JPH08100290A - Treatment of adhesive substrate of anodic oxide film forming aluminum - Google Patents

Abstract

PURPOSE: To obtain an aluminum material having an anodic oxide film provided with durable adhesion and corrosion resistance and to provide a material formed by adhesion useful as a building structural material. CONSTITUTION: The face of an anodic oxide film formed on an aluminum is electrolyzed in an electrolyte contg. metallic salts and inorg. acid and kept at pH0.1-5.5 at 20-30 deg.C with the electrolyzing voltage controlled to 10-30V AC or a negative voltage. The lightness (L*) of the electrolyzed face is controlled to >=25 or preferably to 30-55 by adjusting electrolysis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating an adhesive anodic oxide film-forming aluminum surface, and more particularly to aluminum having an anodic oxide film formed on its surface for use as a building material (including aluminum alloys. The same applies hereinafter. The post-treatment of the anodic oxide coating of 1) improves the adhesion durability of the anodic oxide coating.

[0002]

2. Description of the Related Art Aluminum for building materials generally has an anodized film (alumite film) on its surface to impart corrosion resistance.
However, when an aluminum material for building materials on which an anodized film is formed, for example, an anodized honeycomb panel face plate and a frame material are bonded with an adhesive or sealing agent (hereinafter, both are referred to as an adhesive), a film is formed. After that, even if an adhesive is applied to the anodized film after a certain period of time to perform the adhesion, the adhesion durability that can maintain the adhesion for a long time becomes insufficient.

In order to provide adhesion durability, it is necessary to apply an adhesive while the anodic oxide film is active and the openings (pores) of the film are not closed to perform the adhesion work. Immediately after forming the oxide film, it is preferable to apply an adhesive agent for adhesion. The reason for this is that the surface of the anodic oxide film is inactivated by the adhesion of moisture and contaminants in the air, and the pores are closed to naturally seal the pores, which reduces the adhesion wettability to the adhesive. .

However, when an adhesive is applied to the surface of the anodic oxide film for adhesion, the holding time from the formation of the anodic oxide film to the application of the adhesive, which is permissible in order to obtain the adhesive effect without deteriorating the adhesion durability ( (Also referred to as pot life) varies depending on the humidity and temperature of the storage environment of the anodized film-formed aluminum, so managing the aluminum material with the anodized film adhered within the pot life is
It is extremely difficult in practice.

When an adhesive member made of an aluminum material is applied as a building structural material, the member is exposed to various corrosive environments under some load.
It is essential to form a completely sealed anodized film to ensure corrosion resistance, but it is difficult to form a durable bonded structure because the sealed anodized film has poor adhesion. Therefore, conventionally, an anodized film-forming aluminum material that satisfies both corrosion resistance and adhesion durability has not been obtained.

Regarding the relationship between the type of anodized film and the adhesion durability, phosphoric acid anodization is the most excellent in terms of adhesion durability, and chromic acid anodization and sulfuric acid anodization decrease in the following order. However, it is said that different results are often obtained depending on the aluminum alloy used as the base and the method of evaluating the adhesion durability.

[0007] The inventors of the present invention are said to be most commonly used for aluminum materials for building materials in order to obtain an anodized film-forming aluminum material that satisfies both corrosion resistance and adhesion durability, and that it has the lowest adhesion durability. As a result of a detailed examination of the relationship between the properties of the film formed by sulfuric acid anodization and the adhesion durability, the presence of sulfate radicals in the film, especially the presence of sulfate radicals in the surface layer of the film in contact with the adhesive, It was found that it was involved in deterioration.

Further, based on the above findings, the inventors first remove the sulfate radicals in the surface layer of the sulfuric acid anodized film to improve the adhesion durability, and then perform a complete sealing treatment to secure the corrosion resistance. Even after that, various studies were conducted on the post-treatment of the anodizing treatment that maintains the improved adhesion durability. As a result, not only the sulfate radicals in the film formed by sulfuric acid anodization are removed, but also the anion radicals are removed from the anodized film formed by a method other than sulfuric acid anodization, which effectively improves the adhesion durability. The present invention has been made by studying specific post-treatment conditions by secondary electrolysis that act and can maintain the adhesion durability even after sealing treatment.

[0009]

SUMMARY OF THE INVENTION The present invention has been made based on the above-mentioned investigation, and its purpose is to bond an anodized film for obtaining an anodized film-forming aluminum material excellent in adhesion durability and corrosion resistance. An object is to provide a ground treatment method.

[0010]

In order to achieve the above object, the method of pretreatment of anodized film-formed aluminum according to the present invention comprises: The treatment temperature is set to 20 in an electrolytic solution containing an inorganic acid and having a pH adjusted to 0.1 to 5.5.
It is characterized in that AC electrolysis is performed at -30 ° C and an electrolysis voltage of 10-30V.

