KR102098576B1 - Surface treated aluminum material, method for producing same, and resin-coated surface treated aluminum material - Google Patents

Abstract

[Problem] A surface-treated aluminum material having excellent adhesion and adhesion over the entire surface of an aluminum material and a method of manufacturing the same are provided.
[Solutions] As an aluminum material having an oxide film formed on at least one surface, the oxide film is a porous aluminum oxide film layer having a thickness of 20 to 500 nm formed on the surface side and a barrier aluminum oxide film layer having a thickness of 3 to 30 nm formed on the substrate side. Made, a small hole with a diameter of 5 to 30 nm is formed in the porous aluminum oxide layer, and the variation width of the total thickness of the porous aluminum oxide layer and the barrier aluminum oxide layer on the entire surface of the aluminum material is the total. A surface-treated aluminum material characterized in that it is within ± 50% of the arithmetic mean of the thickness, and a method for manufacturing the same.

Description

SURFACE TREATED ALUMINUM MATERIAL, METHOD FOR PRODUCING SAME, AND RESIN-COATED SURFACE TREATED ALUMINUM MATERIAL}

The present invention relates to an aluminum material subjected to surface treatment, a method for manufacturing the same, and a resin-coated surface-treated aluminum material. Specifically, the surface-treated aluminum material having an aluminum oxide film on the surface and excellent adhesion and stability thereof It relates to a method of manufacturing and a resin-coated surface-treated aluminum material using a surface-treated aluminum material.

Pure aluminum materials or aluminum alloy materials (hereinafter referred to as "aluminum materials") are lightweight, have suitable mechanical properties, and have excellent characteristics such as aesthetics, moldability, corrosion resistance, and the like. It is widely used in machine parts and so on. While these aluminum materials are used as they are, they are often used by adding and improving functions such as corrosion resistance, abrasion resistance, resin adhesion, hydrophilicity, water repellency, antibacterial properties, design properties, infrared radiation properties, and high reflection properties by performing various surface treatments. .

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

Moreover, the alkali alternating current electrolysis method like patent document 1 is proposed as the surface treatment method which improves resin adhesiveness especially. That is, by using an alkaline solution having a bath temperature of 40 to 90 ° C, an alternating current electrolytic treatment is performed at a current density of 4 to 50 A / dm2 for a time when the amount of electricity exceeds 80 C / dm2. By this, it is said that an aluminum alloy coating plate for a can lid having an oxide film having a thickness of 500 to 5000 angstroms is obtained.

However, even when the technique of Patent Document 1 was used and the treatment was performed under the same electrolytic conditions, there were cases where the adhesion was extremely low depending on the timing of the electrolytic treatment. Specifically, it was said that a part of the surface of the aluminum material exhibited a change in color tone (many of dark brown or cloudy white), and the adhesion of the part was extremely low.

Japanese Patent Application Publication No. Hei 3-229895

Aluminum Handbook, 7th edition, pages 179-190, 2007, Japan Aluminum Association Japanese Industrial Standard JIS H8601, 「Anodized film of aluminum and aluminum alloy」 (1999)

An object of the present invention is to provide a surface-treated aluminum material excellent in adhesiveness and adhesion over the entire surface of the aluminum material, a stable method for manufacturing such a surface-treated aluminum material, and a resin-coated surface-treated aluminum material using the surface-treated aluminum material.

As a result of repeated examinations to solve the above problems, the present inventors have optimized the fluctuation range of the total thickness of the porous aluminum oxide coating layer and the barrier aluminum oxide coating layer on the entire surface of the aluminum material. It was found that it was effective to control the concentration of dissolved aluminum contained in the electrolytic treatment liquid used in the alkaline alternating current electrolytic treatment in order to prevent the occurrence of unevenness in the formation of the oxide film on the entire surface of the aluminum material. .

That is, in the first aspect, the present invention is an aluminum material having an oxide film formed on at least one surface, wherein the oxide film has a thickness of 20 to 500 nm formed on the surface side and a thickness of the porous aluminum oxide film layer and the substrate side. It is made of a barrier aluminum oxide film layer of 3 to 30 nm, and a small hole having a diameter of 5 to 30 nm is formed in the porous aluminum oxide film layer, and the porous aluminum oxide film layer and the barrier aluminum on the entire surface of the aluminum material The surface-treated aluminum material was characterized in that the fluctuation width of the total thickness with the oxide film layer was within ± 50% of the arithmetic mean value of the total thickness.

In the first aspect of the present invention, when the surface-treated aluminum material was bent 180 degrees with 5R so that the oxide film side was convex, it was assumed that the aluminum substrate had an exposure rate of 5% or less.

In addition, the second aspect of the present invention is a method of manufacturing a surface-treated aluminum material in the first aspect, using an electrode of a surface-treated aluminum material and a counter electrode, and the temperature of the liquid at pH 9-13. Alkaline aqueous solution having a dissolved aluminum concentration of 5ppm or more and 1000ppm or less as an electrolytic solution at 80 ° C, and an alternating current electrolytic treatment under conditions of a frequency of 20 to 100Hz, a current density of 4 to 50A / d㎡ and an electrolysis time of 5 to 60 seconds By doing so, an oxide film was formed on the surface of the aluminum material facing the counter electrode to produce a surface-treated aluminum material manufacturing method.

