JP6557984B2 - Aluminum or aluminum alloy sealing method and sealing device - Google Patents

Description

  The present invention relates to an aluminum or aluminum alloy sealing treatment method and a sealing treatment apparatus for sealing pores formed on an anodized surface of aluminum or aluminum alloy. The present invention also relates to an aluminum substrate that has been sealed by this sealing treatment method. The aluminum or aluminum alloy sealing treatment method and sealing processing apparatus of the present invention can be used, for example, as an aluminum sash surface alumite treatment and boehmite treatment.

Aluminum or aluminum alloys used for general building materials and equipment are usually subjected to anodizing treatment because they corrode, that is, dissolve and generate dust during long-term use. In addition, since the inner surface of a component used in a dry etching apparatus or the like must be insulative, it is anodized to impart plasma resistance and gas corrosion resistance.
Furthermore, with anodization treatment, aluminum is eluted from the bottom of the pores formed by anodization treatment, and adsorbed substances are eluted from the treatment solution used in anodization treatment. Hole treatment is applied.

Patent Document 1 describes a basic anodizing method using an oxalic acid solution, a sulfuric acid solution, or a boric acid solution as a method for anodizing an aluminum container.
There are various methods such as steam sealing, hot water sealing, and sealing using a sealing agent for the sealing processing performed subsequent to the anodizing treatment, but the method using a sealing agent is mainly used. ing. Various types of sealing agents including nickel acetate are known, and an aluminum base material on which an anodized film is formed in a sealing tank containing an aqueous solution at 70 to 100 ° C. containing these sealing agents. By dipping, sealing treatment is performed (for example, Patent Document 2).
Prior to the solution film sealing treatment, functional materials such as an antibacterial agent are filled in the pores of the anodized film and then sealed to provide functionality. .

JP-A-62-103377 JP 2004-277866 A

  In the above conventional sealing treatment, since the treatment takes a long time, for example, when an antibacterial agent or the like is enclosed in the pores, the enclosed agent is diffused and eluted as an impurity in the treatment solution; As hydration progresses and the pores narrow, the amount of encapsulated decreases. In addition, the long processing time affects productivity and leads to an increase in processing cost.

  The present invention solves the above-described conventional problems, has a small amount of impurity elution, and can seal only the vicinity of the pore surface in a shorter time than in the past, or a sealing treatment method of aluminum or aluminum alloy, It aims at providing the processing apparatus for it. Another object of the present invention is to provide an aluminum substrate that has been sealed by this sealing treatment method.

  As a result of repeated studies by the present inventor, it is possible to efficiently perform the sealing treatment in a short time by using a solution having a redox potential within a predetermined range as the treatment liquid during the sealing treatment. It has been found that a sealed surface can be formed.

  The present invention has been achieved based on such findings, and the gist thereof is as follows.

[1] An aluminum or aluminum alloy sealing treatment method in which pores are sealed in a sealing treatment solution with respect to aluminum or aluminum alloy having pores formed on the surface by anodization, A sealing treatment method for aluminum or an aluminum alloy, wherein the oxidation-reduction potential of the sealing treatment liquid is +1.5 to +3.5 V.

[2] In [1], the sealing treatment solution contains one or more selected from the group consisting of phosphoric acid, oxalic acid, acetic acid, sulfuric acid, boric acid and hydrofluoric acid, or aluminum or Method for sealing aluminum alloy.

[3] In [1] or [2], the oxidation-reduction potential of the sealing treatment solution is increased by +1 by any one or more of electrolytic treatment, addition of an oxidizing agent, and addition of a solution having a high oxidation-reduction potential. Adjusting to 5 to +3.5 V, a method for sealing aluminum or aluminum alloy.

[4] In any one of [1] to [3], any one or more of the circulation treatment of the sealing treatment liquid, the transient addition of the sealing treatment liquid, and the blowing of gas into the sealing treatment liquid The method for surface treatment of aluminum or aluminum alloy, wherein the oxidation-reduction potential of the sealing treatment liquid is adjusted to +1.5 to +3.5 V by the above method.

[5] In any one of [1] to [4], the temperature of the sealing treatment liquid is 60 to 90 ° C., the acid concentration is 350 to 1,600 g / L, and the oxidizing agent concentration is 2 to 15 g / L. A surface treatment method for aluminum or an aluminum alloy, wherein the sealing treatment is performed under non-energization.

[6] The aluminum or aluminum alloy sealing treatment method according to any one of [1] to [5], wherein the sealing treatment liquid contains sulfuric acid and persulfuric acid.

