TWI647340B - Surface-treated aluminum material and manufacturing method thereof, and joint body of surface-treated aluminum material / resin layer - Google Patents

Abstract

Provided is a surface-treated aluminum material covering the entire surface of the aluminum material, which is excellent in long-term resin adhesion, and a stable manufacturing method of the surface-treated aluminum material.

A surface-treated aluminum material and a manufacturing method thereof. The surface-treated aluminum material is characterized in that it contains an aluminum material and an oxide film formed on at least one of the surfaces thereof; the oxide film is formed by a porous material having a thickness of 20 to 500 nm formed on the surface side. The aluminum oxide film layer is composed of a barrier-type aluminum oxide film layer formed on the substrate side and having a thickness of 3 to 30 nm; small holes having a diameter of 5 to 30 nm are formed in the porous aluminum oxide film layer; and the water content in the foregoing oxide film It is below 10 μg / cm ² .

Description

Surface-treated aluminum material, manufacturing method thereof, and joint body of surface-treated aluminum material / resin layer Field of invention

The present invention relates to a surface-treated aluminum material, a method for manufacturing the same, and the surface-treated aluminum material / resin layer joint. Specifically, the invention relates to covering the entire surface of the aluminum material with long-term adhesion and adhesion. An excellent surface-treated aluminum material, a method for producing such a surface-treated aluminum material, and a bonded body of the surface-treated aluminum material / resin layer having excellent adhesion and adhesion.

Background of the invention

Pure aluminum or aluminum alloy (hereinafter referred to as "aluminum") has light weight and moderate mechanical characteristics, and has excellent characteristics such as aesthetics, formability, and corrosion resistance. Therefore, it is widely used in various containers and structural materials. And mechanical parts. These aluminum materials can be used directly, on the other hand, they can be added and improved by applying various surface treatments to improve corrosion resistance, abrasion resistance, resin adhesion, hydrophilicity, water repellency, antibacterial, creative, infrared Radioactive, highly reflective and other functions.

For example, an anodizing treatment (so-called anodized aluminum) is often widely used as a surface treatment method for improving corrosion resistance and abrasion resistance. Specifically, as described in Non-Patent Documents 1 and 2, an aluminum material is immersed in an acid. In the electrolytic solution, direct current is used for electrolytic treatment to form an anodic oxide film with a thickness of several to several tens of μm on the surface of the aluminum material, and various treatment methods have been proposed according to the application.

In addition, in terms of a surface treatment method for improving the adhesion of the resin, there is an alkali alternating electrolytic method as proposed in Patent Document 1. That is, it forms an oxide film, which is composed of a porous aluminum oxide film layer with a thickness of 20 to 500 nm on the surface of the aluminum material and a barrier-type aluminum oxide film layer with a thickness of 3 to 30 nm formed on the substrate side. The porous aluminum oxide film layer has small pores with a diameter of 5 to 30 nm. The total thickness of the foregoing porous aluminum oxide film layer and the barrier-type aluminum oxide film layer on the entire surface of the aluminum material varies within the arithmetic mean of the total thickness. Within ± 50% of the value. Specifically, an aluminum electrode and a counter electrode are used. An alkaline aqueous solution having a pH of 9 to 13, a liquid temperature of 35 to 80 ° C, and a dissolved aluminum concentration of 5 ppm to 1,000 ppm is used as the electrolytic solution, and the frequency is 20 to 100 Hz and the current density. The above-mentioned oxide film is obtained by performing AC electrolytic treatment under conditions of 4 to 50 A / dm ² and an electrolysis time of 5 to 60 seconds.

However, even if the technology of Patent Document 1 is used and the treatment is performed under the same electrolytic conditions, the resin adhesiveness may be reduced after a long period of time. Specifically, for example, peeling and the like caused by a decrease in adhesiveness of a resin are seen in a joint member that has been under normal temperature and pressure for 5 to 10 years.

Prior art literature Non-patent literature

Non-Patent Document 1: Aluminium Handbook 7th Edition, 179-190 pages, 2007, Japan Aluminum Alloy Association Japan Aluminium Association

Non-Patent Document 2: Japanese Industrial Standard JIS H8601, "Anodic Oxide Coatings on Aluminum and Aluminum Alloys" (1999)

Patent literature

Patent Document 1: International Publication No. WO2013 / 118870

Summary of invention

The object of the present invention is to provide a surface-treated aluminum material which is excellent in long-term adhesion and adhesion over the entire surface of the aluminum material, a method for manufacturing such a surface-treated aluminum material, and a surface treatment which is excellent in adhesion and adhesion. Aluminum / resin layer joint.

In order to solve the above-mentioned problem, the inventors of the present invention have found out from the results of repeated improvement studies of Patent Document 1 that the adhesion and the adhesiveness decrease after a long period of time are received by a very small amount of moisture existing in the porous aluminum oxide film layer. influences. Furthermore, it has been found that, for the purpose of improving performance, after forming the oxide film by alternating current electrolytic treatment in an alkaline solution, exposing the aluminum material formed with the oxide film to a gas environment exceeding 150 ° C can effectively remove the moisture.

That is, in the present invention, item 1 is a surface-treated aluminum material, which is characterized in that it contains an aluminum material and an oxide film formed on at least one of the surfaces thereof; the oxide film is formed on the surface side and has a thickness of 20 to 500 nm The porous aluminum oxide film layer is composed of a barrier-type aluminum oxide film layer formed on the substrate side and having a thickness of 3 to 30 nm; small holes having a diameter of 5 to 30 nm are formed in the porous aluminum oxide film layer; The water content is 10 μg / cm ² or less.

Furthermore, in the second aspect of the present invention, as described in the first aspect, a variation range of a total thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer is within ± 50% of an arithmetic mean value of the total thickness.

