Aluminum material having surface-treated film and production method therefor, and joined body of aluminum material and resin molded body using same and production method therefor

Abstract

The present invention addresses the problem of providing: a joined body of a resin molded body and an aluminum material having excellent joining strength to the resin molded body and excellent corrosion resistance; and an aluminum material that can provide said joined body and has a surface-treated film.　The problem is solved by a production method for an aluminum material having a surface-treated film, the production method comprising: a first step for bringing an aluminum material into contact with a surface treatment agent containing a lithium ion source and an alkali source; a second step for 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 for forming an anodic oxide film having irregularities on the surface thereof by performing anodic oxidation treatment on the aluminum material that has been brought into contact with the acidic aqueous solution.

Description

Aluminum material having a surface treatment film and its manufacturing method, and joint body of aluminum material and resin molded body using the same and its manufacturing method

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

[0002] In recent years, there has been an increasing demand for bonded articles formed by bonding an aluminum alloy substrate and a resin. Examples of such bonded articles include a bonded article in which an aluminum alloy molded article is bonded to another member via a resin adhesive, and a bonded article in which an aluminum alloy molded article is directly bonded to a resin member. However, such bonded articles formed by bonding dissimilar materials often have insufficient bond strength.

[0003] Non-Patent Document 1 describes a method for anodizing an aluminum alloy substrate using a phosphoric acid aqueous solution as an electrolyte to improve the bonding strength between an aluminum alloy molded product and a resin. However, this method has problems in industrial use, such as the difficulty in consistently producing bonded products with high bonding strength and the decrease in adhesive strength due to changes over time after anodizing (short lifetime).

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

[0005] Japanese Patent Application Laid-Open No. 2021-75763

[0006] Yukiji Takada; Surface Technology, Vol. 52, No. 1, 2001 Surface Technology for Space Equipment

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

[0008] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by an aluminum material having a surface treatment film produced by a production method including a first step using a surface treatment agent containing a lithium ion source and an alkali source, a second step using an acidic aqueous solution containing an inorganic acid, and a third step performing anodizing treatment, and have thus completed the present invention.

[0009] [1] A method for producing an aluminum material having a surface treatment film, comprising: a first step of contacting an aluminum material with a surface treatment agent containing a lithium ion source and an alkali source; a second step of contacting the surface of the aluminum material that has been contacted with the surface treatment agent with an acidic aqueous solution containing an inorganic acid; and a third step of anodizing the aluminum material that has been contacted with the acidic aqueous solution to form an anodized film having irregularities on the surface. [2] A method for producing 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 anodized film is greater than 0.1 μm. (2) The average value a of the distances between adjacent convex portions of the irregularities is 50 to 1,000 nm, and the aspect ratio b / a of the average depth b of the concave portions is 2 or more and 50 or less. (3) The aluminum material has micropores with diameters of 5 to 30 nm. [3] A method for producing a joined body of an aluminum material and a resin molded product, comprising a step of inserting a resin composition into the irregularities on the surface of the aluminum material having a surface treatment film obtained by the production method according to [1] or [2]. [4] A bonded body of an aluminum material and a resin molded body, obtained by the manufacturing method described in [3]. [5] An aluminum material having a surface treatment film, wherein the surface treatment film is an anodized film, and the surface of the aluminum material has irregularities and satisfies the following requirements: (1) The thickness of the anodized film exceeds 0.1 μm. (2) The average value a of the distances between adjacent convex portions of the irregularities is 50 to 1000 nm, and the aspect ratio b / a of the average depth b of the concave portions is 2 or more and 50 or less. (3) The aluminum material has micropores with a diameter of 5 to 30 nm. [6] A bonded body of an aluminum material having a surface treatment film described in [5] and a resin molded body.

[0010] According to the present invention, it is possible to provide an aluminum material having a surface treatment film that can stably obtain high bonding strength when bonded to a resin molded body and that has excellent corrosion resistance, and a bonded body of the aluminum material and a resin molded body.

[0011] 1 is a schematic diagram for explaining the shape of the irregularities formed on the surface of the substrate by the first and second steps and the measurement points for the distance between adjacent convex portions. FIG. 2 is a schematic diagram of the cross-sectional structure of the irregularities formed on the surface of the substrate by the first and second steps, and is a schematic diagram for explaining a method for measuring the distance between adjacent convex portions and the depth of a recess. FIG. 3 is a photograph (drawing substitute photograph) of the surface of the substrate in Example 3 observed at 50,000x electron microscope magnification. FIG. 4 is a photograph (drawing substitute photograph) of the surface of the substrate in Example 3 observed at 200,000x electron microscope magnification. FIG. 5 is a photograph (drawing substitute photograph) of the cross section of the substrate in Example 3 observed at 10,000x electron microscope magnification. FIG. 6 is a photograph (drawing substitute photograph) of the cross section of the substrate in Example 3 observed at 50,000x electron microscope magnification.

