Resin-metal joined body and method for producing same

Abstract

With respect to a resin-metal joined body in which a resin material is directly joined to a metal material without the use of, e.g., an adhesive or rivet fastening, the present invention provides: a long-life resin-metal joined body for which separation between the resin material and the metal material, damage to the resin material, and the like are effectively suppressed; and a simple and efficient method for producing this resin-metal joined body. The resin-metal joined body according to the present invention is a resin-metal joined body in which a resin plate and a metal plate are stacked, and is characterized in that: the metal plate has a length and / or a width larger than that of the resin plate; a direct joining interface, at which the metal plate and the resin plate are directly joined, is formed at an overlapping surface between the resin plate and the metal plate; and the resin-metal joined body has a hemmed section in which an end part of the metal plate is bent.

Description

Resin-metal bonded body and its manufacturing method

[0001] The present invention relates to a resin-metal bonded body in which a resin material and a metal material are directly bonded to each other, and a method for producing the same.

[0002] Conventionally, adhesives have been used to join resin materials together, and adhesives or rivets have been used to join resin and metal materials. When adhesives are used, the joining is achieved by physical or chemical adsorption, while when rivets are used, the joining is achieved by physical fastening with the rivet.

[0003] However, when adhesives are used, the joining strength is significantly affected by the condition of the joined surfaces, and there are cases where sufficient joining strength cannot be obtained both when joining resin materials together and when joining resin materials and metal materials. Furthermore, when riveting is used, the parts become larger and heavier depending on the size and weight of the fastening part, and the degree of freedom in design is reduced, so the parts that can be used with rivets are limited.

[0004] In response to this, inventors have proposed a method for directly joining a resin material and a metal material. For example, Patent Document 1 (JP 2018-103548 A) discloses a metal-resin joining method for directly joining a metal material and a resin material, the method comprising: a first step of forming a new surface on the metal material by electrolytic treatment using a reducing carboxylic acid and coating the new surface with the carboxylic acid to obtain a carboxylic acid-coated metal material; a second step of overlapping the resin material and the carboxylic acid-coated metal material to form a joining interface; a third step of heating the joining interface to a temperature equal to or higher than the glass transition temperature of the resin material to remove water from the joining interface, generating carboxyl groups through decomposition of the resin material, and removing the carboxylic acid to expose the new surface on the surface of the carboxylic acid-coated metal material; and a fourth step of cooling the joining interface to a temperature below the glass transition temperature to form a joint by bonding the carboxyl groups to the new surface.

[0005] In the metal-resin joining method described in Patent Document 1, various metal materials and resin materials can be easily and directly joined by chemically bonding the newly formed surface of the metal material with carboxyl groups derived from the resin material generated by thermal decomposition.

[0006] In addition, Patent Document 2 (JP 2019-123153 A) discloses a method for directly joining one workpiece to another workpiece, wherein the one workpiece is a fluororesin material, and the method comprises the following steps: a first step of applying a mixed solution containing sodium to a surface of the one workpiece to be joined, and then irradiating the surface with the mixed solution with a laser; a second step of bringing the other workpiece to be joined into contact with the surface with the mixed solution applied to form a joining interface; and a third step of raising the temperature of the joining interface by irradiating with a laser.

[0007] In the bonding method of fluororesin described in Patent Document 2, the C—F bond of the fluororesin is separated by laser irradiation, and sodium, which has a high bonding affinity with fluorine, is bonded to fluorine, thereby improving the bondability of the inactive fluororesin, which has a stable molecular structure.

[0008] Furthermore, Patent Document 3 (WO 2021 / 230025) discloses a method for directly bonding a metal material and a thermoplastic resin material, which comprises a first step of irradiating the surface of the metal material with a pulsed laser in an oxidizing atmosphere to form a surface-modified region, a second step of contacting the thermoplastic resin material with the surface-modified region to form a bonded interface, and a third step of raising the temperature of the bonded interface by laser irradiation to achieve bonding. In the first step, a metal oxide particle cluster is formed in which metal oxide particles having a particle size of 5 to 500 nm are continuously bonded to the surface modified region, and the maximum height (Sz) of the surface of the metal oxide particle cluster is 50 nm to 3 μm. A direct metal-thermoplastic resin bonding method is disclosed.

[0009] In the direct metal-thermoplastic resin bonding method described in Patent Document 3, the dissociation of the molecular bonds of the thermoplastic resin material in the third step is promoted by the metal oxide particle clusters, making it possible to efficiently obtain a strong bonded joint.

