Method for manufacturing surface-treated metal material and method for manufacturing joined body

Abstract

To provide a method for manufacturing a surface-treated metal, capable of reducing a load to the environment without requiring a complicated pretreatment step and a pretreatment solution before a step of depositing a film on a surface and capable of easily depositing a surface-treated film at low cost.SOLUTION: A method for manufacturing a surface-treated metal having a silane film provided on at least a part of the surface of a metal base material 1 comprises: a blast processing step of projecting abrasive grains 2 for blast processing on the area R of the at least a part of the surface of the metal base material; a deposition step of depositing a silane compound containing solution for metal processing on the surface of the metal base material 1 subjected to blast processing; and a drying step of drying the metal base material 1 deposited with the solution for metal processing to deposit the silane film.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a method for producing a surface-treated metal material and a method for producing a joined body including the surface-treated metal material. [Background technology]

[0002] In the field of transportation such as automobiles, ships and aircraft, adhesive joining is used as a joining technique between dissimilar materials such as steel and lightweight materials (aluminum alloys, titanium alloys, carbon fiber, etc.) from the viewpoint of weight reduction.In addition, adhesive joining is attracting attention as an alternative to welding from the viewpoint of improving productivity and workability in response to on-site issues such as a lack of successors for welders, skill transfer, and improving the work environment.

[0003] On the other hand, adhesive bonding has issues with strength reliability during long-term use. It is known that adhesive bonding is more susceptible to strength degradation than welding or bolting in high-temperature, high-humidity environments, and environments where stresses such as fatigue and creep act in combination. In adhesive bonding, adhesion between the adhesive and the metal substrate is important. Insufficient adhesion between the metal material surface and the adhesive allows water to penetrate the interface between the metal and the resin. This results in corrosion of the metal surface and delamination at the interface, significantly reducing adhesive strength. Therefore, improving the adhesion between the metal and the adhesive resin prevents water penetration at the adhesive interface. Furthermore, to prevent water from easily changing the metal surface even if water does penetrate, it is necessary to modify the surface of the metal material to create a surface condition suitable for adhesion.

[0004] To solve the above problems, various surface treatment techniques have been proposed. For example, Patent Document 1 proposes a method for producing an aluminum surface-treated material, which includes a coating step of applying a treatment solution containing a silane compound in a predetermined amount to the surface of a substrate made of an Al-Mg alloy or an Al-Mg-Si alloy. Furthermore, the method for producing the aluminum surface-treated material includes, after the coating step, a drying step for forming the treatment solution into a film, and a water-washing step for forming a film having a predetermined film amount and element concentration ratio, thereby forming a film with excellent adhesion durability.

[0005] Patent Document 2 proposes a method for producing an aluminum alloy material, which includes an oxide film forming step of forming a predetermined oxide film on at least a portion of the surface of an aluminum alloy substrate, and a surface treatment film forming step of applying a specific aqueous solution to at least a portion of the oxide film. The aqueous solution contains a silicate of the oxide film and an organosilane compound, and has an adjusted pH. This makes it possible to produce an aluminum alloy material that is less likely to lose adhesive strength, has excellent adhesive durability, and is highly productive.

[0006] Furthermore, Patent Document 3 discloses an aluminum coating material in which a silica-containing coating containing water-dispersible silica, phosphoric acid, and a silane coupling agent is formed on the surface of an aluminum material as an adhesive primer coating. The silica-containing coating has a specified mass ratio of P content to Si content, which allows it to achieve excellent adhesion strength and corrosion resistance.

[0007] Furthermore, Patent Document 4 discloses a preparation method including a step of roll-coating an aqueous functionalizing solution onto a prepared aluminum alloy product and a step of drying the solution. The aqueous functionalizing solution contains a first monomer component and a second polymer component, and the relationship between the amounts of each component is adjusted. This can improve bonding durability.

[0008] Furthermore, Patent Document 5 describes a method for producing a surface-treated aluminum alloy sheet, in which a substrate made of an aluminum alloy containing Mg is subjected to an acid etching treatment so that the etching amount E satisfies a predetermined relationship, and then the substrate is subjected to a chemical conversion treatment to form an inorganic coating containing Mg, Ti, and Zr. The production method described in Patent Document 5 makes it possible to obtain a surface-treated aluminum alloy sheet with excellent adhesion durability. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2017-197838 [Patent Document 2] Japanese Patent Application Publication No. 2017-203209 [Patent Document 3] International Publication No. 2018 / 207685 [Patent Document 4] Japanese Patent Application Publication No. 2020-528339 [Patent Document 5] Patent No. 7084957 Summary of the Invention [Problem to be solved by the invention]

[0010] However, the techniques described in Patent Documents 1 to 5 require a pretreatment step for surface treatment, which involves a degreasing treatment using an alkaline aqueous solution to remove oil and other contaminants adhering to the material surface, and an acid pickling treatment using sulfuric acid, hydrofluoric acid, or nitric acid to remove an oxide film. Furthermore, Patent Documents 3 to 5 also use an acidic treatment solution containing hydrofluoric acid or phosphoric acid in the surface treatment step. This requires that the treatment equipment be designed using highly corrosion-resistant metals such as stainless steel. Even if the treatment equipment is made of such highly corrosion-resistant metals, it will deteriorate due to the exposure to these chemicals over long periods of use.

[0011] Furthermore, the surface treatment and pretreatment processes generate large amounts of waste liquids containing alkalis, acids, hydrofluoric acid, and phosphoric acid, necessitating the disposal of these industrial wastes. Furthermore, the alkalis, acids, and various chemicals contained in the surface treatment solutions are consumed during the surface treatment of materials, and the solutions deteriorate as the metals in the base material are eluted. Therefore, strict management of treatment conditions is required, such as constant monitoring of the solution state and adjusting the treatment temperature and treatment time or replenishing chemicals depending on the solution state. Such processes are undesirable from environmental, economic, and production standpoints. To achieve the goal of a sustainable society, which is a modern challenge for humanity, it is necessary to improve processes that generate large amounts of such hazardous waste liquids and are disadvantageous in productivity and economic efficiency.

