treatment agent. 2. The concentration of alums is 0.1 to 150 g /
The surface treatment agent for an aluminum-based metal having an oxide film according to claim 1. 3. The surface-treating agent for an aluminum-based metal having an oxide film according to claim 2, wherein the concentration of alums is 5 to 100 g /. 4. The surface treating agent for an aluminum-based metal having an oxide film according to claim 1, wherein the concentration of the organic polar solvent is 1 to 50% by volume. 5. An essential component is at least one sparingly soluble metal salt selected from alums, organic polar solvents, chelate compounds and sparingly soluble alkaline earth metal salts, aluminum salts, zinc salts or lead salts. A surface treatment agent for an aluminum-based metal having an oxide film. 6. The concentration of alums is 0.1 to 150 g /
A surface treatment agent for an aluminum-based metal having an oxide film according to claim 5. 7. The surface-treating agent for an aluminum-based metal having an oxide film according to claim 6, wherein the concentration of alums is 5 to 100 g /. 8. A surface treatment agent for an aluminum-based metal having an oxide film according to any one of claims 5 to 7, wherein the concentration of the organic polar solvent is 1 to 50% by volume. 9. The chelate compound is a polyaminocarboxylic acid, a polybasic acid, or an amine compound having two or more amino groups in one molecule.
An aluminum metal surface treatment agent having an oxide film according to any one of items. 10. An essential component is at least one hardly soluble metal salt selected from alums, organic polar solvents, chelate compounds, ammonia, and sparingly soluble alkaline earth metal salts, aluminum salts, zinc salts or lead salts. And a surface treatment agent for an aluminum-based metal having an oxide film. 11. The concentration of alums is 0.1 to 150 g.
The surface treatment agent for an aluminum-based metal having an oxide film according to claim 10, which is /. 12. The concentration of alums is 5 to 100 g /
The aluminum-based metal surface treatment agent having an oxide film according to claim 11. 13. The concentration of the organic polar solvent is 1 to 50% by volume.
A surface treatment agent for an aluminum-based metal having an oxide film according to any one of claims 10 to 12, which is 14. The oxide film according to any one of claims 10 to 13, wherein the chelate compound is a polyaminocarboxylic acid, a polybasic acid or an amine compound having two or more amino groups in one molecule. A surface treatment agent for aluminum metal. 15. The surface treatment agent for an aluminum-based metal having an oxide film according to claim 10, wherein the ammonia is ammonia, aqueous ammonia, or an ammonium salt.