Aluminum material with surface treatment film, method for producing the same, joined body of aluminum material and resin molding using the same, and method for producing the same

Abstract

To provide a joined body of an aluminum material and a resin molding, having excellent bond strength with the resin molding and excellent corrosion resistance, and also to provide an aluminum material with a surface treatment film capable of providing the joined body.SOLUTION: The problem is solved by a method for producing an aluminum material with a surface treatment film, the method including: a first step of bringing an aluminum material into contact with a surface treatment agent containing a lithium ion source and an alkali source; a second step of bringing an acidic aqueous solution containing an inorganic acid into contact with the surface of the aluminum material that has been in contact with the surface treatment agent; and a third step of performing an anodic oxidation treatment on the aluminum material that has been in contact with the acidic aqueous solution to form an anodic oxide film having irregularities on the surface.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an aluminum material having a surface treatment film excellent in corrosion resistance and resin bonding property, a method for producing the same, a bonded body in which the aluminum material and a resin molded body are bonded, and a method for producing the same.

Background Art

[0002] In recent years, the demand for bonded products obtained by bonding an aluminum alloy base material and a resin has been increasing. Examples of such bonded products include bonded products in which an aluminum alloy molded product and another member are bonded via a resin adhesive, and bonded products in which an aluminum alloy molded product and a resin member are directly bonded. However, such bonded products obtained by bonding different materials may have insufficient bonding strength.

[0003] Non-Patent Document 1 describes a method of anodizing an aluminum alloy base material using an aqueous phosphoric acid solution as an electrolytic solution as a method for improving the bonding strength between an aluminum alloy molded product and a resin. However, it is difficult to stably produce a bonded product having high bonding strength by this method, and there has been a problem in industrial use, such as a decrease in adhesive strength (short lifetime) due to changes over time after anodizing.

[0004] On the other hand, Patent Document 1 describes that after forming a first oxide film by anodizing an aluminum alloy base material using an electrolytic solution containing 0.5 to 7 mol / L of phosphoric acid and having a sulfuric acid content of less than 0.5 mol / L, and then forming a second oxide film by anodizing the base material using an electrolytic solution containing 0.5 to 5 mol / L of sulfuric acid, the bonding strength and corrosion resistance are improved by bonding a resin to the surface of the oxide film. However, the bonding strength and corrosion resistance of such bonded products may still be insufficient.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Non-Patent Literature

[0006]

Non-Patent Literature 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a bonded body of an aluminum material and a resin molded body, which has excellent bonding strength and corrosion resistance with the resin molded body, and an aluminum material having a surface treatment film that can provide the bonded body.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by an aluminum material having a surface treatment film produced by a manufacturing method including a first step of using a surface treatment agent containing a lithium ion source and an alkali source, a second step of using an acidic aqueous solution containing an inorganic acid, and a third step of performing an anodizing treatment, and has completed the present invention. That is, the gist of the present invention is as follows.

[0009] [1] A method for manufacturing an aluminum material having a surface treatment film, the method including a first step of bringing an aluminum material into contact with a surface treatment agent containing a lithium ion source and an alkali source, a second step of bringing an acidic aqueous solution containing an inorganic acid into contact with the surface of the aluminum material that has been brought into contact with the surface treatment agent, and a third step of performing an anodizing treatment on the aluminum material that has been brought into contact with the acidic aqueous solution to form an anodic oxide film having unevenness on the surface. [2] The method for manufacturing an aluminum material having a surface treatment film according to [1], wherein the surface of the aluminum material satisfies the following requirements. (1) The thickness of the anodic oxide film is more than 0.1 μm. (2) The average value a of the distances between adjacent convex portions of the unevenness is 50 to 1000 nm, and the aspect ratio b / a with the average value b of the recess depth is 2 or more and 50 or less. (3) It has fine pores with a diameter of 5 to 30 nm. A method for manufacturing a bonded body of an aluminum material and a resin molded body, the method including a step of inserting a resin composition into the unevenness on the surface of an aluminum material having a surface treatment film obtained by the manufacturing method according to [3][1] or [2]. A bonded body of an aluminum material and a resin molded body obtained by the manufacturing method according to [4][3]. [5] An aluminum material having a surface treatment film, wherein the surface treatment film is an anodic oxidation film, An aluminum material having a surface treatment film, wherein the surface of the aluminum material has unevenness and satisfies the following requirements. (1) The thickness of the anodic oxidation film is more than 0.1 μm. (2) The average value a of the distances between adjacent convex portions of the unevenness is 50 to 1000 nm, and the aspect ratio b / a with the average value b of the recess depth is 2 or more and 50 or less. (3) It has fine pores with a diameter of 5 to 30 nm. [6] A bonded body of an aluminum material having the surface treatment film according to [5] and a resin molded body.

Advantages of the Invention

[0010] According to the present invention, when bonded to a resin molded body, a high bonding strength can be stably obtained, and an aluminum material having a surface treatment film excellent in corrosion resistance and a bonded body of the aluminum material and a resin molded body can be provided.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in detail. One form of the present invention is an aluminum material having a surface treatment film, and the surface treatment film is an anodic oxidation film.

[0013] <Aluminum material> The aluminum material is not particularly limited as long as at least all or part of the surface is a substrate made of aluminum or an aluminum alloy material. The aluminum material is not particularly limited and includes rolled materials, extruded materials, cast materials, and die-cast materials. The aluminum material may be used alone or in combination of two or more.

[0014] The aluminum or aluminum alloy is not particularly limited, and any aluminum material used industrially can be applied. The aluminum material typically refers to a material containing 60% or more of aluminum. Examples of alloy components other than aluminum include magnesium, silicon, titanium, chromium, manganese, iron, nickel, copper, and zinc. Specifically, for example, A1050, A2014, A2024, A3003, A5052, A5N01, A6061, A6063, A7075, AC4A, ADC12, etc. specified in JIS H 4000, JIS H 5302, and JIS H 5202 can be mentioned.