Further, the surface of the anodized film of aluminum having an anodized film formed thereon is used as a cathode in an electrolytic solution containing a metal salt and an inorganic acid and having a pH adjusted to 0.1 to 5.5. , Processing temperature 20 ~ 30 ℃, electrolytic voltage
The second feature is that the electrolytic treatment is performed with a negative voltage of 10 to 30V.

Further, the anodic oxide film is formed by using an electrolytic solution containing sulfuric acid as a main component, and the anodic oxide film surface is electrolyzed so that the lightness (L ^* ) of the anodic oxide film surface is 25 or more. The third, fourth, and fifth features of the invention structure are that treatment is performed, and electrolytic treatment is performed, followed by sealing treatment.

In the method of the present invention, the formation of the anodized film on aluminum is carried out by a known method such as sulfuric acid anodizing, phosphoric acid anodizing, chromic acid anodizing, and oxalic acid anodizing. In the present invention, of these anodizing methods, sulfuric acid anodizing performed using an electrolytic solution containing sulfuric acid as a main component is most preferable, and the sulfate radicals in the film are sufficiently removed in the base treatment to ensure the adhesion durability. can get.

In the present invention, the surface of the anodized film formed on the aluminum surface is subjected to electrolytic treatment, preferably immediately after the formation of the anodized film, in an electrolytic solution containing a metal salt and an inorganic acid. The metal salt suppresses the preferential generation of hydrogen due to the presence of metal ions and prevents the destruction (spalling) of the film. Copper sulfate, nickel sulfate, cobalt sulfate, tin sulfate,
Silver sulfate or the like is used. The inorganic acid is added to prevent the metal hydroxide from adhering to the surface and to adjust the pH of the electrolytic solution, and boric acid, sulfuric acid, cresol sulfonic acid and the like are preferably used.

The pH of the electrolytic solution in the secondary electrolytic treatment is 0.1
~ 5.5, the processing temperature is preferably 20 ~ 30 ℃, p of this range
By performing electrolysis using H and temperature, it is possible to prevent dissolution of the anodized film, deposit an appropriate amount of metal, and let out anion roots in the film to improve adhesion durability. . The applied voltage is an alternating current of 10 to 30 V, or a negative voltage of 10 to 30 V is applied with the anodic oxide film surface as a cathode. When an AC negative voltage part or a negative DC voltage acts on the anodized film surface, anion roots such as sulfate radicals flow out of the anodized film into the electrolyte and the anion roots on the surface layer of the film are removed. The durability is improved.

In the present invention, it is preferable that the surface of the anodized film is electrolytically treated so that the lightness (L ^* ) of the surface of the anodized film is 25 or more. More preferably 30 to 55
Electrolyte until the brightness of The lightness (L ^* ) is
It is a display standard of brightness specified in JIS Z 8729, and the brightness decreases as the amount of metal deposited in the secondary electrolytic treatment increases.

When the amount of deposited metal is small and the removal of anion roots is insufficient, the adhesion durability is low and the deposited amount of the deposited metal increases and the adhesive durability improves, but the deposited metal amount becomes too large. When the pores of the film start to overflow, the anion roots are sufficiently removed from the anodized film, but the adhesion durability is reduced. In the present invention, in order to confirm whether or not a predetermined amount of metal is deposited, the lightness (L ^* ) is measured during the secondary electrolysis treatment, and the electrolysis treatment is performed until the lightness within a predetermined range is obtained.

After the electrolytic treatment, a sealing treatment is carried out in order to ensure corrosion resistance. The sealing treatment is preferably carried out by boiling water or hot water washing, and even if this sealing treatment is carried out, the adhesion durability improved by the secondary electrolysis can be maintained.

[0019]

In the present invention, the surface of the anodic oxide film of the aluminum material having the anodic oxide film formed is subjected to secondary electrolysis treatment under specific conditions in an electrolytic solution containing a metal salt and an inorganic acid to form an anodic oxide film. The anion roots of No. 2 flow out into the electrolytic solution, and at least the anion roots such as sulfate roots existing in the surface layer of the film are removed, and the adhesion durability is improved. Even if the secondary electrolytically treated surface is sealed, the improved adhesion durability is maintained, so an anodized film-forming aluminum material having excellent adhesion durability and corrosion resistance can be obtained, and as an adhesive structure material,
It can be used in various environments with a load applied.

[0020]

Hereinafter, examples of the present invention will be described in comparison with comparative examples. Example 1 A commercially available aluminum alloy (A3004) plate material was subjected to sulfuric acid anodization under normal conditions to form an anodized film having a thickness of 12 μm on the surface, and the film surface immediately after the anodization is shown in Table 1. Was subjected to secondary electrolytic treatment and sealing treatment.

[0021]

[Table 1] << Table Note >> 1. Ni sulfate: nickel sulfate Cu sulfate: copper sulfate Sn sulfate: tin sulfate 2. The applied DC voltage was negative.