[0010] JP 2018-103548 A JP 2019-123153 A International Publication No. 2021 / 230025

[0011] By using each of the joining methods described in Patent Documents 1 to 3, it is possible to directly join a resin material and a metal material. However, when a resin-metal direct joining interface is formed at the overlapping surface of the resin material and the metal material, residual shear stress inevitably occurs at the resin-metal direct joining interface due to the difference in expansion and contraction behavior between the resin material and the metal material.

[0012] In particular, there is a risk of the resin material peeling off from the metal material at both ends of the linear resin-metal direct bonded interface. If this phenomenon is significant, the resin material and the metal material may partially peel off during the manufacturing process of the resin-metal bonded body, and a good resin-metal bonded body may not be obtained. Furthermore, the residual shear stress at the resin-metal direct bonded interface may shorten the life of the resin-metal bonded body (due to damage to the resin material, peeling from the metal material, etc.).

[0013] In view of the problems in the conventional techniques as described above, an object of the present invention is to provide a resin-metal joined body in which a resin material and a metal material are directly joined without using adhesives, rivets, or the like, in which peeling between the resin material and the metal material, damage to the resin material, and the like are effectively suppressed, and to provide a simple and efficient method for producing the same.

[0014] In order to achieve the above object, the present inventors have conducted extensive research into the structure of resin-metal bonded bodies, and as a result have found that it is effective to provide a hemmed portion in which the end of the metal plate is bent in a resin-metal bonded body in which a resin plate and a metal plate are directly bonded, and have arrived at the present invention.

[0015] That is, the present invention provides a resin-metal joined body in which a resin plate and a metal plate are laminated together, wherein the metal plate is larger in length and / or width than the resin plate, a direct joining interface where the metal plate and the resin plate are directly joined is formed at the overlapping surface between the resin plate and the metal plate, and a hemmed portion is formed by folding an end of the metal plate.

[0016] Hemming is a process in which the edge of a plate is bent 180 degrees and crushed flat. Conventional hemming processes aim to ensure safety, reinforce, and improve appearance by trimming the edges of structural parts. Patent Document 1 also discloses a technology for preventing peeling at the bonded interface by providing a resin-metal direct bonded portion at the hemmed portion where a resin plate is sandwiched between metal plates.

[0017] In contrast, in the resin-metal bonded body of the present invention, a direct bond interface where the metal plate and the resin plate are directly bonded is formed at the overlapping surfaces of the resin plate and the metal plate, and a hemmed portion is formed by bending the end of the metal plate. That is, the resin-metal bonded body obtained by the metal-resin bonding method of Patent Document 1 and the resin-metal bonded body of the present invention differ in the position of the resin-metal direct bonded portion and the purpose of the hemming.

[0018] In the resin-metal bonded body of the present invention, damage to the resin plate, peeling of the resin plate from the metal plate, and the like caused by residual stress applied to the direct bond interface formed on the overlapping surfaces of the resin plate and the metal plate are suppressed by the hemmed portion formed on the end portion of the resin-metal bonded body, thereby extending the life of the resin-metal bonded body.

[0019] Furthermore, since the hemmed portion is more convex than the surface of the resin plate, for example, when soil or sand or the like continuously contacts and slides against it, the surface of the hemmed portion (metal plate) wears preferentially, thereby suppressing wear of the resin plate, which has a relatively low hardness. Furthermore, in the resin-metal joined body of the present invention, the resin plate and the metal plate are directly joined at the overlapping surfaces, so that even if the hemmed portion is damaged, the effect on the entire resin-metal joined body can be minimized.

[0020] In addition, when it is necessary to attach the resin-metal joined body to a suitable metal substrate, the resin-metal joined body and the metal substrate can be welded together using the hemmed portion (metal plate) as a weld allowance. In the resin-metal joined body of the present invention, the resin plate and the metal plate are directly joined at the overlapping surfaces, so that when the hemmed portion is used as a weld allowance, there is no need to consider the thermal effect on the joint during welding.

[0021] In the resin-metal bonded body of the present invention, the resin plate is preferably a fluororesin, which has excellent chemical resistance, abrasion resistance, flame retardancy, water and oil repellency, and characteristic electrical properties such as low relative dielectric constant and dielectric loss tangent, making the resin-metal bonded body suitable for use in industries related to medical devices, foods, pharmaceuticals, etc.