[7] The sealing treatment of aluminum or aluminum alloy according to [6], wherein the sealing solution has a sulfuric acid concentration of 350 to 1,600 g / L and a persulfuric acid concentration of 2 to 15 g / L. Method.

[8] The aluminum or the electrolyte according to [6] or [7], wherein the sulfuric acid-containing sealing treatment solution is circulated and circulated through a persulfuric acid generating electrolytic cell to be electrolyzed to contain persulfuric acid. Method for sealing aluminum alloy.

[9] The aluminum or aluminum alloy sealing treatment method according to [6] or [7], wherein the sealing treatment liquid is a mixture of sulfuric acid and hydrogen peroxide to produce persulfuric acid. .

[10] A sealing treatment method for aluminum or aluminum alloy according to [6] or [7], wherein the sealing treatment solution generates persulfuric acid by mixing sulfuric acid and ozone.

[11] The sealing process for aluminum or aluminum alloy according to any one of [1] to [10], wherein the aluminum or aluminum alloy is an aluminum base material or aluminum alloy base material having a thickness of 1 mm or more. Method.

[12] An aluminum base material that is sealed by the aluminum or aluminum alloy sealing method according to any one of [1] to [11].

[13] An aluminum or aluminum alloy sealing apparatus having sealing means for sealing aluminum or an aluminum alloy having pores formed on the surface by an anodizing treatment in a sealing treatment liquid, the sealing process An aluminum or aluminum alloy sealing apparatus comprising means for adjusting the oxidation-reduction potential of a treatment liquid to +1.5 to +3.5 V.

[14] An aluminum or aluminum alloy comprising: a treatment tank for storing a sulfuric acid-containing treatment liquid; and an electrolytic cell for generating persulfuric acid in which the sulfuric acid-containing treatment liquid in the treatment tank is circulated. Sealing device.

  According to the present invention, in the sealing treatment of the anodized film of aluminum or aluminum alloy, the elution of impurities can be suppressed, and only the vicinity of the pore surface can be efficiently sealed in a shorter time than before, A good sealing surface can be formed.

It is typical sectional drawing which shows an example of this invention apparatus. 2 is an electron micrograph of the anodized film obtained in Example 1. FIG. 2 is an electron micrograph of the sealing surface obtained in Example 1. FIG. 3 is an electron micrograph of a cross section of the sealing film obtained in Experimental Example 1. FIG.

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

  In the present invention, after anodizing aluminum or an aluminum alloy (hereinafter sometimes referred to as “aluminum substrate” or “aluminum substrate”) to form pores on the surface, In performing the sealing treatment, a sealing treatment liquid having a redox potential of +1.5 to +3.5 V is used as the sealing treatment liquid used for the sealing treatment.

<Action mechanism>
In general, when anodizing aluminum,
Al → Al ³⁺ + 3e ⁻ (1)
According to the reaction, Al ³⁺ is eluted.
The eluted Al ³⁺ reacts with oxygen generated by the water splitting reaction represented by the following formula (2) that occurs in part or in the local battery as an anodic reaction, and becomes Al ₂ O ₃ .
3H ₂ O → 3 (O) + 6H ⁺ + 6e ⁻ (2)

The general reaction of the formulas (1) and (2) is as shown in the following formula (3).
2Al + 3H ₂ O → Al ₂ O ₃ + 6H ⁺ + 12e ⁻ (3)

The anodizing treatment of aluminum is a competitive reaction between Al dissolution of formula (1) and Al oxidation (formation of Al ₂ O ₃ ) of formulas (2) and (3), and finer holes are opened as the Al oxidation rate increases. It becomes possible.

In the Japanese standard JIS H8601-1968 concerning the anodized film of aluminum, a hydration seal is defined as the seal. Further, in the technical standard for anodizing treatment (JIS H9500-1971, JIS H9501-1971), the treatment conditions for pressurized steam sealing or boiling sealing are defined, and in the case of boiling sealing, addition of sealing aid Admits. The prominence of these reactions is that the anhydrous Al ₂ O ₃ produced by anodic oxidation is changed to hydrate (Al ₂ O ₃ .H ₂ O), and the pores are blocked by the volume change. It is.