The item 3 in the present invention is a method for manufacturing a surface-treated aluminum material, and is a method for manufacturing the surface-treated aluminum material as described in item 1, which is characterized in that a surface-treated aluminum material electrode and a counter electrode are used. 13 An alkaline aqueous solution with a liquid temperature of 35 to 85 ° C is used as an electrolytic solution. AC electrolytic treatment is performed under the conditions of a frequency of 10 to 100 Hz, a current density of 4 to 50 A / dm ² and an electrolysis time of 5 to 300 seconds. An oxide film is formed on the surface of the foregoing aluminum material facing the opposite electrode, and the aluminum material on which the oxide film has been formed is exposed to a gas environment exceeding 150 ° C.

In the fourth aspect of the present invention, as described in the third aspect, the electrolytic solution of the alkaline aqueous solution contains 5 ppm or more and 1,000 ppm or less of dissolved aluminum.

In the present invention, item 5 is set as item 3 or 4, wherein when the thickness of the porous aluminum oxide film layer is L (nm) and the gas environment temperature is T (° C), the aforementioned Time t (seconds) satisfies the relationship of t ≧ 20 × L / T. In the present invention, the item 6 is set to any one of items 3 to 5, wherein the temperature of the surface of the aluminum material on which the oxide film has been formed reaches 150 ° C since the end of the AC electrolytic treatment is exposed to a gas environment exceeding 150 ° C. The time is within 24 hours. In addition, in the seventh aspect, the present invention is set to any one of the third to sixth aspects, wherein the relative humidity of the gaseous environment is 50% or less.

The present invention is set as a surface-treated aluminum material / resin layer in item 8 The bonded body is characterized in that a resin layer is bonded to the surface-treated surface of the surface-treated aluminum material according to item 1 or 2.

The item 9 of the present invention is as described in item 8, wherein the resin used in the resin layer has at least one polar functional group selected from the group consisting of an amine group, a sulfonylamine group, an ester group, a carboxyl group, an epoxy group, and a hydroxyl group.

In the present invention, item 10 is set as item 9, wherein in the infrared absorption spectrum of the aforementioned resin, when the absorptivity at the wave number νcm ^-1 is represented by I ( v ), the value of the following formula 1 is 0.01 or more and 3.0 or less .

According to the present invention, it is possible to uniformly form a long-term stable oxide film having high adhesion and high adhesion to resins and the like on the entire surface of the aluminum material. Therefore, a surface-treated aluminum material having excellent adhesion and adhesion, and adhesion and This surface-treated aluminum material / resin layer joint is excellent in adhesion.

Specifically, the oxide film on the surface of the aluminum material is a two-layer structure of a porous aluminum oxide film layer and a barrier-type aluminum oxide film layer. In addition, the porous aluminum oxide film layer formed on the surface side of the aluminum material, having a thickness of 20 to 500 nm and having pores with a diameter of 5 to 30 nm, can suppress its own cohesive failure and increase its surface area at the same time. In order to improve the adhesion and adhesion of the joint with resin and the like. In addition, by forming a barrier-type aluminum oxide film layer having a thickness of 3 to 30 nm on the substrate side of the aluminum material, the aluminum substrate and the porous aluminum oxide film layer can be combined to improve adhesion and adhesion. Furthermore, by limiting the moisture content in the oxide film to 10 μg / cm ² or less, the area where the joints such as resin and the porous aluminum oxide film layer contact can be increased, and at the same time, the porous aluminum can be reduced after a long period of time. The amount of water vapor generated inside the oxide film can maintain a relatively high adhesion and adhesion for a long period of time.

In addition, by changing the total thickness of the total thickness of the oxide film on the surface of the aluminum material to within ± 50% of the arithmetic mean of the total thickness, the entire surface of the aluminum material can exhibit excellent adhesion and adhesion. Sex.

The surface-treated aluminum material obtained by the above-mentioned method is coated with a joint such as a resin on the treated surface due to its excellent adhesiveness, and is therefore suitable for various applications. Here, when a resin is used as a joint, any of a thermosetting resin and a thermoplastic resin can be applied, and various effects can be imparted in combination with the oxide film formed on a specific treatment surface of the present invention. Generally, the thermal expansion rate of the resin is larger than that of the aluminum material, so the joint of the aluminum material and the resin is prone to peel or cut off the interface. However, in the bonded body of the surface-treated aluminum material and the resin of the present invention, since the adhesiveness is high, the stress generated at the bonding interface due to the poor thermal expansion coefficient is accumulated by the internal stress of the surface-treated aluminum material and / or the resin. . As a result, peeling or cutting at the interface can be suppressed. The joint of the surface-treated aluminum material and the thermoplastic resin of the present invention is suitable for use as a lightweight and highly rigid composite material. The bonded body of the surface-treated aluminum material and the thermosetting resin of the present invention is suitable for use in printed wiring boards and the like.

In addition, in the method for manufacturing a surface-treated aluminum material of the present invention, by appropriately setting AC electrolytic treatment conditions, When the heat treatment is performed under the conditions, the above-mentioned surface-treated aluminum material can be stably produced.

FIG. 1 is a graph for schematically illustrating an infrared absorption spectrum showing an integrated value region of a denominator of Formula 1. FIG.

Forms used to implement the invention

Hereinafter, the present invention will be described in detail in order. The surface-treated aluminum material of the present invention has an oxide film formed on its surface, and the oxide film is composed of a porous aluminum oxide film layer formed on the surface side and a barrier-type aluminum oxide film layer formed on the substrate side. In addition, small holes are formed in the porous aluminum oxide film layer.

A. Aluminum

As the aluminum material used in the present invention, pure aluminum or aluminum alloy can be used. The aluminum alloy composition is not particularly limited, and various alloys including alloys specified by JIS can be used. There is no particular limitation on the shape, but from the viewpoint of being capable of stably forming a treatment film, a flat plate-like thing is preferably used. The thickness can be appropriately selected according to the application, but from the viewpoint of weight reduction and formability, 0.05 to 2.0 mm is preferable, and 0.1 to 1.0 mm is more preferable.