[0022] In the resin-metal bonded body of the present invention, the resin plate is preferably polytetrafluoroethylene (PTFE). Polytetrafluoroethylene has a molecular structure in which carbon atoms and fluorine atoms are bonded in a linear chain, and the atomic arrangement within the molecule is tight and symmetrical, resulting in extremely small charge polarization. Due to its molecular structure, polytetrafluoroethylene is particularly chemically stable among fluororesins, and has excellent characteristics such as non-adhesiveness, low friction, heat resistance, chemical resistance, and electrical properties, making the resin-metal bonded body more suitable for use in industries related to medical devices, food, pharmaceuticals, etc.

[0023] In the resin-metal bonded body of the present invention, the metal plate is preferably any one of aluminum, aluminum alloy, titanium, titanium alloy, and steel. These metal materials and the resin material can form a high-strength direct bond interface. In addition, the use of aluminum and aluminum alloy materials allows for the realization of a lightweight resin-metal bonded body at a relatively low cost, the use of titanium and titanium alloy materials allows for the realization of a lightweight resin-metal bonded body with excellent corrosion resistance, and the use of steel materials allows for the realization of an inexpensive resin-metal bonded body with excellent mechanical properties.

[0024] In the resin-metal bonded body of the present invention, the thickness of the resin plate is preferably 0.25 to 5 mm. By making the thickness of the resin plate 0.25 mm or more, deterioration of properties such as slip resistance due to wear and friction of the resin plate over long periods of use can be suppressed, and by making the thickness 5 mm or less, increases in weight and cost of the resin-metal bonded body due to the resin plate can be suppressed.

[0025] Furthermore, in the resin-metal bonded body of the present invention, it is preferable that the resin plate and the metal plate are joined or adhered to each other at the hemmed portion. In the resin-metal bonded body of the present invention, the resin plate and the metal plate are integrated by a direct joint at the overlapping portion, but by joining or adhering the resin plate and the metal plate at the hemmed portion, the bonded state between the resin plate and the metal plate becomes stronger, thereby imparting high reliability to the resin-metal bonded body and further extending its lifespan.

[0026] The present invention also provides a method for producing a resin-metal bonded body of the present invention, comprising: a first step of laminating a resin plate and a metal plate to form a joining surface; a second step of forming a direct joining interface between the resin plate and the metal plate on the joining surface; and a third step of hemming an end portion of the metal plate.

[0027] In the second step, residual stress in the shear direction is applied to the direct bond interface formed at the overlapping surfaces of the resin plate and the metal plate. In response to this, by hemming the edge of the metal plate in the third step, it is possible to suppress peeling of the resin plate from the metal plate due to the residual stress and neutralize the residual stress.

[0028] The method for directly joining the resin plate and the metal plate in the second step is not particularly limited as long as it does not impair the effects of the present invention. For example, the joining methods described in Patent Documents 1 to 3 above can be suitably used.

[0029] The position, shape, and size of the hemming formed on the end of the metal plate may be appropriately adjusted depending on the position, shape, and size of the direct bonding interface between the resin plate and the metal plate at the overlapping surfaces, the shape, size, and desired mechanical properties of the resin-metal bonded body, etc., but it is preferable to optimize the hemming to take into account the residual stress applied to the direct bonding interface.

[0030] In addition, in the method for producing a resin-metal bonded body of the present invention, it is preferable that, as a preliminary treatment for the first step, a pulsed laser is irradiated onto the surface of the metal plate in an oxidizing atmosphere to form a surface-modified region, the surface-modified region and the resin plate are brought into contact with each other in the first step, and the temperature of the overlapping surfaces is raised by laser irradiation to form the direct bonding interface in the second step.

[0031] In the first step, a pulsed laser is irradiated onto the surface of the metal plate in an oxidizing atmosphere, thereby forming oxide clusters composed of fine oxide particles on the surface. The oxide clusters on the surface of the metal plate can promote dissociation of C-F bonds in fluororesin materials and C-H bonds, C-C bonds, C=C bonds, and C-N bonds in other thermoplastic resin materials when the resin plate is heated in the second step. The reason for this promotion of dissociation is not entirely clear, but it is thought that metal oxide particles with an appropriate curvature (energy state) exhibit a so-called catalytic effect. Furthermore, functional groups such as carboxyl groups generated by the dissociation bond with metal elements contained in the metal material, forming a strong resin-metal direct bonding interface.