[0012] The present invention has been made in consideration of these problems, and aims to provide a method for producing a surface-treated metal material that does not require a complex pretreatment step or pretreatment solution prior to the step of forming a coating on the surface, thereby reducing the burden on the environment and enabling a surface treatment coating to be formed easily and at low cost, as well as a method for producing a joined body that includes this surface-treated metal material. [Means for solving the problem]

[0013] The above object of the present invention is achieved by the following configuration [1] relating to a method for producing a surface-treated metal material.

[0014] [1] A method for producing a surface-treated metal material having a silane coating on at least a portion of the surface of a metal substrate, comprising: a blasting step of subjecting at least a portion of the surface of the metal substrate to blasting; a coating step of coating the surface of the metal substrate that has been subjected to the blast treatment with a metal treatment solution containing a silane compound; and a drying step of drying the metal substrate coated with the metal treatment solution to form a silane coating.

[0015] Furthermore, preferred embodiments of the present invention relating to the method for producing a surface-treated metal material relate to the following [2] to

[10] .

[0016] [2] The method for producing a surface-treated metal material according to [1], characterized in that a cleaning step is not carried out after the drying step.

[0017] [3] The metal treatment solution contains a silane compound in an amount of 0.01% by mass or more and 1% by mass or less, The method for producing a surface-treated metal material according to [1] or [2], characterized in that the silane compound contains an alkyl silicate or an oligomer thereof, and a hydrolyzate of an organic silane compound or a polymer thereof.

[0018] [4] Between the blasting process and the deposition process, a water washing step of washing the metal base material that has been subjected to the blast treatment with water, The method for producing a surface-treated metal material according to any one of [1] to [3], characterized in that the deposition process is carried out while water from the water washing process is still attached to the surface that has been subjected to the blasting process.

[0019] [5] A method for producing a surface-treated metal material according to any one of [1] to [4], characterized in that the time from the end of the blasting process to the start of the deposition process is within 8 hours.

[0020] [6] A method for producing a surface-treated metal material according to any one of [1] to [5], wherein the content of particulate inorganic compounds having a diameter of 1 nm or more is 0.05 mass % or less relative to the total mass of the metal treatment solution.

[0021] [7] The deposition step a coating step of applying the metal treatment solution to the metal substrate, thereby depositing the metal treatment solution on the surface of the metal substrate; a recovery step of recovering excess metal treatment solution generated by the application step, The method for producing a surface-treated metal material according to any one of [1] to [6], characterized in that the excess metal treatment solution is reused in the deposition step when producing another surface-treated metal material.

[0022] [8] The deposition step The method for producing a surface-treated metal material according to any one of [1] to [6], characterized by comprising an immersion step of immersing the metal substrate in the metal treatment solution to thereby coat the metal treatment solution on the surface of the metal substrate.

[0023] [9] The method for producing a surface-treated metal material according to any one of [1] to [8], wherein the silane coating has an adhesive or paint applied directly to its surface.

[0024]

[10] The surface-treated metal material has a functional layer in contact with the surface of the silane coating, the functional layer is an adhesive resin layer or a coating film formed by the adhesive or paint, After the drying step, [9] The method for producing a surface-treated metal material according to [9], characterized by comprising a functional layer formation step of forming the functional layer on the surface of the silane coating.

[0025] The above object of the present invention is achieved by the following configuration

[11] relating to a method for producing a bonded body.

[0026]

[11] A method for producing a joined body including a surface-treated metal material produced by the production method according to any one of [1] to [8], a joining step of joining the first member and the second member via an adhesive resin layer, At least one of the first member and the second member is the surface-treated metal material, A method for manufacturing a joined body, characterized in that in the joining step, the silane coating of the surface-treated metal material and the adhesive resin layer are arranged to be in contact with each other, thereby joining the first member and the second member. [Effects of the Invention]

[0027] According to the present invention, a method for producing a surface-treated metal material that does not require a complex pretreatment step or pretreatment solution prior to the step of forming a coating on the surface, thereby reducing the burden on the environment and enabling a surface treatment coating to be formed easily and at low cost, and a method for producing a joined body that includes this surface-treated metal material can be provided. [Brief explanation of the drawings]

[0028] [Figure 1A] FIG. 1A is a diagram showing the order of steps in a method for producing a surface-treated metal material according to an embodiment of the present invention, and is a perspective view showing a blasting treatment step. [Figure 1B]FIG. 1B is a diagram showing the process steps of a method for producing a surface-treated metal material according to an embodiment of the present invention, and is a perspective view showing a deposition step. [Figure 1C] FIG. 1C is a diagram showing the process steps of a method for producing a surface-treated metal material according to an embodiment of the present invention, and is a perspective view showing a drying step. [Figure 2A] FIG. 2A is a side view showing the shape of the bonded body. [Figure 2B] FIG. 2B is a plan view showing the shape of the bonded body. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present inventors have conducted extensive research into a method for manufacturing a surface-treated metal material that can be applied to adhesive bonding even for difficult-to-bond metal materials such as stainless steel and titanium, that saves resources and energy, and that can be easily manufactured at low cost. As a result, they have found that the above-mentioned problems can be solved by using a silane coating that has excellent adhesion to adhesive resins and by simplifying the pretreatment step of forming this silane coating. A method for manufacturing a surface-treated metal material according to an embodiment of the present invention will now be described.

[0030] [Method of manufacturing surface-treated metal materials] The surface-treated metal material produced by the production method according to an embodiment of the present invention has a silane coating provided on at least a portion of the surface of a metal substrate. Each step will be described below with reference to the drawings. Figures 1A to 1C are perspective views showing the process steps of the production method for a surface-treated metal material according to an embodiment of the present invention.

[0031] <Blast treatment process> As shown in FIG. 1A, first, a blasting treatment is performed on at least a portion of the surface of the metal substrate 1, region R. Specifically, abrasive grains 2 for blasting or a solution containing abrasive grains are projected onto region R at high speed using compressed air, a motor, or the like. This allows contaminants, deposits, and oxide films present on the surface of the metal substrate 1 to be removed and cleaned without using chemicals or the like. Furthermore, the blasting treatment forms an uneven shape in region R, which improves adhesion to the silane film formed in the next process.

[0032] (Type of blasting) The type of blasting used in the blasting process is not particularly limited; either a dry blasting method or a wet blasting method can be used, with similar results being achieved. For example, a dry blasting method is economically preferable because the equipment is small and versatile; however, heat generated during blasting can affect the condition of the oxide film on the surface of the metal substrate 1. Furthermore, abrasive particles remaining on the surface of the material after blasting can affect the formation and adhesive strength of the silane film. On the other hand, a wet blasting method reduces heat input to the surface of the metal substrate 1 and suppresses abrasive particle residue, making it preferable from the perspectives of dust control and process stability; however, it requires larger equipment, which can increase costs. Therefore, the method to be used can be selected based on the desired effect.

[0033] In this embodiment, the type of abrasive grain is not particularly limited, and commercially available abrasive grains can be used. The particle size of the abrasive grains and the pressure when projecting the abrasive grains are also not particularly limited, and can be under commonly used conditions, for example, the particle size can be 1 to 1000 μm and the pressure can be 0.01 to 1.0 MPa.

[0034] <Water washing process> After the blasting step, a water-washing step may be performed in which the metal substrate 1 that has been subjected to the blasting step is washed with water. This water-washing step is also expected to have a protective effect of preventing excess contaminants from being adsorbed onto the metal substrate 1 from the atmosphere until the metal processing solution is applied in the subsequent coating step. Therefore, it is preferable to perform the water-washing step if possible. Furthermore, if the water-washing step is performed, it is more preferable to keep the metal substrate 1 in a state where the water from the water-washing step is attached until the subsequent coating step is performed, in order to prevent surface contamination.

[0035] <Adhesion process> Next, as shown in FIG. 1B , a metal treatment solution 3 containing a silane compound is applied to a region R on the surface of the metal substrate 1 that has been subjected to the blasting treatment. In the application step, the application should be performed so that an appropriate amount of the main component, mainly the silane compound, is present on the surface of the metal substrate 1. Therefore, the method for applying the metal treatment solution 3 to the surface of the metal substrate 1 is not particularly limited, and may be a coating method or a dipping method. Examples of application methods include spraying, showering, roll coating, and brush application, and it is preferable to select an appropriate application method depending on the shape of the metal substrate 1 and the area to be treated.

[0036] (Timing for carrying out the deposition process) The timing for starting the deposition process is not particularly limited as long as it is after the blast treatment process is completed. However, if the surface of the metal substrate 1 that has been subjected to the blast treatment is contaminated before the deposition process is started, the formation of chemical bonds between the silane compound in the metal treatment solution and the oxide film on the surface of the metal substrate 1 will be inhibited. Therefore, it is preferable that the time from the end of the blast treatment process to the start of the deposition process be as short as possible, specifically, within 8 hours, and more preferably within 6 hours.

[0037] (Application process / recovery process) The deposition process preferably includes an application process in which the metal treatment solution 3 is applied to the metal substrate 1 to deposit the metal treatment solution 3 on the surface of the metal substrate 1, and a recovery process in which excess metal treatment solution generated by the application process is recovered. Unlike conventional immersion processes using organic phosphonic acid or hydrofluoric acid, this embodiment allows the metal treatment solution 3 to be used without reducing the silane compound concentration, and prevents deterioration of the solution due to elution of components from the metal substrate 1. Furthermore, as will be described later, this embodiment allows a silane coating with excellent performance to be formed even when the silane compound concentration in the metal treatment solution is extremely low. Therefore, there is no need to replace the metal treatment solution 3 or strictly control its concentration, and the excess metal treatment solution recovered in the recovery process can be easily reused in the deposition process during the production of other surface-treated metal materials.

[0038] Therefore, when the above-mentioned application process is used as a method for applying the metal processing solution 3 to the metal substrate 1, it is preferable to provide a mechanism for recovering excess metal processing solution. It is also preferable to design the process so that the minimum necessary amount of metal processing solution 3 is applied. In this way, the consumption of the metal processing solution can be extremely reduced, and theoretically, it is possible to design a process that does not generate waste liquid.

[0039] (Soaking process) The above-mentioned coating step may be an immersion step in which the metal substrate 1 is immersed in the metal treatment solution 3 to coat the metal treatment solution 3 on the surface of the metal substrate 1. When the immersion step is used, the metal treatment solution 3 can be coated over a wide area of ​​the metal substrate.

[0040] <Drying process> 1C, the solvent is evaporated from the metal treatment solution applied to the surface of the metal substrate 1, and the metal substrate 1 is dried to promote the reaction between the silane compound and the oxide film and the polymerization of the silane compounds themselves. As a result, a silane film 4 is formed on at least a portion (region R) of the surface of the metal substrate 1, and a surface-treated metal material 10 can be produced.

[0041] When drying the metal substrate 1, the formation of the silane coating 4 is completed once the solvent has evaporated. Therefore, the drying temperature is not particularly limited and can be room temperature. However, because silane compounds form covalent bonds through dehydration condensation during oxidation and self-polymerization, a higher drying temperature can improve the adhesive properties of the silane coating. On the other hand, a higher drying temperature increases energy consumption, which is disadvantageous in terms of equipment and process costs. Therefore, it is preferable to select the drying temperature appropriately depending on the required adhesive properties and the level of productivity of the treatment. For example, a temperature of approximately 50 to 100°C is preferable, as it provides a good balance between productivity and energy consumption.

[0042] As a drying method, blowing air onto the metal substrate 1 is preferred from the viewpoints of drying speed and coating uniformity. Furthermore, if the metal substrate 1 is heated to a certain temperature during the manufacturing process of the surface-treated metal material 10, the metal substrate 1 can be cooled and the solvent removed at the same time, which is efficient and economical. To improve the integrity of the silane coating 4 and maximize the adhesive strength between the metal substrate 1 and the silane coating 4, it is preferable to repeat the deposition step and the drying step two to three times. Furthermore, repeating the deposition step and the drying step can also improve corrosion resistance.

[0043] <Cleaning process> In this embodiment, it is preferable not to perform a cleaning step after the drying step. In this embodiment, as described below, a metal treatment solution containing a silane compound at an extremely low concentration can be used. Therefore, a silane coating with excellent performance can be formed without performing a cleaning step. Furthermore, if the cleaning step can be omitted, the process can be simplified and no waste liquid is generated after cleaning, thereby reducing the burden on the environment.

[0044] <Functional layer formation process> Although not shown, it is preferable that a functional layer be further formed on the surface of the surface-treated metal material 10 manufactured by the manufacturing method according to this embodiment. Examples of functional layers include an adhesive resin layer formed with an adhesive or a coating film formed with a paint. Taking the adhesive resin layer as an example, an adhesive resin layer (not shown) is formed on the surface of the silane coating 4 after the drying process. As described above, by forming an adhesive resin layer on the surface of the silane coating, which has excellent adhesive bonding properties and durability, the process of adhesively bonding the surface-treated metal material 10 to similar surface-treated metal materials or other components can be simplified. Furthermore, forming a functional layer directly on the surface of the silane coating 4 can achieve excellent adhesive durability between the silane coating 4 and the functional layer.

[0045] The method for forming the adhesive resin layer is not particularly limited, but for example, an adhesive sheet made in advance from an adhesive resin material may be attached to the surface of the metal substrate 1, or the adhesive resin material may be sprayed or applied to the surface of the silane coating 4.

[0046] In the method for producing a surface-treated metal material according to the present embodiment, a silane coating is formed using a metal treatment solution containing silicon oxide. Silicon oxide is activated by dissolving it in an aqueous solution and can self-polymerize through a sol-gel reaction. A natural oxide coating is also formed on the metal substrate. Therefore, by applying the metal treatment solution to the oxide coating on the surface of the metal substrate, the oxide coating on the metal substrate reacts with the silicon oxide, and the silicon oxides also polymerize with each other. Therefore, a silane coating with excellent bonding strength to the metal substrate can be formed in a desired region on the surface of any metal substrate, regardless of the type or shape of the metal substrate.

[0047] Furthermore, the silane coating has high mutual solubility with machine oils such as processing oil and press oil, and organic compounds such as adhesives, and therefore has excellent bonding strength with adhesives. Furthermore, the silane coating can mitigate the effects of machine oils such as processing oil and press oil, even if they are attached, thereby preventing a decrease in adhesion durability due to oil application and achieving excellent corrosion resistance. Therefore, when the surface-treated metal material obtained by the manufacturing method according to this embodiment is adhesively bonded to another member, excellent bonding strength can be maintained for a long period of time.

[0048] Furthermore, conventional surface treatment methods require, for example, a degreasing step using an alkaline solution and a step of etching an oxide film using an acidic solution on the surface of a metal substrate, and also require the preparation of an alkaline solution for degreasing and an acidic solution for acid etching. Furthermore, treatments using these chemical solutions require an immersion bath for pretreating the metal substrate, and when the metal substrate is large, the equipment also becomes large, requiring a large amount of chemical solution. Furthermore, it is necessary to design an optimal chemical solution for acid etching depending on the type of metal substrate, and metal elution from the metal substrate causes deterioration of the chemical solution, limiting the number of times it can be reused, and waste liquid treatment is also costly.

[0049] In contrast, the manufacturing method according to the present embodiment eliminates the need for the conventional pretreatment process, and the blasting process can be performed without any further processing, allowing the subsequent deposition process to proceed. Furthermore, this blasting process allows abrasive grains to be projected only onto the desired region R of the surface of the metal substrate. Therefore, large-scale equipment is not required, capital investment can be reduced, and the pretreatment process can be simplified. Furthermore, the number of pretreatment steps can be significantly reduced, allowing the surface treatment film to be formed easily and at low cost. Furthermore, since no waste liquid is generated, the burden on the environment can be reduced. Furthermore, the blasting process forms fine irregularities on the surface of the metal substrate 1, thereby achieving excellent bonding between the silane film 4 formed on the surface of the surface-treated metal material and the metal substrate 1.

[0050] Furthermore, as described above, if the deposition process includes a recovery step of recovering excess metal treatment solution, the consumption of the metal treatment solution can be reduced and the generation of waste liquid can be suppressed. Furthermore, if such a recovery step is included, the concentration of the silane compound in the recovered excess metal treatment solution is checked before reuse, and no other management is required. Therefore, the running costs for producing surface-treated metal materials can be reduced and productivity can be increased.

[0051] Hereinafter, the materials such as the metal substrate, the metal treatment solution, and the adhesive resin used in the manufacturing method according to this embodiment will be described with specific examples.

[0052] (metal base material) The metal substrate may be any metal member, regardless of its type or shape. Examples of suitable metals include steel sheets, various plated steel sheets, pure aluminum or aluminum alloys, pure titanium or titanium alloys, stainless steel, copper or copper alloys, and the like. In particular, known aluminum alloys, such as Al-Mg alloys, Al-Mg-Si alloys, Al-Zn-Mg alloys, Al-Si alloys, and Al-Cu alloys, can be used. Known titanium alloys, such as α-titanium alloys, β-titanium alloys, and α+β-titanium alloys, can be used. Known stainless steels, such as austenitic stainless steels, ferritic stainless steels, martensitic stainless steels, and duplex stainless steels, can be used.

[0053] (Metal treatment solution) The metal treatment solution may be any solution containing a silane compound, and for example, a solvent containing 50% to 99.99% by mass of water and 0% to 50% by mass of an organic solvent may be used. The mass of water relative to the total mass of the solution is more preferably 50% to 99.95% by mass. From the viewpoints of reducing volatile organic compounds (VOCs) and reducing the risk of explosion, it is preferable that the solvent be primarily water. However, in order to reduce the surface tension of the metal treatment solution, improve water wettability and coatability, and increase the drying speed, the following organic solvents may be included:

[0054] When an organic solvent is used, various water-soluble solvents such as various alcohols and polyethers, for example, methanol, ethanol, propyl alcohol, butanol (including isomers), glycol solvents, and their ethers can be used.

[0055] The metal treatment solution preferably contains a silane compound in a content of 0.01% by mass or more and 1% by mass or less, and the silane compound preferably includes an alkyl silicate or its oligomer and a hydrolyzate or polymer of an organosilane compound. The concentration of the silane compound relative to the total mass of the metal treatment solution is more preferably 0.05% by mass or more and 0.5% by mass or less. The concentration of the silane compound can be adjusted based on factors such as the amount of the metal treatment solution to be applied to the surface of the metal substrate. Specifically, the silane compound contained in the metal treatment solution preferably includes an alkyl silicate or its oligomer in a content of 0.005% by mass or more and less than 1% by mass, and a hydrolyzate or polymer of an organosilane compound in a content of 0.005% by mass or more and less than 1% by mass.

[0056] When the specific metal treatment solution described above is applied to at least a portion of the surface of a metal substrate, an alkyl silicate or its oligomer is introduced onto the surface of the substrate, forming a composite oxide film of the metal and silicon that constitute the metal substrate. Then, in a subsequent drying process, a silane film composed of the organosilane compound is formed, in which the organosilane compound and the composite oxide film are chemically bonded. In this way, a surface-treated metal material can be obtained that has excellent adhesive bonding properties, excellent corrosion resistance, and is resistant to deterioration in adhesive strength even when exposed to a high-temperature, humid environment, and has excellent adhesion durability. Furthermore, the use of the metal treatment solution allows surface treatment with the alkyl silicate or its oligomer and surface treatment with the organosilane compound to be performed in a single step, thereby simplifying the production of surface-treated metal materials with excellent adhesion durability and reducing capital investment and production costs.

[0057] The pH of the metal treatment solution is preferably 2 or higher and 7 or lower. A pH higher than 7 is undesirable because it can lead to excessive polymerization of the alkyl silicate or its oligomer, reducing the storage stability of the solution. Furthermore, as the polymerization of the alkyl silicate or its oligomer progresses, the resulting silane coating becomes thicker, causing internal breakdown of the silane coating when stress is applied, making it impossible to achieve high adhesive strength. Therefore, the pH of the metal treatment solution is preferably 7 or lower, and more preferably 6 or lower from the standpoint of alkyl silicate stability.

[0058] On the other hand, if the pH of the metal treatment solution is lower than 2, the surface of the substrate will be dissolved vigorously, resulting in an uneven silane coating, making it difficult to achieve stable adhesive performance. Therefore, the pH of the metal treatment solution is preferably 2 or higher, and, taking into account reactivity with the metal oxide coating, more preferably 3 or higher. The pH of the metal treatment solution can be adjusted appropriately by adding an acid such as hydrochloric acid, sulfuric acid, nitric acid, or acetic acid.

[0059] The concentration of alkyl silicate or its oligomer in the metal treatment solution is preferably 0.005% by mass or more and less than 1% by mass. If the concentration of alkyl silicate or its oligomer in the metal treatment solution is 1% by mass or more, the silane coating formed may become thick and its strength may decrease. Therefore, the concentration of alkyl silicate or its oligomer 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.

[0060] On the other hand, if the concentration of alkyl silicate or its oligomer in the metal treatment solution is less than 0.005% by mass, the concentration of alkyl silicate or its oligomer is too low, making it impossible to form a sufficient composite oxide film of the metal and silicon that constitutes the metal substrate, and sufficient adhesion durability may not be obtained. Therefore, the concentration of alkyl silicate or its oligomer 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.

[0061] 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 silane film formed may become thick and its strength may decrease. Furthermore, the stability of the solution may also decrease. 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.

[0062] 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 is too low, making it impossible to form a sufficient surface treatment film containing the organosilane compound, and sufficient adhesion durability cannot be obtained. 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.

[0063] When the mass of alkyl silicate or its oligomer contained as the silane compound in the metal treatment solution is X and the mass of the hydrolyzate or polymer of the organosilane compound is Y, the ratio of X to Y is preferably 4:1 to 1:4. Furthermore, the ratio of X to Y is more preferably 2:1 to 1:2. In order to control the polymerization of these substances and stabilize the metal treatment solution, the metal treatment solution preferably contains 10% by mass or less of an acid relative to the total mass of the silane compound.

[0064] In order to achieve sufficient adhesion durability in a silane coating composed of an alkyl silicate or its oligomer and a hydrolyzate or polymer of an organic silane compound, it is preferable to adjust the coating amount to an optimum range. 2 If the coating amount of the silane coating is less than 20 mg / m, the metal surface cannot be sufficiently covered with the coating, and it may be difficult to obtain the desired adhesion durability. 2 If the coating amount of the silane coating exceeds 0.1 mg / m, the silane coating becomes bulky, resulting in insufficient adhesion of the silane coating to the metal substrate, which may cause breakage originating from the silane coating, making it difficult to obtain the desired adhesive strength. 2 More than 20mg / m 2 It is preferable to keep it below 0.5 mg / m 2 More than 15mg / m 2By preparing a metal treatment solution while designing the ratio of X to Y in the silane compound in the metal treatment solution and the content thereof within the above range, a preferred coating amount of the silane coating can be achieved.

[0065] The type of alkyl silicate or its oligomer contained in the metal treatment solution is not particularly limited, but silicates, tetraalkoxy orthosilicates, or their oligomers are preferred from the viewpoint of not producing by-products that may cause corrosion of the coating or deterioration of the adhesive resin after the reaction. Among these, tetraethyl orthosilicate (TEOS) or its polymers (oligomers) are preferred because they are neutral and do not leave any alkali residue after the silane coating is formed. Polymers include oligomers. Here, the alkyl silicates or their oligomers may be used alone or in combination of two or more.

[0066] The type of organosilane compound contained in the metal treatment solution is not particularly limited, but the organosilane compound may include a silane compound having multiple hydrolyzable trialkoxy groups in the molecule, its hydrolysate, or a polymer thereof. Silane compounds having multiple hydrolyzable trialkoxy groups in the molecule not only form dense siloxane bonds by self-polymerization, but also have high reactivity with metal oxides, forming chemically stable bonds, thereby further improving the wet durability of the silane coating. Furthermore, silane coatings have high mutual solubility with machine oils such as processing oil and press oil, and organic compounds such as adhesives. Therefore, even if machine oils such as processing oil and press oil adhere to the coating, the effects of these oils can be mitigated, thereby preventing a decrease in adhesion durability due to oil application. The type of the silane compound is not particularly limited, but from an economical standpoint, a silane compound having two hydrolyzable trialkoxysilyl groups in the molecule (bissilane compound) is preferred, and examples thereof include bistrialkoxysilylethane, bistrialkoxysilylbenzene, bistrialkoxysilylhexane, bistrialkoxysilylpropylamine, and bistrialkoxysilylpropyltetrasulfide. In particular, from the standpoints of versatility, economical efficiency, and aqueous solution stability, it is preferable to use bistrialkoxysilylethane, and it is even more preferable to use bistriethoxysilylethane (BTSE). Here, the organic silane compound may be used alone or in combination of two or more.

[0067] In addition, the organic silane compound may contain a silane coupling agent having a reactive functional group capable of chemically bonding with an organic resin component, its hydrolyzate, or its polymer.For example, a silane coupling agent having a reactive functional group such as an amino group, an epoxy group, a methacrylic group, a vinyl group, or a mercapto group can be used alone or in combination with a silane compound to form a chemical bond between the coating and the resin, thereby further improving adhesion durability.The functional group of the silane coupling agent is not limited to those described above, and silane coupling agents having various functional groups can be appropriately selected and used depending on the adhesive resin used. Specific preferred examples of the silane coupling agent include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(N-aminoethyl)-aminopropyltrimethoxysilane, 3-(N-aminoethyl)-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, etc. Here, as the silane coupling agent, only one type may be used alone, or two or more types may be used in combination.

[0068] In this embodiment, if the metal treatment solution contains particulate inorganic compounds with a diameter of 10 nm or more (hereinafter simply referred to as "particulate inorganic compounds"), an additional process such as water washing to remove the silane coating is required after the silane coating is formed. Furthermore, the silane coating formed may be thick, potentially reducing the adhesive strength and durability. Therefore, it is preferable that the metal treatment solution is substantially free of particulate inorganic compounds. Note that "the metal treatment solution is substantially free of particulate inorganic compounds" does not necessarily mean that the solution is completely free of particulate inorganic compounds; it is acceptable for the solution to contain particulate inorganic compounds at an impurity level. Specifically, it is preferable that the content of particulate inorganic compounds be regulated to 0.05% by mass or less relative to the total amount of the metal treatment solution. Examples of particulate inorganic compounds include sols of inorganic oxides such as silica and alumina. The diameter of the particulate inorganic compounds refers to the diameter measured by observing the solid content of the treatment solution after drying using a transmission electron microscope (TEM) or by measuring the diluted treatment solution using a liquid particle counter.

[0069] In addition to the alkyl silicate or its oligomer, and the organosilane compound, the metal treatment solution may further contain, as necessary, one or more stabilizers, adjuvants, etc. For example, the metal treatment solution may contain, as a stabilizer, an organic compound such as a carboxylic acid having 1 to 4 carbon atoms, e.g., formic acid or acetic acid, or an alcohol having 1 to 4 carbon atoms, e.g., methanol or ethanol.

[0070] The metal treatment solution may be prepared, for example, by the following preparation method, but is not limited thereto. First, an organosilane compound and a small amount of acetic acid as a catalyst are added to a mixture of water and an alcohol such as ethanol, and the organosilane compound is sufficiently hydrolyzed to form an aqueous solution of the organosilane compound. Next, an aqueous solution of an alkyl silicate or its oligomer is prepared using a similar method, and these two solutions are mixed and then diluted with water to a predetermined silane compound concentration, thereby preparing the metal treatment solution. Furthermore, since alkyl silicates and their oligomers are basic and prone to polymerization, when a basic compound is used 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 oligomer when the solutions are mixed.

[0071] (Adhesive resin layer) In the present invention, the resin constituting the adhesive resin layer is not particularly limited, and adhesive resins that have conventionally been used to bond titanium or titanium alloy materials, such as epoxy resins, urethane resins, nitrile resins, nylon resins, acrylic resins, etc. The thickness of the adhesive resin layer is also not particularly limited, but from the viewpoint of improving adhesive strength, it is preferably 10 to 500 μm, and more preferably 50 to 400 μm.

[0072] [Method of manufacturing the bonded body] The manufacturing method of the bonded body according to this embodiment is a manufacturing method of a bonded body including the above-described surface-treated metal material. Specifically, the method includes a bonding step of bonding a first member and a second member via an adhesive resin layer, where at least one of the first member and the second member is the above-described surface-treated metal material. In the bonding step, the first member and the second member are bonded by arranging the silane coating of the surface-treated metal material and the adhesive resin layer in contact with each other.

[0073] 1C, for example, an adhesive resin layer may be formed in the region R where the silane coating 4 is formed by the method described in the adhesive resin layer forming step, and the first member (not shown) may be joined so as to come into contact with this adhesive resin layer. The method for forming the adhesive resin layer is not particularly limited, but as described above, an adhesive sheet made of an adhesive resin material may be used, or the adhesive resin material may be sprayed or applied to the surface of the silane coating.

[0074] According to this embodiment, since the surface-treated metal material can be easily produced at low cost as described above, a bonded body with excellent adhesive durability can be easily produced at low cost. In this embodiment, only one of the first member and the second member may be a surface-treated metal material produced by the [method for producing a surface-treated metal material], or both may be surface-treated metal materials produced by the [method for producing a surface-treated metal material]. When only one of the first member and the second member is the surface-treated metal material, the other member (the second member) may be a metal member that has not been surface-treated, a resin molded product that has not been surface-treated, or the like. As the surface-treated metal member, various metal members can be used, such as a titanium or titanium alloy member, an aluminum or aluminum alloy member, a stainless steel member, or a copper or copper alloy member.

[0075] When both the first and second members are surface-treated metal materials manufactured by the above-mentioned "Method for Manufacturing a Surface-Treated Metal Material," the metal substrates constituting the surface-treated metal materials may be the same or different. For example, the first and second members may each be surface-treated metal materials using various metal substrates such as titanium or titanium alloy, aluminum or aluminum alloy, stainless steel, copper or copper alloy, etc.

[0076] Furthermore, as the resin molded body, for example, a fiber-reinforced plastic molded body 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 fiber reinforced plastic (ZFRP) can be used. By using these fiber-reinforced plastic molded bodies, it is possible to reduce the weight of the joined body while maintaining a certain level of strength.

[0077] In addition to the above-mentioned fiber-reinforced plastics, non-fiber-reinforced engineering plastics such as polypropylene (PP), acrylic-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 the resin molded body.

[0078] In the above-described embodiment, an adhesive resin layer for producing a bonded structure is formed on a surface-treated metal material, but in the present invention, as described above, a coating film may be formed by applying a paint to at least a portion of the silane coating. In the surface-treated metal material produced by the production method according to this embodiment, the adhesion between the metal substrate and the silane coating is excellent, and the bonding between the silane coating and the paint is also excellent, so that the effect of preventing peeling of the paint can be obtained. [Example]

[0079] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples and can be practiced with modifications within the scope of the present invention, all of which are included in the technical scope of the present invention. In addition, the various production conditions below are examples, and the present embodiment is not limited to the following conditions.

[0080] [Manufacturing surface-treated metal materials] <Preparing the substrate> First, plates made of various metal materials were cut to a length of 100 mm and a width of 25 mm to prepare two metal substrates for each test condition. The types of metal materials are listed below. Aluminum alloy (JIS standard A7075): Plate thickness 3.8 mm Aluminum alloy (JIS standard A5052): Plate thickness 2mm Pure titanium (JIS standard type 1): thickness 1.2 mm Stainless steel (JIS standard SUS304): Plate thickness 1mm

[0081] <Blast treatment process> Next, the evaluation range of the metal substrate was set to 10 mm from the longitudinal end and 25 mm in the width direction, and all substrates were subjected to dry or wet blasting treatment in the evaluation range, followed by rinsing with water for 1 minute. The treatment conditions for the blasting treatment were as follows:

[0082] (Dry blasting conditions) Dry blasting equipment: Shot blasting equipment (NAB-3K) manufactured by Nissanki Co., Ltd. Abrasive material: Showa Denko Co., Ltd. White Morundum abrasive grain: WA#150 Blast pressure: 0.7 (MPa)

[0083] (Wet blasting conditions) Wet blasting equipment: Maco Corporation BABY Blast II (Model: MBBII-25) Abrasive material: Showa Denko Co., Ltd. Abrasive grain white Morundum: WA#150, WA#320, Air pressure: 0.12 MPa Gun movement speed 10mm / sec

[0084] <Adhesion process> Each metal substrate was then immersed in the metal treatment solution shown below for 10 seconds at room temperature and then removed. A silane coating was formed by drying for 60 seconds at 100°C in a blast oven, yielding a surface-treated metal material. The manufacturing conditions for each surface-treated metal material are shown in Table 1 below.

[0085] (metal treatment solution) Bistriethoxysilylethane (BTSE) 0.1g Tetraethyl orthosilicate (TEOS) 0.1g Ethanol 2.0g Acetic acid 0.001g Water 97.8g

[0086] [Manufacturing of joints] Then, two metal substrates were bonded together with an adhesive to obtain a bonded assembly. Fig. 2A is a side view showing the shape of the bonded assembly, and Fig. 2B is a plan view thereof. As shown in Figs. 2A and 2B, an adhesive resin layer 35 was formed on the surface of the surface-treated metal material 31b (second member) in the evaluation range, and a surface-treated metal material 31a (first member) having the same configuration as the surface-treated metal material 31b was placed on top of the adhesive resin layer 35. The overlap length was 10 mm, and the surface-treated metal material 31a and the surface-treated metal material 31b were placed so that only a region 10 mm from the end of each was overlapped.