On the other hand, the sealing treatment in the present invention is based on a completely different concept from the conventional method.
That is, in the present invention, the above-mentioned formula (4) is expressed on the surface of the anodized film that comes into contact with the treatment liquid by immersing the aluminum base material on which the anodized film is formed in an acid solution having a low pH. The reverse reaction of (3) is caused.
Al ₂ O ₃ + 6H ⁺ → 2Al ³⁺ + 3H ₂ O (4)
Simultaneously with the reaction of the above formula (4), the positive reaction of the above formula (3) represented by the following formula (5) occurs together with the Al elution from the aluminum base material existing under the anodized layer. .
Al ³⁺ + 3H ₂ O → Al ₂ O ₃ + 6H ⁺ (5)

That is, the sealing treatment in the present invention is a competitive reaction between the dissolution of Al ₂ O _{3 in} the above formula (4) and the Al oxidation (formation of Al ₂ O ₃ ) in the above formula (5). Although the sealing speed is increased, in such sealing treatment, in the present invention, the oxidation reaction of Al is accelerated by using a sealing treatment liquid having an oxidation-reduction potential of +1.5 V or more. As a result, the sealing speed is increased and the sealing process can be performed efficiently in a short time.
As described above, since the sealing treatment can be performed in a short time, even when the functional material is sealed in the pores of the anodized film, the elution and the decrease in the amount of sealing can be suppressed.
The higher the oxidation-reduction potential of the sealing solution, the better. However, since the oxidation-reduction potential obtained when hydrofluoric acid is used to maximize the oxidation-reduction potential is +3.5 V, the upper limit of the oxidation-reduction potential is +3. .5V. However, when hydrofluoric acid is used, the life of the treatment solution is shortened. Therefore, the oxidation-reduction potential of the sealing treatment solution is preferably +1.7 to +3.0 V as the oxidation-reduction potential by fluorine other than hydrofluoric acid, for example. Preferably, it is +2.0 to + 2.1V.

<Aluminum substrate>
The aluminum substrate to be treated in the present invention is not particularly limited, and examples thereof include pure aluminum and an alloy containing aluminum as a main component and containing a trace amount (for example, 5% by weight or less) of a different element. The thickness of the aluminum substrate is preferably 1 mm or more from the viewpoint of forming a good sealing surface. There is no particular limitation on the upper limit of the thickness of the aluminum substrate.
Prior to the anodic oxidation treatment, the aluminum base material may be subjected to surface treatment such as degreasing treatment, electrolytic polishing, and mirror finishing treatment in advance.

<Anodizing treatment>
In the present invention, the method for forming the anodic oxide film on the aluminum substrate is not particularly limited, but for the following reasons, it is possible to form a good anodic oxide film by suppressing the elution of aluminum. It is preferable to anodize in an anodizing solution of ~ 3.5V.

That is, as described above, the anodizing treatment of aluminum is a competitive reaction between Al dissolution of formula (1) and Al oxidation (formation of Al ₂ O ₃ ) of formulas (2) and (3), and the Al oxidation rate is high. It is possible to make fine holes as much as possible, but if an anodizing solution having a redox potential of +1.5 V or more is used, the oxidation reaction of Al is accelerated. As a result, the aluminum elution amount is suppressed, and a large number of micropores having a pore diameter of 10 nm or less, for example, 6 to 10 nm, are efficiently formed on the surface of the aluminum substrate, resulting in a dense anodized surface in which the micropores are uniformly dispersed. .
The higher the oxidation-reduction potential of the anodizing solution, the better. However, since the oxidation-reduction potential obtained when hydrofluoric acid is used to maximize the oxidation-reduction potential is +3.5 V, the upper limit of the oxidation-reduction potential is +3. .5V. However, when hydrofluoric acid is used, the life of the treatment solution is shortened. Therefore, the oxidation-reduction potential of the anodic oxidation treatment solution is preferably +1.7 to +3.0 V as the oxidation-reduction potential by fluorine other than hydrofluoric acid. Preferably, it is +2.0 to + 2.1V.

  Hereinafter, in the present invention, the present invention will be described by exemplifying the case where anodizing treatment using such anodizing treatment liquid is performed. However, the anodizing treatment according to the present invention is not limited to the above-described anodizing treatment liquid. It is not limited to what uses.

<Anodizing treatment liquid / Sealing treatment liquid>
(Anodizing solution)
As the anodizing treatment solution, any one commonly used for anodizing treatment of aluminum can be used, and the oxidation-reduction potential of these common treatment solutions is adjusted to the above range. Is preferred.

