Surface-treated aluminum materials and their manufacturing methods

Abstract

This invention provides a surface-treated aluminum material with excellent adhesion to other materials. The surface-treated aluminum material has an aluminum material and an oxide coating formed on at least a portion of the aluminum material surface, wherein, when the perimeter of the voids on the oxide coating surface is denoted as L and the area as S, L... 2 The roughness of the gap defined by / S×(1 / 4π) is greater than 2.5.

Description

Technical Field

[0001] This invention relates to a surface-treated pure aluminum material or aluminum alloy material (hereinafter referred to as aluminum material), and more specifically, to a surface-treated aluminum material. Background Technology

[0002] Aluminum is lightweight and has moderate mechanical properties. It also has excellent aesthetics, electrical conductivity, heat dissipation, corrosion resistance, and recyclability, making it suitable for various structural components, heat exchange components, containers, packaging, electronic equipment, and machinery.

[0003] These aluminum materials are often used in applications where surface treatments are applied to some or all of them to impart or improve properties such as corrosion resistance, insulation, sealing, antibacterial properties, and wear resistance.

[0004] Furthermore, in recent years, with the automotive industry at its core, efforts have been made to promote resource conservation and energy efficiency. To achieve further weight reduction when applying aluminum to structural components, structural components that bond part or all of the aluminum material to resin have been proposed. These structural components are used in conveying equipment, thus requiring high bonding durability in atmospheric or corrosive environments.

[0005] In manufacturing components and coated parts formed by bonding aluminum with resin, surface treatment of the aluminum is necessary to improve the adhesion between the aluminum and the resin / coating. For example, Patent Document 1 proposes an alkaline alternating current electrolysis method for such surface treatment. In the method of Patent Document 1, an alkaline solution with a liquid temperature of 30–90°C and a pH of 9–13 is used, and alternating current electrolysis is performed for 5–60 seconds, utilizing a waveform where the peak anode voltage at the end of electrolysis is 25–200V and the peak anode voltage at the beginning of electrolysis is 0.1–25V. As a result, Patent Document 1 yields an aluminum material with an oxide film thickness of 50–1000 nm.

[0006] Furthermore, in the case of manufacturing aluminum / thermoplastic resin composite materials that are firmly bonded to aluminum, a chemical treatment method for aluminum, as described in Patent Document 2, is proposed, which utilizes the etching effect of an aqueous solution. Specifically, in the method of Patent Document 2, multiple recesses are formed on the aluminum surface by immersing the aluminum material in an aqueous solution with etching properties under appropriate conditions, or by spraying such solutions onto the aluminum surface. For aluminum materials where a specific recess 1 is defined as a recess with a maximum pore size of 10 μm or more and a maximum depth of 5 μm or more in a cross-section along the length of the maximum pore size, and the total perimeter L (mm) of the specific recesses present on any 1 mm square surface of the roughened surface is 0.10 mm ≤ L ≤ 0.35 mm, a thermoplastic resin is applied as follows: when the tensile breaking strength is set to S (MPa) and the tensile breaking elongation is set to ε (%), the apparent modulus E = S / ε (MPa / %) is 0.0050 ≤ E ≤ 0.0380.

[0007] Furthermore, in the method of Patent Document 3, by forming an anodized coating on an aluminum or aluminum alloy plate with an area of ​​at least 75% of the total area having holes with a diameter of 10 nm or more and a film thickness of 0.1 μm to 1 μm, it is possible to obtain a material in which the thermoplastic resin coating will not peel off from the aluminum or aluminum alloy plate even after a thermoplastic resin coating is formed on the anodized coating and deep drawing or thinning deep drawing is performed under harsh conditions where the drawing ratio becomes 2.5 or more.

[0008] In the aforementioned prior art, in the surface treatment using alternating current electrolysis in Patent Document 1, there is a problem with electrolysis efficiency because about half of the current used to generate the oxide coating is used in the electrolysis current.