[0032] Furthermore, the method for producing a resin-metal bonded body of the present invention preferably includes a fourth step of joining or adhering the resin plate and the metal plate at the hemmed portion. Since stress that would cause separation of the contact surfaces of the resin plate and the metal plate is not applied at the hemmed portion, joining or adhering the resin plate and the metal plate at the hemmed portion can improve the reliability of the resin-metal bonded body and effectively prevent the resin plate from separating from the metal plate.

[0033] According to the resin-metal bonded body and the manufacturing method thereof of the present invention, a resin material and a metal material are directly bonded to each other without using adhesives, rivets, or the like, and it is possible to provide a resin-metal bonded body having a long life in which peeling between the resin material and the metal material, damage to the resin material, and the like are effectively suppressed, and a simple and efficient manufacturing method thereof can be provided.

[0034] FIG. 1 is a schematic diagram showing an example of a resin-metal bonded body of the present invention. FIG. 2 is a schematic cross-sectional view of a resin-metal bonded body 1 in which a hemmed portion is bonded or adhered. FIG. 3 is a schematic diagram showing an example of a direct bond interface 6 formed in a resin-metal bonded body of the present invention. FIG. 4 is a process diagram of a method for producing a resin-metal bonded body of the present invention. FIG. 5 is a photograph of the appearance of a resin-metal bonded body obtained as an example. FIG. 6 is a photograph of the appearance of an apparatus used in a scratch test. FIG. 7 is a photograph of the appearance of an example resin-metal bonded body and a comparative resin-metal bonded body after completion of a scratch test. FIG. 8 is a photograph of the appearance showing the change over time of the surface of a fluororesin plate with an increase in the number of sliding cycles.

[0035] Representative embodiments of the resin-metal bonded body and its manufacturing method of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited to these. In the following description, the same or corresponding parts will be designated by the same reference numerals, and duplicated explanations may be omitted. Furthermore, since the drawings are intended to conceptually explain the present invention, the dimensions of the components shown and their ratios may differ from the actual dimensions.

[0036] 1. Resin-Metal Bonded Body Fig. 1 is a schematic diagram showing an example of a resin-metal bonded body of the present invention. Fig. 1 shows a plan view and a cross-sectional view from the resin plate 2 side. The resin-metal bonded body 1 is a resin-metal bonded body in which a resin plate 2 and a metal plate 4 are laminated together, and the metal plate 4 is longer and / or wider than the resin plate 2. A direct bond interface 6 where the metal plate 4 and the resin plate 2 are directly bonded is formed at the overlapping surface between the resin plate 2 and the metal plate 4, and a hemmed portion 8 where an end of the metal plate 4 is bent.

[0037] 1, the position of the direct bonded interface 6 is indicated by a dotted line. The position, shape, and size of the direct bonded interface 6 are not particularly limited as long as they do not impair the effects of the present invention, and may be appropriately adjusted depending on the types, shapes, and sizes of the resin plate 2 and the metal plate 4, the manner of use of the resin-metal bonded body 1, and the like. For example, when a rectangular resin-metal bonded body 1 is to be obtained, an appropriate number of linear direct bonded interfaces 6 may be formed parallel to the long sides and / or short sides.

[0038] Furthermore, in the resin-metal bonded body 1, the vicinity of both ends of the direct bond interface 6 is constrained by the hemmings 8. This effectively prevents damage to the resin plate 2 and separation of the resin plate 2 and the metal plate 4, even when residual shear stress is applied to the direct bond interface 6. The position, shape, and size of the hemmings 8 may be adjusted as appropriate depending on the shape and size of the direct bond interface 6 and the resin-metal bonded body 1. However, when a linear direct bond interface 6 is formed as shown in FIG. 1 , it is preferable to design the hemmings 8 so that both ends of the direct bond interface 6 are sufficiently constrained. In this case, the ends of the direct bond interface 6 may be located within or outside the hemmings 8. Overlapping the ends of the direct bond interface 6 with the hemmings 8 can further improve the effect of suppressing peeling from the ends of the direct bond interface 6. On the other hand, by positioning the ends of the direct bond interface 6 outside the hemmings 8 as weld margins, the thermal effects on the direct bond interface 6 during welding can be reduced when the resin-metal bonded body 1 and the metal substrate are welded together.