As an anodizing solution, for adjusting the redox potential with respect to an aqueous solution containing one or more acids selected from the group consisting of phosphoric acid, oxalic acid, acetic acid, sulfuric acid, boric acid and hydrofluoric acid. In addition, it is preferable to apply one or more of electrolytic treatment, addition of an oxidizing agent, and addition of a liquid having a high oxidation-reduction potential (hereinafter sometimes referred to as “high ORP liquid”).
For example, ozone, hydrogen peroxide, persulfuric acid, peracetic acid, perboric acid, or the like can be used as the oxidizing agent, and hydrofluoric acid, fluorine, or the like can be used as the high ORP liquid. Can do.
The electrolytic treatment will be described later.

The above-described treatment for adjusting the oxidation-reduction potential of the anodizing treatment liquid can be performed by the following method, for example.
(1) Circulating the treatment liquid between a treatment tank storing a treatment liquid for anodizing (hereinafter sometimes simply referred to as “treatment tank”) and an adjustment tank for adjusting the oxidation-reduction potential. In the adjustment tank, electrolytic treatment, oxidant addition, or high ORP solution is added (circulation treatment).
(2) A treatment liquid having a predetermined oxidation-reduction potential is added to the treatment tank in a transient manner (temporary addition).
(3) A gas such as ozone gas is blown into the treatment liquid in the treatment tank (gas blow).

The anodizing solution is preferably an aqueous solution having an acid concentration of 50 to 300 g / L, particularly 50 to 200 g / L, and an oxidant concentration of 1 to 30 g / L, particularly 2 to 20 g / L. Among these, the acid concentration and the oxidizing agent concentration are appropriately determined according to the type of acid and oxidizing agent used, that is, according to the amount of H ⁺ ions to be generated.
If the acid concentration is lower than the lower limit, no pores are formed even if anodizing is performed, and if the acid concentration is higher than the upper limit, the hole diameter of the formed holes becomes too large.
Also, if the oxidant concentration is lower than the above lower limit, the pore diameter of the formed holes will be excessive, and if it is higher than the above upper limit, the equipment for adjusting the redox potential of the electrolytic cell for persulfuric acid generation described later will be excessive. Or the cost of adding an oxidant is undesirably high.
In addition, in order to prevent dissolution of Al and form the pore surface only by electrolytic treatment by anodization, the pH of the anodizing solution is preferably low, and is about -0.2 to +0.3. Is preferred.

  As the anodizing solution, a solution containing sulfuric acid and persulfuric acid is particularly preferable. The sulfuric acid concentration is 50 to 200 g / L, particularly 75 to 150 g / L, and the persulfuric acid concentration is 2 to 20 g / L, particularly 5 to 15 g. It is preferable to use an / L aqueous solution.

(Sealing treatment liquid)
As the sealing treatment liquid, the same one as the above-described anodizing treatment liquid can be used, but the sealing treatment liquid and the anodizing treatment liquid are not limited to those containing the same acid or oxidizing agent, May be different from each other.
However, in general, after anodizing by applying a voltage in the same treatment tank, after adjusting the components of the treatment liquid as necessary, the energization is stopped and the sealing treatment is performed. In this respect, it is preferable to use one containing the same kind of acid or oxidizing agent.

  The adjustment of the oxidation-reduction potential of the sealing treatment liquid can be performed in the same manner as in the case of the above-described anodization treatment liquid, but the method for adjusting the oxidation-reduction potential of the sealing treatment liquid and the oxidation-reduction of the anodization treatment liquid The method for adjusting the potential may be the same or different.

The sealing treatment liquid is preferably an aqueous solution having an acid concentration of 350 to 1,600 g / L and an oxidant concentration of 2 to 15 g / L, among which the acid concentration and the oxidant concentration are determined depending on the acid used. Depending on the kind of the oxidizing agent, that is, the amount of H ⁺ ions to be generated, it is appropriately determined.
If the acid concentration of the sealing treatment liquid is too low or too high than the above range, the sealing speed will be slow. Further, if the oxidant concentration is too lower than the lower limit, the sealing speed becomes slow, and if it is higher than the upper limit, facilities for adjusting the redox potential such as a persulfuric acid producing electrolytic cell described later become excessive. . Also, the oxidizer cost is high.
In addition, it is preferable that pH of a sealing process liquid is about -0.5--1.0.

  When a sulfuric acid-containing treatment liquid containing persulfuric acid is used as the sealing treatment liquid, the sulfuric acid concentration is 350 to 1,600 g / L, particularly 500 to 1,500 g / L, and the persulfuric acid concentration is 2 to 15 g / L. It is preferable to use an aqueous solution of 5 to 15 g / L.