The lightness (L) of the test material after the secondary electrolysis and sealing treatment
^* ) And the results of the adhesion durability test performed on the test materials are shown in Table 2. As shown in Table 2, all the test materials No. 1 to No. 8 produced according to the present invention have excellent adhesion durability in which the number of days until breakage exceeds 300 days.
The adhesion durability test was conducted by the following method.

Adhesion durability test: From the test material, width 25 mm, length
Cut out 100mm specimens, two specimen ends, width 25mm ×
The 12.5 mm long part was mixed with the main component of the two-component epoxy adhesive Alon Mighty XTS-04SG (manufactured by Toagosei Co., Ltd.) and the curing agent at a weight ratio of 1: 1 and applied at a thickness of 150 μm. Combined, heat-cure at 50 ℃ for 5 hours to make a simple lap joint in accordance with JIS K 6850. With a load of 10 kgf / cm ² , the temperature is 80 ℃ and the relative humidity is 95%. It is installed in a tank and the number of days until breakage is measured to evaluate the adhesion durability.

[0024]

[Table 2]

Comparative Example 1 Similar to Example 1, a commercially available aluminum alloy (A3004) plate material was subjected to sulfuric acid anodization under ordinary conditions to obtain a surface of 12 μm.
The anodic oxide film was formed, and the surface of the film immediately after the anodic oxidation treatment was subjected to secondary electrolytic treatment and sealing treatment under the conditions shown in Table 3. N
For the test materials of o.8 to No.10, only the sealing treatment was performed without electrolytic treatment. The adhesion durability of these test materials was evaluated by the same method as in Example 1. Table 4 shows the number of days until breakage and the brightness (L ^* ) of the test material in the adhesion durability test. In Tables 3 and 4, those outside the conditions of the present invention are underlined.

[0026] <Table Note> 1. Ni sulfate: Nickel sulfate Sn: Sn sulfate 2. Negative voltage is applied for test materials No. 1 to 2, positive (plus) voltage is applied for test material No. 6.

[0027]

[Table 4]

As shown in Table 4, test materials No. 1 and No 2
, No. 3, the brightness was less than 25, and the adhesion amount was inferior because the amount of metal deposited in the electrolytic treatment was too large. Since the test material No. 4 completed the electrolysis with the brightness of 65, the sulfate radicals were not sufficiently removed from the anodized film during the electrolytic treatment, and the adhesion durability was poor. Test material No. 5 has a low voltage during electrolytic treatment, test material No. 6 applies a positive DC voltage, and test material N
In the case of o.7, the temperature of the electrolytic treatment is low, so in all cases, the sulfate radicals were not sufficiently removed from the film, and the adhesion durability was reduced. Since the test materials Nos. 8 to 10 were not subjected to the electrolytic treatment of the present invention, the sulfuric acid radicals were not removed from the anodized film, and all were broken in the adhesion durability test in a short period of time.

[0029]

As described above, according to the present invention, an aluminum material having an anodic oxide coating having adhesion durability and corrosion resistance can be obtained and is useful as a building structural material such as a honeycomb panel for bonding. In the anodized film-forming aluminum material according to the method of the present invention, it is not necessary to apply the adhesive immediately after the anodizing treatment and the electrolytic treatment for forming the bonding underlayer, and the so-called good adhesiveness between the electrolytic treatment and the bonding step. Since there is enough time to use, it is not necessary to make the anodizing process and the bonding process continuous lines.

Claims (5)

[Claims] 1. The treatment temperature of an anodized film surface of aluminum having an anodized film formed on the surface thereof in an electrolytic solution containing a metal salt and an inorganic acid and having a pH adjusted to 0.1 to 5.5.
A method for treating an adhesive anodic oxide film-formed aluminum substrate, which comprises performing an alternating current electrolytic treatment at 20 to 30 ° C. and an electrolytic voltage of 10 to 30V. 2. An anodized film surface of aluminum having an anodized film formed on the surface thereof is used as a cathode in an electrolytic solution containing a metal salt and an inorganic acid and having a pH adjusted to 0.1 to 5.5. , Processing temperature 20 ~ 30 ℃, electrolysis voltage 10
An anodizing film-forming aluminum adhesion substrate treatment method, characterized in that electrolytic treatment is performed with a negative voltage of -30 V. 3. The method for treating the adhesive underlayer of anodized film-formed aluminum according to claim 1, wherein the anodized film is formed by using an electrolytic solution containing sulfuric acid as a main component. 4. The adhesion base of anodized film-formed aluminum according to claim 1, wherein the anodized film surface is electrolytically treated so that the lightness (L ^* ) of the anodized film surface is 25 or more. Processing method. 5. The method for treating an adhesive anodic oxide film-formed aluminum substrate according to claim 1, wherein a sealing treatment is performed after the electrolytic treatment.