B. Oxide film

The aluminum material used in the present invention has a porous aluminum oxide film layer formed on the surface side and a barrier-type aluminum oxide film layer formed on the substrate side on the surface. That is, an oxide film is provided on the surface of the aluminum material, and the oxide film is composed of two layers of a porous aluminum oxide film layer and a barrier-type aluminum oxide film layer. The porous aluminum oxide film layer can exhibit strong adhesion and adhesion for a long time. In terms of the barrier-type aluminum oxide film layer, the entire aluminum oxide film layer can be firmly combined with the aluminum matrix.

B-1. Porous aluminum oxide film layer

The thickness of the porous aluminum oxide film layer is 20 to 500 nm. When the thickness is less than 20 nm, the thickness is insufficient, and the formation of the pore structure described later is likely to be insufficient, and the adhesion and adhesion are reduced. On the other hand, if it exceeds 500 nm, the porous aluminum oxide film layer itself becomes easily cohesive and broken, thereby reducing the adhesion. The thickness of the porous aluminum oxide film layer is preferably 50 to 400 nm.

The porous aluminum oxide film layer has pores extending from the surface toward the depth direction. The pinhole diameter is 5 ~ 30nm, ideally 10 ~ 20nm. This pinhole system has the effect of increasing the contact area between the resin layer or the adhesive and the aluminum oxide film, and further increasing the adhesion and adhesion. If the pore diameter is less than 5 nm, the contact area will be insufficient and sufficient adhesion and adhesion cannot be obtained. On the other hand, if the diameter of the pores exceeds 30 nm, the entire porous aluminum oxide film layer becomes fragile and cohesive failure occurs, resulting in a decrease in adhesion and adhesion.

The ratio of the total pore area of the small pores to the surface area of the porous aluminum oxide film layer is not particularly limited. The ratio of the total pore area of the small pores to the apparent surface area of the porous aluminum oxide film layer (the area expressed by the product of length and width irrespective of the small unevenness on the surface, etc.) is preferably 25 to 75%. If it is less than 25%, the contact area may be insufficient and sufficient adhesion and adhesion may not be obtained. On the other hand, if it exceeds 75%, the entire porous aluminum oxide film layer may become fragile and cohesive failure may occur, resulting in a decrease in adhesion and adhesion.

B-2. Barrier type aluminum oxide film layer

The thickness of the barrier-type aluminum oxide film layer is 3 to 30 nm. If it is less than 3nm, the interposer cannot provide sufficient bonding force for the bonding between the porous aluminum oxide film layer and the aluminum matrix, and the bonding force becomes insufficient in particular in severe environments such as high temperature and humidity. On the other hand, if it exceeds 30 nm, the barrier-type aluminum oxide film layer will be easily cohesive and broken due to its compactness, but the adhesion and adhesion will be reduced instead. The thickness of the barrier-type aluminum oxide film layer is preferably 5 to 25 nm.

B-3. Moisture content in oxide film

The amount of water that can be contained in the oxide film must be 10 μg / cm ² or less. Specifically, the moisture detected from 1 cm ² of the apparent surface area (vertical × horizontal) of the surface-treated aluminum material must be 10 μg / cm ² or less. If the structure of the oxide film is considered, it can be assumed that most of the water content is adsorbed inside the porous aluminum oxide film layer. If the moisture content in the oxide film exceeds 10 μg / cm ² , especially in the case of a long period of time, water vapor equivalent to its moisture content will be generated, and the oxide film will expand in volume due to the water vapor. In addition, due to the volume expansion, peeling stress of the oxide film and the joint such as the resin is generated, and at the same time, hydrogen bonds originally generated at the joint interface between the oxide film and the joint are dissociated. As a result, the adhesive force and adhesion force after a long period of time are reduced. Furthermore, under the relevant water content limit is not particularly specified, but in accordance with the measurement method described later, 0.1μg / cm ² before and after the detection limit, the lower limit value can thus be said that the industry also about 0.1μg / cm ^2. The moisture content in the oxide film is preferably 6 μg / cm ² or less.

B-4. Variation of overall thickness of oxide film

The thickness of the entire oxide film, that is, the thickness of the porous aluminum oxide film layer described in B-1 and the thickness of the barrier aluminum oxide film layer described in B-2, regardless of the location on the aluminum material. It must be within ± 50%, and preferably within ± 20%. That is, when the average value of the entire thickness of the oxide film measured at any number of places on the surface of the aluminum material (more than 10 points is preferred, and more than 10 points are preferred) is T (nm) It is preferable that the overall thickness of all the oxide films located at the positions where the majority of the measurements are made is in the range of (0.5 × T) to (1.5 × T). For example, the following method is to prepare ten sample pieces prepared under the same conditions, measure the overall thickness of the oxide film at 10 points for each of these samples, and obtain a total of 100 measured values for the samples prepared under the same conditions. The following methods can also be cited instead: For example, the vertical and horizontal directions of a rectangular test piece are respectively divided into 5 and 4 lines, and the overall thickness of the oxide film near its intersection (12) By measuring 10 points, a total of 120 measured values were obtained for the same sample.

If there is a place smaller than (0.5 × T), the oxide film there will become thinner than the surrounding area. As a result, in the thin place of the film, a gap is easily generated between the adhesive or the resin layer to be bonded and the oxide film, and a sufficient contact area cannot be secured, which may reduce the adhesive force and adhesion. On the other hand, once there is a place exceeding (1.5 × T), the oxide film there becomes thicker than the surrounding area. As a result, stress from the resin layer or the like to be bonded may be concentrated at the place where the film thickness is located, and the adhesion and adhesion may be relatively reduced.

Furthermore, where the overall thickness of the oxide film is a thin film or a thick film, the optical characteristics are different from those of the surroundings, so it is possible Changes in hue such as dark brown or white turbidity are visually recognized.