<Production of persulfuric acid>
The method for adjusting the treatment liquid to +1.5 to +3.5 V by adding persulfuric acid to the anodizing treatment liquid and the sealing treatment liquid (hereinafter simply referred to as “treatment liquid”) containing sulfuric acid is particularly limited. However, the following method can be adopted.
(1) A sulfuric acid solution is introduced into a sulfuric acid electrolysis cell, and electrolytic treatment is performed to generate persulfuric acid.
(2) Persulfuric acid is produced by mixing sulfuric acid and hydrogen peroxide solution.
(3) Mix sulfuric acid and ozone to produce persulfuric acid.

  In the case of the method (2), for example, a sulfuric acid solution having a sulfuric acid concentration of 96 to 98% by weight and a hydrogen peroxide solution having a hydrogen peroxide concentration of 30 to 35% by weight in a volume ratio of 1:35 to 4:30. By mixing within this range, a treatment liquid suitable for the above-described anodizing treatment can be obtained. In addition, by mixing a sulfuric acid solution having a sulfuric acid concentration of 96 to 98% by weight with a hydrogen peroxide solution having a hydrogen peroxide concentration of 30 to 35% by weight in a volume ratio of 1 to 4 to 5 to 1, It is possible to obtain a treatment liquid suitable for the sealing treatment.

  In the case of the above method (3), ozone is added to a sulfuric acid solution having a sulfuric acid concentration of 50 to 200 g / L so that the ozone concentration is 20 ppm or more, for example, 20 to 60 ppm. A suitable treatment liquid can be obtained. In addition, by adding ozone to a sulfuric acid solution having a sulfuric acid concentration of 350 to 1,600 g / L so that the ozone concentration is 5 ppm or more, for example, 5 to 10 ppm, a treatment liquid suitable for the above-described sealing treatment is obtained. Can do.

The persulfuric acid produced when sulfuric acid and hydrogen peroxide are mixed is peroxomonosulfuric acid (H ₂ SO ₅ ), and the concentration of persulfuric acid immediately after mixing is high. Hydrogen oxide must be added repeatedly. There exists a subject that a sulfuric acid concentration falls by the addition. The persulfuric acid produced when ozone is dissolved in sulfuric acid is peroxomonosulfuric acid and peroxodisulfuric acid (H ₂ S ₂ O ₈ ), but their production concentrations are very low. On the other hand, persulfuric acid obtained by electrolyzing sulfuric acid is peroxodisulfuric acid, and although both types of peroxomonosulfuric acid exist over time due to chemical equilibrium, their concentrations are high and sulfuric acid Since the concentration of persulfuric acid can be adjusted without changing the concentration, in the present invention, it is preferable to electrolyze sulfuric acid to produce persulfuric acid. The sulfuric acid concentration of the sulfuric acid-containing treatment liquid to be subjected to electrolysis is approximately the same as the sulfuric acid concentration of the sulfuric acid-containing treatment liquid used in each of the aforementioned steps.

  FIG. 1 is a schematic cross-sectional view showing an example of a sealing treatment apparatus of the present invention provided with such a sulfuric acid electrolysis cell. In this apparatus, the anodizing process prior to the sealing process can be performed in the same processing tank.

A constant temperature heater 2 is provided on the outer periphery of the processing tank 1. In the tank 1, an aluminum substrate 3 whose peripheral part is held by a frame-shaped holder 4 is arranged with the plate surface in the vertical direction. A plate-like cathode 5 made of carbon or the like is disposed facing the surface-treated surface of the aluminum substrate 3. The cathode 5 has substantially the same size as the aluminum substrate 3, and the plate surface is parallel to the aluminum substrate 3. A voltage is applied from the DC power source 6 to the aluminum substrate 3 and the cathode 5.
A stirring means such as an air diffuser for stirring the liquid may be installed in the treatment tank 1.

  The liquid in the processing tank 1 is circulated through the pipe 7, the pump 8, the electrolytic cell 9 and the pipe 10. An electrolytic cell 9 is provided with an anode 9a and a cathode 9b made of diamond electrodes, and a bipolar electrode 9c disposed therebetween. A predetermined current is supplied to the anode 9a and the cathode 9b from the power supply unit, and sulfuric acid is electrolyzed to generate persulfuric acid such as peroxodisulfuric acid.