In the second aspect of the present invention, it is assumed that the counter electrode is a graphite electrode.

Further, in the second aspect of the present invention, it is assumed that both the electrode and the counter electrode of the aluminum material to be surface-treated are flat.

Moreover, in this invention, the resin-coated surface-treated aluminum material of Claim 6 characterized by coating the surface of the oxide film of the surface-treated aluminum material of Claim 1 or 2 with a resin layer.

According to the present invention, since an oxide film having high adhesion and high adhesion to a resin or the like is uniformly formed on the surface of the aluminum material, it is possible to stably obtain a surface-treated aluminum material having excellent adhesion and adhesion over the entire surface of the aluminum material.

Specifically, the oxide film on the surface of the aluminum material has a two-layer structure between a porous aluminum oxide film layer and a barrier aluminum oxide film layer. And, by the porous aluminum oxide film layer having a thickness of 20 to 500 nm formed on the surface side of the aluminum material and having a small hole with a diameter of 5 to 30 nm, adhesion is achieved by increasing its surface area while suppressing its own cohesive failure. Improves. In addition, the barrier-type aluminum oxide film layer having a thickness of 3 to 30 nm formed on the substrate side of aluminum combines the aluminum substrate and the porous aluminum oxide film layer while suppressing its own cohesive failure, thereby improving adhesion and adhesion. In addition, by setting the fluctuation range of the total thickness of the oxide film on the entire surface of the aluminum material to within ± 50% of the arithmetic average value of the total thickness, excellent adhesion and adhesion to the resin layer, etc. to be bonded over the entire surface of the aluminum material. This is exerted.

The aluminum material obtained in this way can obtain extremely high adhesive strength when various adhesives based on the existing technology are used for the resin layer due to its excellent adhesiveness. Moreover, due to its excellent adhesion, various paints based on the existing technology, specifically water-based paints, solvent-borne paints, powder paints, electrodeposition paints, etc., are used as the base treatment when coating as the resin layer. In this case, an extremely large coating film adhesion strength is obtained.

Specifically, by using a resin-coated surface-treated aluminum material as a joined body comprising a resin layer such as a thermoplastic resin or a thermosetting resin on the surface of the oxide film of the surface-treated aluminum material of the present invention, it has been extended than in the past and used for various purposes as an aluminum material. Can be used. For example, recently, the use as a printed wiring board which paid attention to the high thermal conductivity which an aluminum plate has is mentioned. That is, with the recent miniaturization and weight reduction of electrical and electronic devices, the printed wiring board has been required to have multiple layers, higher integration, and higher density than conventional ones. In addition, in a substrate using a conventional insulator, heat generated from electronic components mounted at high density cannot be dissipated, resulting in destabilization of the circuit. On the other hand, by employing an aluminum plate excellent in thermal conductivity as a substrate, cooling of electronic components by the substrate itself can be achieved, and the performance of the entire circuit can be improved.

Such a printed wiring board is manufactured by attaching a metal foil such as copper foil to an aluminum plate. At this time, an epoxy resin, a polyimide resin, or the like is used as the adhesive. Then, by using the resin-coated surface-treated aluminum material which coated the resin layer as the adhesive on the surface of the oxide film of the surface-treated aluminum material of the present invention, the surface-treated aluminum material and the resin layer were interposed by the interposition of the oxide film of the specific structure. It is possible to bond the aluminum material and the metal foil by the resin layer, while improving the adhesion with the superfine.

Further, in the manufacturing method according to the present invention, the surface-treated aluminum material can be stably manufactured by appropriately setting the AC electrolytic treatment conditions.

1 is a schematic view of a surface-treated aluminum material according to the present invention.

Hereinafter, the details of the present invention will be described in order. 1, in the surface-treated aluminum material 1 according to the present invention, an oxide film 2 is formed on one surface, and the oxide film 2 is a porous aluminum oxide film layer 3 formed on the surface side. ) And the barrier-type aluminum oxide film layer 4 formed on the substrate 5 side. Then, a small hole 31 is formed in the porous aluminum oxide coating layer 3.

A. Aluminum material

As the aluminum material used in the present invention, pure aluminum or an aluminum alloy is used. There are no particular restrictions on the components of the aluminum alloy, and various alloys including alloys specified in JIS can be used. The shape is not particularly limited, but since it is stable and can form a treatment film, a flat plate shape is suitably used. Although the plate thickness can be appropriately selected depending on the application, 0.05 to 2.0 mm is preferred, and 0.1 to 1.0 mm is more preferable from the viewpoint of weight reduction and formability.

B. Oxide film

On the surface of the aluminum material used in the present invention, a porous aluminum oxide coating layer formed on the surface side and a barrier aluminum oxide coating layer formed on the substrate side are provided. That is, an oxide film composed of two layers of a porous aluminum oxide film layer and a barrier aluminum oxide film layer is formed on the surface of the aluminum material. While the porous aluminum oxide layer exerts strong adhesion and adhesion, the entire aluminum oxide layer and the aluminum substrate are firmly bonded by the barrier aluminum oxide layer.