C. Surface treatment aluminum manufacturing method

One of the methods for producing a surface-treated aluminum material having an oxide film on the surface that satisfies the above conditions includes the following methods: using an electrode and a counter electrode of a surface-treated aluminum material, at a pH of 9 to 13, and a liquid temperature of 35 to 85 An alkaline aqueous solution at ℃ is used as an electrolytic solution, and an alternating current electrolytic treatment is performed under the conditions of a frequency of 10 to 100 Hz, a current density of 4 to 50 A / dm ² and an electrolysis time of 5 to 300 seconds. After an oxide film is formed on the surface, it is exposed to a gas environment exceeding 150 ° C.

In the step of alternating current electrolytic treatment, the alkaline aqueous solution used as the electrolytic solution may use phosphates such as sodium phosphate, potassium hydrogen phosphate, sodium pyrophosphate, potassium pyrophosphate, and sodium metaphosphate; and alkali metal hydrogen such as sodium hydroxide and potassium hydroxide Oxides; carbonates such as sodium carbonate, sodium bicarbonate, potassium carbonate; ammonium hydroxide; or aqueous solutions of these mixtures. Since it is necessary to maintain the pH of the electrolytic solution within a specific range as described later, it is preferable to use an alkaline aqueous solution containing a phosphate-based substance with a desired buffering effect. The concentration of the alkali component contained in the alkaline aqueous solution can be adjusted so that the pH of the electrolytic solution becomes a desired value, usually 1 × 10 ^-4 to 1 mol / liter, and ideally 1 × 10 ^-3 to 0.8 mol / liter . In addition, in these alkaline aqueous solutions, a surfactant can be added to improve the ability to remove dirt components.

The pH of the electrolytic solution must be set to 9 ~ 13, and preferably 9.5 ~ 12. When the pH is lower than 9, the alkali etching force of the electrolytic solution is insufficient, and the porous structure of the porous aluminum oxide film layer becomes incomplete. On the other hand, if the pH exceeds 13, the alkali etching force becomes excessive, making it difficult for the porous aluminum oxide film layer. To grow, it also hinders the formation of barrier-type aluminum oxide film layers.

The temperature of the electrolytic solution should be set to 35 ~ 85 ° C, and preferably 40 ~ 70 ° C. Once the temperature of the electrolytic solution is lower than 35 ° C, the porous structure of the porous aluminum oxide film layer becomes incomplete due to insufficient alkali etching power. On the other hand, if it exceeds 85 ° C, the alkali etching force will be excessive and hinder the growth of both the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer.

In alkaline AC electrolysis, the overall thickness of the oxide film including the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer is controlled by the amount of electricity, that is, the product of the current density and the electrolytic time. Basically, the more the electricity, the more the entire oxide film The thickness increases. From this viewpoint, the AC electrolytic conditions of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer are as follows.

The frequency used for AC electrolysis is 10 ~ 100Hz, and ideally 20 ~ 90Hz. When the frequency is lower than 10 Hz, the direct current factor is increased in the electrolysis. As a result, the formation of the porous structure of the porous aluminum oxide film layer cannot be performed, and a dense structure is formed. On the other hand, if it exceeds 100 Hz, the reverse of the anode and the cathode will be too fast, and the formation of the oxide film as a whole will be extremely slow. As a result, the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer will both become predetermined thicknesses. It takes an extremely long time. Furthermore, the electrolytic waveform of AC electrolysis is not particularly limited, and waveforms such as a sine wave, a rectangular wave, a trapezoidal wave, and a triangular wave can be used.

The current density is set to 4 to 50 A / dm ² and ideally 5 to 45 A / dm ² . When the current density is lower than 4 A / dm ² , only a barrier-type aluminum oxide film layer is preferentially formed, so that a porous aluminum oxide film layer cannot be obtained. On the other hand, if it exceeds 50 A / dm ² , the current becomes too large, and it is difficult to control the thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer, which may cause uneven processing.

The electrolysis time is set to 5 to 300 seconds and ideally 10 to 240 seconds. This is because, under a processing time of less than 5 seconds, the formation of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer is excessively rapid, so that any oxide film layer cannot be fully formed, and it becomes an amorphous aluminum. An oxide film made of oxide. On the other hand, if it exceeds 300 seconds, the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer become too thick, which may cause re-dissolution, and further reduce productivity.

In addition, in the above manufacturing method, for the purpose of reducing the thickness variation of the oxide film, the dissolved aluminum concentration contained in the electrolytic solution is preferably 5 ppm or more and 1000 ppm or less, and more preferably 10 ppm or more and 800 ppm or less. When the dissolved aluminum concentration is less than 5ppm, the initial oxide film formation reaction of the electrolytic reaction will be initiated sharply, and the thickness of the formed oxide film will be easily affected by the drop in the processing steps such as the state of dirt on the aluminum surface or the installation state of the aluminum influences. As a result, a thick-film oxide film is locally formed. On the other hand, when the dissolved aluminum concentration exceeds 1000 ppm, the viscosity of the electrolytic solution will increase, and the uniform convection near the surface of the aluminum material will be hindered during the electrolytic step. At the same time, the dissolved aluminum will play a role in suppressing the formation of the film. As a result, a thin oxide film is locally formed. If the dissolved aluminum concentration exceeds the above range, it will be difficult to make the total thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer on the entire surface of the aluminum material change within ± 50% of the arithmetic mean of the total thickness. It may cause a decrease in adhesion and adhesion of the obtained oxide film.

One of the pair of electrodes used in the AC electrolytic treatment is an aluminum material which should be subjected to electrolytic treatment. As the other counter electrode, for example, well-known electrodes such as black lead, aluminum, and titanium electrodes can be used. However, in the present invention, it is necessary to use an electrode that does not deteriorate the alkaline composition or temperature of the electrolytic solution, has good conductivity, and does not cause electrochemical problems. Material of reaction. From this point of view, a black lead electrode should be used as the counter electrode. This is because the black lead electrode is chemically stable, and it is easy to start at a low price. In addition, by virtue of the majority of pores existing in the black lead electrode, the power line can be moderately diffused in the AC electrolysis step, so it is easy to make it porous The aluminum oxide film layer and the barrier-type aluminum oxide film layer become more uniform together.