For the anodization and subsequent sealing treatment, the apparatus shown in FIG. 1 is used to obtain a sulfuric acid-containing treatment solution having a predetermined sulfuric acid and persulfuric acid concentration. In addition, the concentration of sulfuric acid and persulfuric acid in the sulfuric acid-containing treatment solution may be adjusted, and the anodizing treatment may be followed by a sealing treatment in the same treatment tank under non-energization, using the apparatus shown in FIG. After the anodizing treatment, the sealing treatment may be performed using a sealing treatment apparatus having the same configuration except that the cathode 5 and the power source 6 are omitted. At this time, the electrolytic cell may be shared by the sealing treatment tank and the anodizing tank.
When the sealing processing apparatus of the present invention performs only sealing processing, the cathode 5 and the power source 6 can be omitted in FIG.

In the above description, the case where persulfuric acid is generated by electrolytic treatment or oxidation of sulfuric acid is exemplified. However, it is not limited to persulfuric acid, but percarbonate (peroxomonocarbonate (H ₂ CO ₄ )) is produced by electrolytic treatment or oxidation of carbonic acid. Peroxodicarbonate (H ₂ C ₂ O ₆ )) can be produced, and perboric acid can be produced by electrolytic treatment or oxidation of boric acid, and peracetic acid can be produced by electrolytic treatment or oxidation of acetic acid. Both can be used as the anodizing solution and the sealing solution in the present invention.

<Processing conditions>
(Anodizing conditions)
Below, the process conditions of the anodizing process using the above anodizing liquid are demonstrated.

  The temperature during the anodizing treatment (temperature of the treatment liquid) is preferably about 0 to 30 ° C. If this temperature is too low, the treatment time becomes long, and if it is too high, the holes may not be opened.

Applied voltage 10 to 30V, the current density is preferably about 2.5~6A / dm ^2. If the applied voltage and current density are too low, the holes will not be opened and the anodized film may be broken.

  The anodizing treatment time depends on the treatment conditions such as the oxidation-reduction potential, acid concentration, oxidant concentration, applied voltage, etc. of the anodizing solution used (the thickness of the anodized film to be formed). It is adjusted appropriately according to For example, it is preferable to form an anodized film having a thickness of about 50 to 85 μm by anodizing for about 1.5 to 3.0 hours.

(Sealing treatment conditions)
Below, the process conditions of the sealing process of this invention using said sealing process liquid are demonstrated.

The temperature of the sealing treatment liquid is preferably about 60 to 90 ° C. If this temperature is too low, the treatment time will be long, and if it is too high, the anodized film may be dissolved.
Unlike the anodizing treatment, no current is passed between the aluminum substrate and the cathode in the sealing treatment. If an electric current is passed, the anodized film may be dissolved.

The sealing treatment time is appropriately determined to such an extent that the sealing treatment can be performed in a desired state, depending on the treatment conditions such as the oxidation-reduction potential, acid concentration, oxidant concentration, treatment temperature, etc. Under the above conditions, a good sealing surface can be formed by closing the pore surface of the anodized film by a sealing treatment of usually about 3 to 10 minutes.
Here, the degree of the sealing treatment may be expressed as the “sealing degree” as a percentage of the ratio of the pores subjected to the sealing treatment with respect to the pores before the sealing treatment. The degree of sealing is appropriately set in the range of 30 to 100% depending on the use of the aluminum base material.

  In the present invention, prior to this sealing treatment, a paint, an antibacterial agent or other functional material is sealed in the micropores of the anodized film formed by the anodizing treatment, and then the sealing treatment is performed, so that an aluminum base is obtained. A desired function can be imparted to the material.

<Application field>
Although there is no restriction | limiting in particular as an application field of the aluminum base material of this invention which performed the sealing process according to this invention, For example, the following are mentioned.

(1) Aluminum sash By coating the pores of the anodic oxide film formed according to the present invention and then sealing it, a color sash that can maintain the desired color for a long time without any discoloration problem is obtained. be able to.
In the conventional color sash, the paint is applied to the aluminum sash. However, since the paint is applied onto the aluminum oxide on the surface of the aluminum sash, there is a problem that the paint film is discolored or peels with time.
According to the present invention, this problem can be solved.
Further, an antibacterial aluminum sash can be obtained by sealing an antibacterial agent in the pores of the anodized film and then performing a sealing treatment. At this time, the sealing degree can be set to, for example, about 90%, and the radioactivity can be imparted so that the antibacterial agent gradually emerges on the surface.

(2) Plasma parts used in dry etching equipment, etc. Dry etching equipment plasma parts used in semiconductors and liquid crystals are evacuated in the chamber, so if the parts contain impurities, they diffuse into the chamber. As a result, it adheres to the workpiece and leads to product defects.
According to the present invention, the sealing treatment can be reliably performed, and impurity diffusion from inside the pores can be suppressed.