B-1. Porous aluminum oxide layer

The thickness of the porous aluminum oxide coating layer is 20 to 500 nm. When the thickness is less than 20 nm, the thickness is not sufficient, so that formation of a small hole structure described later tends to be insufficient, and adhesion and adhesion decrease. On the other hand, when it exceeds 500 nm, the porous aluminum oxide coating layer itself tends to be cohesively destroyed, resulting in a decrease in adhesion and adhesion.

As shown in Fig. 1, the porous aluminum oxide coating layer 3 has small holes 31 facing the depth direction from its surface. The diameter of the small hole is 5 to 30 nm, and preferably 10 to 20 nm. This small hole exerts an effect of increasing the contact area with the aluminum oxide film, such as a resin layer or an adhesive, and increasing the adhesive force and adhesion. If the diameter of the small hole is less than 5 nm, sufficient contact strength or adhesion cannot be obtained because the contact area is insufficient. On the other hand, when the diameter of the small hole exceeds 30 nm, the entire porous aluminum oxide coating layer weakens, causing cohesive failure, and the adhesion and adhesion are reduced.

The ratio of the total pore area of the small hole to the surface area of the porous aluminum oxide coating layer is not particularly limited. The ratio of the total pore area of the small hole to the apparent surface area of the porous aluminum oxide film layer (area expressed by multiplication of length and width without taking into account minute irregularities of the surface, etc.) is preferably 25 to 75%. If it is less than 25%, the contact area may be insufficient, and sufficient adhesion or adhesion may not be obtained. On the other hand, when it exceeds 75%, the entire porous aluminum oxide coating layer becomes weak, causing cohesive failure, and the adhesive strength or adhesive strength may decrease.

B-2. Barrier type aluminum oxide film layer

The thickness of the barrier aluminum oxide film layer is 3 to 30 nm. When the thickness is less than 3 nm, sufficient bonding strength cannot be imparted to the bonding between the porous aluminum oxide coating layer and the aluminum substrate as an intervening layer, and in particular, the bonding strength in harsh environments such as high temperature and high humidity is insufficient. On the other hand, when it exceeds 30 nm, the barrier-type aluminum oxide coating layer tends to be cohesively destroyed due to its compactness, and the adhesion and adhesion are lowered.

B-3. The fluctuation range of the entire thickness of the oxide

The total thickness of the oxide film, that is, the sum of the thickness of the porous aluminum oxide film layer described in B-1 and the barrier aluminum oxide film layer described in B-2, is within ± 50% of the fluctuation range even when measured at any place in the aluminum material. Must be, preferably within ± 20%. That is, the average thickness of the entire thickness of the oxide film measured at arbitrary plural places on the surface of the aluminum material (preferably at least 10 points, and preferably at least 10 points at each of these points) is set to T (nm). In the case, it is necessary that the total thickness of the oxide film in all of these multiple measurement points is in the range of (0.5 x T) to (1.5 x T). When a location less than (0.5 x T) exists, the oxide film at that location becomes thinner than the surroundings. If so, in this thin portion, a gap is easily generated between the adhesive to be adhered, the resin layer to be adhered, and the oxide film, and a sufficient contact area cannot be secured, resulting in a decrease in adhesion or adhesion.

On the other hand, if a location exceeding (1.5 x T) exists, the oxide film at that location becomes thicker than the surroundings. If so, in this thick location, stress in the resin layer or the like to be in close contact is concentrated, causing cohesive failure in the oxide film, and the adhesion and adhesion are reduced.

On the other hand, since the optical properties of the above-mentioned oxide film are thinner or thicker than those in the surroundings, the optical properties are different, and it may be possible to visually observe it as a change in color tone, such as dark brown or white turquoise.

B-4. flexibility

When the surface-treated aluminum material according to the present invention is used for a printed wiring board or the like, it may be used in a curved state. Generally, when the aluminum material is bent, cracks are likely to occur in the oxide film on the surface. The oxide film of the surface-treated aluminum material according to the present invention has the above-mentioned specific structure, so that the oxide film is hardly agglomerated and destroyed, and is excellent in flexibility. Therefore, even if the surface-treated aluminum material is used in a bent state, crack generation of the oxide film is suppressed.

Such flexibility can be evaluated, for example, as an exposure rate of an aluminum substrate based on crack generation in the oxide film layer when the surface-treated aluminum material is bent 180 degrees at 5R so that the oxide film side is convex. Specifically, by setting the total length of crack generation in the bent portion to L and dividing it by the total length of bending T, (L / T) x 100 (%) is the exposure rate of the aluminum substrate based on crack generation. will be. In this case, in order not to interfere with the adhesion of the oxide film layer, the exposure rate based on crack generation is preferably 5% or less, and more preferably 2% or less.

C. Manufacturing method

As one method for manufacturing a surface-treated aluminum material having an oxide film satisfying the above conditions on the surface, an electrode of a surface-treated aluminum material and an electrode of the following material are used as a counter electrode, and pH 9 to 13 The temperature of the liquid is 35 ~ 80 ℃, and an alkaline aqueous solution having a dissolved aluminum concentration of 5ppm or more and 1000ppm or less is used as an electrolytic solution, with a frequency of 20 ~ 100Hz, a current density of 4 ~ 50A / d㎡ and an electrolysis time of 5 ~ 60 seconds. A method of forming an oxide film on the surface of the aluminum material facing the counter electrode by performing an alternating current electrolytic treatment under the conditions of is mentioned.