[0012] DETAILED DESCRIPTION OF THE INVENTION One embodiment of the present invention is an aluminum material having a surface treatment film, wherein the surface treatment film is an anodic oxide film.

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

[0014] The aluminum or aluminum alloy is not particularly limited, and any aluminum material used industrially can be used. Aluminum materials typically refer to materials containing 60% or more aluminum, and examples of alloy components other than aluminum include magnesium, silicon, titanium, chromium, manganese, iron, nickel, copper, and zinc. Specific examples include A1050, A2014, A2024, A3003, A5052, A5N01, A6061, A6063, A7075, AC4A, and ADC12, which are specified in JIS H 4000, JIS H 5302, and JIS H 5202.

[0015] The shape of the aluminum material is not particularly limited, and may be, for example, a plate, rod, strip, tube, wire, fiber, foil, or lump, or may be a structure combining these, but is preferably a shape that can be bonded to a resin. The aluminum material includes all intermediate products and finished products. It may be a substrate containing aluminum material and other materials. Of course, it may be composed only of aluminum material. Examples of materials other than aluminum material include, but are not limited to, metals other than aluminum, resins, rubber, wood, ceramics, composite materials, etc. Furthermore, the bonding method is not particularly limited. Furthermore, when bonding to a resin molded body, the shape of the bonding surface of the aluminum material may be flat, curved, etc., but is not particularly limited.

[0016] The aluminum material may be subjected to plastic working, cutting, blasting, polishing, electric discharge machining, drilling, heat treatment (age hardening treatment, solution treatment, etc.), and surface treatment (chemical conversion treatment, plating treatment, etc.), but it is preferable to remove these coating components by polishing, chemical treatment, etc. before forming the asperities described below.

[0017] The aluminum material has an anodized film on its surface, which is formed in the third step described below.

[0018] In this embodiment, the aluminum material has an uneven surface and has the following characteristics (1) to (3): (1) the thickness of the anodized film exceeds 0.1 μm; (2) the average distance a between adjacent convex portions of the unevenness is 50 to 1000 nm, and the aspect ratio b / a of the average concave depth b is 2 or more and 50 or less; (3) the aluminum material has micropores with a diameter of 5 to 30 nm. As a result, when an aluminum material having an anodized film with unevenness on its surface is used to manufacture a bonded body of an 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 a bonded body of aluminum material and resin molded body having excellent corrosion resistance can be formed.

[0019] The thickness of the anodized film is more than 0.1 μm, preferably 0.5 μm or more, and more preferably 1.0 μm or more. When the anodized film has 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, and may be 50 μm or less, or may be 10 μm or less.

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

[0021] (Aspect Ratio) The aspect ratio according to this embodiment is calculated by the ratio b / a, where a is the average distance between adjacent convex portions of the irregularities and b is the average depth of the concave portions. An aspect ratio of 2 or more means that irregularities exist in which the average concave depth b is at least twice as large as the a. The average distance between adjacent convex portions of the irregularities can be measured from a photograph of the surface of an aluminum material having an anodized coating taken with an electron microscope. Circular or elliptical holes are observed on the surface of the aluminum material, as shown in FIG. 1, and constitute the surface irregularities. In other words, the hole portions become the concave portions of the surface irregularities. The holes may not only be formed extending perpendicularly to the surface, but also obliquely. Furthermore, the holes may be formed in a meandering manner in the depth direction. The average distance between adjacent convex portions of the irregularities is the average diameter (FIG. 1a) or minor axis (FIG. 1b) of the circular or elliptical openings formed on the surface, and is the average value of 20 arbitrary convex-to-convex distances observed with an electron microscope. In some cases, there may be overlapping recesses, and in such cases, it is preferable to measure a portion where the recesses do not overlap. In order to determine the diameter and minor axis of the opening, it is preferable to use an electron microscope observation at a magnification of 10,000 times or more and 50,000 times or less.

[0022] When a large number of irregularities are to be measured, the average value a of the distance between adjacent convex portions of the irregularities can also be measured from a photograph of the cross-sectional structure that appears at the cut surface when the substrate is cut perpendicular to the actual surface, taken with an electron microscope. In this case, the average value of the distance between adjacent convex portions of the irregularities is the average value of c in Figure 2, and the average value of the distance between any 10 convex portions is taken as the average value of the distance between adjacent convex portions of the irregularities. To determine the distance between convex portions, it is preferable to use a magnification of 10,000 times or more and 50,000 times or less for observation with an electron microscope. It is more preferable to measure the average value of the distance between adjacent convex portions of the irregularities from a photograph of the surface of an aluminum material having an anodized coating taken with an electron microscope.