[0009] Furthermore, in the method for forming corrosion-resistant aluminum on the surface of aluminum in Patent Document 3, the strength is insufficient when the adhesive tape is used to measure the peel strength of the tape, so further improvement is required.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 2015-25281

[0013] Patent Document 2: Japanese Patent Application Publication No. 2015-102608

[0014] Patent Document 3: Japanese Patent Application Publication No. 11-207860 Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] In order to solve the above-mentioned problems, the inventors have repeatedly conducted research and found that by making the formation and chemical dissolution of the oxide coating occur simultaneously, an oxide with an irregular shape is formed on the surface of the aluminum material, thereby further improving the anchoring effect of the oxide coating and thus exhibiting high adhesion between the aluminum material and other materials.

[0017] Technical means to solve the problem

[0018] That is, the main components of the present invention are as follows.

[0019] [1] A surface-treated aluminum material, comprising an aluminum material and an oxide coating formed on at least a portion of the surface of the aluminum material, wherein, when the perimeter of the voids in the surface of the oxide coating is set as L and the area is set as S, L 2 The roughness of the gap defined by / S×(1 / 4π) is greater than 2.5.

[0020] [2] According to the surface-treated aluminum material described in [1] above, the diameter of the pore is 15 to 65 nm when converted to the equivalent circle diameter.

[0021] [3] The surface-treated aluminum material according to [1] or [2] above, wherein the area occupancy of the voids on the surface of the oxide coating is 10 to 60%.

[0022] [4] The surface-treated aluminum material according to any one of [1] to [3] above, wherein a resin layer is further provided on the surface of the oxide coating.

[0023] [5] The surface-treated aluminum material according to any one of [1] to [4] above, wherein the oxide coating has a barrier-type anodic oxide coating layer formed on at least a portion of the surface of the aluminum material and an aluminum oxide coating layer formed on the barrier-type anodic oxide coating layer, wherein the voids are located on the surface of the aluminum oxide coating layer.

[0024] [6] A method for manufacturing surface-treated aluminum material, which is the method for manufacturing surface-treated aluminum material described in any one of [1] to [5] above, wherein an acidic or alkaline aqueous solution with a liquid temperature of 30 to 90°C is used as the electrolytic solution, and the electrolyte is produced by passing the electrolyte through a current density of 10 A / m. 2 Above and 3000A / m 2 The aluminum material is electrolytically treated in the following manner to form the oxide coating.

[0025] Invention Effects

[0026] It can provide surface-treated aluminum materials and their manufacturing methods that offer excellent adhesion to adhesive films and other materials such as resins. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a surface-treated aluminum material according to one embodiment of the present invention.

[0028] Figure 2 This is a front view of an electrolysis apparatus used in a method for manufacturing surface-treated aluminum materials according to one embodiment of the present invention. Detailed Implementation

[0029] The following is a detailed description of the surface-treated aluminum material of the present invention.

[0030] A. Aluminum

[0031] As an embodiment of the present invention, the aluminum material for surface treatment (e.g., described later) is an aluminum material. Figure 1 In section 2), pure aluminum or aluminum alloys can be used. There are no particular restrictions on the composition of the aluminum alloy, and various alloys, represented by those specified in JIS, can be used. As for the shape of the aluminum material, there are no particular restrictions, and it can be made into flat plates, rods of arbitrary cross-sectional shapes, wires, cylinders, etc. There are no particular restrictions on the manufacturing methods of these shapes, and various methods that can stably form an oxide coating can be preferred.

[0032] B. Oxidation Coating

[0033] Figure 1 This is a schematic diagram of a surface-treated aluminum material according to one embodiment of the present invention. Figure 1 As shown, in one embodiment of the present invention, an oxide coating 1 is formed on at least a portion of the surface of the aluminum material 2 (e.g., at least one of two opposing surfaces in the case of a flat aluminum material). Figure 1 In the example, the oxide coating 1 is composed of an aluminum oxide coating layer 3 and a barrier anodized coating layer 4. The aluminum oxide coating layer 3 is formed on the surface side of the oxide coating and has a void 31, and the barrier anodized coating layer 4 is formed on the aluminum material 2 side.

[0034] B-1. Regarding gaps

[0035] like Figure 1 As shown, small holes, or gaps 31, extending from the surface to the interior are formed on the aluminum oxide coating layer 3. On the surface of the aluminum oxide coating layer 3, the openings of all the existing small holes are defined as gaps 31, relative to the surface area without considering unevenness (which can be calculated by the length × width of the quadrilateral if the surface of the aluminum oxide coating layer 3 is quadrilateral). In this invention, the unevenness of these gaps 31 is 2.5 or more. Here, unevenness is defined by L... 2 / S×(1 / 4π) is defined, where L is the perimeter of the void 31 when viewed from a direction perpendicular to the surface of the oxide coating 1, and S is the area of ​​the void 31. Furthermore, the specific methods for measuring L and S are described later. When the roughness is less than 2.5, the adhesion between the oxide coating 1 and the bonded object decreases. For example, if a resin layer or other bonded object is further coated on the surface of the oxide coating 1, the anchoring effect during the bonding of the oxide coating 1 and the bonded object is insufficient. Therefore, when an adhesive is used to bond the oxide coating 1 and the bonded object, damage occurs at the interface between the outermost surface of the oxide coating 1 and the adhesive. The roughness is preferably 2.5 to 10, more preferably 2.5 to 8, and even more preferably 2.5 to 6. By making the roughness within the above range, the oxide coating 1 and the bonded object disposed thereon can have better adhesion.

[0036] The voids 31 on the surface of the oxide coating 1 have various shapes when viewed from a direction perpendicular to the surface of the oxide coating 1, including circular, elliptical, rectangular, polygonal, and irregular shapes. The diameter of the circle whose circumference is equal to that of a perfect circle is used as the equivalent circle diameter. For example, if the void is circular, its circumference is the same as that of a perfect circle, so the diameter is defined as the equivalent circle diameter. Alternatively, if the void is polygonal, a perfect circle with an equal circumference is used, and the diameter of that perfect circle is defined as the equivalent circle diameter.

[0037] The diameter of the aforementioned gap, converted to an equivalent circle diameter, is preferably 15 nm or more and 65 nm or less, more preferably 25 nm or more and 60 nm or less. When the equivalent circle diameter is 15 nm or more, the anchoring effect when the oxide coating is bonded to the substrate such as resin becomes good, and the adhesion between the oxide coating and the substrate disposed thereon is excellent. On the other hand, if the equivalent circle diameter is 65 nm or less, it is suitable to form a hook structure for achieving the anchoring effect, thus enabling excellent adhesion.

[0038] Furthermore, on the surface of the oxide coating (in one example, an aluminum oxide coating layer 3), the area occupancy rate of the voids is defined as the ratio of the total area of ​​all existing voids 31 to the surface area of ​​the void-containing surface, ignoring any unevenness. Additionally, for example, if the void-containing surface is a quadrilateral, the area occupancy rate of the voids is defined as the ratio of the total area of ​​all existing voids 31 to the surface area calculated by the length × width of the quadrilateral. In this invention, the area occupancy rate of the voids is preferably 10% to 60%, more preferably 15% to 55%. If the area occupancy rate is 10% or more, the anchoring effect when the oxide coating is bonded to the substrate becomes good, resulting in excellent adhesion. If the area occupancy rate is 60% or less, the oxide coating itself is less prone to aggregation and destruction, resulting in excellent adhesion between the oxide coating and the substrate.

[0039] In addition, Figure 1 In this embodiment, the gap 31 does not penetrate the barrier-type anodized coating layer 4 in the depth direction, but the gap 31 may also penetrate the barrier-type anodized coating layer 4. Furthermore, the position of the gap 31 in the depth direction at its leading edge on the opposite side of the surface of the aluminum oxide coating layer 3 is not particularly limited. However, the position of this leading edge is preferably 20% to 100% of the thickness of the oxide coating layer 1 from the surface of the oxide coating layer 1, more preferably 40% to 95%. If it is 20% or more, the anchoring effect when the oxide coating layer is bonded to the substrate becomes good, resulting in excellent adhesion. In one embodiment, the surface-treated aluminum material also has a resin layer on the surface of the oxide coating layer. In this case, as described above, the oxide coating layer and the resin layer can have good adhesion due to the anchoring effect of the oxide coating layer surface. The material constituting the resin layer is not particularly limited; for example, epoxy resin, ABS resin, fluororesin, etc., can be used.

[0040] C. Manufacturing methods for surface-treated aluminum materials

[0041] The following describes a method for manufacturing a surface-treated aluminum material according to one embodiment of the present invention.

[0042] C-1. Electrode

[0043] As a method for manufacturing the surface-treated aluminum material of the present invention, the following method can be cited: the aluminum material to be surface-treated is used as an electrode, and another counter electrode is used to perform electrolytic treatment under specified conditions, thereby forming an oxide coating.

[0044] In one embodiment of the present invention, the shape of the aluminum material to be electrolyzed and the counter electrode are not particularly limited. For example, as a plate-shaped aluminum material, a plate-shaped counter electrode is preferred in order to ensure uniform distance from the counter electrode and stable formation of the oxide coating for electrolytic treatment. Figure 2This is a schematic diagram illustrating the state in which aluminum is used as one electrode, and another electrode is used for electrolytic treatment under specified conditions. For example... Figure 2 As shown, pre-wired counter electrode plates 5 and 6 can be prepared, and an aluminum plate 7 to be surface-treated can be placed between these two counter electrode plates, with the two surfaces of the aluminum plate 7 parallel to the surfaces of the counter electrode plates 5 and 6, respectively. Preferably, the opposing aluminum plates 7 and the surfaces of the counter electrodes are approximately the same size, and the two electrodes are electrolyzed in a static state. Alternatively, if only one surface of the aluminum plate 7 to be surface-treated is required, after disconnecting the counter electrode plate connection switch 10, an insulating film can be pasted onto one side of the aluminum plate to treat only one surface of the aluminum plate 7 (the surface on the left side of the aluminum plate in the figure).

[0045] One of the two electrodes used in the electrolytic process is made of aluminum, which undergoes surface treatment via electrolysis. The counter electrode can be made of known materials such as graphite, aluminum, gold, or titanium, but it must be made of a material that does not degrade the composition or temperature of the electrolyte, has excellent conductivity, and does not itself induce an electrochemical reaction. From this perspective, a graphite electrode is preferred as the counter electrode. This is because graphite electrodes are chemically stable and readily available at low cost.

[0046] C-2. Electrolytic treatment conditions

[0047] Regarding the electrolytic treatment conditions, the electrodes and counter electrodes are made of the aforementioned aluminum material, and an acidic or alkaline aqueous solution with a liquid temperature of 30–90°C is used as the electrolyte, with a current density of 10 A / m. 2 Above and 3000A / m 2 The following method involves electrolytically treating aluminum to form an oxide coating. The current waveform during electrolysis is not limited to AC-DC or AC-DC superposition, but from the viewpoint of electrolysis efficiency, DC current is recommended, preferably with the aluminum material as the anode and a current density of 10 A / m. 2 Above and 3000A / m 2 The following is more preferably 50A / m 2 Above and 2000A / m 2 Hereinafter, 100A / m is further preferred. 2 Above and 1000A / m 2 The optimal value is 100A / m. 2 Above and 300A / m 2 The following describes the current density, defined as the value of the current at which the maximum amount of electricity flows per unit area when AC and AC / DC are applied simultaneously, divided by the reaction area. The recommended current waveform is: [The preferred current density is 10 A / m]. 2 Above and 3000A / m 2The following is more preferably 50A / m 2 Above and 2000A / m 2 Hereinafter, 100A / m is further preferred. 2 Above and 1000A / m 2 The optimal value is 100A / m. 2 Above and 300A / m 2 the following.

[0048] In one embodiment of the present invention, the aqueous solution used as the electrolyte may be an aqueous solution containing the following substances: inorganic acids such as sulfuric acid, phosphoric acid, arsenic acid, and selenic acid; organic acids such as oxalic acid, malonic acid, and etidronic acid; cyclic oxalocarboxylic acids such as squaric acid and rhodizonic acid; borates such as sodium tetraborate; phosphates such as sodium phosphate, sodium hydrogen phosphate, sodium pyrophosphate, potassium pyrophosphate, and sodium metaphosphate; alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; carbonates such as sodium carbonate, sodium bicarbonate, and potassium carbonate; ammonium-containing compounds such as ammonium hydroxide and ammonium borate; or mixtures thereof. Typically, the concentration of these aqueous solutions is 1 × 10⁻⁶. -4 ~12 mol / L, preferably 1×10 -2 ~1 mol / L. It should be noted that surfactants, chelating agents, etc., can also be added to these aqueous solutions to improve the cleanliness of the aluminum surface.

[0049] In one embodiment of the present invention, the temperature of the electrolyte solution used is preferably 30–90°C, more preferably 35–85°C, and even more preferably 60–80°C. If the electrolyte solution temperature is 30°C or higher, the etching force is suitable, thus increasing the area ratio of the voids on the oxide coating surface and ensuring sufficient equivalent circle diameter of the voids. On the other hand, if the electrolyte solution temperature is 90°C or lower, the etching force is suitable, thus preventing the oxide coating from agglomerating and breaking down. Furthermore, the electrolysis time is preferably 5–750 seconds, more preferably 60–600 seconds. An oxide coating can be sufficiently formed within an electrolysis time of 5 seconds or more. As a result, voids with sufficient unevenness can be formed. On the other hand, if the electrolysis time is 750 seconds or lower, excessive oxide coating thickness or oxide coating dissolution will not occur, eliminating the risk of oxide coating agglomeration and breaking down. In addition, the productivity of surface-treated aluminum materials is also improved.

[0050] D. Methods for determining concavity / convexity, equivalent circle diameter, and area occupancy.

[0051] In determining the roughness, equivalent circle diameter, and area ratio of the voids in the porous oxide coating of the present invention, it is suitable to utilize surface observation by field emission scanning electron microscopy (FE-SEM, manufactured by Hitachi High Technology Co., Ltd., SU-8230) and analysis by image analysis software WinRoof 2015 (manufactured by Mitani Corporation, ver. 2.1.0). During scanning electron microscopy (SEM) observation, a conductive layer such as platinum, gold, osmium, or carbon can be coated on the surface of the sample to prevent charging. Specifically, for example, a secondary electron image of a surface-treated aluminum sample taken at an accelerating voltage of 10 kV and an observation magnification of 100,000x is input into the image analysis software. The void portions observed on the surface of the oxide coating are binarized, and image analysis is performed. During image analysis, after binarization with the void portions of the oxide coating as the target area, two closing operations are performed to remove isolated points. Subsequently, select "shape measurement" from the measurement menu as the measurement item, and choose "roughness," "equivalent circle diameter," and "area ratio" to measure the roughness, equivalent circle diameter, and area ratio. Calculate the average values ​​of the measured roughness and equivalent circle diameter, and define them as the roughness and equivalent circle diameter of their respective surfaces. Furthermore, the area occupancy rate of the voids is obtained from the sum of the area ratios; this area occupancy rate represents the ratio of the total void area to the total area ignoring roughness. The roughness, equivalent circle diameter, and area occupancy rate of the voids are as defined above.

[0052] Example

[0053] The present invention will now be described in detail based on embodiments. It should be noted that the present invention is not limited to the examples shown below, and its configuration may be appropriately modified without prejudice to the spirit of the invention.

[0054] (Examples 1-8 and Comparative Examples 1-5)

[0055] As the aluminum material to be electrolytically processed, a high-purity aluminum plate (aluminum material) with a purity of 99.9% or higher and dimensions of 100mm long × 50mm wide × 0.4mm thick is used. This aluminum plate is used as one electrode, and a flat graphite electrode with a length of 200mm × width of 90mm × thickness of 2.5cm is used as the counter electrode. Figure 2 As shown, an aluminum plate electrode 7 is disposed between the counter electrode plates 5 and 6 of the two interconnected and opposing graphite plates, such that both sides of the aluminum plate electrode 7 are parallel to the surfaces of the counter electrode plates 5 and 6 of the opposing graphite plates, for electrolytic treatment of the aluminum plate. Through this electrolytic treatment, an oxide coating consisting of an aluminum oxide coating layer on the surface side and a barrier-type anodic oxide coating layer on the aluminum plate electrode 7, which is opposite to the counter electrode plates 5 and 6 of the two graphite plates, is formed on both sides of the aluminum plate electrode 7.

[0056] The electrolyte solution used for electrolytic treatment is an aqueous solution with oxalic acid as the main component. Furthermore, the electrolyte concentration of this aqueous solution is 0.3 mol / L, as shown in Table 1. An aluminum plate and two pairs of electrodes are arranged in an electrolytic cell containing the electrolyte solution, and direct current electrolysis is performed under the conditions shown in Table 1. In addition, the longitudinal direction of the aluminum plate and the graphite electrode pairs is aligned with the depth direction of the electrolytic cell.

[0057] Table 1

[0058]

[0059] As described above, in Examples 1-8 and Comparative Examples 1-5, the following were performed: Figure 2 When the electrode plate connection switch 10 is in the connected state, an oxide coating is formed on both sides of the aluminum material. After electrolytic treatment, the aluminum material is quickly removed from the electrolytic cell, washed with pure water, dried with a blower, and then naturally dried in the atmosphere at room temperature.

[0060] The following measurements and evaluations were performed on the surface-treated aluminum samples prepared as described above.

[0061] [Determination of the irregularity, equivalent circle diameter, and area occupancy of the porosity when observing the surface of the aluminum oxide coating]

[0062] For the surface-treated aluminum samples prepared as described above, the surface irregularity, equivalent circle diameter, and area occupancy of the aluminum oxide coating were determined by surface observation using FE-SEM and image analysis using WinRoof 2015 (manufactured by Mitani Corporation, ver. 2.1.0). First, secondary electron images of the surface were taken using FE-SEM with an observation field of 2.5 μm × 0.9 μm (accelerating voltage 10 kV), and then image analysis was performed using WinRoof 2015. The results are shown in Table 2. Details of the surface observation and image analysis are as described above.

[0063] Table 2

[0064]

[0065] [Evaluation of the adhesion of the oxide coating]

[0066] On the specimens of the surface-treated aluminum materials prepared as described above, a pressure-sensitive adhesive tape (No. 29) manufactured by Nitto Denko Corporation was pasted. Using a 90° peel tester (manufactured by TESTER Sangyo Co., Ltd., TE-3001-S), the tape was peeled at a speed of 150 mm / min, and thus the tape peel strength was measured. In addition, for the force sensor used for measurement, an LRU-50N manufactured by Nihon Tokushu Sokki Co., Ltd. was used. The measurement results of the tape peel strength are shown in Table 3. When the peel strength is 5 N / cm or more and less than 6.5 N / cm, it is marked as [〇], when it is 6.5 N / cm or more, it is marked as [◎], and in other cases, it is marked as [×]. The cases of 〇 and ◎ are judged as qualified, and the case of × is judged as unqualified.

[0067] Table 3

[0068] Peel strength (N / cm) determination Example 1 5.6 ○ Example 2 5.6 ○ Example 3 7.1 ◎ Example 4 7.9 ◎ Example 5 7.0 ◎ Example 6 6.9 ◎ Example 7 7.1 ◎ Example 8 7.1 ◎ Comparative Example 1 3.6 × Comparative Example 2 2.3 × Comparative Example 3 3.4 × Comparative Example 4 3.6 × Comparative Example 5 3.4 ×

[0069] As shown in Table 3, in Examples 1 to 8, the average value of the unevenness of the voids in the aluminum oxide coating layer is 2.5 or more. Therefore, the adhesion between the oxide coating and the adhesive film is good, and the adhesiveness is qualified.

[0070] As shown in Table 3, in contrast, in Comparative Examples 1 to 5, the surface-treated aluminum materials having the oxide coating structure according to the present invention were not obtained. As a result, the adhesion between the oxide coating and the adhesive film was insufficient, and the adhesiveness was unqualified.

[0071] Specifically, in Comparative Example 1, since the temperature of the electrolytic solution in the electrolytic treatment was too low, the etching power became weak, the area occupancy rate of the voids in the aluminum oxide coating layer was insufficient, and the unevenness was also low. Therefore, the adhesiveness was unqualified.

[0072] In Comparative Example 2, in the electrolytic treatment, a high-temperature solution was used for electrolysis at a high current density for a long time. Therefore, over-etching occurred, resulting in the cohesive failure of the aluminum oxide coating layer itself. As a result, the adhesiveness was unqualified.

[0073] In Comparative Example 3, the temperature of the electrolytic solution in the electrolytic treatment was low, and the current density was also low. Therefore, the etching power became weak, the area occupancy rate of the voids in the aluminum oxide coating layer was insufficient, and the unevenness was also low. Therefore, the adhesiveness was unqualified.

[0074] In Comparative Example 4, similarly to Comparative Example 3, the temperature of the electrolytic solution in the electrolytic treatment was low. Therefore, the etching power became weak, the area occupancy rate of the voids in the aluminum oxide coating layer was insufficient, and the unevenness was also low. Therefore, the adhesiveness was unqualified.

[0075] In Comparative Example 5, in the electrolytic treatment, the electrolysis time was short relative to the current density. Therefore, the etching of the voids was insufficient, and a large number of fine pores were generated. As a result, the unevenness was insufficient. As a result, the adhesiveness was unqualified.

[0076] Industrial availability

[0077] According to the present invention, surface-treated aluminum materials with excellent adhesion to bonded bodies such as adhesive tapes or resins can be obtained. Therefore, the surface-treated aluminum materials of the present invention are suitable for aluminum-resin bonded components and resin-coated aluminum materials requiring resin adhesion to aluminum.

[0078] Symbol Explanation

[0079] 1. Oxidation coating

[0080] 2 Aluminum materials

[0081] 3 Aluminum oxide coating layer

[0082] 4-Barrier Anodized Coating

[0083] 5 and 6 pairs of electrode plates

[0084] 7 Aluminum Plate

[0085] 31 gaps

Claims

1. A surface-treated aluminum material, comprising an aluminum material and an oxide coating formed on at least a portion of the surface of the aluminum material. When the perimeter of the pores on the surface of the oxide coating is set as L and the area as S, L 2 The concavity / convexity of the gap defined by / S×(1 / 4π) is 2.5~10. The diameter of the gap, converted to the equivalent circle diameter, is 15nm to 65nm. The porosity of the surface area of ​​the oxide coating is 10% to 60%. The gaps are small pores that extend from the surface of the oxide coating inward.

2. The surface-treated aluminum material according to claim 1, wherein, A resin layer is also present on the surface of the oxide coating.

3. The surface-treated aluminum material according to claim 1 or 2, wherein, The oxide coating has a barrier anodized coating layer formed on at least a portion of the surface of the aluminum material and an aluminum oxide coating layer formed on the barrier anodized coating layer. The gap is located on the surface of the aluminum oxide coating layer.

Images