In the alternating current electrolytic treatment step, the aqueous alkali solution used as the electrolytic solution includes phosphates such as sodium phosphate, potassium hydrogen phosphate, sodium pyrophosphate, potassium pyrophosphate and sodium metaphosphate; and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. ; Carbonates such as sodium carbonate, sodium hydrogen carbonate and potassium carbonate; ammonium hydroxide; or an aqueous solution of these mixtures can be used. Since it is necessary to maintain the pH of the electrolytic solution in a specific range as described later, it is preferable to use an alkaline aqueous solution containing a phosphate-based material that can expect a buffer effect. The concentration of the alkali component is adjusted so that the pH of the electrolytic solution becomes a desired value, but is usually 1 × 10 ^-4 to 1 mol / liter. On the other hand, surfactants may be added to these alkaline aqueous solutions in order to improve the ability to remove contaminants.

The pH of the electrolytic solution needs to be 9 to 13, and preferably 9.5 to 12. When the pH is less than 9, the porous structure of the porous aluminum oxide coating layer is incomplete because the alkali etching power of the electrolytic solution is insufficient. On the other hand, when the pH exceeds 13, the alkali etching power becomes excessive, so that the porous aluminum oxide coating layer becomes difficult to grow, and the formation of the barrier aluminum oxide coating layer is also inhibited.

The electrolytic solution temperature needs to be 35 to 80 ° C, and preferably 40 to 70 ° C. When the temperature of the electrolytic solution is less than 35 ° C, the porous etching structure of the porous aluminum oxide coating layer is incomplete because the alkali etching power is insufficient. On the other hand, when the temperature exceeds 80 ° C, the alkali etching power becomes excessive, and thus, growth of both the porous aluminum oxide coating layer and the barrier aluminum oxide coating layer is inhibited.

The dissolved aluminum concentration contained in the electrolytic solution needs to be 5 ppm or more and 1000 ppm or less. When the dissolved aluminum concentration is less than 5 ppm, the formation reaction of the oxide film at the initial stage of the electrolytic reaction occurs rapidly, and thus it is susceptible to unevenness in the treatment process (such as contamination of the aluminum material surface or adhesion of the aluminum material). . As a result, a locally thick oxide film is formed. On the other hand, when the concentration of dissolved aluminum exceeds 1000 ppm, the viscosity of the electrolytic solution increases, and uniform convection in the vicinity of the surface of the aluminum material is prevented in the electrolytic process, and at the same time, the dissolved aluminum acts in a direction to suppress film formation. As a result, a locally thin oxide film is formed. When the concentration of dissolved aluminum is outside the above range, it is difficult to make the variation width of the total thickness of the oxide film on the entire surface of the aluminum material within ± 50% of the arithmetic mean value of the total thickness. As a result, there is a case where a decrease in the adhesion and adhesion of the resulting oxide film or good flexibility in bonding with the resin layer may not be obtained.

In alkaline alternating electrolysis, the thickness of the entire oxide film including the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer is controlled by the electric quantity, that is, the product of the current density and the electrolysis time. Basically, the more the amount of electricity, the greater the thickness of the entire oxide film. Increases. From this viewpoint, the alternating current electrolytic conditions of the porous aluminum oxide coating layer and the barrier-type aluminum oxide coating layer are as follows.

The frequency used is 20 to 100 Hz. Below 20 Hz, as a result of the increase in the direct current element for electrolysis, formation of the porous structure of the porous aluminum oxide coating layer does not proceed, resulting in a dense structure. On the other hand, when it exceeds 100 Hz, since the inversion of the anode and the cathode is too fast, the formation of the entire oxide film is extremely slow, and both the porous aluminum oxide film layer and the barrier aluminum oxide film layer require extremely long time to obtain a predetermined thickness. It is done.

The current density needs to be 4 to 50 A / d㎡. If the current density is less than 4A / dm 2, a porous aluminum oxide coating layer cannot be obtained because only the barrier aluminum oxide coating layer is preferentially formed. On the other hand, when it exceeds 50A / dm2, the current becomes excessive, and thus it is difficult to control the thickness of the porous aluminum oxide coating layer and the barrier-type aluminum oxide coating layer, and treatment unevenness tends to occur.

The delivery time needs to be 5 to 60 seconds. This is because the formation of the porous aluminum oxide coating layer and the barrier-type aluminum oxide coating layer is too rapid at a treatment time of less than 5 seconds, because any oxide coating layer is not sufficiently formed and becomes an oxide coating composed of amorphous aluminum oxide. On the other hand, when it exceeds 60 seconds, the porous aluminum oxide coating layer and the barrier-type aluminum oxide coating layer become too thick or re-dissolved, and productivity decreases.