(3) Catalyst support After a catalytic metal is sealed in the pores of the anodized film formed according to the present invention, a good metal-supported catalyst can be obtained by appropriately sealing.
Since the catalyst is a reaction field that causes a chemical reaction, the larger the specific surface area, the better the catalytic ability. For example, platinum (Pt) has been used as a catalyst in many reactions, and Pt nanocolloids have been developed to increase the specific surface area. However, it is difficult to support Pt nanocolloid so as to obtain a large catalytic active surface area. Currently, it is supported on a resin, but the supported amount is 5% or less of the resin surface area.
In accordance with the present invention, the Pt nanocolloid is encapsulated in the pores of an anodized aluminum substrate and slightly sealed so as not to drop into the reaction system (for example, the sealing degree is 10 to 20%). It is possible to make about 30% of the Pt surface, and the catalytic function can be enhanced.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1]
Using the apparatus shown in FIG. 1, an aluminum plate having a purity of 99.85% and a thickness of 2 mm was anodized and then subjected to a sealing treatment. The specifications and conditions of the treatment tank are as follows.

<Treatment tank>
Volume of treatment tank 1: 40L
Size of aluminum plate: 500mm x 500mm x thickness 2mm
Cathode size: 500mm x 500mm x thickness 3mm
Cathode material: Carbon Distance between aluminum plate and cathode: 30 mm
Applied voltage: 20V (constant)
Anodizing solution Sulfuric acid concentration: 100 g / L
Persulfuric acid concentration: 10 g / L
Redox potential: + 2.0V
pH: 0.0
Temperature: 20 ° C
Processing time: 2 hours

<Electrolytic cell for persulfuric acid production>
Cell volume: 0.5L
Anode and cathode: Diamond electrode (diameter 150 mm)
Bipolar membrane material: Same as anode Current density: 50 A / dm ²
Liquid flow rate: 52 L / h

  The sealing treatment was performed under the following conditions using the above-described anodizing bath as it was without applying a voltage. In the sealing treatment, sulfuric acid was additionally added in order to increase the sulfuric acid concentration of the sealing treatment solution as compared with the anodic oxidation treatment.

<Sealing treatment conditions>
Sulfuric acid-containing treatment solution:
Sulfuric acid concentration: 1,200 g / L
Persulfuric acid concentration: 10 g / L
Redox potential: + 2.0V
pH: -1.0
Temperature: 80 ° C
Processing time: 5 minutes

  The persulfuric acid concentration of the treatment liquid was measured by the following method, the oxidation-reduction potential was measured by a voltammetry method, and the pH was measured by a pH meter.

<Persulfuric acid concentration measurement method>
First, the total oxidant concentration contained in the treatment liquid is measured by iodine titration. And the iodometric titration to free l ₂ by adding Kl, determine the amount of l ₂ by titrating the l ₂ with sodium thiosulfate standard solution, the amount of that l _2, and requests oxidant concentration is there. Next, only the hydrogen peroxide concentration was determined by potassium permanganate titration, and the persulfate concentration was determined by iodine titration-potassium permanganate titration.

A 100 g / L sulfuric acid aqueous solution is accommodated in the treatment tank, and the pump 8 and the electrolysis cell 9 are operated so that the persulfuric acid concentration is 10 g / L, the sulfuric acid concentration is 100 g / L, the oxidation-reduction potential is +2.0 V, and the pH is 0.0. After that, the aluminum plate was immersed, a voltage of 20 V was applied between the cathode and the anodization was started at 150 A (6 A / dm ² ), and the anodization was continued for 2 hours. Thereafter, the aluminum plate on which the anodized film was formed was taken out of the treatment tank 1, washed with pure water and dried, and the formed anodized film surface was observed with an electron microscope. An electron micrograph is shown in FIG.

  Subsequently, the aluminum plate was returned to the treatment tank 1 again, and sealing treatment was performed for 5 minutes without applying a voltage under the above-described sealing treatment conditions. Thereafter, the aluminum plate was taken out from the treatment tank 1, washed with pure water and dried, and the sealed surface was observed with an electron microscope. An electron micrograph is shown in FIG.