In the present invention, it is preferable to use a flat plate shape for the aluminum material and the opposite electrode that should be subjected to electrolytic treatment, and it is desirable to make the opposite sides of the opposite aluminum material and the opposite electrode have substantially the same horizontal and vertical dimensions. Perform electrolytic operation. At this time, an oxide film may be formed on one surface of the aluminum material facing the opposite electrode. Here, if it is also desired to form an oxide film on the other surface of the aluminum material that does not oppose the opposite electrode, the AC electrolytic treatment is temporarily ended after the oxide film is formed on one surface, and then the other surface is reconfigured to be opposite to the opposite electrode. The opposite direction may be subjected to AC electrolytic treatment in the same manner. Further, when the shape of the aluminum material is a pellet bar or a corner material other than a plate, the electrolysis step is repeated by re-arranging the surface that does not face the opposite electrode to face the opposite electrode in the electrolysis step. An oxide film can be formed on a desired surface.

By exposing the aluminum material obtained in the above manner to a gas environment exceeding 150 ° C, the water content in the oxide film can be effectively removed. At 150 ℃ Under the following temperature environment, water vapor cannot be detached from the inside of the porous aluminum oxide film layer, so the moisture contained in the oxide film cannot be removed. In addition, in terms of the gas environment, the atmosphere, inert gas such as nitrogen or argon, a mixed gas of these inert gases, and a mixed gas of the atmosphere and an inert gas can be used, but the atmosphere is preferred from the viewpoint of economy. The relative humidity of the gas environment to be exposed is preferably 50% or less, and more preferably 30% or less. If the relative humidity exceeds 50%, the moisture contained in the oxide film may not be effectively removed.

In addition, regarding the time of exposure to a gas environment exceeding 150 ° C, it is desirable to set the exposure time to t (seconds), the thickness of the porous aluminum oxide film layer to L (nm), and the gas ambient temperature to T (° C). Meet the relationship of t ≧ 20 × (L / T). This is a calculation formula based on the assumption that most of the moisture in the oxide film is adsorbed inside the porous aluminum oxide film layer. The exposure time is proportional to the thickness of the porous aluminum oxide film layer or increases with the ambient temperature of the gas. Reduced inversely. Here, the coefficient 20 is a constant determined experimentally. The upper limit of the ambient temperature of the gas is preferably 500 ° C, and more preferably 300 ° C.

In addition, for exposure to a gaseous environment exceeding 150 ° C, the time from the end of the alternating current electrolytic treatment to a temperature of more than 150 ° C until the surface temperature of the aluminum material on which the oxide film has formed reaches 150 ° C, preferably within 24 hours, Preferably within 12 hours. The moisture absorbed in the oxide film produced by the AC electrolysis step is fixed to the hydroxide with Al ₂ O ₃ ‧ nH ₂ O (n is an integer of 1 to 3) in a very small amount, but it will be accompanied by the passage of time. aluminum. The moisture fixed to aluminum hydroxide in this state is sometimes difficult to remove by successive exposure to a gaseous environment exceeding 150 ° C. The alternating-current electrolytic treatment is carried out through each step of electrolytic treatment-washing-drying, and the starting time point within 24 hours is set to the time point when the voltage application of the electrolytic treatment has been stopped. On the other hand, the end time within 24 hours is set to the state that the surface of the aluminum material subjected to AC electrolysis treatment has been connected with a thermometer such as a thermocouple, and it is exposed to a gas environment exceeding 150 ° C and displayed on the thermometer. The time point is 150 ° C. Generally, from the beginning of exposure to a gas environment exceeding 150 ° C, the thermometer will display 150 ° C in about 60 seconds.

Furthermore, for the structural observation and thickness measurement of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer of the present invention, cross-sectional observation by a transmission electron microscope (TEM) is suitably used. Specifically, the thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer, and the pore diameter of the porous aluminum oxide film layer can be measured by making a thin sample with an ultra-thin microtome and performing TEM observation.

In addition, in order to measure the water content in the oxide film, a surface trace moisture measurement method using a thermal desorption spectrum analyzer (TDS-MS) can be used. Specifically, the surface-treated aluminum material is placed in a closed tank, and heated to a temperature that is 5 to 10 ° C lower than the solidus temperature of the aluminum material at a heating rate of 10 to 60 ° C / min. Then, the gas component generated during heating was analyzed with a mass spectrometer, and the component with a mass number (m / z) of 18 was quantified and measured.

In the present invention, an oxide film can be formed on at least one surface of the aluminum material through an AC electrolytic treatment step, and then the moisture of at least one of the foregoing oxide films can be reduced by exposure to a gas environment exceeding 150 ° C. When using a plate as an aluminum material, only one side can be made into a surface-treated surface, or both sides can be made into a surface-treated surface. Also, even with pill sticks or angles other than plates When aluminum is used as an aluminum material, the desired surface can be similarly subjected to electrolytic treatment and exposed to a gaseous environment exceeding 150 ° C. to form the surface as a surface-treated surface.

E. Surface-treated aluminum / resin layer joint

By bonding the resin layer to the surface-treated surface of the surface-treated aluminum material of the present invention, a surface-treated aluminum material / resin layer bonded body can be obtained. As the resin for the resin layer, various thermoplastic and thermosetting resins can be used. When a thermoplastic resin is used, the resin can be formed by contacting ‧ the resin which has been heated to a flowing state and soaking into the porous aluminum oxide film layer, followed by cooling and solidification. Instead of heating and curing, the adhesive can be contacted and penetrated into the porous aluminum oxide film layer, and the resin layer can be bonded to the surface-treated aluminum material through the adhesive. The adhesive may be a liquid type or a hot-melt type.

