Surface-treated metal material and joint body

Abstract

Provided is a surface-treated metal material and a bonded body containing the same, for adhesive bonding, which can further improve adhesive durability. A surface-treated metal material in which a silane film is provided on at least a part of the surface of a metal substrate, wherein when a parallel polarized light having an incident angle of 75° is incident on the surface of the silane film, and an absorption spectrum is measured by Fourier transform infrared spectroscopy, an absorption peak is present in a wave number region of 1250 (cm －1 ) or more and 1150 (cm －1 ) or less, and when the surface roughness is measured for a 1 mm x 1 mm measurement range at any three positions on the surface of the silane film by a laser microscope, the aspect ratio is 0.5 or more.

Description

Technical Field

[0001] The present invention relates to surface-treated metal materials and joints containing the surface-treated metal materials. Background Technology

[0002] In the transportation equipment sector, including automobiles, ships, and aircraft, adhesive bonding is used as a joining technology between dissimilar materials such as steel and lightweight raw materials (aluminum alloys, titanium alloys, and carbon fiber) from a lightweight perspective. Furthermore, adhesive bonding is also gaining attention as a welding alternative to address field issues such as a shortage of welders, technology transfer, and improvements to the working environment, all from the perspective of increasing productivity and operability.

[0003] On the other hand, it is known that adhesive bonding has challenges in terms of strength reliability during long-term use. Compared to welding and bolting, it is more prone to strength reduction under combined stresses such as high temperature, high humidity, fatigue, or creep. In adhesive bonding, the adhesion between the adhesive and the bonded metal is crucial. If the adhesion between the metal surface and the adhesive is insufficient, water can penetrate to the metal-resin interface. This results in corrosion of the metal surface and peeling from the interface, thus significantly reducing the bond strength. Therefore, it is necessary to improve the adhesion between the metal and the adhesive resin to prevent water penetration into the bonding interface. Furthermore, the surface of the metal needs to be modified to a suitable bonding condition so that even if water penetration occurs, the metal surface is less likely to undergo changes in its condition.

[0004] To address the aforementioned issues, various surface treatment technologies have been proposed to date. For example, Patent Document 1 discloses an aqueous composition containing a tetraalkyl silicate or its monomeric or oligomeric hydrolysis product, and a hydrated oxide sol such as silica sol. By treating metallic materials such as aluminum, steel, or titanium with the above-mentioned aqueous composition, the initial adhesion and long-term stability of the coating film formed on it, such as adhesives, can be improved.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 10-510307 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, even when using the surface treatment technology described in Patent Document 1, the bond strength with the resin, such as the adhesive, decreases significantly after long-term wet deterioration testing. Therefore, the required bond durability cannot be obtained.

[0010] The present invention was made in view of the following problems, and its object is to provide a surface-treated metal material that has excellent bonding strength with resins such as adhesives and can further improve the bonding durability with resins, and a joint containing the surface-treated metal material.

[0011] Problem-solving methods

[0012] The above-mentioned objective of the present invention is achieved by the following [1] configuration of the surface-treated metal material.

[0013] [1] A surface-treated metal material, characterized in that it is a surface-treated metal material having a silane film formed on at least a portion of the surface of a metal substrate.

[0014] When parallel polarized light with an incident angle of 75° is incident on the surface of the silane film, and the absorption spectrum is measured by Fourier transform infrared spectroscopy, the absorption spectrum is observed at 1250 cm⁻¹. －1 ) and above and 1150 (cm) －1 Absorption peaks are found in the wavenumber region below 1000.

[0015] When measuring the surface roughness of the silane film using a laser microscope over a 1mm × 1mm measurement range at any three locations, the aspect ratio is greater than or equal to 0.5.

[0016] Furthermore, preferred embodiments of the present invention concerning surface-treated metallic materials relate to the following [2] and [3].

[0017] [2] The surface-treated metal material according to [1] is characterized in that an adhesive resin layer is present on the surface of the silane film.

[0018] [3] The surface-treated metal material according to [1] or [2] is characterized in that the absorbance of the absorption peak is 0.003 or higher.

[0019] The above-mentioned objective of the present invention is achieved by the following [4] and [5] configuration related to the joint.

[0020] [4] A joint, characterized in that it is a joint containing any one of the surface-treated metallic materials described in [1] to [3],

[0021] The first component and the second component are joined together via an adhesive resin layer.

[0022] Either the first component or the second component is the surface-treated metal material.

[0023] The silane film of the surface-treated metal material is bonded to the adhesive resin layer.

[0024] [5] A joint, characterized in that it is a joint containing any one of the surface-treated metallic materials described in [1] to [3],

[0025] The first component and the second component are joined together via an adhesive resin layer.

[0026] Both the first component and the second component are surface-treated metal materials having a metal substrate formed from the same or different metal materials.

[0027] The silane film of the first component and the silane film of the second component are bonded together by the adhesive resin layer.

[0028] The effects of the invention

[0029] According to the present invention, a surface-treated metal material is provided that exhibits excellent bonding strength with resins such as adhesives and further improves the bonding durability with resins, as well as a joint containing the surface-treated metal material. Attached Figure Description

[0030] Figure 1 It is a graph showing the absorption spectrum with absorbance on the vertical axis and wavenumber on the horizontal axis.

[0031] Figure 2A This is a side view showing the shape of the joint.

[0032] Figure 2B This is a top view showing the shape of the joint. Detailed Implementation

[0033] The inventors have conducted intensive research on metal materials that can improve the adhesion strength and durability with resins, even for difficult-to-bond metal materials such as stainless steel or titanium. Their findings indicate that the aforementioned problems can be solved by properly controlling the absorption spectrum and surface roughness of the silane film surface. The surface-treated metal materials according to embodiments of the present invention will be described in detail below.

[0034] [Surface-treated metallic materials]

[0035] The surface-treated metal material of this embodiment has a silane film formed on at least a portion of the surface of the metal substrate. The metal substrate and the silane film will be described in further detail below.

[0036] <Metal substrate>

[0037] As for the metal substrate, there are no particular limitations on the type and shape of any component formed of metal. Examples of metals include steel plates, various coated steel plates, pure aluminum or aluminum alloys, pure titanium or titanium alloys, stainless steel, copper or copper alloys, etc. In particular, for aluminum alloys, known alloys such as Al-Mg alloys, Al-Mg-Si alloys, Al-Zn-Mg alloys, Al-Si alloys, and Al-Cu alloys can be used. Similarly, for titanium alloys, known alloys such as α-titanium alloys, β-titanium alloys, and α+β-titanium alloys can be used. Furthermore, for stainless steel, known alloys such as austenitic stainless steels, ferritic stainless steels, martensitic stainless steels, and duplex stainless steels can be used.

[0038] <Silane film>

[0039] A silane film is disposed on at least a portion of the surface of the aforementioned substrate; specifically, it is a surface-treated film containing an organosilane compound. Because of its excellent adhesion to adhesives and superior corrosion resistance, the silane film containing the silane compound maintains excellent bonding strength when bonded to other components.

[0040] Silane films, for example, can be formed by coating an aqueous solution containing silicon oxide onto a substrate surface. The silicon oxide, activated by aqueous solution hydration, can self-polymerize via a sol-gel reaction. Furthermore, a substrate made of titanium or a titanium alloy has a naturally occurring oxide film. Therefore, by coating an aqueous solution of silicon oxide onto the oxide film on the substrate surface, the titanium oxide film reacts with the silicon oxide, and the silicon oxides also polymerize, thus forming a silane film with excellent adhesion to the substrate in a desired area on the substrate surface.

[0041] Furthermore, because the silane film has high miscibility with organic compounds such as machining oils, stamping oils, and adhesives, its bonding with adhesives is also excellent. In addition, even if machining oils such as machining oils and stamping oils adhere to the silane film, its influence can be mitigated, thus preventing the reduction in adhesion durability caused by oiling and achieving excellent corrosion resistance.

[0042] (Absorption spectrum obtained by Fourier transform infrared spectroscopy)

[0043] If a silane film is formed on the surface of a metal substrate, silicon-oxygen bonds will inevitably form in the region where the silane film is formed. In this embodiment, as an indicator of whether a silane film has indeed been formed, the following method is used: parallel polarized light with an incident angle of 75° is incident on the surface of the silane film, and the absorption spectrum is measured by Fourier transform infrared spectroscopy (FT-IR).

[0044] Figure 1 This is a graph showing the absorption spectrum with absorbance on the vertical axis and wavenumber on the horizontal axis. The silicon-oxygen bond at 1250 (cm²) －1 ) and above and 1150 (cm) －1 The wavenumber region below ) has Figure 1 The absorption peak is indicated by the middle arrow. Therefore, by observing whether there is an absorption peak in the above wavenumber region, it is possible to determine whether a silane film has formed.

[0045] Furthermore, if the absorbance of the absorption peak is 0.003 or higher, the presence or absence of a silane film can be determined more reliably. Therefore, an absorbance of 1250 (cm⁻¹) is preferred. －1 ) and above and 1150 (cm) －1 When there is an absorption peak in the wavenumber region below 0.003, the absorbance of the peak is above 0.003.

[0046] (Surface roughness)

[0047] If the surface shape of the metal substrate is uniformly rough, the metal treatment solution is uniformly maintained on the surface of the metal substrate during surface treatment to form a silane film. As a result, a silane film can be formed with a uniform film amount, resulting in a silane film with excellent performance. If the surface shape of the metal substrate is deviated, the metal treatment solution will remain in certain locations, such as deep trenches, where only the silane film in the trench portion becomes thick, thus failing to obtain a silane film with good performance. Furthermore, if a silane film with a uniform film thickness is formed, the stress applied to the interface can be uniformly distributed when the adhesive joint is subjected to stress. In this way, by reducing the force applied per unit area, the bond strength can be stabilized. Also, in this embodiment, the thickness of the silane film of the surface-treated metal material is several nm, so the surface shape of the metal substrate is also reflected on the surface of the surface-treated metal material. Therefore, in this embodiment, the surface roughness of the surface of the surface-treated metal material is specified.

[0048] The surface roughness of the surface-treated metallic material can be specified using the surface roughness standard defined in ISO 25178. In this embodiment, on the surface of the silane film, the surface roughness Str (aspect ratio of the surface texture) is measured using a laser microscope over a 1mm × 1mm measurement area at any three locations to determine whether a silane film with excellent performance has been formed. Str takes a value from 0 to 1. When Str is close to 0, it indicates texture or other irregularities, suggesting uneven surface roughness. On the other hand, when Str is close to 1, the surface shape is not dependent on orientation, indicating uniform roughness. Therefore, in this embodiment, it is preferable that Str is close to 1.

[0049] If the aspect ratio is less than 0.5, the deviation in the surface shape of the metal substrate becomes larger, and a silane film with uniform thickness cannot be formed, thus failing to obtain a silane film with excellent performance. Therefore, the aspect ratio obtained by the above measurement method is 0.5 or more, preferably 0.7 or more, and more preferably 0.8 or more.

[0050] As a method to achieve a uniformly rough surface on a surface-treated metallic material, one example is shot peening of a metallic substrate. Specifically, by selecting the type of blasting material, the aspect ratio Str can be adjusted.

[0051] The surface-treated metal material of this embodiment, configured as described above, has a silane film formed on at least a portion of the surface of the metal substrate, and the absorption spectrum and aspect ratio of the silane film are specified. Therefore, it possesses a silane film with excellent adhesion to the metal substrate and superior durability.

[0052] Furthermore, because the silane film exhibits high miscibility with machine oils such as processing oils and stamping oils, as well as organic compounds like adhesives, its bonding with adhesives is also excellent. Moreover, since the silane film can mitigate the effects of machine oils such as processing oils and stamping oils even when they adhere to it, it can prevent the reduction in adhesion durability caused by oiling, resulting in excellent corrosion resistance. Therefore, when the surface-treated metal material obtained by the manufacturing method of this embodiment is bonded to other components, it can maintain excellent bond strength for a long period.

[0053] <Adhesive Resin Layer>

[0054] The surface-treated metal material of this embodiment may also have an adhesive resin layer on the surface of the silane film. As described above, by having an adhesive resin layer on the surface of the silane film, which has excellent adhesion and durability to adhesives, the process of bonding the surface-treated metal material of this embodiment to other surface-treated metal materials or components can be simplified.

[0055] There is no particular limitation on the method of forming an adhesive resin layer on at least a portion of the surface of the silane film. For example, an adhesive sheet pre-made from an adhesive resin material can be pasted onto the surface of the silane film, or the adhesive resin material can be sprayed or coated onto the surface of the silane film.

[0056] In this invention, the resin constituting the adhesive resin layer is not particularly limited, and adhesive resins such as epoxy resins, polyurethane resins, nitrile resins, nylon resins, and acrylic resins, which have been used in bonding titanium or titanium alloy materials, can be used. Furthermore, the thickness of the adhesive resin layer is not particularly limited, but from the viewpoint of improving adhesive strength, it is preferably 10 to 500 μm, more preferably 50 to 400 μm.

[0057] [Manufacturing methods for surface-treated metallic materials]

[0058] The surface-treated metal material of this embodiment can be manufactured, for example, in the following manner.

[0059] <Shot peening process>

[0060] First, shot peening is performed on at least a portion of the surface of the metal substrate. Specifically, compressed air or an electric motor is used to propel abrasive particles or a solution containing abrasive particles at high speed into this area. This removes contaminants, deposits, and oxide films present on the surface of the metal substrate, purifying it, and creates an uneven surface area to adjust the aspect ratio.

[0061] (Types of shot peening)

[0062] There is no particular limitation on the type of shot peening process used in shot peening; both dry and wet shot peening methods can be used, and the same effect can be obtained regardless of the method used. For example, if dry shot peening is used, the equipment is small and versatile, making it preferable from an economic point of view. On the other hand, if wet shot peening is used, less heat is input to the surface of the metal substrate 1, and the residue of abrasive particles can be suppressed, making it preferable from the viewpoints of dust control and process stability. Furthermore, there is no particular limitation on the type of abrasive particles, and commercially available abrasive particles can be used.

[0063] <Coating Process>

[0064] Next, the surface area of ​​the metal substrate that has undergone the above-mentioned shot peening treatment is coated with a metal treatment solution containing a silane compound. In the coating process, the silane compound as the main component is applied in an appropriate amount to the surface of the metal substrate; methods include spraying, scrubbing, roller coating, brush coating, and immersion treatment. Specific examples of metal treatment solutions will be described later.

[0065] <Drying Process>

[0066] Subsequently, the solvent is evaporated from the metal treatment solution coated on the surface of the metal substrate, the metal substrate is dried, and the reaction between the silane compound and the oxide film, as well as the polymerization between the silane compounds, are promoted. Thus, a silane film can be formed on at least a portion of the surface of the metal substrate, producing a surface-treated metal material. The drying temperature is not particularly limited; for example, a temperature of around 50–100°C provides a good balance between productivity and energy consumption, and is therefore preferred. Furthermore, to improve the integrity of the silane film and maximize the adhesion between the substrate and the silane film, the steps of coating the substrate surface with the metal treatment solution and drying the substrate surface can be repeated 2–3 times.

[0067] <Adhesive resin layer formation process>

[0068] Preferably, the surface-treated metal material of this embodiment also has an adhesive resin layer on its surface. Specifically, after the drying process described above, an adhesive resin layer is formed on the surface of the silane film. As mentioned above, by forming an adhesive resin layer on the surface of the silane film, which has excellent adhesion to adhesives and durability, the process of bonding the surface-treated metal material to other surface-treated metal materials or other components can be simplified.

[0069] There are no particular limitations on the method for forming the adhesive resin layer. For example, an adhesive sheet pre-made from the adhesive resin material can be pasted onto the surface of the silane film, or the adhesive resin material can be sprayed or coated onto the surface of the silane film.

[0070] In this invention, the resin constituting the adhesive resin layer is not particularly limited, and adhesive resins such as epoxy resins, polyurethane resins, nitrile resins, nylon resins, and acrylic resins, which have been used in bonding titanium or titanium alloy materials, can be used. Furthermore, the thickness of the adhesive resin layer is not particularly limited, but from the viewpoint of improving adhesive strength, it is preferably 10 to 500 μm, more preferably 50 to 400 μm.

[0071] The following examples illustrate the metal processing solutions used to form silane films.

[0072] (Metal processing solution)

[0073] As a solution for metal treatment, a solution containing a silane compound is acceptable. For example, a solvent containing 50% to 99.99% by mass of water and 0% to 50% by mass of organic solvent can be used. More preferably, the mass of water relative to the total mass of the solution is 50% to 99.95% by mass. Furthermore, from the viewpoint of reducing volatile organic compounds (VOCs) and minimizing explosion hazards, it is preferable that the main component of the solvent is water. However, in order to reduce the surface tension of the solution for metal treatment, improve water wettability and coatability, and increase the drying speed, organic solvents such as those listed below may also be included.

[0074] When using organic solvents, various alcohols and polyethers can be used as organic solvents, such as methanol, ethanol, propanol, butanol (including isomers), ethylene glycol-based solvents and their ethers, as well as various water-soluble solvents.

[0075] The metal processing solution contains a silane compound at a concentration of 0.01% by mass or more and 1% by mass or less. Preferably, the silane compound contains an alkyl silicate ester or its oligomer, and a hydrolysate or polymer of an organosilane compound. More preferably, the concentration of the silane compound relative to the total mass of the metal processing solution is 0.05% by mass or more and 0.5% by mass or less. Furthermore, the concentration of the silane compound can be adjusted based on the amount of metal processing solution coated on the surface of the metal substrate. Specifically, as the silane compound included in the metal processing solution, it is preferable to use 0.005% by mass or more and less than 1% by mass of an alkyl silicate ester or its oligomer, and 0.005% by mass or more and less than 1% by mass of a hydrolysate or polymer of an organosilane compound.

[0076] If the aforementioned specific metal treatment solution is applied to at least a portion of the surface of a metal substrate, alkyl silicates or their oligomers are introduced into the surface of the substrate, forming a composite oxide film of metal and silicon constituting the metal substrate. Then, in a subsequent drying process, a silane film is formed from an organosilane compound chemically bonded to the composite oxide film. This results in a surface-treated metal material with excellent adhesion to adhesives, excellent corrosion resistance, and strong adhesion even when exposed to high-temperature and humid environments, exhibiting excellent adhesion durability. Furthermore, by using the aforementioned metal treatment solution, surface treatment with alkyl silicates or their oligomers and surface treatment with organosilane compounds can be performed in a single step, enabling the manufacture of surface-treated metal materials with excellent adhesion durability using a simplified process, thereby reducing equipment investment and manufacturing costs.

[0077] The pH of the metal treatment solution is preferably 2 or higher and 7 or lower. If the pH of the metal treatment solution is higher than 7, alkyl silicates or their oligomers are prone to overpolymerization, which may reduce the storage stability of the solution and is therefore not preferred. In addition, if the polymerization of alkyl silicates or their oligomers proceeds, the resulting film becomes thicker, and when stress is applied, it breaks down inside the silane film, making it impossible to obtain high adhesive strength. Therefore, the pH of the metal treatment solution is preferably 7 or lower, and from the viewpoint of the stability of alkyl silicates, it is more preferably 6 or lower.

[0078] On the other hand, if the pH of the metal treatment solution is lower than 2, the dissolution of the substrate surface intensifies, the silane film becomes uneven, and thus it is difficult to achieve stable adhesion. Therefore, the pH of the metal treatment solution is preferably 2 or higher, and more preferably 3 or higher considering the reactivity with the metal oxide film. Furthermore, the pH of the metal treatment solution can be appropriately adjusted by adding acids such as hydrochloric acid, sulfuric acid, nitric acid, and acetic acid.

[0079] The concentration of alkyl silicates or their oligomers in the metal treatment solution is preferably 0.005% by mass or more and less than 1% by mass. If the concentration of alkyl silicates or their oligomers in the metal treatment solution is 1% by mass or more, the resulting silane film becomes thicker, and its strength may decrease. Therefore, the concentration of alkyl silicates or their oligomers in the metal treatment solution is preferably less than 1% by mass, more preferably less than 0.5% by mass, and even more preferably less than 0.2% by mass.

[0080] On the other hand, if the concentration of alkyl silicates or their oligomers in the metal processing solution is less than 0.005% by mass, the concentration of alkyl silicates or their oligomers is too low, and therefore the composite oxide film of metal and silicon constituting the metal substrate cannot be sufficiently formed, which may result in insufficient adhesion durability. Therefore, the concentration of alkyl silicates or their oligomers in the metal processing solution is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.02% by mass or more.

[0081] Furthermore, the concentration of the organosilane compound in the metal treatment solution is preferably 0.005% by mass or more and less than 1% by mass. If the concentration of the organosilane compound in the metal treatment solution is 1% by mass or more, the resulting silane film becomes thicker, and its strength may decrease. In addition, the stability of the solution also decreases. Therefore, the concentration of the organosilane compound in the metal treatment solution is preferably less than 1% by mass, more preferably less than 0.5% by mass, and even more preferably less than 0.2% by mass.

[0082] On the other hand, if the concentration of the organosilane compound in the metal treatment solution is less than 0.005% by mass, the concentration of the organosilane compound is too low, and therefore a surface treatment film containing the organosilane compound cannot be sufficiently formed, resulting in insufficient adhesion durability. Therefore, the concentration of the organosilane compound in the metal treatment solution is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.02% by mass or more.

[0083] Let X be the mass of the alkyl silicate ester or its oligomer contained as a silane compound in the metal processing solution, and Y be the mass of the hydrolysate or polymer of the organosilicon compound. The ratio of X to Y is preferably 4:1 to 1:4. More preferably, the ratio of X to Y is 2:1 to 1:2. To control the polymerization of these substances and stabilize the metal processing solution, the metal processing solution preferably contains 1% by mass or less of an acid relative to the total mass of the silane compound.

[0084] In silane films composed of hydrolysates or polymers of alkyl silicates or their oligomers and organosilane compounds, it is preferable to adjust the film amount to an optimal range to achieve sufficient adhesive durability. If the film amount of the silane film is less than 0.1 mg / m³...2 If the coating cannot adequately cover the metal surface, the desired adhesion durability may be difficult to achieve. On the other hand, if the coating amount of the silane coating exceeds 20 mg / m³, [further issues may arise]. 2 If the silane film becomes too thick, its adhesion to the metal substrate will be insufficient, potentially leading to damage starting from the silane film and making it difficult to achieve the desired bond strength. Therefore, the preferred silane film weight is 0.1 mg / m³. 2 Above and 20mg / m 2 The following is more preferably 0.5 mg / m³ 2 Above and 15mg / m 2 The following describes how a metal processing solution is prepared by designing the ratio of X to Y in the above-mentioned range, thereby achieving an optimal film weight for the silane film.

[0085] The types of alkyl silicates or their oligomers contained in the metal processing solution are not particularly limited, but from the viewpoint that byproducts causing film corrosion and adhesive resin deterioration should not occur after the reaction, silicates and tetraalkoxy esters of orthosilicate or their oligomers are preferred. Among these, tetraethoxysilane (TEOS) or its polymers (oligomers) are preferred because they are neutral and do not leave alkali residue after the formation of the silane film. Furthermore, oligomers may be included in the polymer. Here, only one type of alkyl silicate or its oligomer can be used, or two or more can be used in combination.

[0086] The types of organosilane compounds contained in metal treatment solutions are not particularly limited, but they may include silane compounds with multiple hydrolyzable trialkoxy groups within their molecules, their hydrolysates, or polymers thereof. Silane compounds with multiple hydrolyzable trialkoxy groups within their molecules not only form dense siloxane bonds through self-polymerization but also exhibit high reactivity with metal oxides, forming chemically stable bonds, thus further improving the durability of the silane film. Furthermore, the silane film has high miscibility with organic compounds such as machining oils, stamping oils, and adhesives. Even if machining oils or stamping oils adhere to the film, their influence can be mitigated, thus also preventing a decrease in adhesion durability caused by oiling. The types of silane compounds mentioned above are not particularly limited, but from an economic point of view, silane compounds having two hydrolyzable trimekrosilicon groups (bissilane compounds) are preferred. For example, bis(trialkoxysilyl)ethane and bis(trialkoxysilyl)benzene can be used. Organosilanes include bis(triethoxysilyl)hexane, bis(trialkoxysilylpropyl)amine, and bis(trialkoxysilylpropyl)tetrasulfide. From the viewpoints of versatility, formulation properties, and stability in aqueous solutions, bis(trialkoxysilyl)ethane is preferred, and bis(triethoxysilyl)ethane (BTSE) is even more preferred. Here, as organosilanes, one type may be used alone, or two or more may be used in combination.

[0087] In addition, organosilane compounds may also include silane coupling agents, their hydrolysates, or polymers having reactive functional groups capable of chemically bonding with organic resin components. For example, by using silane coupling agents having reactive functional groups such as amino, epoxy, methacrylate, vinyl, and mercapto groups alone, or in combination with silane compounds, chemical bonds can be formed between the film and the resin, further improving adhesive durability. Furthermore, the functional groups of silane coupling agents are not limited to those mentioned above; silane coupling agents with various functional groups can be appropriately selected depending on the adhesive resin used. Preferred examples of silane coupling agents include, for instance, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(N-aminoethyl)-aminopropyltrimethoxysilane, 3-(N-aminoethyl)-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-glycidyletherylpropyltrimethoxysilane, 3-glycidyletherylpropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and so on. Here, as a silane coupling agent, one can be used alone, or two or more can be used in combination.

[0088] In this embodiment, if the metal processing solution contains particulate inorganic compounds with a diameter of 10 nm or more (hereinafter also simply referred to as "particulate inorganic compounds"), an additional step such as water washing is required to remove them after the formation of the silane film. Furthermore, the formed silane film becomes thicker, potentially reducing adhesion strength and durability. Therefore, it is preferable that the metal processing solution is substantially free of particulate inorganic compounds. Also, the phrase "the metal processing solution is substantially free of particulate inorganic compounds" does not mean it is completely free of particulate inorganic compounds, but rather that it allows the presence of particulate inorganic compounds at an impurity level. Specifically, the amount of particulate inorganic compounds allowed is up to 0.05% by mass or less relative to the total amount of the metal processing solution. Examples of particulate inorganic compounds include sols of inorganic oxides such as silica and alumina. Furthermore, the diameter of the particulate inorganic compounds refers to the diameter of the solid component after the processing solution has dried, as observed by a transmission electron microscope (TEM), or the diameter measured in a diluted processing solution using a particle counter.

[0089] Furthermore, in addition to the aforementioned alkyl silicates or their oligomers, and organosilane compounds, the metal processing solution may also contain one or more stabilizers, auxiliaries, etc., as needed. For example, as a stabilizer, it may contain organic compounds such as carboxylic acids with 1 to 4 carbon atoms, such as formic acid and acetic acid, or alcohols with 1 to 4 carbon atoms, such as methanol and ethanol.

[0090] Furthermore, as a method for preparing a solution for metal processing, the following preparation method can be cited as an example, but is not limited to: First, an organosilane compound and a small amount of acetic acid as a catalyst are added to a mixture of an alcohol such as ethanol and water, causing the organosilane compound to be fully hydrolyzed to obtain an aqueous solution of the organosilane compound. Second, an aqueous solution of an alkyl silicate or its oligomer is prepared by the same method. After mixing these two liquids, they are diluted with water to reach a specified concentration, thereby preparing a solution for metal processing. In addition, since alkyl silicates or their oligomers are basic and readily polymerize, when using a basic compound as the organosilane compound, it is preferable to neutralize the organosilane solution with acetic acid or the like before preparing the solution to avoid excessive polymerization of the alkyl silicate or its oligomers during solution mixing.

[0091] [Connector]

[0092] The joint in this embodiment contains the aforementioned surface-treated metal material. Specifically, the joint is formed by bonding a first component and a second component together via an adhesive resin layer. Furthermore, at least one of the first component and the second component may be the aforementioned surface-treated metal material, and the silane film of the surface-treated metal material is bonded to the adhesive resin layer.

[0093] The bond constructed in this embodiment, as described above, exhibits excellent bonding durability and its bonding strength is difficult to decrease even when exposed to high temperature and humid environments. As mentioned above, either the first component or the second component may be the surface-treated metal material of the present invention, or both components may be the surface-treated metal material of the present invention. When only one component (the first component) is a surface-treated metal material, the other component (the second component) can be an untreated metal material, an untreated resin molded body, etc. As an untreated metal material, various metal materials can be used besides titanium or titanium alloys, aluminum or aluminum alloys, copper or copper alloys, and stainless steel.

[0094] Furthermore, as resin molded bodies, fiber-reinforced plastic molded bodies formed from various fiber-reinforced plastics such as glass fiber reinforced plastic (GFRP), carbon fiber reinforced plastic (CFRP), boron fiber reinforced plastic (BFRP), aramid fiber reinforced plastic (AFRP, KFRP), polyethylene fiber reinforced plastic (DFRP), and Zylon reinforced plastic (ZFRP) can be used. By using these fiber-reinforced plastic molded bodies, a certain strength can be maintained while making the bonded body lightweight.

[0095] In addition to the fiber-reinforced plastics mentioned above, unreinforced engineering plastics such as polypropylene (PP), acrylonitrile-butadiene-styrene copolymer (ABS) resin, polyurethane (PU), polyethylene (PE), polyvinyl chloride (PVC), nylon 6, nylon 6,6, polystyrene (PS), polyethylene terephthalate (PET), polyamide (PA), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), and polyphthalamide (PPA) can also be used as resin molded bodies.

[0096] When the first component and the second component are surface-treated metal materials of the present invention, the types of metal substrates can be the same or different, and various combinations of metal substrates can be used.

[0097] [Method for manufacturing the joint]

[0098] The joint of this embodiment can be manufactured by conventionally known methods. For example, an adhesive resin layer can be formed in the area where the silane film is formed by a known method, and other components can be joined in contact with the adhesive resin layer. The method of forming the adhesive resin layer is not particularly limited, but as described above, an adhesive sheet made of adhesive resin material can be used, or a method of spraying or coating the adhesive resin material onto the surface of the silane film can be used.

[0099] The above embodiments illustrate an example of a surface-treated metal material with an adhesive resin layer formed for manufacturing a bond. However, this invention is not limited to the above examples; other surface-treated metals may have a coating formed on at least a portion of the silane film. In surface-treated metal materials with a coating, the adhesion between the stainless steel substrate and the silane film is excellent, and the adhesion between the silane film and the coating is also excellent, thus preventing coating peeling.

[0100] Example

[0101] The present invention will now be described in more detail by way of inventive examples and comparative examples. However, the present invention is not limited to these embodiments, and modifications can be made within the scope of the spirit of the present invention, all of which are included within the technical scope of the present invention. In addition, the following manufacturing conditions are examples, and the embodiments are not limited to the following conditions.

[0102] [Preparation of test materials]

[0103] <Preparation of Substrate>

[0104] First, cut plates made of various metal materials to a length of 100 mm and a width of 25 mm, preparing two metal substrates for each test condition. The types of metal materials are shown below.

[0105] Aluminum alloy (JIS standard A7075): Plate thickness 3.8mm

[0106] Aluminum alloy (JIS standard A5052): Plate thickness 2mm

[0107] Pure titanium (JIS standard type 1): Plate thickness 1.2mm

[0108] Stainless steel (JIS standard SUS304): 1mm thick

[0109] <Shot Peening>

[0110] Secondly, the evaluation range for the metal substrate was set to 10 mm from the longitudinal end and 25 mm from the width. For the substrates of Invention Examples No. 1-5 and Comparative Examples No. 4, 9, and 10, shot peening was performed within the above evaluation range using either a dry or wet method, followed by washing with water for 1 minute. The shot peening conditions are as follows. Furthermore, for Comparative Examples No. 1-3 and 5-8, which did not undergo shot peening, only acetone cleaning was performed.

[0111] (Dry shot peening conditions)

[0112] Dry shot peening equipment: Nippon Seiki Co., Ltd. shot peening equipment (NAB-3K)

[0113] Abrasive: White corundum manufactured by Showa Denko Co., Ltd.; Abrasive grain: WA#150

[0114] Shot peening pressure: 0.7 (MPa)

[0115] (Wet shot peening conditions)

[0116] Wet shot peening equipment: BABY BlastII (Model: MBBII-25) manufactured by Moko Co., Ltd.

[0117] Abrasive: White corundum manufactured by Showa Denko Co., Ltd.; abrasive grains: WA#150, WA#320

[0118] Air pressure: 0.12 MPa

[0119] Spray gun movement speed 10mm / sec

[0120] <Formation of Silane Film>

[0121] Subsequently, the substrates of Invention Examples No. 1 to 5 and Comparative Examples No. 5 to 8 were immersed in a metal processing solution containing silicon compound 1 and silicon compound 2 as shown below at room temperature for 10 seconds, and then lifted out. Then, they were dried in a forced-air drying oven at a temperature of 100°C for 60 seconds, thereby producing a silane film and obtaining the test material.

[0122] (Metal processing solution)

[0123] Silicon compound 1: bis(triethoxysilyl)ethane (BTSE) 0.1g

[0124] Silicon compound 2: Tetraethoxysilane (TEOS) 0.1g

[0125] 2.0g of ethanol

[0126] Acetic acid 0.001g

[0127] 97.8g of water

[0128] [Measurement of the surface of the test material]

[0129] <Measurement of Str (Aspect Ratio)>

[0130] For the surface of each test material (the surface of the silane film), the surface roughness was measured using a laser microscope (KEYENCE VK-X150 / 160 morphology analysis laser microscope) over a 1 mm × 1 mm measurement area at any three locations (location 1, location 2, and location 3). Furthermore, as a measurement condition, the aspect ratio was measured with the objective lens magnification set to 20x, and the average value at the three locations was calculated.

[0131] <Absorption Spectra Measurement by FT-IR>

[0132] For the surface of each test material (the surface of the silane film), the absorption spectrum was measured using FT-IR (Fourier Transform Infrared Spectrophotometer: Nicolet Magna-750 spectrometer). Specifically, parallel polarized light with an incident angle of 75° was incident, the absorption spectrum was measured, and the measurement was taken at 1250 cm⁻¹. －1 ) and above and 1150 (cm) －1 The following wavenumber regions are checked for absorption peaks. For those with peaks, absorbance is measured. The manufacturing conditions, aspect ratio, and absorbance measurement results of the test material are shown in Table 1 below.

[0133] [Preparation of the bonding test specimen]

[0134] Subsequently, the two test materials are bonded together with an adhesive to obtain the bonded test body (bonded body). Figure 2A This is a side view showing the shape of the joint test specimen. Figure 2B This is its top view. For example... Figure 2A and Figure 2BAs shown, an adhesive resin layer 35 is formed on the surface of the test material 31b (second component) within the aforementioned evaluation area. A test material 31a (first component) having the same structure as the test material 31b is then overlapped on this adhesive resin layer 35. Furthermore, the overlap length is 10 mm, with the test material 31a and test material 31b overlapping only in the area 10 mm from their ends.

[0135] Regarding Invention Examples No. 1-5 and Comparative Examples No. 5-8, since a silane film was formed within the aforementioned evaluation range, the adhesive resin layer 35 was configured such that 10mm × 25mm regions with the silane film formed were placed opposite each other. Furthermore, a thermosetting epoxy resin adhesive for construction was used as the material for the adhesive resin layer. Additionally, a small amount of glass beads (250μm particle size) was added to the adhesive resin material to adjust the thickness of the adhesive resin layer 35 to 250μm. After being stacked as described above, the layers were dried at room temperature for 30 minutes, and then heated at 180°C for 30 minutes to perform a thermosetting treatment. Afterward, the layers were left to stand at room temperature for 24 hours to produce a bonding test specimen (bonded body).

[0136] For Comparative Examples No. 1-3 and 5-8, the bonding test specimens were prepared in the same manner as described above, with the acetone-cleaned surfaces facing each other via the adhesive resin layer 35. For Comparative Examples No. 4, 9 and 10, the bonding test specimens were prepared in the same manner as described above, with the shot-peened surfaces facing each other via the adhesive resin layer 35.

[0137] [Evaluation of the conjugation test specimens]

[0138] <Deterioration Test>

[0139] A degradation test was performed on a portion of the resulting joints to evaluate bond durability. The degradation test was conducted by immersing the joints in a 5% NaCl solution at 40°C for the period shown in Table 1 below.

[0140] <Tension Test>

[0141] Tensile tests were performed on the resulting bonded specimens to evaluate adhesion. As a tensile condition, the two ends of the bonded specimens were stretched along... Figure 2AThe material was stretched in the direction indicated by the middle arrow at a stretching speed of 50 mm / min until it fractured. Then, the fracture surfaces of the surface-treated metal material 31a (first component) and surface-treated metal material 31b (second component) were observed, and the area of ​​the region where interfacial peeling occurred between the surface-treated metal material 31a and the adhesive resin layer (interfacial peeling area of ​​the first component) and the area of ​​the contact surface between the surface-treated metal material 31a and the adhesive resin layer (adhesive area of ​​the first component) were measured. Similarly, the area of ​​the region where interfacial peeling occurred between the surface-treated metal material 31b and the adhesive resin layer (interfacial peeling area of ​​the second component) and the area of ​​the contact surface between the surface-treated metal material 31b and the adhesive resin layer (adhesive area of ​​the second component) were also measured. Then, the cohesive failure rate was calculated according to the following formula (2). The conditions of the degradation test and the calculation results of the cohesive failure rate are shown together in Table 1 below.

[0142] Cohesion failure rate (%) = 100 - {(interfacial peel area of ​​the first component / adhesive area of ​​the first component) × 100 + (interfacial peel area of ​​the second component / adhesive area of ​​the second component) × 100} ... (2)

[0143] Table 1

[0144]

[0145] As shown in Table 1 above, Invention Examples No. 1 to 5 are examples of test subjects using a silane film on the surface. The average aspect ratio is within the range specified in this invention, and absorption peaks are present within the specified range. Therefore, regardless of the type of substrate, excellent cohesive failure rate is exhibited. Furthermore, even after immersion in NaCl solution, excellent cohesive failure rate is still observed, indicating excellent adhesive durability.

[0146] On the other hand, Comparative Example No. 1 did not form a silane film, the average aspect ratio deviated from the range specified in this invention, and there were no absorption peaks within the specified range. Therefore, the cohesive failure rate after the degradation test was low.

[0147] Comparative Example No. 2 did not form a silane film, and the average aspect ratio deviated from the range specified in this invention. Therefore, the cohesive failure rate after the degradation test was low.

[0148] Comparative Example No. 3 did not form a silane film and had no absorption peaks within the specified range. Therefore, even without impregnation during a degradation test, the cohesive failure rate was low.

[0149] Comparative Example No. 4 did not form a silane film and had no absorption peaks within the specified range, therefore its cohesive failure rate after the degradation test was low.

[0150] Although Comparative Examples No. 5, 6 and 8 formed silane films and had absorption peaks within the specified range, their average aspect ratios deviated from the range specified in this invention, resulting in low cohesive failure rates after the degradation test.

[0151] Although Comparative Example No. 7 has a silane film and has absorption peaks within the specified range, the average aspect ratio deviates from the range specified in this invention. Therefore, even without impregnation during a degradation test, the cohesive failure rate is low.

[0152] Comparative Examples No. 9 and 10, although the average aspect ratio is within the range specified in this invention, did not form a silane film and no absorption peak was found within the specified range. Therefore, the cohesive failure rate after the degradation test was low.

[0153] The above descriptions of various embodiments are not limited to these examples. Those skilled in the art will readily conceive of various modifications and alterations within the scope of the patent claims, and these are also considered to fall within the technical scope of this invention. Furthermore, the constituent elements of the above embodiments can be combined arbitrarily without departing from the spirit of the invention.

[0154] Furthermore, this application is based on Japanese patent applications filed on May 15, 2023 (Takumi 2023-080411) and February 14, 2024 (Takumi 2024-020418), the contents of which are incorporated herein by reference.

[0155] Explanation of reference numerals in the attached figures

[0156] 31a Surface-treated metallic material (first component)

[0157] 31b Surface-treated metallic material (second component)

[0158] 35 Adhesive resin layer

Claims

1. A surface-treated metallic material, characterized in that, It is a surface-treated metallic material having a silane film on at least a portion of the surface of a metallic substrate, wherein, When parallel polarized light with an incident angle of 75° is incident on the surface of the silane film, and the absorption spectrum is measured by Fourier transform infrared spectroscopy, the absorption spectrum at 1250 cm⁻¹ is observed. －1 Above and 1150cm －1 The following wavenumber regions have absorption peaks, and the absorbance of said absorption peaks is 0.003 or higher. On the surface of the silane film, for any three locations within a 1mm × 1mm measurement range, when the surface roughness is measured using a laser microscope, the aspect ratio Str of the surface properties is greater than or equal to 0.

8.

2. The surface-treated metal material according to claim 1, characterized in that, An adhesive resin layer is present on the surface of the silane film.

3. The surface-treated metal material according to claim 1, characterized in that, The metal substrate is one of pure titanium, titanium alloy, and stainless steel.

4. A joint, characterized in that, It is a joint containing the surface-treated metallic material according to any one of claims 1 to 3, wherein, The first component and the second component are joined together via an adhesive resin layer. Either the first component or the second component is the surface-treated metal material. The silane film of the surface-treated metal material is bonded to the adhesive resin layer.

5. A joint, characterized in that, It is a joint containing the surface-treated metallic material according to any one of claims 1 to 3, wherein, The first component and the second component are joined together via an adhesive resin layer. Both the first component and the second component are surface-treated metal materials having a metal substrate formed of the same or different metal materials. The silane film of the first component and the silane film of the second component are bonded together by the adhesive resin layer.

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