As shown in FIG. 2, a good porous anodic oxide film in which uniform and dense pores were formed was formed by anodic oxidation. In addition, it was 70 micrometers when the film thickness of this anodic oxide film was measured with the electron microscope.
Further, as shown in FIG. 3, the pores of the anodized film were sealed with a sealing degree of about 100% by the sealing treatment, and a good sealing treatment surface was formed.

[Examples 2 and 3, Comparative Example 1]
In Example 1, when the sealing treatment was similarly performed except that the sulfuric acid concentration, persulfuric acid concentration, oxidation-reduction potential (ORP) and pH shown in Table 1 were used as the sealing treatment liquid, a comparative example was obtained. In No. 1, the anodic oxide film was dissolved during the sealing treatment, but in Examples 2 and 3, good sealing treatment could be performed.

[Experimental Example 1]
Experiment for confirming that the sealing treatment according to the present invention is not a re-dissolution of Al ₂ O ₃ of the anodized film but a competitive reaction between Al ₂ O ₃ dissolution and Al oxidation (Al ₂ O ₃ formation). Went.
Except for using a 20 μm-thick aluminum thin film (purity 99.85%), anodization was performed for 30 minutes in the same manner as in Example 1, and a porous alumina film having through pores was obtained by anodization. It was. Thereafter, the sealing treatment was performed under the same conditions as in Example 1, and the obtained sealing treatment film was washed with pure water and then dried, and the cross section was observed with an electron microscope. The electron micrograph is shown in FIG.
4 that according to the present invention, only the pores in the surface layer are sealed.

DESCRIPTION OF SYMBOLS 1 Treatment tank 2 Constant temperature heater 3 Aluminum substrate 4 Holder 5 Cathode 9 Electrolysis cell for persulfuric acid production

Claims (10)

  A sealing method for aluminum or aluminum alloy, wherein the surface of pores is sealed in a sealing solution for aluminum or aluminum alloy having pores formed on the surface by anodizing, A sealing treatment method for aluminum or an aluminum alloy, wherein the treatment liquid contains sulfuric acid and persulfuric acid, and the oxidation-reduction potential of the sealing treatment liquid is +1.5 to +3.5 V.   In Claim 1, the oxidation-reduction potential of the sealing treatment liquid is set to +1.5 to +3.5 V by any one or more of electrolytic treatment, addition of an oxidizing agent, and addition of a liquid having a high oxidation-reduction potential. A sealing method for aluminum or an aluminum alloy, characterized by adjusting.   3. The sealing treatment according to claim 1, wherein the sealing treatment is performed by any one or more of a circulation treatment of the sealing treatment liquid, a transient addition of the sealing treatment liquid, and a gas blowing into the sealing treatment liquid. A surface treatment method for aluminum or an aluminum alloy, wherein the oxidation-reduction potential of the liquid is adjusted to +1.5 to +3.5 V.   In any 1 item | term of the Claims 1 thru | or 3, the temperature of the said sealing process liquid is 60-90 degreeC, acid concentration is 350-1,600 g / L, oxidizing agent concentration is 2-15 g / L, A method for surface treatment of aluminum or aluminum alloy, wherein the sealing treatment is performed below.   The aluminum or aluminum alloy according to any one of claims 1 to 4, wherein the sealing treatment solution has a sulfuric acid concentration of 350 to 1,600 g / L and a persulfuric acid concentration of 2 to 15 g / L. Sealing treatment method.   The aluminum according to any one of claims 1 to 5, wherein the sealing solution containing sulfuric acid is circulated and circulated through a persulfuric acid producing electrolytic cell to perform electrolytic treatment. Method for sealing aluminum alloy.   6. The aluminum or aluminum alloy sealing treatment method according to claim 1, wherein the sealing treatment liquid is a mixture of sulfuric acid and hydrogen peroxide to produce persulfuric acid. .   6. The aluminum or aluminum alloy sealing treatment method according to claim 1, wherein the sealing treatment liquid generates persulfuric acid by mixing sulfuric acid and ozone.   9. The sealing method for aluminum or aluminum alloy according to claim 1, wherein the aluminum or aluminum alloy is an aluminum base or aluminum alloy base having a thickness of 1 mm or more.   A sealing treatment tank for storing a sulfuric acid-containing treatment liquid, and a persulfuric acid generation electrolytic cell in which the sulfuric acid-containing treatment liquid in the sealing treatment tank is circulated, An aluminum or aluminum alloy characterized in that the oxidation-reduction potential of the liquid in the sealing treatment tank is adjusted to +1.5 to +3.5 V by electrolytically treating the sulfuric acid-containing treatment liquid to generate persulfuric acid. Sealing device.

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