The resin used in the resin layer bonded to the surface-treated surface of the surface-treated aluminum material of the present invention preferably has a polar functional group selected from the group consisting of an amine group, a amine group, an ester group, a carboxyl group, an epoxy group, and a hydroxyl group. At least one.

Since the resin has the above-mentioned polar functional group, not only does the anchoring effect occur due to the resin impregnating the porous aluminum oxide film, the polar functional group and the oxide film can also attract each other by Coulomb force and / or hydrogen bonding force, and have Excellent primary adhesion. Furthermore, since the moisture content in the oxide film formed on the surface-treated surface of the surface-treated aluminum material of the present invention is 10 μg / cm ² or less, the moisture cannot hinder the Coulomb force and / or the bonding force of the bonding interface between the oxide film and the resin. Hydrogen bonding, and excellent secondary adhesion.

In the resin used for the resin layer bonded to the surface-treated surface of the surface-treated aluminum material of the present invention, the value shown in Formula 1 is the extreme value in the resin. The presence ratio of the sexual functional group is preferably 0.01 or more and 3.0 or less.

The molecule of Formula 1 is an integrated value of an infrared absorption spectrum derived from an amine group, a amine group, an ester group, a carboxyl group, an epoxy group, and a hydroxyl group, a wave number range in which the spectrum appears, and a region surrounded by the horizontal axis. That is, there is a predetermined amount of polar functional groups present in the resin. In addition, the denominator of Formula 1 is an integrated value of an infrared absorption spectrum derived from an aliphatic hydrocarbon and a benzene ring, a wave number range in which the spectrum appears, and a region surrounded by the horizontal axis. Specifically, it is shown in Figure 1 as the integral value of the following areas: from the line of infrared absorption spectrum derived from aliphatic hydrocarbons and benzene rings, through the two vertical lines and labels showing the wave number range of 2835cm ^-1 and 2975cm ^-1 The area enclosed by the horizontal axis of the wave number; and the line composed of the infrared absorption spectrum derived from the aliphatic hydrocarbon and the benzene ring, passing through two perpendicular lines showing the wave number range of 1575 cm ^-1 and 1625 cm ^-1 , and the horizontal axis indicating the wave number The area enclosed. In addition, the integral value of the numerator of Formula 1 is also the integral value of the area obtained in the same manner. In this way, the amount of the polar functional group existing in the resin is specified. That is, Formula 1 specifies the existence ratio of the skeleton structure of the resin with respect to the polar functional group, and the larger the value, the more polar the resin is.

If the value shown in Formula 1 is 0.01 or more and 3.0 or less, the interfacial bonding force of the interface between the oxide film and the polar functional group of the resin by Coulomb force and / or hydrogen bonding force will increase, and the strength of the resin itself will increase. Increased, thereby improving primary adhesion and secondary adhesion.

As the thermoplastic resin, for example, polyolefin (polyethylene, polypropylene, etc.), polyvinyl chloride, polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), polyamine , Polyphenylene sulfide, aromatic polyetherketone (poly Ether ether ketone, polyether ketone, etc.), polystyrene, various fluororesins (polytetrafluoroethylene, polychlorotrifluoroethylene, etc.), ethylene- (meth) acrylic copolymer, propylene- (meth) acrylic copolymer , Acrylic resin (polymethyl methacrylate, etc.), ABS resin, polycarbonate, thermoplastic polyimide, etc. Preferred are polyester, polyamide, ethylene- (meth) acrylic copolymer, propylene- (meth) acrylic copolymer, and thermoplastic polyimide.

In the case of using a thermosetting resin, the resin having a fluid state before curing may be contacted and impregnated into the porous aluminum oxide film layer, followed by curing. Alternatively, instead of the hardening method, the liquid or hot-melt adhesive can be contacted and penetrated into the porous aluminum oxide film layer in the same manner as the thermoplastic resin, and the resin layer and the resin layer can be penetrated through the adhesive. Surface treatment aluminum bonding. Examples of the thermosetting resin include phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyurethane, and thermosetting polyimide.

The thermoplastic resin or the thermosetting resin may be used alone, or a plurality of thermoplastic resins or a polymer blend of a plurality of thermosetting resins may be used in combination. In addition, by adding various fillers, physical properties such as the strength and thermal expansion coefficient of the resin can be improved. Specifically, various fibers such as glass fibers, carbon fibers, and polyaramide fibers, or well-known fillers such as calcium carbonate, magnesium carbonate, silicon dioxide, talc, glass, and clay can be used.

Examples

Hereinafter, suitable embodiments of the present invention will be specifically described based on examples and comparative examples.

Examples 1 to 33 and Comparative Examples 1 to 12

As the aluminum material, a JIS5052-H34 alloy flat plate having a length of 200 mm × a width of 400 mm × a plate thickness of 1.0 mm was used. This aluminum alloy plate was used as one of the electrodes, and a black lead plate having a flat plate shape of 300 mm in length × 500 mm in width × 2.0 mm in thickness was used as the counter electrode. One surface of the aluminum alloy plate and the opposite electrode face each other, and two electrodes are arranged on the surface of the one surface to form a porous aluminum oxide film layer on the surface side and a barrier type aluminum oxide film layer on the substrate side. An alkaline aqueous solution containing sodium pyrophosphate as a main component was used as the electrolytic solution. The alkali component concentration of the electrolytic solution was set to 0.5 mol / liter, and the pH was adjusted by using hydrochloric acid and an aqueous sodium hydroxide solution (both at a concentration of 0.1 mol / liter). AC electrolytic treatment was performed under the electrolytic conditions shown in Tables 1 and 2 to form a porous aluminum oxide film layer and a barrier-type aluminum oxide film layer. At the same time, it was subjected to an atmospheric environment exceeding 150 ° C under the conditions shown in Tables 1 and 2. Of exposure. In Comparative Example 11, the atmospheric environment temperature was set to less than 150 ° C. In Comparative Example 12, no exposure to gaseous environment was performed. In the table, "elapsed time to reach 150 ° C after the AC electrolysis step" refers to the time taken until the surface of the aluminum material reaches 150 ° C, starting from the time point when the voltage application of the electrolytic treatment has been stopped. According to the above, a test material is prepared in which an oxide film composed of a porous aluminum oxide film layer and a barrier-type aluminum oxide film layer is formed on one side of the aluminum material.