[0023] The average depth b of the recesses is measured from a photograph taken by electron microscopy of the cross-sectional structure that appears at the cut surface when an aluminum material having an anodized coating is cut perpendicular to the actual surface. To determine the depth of the irregularities, it is preferable to use a magnification of 10,000 to 50,000 times in the electron microscope observation. Since the holes can be formed not only perpendicular to the surface but also obliquely, the cross-sectional observation photograph may show recesses that are observed intermittently from the outermost surface to the depth direction, as shown in Figure 2. The average depth b of the recesses is the average of the length from the top to the deepest part of the protrusions in the formed irregularities (d in Figure 2) and the length from the outermost surface to the deepest part (e in Figure 2), and the average value of the top 10 deepest recesses is taken as the average 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 even 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 depth b 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 even more preferably 0.3 μm or more and 8 μm or less.

[0026] From the viewpoint of further improving the bonding strength between the aluminum material and the resin, the aspect ratio specified above is at least 2, preferably at least 3, and more preferably at least 4. Furthermore, if the aspect ratio exceeds 50, the strength of the aluminum material itself may decrease.

[0027] The number of irregularities having the above aspect ratio on the surface of the aluminum material is determined by observing any 10 points on the surface and cross section of the aluminum material. ２ The unevenness does not need to be present on the entire surface of the aluminum material, but only needs to be present on the portion that will bond with the resin described below. ２ The number of the contact irregularities is preferably 1 or more and 200 or less.

[0028] (Micropores) In addition to the irregularities described in (2) above, an aluminum material having a surface treatment film has micropores with an average diameter of 5 to 30 nm observed by surface observation using an electron microscope. The micropores are pores oriented in the thickness direction of the surface treatment film and can be measured from photographs of the surface of the aluminum material taken with an electron microscope. The micropores may be located in any of the convex portions, concave portions, or side portions of the irregularities described in (2) above. To determine the average diameter of the micropores, it is preferable to use an electron microscope with a magnification of 200,000 times or more.

[0029] The average diameter of the micropores is the average diameter or minor axis of the circular or elliptical openings formed on the surface, and is the average value of 20 arbitrary locations observed with an electron microscope.

[0030] It is sufficient that one or more micropores can be confirmed by observing any 10 points on the surface of the aluminum material. More specifically, the number of micropores on the surface of the aluminum material having a surface treatment film is 0.1 μm2. ２The number of micropores per aluminum material is preferably 5 or more and preferably 30 or less. The micropores do not need to be present over the entire surface of the aluminum material, as long as they are present at least in the portion that will bond with the resin described below.

[0031] <Method for producing surface-treated aluminum material> Next, a method for producing a surface-treated aluminum material having an anodized film on its surface will be described. Examples of a method for producing a surface-treated aluminum material having an anodized film on its surface and further having irregularities include a method comprising the following first to third steps: First step: a step of contacting an aluminum material with a surface treatment agent containing a lithium ion source and an alkali source; Second step: a step of contacting the surface of the aluminum material that has been contacted with the surface treatment agent with an acidic aqueous solution containing an inorganic acid; Third step: a step of anodizing the aluminum material that has been contacted with the acidic aqueous solution to form an anodized film that has irregularities on its surface.

[0032] (First Step) In the first step, a lithium-containing film containing lithium element is formed by contacting the surface of an aluminum material with a surface treatment agent containing a lithium ion source and an alkali source. This involves a dissolution reaction of a passivation film, including an oxide film, on the surface of the aluminum material. The lithium-containing film can be formed using a known method. Examples include, but are not limited to, boehmite treatment and chemical conversion treatment. Here, the lithium-containing film containing lithium element includes hydroxide films, oxide films, hydrated oxide films, etc., containing metals derived from the aluminum material. As the treatment method, for example, the methods described in JP-A-48-89138 and JP-A-53-11841 can be used.

[0033] (Lithium Ion Source) The lithium ion source can be one or more appropriately selected from lithium hydroxides, chlorides, carbonates, bicarbonates, nitrates, nitrites, sulfates, persulfates, bromides, bromates, etc. The surface treatment agent used in the first step contains lithium ions at a concentration of preferably 0.001 mol / L to 5.00 mol / L, more preferably 0.10 mol / L to 4.00 mol / L, and even more preferably 0.50 mol / L to 3.50 mol / L. The lithium ion concentration may exceed the saturated 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 metals or alkaline earth metals are not particularly limited, and one or more suitable ones can be selected from lithium, sodium, magnesium, potassium, calcium, etc.