One of the pair of electrodes used for the alternating current electrolytic treatment is an aluminum material to be surface-treated by electrolytic treatment. As the other counter electrode, a known electrode such as graphite, aluminum, or titanium electrode can be used, but in the present invention, it is excellent in conductivity without deterioration with respect to the alkali component and temperature of the electrolytic solution, In addition, it is necessary to use a material that does not cause an electrochemical reaction itself. In this regard, a graphite electrode is suitably used as the counter electrode. In addition to the fact that the graphite electrode is chemically stable and readily available at low cost, since the electric force line diffuses properly in the alternating current electrolytic process by the action of many pores present in the graphite electrode, the porous aluminum oxide coating layer and barrier This is because all of the aluminum oxide film layers tend to be more uniform.

In the present invention, a flat plate is used for both the aluminum material and the counter electrode to be electrolytically treated, and the vertical and horizontal dimensions of the surfaces of the opposite aluminum material and the counter electrode are substantially the same, and both electrodes are electrostatically stopped. It is preferable to perform the operation. In this case, an oxide film is formed on the surface of the aluminum material facing the counter electrode. Here, in order to form an oxide film on the other surface not facing the counter electrode, an oxide film is formed on one surface to end the alternating current electrolytic treatment, and then, the other surface is disposed to face the counter electrode. Similarly, an alternating current electrolytic treatment may be performed.

In addition, even when the shape of the aluminum material is a rod shape or a rectangular material other than a plate material, the surface that was not opposed to the counter electrode in the electrolytic process is repositioned so as to face the counter electrode, and the electrolytic process is repeated to oxidize the desired surface. A film can be formed.

In the structure observation and thickness measurement of the porous aluminum oxide coating layer and the barrier aluminum oxide coating layer in the present invention, cross-sectional observation by a transmission electron microscope (TEM) is suitably used. Specifically, the thickness of the porous aluminum oxide coating layer and the barrier aluminum oxide coating layer and the diameter of the small pores in the porous aluminum oxide coating layer can be measured by preparing a thin sample with an ultra microtome and TEM observation.

D. Resin coating surface treatment Aluminum material

By further coating a resin layer on the treated surface of the surface-treated aluminum material of the present invention and making it a resin-coated surface-treated aluminum material, it can be used for more applications. Here, as the resin layer, either a thermosetting resin or a thermoplastic resin may be used, and various effects can be imparted in addition to the oxide film having a specific structure specified in the present invention. Usually, the bonding material between the aluminum material and the resin layer has a larger thermal expansion coefficient of the resin than the aluminum material, so that it is easily peeled off at the interface between the aluminum material and the resin layer, and damages such as cracks and tears are likely to occur. However, the resin-coated surface-treated aluminum material according to the present invention has a thin oxide film of the surface-treated aluminum material and has a specific structure, so it is excellent in flexibility and easy to follow the expansion of the resin layer, and the interface between the aluminum material and the resin layer It is equipped with features that the damage is unlikely to occur.

The occurrence of such damage can be evaluated according to the size of the electric resistance by, for example, the presence of an electrolytic aqueous solution in a peeling portion generated when the resin-coated surface-treated aluminum material is bent 180 degrees with 5R to make the resin layer convex. . The greater the damage to the peeling portion, the smaller the electrical resistance is due to the electrolytic aqueous solution.

The resin-coated surface-treated aluminum material using a thermoplastic resin as the resin layer can be suitably used as a lightweight and highly rigid composite material. As a method for forming the resin layer, the heated thermoplastic resin is brought into a fluid state, and the thermoplastic resin layer is cooled and solidified by contacting and penetrating the porous aluminum oxide coating layer. Alternatively, a thermoplastic resin film may be laminated on the surface-treated aluminum material. Examples of the thermoplastic resin include polyolefins such as polyethylene and polypropylene; Polyvinyl chloride; polyesters such as polyethylene terephthalate and polybutylene terephthalate; Polyamide; polyphenylene sulfide; Aromatic polyether ketones such as polyether ether ketone and polyether ketone; polystyrene; Fluorine resins such as polytetrafluoroethylene and polychlorotrifluoroethylene; Acrylic resins such as methyl polymethacrylate; ABS resin; polycarbonate; Thermoplastic polyimide or the like can be used. The resin-coated surface-treated aluminum material coated with such a thermoplastic resin can be used for various moving bodies that require light weight and high rigidity, specifically, as components for aerospace and space, automobiles, ships, and railroad vehicles.

The resin-coated surface-treated aluminum material using a thermosetting resin as the resin layer can be suitably used as a printed wiring board application. As a method for forming the resin layer, the thermosetting resin is brought into a fluid state, it is brought into contact with and penetrated into the porous aluminum oxide coating layer, and then the thermosetting resin is cured by heating. As a thermosetting resin, Phenol resin; Epoxy resins such as bisphenol A type and novolac type; Melamine resin; Urea resin; Unsaturated polyester resins; Alkyd resin; Polyurethane; Thermosetting polyimide or the like can be used.

Meanwhile, the thermoplastic resin and the thermosetting resin may be used as a single resin or as a polymer alloy in which two or more kinds are mixed. In addition, by adding various fillers to the thermoplastic resin and the thermosetting resin, physical properties such as the strength and thermal expansion coefficient of the resin can be improved. Examples of such fillers include various fibers such as glass fibers, carbon fibers, and aramid fibers; Inorganic substances such as calcium carbonate, magnesium carbonate, silica, talc, and glass; Known substances such as clay can be used.

Example

Hereinafter, preferred embodiments of the present invention will be specifically described based on Examples and Comparative Examples.

Examples 1-15 and Comparative Examples 1-13

As the aluminum material, a JIS5052-H34 alloy plate having a length of 200 mm × width of 400 mm × plate thickness of 1.0 mm was used. This aluminum alloy plate was used for one electrode, and a graphite plate or a titanium plate having a flat plate shape of 300 mm long x 500 mm wide x 2.0 mm thick was used as the counter electrode. One side of the aluminum alloy plate was faced to the counter electrode, and the positive electrode was disposed on one surface of the facing surface such that a porous aluminum oxide film layer on the surface side and a barrier aluminum oxide film layer on the substrate side were formed. An alkaline aqueous solution containing sodium pyrophosphate as a main component was used as an electrolytic solution. The alkali component concentration of the electrolytic solution was adjusted to 0.5 mol / liter, and pH was adjusted with hydrochloric acid and an aqueous sodium hydroxide solution (all concentrations of 0.1 mol / liter). Under the electrolytic conditions shown in Table 1, AC electrolytic treatment was performed to form a porous aluminum oxide coating layer and a barrier aluminum oxide coating layer. On the other hand, in Comparative Example 13, an anodized sulfuric acid treatment (thickness of 2.5 µm, sealing treatment) based on the prior art was performed in place of the alkaline alternating current electrolytic treatment.

[Table 1]

About the test material produced as mentioned above, sectional observation was performed by TEM. Specifically, in order to measure the thickness of the porous aluminum oxide coating layer and the barrier-type aluminum oxide coating layer and the diameter of the small pores in the porous aluminum oxide coating layer, a thin sample for cross-section observation was prepared from the test material using an ultra microtome. Then, in this lamella sample, 10 points in the observation field (1 µm × 1 µm) were selected and observed by TEM cross-section to determine the thickness of the porous aluminum oxide film layer and the barrier aluminum oxide film layer and the porous aluminum oxide film layer. The diameter of the small hole was measured at each point (first measurement). About these thickness and diameter, the arithmetic mean value of the measurement value of 10 points is shown in the 1st measurement of Table 2.

[Table 2]

Next, a second measurement was performed to investigate variations in the total thickness of the porous aluminum oxide film and the barrier aluminum oxide film on the entire surface of the test material. In this second measurement, nine additional thin-film samples were prepared from the test piece provided in the first measurement separately from the thin-film sample produced in the first measurement and in the same manner, using an ultra microtome. And the thickness of the porous aluminum oxide film layer and the barrier aluminum oxide film layer was measured 10 points about each of these nine thin-film samples similarly to 1st measurement. Then, the thicknesses of the porous aluminum oxide coating layer and the barrier aluminum oxide coating layer at each point were added from the measurement results of the thicknesses of all 100 porous aluminum oxide coating layers and barrier aluminum oxide coating layers in all 10 of the above-described flaky samples. Then, the total thickness was determined and used as the oxide film thickness at each point. The maximum value, minimum value, and arithmetic mean value in the oxide film thickness of 100 points thus obtained are shown in the second measurement in Table 2. In addition, it was also investigated whether or not the fluctuation range of the thickness of the oxide film at these 100 points was within ± 50% of the arithmetic average value. Specifically, when the arithmetic mean value is T (nm), the case where all the total thicknesses including the maximum value and the minimum value are in the range of (0.5 x T) to (1.5 x T) is set to pass (○), and the range The case not shown is set as the rejection (×) and is shown in the second measurement in Table 2.

About the test material, adhesiveness using an adhesive, adhesion to a coating film, and flexibility by a bending test were evaluated by the following methods. Moreover, evaluation of the resin-coated surface-treated aluminum material was also performed.

〔Adhesiveness evaluation〕

Two sheets of 50 mm in length and 25 mm in width were prepared from the test piece. Commercially available two-component epoxy adhesives (Topic = Modified Epoxy Resin, Curing Agent = Modified Polyimide, Weight Mixing Ratio = Topic 100 / The overlapped part was adhered by the curing agent 100) to prepare a shear test piece. Standards of the following for pulling the ends of the two specimens in the longitudinal direction in the opposite direction along the longitudinal direction at a rate of 100 mm / min by means of a tensile tester, and adhering by the load (in terms of shear stress) and peeling state It was evaluated as. On the other hand, ten test pieces were prepared from the same test piece for the shear test piece, and evaluated for each.

○: Shear stress is 20 N / m 2 or more, and the adhesive layer itself is cohesively broken.

△: Shear stress is 20 N / m㎡ or more, but the adhesive layer and the test material are intersected.

×: Shear stress is less than 20 N / m 2, and the adhesive layer and the test material are intersected.

Table 3 shows the results. In the following table, the number of groups of ○, Δ, and X among the 10 test pieces is shown, respectively, but all cases of ○ passed and were judged as failed.

[Table 3]

〔Adhesion evaluation〕

The surface of the above-mentioned test material was coated with "V-Front 2000" manufactured by Dainihon Coating Co., Ltd. and dried (160 ° C, 20 minutes) to form a resin film having a thickness of 30 µm. An adhesion test piece was produced. By a method conforming to JIS-K5600-5-6, the resin coating film of this adhesion test piece was cut into a checkerboard eye shape at a corner of 1 mm using a cutter knife. Then, after subjecting the test piece to retort immersion treatment at 125 ° C for 30 minutes, it was immediately taken out from the treatment liquid and wiped off moisture. The test piece was subjected to a peel test with a transparent pressure-sensitive adhesive tape. The adhesiveness was evaluated based on the following criteria by the coating film residual ratio. On the other hand, ten test pieces were prepared from the same test material, and the adhesion test pieces were evaluated for each.

○: 100% of film residual ratio

△: Coating film residual rate of 75% or more and less than 100%

×: Things with less than 75% coating film remaining

Table 3 shows the results. Although the number of said ○, (triangle | delta) and x among 10 test pieces is shown in the said table | piece, all the cases of ○ passed and the other was judged as failing.

〔Flexibility evaluation〕

What was cut to 50 mm in length and 25 mm in width was prepared from the test material. It was bent 180 degrees at 5R using a mold so that the oxide film formation surface was convex. Then, the bent portion was immersed in a test solution (20% aqueous copper sulfate solution) for 5 minutes, then taken out, washed with water, and dried at room temperature. When a crack occurs in the oxide film of the bent portion, copper adheres to the aluminum base of the crack. Thus, the crack-producing site was identified by visually observing the copper attachment point along the entire length of the bent portion using a loupe or Vernier caliper. Specifically, (L / 25) × 100 (%) is based on crack generation by making the total length of copper adhesion observed in the bent portion L (mm) and dividing it by the total bending length (25 mm). It was set as the exposure rate of the aluminum base. Ten test pieces were prepared from the same test piece for the flexibility test pieces, and evaluated for each to obtain the respective exposure rates of the aluminum substrate.

Table 3 shows the results. The exposure rate in the table shows the average exposure rate of 10 test pieces. Here, the exposure rate was set to 5% or less as a pass, and it was judged as failing to exceed this.

〔Evaluation of resin coated surface-treated aluminum materials〕

The surface of the above-mentioned test material was coated with "9K-564S" (aqueous acrylic resin coating) manufactured by DIC Co., Ltd. to dry it (250 ° C, 1 minute), and a resin coating film having a thickness of 2 μm (resin layer) To form a resin-coated surface-treated aluminum material. While cutting this to a length of 100 mm and a width of 30 mm, a test piece was prepared by bending 180 degrees with a 5R using a mold so that the resin layer side was convex. The bending peak of the test piece was brought into contact with a sponge having a width of 20 mm containing an aqueous 1% sodium chloride solution, and the test piece side was positive and the sponge side was negative, and a DC voltage of 6.0 V was applied for 4 seconds. The maximum current value was measured. In the case where damage such as peeling does not occur at the interface between the test material and the resin layer, no current flows because the test piece becomes an insulator. On the other hand, when a damaged portion is present, an electric current flows through the sodium chloride aqueous solution present therein. In addition, the larger the damaged portion, the greater the amount of sodium chloride solution present therein, and the lower the electrical resistance, the greater the maximum current value. When the maximum current value was less than 5 mA, no damage, such as peeling, was present or was small, and thus was passed. On the other hand, in the case of 5 mA or more, damage such as peeling was large, so that it was rejected. Table 3 shows the results.

In all of Examples 1-15, since the oxide film satisfies the provisions of the present application, the adhesion evaluation, adhesion evaluation, and flexibility evaluation of the surface-treated aluminum material and evaluation of the resin-coated surface-treated aluminum material were passed. On the other hand, in Comparative Examples 1 to 13, the failure was judged for the following reasons.

In Comparative Example 1, since the pH of the electrolytic solution in the alternating current electrolytic treatment was too low, the alkali etching power was insufficient. Therefore, the pore diameter of the porous aluminum oxide coating layer was insufficient, and adhesion, adhesion, and flexibility were unsuccessful.

In Comparative Example 2, since the pH of the electrolytic solution in the alternating current electrolytic treatment was too high, the alkali etching power was excessive. Therefore, the thickness of the porous aluminum oxide coating layer and the barrier-type aluminum oxide coating layer is insufficient, and the pore diameter of the porous aluminum coating becomes excessive, and thus the fluctuation width, adhesiveness, adhesion and flexibility of the total thickness of the oxide coating are disqualified.

In Comparative Example 3, since the temperature of the electrolytic solution in the AC electrolytic treatment was too low, the alkali etching power was insufficient. Therefore, the porous structure of the porous aluminum oxide coating layer was incomplete, and the pore size was insufficient, resulting in poor adhesion, adhesion, and flexibility.

In Comparative Example 4, since the temperature of the electrolytic solution in the AC electrolytic treatment was too high, the alkali etching power was excessive. Therefore, the thickness of the porous aluminum coating layer and the barrier-type aluminum oxide coating layer was insufficient, and the fluctuation width, adhesiveness, adhesion and flexibility of the total thickness of the oxide coating failed.

In Comparative Example 5, since the electrolytic solution in the alternating current electrolytic treatment was a completely new bath, and no dissolved aluminum was present, the formation reaction of the oxide film in the initial stage of the electrolytic reaction occurred rapidly. Therefore, a place where the oxide film was partially formed was formed, and the fluctuation width, adhesiveness, adhesiveness, and flexibility of the total thickness of the oxide film failed.