[Table 1]

[Table 2]

Next, the test materials prepared in the above manner were subjected to cross-sectional observation by TEM and water content measurement by TDS-MS. In the TEM section observation, in order to determine the thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer, and the pore diameter of the porous aluminum oxide film layer, a thin section slice was prepared from a test material using an ultra-thin slicer. Sample. Next, the thin sample was observed with a TEM cross section, and the thickness of the porous aluminum oxide film layer and the barrier aluminum oxide film layer and the porous aluminum oxide film were measured at each of 10 points in the observation field (1 μm × 1 μm). The pinhole diameter of the layer was determined by taking each arithmetic mean as the measurement result. In the TDS-MS measurement, the temperature increase rate was set to 30 ° C / min, and the temperature was increased to 620 ° C to measure the amount of water molecules present per unit area.

In addition, in order to check the total thickness variation of the porous aluminum oxide film and the barrier-type aluminum oxide film on the entire surface of the test material, an additional cross-sectional TEM observation was performed. That is, it is different from the previously prepared thin sample. In the same way, another 9 thin sample samples were made by the ultra-thin microtome. Then, the thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer was measured at 10 points for the 9 thin sample samples. Next, from the measurement results of the thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer of a total of 100 points of all the above-mentioned thin sample samples, the porous aluminum oxide film layer and the barrier-type aluminum oxide film at each point were measured. The thicknesses of the layers are added to obtain the total thickness, which is the thickness of the oxide film at each point. The maximum, minimum, and arithmetic mean values of the thickness of the oxide film at 100 points obtained in this way are shown in the columns of "the overall thickness of the oxide film" in Tables 3 and 4. In addition, it is also checked whether the fluctuation range of the oxide film thickness at these 100 points is within ± 50% of the arithmetic mean. Specifically, when the arithmetic average value is T (nm), all the total thicknesses including the maximum value and the minimum value are considered to be ○ when they are in the range of (0.5 × T) to (1.5 × T). Is ×.

[table 3]

[Table 4]

Moreover, the existence rate of the polar functional group in the resin was evaluated. That is, the infrared absorption spectrum of the resin was measured using a Fourier transform type spectro hardness tester having a measurement wave number range of 4000 cm ^-1 to 650 cm ^-1 and a decomposition energy of 1 cm ^-1 . Next, the area of the measured infrared absorption spectrum and the wave number range in which the spectrum appears and the area surrounded by the horizontal axis are numerically integrated using a trapezoid method at intervals of 1 cm ^-1 . The obtained integrated value was substituted into Equation 1 to calculate the value, thereby evaluating the existence rate of the polar functional group in the resin. The results are shown in Tables 5-7.

Moreover, the adhesiveness using the adhesive was evaluated about the said test material by the following method.

[One adhesion test]

Two pieces prepared from the above test materials were cut to a length of 50 mm and a width of 25 mm. The two surface-treated surfaces of the two test materials are overlapped with each other along the total width direction and the length direction by 10 mm, and a resin layer is sandwiched therebetween. Prepare joints. The resin used for the resin layer is selected from commercially available two-component epoxy adhesives (main agent = modified epoxy resin, hardener = modified polyimide, weight mixing ratio = main agent 100 / hardener 100 ), Polyethylene, polyester and ethylene-methacrylic acid copolymer resins or mixtures thereof. A shear test piece of such an assembly was prepared. At the speed of 100 mm / min, each end of the longitudinal direction of the two pieces of test material was stretched in the opposite direction in the longitudinal direction by a tensile tester. Assess adhesion. In addition, the shear test piece was prepared from the same test material in 10 groups and evaluated each.

○: Shear stress is 20 N / mm ² or more, and the adhesive layer itself is in a state of cohesive failure.

△: Although the shear stress is 20 N / mm ² or more, the interface between the adhesive layer and the test material is peeled off

×: Shear stress is less than 20 N / mm ² and the interface between the adhesive layer and the test material is peeled off

The results are shown in Tables 5 and 6. In the same table, the numbers of the above-mentioned ○, △, and × in each of the 10 test pieces are displayed, and when all of them are ○, it is judged to be a pass;

[table 5]

[TABLE 6]

[TABLE 7]

[Long-term stability test]

A shear test piece similar to the one adhesion test was prepared, and after being left in an environment of 85 ° C. for 2000 hours, the same test as the one adhesion test was performed, and each was evaluated.

○: Shear stress is 20 N / mm ² or more, and the adhesive layer itself is in a state of cohesive failure.

△: Although the shear stress is 20 N / mm ² or more, the interface between the adhesive layer and the test material is peeled off

×: Shear stress is less than 20 N / mm ² and the interface between the adhesive layer and the test material is peeled off

The results are shown in Tables 5 and 6. In the same table system, the number of the above-mentioned ○, △, and × in each of the 10 test pieces is displayed, but the case where ○ is 5 or more and × is 0 is judged as a pass, and the cases other than that are judged as unacceptable.

In Examples 1 to 33, since the oxide film met the requirements of the present invention, both primary adhesion and long-term stability were judged to be acceptable. On the other hand, in Comparative Examples 1 to 12, it was judged to be unacceptable for the following reasons.

In Comparative Example 1, since the pH of the electrolytic solution was too low during the AC electrolytic treatment, the alkali etching power was insufficient. Therefore, the pore diameter of the porous aluminum oxide film layer is insufficient, and the primary adhesion and long-term stability are unqualified.