[0035] When the surface treatment agent used in the first step uses an alkali metal or alkaline earth metal hydroxide as the alkali source, the molar concentration of the alkali source is usually 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 even more preferably 0.01 mol / L or more and 3.00 mol / L or less. The hydroxide concentration of the alkali metal or alkaline earth metal may exceed the saturated solubility.

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

[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 0.005 mol / L or more and 0.90 mol / L or less, and even more preferably 0.01 mol / L or more and 0.80 mol / L or less.

[0038] As the surface treatment agent in the first step, one component of the hydroxide of an alkali metal or alkaline earth metal and the water-soluble amine compound may be used alone, or several components may be used in combination.

[0039] The surface treatment agent in the first step desirably does not contain zinc ions or silicate ions. If zinc ions are present, a zinc-substituted coating may form on the surface of the aluminum material, making it impossible to obtain the desired unevenness. Furthermore, if silicate ions are present, a silicon-containing coating may form on the surface of the aluminum material, making it impossible to obtain the desired unevenness. Furthermore, it is desirable that the agent does not contain transition metal ions such as copper, iron, nickel, and tin. Note that hydroxides of alkali metals and alkaline earth metals, as well as sodium, potassium, magnesium, calcium, and the like supplied from these salts, may be contained in the formed surface treatment coating.

[0040] The surface treatment agent for 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. The surface treatment agent may contain elements derived from the aluminum material and water, such as aluminum, magnesium, silicon, titanium, chromium, manganese, iron, nickel, copper, and zinc.

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

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

[0043] The method of contacting the aluminum material with the surface treatment agent in the first step includes immersion and spray treatment. By contacting the aluminum material with the surface treatment agent, it is possible to form a coating containing lithium element on the aluminum material, but 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 to 1800 seconds, more preferably 10 to 1200 seconds. After the first step, a water-washing step and a drying step may be carried out as necessary.

[0045] (Second Step) The acidic aqueous solution used in the second step contains an inorganic acid. The inorganic acid may be one or more suitable acids selected from sulfuric acid, nitric acid, hydrochloric acid, amidosulfuric acid, etc., but is not limited thereto. The acidic aqueous solution may also contain an organic acid, an inorganic acid salt, an organic acid salt, etc., but preferably does not contain a transition metal. The organic acid may be one or more suitable acids selected from formic acid, citric acid, oxalic acid, malic acid, succinic acid, malonic acid, ethylenediaminetetraacetic acid, gluconic acid, etc., but is not limited thereto. The inorganic acid salt and organic acid salt may be one or more suitable acids selected from alkali metal salts, alkaline earth metal salts, and ammonium salts of the inorganic acid and organic acid, but is not limited thereto. The acidic aqueous solution may contain one or more of the inorganic acids, organic acids, or salts thereof. Although the above-mentioned unevenness may be formed even when an acidic aqueous solution of the organic acid, inorganic acid salt, or organic acid salt is used alone, an acidic aqueous solution of an inorganic acid alone is preferred from an industrial viewpoint.

[0046] The total content of the components containing 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, based on the total amount of the acidic aqueous solution.

[0047] The acidic aqueous solution in the second step may contain a surfactant, a chelating agent, etc. When these other components are added, the total content thereof is preferably 10.0 mass % or less based on the total amount of the acidic aqueous solution.

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

[0049] In the second step, the aluminum material is brought into contact with the acidic aqueous solution containing an inorganic acid by immersion or spraying. Electrolysis may also be used 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 as long as it is acidic, and is preferably adjusted to, for example, pH 6.0 or less, more preferably pH 3.0 or less, and even more preferably pH 1 or less. The contact time is preferably 1 second to 1800 seconds, more preferably 5 seconds to 1200 seconds, and even more preferably 10 seconds to 900 seconds. After the second step, a water-washing step and a drying step are usually carried out. Ultrasonic waves may be used in the water-washing step. The drying step may be natural drying, or may use a dryer, air blower, oven, or the like.

[0051] Drying may be carried out after the second step and before the third step, or the third step may be carried out 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 carry out the second step between the first step and the third step.

[0052] (Third Step) A known anodizing method can be appropriately adopted for the anodizing treatment in the third step. 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 materials such as platinum, lead, stainless steel, carbon, and aluminum.

[0055] The electrolytic solution used in anodizing treatment can be an acidic solution or an alkaline solution. Examples of acidic solutions include solutions of chromic acid, oxalic acid, sulfuric acid, and the like, and these can be used alone or in combination. However, from the viewpoint of the corrosion resistance of the coating, it is desirable not to use a phosphoric acid solution. Examples of mixed acid baths include mixtures of the above-mentioned acidic solutions, as well as sulfosalicylic acid-sulfuric acid and sulfosalicylic acid-maleic acid systems. Examples of alkaline solutions include ammonia-fluoride systems, alkali-peroxide systems, and sodium phosphate systems. Of these electrolytic solutions, acidic solutions such as oxalic acid and sulfuric acid solutions are preferred.

[0056] For example, when a sulfuric acid aqueous solution is used as the acidic solution, the concentration of the acidic solution is preferably 0.1% by mass to 50.0% by mass, more preferably 1.0% by mass to 40.0% by mass, and even more preferably 5.0% by mass to 30.0% by mass. When an oxalic acid aqueous solution is used, the concentration is preferably 0.1% by mass to 40.0% by mass, more preferably 0.5% by mass to 30.0% by mass, and even more preferably 1.0% by mass to 20.0% by mass. The temperature of the acidic solution is preferably -10 to 80°C, more preferably -10 to 60°C. By performing anodizing at this temperature, an anodized film having micropores of 5 to 30 nm is formed. This further expands the surface area of ​​the aluminum material surface, facilitating contact with the resin, and the resin in contact with the surface-treated aluminum material surface penetrates (bites into) the aluminum material surface, making it possible to easily and firmly bond the aluminum material and the resin material. The electrolytic solution of the third step can be easily prepared by diluting the above components with ion-exchanged water, industrial water, tap water, etc. The electrolytic solution may contain elements such as aluminum, magnesium, silicon, titanium, chromium, manganese, iron, nickel, copper, and zinc derived from the aluminum material and water. The components used in the first and second steps may also be mixed in. Additives such as surfactants, chelating agents, and organic compounds may also be added to the electrolytic solution of the third step. When these other components are added, the total content is preferably 10.0 mass% or less of 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, and may be, for example, 0.01 to 10 A / dm ２ is preferably 0.05 to 5 A / dm ２ is preferably 0.1 to 2.5 A / dm ２It is even more preferable that the current density of the electrolysis is less than the lower limit, the rate of formation of the anodic oxide film tends to be very slow, while if it exceeds the upper limit, the dissolution of the anodic oxide film becomes intense, and the irregularities tend to be smoothed out. The time for the electrolysis in the anodizing treatment is preferably 30 seconds to 100 minutes, and more preferably 60 seconds to 60 minutes. The current density and the time for the electrolysis can be adjusted appropriately depending on the required thickness of the anodic oxide film.

[0058] The anodizing treatment may be performed multiple times, or multiple times using different electrolytic solutions. From the viewpoint of improving corrosion resistance, the thickness of the anodized film may be greater than 0.1 μm and may be 0.3 μm or greater, preferably 0.5 μm or greater, more preferably 1 μm or greater, more preferably 2 μm or greater, and even more preferably 3 μm or greater. Furthermore, the thickness of the anodized 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 anodized film is 0.1 μm or less, sufficient corrosion resistance cannot be obtained, and if it exceeds 100 μm, cracks are likely to occur, which may result in reduced corrosion resistance. The anodized film in the third step is formed along the surface irregularities formed in the first and second steps. Therefore, the anodized film is formed on all of the convex portions, concave portions, and side portions of the irregularities. The thickness of the anodized film can be measured from a photograph of the cross-sectional structure that appears at the cut surface when an aluminum material having the anodized film is cut perpendicular to the actual surface, observed with an electron microscope, optical microscope, or the like. To determine the thickness of the anodized film, a magnification of 100 times or more and 50,000 times or less is preferable for microscopic observation. The thickness of the anodized film is the average length from the top of the convex portion of the formed unevenness to the deepest portion of the anodized film, and is the average value of any 10 locations observed with the microscope. The thickness of the anodized film may be thinner than the average depth b of the concave portions.

[0059] After the third step, a water-washing step and a drying step are usually carried out. Ultrasonic waves may be used in the water-washing step. The drying step may be natural drying or may use a dryer, air blower, oven, or the like.

[0060] In the manufacturing method according to the embodiment of the present invention, the aluminum material may be treated entirely or partially, and in order to obtain excellent bonding strength with the resin, it is sufficient to treat only the portion to be bonded to the resin.

[0061] In the method for producing a surface-treated aluminum material according to an embodiment of the present invention, other steps may be present. Examples of such other steps include a step of processing the surface of the aluminum material or a step of cleaning the surface before the first step. Each step may be repeated if necessary. Each step will be described in detail below.

[0062] (Surface Treatment Step) Before the first step, the aluminum material may be subjected to a roughening treatment in advance by 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 chemical method. The uneven shape formed after these processes is not important.

[0063] (Surface Cleaning Step) Before the first step, the aluminum material may be subjected to a pretreatment consisting of a degreasing treatment, an acid treatment with an acid aqueous solution, and / or an alkali treatment with an alkali solution in order to clean the surface of the aluminum material. The degreasing method is not particularly limited, and for example, a solvent-based, aqueous, or emulsion-based degreasing agent can be used, and may contain an alkali salt, a surfactant, or the like. As a pretreatment method using an 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 mixtures thereof can be used. As a pretreatment method using an alkali treatment, an alkaline reagent such as sodium hydroxide or potassium hydroxide, or a mixture thereof can be used.

[0064] (Post-Treatment Step) After carrying out the third step, the surface of the aluminum material having the surface treatment film may be subjected to a post-treatment step such as sealing (boiling water sealing, pressurized steam sealing, metal salt sealing, triethanolamine-added boiling water sealing, etc.), acid treatment, coloring, dyeing, painting, electrodeposition coating, plating, etc. Furthermore, after forming a bonded body with a resin molded body described below, the sealing, acid treatment, coloring, dyeing, painting, electrodeposition coating, plating, etc. may be carried out.

[0065] (Other Treatment Steps) In addition to the steps described above, other steps may be appropriately performed as necessary. For example, a water washing step may be performed before or after any of the steps (e.g., surface processing step, surface cleaning step, pore forming step, post-treatment step, etc.). Furthermore, a drying step may be appropriately performed after each water washing step.

[0066] <Method for manufacturing a bonded body of an aluminum material and a resin molded body> An aluminum material having a surface treatment film can be bonded to a resin molded body to form a bonded body. The bonded body of a surface-treated aluminum material and a resin molded body contains the resin molded body (cured product) in the unevenness on the surface of the aluminum material having a surface treatment film.

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

[0068] The method for producing a bonded body includes a step of inserting a resin composition into the irregularities present on the surface of an aluminum material having a surface treatment film. After the step of inserting the resin composition into the irregularities, the resin composition is cured by cooling, leaving, or heating to form a bonded body. The bonded body may be composed of only an aluminum material and a resin molded body, or may include an aluminum material, a resin molded body, and a mating material that contacts the resin molded body. The mating material may be any material, including not only resin materials but also metals, rubber, wood, ceramics, and composite materials. The shape of the mating material is not particularly limited and may be a plate, rod, strip, pipe, wire, film, etc.

[0069] Specific methods for producing a bonded body include a method in which an adhesive is applied to the surface or surface of an aluminum material having an uneven surface treatment film, and then a resin composition is applied to bond them together; a method in which a resin composition is applied to the surface or surface of an aluminum material having an uneven surface treatment film and bonded by thermocompression; a method in which a resin composition is applied to the surface or surface of an aluminum material having an uneven surface treatment film and the resin is melted by laser heating to bond the aluminum material and a resin molded body; a method in which an aluminum material having an uneven surface treatment film is set in an injection molding die and the molten resin is insert-molded into this die to bond (hereinafter referred to as injection molding bonding); and a method in which a resin paint is brought into contact with the surface or surface of an aluminum material having an uneven surface treatment film and then cured to form a coating film on the surface or surface of the aluminum material.

[0070] The thermoplastic resin can be selected from known thermoplastic resins depending on the intended use, including, but not limited to, one or more suitable resins selected from polyamide resins, polycarbonate resins, polyvinyl resins, polyphenylene sulfide resins, polyacrylic resins, polyester resins, polyacetal resins, acrylonitrile-butadiene-styrene copolymer resins, polystyrene resins, and polyimide resins.

[0071] The thermosetting resin can be selected from known thermosetting resins depending on the intended use, including, but not limited to, one or more suitable resins selected from phenolic resins, epoxy resins, urea resins, melamine resins, and the like.

[0072] The thermoplastic elastomer can be selected from known thermoplastic elastomers depending on the intended use, and can be, for example, one or more suitable elastomers selected from polyester elastomers, vinyl chloride elastomers, polyamide elastomers, etc., but is not limited thereto.

[0073] The resin coating material can be selected from known resin coating materials depending on the intended use. For example, one or more suitable resins can be selected from epoxy resins, acrylic resins, polyester resins, urethane resins, etc., but are not limited thereto. The coating material may optionally contain components such as pigments, dispersants, plasticizers, and solvents.

[0074] The adhesive may be one or more suitable adhesives 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, phenolic 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., but is not limited to these.

[0075] The thermoplastic resins, thermosetting resins, thermoplastic elastomers, resin coatings, and adhesives may contain known fillers. For example, one or more suitable fillers may be selected from glass fiber, carbon fiber, metal fiber, ceramic fiber, glass beads, carbon powder, metal powder, ceramic powder, aluminum oxide powder, etc., but are not limited thereto. The type, content, and shape of the filler are not particularly limited.

[0076] <Applications of the Joint> The joint is useful as a material for automobile components, aircraft components, electronic components, mobile device components, office automation equipment components, home appliance components, and medical device components. Surface-treated aluminum materials with irregularities can improve not only the bonding strength with resin but also the adhesion of plating films and the like. The joint is not limited to the above-mentioned applications. For example, it can be used for various applications, such as adhesive bonding with CFRP (insulation + adhesion), lubricating paint base (wear resistance + solid lubricant retention), anodized aluminum catalyst (higher loading due to larger irregularities on the outermost surface than regular anodized aluminum), and heat sink (heat dissipation + adhesiveness).

[0077] The present invention and its effects will be specifically described below with reference to examples and comparative examples. Note that the substrates and chemicals used in all treatments in the examples were arbitrarily selected from commercially available materials and reagents, and do not limit the actual use of the present invention.

[0078] In the production of joined bodies of aluminum material and resin molded body according to Examples 1 to 9 and Comparative Examples 1 to 4, unless otherwise specified, an aluminum material measuring 20 mm wide x 45 mm long x 1.5 mm thick was used as the aluminum material. The aluminum material used for corrosion resistance evaluation was an aluminum material measuring 70 mm wide x 150 mm long x 1.5 mm thick. The evaluation area was measured using masking tape to be 50 mm wide x 100 mm long. The aluminum materials used for corrosion resistance evaluation were produced through the following processes excluding the injection molding joining process.

[0079] <Method for manufacturing a joined body of an aluminum material and a resin molded body> Unless otherwise specified, the joined bodies according to Examples 1 to 9 and Comparative Examples 1 to 4 were manufactured through the following steps: surface cleaning step → first step → second step → third step → injection molding joining step. Each step in these steps will be described below.

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

[0081] (First Step) In the first step, the aluminum material was immersed in a surface treatment agent containing lithium ions, which will be described later, and then washed with water. The pH was adjusted using an aqueous solution of nitric acid and an aqueous solution of sodium hydroxide.

[0082] (Second Step) In the second step, the aluminum material was immersed in an acidic aqueous solution containing an inorganic acid, which will be described later, and then washed with water and dried.

[0083] (Third Step) In the third step, the aluminum material was immersed in an acidic aqueous solution described below, and anodization was performed using the aluminum material as the anode and a platinum plate as the cathode, followed by washing with water and drying.

[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 Machinery & Metal Co., Ltd. was used for injection molding. The injection molding conditions were preheat 125°C, molding temperature 320°C, mold temperature 135°C, injection speed 30 mm / sec, injection pressure 1000 kgf, dwell pressure 1200 kgf, and cooling time 15 seconds. The dimensions of the molded PPS resin were 10 mm wide x 45 mm long x 3 mm thick. The bonding area between the aluminum material and the PPS resin was 10 mm x 5 mm.

[0085] Based on the aluminum material and processing steps described above, joined bodies of aluminum material and resin molded body according to Examples 1 to 9 and Comparative Examples 1 to 4 were manufactured. The procedures in the Examples and Comparative Examples are described below.

[0086] [Example 1] A5052 aluminum material specified by JIS H 4000 was used. In the first step, the aluminum material was immersed in the following treatment solution (1) for 300 seconds. In the second step, the aluminum material was immersed in the following treatment solution (2) for 180 seconds. In the third step, the aluminum material was immersed in the following treatment solution (3) at a current density of 1.3 A / dm ２ In this way, a joined body 1 of an aluminum material and a resin molded body according to Example 1 was obtained.

[0087] Treatment solution (1): Lithium chloride (3.0 mol / L) and magnesium nitrate hexahydrate (0.1 mol / L) were added to ion-exchanged water, and the pH of the treatment solution was adjusted to pH 10.0 using nitric acid and sodium hydroxide while measuring the pH with a handy pH meter (portable pH meter HM-30P manufactured by DKK-TOA Corporation) and a pH measurement electrode (GST-2739C manufactured by the same company). The temperature of treatment solution (1) was set to 60°C.

[0088] Treatment solution (2): 67.5% nitric acid was added to ion-exchanged water so that the nitric acid concentration was 6.5 mol / L. No pH adjustment was performed. The temperature of treatment solution (2) was 50°C.

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

[0090] Example 2 A joint body 2 was produced in the same manner as in Example 1, except that the time for constant current electrolysis in the third step was changed to 3 minutes.

[0091] Example 3 A bonded body 3 was produced in the same manner as in Example 1, except that the time for constant current electrolysis 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 Figures 3 to 6.

[0092] Example 4 A bonded body 4 was produced 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 Bonded body 5 was produced 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] A joined body 6 was produced in the same manner as in Example 1, except that the treatment conditions in the third step were changed as follows. In the third step, an aluminum material was subjected to AC / DC superimposed electrolysis using the following treatment solution (4): AC; 100 A / m ２ , DC; 100A / m ２ Anodizing treatment was performed at 100°C until the thickness of the anodized film reached 5 μm. Treatment solution (4): Oxalic acid was added to ion-exchanged water so that the oxalic acid concentration was 30 g / L. The temperature of treatment solution (4) was set to 28°C.

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

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

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

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

[0099] Comparative Example 2 Comparative joint 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. In the third step, an aluminum material was anodized for 20 minutes at a voltage of 15 V using the following treatment solution (5). Treatment solution (5): 75% phosphoric acid was added to ion-exchanged water so that the phosphoric acid concentration was 120 g / L. The temperature of treatment solution (5) was set to 25°C.

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

[0101] Comparative Example 4 Comparative joint 4 was produced in the same manner as in Comparative Example 1, except that the treatment conditions in the third step were changed as follows. In the third step, an aluminum material was anodized using the treatment solution (5) at a voltage of 15 V for 20 minutes, followed by rinsing with water. The aluminum material was then anodized using the treatment solution (3) at a current density of 1.3 A / dm ２ The anodization treatment was carried out at 40°C for 15 minutes.

[0102] (Tensile shear test) The bond strength of the bonded bodies 1 to 9 and the comparative bonded bodies 1 to 4 prepared as described above was evaluated by the tensile shear test method standardized in ISO 19095-3. The tensile shear test was performed using an autograph precision universal testing machine (AG-100kNX) manufactured by Shimadzu Corporation. The evaluation was performed at room temperature of 25°C and at a tensile speed of 10 mm / min. The tensile shear strength (bonding strength: MPa) was calculated by the following formula: breaking load (N) / bonding area (50 mm ２ After the tensile shear test, the fracture morphology of the joint between the aluminum material and the cured resin was visually inspected.

[0103] The primary bond strength evaluation was performed on bonded bodies produced by performing an injection molding joining process within two days after the production of each aluminum material. The secondary bond strength evaluation was performed on bonded bodies produced by performing an injection molding joining process two weeks after the production of each aluminum material. The evaluation was based on the following criteria: A: When the resin molded body had a fracture morphology in which an area remaining was 70% or more of the bonded area on the substrate side; B: When the resin molded body had a fracture morphology in which an area remaining was 10% or more but less than 70% of the bonded area on the substrate side; C: When the resin molded body had a fracture morphology in which an area remaining was less than 10% of the bonded area on the substrate side. When the bond strength was 30 MPa or more and the evaluation of the fracture morphology of the bond was A, the bond strength between the aluminum material and the resin molded body was defined as excellent. The results are shown in Table 1.

[0104] (Evaluation of Corrosion Resistance) The aluminum materials of Examples 1 to 9 and Comparative Examples 1 to 4 were evaluated for corrosion resistance in a salt spray test as follows. Within one day after production, each aluminum material was subjected to a 96-hour salt spray test in accordance with JIS Z 2371, and then the aluminum material was washed with ion-exchanged water and dried, after which 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 grade of A or higher was considered to be acceptable. The results are shown in Table 1. S: Corrosion area ratio less than 10% A: Corrosion area ratio 10% or more but less than 30% B: Corrosion area ratio 30% or more but less than 50% C: Corrosion area ratio 50% or more

[0105]

[0106] Although the present invention will be described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

Claims

1. A method for manufacturing an aluminum material having a surface treatment film, comprising: 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 anodized film having irregularities on the surface.

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 anodized film is more than 0.1 μm. (2) The average value a of the distances between adjacent convex portions of the irregularities is 50 to 1000 nm, and the aspect ratio b / a with the average value b of the depths of the concave portions 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, comprising a step of inserting a resin composition into the irregularities 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 anodized film, and the surface of the aluminum material has irregularities and satisfies the following requirements: (1) The thickness of the anodized film is more than 0.1 μm. (2) The average value a of the distances between adjacent convex portions of the irregularities is 50 to 1000 nm, and the aspect ratio b / a with the average value b of the depths of the concave portions 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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