[0039] The material of the resin plate 2 is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known thermoplastic resins can be used. Here, the resin plate 2 is preferably a fluororesin, and more preferably polytetrafluoroethylene. By using such a material for the resin plate 2, the resin-metal bonded body 1 can be imparted with good chemical resistance, abrasion resistance, flame retardancy, water and oil repellency, electrical properties, etc., and the resin-metal bonded body 1 can be suitably used in related industries such as medical devices, food products, pharmaceuticals, and construction machinery and tools for transporting earth and sand, etc.

[0040] The thickness of the resin plate 2 is preferably 0.25 to 5 mm. By making the thickness of the resin plate 2 0.25 mm or more, it is possible to suppress deterioration of properties such as slip resistance due to wear and friction of the resin plate 2 over long periods of use, and by making the thickness 5 mm or less, it is possible to suppress increases in weight and cost of the resin-metal bonded body 1 due to the resin plate 2. Here, the thickness of the resin plate 2 is more preferably 0.5 to 3 mm, and most preferably 0.75 to 2 mm.

[0041] The material of the metal plate 4 is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known metals can be used, but it is preferably any one of aluminum, aluminum alloy, titanium, titanium alloy, and steel. A high-strength direct bond interface 6 can be formed between the metal plate 4 made of these metals and the resin material 2. Additionally, the use of aluminum and aluminum alloy materials allows for a lightweight resin-metal joined body 1 to be realized at a relatively low cost. The use of titanium and titanium alloy materials allows for a lightweight resin-metal joined body 1 with excellent corrosion resistance. The use of steel materials allows for an inexpensive resin-metal joined body 1 with excellent mechanical properties.

[0042] Furthermore, the shapes and sizes of the resin plate 2 and the metal plate 4 are not particularly limited as long as they do not impair the effects of the present invention, but since it is necessary to fold back the end of the metal plate 4 to form the hemmed portion 8, the metal plate 4 before hemming is wider and / or longer than the resin plate 2.

[0043] 2 shows a schematic cross-sectional view of a resin-metal joined body 1 in which the resin plate 2 and the metal plate 4 are joined or adhered at the hemmed portion 8. At the hemmed portion 8, a joining or adhesion interface 10 is formed between the resin plate 2 and the metal plate 4. At the hemmed portion 8, no stress is applied in a direction that would cause the resin plate 2 and the metal plate 4 to peel off, so the resin plate 2 and the metal plate 4 can be firmly joined or adhered. Here, the method for joining or adhering the resin plate 2 and the metal plate 4 is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known joining or adhering methods can be used, but the joining methods described in Patent Documents 1 to 3 above can be suitably used.

[0044] If the resin plate 2 and the metal plate 4 are joined or adhered only at the hemmed portion 8 without forming a direct bond interface 6 where the metal plate 4 and the resin plate 2 are directly bonded at the overlapping surfaces of the resin plate 2 and the metal plate 4, the resin plate 2 and the metal plate 4 cannot be sufficiently adhered and fixed to each other. As a result, damage to the resin plate 2 and separation between the resin plate 2 and the metal plate 4 are likely to occur, and the life of the resin-metal joined body 1 cannot be extended.

[0045] As described above, the position, shape, and size of the direct bonded interface 6 are not particularly limited as long as they do not impair the effects of the present invention. A representative embodiment of the resin-metal bonded body of the present invention is shown in Fig. 1, but the direct bonded interface 6 may also be formed as shown in the plan view of Fig. 3.

[0046] 2. Manufacturing Method of Resin-Metal Bonded Body Figure 4 is a process diagram of the manufacturing method of the resin-metal bonded body of the present invention. The manufacturing method of the resin-metal bonded body of the present invention includes a first step (S01) of laminating the resin plate 2 and the metal plate 4 to form a mating surface, a second step (S02) of forming a direct bonding interface 6 between the resin plate 2 and the metal plate 4 on the mating surface, and a third step (S03) of hemming the edge of the metal plate 4. In addition, as an optional step, a fourth step (S04) of joining or adhering the resin plate 2 and the metal plate 4 at the hemmed portion 8 can be performed. Each step will be described in detail below.

[0047] (1) First Step (S01: Laminating Surface Forming Step) The first step (S01) is a step for laminating the resin plate 2 and the metal plate 4 together to form the laminating surface in order to form the direct bonding interface 6 in the second step (S02). Taking into consideration the hemming process in the third step (S03), it is necessary to adjust the positions of the resin plate 2 and the metal plate 4 so that the edge of the metal plate 4 is on the outside of the resin plate 2.

[0048] Furthermore, for example, when the temperature of the overlapping surfaces is raised by laser irradiation to form a direct bonding interface 6 in the second step (S02), it is preferable to irradiate the surface of the metal plate 4 with a pulsed laser in an oxidizing atmosphere as a preliminary treatment for the first step (S01) to form a surface-modified region.

[0049] The laser used in the preliminary treatment is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known lasers can be used, for example, a semiconductor laser that can efficiently heat the metal plate 4 can be suitably used. The irradiation energy of one pulse of the pulse laser is preferably 0.2 to 1.0 mJ. By setting the irradiation energy of one pulse of the pulse laser to 0.2 to 1.0 mJ, metal oxide particle clusters can be formed in the irradiated region in which metal oxide particles having particle sizes of 5 to 500 nm are continuously bonded together, and the maximum height (Sz) of the surface of the metal oxide particle clusters can be set to 50 nm to 3 μm.

[0050] Furthermore, when the resin plate 2 and the metal plate 4 are stacked, a heat-resistant glass plate or the like can be placed on the surface of one or both of the materials to be joined to fully restrain them, thereby making it possible to bring the materials into closer contact with each other and suppressing misalignment of the joining interface during laser irradiation in the second step (S02). Note that it is preferable to use heat-resistant glass that has excellent laser transparency.

[0051] When the resin plate 2 is made of a fluororesin, the type of the fluororesin is not particularly limited as long as it does not impair the effects of the present invention, and any conventionally known fluororesin can be used. Examples of the fluororesin include polytetrafluoroethylene (PTFE, melting point: 327°C), polychlorotrifluoroethylene (PCTFE, melting point: 220°C), polyvinylidene fluoride (PVDF, melting point: 151 to 178°C), polyvinyl fluoride (PVF, melting point: 203°C), tetrafluoroethylene-hexafluoropropylene copolymer (FEP, melting point: 250 to 275°C), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA, melting point: 302 to 310°C), and tetrafluoroethylene-ethylene Examples of suitable joining materials include tetrafluoroethylene copolymer (ETFE, melting point: 218 to 270°C), tetrafluoroethylene-perfluorodioxole copolymer (TFE / PDD), and chlorotrifluoroethylene-ethylene copolymer (ECTFE, melting point: 245°C). However, by using the joining methods described in Patent Documents 1 to 3, the resin plate 2 and the metal plate 4 can be directly joined, and a direct joining interface 6 with excellent high-temperature strength can be obtained without using an adhesive, so it is preferable to use polytetrafluoroethylene (PTFE, melting point: 327°C), which has a high melting point.

[0052] The metal plate 4 used as the material to be joined is not particularly limited as long as the effects of the present invention are not impaired, and various conventionally known metal materials can be used, for example, in addition to various steel materials, stainless steel, titanium, titanium alloys, aluminum, aluminum alloys, magnesium, magnesium alloys, copper, copper alloys, etc. can be used, but from the viewpoint of specific strength, aluminum, aluminum alloys, titanium, and titanium alloys are preferred, and from the viewpoint of corrosion resistance, etc., stainless steel, titanium, and titanium alloys are preferred. Also, from the viewpoints of cost and mechanical properties, steel materials are preferred.

[0053] (2) Second Step (S02: Direct Bonding Interface Forming Step) The second step (S02) is a step for forming the direct bonding interface 6 by raising the temperature of the overlapping surfaces by laser irradiation.

[0054] In the second step (S02), if the resin plate 2 is transparent, it is preferable to irradiate the resin plate 2 with a laser from the resin plate 2 side, and if the resin plate 2 is opaque, it is preferable to irradiate the resin plate 2 with a laser from the metal plate 4 side. By irradiating the resin plate 2 with a laser from the resin plate 2 side when the resin plate 2 is transparent, or by irradiating the resin plate 2 with a laser from the metal plate 4 side when the resin plate 2 is opaque, it is possible to efficiently increase the temperature of the joining interface. Furthermore, by irradiating the resin plate 2 with a laser from the metal plate 4 side, it is possible to use the resin plate 2 as a joining material regardless of its type. Furthermore, by heating the resin plate 2 from the metal plate 4 side, it is possible to provide a space on the resin plate 2 side, and pressure can be applied from the surface of the resin plate 2 as needed.

[0055] In the second step (S02), it is preferable to apply a pressure of 5 MPa or more to the interface to be joined. By applying a pressure of 5 MPa or more to the interface to be joined, the resin plate 2 and the metal plate 4 can be closely attached to each other, and a strong direct bonded interface 6 can be obtained. In addition, even if bubbles or the like are formed in the bonded portion due to the temperature increase, the bubbles can be discharged outside the system.

[0056] Furthermore, by adding the pressurizing step, the direct bonded interface 6 can be made uniform and quality variations can be reduced. By applying pressure, for example, the softened resin plate 2 spreads beyond the range of the heat-affected zone of the metal plate 4, and therefore the direct bonded interface 6 between the metal plate 4 and the resin plate 2 can be enlarged.

[0057] When pressurizing the interface to be joined, in the first step (S01), a heat-resistant glass plate or the like is placed against the surface of one or both of the materials to be joined to completely restrain the surface, thereby making it easier to press the interface to be joined.

[0058] The process parameters for laser irradiation, such as the laser output, scanning speed, and focal length, may be appropriately selected depending on the type and size of the materials to be joined, the area of ​​the interface to be joined, and the mechanical properties required of the resin-metal joined body 1.

[0059] (3) Third Step (S03: Hemming Step) The third step (S03) is a step for hemming the end of the metal plate 4. Although residual shear stress inevitably occurs at the direct bonded interface 6 formed in the second step (S02), by forming a hemmed portion at the end of the resin-metal bonded body 1, it is possible to suppress shear deformation at the direct bonded interface 6 extremely effectively.

[0060] The position, shape, and size of the hemmed portion 8 formed at the end of the metal plate 4 may be appropriately adjusted depending on the position, shape, and size of the direct bonded interface 6 between the resin plate 2 and the metal plate 4 at the overlapping surfaces, the shape, size, and desired mechanical properties of the resin-metal bonded body 1, etc., but it is preferable to optimize it with respect to the residual stress applied to the direct bonded interface 6.

[0061] The hemming method and processing conditions are not particularly limited as long as they do not impair the effects of the present invention, and conventionally known hemming methods and processing conditions can be used. For example, it is preferable to perform hemming using an appropriate roller hemming device.

[0062] (4) Hemmed Portion Joining Step The hemmed portion joining step is an optional step for joining or adhering the resin plate 2 and the metal plate 4 at the hemmed portion 8 .

[0063] At the hemmed portion 8, no stress that would cause separation of the contact surfaces between the resin plate 2 and the metal plate 4 is applied. Therefore, by joining or adhering the resin plate 2 and the metal plate 4 at the hemmed portion 8, the reliability of the resin-metal joined body 1 can be improved and separation of the resin plate 2 from the metal plate 4 can be effectively suppressed.

[0064] The method for joining or adhering the resin plate 2 and the metal plate 4 is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known joining or adhering methods can be used, but the joining methods described in Patent Documents 1 to 3 above can be suitably used.

[0065] Representative embodiments of the present invention have been described above, but the present invention is not limited to these, and various design modifications are possible, all of which are included in the technical scope of the present invention.

[0066] Example: The surface of a 1.0 mm x 100 mm x 1000 mm stainless steel (SUH409L) plate was irradiated with a laser in air to form a surface-modified region (first-step pretreatment). A YLP pulsed laser manufactured by IPG was used, and the laser irradiation conditions were an average power of 50 W (energy per pulse: 1 mJ), a focus diameter of 59 μm, and a scanning speed of 15,000 588.5 μm / s. The surface-modified region was modified over the entire surface of the stainless steel plate at a pitch of 90 μm (X direction: width direction of the plate) and 250 μm (Y direction: length direction of the plate). Additionally, in the width direction, a region extending 10 mm from the edge (region 8 in the plan view of Figure 1 ) was further modified at a pitch of 30 μm (X direction: width direction of the plate) and 70 μm (Y direction: length direction of the plate) in order to prevent partial delamination between the resin material and the metal material during the manufacturing process of a resin-metal bonded body.

[0067] Next, the surface of the stainless steel plate with the surface-modified region formed thereon was brought into contact with the surface of the fluororesin plate to form an overlapping surface (first step). The fluororesin plate was a 1.0 mm × 90 mm × 1000 mm polytetrafluoroethylene (PTFE) plate. The stainless steel plate and the fluororesin plate were overlapped with their width centers aligned, so that both ends of the fluororesin plate extended outward by 5.0 mm from the stainless steel plate.