In Comparative Example 2, since the pH of the electrolytic solution was too high during the AC electrolytic treatment, the alkali etching force became excessive. Therefore, the thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer is insufficient, so there is no effect of dissolving aluminum, and the variation range of the total thickness cannot converge within ± 50%. In addition, the pore diameter of the porous aluminum oxide film layer was too large. As a result, the primary adhesion and long-term stability were unsatisfactory.

In Comparative Example 3, since the temperature of the electrolytic solution was too low during the AC electrolytic treatment, the alkali etching force was insufficient. Therefore, the porous aluminum oxide film layer has incomplete porous structure, insufficient small pore diameter, and unsatisfactory primary adhesion and long-term stability.

In Comparative Example 4, since the temperature of the electrolytic solution was too high during the AC electrolytic treatment, the alkali etching force was excessive. Therefore, porous aluminum coatings and barriers The thickness of the wall-type aluminum oxide film layer is insufficient, so there is no effect of dissolving aluminum, and the fluctuation range of the total thickness cannot converge within ± 50%. As a result, the primary adhesion and long-term stability were unsatisfactory.

In Comparative Example 5, since the frequency of the AC electrolytic treatment is too low, the electrical state is approximately DC electrolytic. Therefore, the formation of the porous aluminum oxide film layer cannot be performed, and the thickness of the barrier aluminum oxide film layer becomes too large. Therefore, the primary adhesion and long-term stability were unsatisfactory.

In Comparative Example 6, since the frequency was too high in the AC electrolytic treatment, the anode and cathode reversed too quickly. Therefore, the formation of the porous aluminum oxide film layer is extremely slow, its thickness is insufficient, and the primary adhesion and long-term stability are unqualified.

In Comparative Example 7, since the current density was too low during the AC electrolytic treatment, a barrier-type aluminum oxide film layer was preferentially formed. Therefore, the thickness of the porous aluminum oxide film layer is insufficient, and the primary adhesion and long-term stability are unacceptable.

In Comparative Example 8, since the current density was too high in the AC electrolytic treatment, electric sparks or the like were generated in the electrolytic solution during the electrolytic treatment, and the control became unstable. Therefore, the oxide film is formed as a whole in excess, and the thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer is too large. On the other hand, the total thickness of the oxide film is extremely reduced.爰 There is no effect of dissolving aluminum, and the fluctuation range of the total thickness cannot converge within ± 50%. As a result, the primary adhesion and long-term stability were unacceptable.

In Comparative Example 9, since the electrolytic treatment time was too short in the AC electrolytic treatment, the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer were not present. Law is fully formed. Therefore, the thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer is insufficient, and the primary adhesion and long-term stability are unqualified.

In Comparative Example 10, since the electrolytic treatment time was too long in the AC electrolytic treatment, the entire oxide film was excessively formed. Therefore, the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer become too thick, and the primary adhesion and long-term stability are unacceptable.

In Comparative Examples 11 and 12, since the shapes of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer satisfy the requirements of the present invention, the primary adhesion is good. However, since the temperature of the gas environment exposure after the electrolytic treatment in Comparative Example 11 was too low, and the gas environment exposure was not performed in Comparative Example 12, the moisture contained in the oxide film could not be removed, and the long-term stability was unacceptable.

Industrial availability

According to the present invention, it is possible to stably obtain a surface-treated aluminum material covering the entire surface of the aluminum material, which is excellent in adhesion and adhesion, and can maintain this characteristic for a long period of time, and a bonded body with the resin layer using the same.

Claims (7)

A surface-treated aluminum material, comprising: an aluminum material and an oxide film formed on at least one of the surfaces thereof; the oxide film is composed of a porous aluminum oxide film layer formed on the surface side and having a thickness of 20 to 500 nm; and A barrier-type aluminum oxide film layer with a thickness of 3 to 30 nm is formed on the substrate side, small holes having a diameter of 5 to 30 nm are formed in the porous aluminum oxide film layer, and the moisture content in the oxide film is 10 μg / cm ² or less. For example, the surface-treated aluminum material of claim 1, wherein the variation in the total thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer is within ± 50% of the arithmetic mean of the total thickness. A method for manufacturing a surface-treated aluminum material is a method for manufacturing a surface-treated aluminum material as described in claim 1, characterized in that a surface-treated aluminum material electrode and a counter electrode are used, with a pH of 9 to 13 and a liquid temperature of 35 to 85 ° C. An alkaline aqueous solution is used as an electrolytic solution, and an alternating current electrolytic treatment is performed under the conditions of a frequency of 10 to 100 Hz, a current density of 4 to 50 A / dm ² and an electrolysis time of 5 to 300 seconds. An oxide film is formed on the surface, and the time from the end of the AC electrolytic treatment to the surface temperature of the aluminum material where the oxide film is formed when exposed to a gas environment exceeding 150 ° C is within 24 hours. The method for manufacturing a surface-treated aluminum material according to claim 3, wherein the electrolytic solution of the aforementioned alkaline aqueous solution contains 5 ppm or more and 1000 ppm or less of dissolved aluminum. For example, if the method for manufacturing a surface-treated aluminum material according to claim 3 or 4 makes the thickness of the porous aluminum oxide film layer L (nm) and the gas environment temperature T (° C), the aforementioned exposure to a gas environment exceeding 150 ° C The time t (second) satisfies the relationship of t ≧ 20 × (L / T). For example, the method for manufacturing a surface-treated aluminum material according to claim 3 or 4, wherein the relative humidity of the aforementioned gas environment is 50% or less. A bonded body of a surface-treated aluminum material / resin layer, characterized in that a resin layer is bonded to the surface-treated surface of the surface-treated aluminum material as claimed in claim 1 or 2, wherein the resin of the resin layer has a material selected from the group consisting of amine groups, At least one kind of polar functional group of amine group, ester group, carboxyl group, epoxy group and hydroxyl group, and in the infrared absorption spectrum of the resin, when the absorptivity at wave number ν cm ^-1 is expressed as I (ν) , The following formula 1 is 0.01 or more and 3.0 or less: