Metallic member, metal-resin bonded body, and method for manufacturing metallic member

Abstract

Provided is a metal member which has a surface having an uneven structure and satisfies at least one of the requirements (1) to (3) mentioned below. (1) The surface is covered with a hydrophobic film; (2) the surface has a water contact angle of 90° or more; and (3) the surface is in such a state where an organic compound is chemically bound thereto.

Description

[Technical Field]

[0001] The present invention relates to a metal member, a metal-resin bonded body, and a method for manufacturing a metal member. [Background technology]

[0002] As a method for roughening the surface of a metal component, a method has been proposed in which a micrometer-order uneven structure is first formed, and then a nanometer-order uneven structure is formed on the surface of the micrometer-order uneven structure (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 158820 Summary of the Invention [Problem to be solved by the invention]

[0004] Metal members whose surfaces have been roughened by the method described in Patent Document 1 have a nanometer-order uneven structure on their surfaces, which allows them to exhibit excellent bonding strength to, for example, resin members. On the other hand, metal members whose surfaces have been roughened by the method described in Patent Document 1 have the problem that the nanometer-order uneven structure formed on the surface disappears over time. This is thought to be because metal hydroxides, which are produced when the surface of the metal member reacts with moisture in the air, fill in the nanometer-order uneven structure.

[0005] In view of the above circumstances, an object of one embodiment of the present disclosure is to provide a metal member whose surface uneven structure is maintained for a long period of time, a metal-resin joined body using this metal member, and a method for manufacturing the metal member. [Means for solving the problem]

[0006] The means for solving the above problems include the following embodiments. <1> having a surface with a concave-convex structure, A metal member, the surface of which is coated with a hydrophobic film. <2> having a surface with a concave-convex structure, The metal member has a surface with a water contact angle of 90° or more. <3> having a surface with a concave-convex structure, A metal member having a surface to which an organic compound is chemically bonded. <4> The organic compound has a polar group. <3> The metal member according to claim 1. <5> The uneven structure includes a dendritic structure. <1> ~ <4> The metal member according to any one of the preceding claims. <6> The average thickness of the dendritic structure is 20 nm to 1000 nm. <5> The metal member according to claim 1. <7> The average value of the ten-point average roughness (Rzjis) of the surface is 2 μm to 50 μm. <1> ~ <4> The metal member according to any one of the preceding claims. <8> The average value of the average length (RSm) of the roughness curve element of the surface is 10 μm to 400 μm. <1> ~ <4> The metal member according to any one of the preceding claims. <9> Contains aluminum, <1> ~ <4> The metal member according to any one of the preceding claims. <10> <1> ~ <4> 10. A metal resin bonded body comprising the metal member according to any one of claims 1 to 9, and a resin member bonded to the surface of the metal member having the concave-convex structure. <11> forming a textured structure on the surface of a metal member; and applying an organic compound to the surface on which the uneven structure is formed. <12> The organic compound has an alkyl group having 1 to 20 carbon atoms. <11> The method for manufacturing the metal member according to claim 1. <13> The organic compound has a polar group. <11> The method for manufacturing the metal member according to claim 1. [Effects of the Invention]

[0007] According to one embodiment of the present disclosure, there are provided a metal member in which the surface uneven structure is maintained for a long period of time, a metal-resin joined body using this metal member, and a method for manufacturing a metal member. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an electron microscope image showing the results of a high-temperature, high-humidity storage test carried out in Example 1. [Figure 2] 1 is an electron microscope image showing the results of a high-temperature, high-humidity storage test carried out in Example 2. [Figure 3] 10 is an electron microscope image showing the results of a high-temperature, high-humidity storage test carried out in Example 3. [Figure 4] 10 is an electron microscope image showing the results of a high-temperature, high-humidity storage test carried out in Example 4.

[0009] In the present disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced by the upper or lower limit value of another numerical range described in stages, or may be replaced by a value shown in an example. In this disclosure, when a material contains multiple substances corresponding to each component, the amount of each component in the material means the total amount of the multiple substances present in the material unless otherwise specified.

[0010] <Metal Member (First Embodiment)> A first embodiment of a metal member of the present disclosure is a metal member having a surface with an uneven structure, the surface being coated with a hydrophobic film.

[0011] The metal member of this embodiment maintains the surface unevenness even long after the surface roughening treatment, which is thought to be because the hydrophobic film covering the surface of the metal member prevents the surface of the metal member from coming into contact with moisture in the air, thereby suppressing the generation of metal hydroxide on the surface of the metal member.

[0012] There are no particular limitations on the components contained in the hydrophobic film, the method for forming the hydrophobic film, etc. The hydrophobic film preferably has a water contact angle of 90° or more, more preferably 100° or more, and even more preferably 110° or more. The water contact angle in the present disclosure is measured by the method described in the Examples section below.

[0013] From the viewpoint of the strength of the hydrophobic film, it is preferable that the hydrophobic film be formed from an organic compound. From the viewpoint of forming a coating while minimizing the effect on the uneven surface structure of the metal member, the molecular weight of the organic compound is preferably 1,000 or less, more preferably 500 or less, and even more preferably 300 or less.

[0014] The organic compound preferably has a hydrophobic functional group such as a hydrocarbon group. The hydrocarbon group of the organic compound may be either linear or cyclic. Examples of linear hydrocarbon groups include alkyl groups. The alkyl groups may contain double or triple bonds or may not contain double or triple bonds. Examples of cyclic hydrocarbon groups include aryl groups and cycloalkyl groups.

[0015] From the viewpoint of durability of a film formed from an organic compound, it is preferable that the organic compound is in a state of being chemically bonded to the surface of the metal member, i.e., it is preferable to coat the surface of the metal member with an organic compound that can be chemically bonded to the surface of the metal member.

[0016] The type of organic compound that chemically bonds with the surface of the metal member is not particularly limited and can be selected depending on the surface material of the metal member. For example, if hydroxyl groups are present on the surface of the metal member, an organic compound having a functional group that reacts with the hydroxyl groups can be selected. Examples of such organic compounds include compounds having an alkyl group with 1 to 20 carbon atoms and a functional group that reacts with the hydroxyl groups.

[0017] Specific examples of organic compounds that chemically bond with the surface of a metal member include phosphonic acid compounds, silane compounds, carboxylic acid derivatives, fluorohydrocarbons, and thiol derivatives. Specific examples of compounds having an alkyl group with 1 to 20 carbon atoms that chemically bond with the surface of a metal component include phosphonic acid compounds having an alkyl group with 1 to 20 carbon atoms, silane compounds having an alkyl group with 1 to 20 carbon atoms, carboxylic acid derivatives, fluorohydrocarbons, and thiol derivatives.

[0018] The organic compound may be a compound having an alkyl group having 1 to 20 carbon atoms. In a compound having an alkyl group having 1 to 20 carbon atoms, the number of carbon atoms in the alkyl group of the compound is not particularly limited as long as it is within the range of 1 to 20. The number of carbon atoms in the alkyl group may be 3 or more, 5 or more, 10 or more, or 15 or more. The number of carbon atoms in the alkyl group may be 18 or less, 15 or less, or 12 or less.

[0019] The number of carbon atoms in the alkyl group may be selected depending on the type of resin member to be bonded to the metal member. For example, when the resin member to be bonded to the metal member contains a polar group (e.g., an amide group in polyamide), the number of carbon atoms in the alkyl group may be 12 or less, 10 or less, or 5 or less. By reducing the number of carbon atoms in the alkyl group, the distance between the surface of the metal member and the resin member can be shortened. As a result, while contact between the surface of the metal member and moisture in the air is suppressed, an interaction between the surface of the metal member and the resin member is effectively expressed, and good bonding strength may be obtained.

[0020] The alkyl group having 1 to 20 carbon atoms may be unsubstituted or may have a substituent, and is preferably unsubstituted. The alkyl group having 1 to 20 carbon atoms may be linear or branched, and is preferably linear. The compound having an alkyl group having 1 to 20 carbon atoms may have one or more alkyl groups, and preferably has one alkyl group.

[0021] The organic compound is preferably capable of forming a self-assembled monolayer on the surface of the metal member. The self-assembled monolayer is extremely thin, about 1 to 2 nanometers thick. Therefore, the hydrophobic film formed on the surface of the metal component has little effect on the nanometer-order uneven structure.

[0022] Specific examples of organic compounds capable of forming a self-assembled monolayer on the roughened surface of an antibacterial member include phosphonic acid compounds having a hydrocarbon group and silane compounds having a hydrocarbon group. The hydrocarbon group is preferably a chain hydrocarbon group, and more preferably an alkyl group. Specific examples of compounds having an alkyl group with 1 to 20 carbon atoms that can form a self-assembled monolayer on the surface of a metal member include phosphonic acid compounds having an alkyl group with 1 to 20 carbon atoms and silane compounds having an alkyl group with 1 to 20 carbon atoms. From the viewpoint of the stability of the formed self-assembled monolayer, phosphonic acid compounds having an alkyl group with 1 to 20 carbon atoms are preferred.

[0023] Phosphonic acid compounds form a denser self-assembled monolayer than silane compounds. For example, silane compounds react only with hydroxyl groups (OH) present on the surface of metal components, whereas phosphonic acid compounds react only with protons (H + ) is supplied to the film, which regenerates OH and initiates a chain reaction. Therefore, it is believed that the film formed using the phosphonic acid compound has excellent stability.

[0024] The organic compound may have a polar group. If the organic compound has a polar group, for example, good bonding strength may be obtained when a resin member containing a polar group is bonded to a metal member. The polar group that the organic compound may have means a polar group other than the functional group for chemically bonding the compound to the surface of the metal member.

[0025] Specific examples of the polar group include an amino group, a carboxy group, a hydroxy group, a sulfo group, a sulfonimide group, a sulfate group, a phosphonic acid group, a phosphate group, an amino group, an ammonium group, an epoxy group, and a thiol group. When the organic compound has a polar group, the position of the polar group is not particularly limited. For example, when the organic compound has a hydrocarbon group, the polar group may be bonded to the hydrocarbon group or may be bonded to the terminal of the hydrocarbon group. When the organic compound has a polar group and a functional group for chemically bonding the organic compound to the surface of a metal member, the positions of the polar group and the functional group are not particularly limited. For example, when the organic compound has a hydrocarbon group, the polar group and the functional group may be bonded to different positions of the hydrocarbon group, or the polar group and the functional group may be bonded to both ends of the hydrocarbon group, respectively.

[0026] When the organic compound has polar groups, the number of polar groups is not particularly limited. For example, the number of polar groups may be 1 to 3, or may be 1 or 2, or may be 1. When the organic compound has two or more polar groups, the two or more polar groups may be the same type or different types.

[0027] The method for applying the organic compound to the surface of the metal member is not particularly limited, and specific examples of the application method include a method of applying a liquid in which the carbon-organic compound is dissolved or dispersed to the surface of the metal member, and a method of immersing the metal member in the liquid.

[0028] After the organic compound is applied to the surface of the metal member, a heat treatment may be performed, which can promote, for example, chemical bonding between the organic compound and the surface of the metal member.

[0029] The material of the metal member is not particularly limited, and specific examples of the material of the metal member include metals selected from iron, copper, nickel, gold, silver, platinum, cobalt, zinc, lead, tin, titanium, chromium, aluminum, magnesium, and manganese, and alloys containing at least one selected from the above metals.

[0030] The surface of the metal member of this embodiment is coated with a hydrophobic film, so that the uneven structure is maintained well for a long period of time even if the metal member is made of a material such as aluminum that reacts with moisture in the air to produce metal hydroxide on the surface.

[0031] The metal member may be made of one type of material or two or more types of material. The metal member may have a main body and a plating layer formed on the surface of the main body.

[0032] The uneven structure on the surface of the metal member may include a dendritic structure. In the present disclosure, the term "dendritic structure" refers to a structure in which a plurality of branched trunks stand tall on the surface of a metal component. The dendritic structure is composed of, for example, a trunk (main trunk) rising from the surface of the metal component, branches (main branches) branching off from the main trunk, and branches (side branches) branching off from the main branches. Whether or not a dendritic structure is formed on the surface of a metal member can be determined by observing the cross-sectional profile of the metal member using, for example, a scanning electron microscope (SEM).

[0033] The average density of the main trunk of the dendritic structure is preferably 5 fibers / μm or more, more preferably 7 fibers / μm or more, and even more preferably 10 fibers / μm or more. The average density of the main trunk of the dendritic structure is preferably 40 fibers / μm or less, more preferably 35 fibers / μm or less, and even more preferably 30 fibers / μm or less. The average number density of the main trunk of the dendritic structure is calculated from the cross-sectional profile of the metal part by scanning electron microscopy (SEM). Specifically, it is the arithmetic mean value of values ​​measured at any 10 points.

[0034] The average thickness of the dendritic structure is preferably 20 nm to 1000 nm, more preferably 30 nm to 900 nm, and even more preferably 50 nm or more and 800 nm or less. The average thickness of the dendritic structure is calculated from the cross-sectional profile of the metal member taken by a scanning electron microscope (SEM). Specifically, it is the arithmetic mean value of values ​​measured at any 10 points in the cross-sectional profile of the metal member having a surface texture.

[0035] It is preferable that the surface of the metal component satisfies at least one of the following (1) and (2): When the surface of the metal component satisfies at least one of (1) and (2), it can be determined that a micrometer-order uneven structure is formed on the surface of the metal component.

[0036] (1) The average value of the ten-point average roughness (Rzjis) is 2 μm to 50 μm. (2) The average value of the mean length of the roughness profile element (RSm) is 10 μm to 400 μm.

[0037] In the present disclosure, the ten-point average roughness (Rzjis) of the surface of a metal member is measured in accordance with JIS B0601:2001 (corresponding international standard: ISO4287). In the present disclosure, the mean length of the roughness profile element (RSm) of the surface of a metal member is measured in accordance with JIS B0601:2001 (corresponding international standard: ISO4287).

[0038] The average value of the ten-point average roughness (Rzjis) on the surface of the metal member is preferably in the range of 5 μm to 30 μm, more preferably 8 μm to 25 μm, and even more preferably 10 μm to 20 μm. The average value of the ten-point average roughness (Rzjis) on the surface of a metal member is the arithmetic mean value of values ​​measured at any 10 points on the surface of the metal member having an uneven structure.

[0039] The average value of the mean length of the roughness curve elements (RSm) on the surface of the metal member is preferably in the range of 50 μm to 350 μm, more preferably 70 μm to 330 μm, even more preferably 70 μm to 250 μm, and even more preferably 70 μm to 230 μm. The average value of the mean length of the roughness profile elements (RSm) on the surface of a metal member is the arithmetic mean value of values ​​measured at any 10 points on the surface of the metal member having an uneven structure.

[0040] The surface of the metal member preferably satisfies at least one of the above (1) and (2) and includes a dendritic structure. The surface of a metal component satisfies at least one of the above (1) and (2) and contains a dendritic structure, which means that the surface of the metal component has a micrometer-order uneven structure (base rough surface) formed thereon, and further has a nanometer-order uneven structure (fine rough surface) formed on that surface (double rough surface). When the surface of the metal member is in a double roughened state, for example, excellent bonding strength of the metal member to the resin member can be obtained.

[0041] The average pore size of the recesses in the uneven structure on the surface of the metal member may be, for example, 5 nm to 250 μm, preferably 10 nm to 150 μm, and more preferably 15 nm to 100 μm. The average pore depth of the recesses in the uneven structure on the surface of the metal member may be, for example, 5 nm to 250 μm, preferably 10 nm to 150 μm, and more preferably 15 nm to 100 μm. When either or both of the average pore diameter and the average pore depth of the recesses in the uneven structure on the surface of the metal member are within the above numerical ranges, stronger bonding tends to be obtained.

[0042] The average pore size and average pore depth of the recesses in the concave-convex structure can be determined using an electron microscope or a laser microscope. Specifically, the surface and cross section of the surface of the metal member are photographed. From the photographs obtained, 50 recesses are arbitrarily selected, and the average pore size and average pore depth of the recesses can be calculated as arithmetic mean values ​​from the pore size and pore depth of the recesses.

[0043] A metal member having a surface with an uneven structure can be obtained, for example, by performing a roughening treatment on the surface of the metal member. Examples of roughening treatment methods for metal members include a laser method as disclosed in Japanese Patent No. 4020957; a method of immersing the surface of a metal member in an aqueous solution of an inorganic base such as NaOH or an inorganic acid such as HCl or HNO3; a method of treating the surface of a metal member by anodic oxidation as disclosed in Japanese Patent No. 4541153; a displacement crystallization method in which etching is performed with an acid-based etching solution containing an acid-based etching agent (preferably an inorganic acid, ferric ions, or cupric ions) and, if necessary, manganese ions, aluminum chloride hexahydrate, sodium chloride, etc. as disclosed in International Publication No. 2015-8847; a method of immersing the surface of a metal member in an aqueous solution of one or more selected from hydrazine hydrate, ammonia, and water-soluble amine compounds (NMT method) as disclosed in International Publication No. 2009 / 31632; a hot water treatment method as disclosed in Japanese Patent Laid-Open No. 2008-162115; and roughening treatments such as blasting.

[0044] The roughening treatment of the metal member may be a treatment in which a porous plating layer is formed on the surface of the metal member as described in Japanese Patent No. 5366076.

[0045] Among the above methods, treatment with an acid etching agent is preferred from the viewpoint of increasing the bonding strength of the metal member to the resin member. The treatment with an acid-based etching agent may be, for example, a method in which the following steps (1) to (4) are carried out in this order.

[0046] (1) Pretreatment process A pretreatment is performed to remove oxide films and hydroxide films present on the surface of the metal component. This is usually done by mechanical polishing or chemical polishing. If the surface of the metal component is heavily contaminated with machine oil or the like, it may be treated with an alkaline aqueous solution such as a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, or degreased.

[0047] (2) Treatment with alkaline aqueous solution containing zinc ions Alkali hydroxide (MOH) and zinc ion (Zn 2+ ) and the mass ratio (MOH / Zn2+ The pretreated metal member is immersed in an aqueous alkaline solution containing zinc ions, the aqueous solution containing zinc ions in a ratio of 1 to 100. In the MOH, M is an alkali metal or alkaline earth metal.

[0048] (3) Treatment process using acid etching agent After step (2), the metal member is treated with an acid-based etching agent containing at least one of ferric ions and cupric ions and an acid, thereby dissolving the zinc-containing coating on the surface of the metal member and forming a micrometer-order fine uneven shape.

[0049] (4) Post-processing After the step (3), the metal member is washed. This usually involves rinsing with water and drying. Ultrasonic washing may also be included to remove smut.

[0050] The roughening treatment of the metal member may be carried out two or more times. For example, the above steps (1) to (4) may be carried out to form a micrometer-order uneven structure (base rough surface) on the surface of the metal member, and then a nanometer-order uneven structure (fine rough surface) may be formed.

[0051] As a method for forming a fine roughened surface after forming a base roughened surface on the surface of a metal member, for example, a metal member on which a base roughened surface has been formed is subjected to a standard electrode potential E 0 An example of such a method is to contact the material with an oxidizing acidic aqueous solution containing a metal cation having a pH of more than -0.2 and not more than 0.8, preferably more than 0 and not more than 0.5. The oxidizing acidic aqueous solution is 0 It is preferable that the metal cations contained therein do not have a value of -0.2 or less. Standard electrode potential E at 25°C 0 The metal cations for which the value is greater than -0.2 and less than 0.8 are Pb 2+ , Sn 2+ , Ag + , Hg 2+ , Cu 2+Among these, Cu is the most popular from the viewpoint of the scarcity of metals and the safety and toxicity of the corresponding metal salts. 2+ is preferred. Cu 2+ Examples of compounds that generate this include inorganic compounds such as copper hydroxide, cupric oxide, cupric chloride, cupric bromide, copper sulfate, and copper nitrate, and from the viewpoints of safety, toxicity, and efficiency in providing a dendritic layer, copper oxide is preferred.

[0052] Examples of the oxidizing acidic aqueous solution include nitric acid and an acid obtained by mixing nitric acid with hydrochloric acid, hydrofluoric acid, or sulfuric acid. Furthermore, an aqueous solution of a percarboxylic acid, such as peracetic acid or performic acid, may also be used. When nitric acid is used as the oxidizing acidic aqueous solution and cupric oxide is used as the metal cation generating compound, the nitric acid concentration constituting the aqueous solution is, for example, 10% to 40% by mass, preferably 15% to 38% by mass, and more preferably 20% to 35% by mass. Furthermore, the copper ion concentration constituting the aqueous solution is, for example, 1% to 15% by mass, preferably 2% to 12% by mass, and more preferably 2% to 8% by mass.

[0053] The temperature at which the metal member having a roughened base surface is brought into contact with the oxidizing acidic aqueous solution is not particularly limited, but in order to complete the roughening at an economical speed while controlling the exothermic reaction, a treatment temperature of, for example, room temperature to 60° C., preferably 30° C. to 50° C. is used. The treatment time is, for example, in the range of 1 to 15 minutes, preferably 2 to 10 minutes.

[0054] <Metal Member (Second Embodiment)> A second embodiment of the metal member of the present disclosure is having a surface with a concave-convex structure, The surface is a metal member having a water contact angle of 90° or more.

[0055] The metal component of this embodiment maintains the surface uneven structure well even long after the surface roughening treatment, which is thought to be because the contact angle of water on the surface of the metal component of 90° or more prevents the surface of the metal component from coming into contact with moisture in the air, thereby suppressing the generation of metal hydroxide on the surface of the metal component.

[0056] From the viewpoint of maintaining a good textured structure on the surface of the metal member, the contact angle of water on the surface of the metal member is preferably 100° or more, and more preferably 110° or more.

[0057] There are no particular limitations on the method for making the contact angle of water on the surface of the metal member equal to or greater than 90°. For example, a compound having a hydrophobic functional group such as a hydrocarbon group may be chemically bonded to the surface of the metal member. Details of the compound having a hydrocarbon group are as described for the metal member of the first embodiment.

[0058] <Metal Member (Third Embodiment)> A third embodiment of the metal member is having a surface with a concave-convex structure, The surface is a metal member to which an organic compound is chemically bonded.

[0059] The metal member of this embodiment maintains the surface uneven structure well even after a long time has passed since the surface roughening treatment. This is thought to be because the organic compound chemically bonded to the surface of the metal member prevents the surface of the metal member from coming into contact with moisture in the air, thereby suppressing the generation of metal hydroxide on the surface of the metal member.

[0060] The details and preferred aspects of the organic compound are the same as those of the organic compound described in relation to the metal member of the first embodiment.

[0061] The surface to which the organic compound is chemically bonded may be hydrophobic or hydrophilic. An example of a case where the surface to which an organic compound is chemically bonded is hydrophobic is when the organic compound chemically bonded to the surface of a metal component has a hydrophobic functional group such as a hydrocarbon group. An example of a case where the surface to which an organic compound is chemically bonded is hydrophilic is when the organic compound chemically bonded to the surface of a metal member has a hydrophilic functional group such as a polar group. When the surface to which the organic compound is chemically bonded is hydrophilic, the organic compound preferably contains a hydrophilic functional group (e.g., the polar group described above) and a hydrophobic functional group (e.g., the hydrocarbon group described above). When the organic compound chemically bonded to the surface of the metal component contains a hydrophobic functional group, the hydrophobic functional group is disposed on the surface of the metal component. As a result, even if the surface to which the organic compound is chemically bonded is hydrophilic, contact between the surface of the metal component and the external environment can be effectively suppressed.

[0062] <Metal-resin bonded body> The metal-resin joined body of the present disclosure comprises: The metal member described above; and a resin member bonded to the surface of the metal member having the concave-convex structure.

[0063] In the present disclosure, the state in which a metal member and a resin member are "joined" means a state in which the metal member is fixed to the resin member without using adhesive, screws, or the like.

[0064] The state in which the metal member is bonded to the resin member can be achieved, for example, by applying the material of the resin member, which has fluidity due to melting or softening, to the uneven surface of the metal member. When the material of the resin member has fluidity, the material of the resin member penetrates into the uneven surface of the metal member, producing an anchor effect, and the resin member is firmly bonded to the surface of the metal member.

[0065] The type of resin contained in the resin member is not particularly limited, and may be a thermoplastic resin, a thermosetting resin, a thermoplastic elastomer, a thermosetting elastomer, or the like. Examples of thermoplastic resins include polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile / styrene resin (AS), acrylonitrile / butadiene / styrene resin (ABS), methacrylic resin (PMMA), polyvinyl chloride (PVC), polyamide (PA), polyacetal (POM), ultra-high molecular weight polyethylene (UHPE), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polymethylpentene (TPX), polycarbonate (PC), modified polyphenylene ether (PPE), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), liquid crystal resin (LCP), polytetrafluoroethylene (PTFE), polyetherimide (PEI), polyarylate (PAR), polysulfone (PSF), polyethersulfone (PES), and polyamideimide (PAI). Examples of the thermosetting resin include phenol resin, urea resin, melamine resin, unsaturated polyester, alkyd resin, epoxy resin, and diallyl phthalate. Examples of the thermoplastic elastomer include styrene-based thermoplastic elastomers, polyester-based thermoplastic elastomers, urethane-based thermoplastic elastomers, and amide-based thermoplastic elastomers. Thermosetting elastomers include diene rubbers such as natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), chloroprene rubber (CR), and acrylonitrile-butadiene copolymer rubber (NBR), as well as non-diene rubbers such as butyl rubber (IIR), ethylene-propylene rubber (EPM), urethane rubber, silicone rubber, and acrylic rubber. The resin contained in the resin member may be in the form of an ionomer or a polymer alloy. The resin member may contain only one type of resin or two or more types of resin.

[0066] The resin member may contain various additives in addition to the resin, such as fillers such as glass fiber, carbon fiber, and inorganic powder, heat stabilizers, antioxidants, pigments, weathering agents, flame retardants, plasticizers, dispersants, lubricants, release agents, and antistatic agents.

[0067] When the resin member contains components other than resin, the proportion of resin in the entire resin member is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more.

[0068] The step of joining the resin member to the surface of the metal member having the concave-convex structure can be carried out by a known method such as injection molding.

[0069] <Metal component manufacturing method> The method for manufacturing a metal member according to the present disclosure includes: forming a textured structure on the surface of a metal member; and applying an organic compound to the surface on which the uneven structure is formed. In the above method, the organic compound may be replaced with a hydrophobizing agent, which means a substance capable of hydrophobizing the surface on which the textured structure is formed.

[0070] The metal member produced by the above method maintains the uneven structure well even after a long time has passed since the unevenness was formed on the surface of the metal member. This is thought to be because the organic compound applied to the uneven surface of the metal member prevents the surface of the metal member from coming into contact with moisture in the air, thereby suppressing the generation of metal hydroxide on the surface of the metal member.

[0071] In the above method, the method for forming the uneven structure on the surface of the metal member is not particularly limited, and can be selected from, for example, the methods exemplified above for the metal member.

[0072] In the above method, the method for applying the organic compound to the surface of the metal member on which the concavo-convex structure is formed is not particularly limited, and examples thereof include a method of applying a liquid in which the organic compound is dissolved or dispersed to the surface of the metal member, and a method of immersing the metal member in the liquid.

[0073] The details and preferred aspects of the organic compound used in the above method are the same as those of the organic compound described for the metal member of the first embodiment.

[0074] After the organic compound is applied to the surface of the metal member, a heat treatment may be performed, which can promote, for example, chemical bonding between the organic compound and the surface of the metal member. [Example]

[0075] Hereinafter, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to the descriptions of these examples.

[0076] Example 1 (1) Surface treatment of aluminum alloy plates An acid-based etching agent was used to form a micrometer-order uneven structure on an aluminum alloy (A3003) plate, and then a roughening treatment was performed to form a nanometer-order uneven structure (i.e., to satisfy the above (1) and (2) and to create a state in which a dendritic structure is included).

[0077] The roughened aluminum alloy plate was immersed in an ethanol solution (5 mmol / L) of n-octadecylphosphonic acid for 1 minute, then washed with ethanol and dried at 80°C for 20 minutes.

[0078] Ion-exchanged water (2 μL) was dropped onto the surface of an aluminum alloy plate treated with n-octadecylphosphonic acid, and the contact angle was measured 1 minute after the drop. The measurement was carried out under conditions of 24°C and 31% relative humidity. The contact angle calculated using the tangent method from an image of the water droplet taken with a digital camera was 119°.

[0079] (2) High temperature and humidity storage test An aluminum alloy plate treated with n-octadecylphosphonic acid was stored at 40°C and 90% relative humidity, and electron microscope images of the surface of the aluminum alloy plate were taken at the start of the test (initial stage), one week, one month, and two months later. The images are shown in Figure 1. For comparison, an aluminum alloy plate not treated with n-octadecylphosphonic acid was stored at 40°C and 90% relative humidity, and electron microscope images of the surface of the aluminum alloy plate were taken at the start of the test (initial stage), one week, one month, two months, and one year. The images obtained are shown in Figure 1.

[0080] As shown in Figure 1, the fine uneven structure of the aluminum alloy plate not treated with n-octadecylphosphonic acid disappeared over time, whereas the fine uneven structure of the aluminum alloy plate treated with n-octadecylphosphonic acid was observed even after a long time had passed since the start of the test.

[0081] (3) Resin bonding test An aluminum alloy plate treated with n-octadecylphosphonic acid was placed in an insert molding die, and molten polypropylene (PP) was injected into the aluminum alloy plate to bond the PP to the textured surface. Five test specimens were fabricated. The shear bond strength of the test specimens was measured using an autograph (AGS-500-D, TYPE-III, Shimadzu Corporation). The arithmetic mean value of the five test specimens was 28 MPa. For comparison, a test piece was similarly prepared using an aluminum alloy plate that had not been treated with n-octadecylphosphonic acid, and the shear bond strength was measured, finding a value of 29 MPa. From the above results, it was found that the effect of treatment with n-octadecylphosphonic acid on the bonding strength of aluminum alloy (A3003) to PP was small.

[0082] <Example 2> (1) Surface treatment of aluminum alloy plates Except for using a plate made of an aluminum alloy (A6063) as the aluminum alloy plate, the roughening treatment and the treatment with n-octadecylphosphonic acid were carried out in the same manner as in Example 1. The contact angle of ion-exchanged water on the surface of the treated aluminum alloy plate, measured in the same manner as in Example 1, was 120°.

[0083] (2) High temperature and humidity storage test An aluminum alloy plate treated with n-octadecylphosphonic acid was stored at 40°C and 90% relative humidity, and electron microscope images of the surface of the test piece were taken at the start of the test (initial stage), one week, one month, and two months later. The images obtained are shown in Figure 2. For comparison, an aluminum alloy plate not treated with n-octadecylphosphonic acid was stored at 40°C and a relative humidity of 90%, and electron microscope images of the surface of the test piece were taken at the start of the test (initial stage), one week, one month, and two months later. The images obtained are shown in Figure 2.

[0084] As shown in Figure 2, the fine uneven structure of the aluminum alloy plate not treated with n-octadecylphosphonic acid disappeared over time, whereas the fine uneven structure of the aluminum alloy plate treated with n-octadecylphosphonic acid was observed even after a long time had passed since the start of the test.

[0085] (3) Resin bonding test An aluminum alloy plate treated with n-octadecylphosphonic acid was placed in an insert molding die, and molten polypropylene (PP) was injected into the aluminum alloy plate to bond the PP to the textured surface. Five test specimens were fabricated. The shear bond strength of the test specimens was measured using an autograph (AGS-500-D, Type III, Shimadzu Corporation). The arithmetic mean value of the five test specimens was 29 MPa. For comparison, a test piece was similarly prepared using an aluminum alloy plate that had not been treated with n-octadecylphosphonic acid, and the shear bond strength was measured, finding a value of 29 MPa. From the above results, it was found that the effect of treatment with n-octadecylphosphonic acid on the bonding strength of aluminum alloy (A6063) to PP was small.

[0086] A test piece was prepared in the same manner as above except that PP was replaced with polyphenylene sulfide (PPS), and the shear bond strength of the test piece was measured and found to be 42 MPa. For comparison, a test piece was similarly prepared using an aluminum alloy plate that had not been treated with n-octadecylphosphonic acid, and the shear bond strength was measured, finding a value of 43 MPa. From the above results, it was found that the effect of treatment with n-octadecylphosphonic acid on the bonding strength of aluminum alloy (A6063) to PPS was small.

[0087] Example 3 (1) Surface treatment of aluminum alloy plates Except for using a plate made of an aluminum alloy (A6061) as the aluminum alloy plate, the roughening treatment and the treatment with n-octadecylphosphonic acid were carried out in the same manner as in Example 1. The contact angle of ion-exchanged water on the surface of the treated aluminum alloy plate, measured in the same manner as in Example 1, was 115°.

[0088] (2) High temperature and humidity storage test An aluminum alloy plate treated with n-octadecylphosphonic acid was stored at 40°C and 90% relative humidity, and electron microscope images of the surface of the test piece were taken at the start of the test (initial stage), one week, one month, and two months later. The images obtained are shown in Figure 3. For comparison, an aluminum alloy plate not treated with n-octadecylphosphonic acid was stored at 40°C and a relative humidity of 90%, and electron microscope images of the surface of the test piece were taken at the start of the test (initial stage), one week, one month, and two months later. The images obtained are shown in Figure 3.

[0089] As shown in Figure 2, the fine uneven structure of the aluminum alloy plate not treated with n-octadecylphosphonic acid disappeared over time, whereas the fine uneven structure of the aluminum alloy plate treated with n-octadecylphosphonic acid was observed even after a long time had passed since the start of the test.

[0090] (3) Resin bonding test An aluminum alloy plate treated with n-octadecylphosphonic acid was placed in an insert molding die, and molten polypropylene (PP) was injected into the aluminum alloy plate to bond the PP to the textured surface. Five test specimens were fabricated. The shear bond strength of the test specimens was measured using an autograph (AGS-500-D, Type III, Shimadzu Corporation). The arithmetic mean value of the five test specimens was 26 MPa. For comparison, a test piece was similarly prepared using an aluminum alloy plate that had not been treated with n-octadecylphosphonic acid, and the shear bond strength was measured, finding a value of 28 MPa. From the above results, it was found that the effect of treatment with n-octadecylphosphonic acid on the bonding strength of aluminum alloy (A6061) to PP was small.

[0091] Example 4 (1) Surface treatment of aluminum alloy plates A plate made of an aluminum alloy (A3003) was subjected to a roughening treatment in the same manner as in Example 1. The aluminum alloy plate after the roughening treatment was immersed for 1 minute in an ethanol solution (5 mmol / L) of hydrophobizing agents 1 to 5 shown below. Thereafter, the aluminum alloy plate was washed with ethanol and dried at 80°C for 20 minutes, and the contact angle of ion-exchanged water was measured in the same manner as in Example 1. The results are shown in Table 1.

[0092] Organic Compound 1: Propylphosphonic Acid Organic Compound 2: Undecylphosphonic Acid Organic Compound 3: 10-Carboxydecylphosphonic Acid Organic Compound 4: 11-Hydroxyundecylphosphonic Acid Organic Compound 5: 11-Aminoundecylphosphonic Acid

[0093] (2) High temperature and humidity storage test Aluminum alloy sheets treated with organic compounds 1 to 5 were stored at 40°C and 90% relative humidity, and electron microscope images of the surfaces of the aluminum alloy sheets were taken one week, two months, and three months after the start of the test. The images are shown in Figure 4.

[0094] As shown in FIG. 4, the aluminum alloy plates treated with organic compounds 1 to 5 had a fine uneven structure even after a long time had passed since the start of the test.

[0095] (3) Resin bonding test The aluminum alloy plates treated with organic compounds 1 to 5 were placed in an insert molding die, and molten polyphthalamide (PPA) was injected into them to prepare five test specimens with the PPA bonded to the textured surface of the aluminum alloy plate. The shear bond strength of the test specimens was measured using an autograph (AGS-500-D, TYPE-III, Shimadzu Corporation). The arithmetic mean values ​​of the measurements for the five test specimens are shown in Table 1. For comparison, test pieces were prepared in the same manner using aluminum alloy plates that had not been treated with organic compounds, and the shear bond strength was measured. The results are shown in Table 1.

[0096] [Table 1]

[0097] The results shown in Table 1 indicate that the treatment with organic compounds 1 to 5 had little effect on the bonding strength of the aluminum alloy sheet to PPA. It was found that when organic compound 1, whose alkyl group has 3 carbon atoms, or organic compounds 3 to 5, which have polar groups, was used, the effect on the bonding strength of the aluminum alloy sheet to the PPA was smaller than when organic compound 2, whose alkyl group has 11 carbon atoms and no polar group, was used.

[0098] The disclosure of Japanese Patent Application No. 2022-025116 is incorporated herein by reference in its entirety. All publications, patent applications, and technical standards mentioned in this specification are incorporated by reference into this specification to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A metal member used in a metal-resin joined body including a metal member and a resin member joined to a surface of the metal member having an uneven structure, the metal member has a surface with an uneven structure, the surface has a water contact angle of 90° or more; The metal member has a surface to which a phosphonic acid compound having an alkyl group with three carbon atoms or a phosphonic acid compound having a polar group bonded to a hydrocarbon group is chemically bonded.

2. The metal member according to claim 1 , wherein the polar group is a carboxy group or a hydroxy group.

3. The metal member according to claim 1 , wherein the uneven structure includes a dendritic structure.

4. The metal member according to claim 3, wherein the average thickness of the dendritic structure is 20 nm to 1000 nm.

5. The metal member according to any one of claims 1 to 4, wherein the average value of the ten-point average roughness (Rzjis) of the surface is 2 µm to 50 µm.

6. The metal member according to any one of claims 1 to 4, wherein an average value of the average length (RSm) of the roughness curve elements of the surface is 10 µm to 400 µm.

7. The metal member according to any one of claims 1 to 4, comprising aluminum.

8. A metal-resin bonded body comprising the metal member according to any one of claims 1 to 4 and a resin member bonded to the surface of the metal member having the uneven structure.

9. A method for manufacturing a metal-resin bonded body, comprising a step of applying a resin member material in a fluid state due to melting or softening to a surface having an uneven structure of a metal member described in any one of claims 1 to 4 to form a resin member bonded to the metal member.

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