[0015] The shape of the aluminum material is not particularly limited. For example, it may be a plate, rod, strip, tube, wire, fiber, foil, or lump, or it may be a structure combining these. However, it is preferably in a shape that can be joined to a resin. Note that the aluminum material includes all intermediate products and finished products within the scope. It may be a base material containing the aluminum material and other materials. Of course, it may also be composed only of the aluminum material. Materials other than the aluminum material include, for example, metals other than aluminum, resins, rubbers, woods, ceramics, composite materials, etc., but are not limited thereto. Also, the joining method is not particularly limited. When joining to a resin molded body, the shape of the surface of the joining part of the aluminum material includes, but is not particularly limited to, a flat surface or a curved surface, etc.

[0016] The aluminum material may be subjected to plastic processing, cutting processing, blasting processing, polishing processing, electrical discharge machining, drilling processing, heat treatment (such as aging hardening treatment, solution treatment, etc.). Also, surface treatment (such as chemical conversion treatment, plating treatment, etc.) may be performed, but it is preferable to remove these film components by polishing or chemical treatment, etc. before forming the unevenness described below.

[0017] The aluminum material has an anodic oxidation film on its surface. The anodic oxidation film is formed by the third step described later.

[0018] In this form, the surface of the aluminum material has unevenness and has the following characteristics (1) to (3). (1) The thickness of the anodic oxide film is more than 0.1 μm. (2) The average value a of the distances between adjacent convex portions of the unevenness is 50 to 1000 nm, and the aspect ratio b / a with the average value b of the recess depth is 2 or more and 50 or less. (3) It has micropores with a diameter of 5 to 30 nm. Thus, when an aluminum material having an anodic oxide film with unevenness on the surface is used for manufacturing a bonded body of the aluminum material and a resin molded body, a high bonding strength between the aluminum material and the resin molded body can be stably obtained, and moreover, a bonded body of the aluminum material - resin molded body excellent in corrosion resistance can be formed.

[0019] The thickness of the anodic oxide film is more than 0.1 μm, preferably 0.5 μm or more, and more preferably 1.0 μm or more. By having the anodic oxide film with the above thickness, corrosion resistance can be imparted to the surface of the aluminum material. The upper limit is not particularly limited, but is usually 100 μm or less, may be 50 μm or less, or may be 10 μm or less.

[0020] Next, the method for measuring the uneven shape and micropores on the surface of the aluminum material will be described below.

[0021] (Aspect ratio) The aspect ratio according to this embodiment is calculated by the ratio b / a of the average value a of the distances between adjacent convex portions of the unevenness and the average value b of the depths of the concave portions. That the aspect ratio is 2 or more means that there is unevenness having an average depth of the concave portion where b is 2 times or more of a. The average value of the distances between adjacent convex portions of the unevenness can be measured from a photograph taken with an electron microscope of the surface of the aluminum material having the anodic oxide film. As shown in FIG. 1, circular or elliptical holes are observed on the surface of the aluminum material, which constitute the unevenness of the surface. That is, the hole portion becomes the concave portion of the surface unevenness. The holes are not only formed to extend in a direction perpendicular to the surface, but may also be formed in an oblique direction. Further, the holes may be formed to meander in the depth direction. The average value of the distances between adjacent convex portions of the unevenness is the average value of the diameters (a in FIG. 1) or minor diameters (b in FIG. 1) of the circular or elliptical openings formed on the surface, and is the average value of 20 arbitrary distances between convex portions observed with an electron microscope. In addition, there may be a portion where the concave portions overlap, and in that case, it is preferable to measure a portion where the concave portions do not overlap. In order to obtain the diameter and minor diameter of the opening, it is preferable to set the magnification to 10,000 times or more and 50,000 times or less in the electron microscope observation.

[0022] When the average value a of the distances between adjacent convex portions of the unevenness is measured for a large number of unevenness, when the substrate is cut in a direction perpendicular to the actual surface, the average value a of the distances between adjacent convex portions of the unevenness can also be measured from a photograph taken with an electron microscope of the cross-sectional structure appearing at the cut surface. In that case, the average value of the distances between adjacent convex portions of the unevenness is the average value of c in FIG. 2, and the average value of 10 arbitrary distances between convex portions is taken as the average value of the distances between adjacent convex portions of the unevenness. In order to obtain the distance between convex portions, it is preferable to set the magnification to 10,000 times or more and 50,000 times or less in the electron microscope observation. It is more preferable to obtain the average value of the distances between adjacent convex portions of the unevenness from a photograph taken with an electron microscope of the surface of the aluminum material having the anodic oxide film.

[0023] The average value b of the depth of the recesses is measured from a photograph taken by electron microscope observation of the cross-sectional structure appearing at the cut surface when the aluminum material having the anodic oxide film is cut in a direction perpendicular to the actual surface. In order to determine the depth of the unevenness, it is preferable that the magnification in the electron microscope observation is 10,000 times or more and 50,000 times or less. Since the holes are formed not only extending in a direction perpendicular to the surface but also in an oblique direction, there may be cases where recesses are intermittently observed in the depth direction from the outermost surface as shown in FIG. 2 in the cross-sectional observation photograph. The average value b of the depth of the recesses is the average value of the length (d in FIG. 2) between the uppermost part and the deepest part of the convex portions in the formed unevenness and the length (e in FIG. 2) between the outermost surface and the deepest part, and the average value of the top 10 in terms of the length of the depth of the recesses is taken as the average value of the depth of the recesses.

[0024] From the viewpoint of further improving the bonding strength between the aluminum material and the resin, the range of the average value (a) of the distance between adjacent convex portions of the unevenness of the aluminum material is preferably 50 nm or more and 1000 nm or less, more preferably 60 nm or more and 800 nm or less, and still more preferably 70 nm or more and 600 nm or less.

[0025] From the viewpoint of further improving the bonding strength between the aluminum material and the resin, the range of the average value b of the depth of the recesses is preferably 0.1 μm or more and 10 μm or less, more preferably 0.2 μm or more and 9 μm or less, and still more preferably 0.3 μm or more and 8 μm or less.

[0026] The aspect ratio defined above is 2 or more, preferably 3 or more, and still more preferably 4 or more from the viewpoint of further improving the bonding strength between the aluminum material and the resin. Also, when the aspect ratio exceeds 50, the strength of the aluminum material itself may decrease.

[0027] The unevenness is observed at any 10 locations on the surface and cross-section of the aluminum material, and confirmed at one or more locations. It suffices if it can be recognized. More specifically, the number of unevennesses having the aspect ratio on the surface of the aluminum material is preferably one or more, and more preferably two or more per 1 μm of the surface area of the aluminum material. The unevennesses do not necessarily have to be present on the entire surface of the aluminum material, and it suffices if at least the portion that joins with the resin described later has them. Note that the number of unevennesses per 1 μm of the surface area of the aluminum material is preferably one or more and 200 or less. 2 In addition to the unevennesses described above, the aluminum material having a surface treatment film has fine pores with an average diameter of 5 to 30 nm in diameter observed by surface observation using an electron microscope. The fine pores are pores oriented in the thickness direction of the surface treatment film and can be measured from a photograph of the surface of the aluminum material taken with an electron microscope. The fine pores may be located in any of the convex portions, concave portions, and side surfaces of the unevennesses described above. In order to obtain the average diameter of the fine pores, it is preferable to set the magnification to 200,000 times or more in the electron microscope. 2 It suffices if it can be recognized. More specifically, the number of unevennesses having the aspect ratio on the surface of the aluminum material is preferably one or more, and more preferably two or more per 1 μm of the surface area of the aluminum material. The unevennesses do not necessarily have to be present on the entire surface of the aluminum material, and it suffices if at least the portion that joins with the resin described later has them. Note that the number of unevennesses per 1 μm of the surface area of the aluminum material is preferably one or more and 200 or less.

[0028] (Fine pores) In addition to the unevennesses described above, the aluminum material having a surface treatment film has fine pores with an average diameter of 5 to 30 nm in diameter observed by surface observation using an electron microscope. The fine pores are pores oriented in the thickness direction of the surface treatment film and can be measured from a photograph of the surface of the aluminum material taken with an electron microscope. The fine pores may be located in any of the convex portions, concave portions, and side surfaces of the unevennesses described above. In order to obtain the average diameter of the fine pores, it is preferable to set the magnification to 200,000 times or more in the electron microscope.

[0029] The average value of the diameter of the fine pores is the average value of the diameter or the minor axis of the circular or elliptical opening formed on the surface, and the average value of any 20 locations observed with an electron microscope is taken as the average value of the diameter of the fine pores.

[0030] It suffices if one or more fine pores can be confirmed by observing any 10 locations on the surface of the aluminum material. More specifically, the number of fine pores on the surface of the aluminum material having a surface treatment film is preferably five or more and preferably 30 or less per 0.1 μm of the surface area of the aluminum material. The fine pores do not necessarily have to be present on the entire surface of the aluminum material, and it suffices if at least the portion that joins with the resin described later has them. 2 It suffices if one or more fine pores can be confirmed by observing any 10 locations on the surface of the aluminum material. More specifically, the number of fine pores on the surface of the aluminum material having a surface treatment film is preferably five or more and preferably 30 or less per 0.1 μm of the surface area of the aluminum material. The fine pores do not necessarily have to be present on the entire surface of the aluminum material, and it suffices if at least the portion that joins with the resin described later has them.

[0031] <Method for manufacturing a surface-treated aluminum material> Next, a method for manufacturing a surface-treated aluminum material having an anodic oxidation film on the surface will be described. As a method for manufacturing a surface-treated aluminum material having an anodic oxide film and further having irregularities on the surface, a method having the following first to third steps can be mentioned. First step: A step of bringing an aluminum material into contact with a surface treatment agent containing a lithium ion source and an alkali source. Second step: A step of bringing an acidic aqueous solution containing an inorganic acid into contact with the surface of the aluminum material that has been brought into contact with the surface treatment agent. Third step: A step of performing anodic oxidation treatment on the aluminum material that has been brought into contact with the acidic aqueous solution to form an anodic oxide film having irregularities on the surface.

[0032] (First step) In the first step, a lithium-containing film containing lithium element is formed by bringing a surface treatment agent containing a lithium ion source and an alkali source into contact with the surface of the aluminum material. At that time, it involves a dissolution reaction of the passive film including the oxide film on the surface of the aluminum material. The film containing lithium element can be formed using a known method. For example, but not limited to, boehmite treatment or chemical conversion treatment can be mentioned. Here, the lithium-containing film containing lithium element includes a hydroxide film, an oxide film, a hydrated oxide film, etc. containing a metal derived from the aluminum material. As the treatment method, for example, the methods described in JP-A-48-89138, JP-A-53-11841, etc. can be used.

[0033] (Lithium ion source) As the lithium ion source, an appropriate one or more can be selected from lithium hydroxide, chloride, carbonate, bicarbonate, nitrate, nitrite, sulfate, persulfate, bromide, bromate, etc. The surface treatment agent used in the first step preferably contains lithium ions at 0.001 mol / L or more and 5.00 mol / L or less, more preferably 0.10 mol / L or more and 4.00 mol / L or less, and even more preferably 0.50 mol / L or more and 3.50 mol / L or less. Also, the lithium ion concentration may exceed the saturation solubility.

[0034] (Alkali source) Examples of the alkali source include hydroxides of alkali metals or alkaline earth metals, and water-soluble amine compounds. The alkali metal or alkaline earth metal is not particularly limited, and an appropriate one or more can be selected from lithium, sodium, magnesium, potassium, calcium, etc.

[0035] When the surface treatment agent used in the first step uses a hydroxide of an alkali metal or alkaline earth metal as the alkali source, the molar concentration of the alkali source usually includes 0.001 mol / L or more and 5.00 mol / L or less, more preferably 0.005 mol / L or more and 4.00 mol / L or less, and still more preferably 0.01 mol / L or more and 3.00 mol / L or less. Further, the concentration of the hydroxide of the alkali metal and alkaline earth metal may exceed the saturation solubility.

[0036] As the alkali source, as the water-soluble amine compound, a primary amine bonded with an alkyl group having 1 to 12 carbon atoms, a secondary amine bonded with an alkyl group having 1 to 12 carbon atoms, a tertiary amine bonded with an alkyl group having 1 to 12 carbon atoms, and a primary amine bonded with a hydroxyalkyl group having 1 to 12 carbon atoms, a secondary amine bonded with a hydroxyalkyl group having 1 to 12 carbon atoms, and a tertiary amine bonded with a hydroxyalkyl group having 1 to 12 carbon atoms can all be used. In addition to these water-soluble amines, aromatic amines in which a part or all of the alkyl group or hydroxyalkyl group is substituted with a phenol group are also used. Further, at least one methylene in the alkyl group having 1 to 12 carbon atoms may be substituted with -NH-. Specific water-soluble amine compounds can be appropriately selected from monoethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, dimethylaminoethanol, triethylenetetraamine, hexamethylenetetraamine, ethylenediamine, ammonia, etc., one or more.

[0037] When a water-soluble amine compound is used as the alkali source, the molar concentration of the alkali source is preferably 0.001 mol / L or more and 1.00 mol / L or less, more preferably 0. It can be mentioned that it is 05 mol / L or more and 0.90 mol / L or less, and more preferably, it contains 0.01 mol / L or more and 0.80 mol / L or less.

[0038] As the surface treatment agent in the first step, among the hydroxides of alkali metals or alkaline earth metals and water-soluble amine compounds, one component can be used alone, or several components can be used in combination.

[0039] It is desirable that the surface treatment agent in the first step does not contain zinc ions and silicate ions. When zinc ions are present, a zinc replacement film may be formed on the surface of the aluminum material, and the desired unevenness may not be obtained. Also, when silicate ions are present, a film containing silicon may be formed on the surface of the aluminum material, and the desired unevenness may not be obtained. Furthermore, it is desirable that it does not contain transition metal ions such as copper, iron, nickel, and tin. Note that sodium, potassium, magnesium, calcium, etc. supplied from the hydroxides of alkali metals and alkaline earth metals and their salts may be contained in the formed surface treatment film.

[0040] The surface treatment agent in the first step can be easily prepared by dissolving a lithium ion source and an alkali source in ion-exchanged water, industrial water, tap water, etc. In the surface treatment agent, elements such as aluminum, magnesium, silicon, titanium, chromium, manganese, iron, nickel, copper, and zinc derived from the aluminum material and water may be present.

[0041] An organic solvent, a surfactant, and a chelating agent may be added to the surface treatment agent in the first step. When adding these other components, the total content thereof is preferably 50.0 mass % or less based on the total amount of the surface treatment agent.

[0042] By bringing the aluminum material into contact with the surface treatment agent in the first step, a film containing lithium element can be formed on the surface of the aluminum material. The adhesion amount of the film is not particularly limited, and the film may be a continuous film or a discontinuous film.

[0043] Examples of the method of bringing the surface treatment agent in the first step into contact with the aluminum material include immersion and spraying treatment methods. By bringing the surface treatment agent into contact with the aluminum material, it is possible to form a film containing lithium element on the aluminum material, and it is also possible to use electrolytic treatment in combination.

[0044] The liquid temperature of the surface treatment agent during contact is preferably 20.0°C to 100.0°C. The pH is preferably adjusted to 8.0 to 13.0, more preferably 8.5 to 12.5. The contact time is preferably 5 seconds to 1800 seconds, more preferably 10 seconds to 1200 seconds. After the first step, a water washing step and a drying step may be performed as necessary.

[0045] (Second step) The acidic aqueous solution used in the second step contains an inorganic acid. As the inorganic acid, one or more suitable ones can be selected from sulfuric acid, nitric acid, hydrochloric acid, amidosulfuric acid, etc., but it is not limited thereto. Further, the acidic aqueous solution may contain organic acids, inorganic acid salts, organic acid salts, etc., but it is desirable that it does not contain transition metals. As the organic acid, one or more suitable acids can be selected from formic acid, citric acid, oxalic acid, malic acid, succinic acid, malonic acid, ethylenediaminetetraacetic acid, gluconic acid, etc., but are not limited thereto. Further, as the inorganic acid salt and the organic acid salt, one or more suitable salts can be selected from alkali metal salts, alkaline earth metal salts, and ammonium salts of the inorganic acid and the organic acid, but are not limited thereto. The acidic aqueous solution can contain one or more of the above inorganic acids, organic acids, or salts thereof. Although the unevenness may be formed even with an acidic aqueous solution of any one of the organic acid, inorganic acid salt, or organic acid salt alone, an acidic aqueous solution of an inorganic acid alone is preferred from an industrial perspective.

[0046] The total content of the components containing the inorganic acid in the acidic aqueous solution is preferably 0.1% by mass to 70.0% by mass, more preferably 0.5% by mass to 50.0% by mass, and even more preferably 1.0% by mass to 45.0% by mass with respect to the total amount of the acidic aqueous solution.

[0047] A surfactant, a chelating agent, or the like may be added to the acidic aqueous solution in the second step. When adding these other components, the total content is preferably 10.0% by mass or less with respect to the total amount of the acidic aqueous solution.

[0048] The acidic aqueous solution in the second step can be easily prepared by dissolving the above components in ion-exchanged water, industrial water, tap water, etc. In the acidic aqueous solution, elements such as aluminum, magnesium, silicon, titanium, chromium, manganese, iron, nickel, copper, and zinc derived from the aluminum material and water may be present. Further, components associated with the dissolution of the film containing lithium element formed in the first step may be mixed in.

[0049] Examples of the method of bringing the acidic aqueous solution containing the inorganic acid in the second step into contact with the aluminum material include immersion and spraying treatment methods. It is also possible to use electrolysis treatment in combination.

[0050] The temperature of the acidic aqueous solution at the time of contact is preferably 10.0° C. to 80.0° C. The pH may be any acidic value, and is preferably adjusted to, for example, pH 6.0 or less, and more preferably pH 3.0 or less. is more preferable, and even more preferable is a pH of 1 or less. The contact time is preferably 1 to 1800 seconds, more preferably 5 to 1200 seconds, and even more preferably 10 to 900 seconds. After the second step, a water-washing step and a drying step are usually carried out. In the water-washing step, ultrasonic waves may be used in combination. In the drying step, natural drying may be performed, or a dryer, an air blower, an oven, or the like may be used.

[0051] After the second step, drying may be performed before the third step, or the third step may be performed without drying. When an acidic aqueous solution containing an inorganic acid is used in the third step, the second step can be omitted, but from the viewpoint of controlling the composition of the electrolytic solution in the third step, it is preferable to perform the second step between the first step and the third step.

[0052] (Third step) For the anodizing treatment in the third step, a known anodizing method can be appropriately adopted. For example, the aluminum material surface can be anodized by electrolysis in an acidic or alkaline solution using an aluminum material as the anode and an insoluble electrode as the cathode, to form an aluminum oxide film (anodic oxide film).

[0053] The electrolysis method used in the anodization treatment is not particularly limited, and for example, electrolysis methods such as a cyclic method, a constant current method, a constant potential method, a pulse constant potential method, and a pulse constant current method can be used.

[0054] The cathode used in the anodizing treatment is not particularly limited, and may be made of, for example, platinum, lead, stainless steel, carbon, aluminum, or other materials.

[0055] In the anodizing treatment, an acidic solution or an alkaline solution can be used as the electrolytic solution. Examples of the acidic solution include solutions such as chromic acid, oxalic acid, and sulfuric acid, and one or more of these can be mixed and used. However, from the perspective of the corrosion resistance of the film, it is desirable not to use a phosphoric acid solution. Examples of the mixed acid bath include, in addition to the mixed system of the acidic solutions described above, sulfosalicylic acid-sulfuric acid system, sulfosalicylic acid-maleic acid system, and the like. Examples of the alkaline solution include ammonia-fluoride system, alkali-peroxide system, and sodium phosphate system. Among such electrolytic solutions, acidic solutions such as oxalic acid and sulfuric acid solution are preferred.

[0056] As the concentration of the acidic solution, for example, when an aqueous sulfuric acid solution is used as the acidic solution, it is preferably 0.1 mass% to 50.0 mass%, more preferably 1.0 mass% to 40.0 mass%, and even more preferably 5.0 mass% to 30.0 mass%. When an aqueous oxalic acid solution is used, it is preferably 0.1 mass% to 40.0 mass%, more preferably 0.5 mass% to 30.0 mass%, and even more preferably 1.0 mass% to 20.0 mass%. Also, the temperature of the acidic solution is preferably -10 to 80°C, more preferably -10 to 60°C. By performing the anodizing treatment at this temperature, an anodic oxide film having fine pores of 5 to 30 nm is formed. As a result, the surface area of the aluminum material surface is further enlarged, so that the contact with the resin becomes easy, and the resin in contact with the surface-treated aluminum material surface is embedded (bites into) the aluminum material surface, making it possible to simply and firmly bond the aluminum material and the resin material. The electrolytic solution in the third step can be easily prepared by diluting the above components with ion-exchanged water, industrial water, tap water, etc. In the electrolytic solution, elements such as aluminum, magnesium, silicon, titanium, chromium, manganese, iron, nickel, copper, and zinc derived from the aluminum material and water may be present. Also, the components used in the first and second steps may be mixed in. Additives such as surfactants, chelating agents, and organic compounds may be added to the electrolytic solution for the third process. When adding these other components, the total content thereof is preferably 10.0% by mass or less based on the total amount of the electrolytic solution.

[0057] The current density of the constant current electrolysis used in the anodizing treatment is not particularly limited. For example, it is preferably 0.01 to 10 A / dm 2 preferably 0.05 to 5 A / dm 2 preferably 0.1 to 2.5 A / dm 2 is even more preferably. If the current density of the electrolysis is less than the lower limit, the formation rate of the anodic oxide film tends to be extremely slow. On the other hand, if it exceeds the upper limit, the dissolution of the anodic oxide film becomes intense, and the uneven shape tends to be smoothed. The electrolysis time in the anodizing treatment is preferably 30 seconds to 100 minutes, more preferably 60 seconds to 60 minutes. The current density and the electrolysis time can be appropriately adjusted according to the required thickness of the anodic oxide film.

[0058] The anodizing treatment may be performed multiple times, or may be performed multiple times using different electrolytic solutions. From the viewpoint of improving corrosion resistance, the thickness of the anodic oxide film is more than 0.1 μm, may be 0.3 μm or more, preferably 0.5 μm or more, preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more. Also, the thickness of the anodic oxide film is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less. If the thickness of the anodic oxide film is 0.1 μm or less, sufficient corrosion resistance cannot be obtained, and if it exceeds 100 μm, cracks are likely to occur, and the corrosion resistance may decrease. The anodic oxide film in the third step is formed along the surface unevenness formed by the first and second steps. Therefore, the anodic oxide film is formed from any of the convex portions, concave portions, and side faces of the unevenness. The thickness of the anodic oxide film can be measured from a photograph obtained by observing the cross-sectional structure that appears at the cut surface when the aluminum material having the anodic oxide film is cut in a direction perpendicular to the actual surface, using an electron microscope, an optical microscope, or the like. In order to determine the thickness of the anodic oxide film, it is preferable that the magnification in the microscopic observation is 100 times or more and 50,000 times or less. The thickness of the anodic oxide film is the average value of the length between the uppermost part of the convex portion and the deepest part of the anodic oxide film in the formed unevenness, and is the average value of any 10 places observed with a microscope. The thickness of the anodic oxide film may be thinner than the average value b of the depth of the concave portion.

[0059] After the third step, usually, a water washing step and a drying step are performed. In the water washing step, ultrasonic waves may be used in combination. In the drying step, natural drying may be used, or a dryer, an air blower, an oven, or the like may be used.

[0060] In the manufacturing method according to the embodiment of the present invention, the entire surface of the aluminum material may be processed, or a part thereof may be processed. In order to obtain excellent bonding strength with the resin, only the portion to be bonded to the resin needs to be processed.

[0061] In the manufacturing method of the surface-treated aluminum material according to the embodiment of the present invention, other steps may exist. Examples of other steps include a step of processing the surface of the aluminum material and a step of cleaning it before the first step. Each step may be repeated if necessary. Hereinafter, each step will be described in detail.

[0062] (Surface processing step) Before the first step, the aluminum material may be subjected to a mechanical roughening treatment such as shot blasting, sand blasting, or grinding, a physical roughening treatment such as laser processing or plasma processing, or a roughening treatment in advance by a chemical method. The uneven shape formed after these processes is not limited.

[0063] (Surface cleaning process) Before the first step, in order to clean the surface of the aluminum material, a pretreatment consisting of degreasing treatment, acid treatment with an acid aqueous solution, and / or alkali treatment with an alkali solution may be performed. The method of degreasing treatment is not particularly limited. For example, a solvent-based, water-based, or emulsion-based degreasing agent can be used, and it may contain an alkali salt, a surfactant, etc. As the method of pretreatment by acid treatment, inorganic acids such as sulfuric acid, nitric acid, phosphoric acid, and hydrofluoric acid, organic acids such as citric acid and gluconic acid, or those prepared by mixing these can be used. Also, as the method of pretreatment by alkali treatment, those prepared from alkali reagents such as sodium hydroxide and potassium hydroxide, or those prepared by mixing these can be used.

[0064] (Post-treatment process) After the implementation of the third step, post-treatment processes such as sealing treatment (boiling water sealing, pressurized steam sealing, metal salt sealing treatment, sealing with the addition of triethanolamine to boiling water, etc.), acid treatment, coloring, dyeing, painting, electrocoating, plating, etc. may be performed on the surface of the aluminum material having the surface treatment film. Also, after forming a joined body with the resin molded body described later, the above-mentioned sealing treatment, acid treatment, coloring, dyeing, painting, electrocoating, plating, etc. may be performed.

[0065] (Other treatment processes) In addition to the above-mentioned steps, other steps may be appropriately performed as necessary. For example, the water washing step may be performed before and after all steps (such as the surface processing step, surface cleaning step, pore formation step, post-treatment step, etc.). Also, a drying step may be appropriately performed after each water washing step.

[0066] ><Method for manufacturing a joined body of an aluminum material and a resin molded body> The aluminum material having the surface treatment film can be made into a joined body by joining with a resin molded body. The joined body of the surface-treated aluminum material and the resin molded body contains the resin molded body (cured product) in the unevenness on the surface of the aluminum material having the surface treatment film.

[0067] The resin molded body may be any resin, such as a thermoplastic resin, a thermosetting resin, a thermoplastic elastomer, a cured resin paint to form a coating film, or a cured adhesive.

[0068] The method for manufacturing the joined body includes a step of inserting a resin composition into the unevenness on the surface of an aluminum material having a surface treatment film. After the step of inserting the resin composition into the unevenness, the resin composition is cured by cooling, leaving it standing, or heating to form a joined body. The joined body may be composed of only an aluminum material and a resin molded body, or may include, in addition to the aluminum material and the resin molded body, a mating material that contacts the resin molded body. The mating material may be any material including not only resin materials but also metals, rubbers, woods, ceramics, and composite materials. Further, the shape of the mating material is not particularly limited, and it may be a plate, rod, strip, tube, wire, film, or the like.

[0069] As a specific method for manufacturing the joined body, there are a method of applying an adhesive to the surface or on the surface of an aluminum material having a surface treatment film with unevenness and then bonding by laminating a resin composition, a method of applying a resin composition to the surface or on the surface of an aluminum material having a surface treatment film with unevenness and bonding by thermocompression bonding, a method of applying a resin composition to the surface or on the surface of an aluminum material having a surface treatment film with unevenness and melting the resin by laser heating to bond the aluminum material and the resin molded body, a method of setting an aluminum material having a surface treatment film with unevenness in an injection mold and insert molding the melted resin in this mold to bond (hereinafter referred to as injection molding bonding), a method of forming a coating film on the surface or on the surface of an aluminum material by contacting a resin paint with the surface or on the surface of an aluminum material having a surface treatment film with unevenness and then curing it, and the like.

[0070] The thermoplastic resin can be selected from known thermoplastic resins according to the application. For example, one or more suitable ones can be selected from polyamide resins, polycarbonate resins, polyvinyl resins, polyphenylene sulfide resins, polyacrylic resins, polyester resins, polyacetal resins, acrylonitrile-butadiene-styrene copolymer resins, polystyrene resins, polyimide resins, etc., but it is not limited thereto.

[0071] The thermosetting resin can be selected from known thermosetting resins according to the application. For example, one or more suitable ones can be selected from phenol resins, epoxy resins, urea resins, melamine resins, etc., but it is not limited thereto.

[0072] The thermoplastic elastomer can be selected from known thermoplastic elastomers according to the application. For example, one or more suitable ones can be selected from polyester-based elastomers, vinyl chloride-based elastomers, polyamide-based elastomers, etc., but it is not limited thereto.

[0073] The resin paint can be selected from known resin paints according to the application. For example, one or more suitable ones can be selected from epoxy resins, acrylic resins, polyester resins, urethane resins, etc., but it is not limited thereto. The paint may optionally contain components such as pigments, dispersants, plasticizers, solvents, etc.

[0074] The adhesive can be appropriately selected from, for example, vinyl chloride resin adhesives, vinyl acetate resin adhesives, polyvinyl alcohol adhesives, polyacrylic adhesives, polyamide adhesives, cellulose adhesives, urea resin adhesives, melamine resin adhesives, phenol resin adhesives, epoxy resin adhesives, silicone resin adhesives, polyester adhesives, polyurethane adhesives, chloroprene rubber adhesives, nitrile rubber adhesives, styrene-butadiene rubber adhesives, silicone rubber adhesives, acrylic rubber adhesives, urethane rubber adhesives, hot melt adhesives, etc., and one or more appropriate ones can be selected, but it is not limited thereto.

[0075] The above-mentioned thermoplastic resin, thermosetting resin, thermoplastic elastomer, resin coating, and adhesive may contain known fillers. For example, appropriate ones can be selected from glass fibers, carbon fibers, metal fibers, ceramic fibers, glass beads, carbon powder, metal powder, ceramic powder, aluminum oxide powder, etc., and one or more appropriate ones can be selected, but it is not limited thereto. The type, content, and shape of the filler are not particularly limited.

[0076] <Use of the bonded body> The bonded body is useful as a material for automotive components, aircraft components, electronic device components, mobile device components, OA device components, household appliance components, and medical device components. The surface-treated aluminum material with unevenness can improve not only the bonding strength with the resin but also the adhesion of plating films and the like. Note that the bonded body is not limited to the above-mentioned uses. For example, adhesive bonding with CFRP (insulation + adhesion), lubricating coating base (wear resistance + solid lubricant retention), al umite catalyst (since the unevenness on the outermost surface is usually larger than that of ordinary alumite, the loading amount is large), heat sink (heat dissipation + adhesiveness), etc., and can be used for various applications.

Examples

[0077] Examples are given below together with comparative examples to specifically explain the present invention and its effects. Note that the base materials used in the examples and the chemicals used in all the treatments were arbitrarily selected from commercially available materials and reagents, and do not limit the actual applications of the present invention.

[0078] In the production of the bonded bodies of aluminum materials and resin molded bodies according to Examples 1 to 9 and Comparative Examples 1 to 4, unless otherwise specified, aluminum materials with a width of 20 mm × a length of 45 mm × a thickness of 1.5 mm were used as the aluminum materials. As the aluminum materials for corrosion resistance evaluation, aluminum materials with a width of 70 mm × a length of 150 mm × a thickness of 1.5 mm were used. The evaluation area was made to be 50 mm in width × 100 mm in length using masking tape. The aluminum materials for corrosion resistance evaluation were produced through each step not including the following injection molding bonding step.

[0079] <Method for producing a bonded body of an aluminum material and a resin molded body> Unless otherwise specified, the bonded bodies according to Examples 1 to 9 and Comparative Examples 1 to 4 were produced through the following steps: surface cleaning step → first step → second step → third step → injection molding bonding step. Each treatment in the treatment steps is described below.

[0080] (Surface cleaning step) In the surface cleaning step, after alkaline degreasing (Ridoline F53 manufactured by Nippon Parkerizing Co., Ltd., 15 g / L (solid content concentration), 60 °C, immersion time 3 minutes), pickling (5% nitric acid, 30 °C, immersion time 1 minute) was carried out, and water washing was carried out after each step.

[0081] (First step) In the first step, the aluminum material was immersed in a surface treatment agent containing lithium ions described below, and then water washing was carried out. The pH was adjusted using a nitric acid aqueous solution and a sodium hydroxide aqueous solution.

[0082] (Second step) In the second step, the aluminum material was immersed in an acidic aqueous solution containing an inorganic acid described below, and then water washing and drying were carried out.

[0083] (Third Process) In the third process, an aluminum material was immersed in the acidic aqueous solution described below, an anodizing treatment was performed with the aluminum material as the anode and a platinum plate as the cathode, and then water washing and drying were carried out.

[0084] (Injection Molding Bonding Process) In the injection molding bonding process, polyphenylene sulfide resin (PPS resin) containing 30% glass fiber was injection molded onto the aluminum material after the above process. An electric servo injection molding machine (Si-50III) manufactured by Toyo Machine & Metal Co., Ltd. was used for injection molding. The injection molding conditions were preheat at 125 °C, molding temperature at 320 °C, mold temperature at 135 °C, injection speed at 30 mm / second, injection pressure at 1000 kgf, holding pressure at 1200 kgf, and cooling time at 15 seconds. The dimensions of the molded PPS resin were width 10 mm × length 45 mm × thickness 3 mm. Also, the bonding area between the aluminum material and the PPS resin was 10 mm × 5 mm.

[0085] Hereinafter, based on the above-described aluminum material and treatment process, bonded bodies of the aluminum materials according to Examples 1 to 9 and Comparative Examples 1 to 4 and resin molded bodies were manufactured. The procedures and the like in the examples and comparative examples are described below.

[0086] [Example 1] As the aluminum material, A5052 standardized by JIS H 4000 was used. As the first process, the aluminum material was immersed for 300 seconds using the following treatment liquid (1). As the second process, the aluminum material was immersed for 180 seconds using the following treatment liquid (2). As the third process, the aluminum material was subjected to anodizing treatment for 1.5 minutes at a current density of 1.3 A / dm 2 Thus, a bonded body 1 of the aluminum material and the resin molded body according to Example 1 was obtained.

[0087] Treatment liquid (1): Lithium chloride to a concentration of 3.0 mol / L and magnesium nitrate hexahydrate to a concentration of 0.1 mol / L were added to ion-exchanged water. While measuring the pH with a handy pH meter (Portable pH meter HM-30P manufactured by Toa DK Kogyo Co., Ltd.) and a pH measurement electrode (GST-2739C manufactured by the same company), nitric acid and sodium hydroxide were used to adjust the pH of the treatment liquid to pH 10.0 and adjusted to the target volume. The temperature of the treatment liquid (1) was set at 60°C.

[0088] Treatment liquid (2): 67.5% nitric acid was added to ion-exchanged water so that the nitric acid concentration became 6.5 mol / L. Note that pH adjustment was not performed. The temperature of the treatment liquid (2) was set at 50°C.

[0089] Treatment liquid (3): 75% sulfuric acid was added to ion-exchanged water so that the sulfuric acid concentration became 150 g / L. The temperature of the treatment liquid (3) was adjusted to 20°C.

[0090] [Example 2] The bonded body 2 was manufactured in the same manner as in Example 1 except that the constant current electrolysis time in the third step was changed to 3 minutes.

[0091] [Example 3] The bonded body 3 was manufactured in the same manner as in Example 1 except that the constant current electrolysis time in the third step was changed to 15 minutes. The surface and cross-section of the bonded body 3 were observed with an electron microscope. The results are shown in FIGS. 3 to 6.

[0092] [Example 4] The bonded body 4 was manufactured in the same manner as in Example 3 except that the immersion time in the second step was changed to 60 seconds.

[0093] [Example 5] The bonded body 5 was manufactured in the same manner as in Example 3 except that the immersion time in the second step was changed to 300 seconds.

[0094] [Example 6] The bonded body 6 was manufactured in the same manner as in Example 1 except that the treatment conditions in the third step were changed as follows. As the third step, an aluminum material was anodized using the following treatment liquid (4) with an alternating current superposed on a direct current; 100 A / m 2 , direct current; 100 A / m 2 until the anodic oxide film thickness reached 5 μm. Treatment liquid (4): Oxalic acid was added to ion-exchanged water so that the oxalic acid concentration became 30 g / L. The temperature of treatment liquid (4) was 28°C.

[0095] [Example 7] A bonded body 7 was produced in the same manner as in Example 3, except that the aluminum material was changed to A3003 standardized by JIS H4000.

[0096] [Example 8] A bonded body 8 was produced in the same manner as in Example 3, except that the aluminum material was changed to A6063 standardized by JIS H4000.

[0097] [Example 9] A bonded body 9 was produced in the same manner as in Example 3, except that the aluminum material was changed to ADC6 standardized by JIS H 5302.

[0098] [Comparative Example 1] A comparative bonded body 1 was produced in the same manner as in Example 3, except that the first and second steps were not performed.

[0099] [Comparative Example 2] A comparative bonded body 2 was produced in the same manner as in Comparative Example 1, except that the treatment conditions in the third step were changed as follows. As the third step, an aluminum material was anodized at a voltage of 15 V for 20 minutes using the following treatment liquid (5). Treatment liquid (5): 75% phosphoric acid was added to ion-exchanged water so that the phosphoric acid concentration became 120 g / L. The temperature of treatment liquid (5) was 25°C.

[0100] [Comparative Example 3] A comparative bonded body 3 was produced in the same manner as in Example 1, except that the third step was not performed.

[0101] [Comparative Example 4] A comparative bonded body 4 was produced in the same manner as in Comparative Example 1, except that the processing conditions of the third step were changed as follows. As the third step, after anodizing the aluminum material with the above treatment liquid (5) at a voltage of 15 V for 20 minutes, followed by washing with water, and further, anodizing the aluminum material with the above treatment liquid (3) at a current density of 1.3 A / dm 2 for 15 minutes.

[0102] [Tensile shear test] For the bonded bodies 1 to 9 and comparative bonded bodies 1 to 4 produced as described above, the bonding strength was evaluated by the tensile shear test method standardized in ISO19095-3. The tensile shear test was performed using an autograph precision universal testing machine (AG-100kNX) manufactured by Shimadzu Corporation. The evaluation was carried out under the conditions of room temperature 25°C and a tensile speed of 10 mm / min. The tensile shear strength (bonding strength: MPa) was calculated as the breaking load (N) / bonding area (50 mm 2 ). The fracture mode of the joint between the aluminum material and the resin cured product after the tensile shear test was visually examined.

[0103] The primary bonding strength evaluation was performed on the bonded bodies produced by performing the injection molding bonding process within 2 days after the production of each aluminum material. The secondary bonding strength evaluation was performed on the bonded bodies produced by performing the injection molding bonding process 2 weeks after the production of each aluminum material. Also, the evaluation was carried out according to the following criteria. A: When the resin molded body remained in a fracture mode with an area of 70% or more with respect to the bonding area on the base material side B: When the resin molded body remained in a fracture mode with an area of more than 10% and less than 70% with respect to the bonding area on the base material side C: When the resin molded body remained in a fracture mode with an area of less than 10% with respect to the bonding area on the base material side in the case When the bonding strength is 30 MPa or more and the failure mode of the bonded part is evaluated as A, it is defined that the bonding strength between the aluminum material and the resin molded body is excellent. The results are shown in Table 1.

[0104] (Corrosion resistance evaluation) Regarding the aluminum materials of Examples 1 to 9 and Comparative Examples 1 to 4, the corrosion resistance by the salt spray test was evaluated as follows. Within 1 day after producing each aluminum material, it was subjected to a 96-hour salt spray test in accordance with JIS Z 2371. Then, after washing the aluminum material with ion-exchanged water and drying it, the corrosion area ratio was measured. Specifically, the area ratio was measured by image analysis of the corroded surface and evaluated according to the following criteria. A or more was considered a pass. The results are shown in Table 1. S: The corrosion area ratio is less than 10% A: The corrosion area ratio is 10% or more and less than 30% B: The corrosion area ratio is 30% or more and less than 50% C: The corrosion area ratio is 50% or more

[0105]

Table 1

Claims

1. A first step of bringing an aluminum material into contact with a surface treatment agent containing a lithium ion source and an alkali source, a second step of bringing an acidic aqueous solution containing an inorganic acid into contact with the surface of the aluminum material that has been brought into contact with the surface treatment agent, and a third step of performing an anodizing treatment on the aluminum material that has been brought into contact with the acidic aqueous solution to form an anodic oxide film having unevenness on the surface. A method for manufacturing an aluminum material having a surface treatment film, which includes these steps.

2. The method for manufacturing an aluminum material having a surface treatment film according to Claim 1, wherein the surface of the aluminum material satisfies the following requirements. (1) The thickness of the anodic oxide film is more than 0.1 μm. (2) The average value a of the distances between adjacent convex portions of the unevenness is 50 to 1000 nm, and the aspect ratio b / a with the average value b of the recess depths is 2 or more and 50 or less. (3) It has fine pores with a diameter of 5 to 30 nm.

3. A method for manufacturing a bonded body of an aluminum material and a resin molded body, which includes a step of inserting a resin composition into the unevenness on the surface of the aluminum material having a surface treatment film obtained by the manufacturing method according to Claim 1 or 2.

4. A bonded body of an aluminum material and a resin molded body obtained by the manufacturing method according to Claim 3.

5. An aluminum material having a surface treatment film, wherein the surface treatment film is an anodic oxide film, and the surface of the aluminum material has unevenness and satisfies the following requirements. An aluminum material having a surface treatment film. (1) The thickness of the anodic oxide film is more than 0.1 μm. (2) The average value a of the distances between adjacent convex portions of the unevenness is 50 to 1000 nm, and the aspect ratio b / a with the average value b of the recess depths is 2 or more and 50 or less. (3) It has fine pores with a diameter of 5 to 30 nm.

6. A bonded body of an aluminum material having a surface treatment film according to Claim 5 and a resin molded body.

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