[0087] In this example, a silane coating was formed on both the surface-treated metal material 31a and the surface-treated metal material 31b within the evaluation range. The 10 mm × 25 mm areas where the silane coating was formed were then placed facing each other via an adhesive resin layer 35. A thermosetting structural epoxy resin adhesive was used as the adhesive resin layer material. A small amount of glass beads (particle size 250 μm) was added to the adhesive resin material to adjust the thickness of the adhesive resin layer 35 to 250 μm. After being stacked and placed as described above, the materials were dried at room temperature for 30 minutes and then heated at 180°C for 30 minutes for thermal curing. The resulting mixture was then left to stand at room temperature for 24 hours to produce a bonded assembly.

[0088] [Evaluation of zygotes] <Deterioration test> A degradation test was carried out on some of the resulting bonded bodies to evaluate their adhesive durability. The degradation test consisted of immersing the bonded bodies in a 5% NaCl solution at 40°C.

[0089] <Tensile test> A tensile test was performed on the resulting bonded structure to evaluate its adhesiveness. The tensile conditions were as follows: both ends of the bonded structure were pulled in the direction indicated by the arrows in FIG. 2A at a tensile speed of 50 mm / min until fracture. The fracture surfaces of the surface-treated metal material 31a (first member) and the surface-treated metal material 31b (second member) were then 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 member) and the area of ​​the contact surface between the surface-treated metal material 31a and the adhesive resin layer (adhesion area of ​​the first member) 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 member) and the area of ​​the contact surface between the surface-treated metal material 31b and the adhesive resin layer (adhesion area of ​​the second member) were also measured. The cohesive failure rate was then calculated using the following formula (2). The conditions of the degradation test and the calculation results of the cohesive failure rate are shown in Table 1 below.

[0090] Cohesive failure rate (%) = 100 - {(interfacial peel area of ​​first component / adhesive area of ​​first component) × 100 + (interfacial peel area of ​​second component / adhesive area of ​​second component) × 100} (2)

[0091] [Table 1]

[0092] As shown in Examples 1 to 5 in Table 1 above, regardless of the type of metal substrate, a silane film could be formed simply by carrying out a blast treatment process as a pretreatment. Therefore, the burden on the environment could be reduced, and surface-treated metal materials could be produced easily at low cost. In addition, the formed silane film had excellent adhesion to the metal substrate, The adhesive durability was also excellent. Furthermore, because a silane film with excellent performance was formed, the adhesive resin layer had excellent bonding strength and showed an excellent cohesive failure rate. [Explanation of symbols]

[0093] 1 Metal base material 2 abrasive grains 3. Metal treatment solutions 4 Silane coating 10 Surface-treated metal materials 31a Surface-treated metal material (first component) 31b Surface-treated metal material (second component) 35 Adhesive resin layer

Claims

1. A method for producing a surface-treated metal material having a silane coating provided on at least a portion of a surface of a metal substrate, wherein the metal substrate is pure aluminum, an aluminum alloy, pure titanium, a titanium alloy, copper, or a copper alloy; a blasting step of blasting at least a part of the surface of the metal base material without performing a degreasing step and a step of etching an oxide film with an acid solution; a coating step of coating the surface of the metal substrate that has been subjected to the blast treatment with a metal treatment solution containing a silane compound; a drying step of drying the metal substrate coated with the metal treatment solution to form a silane coating, wherein a cleaning step is not performed after the drying step, A method for producing a surface-treated metal material, characterized in that the metal treatment solution contains a silane compound in an amount of 0.01 mass% or more and 1 mass% or less, and the silane compound includes an alkyl silicate or an oligomer thereof, and a hydrolyzate of a bissilane compound or a polymer thereof.

2. Between the blasting step and the deposition step, a water washing step of washing the metal base material that has been subjected to the blast treatment with water, 2. The method for producing a surface-treated metal material according to claim 1, wherein the coating step is carried out in a state where water from the water-washing step is still attached to the surface that has been subjected to the blasting treatment.

3. 2. The method for producing a surface-treated metal material according to claim 1, wherein the time from the end of the blasting step to the start of the deposition step is within 8 hours.

4. 2. The method for producing a surface-treated metal material according to claim 1, wherein the content of the particulate inorganic compound having a diameter of 1 nm or more is 0.05 mass % or less relative to the total mass of the metal treatment solution.

5. The deposition step includes: a coating step of applying the metal treatment solution to the metal substrate, thereby depositing the metal treatment solution on the surface of the metal substrate; a recovery step of recovering excess metal treatment solution generated by the application step, 2. The method for producing a surface-treated metal material according to claim 1, wherein the excess metal treatment solution is reused in the coating step when producing another surface-treated metal material.

6. The deposition step includes:

2. The method for producing a surface-treated metal material according to claim 1, further comprising an immersion step of immersing the metal substrate in the metal treatment solution to coat the surface of the metal substrate with the metal treatment solution.

7. 7. The method for producing a surface-treated metal material according to claim 1, wherein an adhesive or paint is applied directly to the surface of the silane coating.

8. the surface-treated metal material has a functional layer in contact with the surface of the silane coating, the functional layer is an adhesive resin layer or a coating film formed by the adhesive or paint, After the drying step, 8. The method for producing a surface-treated metal material according to claim 7, further comprising a functional layer forming step of forming the functional layer on the surface of the silane coating.

9. A method for producing a joined body including a surface-treated metal material produced by the production method according to any one of claims 1 to 6, a joining step of joining a first member and a second member via an adhesive resin layer, At least one of the first member and the second member is the surface-treated metal material, A method for manufacturing a joined body, characterized in that in the joining step, the silane coating of the surface-treated metal material and the adhesive resin layer are arranged to be in contact with each other, thereby joining the first member and the second member.

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