In Comparative Example 6, because the dissolved aluminum concentration of the electrolytic solution in the AC electrolytic treatment was too high, a locally thin oxide film was formed. Therefore, the fluctuation width, adhesiveness, adhesiveness and flexibility of the total thickness of the oxide film failed.

In Comparative Example 7, since the frequency in the AC electrolytic treatment was too low, the electrical state became closer to DC electrolysis. Therefore, formation of the porous aluminum oxide coating layer did not proceed, and the thickness of the barrier aluminum oxide coating layer was excessive. Therefore, adhesiveness, adhesiveness, and flexibility were unsuccessful.

In Comparative Example 8, since the frequency in the AC electrolytic treatment was too high, the inversion of the positive electrode and the negative electrode was too fast. Therefore, the formation of the porous aluminum oxide coating layer was extremely delayed, and the thickness was insufficient, resulting in failure of adhesion, adhesion, and flexibility.

In Comparative Example 9, since the current density in the AC electrolytic treatment was too low, a barrier aluminum oxide film layer was preferentially formed. Therefore, the thickness of the porous aluminum oxide coating layer was insufficient, and adhesiveness, adhesion, and flexibility were unsuccessful.

In Comparative Example 10, since the current density in the AC electrolytic treatment was too high, the control became unstable, such as sparks generated in the electrolytic solution in the electrolytic treatment. Therefore, the entire oxide film is formed excessively, and the thickness of the porous aluminum oxide film layer and the barrier-type aluminum oxide film layer is excessive, while a part in which the total thickness of the oxide film is extremely small has also occurred. As a result, the fluctuation width, adhesiveness, adhesiveness and flexibility of the total thickness of the oxide film failed.

In Comparative Example 11, because the electrolytic treatment time in the AC electrolytic treatment was too short, the porous aluminum oxide coating layer and the barrier aluminum oxide coating layer were not sufficiently formed. Therefore, the thickness of the porous aluminum oxide coating layer and the barrier-type aluminum oxide coating layer was insufficient, and adhesion, adhesion, and flexibility were unsuccessful.

In Comparative Example 12, since the electrolytic treatment time in the AC electrolytic treatment was too long, the entire oxide film was excessively formed. Therefore, the porous aluminum oxide coating layer and the barrier-type aluminum oxide coating layer became too thick, and the adhesiveness, adhesiveness, and flexibility were unsuccessful.

In Comparative Example 13, it was an anodized sulfuric acid treatment based on the prior art and did not have the oxide film structure specified in the present invention, so adhesion, adhesion, and flexibility were not acceptable.

In all of Comparative Examples 1 to 13, since the oxide film did not have the features of the present invention, the bending damage of the resin-coated surface-treated aluminum material was large, and the coating evaluation was unsuccessful.

Industrial availability

ADVANTAGE OF THE INVENTION According to this invention, the surface-treated aluminum material excellent in adhesiveness and adhesiveness over the whole surface of an aluminum material, and the resin-coated surface-treated aluminum material using this can be obtained.

1. Surface treatment aluminum material
2. Oxide film
3. Porous aluminum oxide coating layer
31. Eyelet
4. Barrier type aluminum oxide coating layer
5. Possession

Claims (6)

As an aluminum material having an oxide film formed on the surface, the oxide film is formed of a porous aluminum oxide film layer having a thickness of 20 to 500 nm formed on the surface side and a barrier aluminum oxide coating layer having a thickness of 3 to 30 nm formed on the substrate side, A small hole with a diameter of 5 to 30 nm is formed in the porous aluminum oxide film layer, and the variation width of the total thickness of the porous aluminum oxide film layer and the barrier aluminum oxide film layer on the entire surface of the aluminum material is arithmetic of the total thickness. Surface-treated aluminum material characterized in that it is within ± 50% of the average value. According to claim 1,
When the surface-treated aluminum material is bent 180 degrees with 5R so that the oxide film side is convex, the surface-treated aluminum material having an aluminum substrate with an exposure rate of 5% or less. A method for manufacturing the surface-treated aluminum material according to claim 1 or 2, wherein the electrode of the surface-treated aluminum material and a counter electrode are used, and the pH of the liquid is 35 to 80 ° C at a pH of 9 to 13, and dissolved. By using an alkaline aqueous solution having an aluminum concentration of 5ppm or more and 1000ppm or less as an electrolytic solution, and performing alternating current electrolysis under conditions of a frequency of 20 to 100Hz, a current density of 4 to 50A / dm2, and an electrolysis time of 5 to 60 seconds, it is opposed to A method of manufacturing a surface-treated aluminum material, characterized in that an oxide film is formed on the surface of the aluminum material. The method of claim 3,
Method for manufacturing a surface-treated aluminum material using the counter electrode as a graphite electrode. The method of claim 3,
A method of manufacturing a surface-treated aluminum material in which both the electrode of the surface-treated aluminum material and the counter electrode are flat. A resin-coated surface-treated aluminum material, characterized in that a resin layer is coated on the surface of the oxide film of the surface-treated aluminum material according to claim 1 or 2.

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