[0068] Next, a laser was irradiated from the stainless steel plate side to heat the bonded interface having the surface-modified region, forming a direct bonded interface between the stainless steel plate and the fluororesin plate, resulting in a resin-metal bonded body (step 2). In step 2, a Laserline K8W semiconductor laser was used, and a zoom homogenizer was used in the optical system to create a 9 mm x 100 mm line laser. The laser was scanned 1000 mm at an output of 8000 W and a scanning speed of 9 mm / s. In step 2, a pressure of approximately 15 MPa was applied to the bonded interface.

[0069] Next, the stainless steel plate on the outer side of the edge of the fluororesin plate was bent 180° toward the fluororesin plate, and hemming was performed (third step). A photograph of the appearance of the obtained embodied resin-metal bonded body of the present invention is shown in Figure 5.

[0070] Comparative Example A comparative resin-metal bonded body was obtained in the same manner as in the example, except that the stainless steel plate on the outer side of the end of the fluororesin plate was not hemmed.

[0071] [Evaluation] Assuming that the resin-metal bonded body is installed inside the loading platform of a dump truck, the durability of the fluororesin plate that slides against the loading material was evaluated.

[0072] Assuming that the maximum load is applied to the surface of the fluororesin plate when starting to unload from a loaded state, the weight of the dead weight per unit area of ​​the inner surface height of 53 cm in the loading platform of a typical 10-ton dump truck (unit volume weight when loaded is 2.0 ton / m ３ In the case of the standard volume (70 mm thick), a load of material with a standard volume and a weight (iron piece) to compensate for the weight deficiency were placed in the load box so that a load of 2000 kg x 0.53 x test installation area was applied, and the material was slid, and the changes in the fluororesin plate were observed.

[0073] Here, assuming that dump trucks unload 2.5 times / day and operate 300 days / year, the number of loads due to abrasion of the cargo was set to 2.5 times / day x 300 days / year = 750 times / year. Since the reference value for a nominal wear life of 5 years is 750 times / year x 5 years = 3750 times (1875 reciprocations), the maximum number of reciprocations in the test was set to 2000 reciprocations.

[0074] A photograph of the equipment used in the test is shown in Figure 6. A roller compactor (Pavement Survey and Test Method Handbook B002-6) was used as the test equipment, and with the roller secured to a support with a chain and removed, a box (loading material box) for applying the loading material to the sample surface was secured in the center.

[0075] The materials used for the packing were concrete waste crushed with a crusher, with rebar and debris of 45 mm or larger removed. The packing materials were classified by particle size (37.5 mm or larger, 22.4-37.5 mm, 13.2-22.4 mm, 13.2 mm or smaller). Materials with mixed particle sizes were all uncompacted. First, the largest particle sizes (for example, 40 mm or larger) were lined up as evenly as possible at the bottom of the packing box, and the gaps between them were filled sequentially (if the largest was 40 mm or larger, fill with 40-25 mm, then further fill with 25-13 mm), and finally, the particles of 13 mm or smaller were filled to the specified height (30 mm below the top of the packing box).

[0076] The weight of the materials packed in the above process was calculated (measured as the weight lost from the prepared materials), and the shortfall was adjusted using a weight (piece of iron).

[0077] Next, the roller compactor's OFF counter was set to 2000 times and started. At this time, if it was determined that the balance of the loaded material had been lost after starting and the abrasion load had changed significantly, the loading state was appropriately corrected each time. After the test, the condition of the fluororesin plate was visually inspected to evaluate the durability of the resin-metal bonded body. If the fluororesin plate peeled off and the surface of the stainless steel plate was exposed, the test was terminated at that point. The test was conducted on three experimental resin-metal bonded bodies and three comparative resin-metal bonded bodies.

[0078] Figure 7 shows photographs of the appearance of the experimental resin-metal bonded bodies and the comparative resin-metal bonded bodies after the test. For all experimental resin-metal bonded bodies, no peeling of the fluororesin or significant damage was observed after 2000 reciprocating strokes. In contrast, for the comparative resin-metal bonded bodies, there was one specimen in which the fluororesin plate had significantly peeled off after 1353 reciprocating strokes. For the other test bodies, the fluororesin plate had not peeled off after 2000 reciprocating strokes, but many deep, streak-like grooves had formed, indicating greater damage than for the experimental resin-metal bonded bodies.

[0079] The change over time of the surface of the fluororesin plate with increasing number of sliding cycles for the exemplified resin-metal bonded bodies is shown in Fig. 8. Although the number of small scratches on the surface of the fluororesin plate increases somewhat with increasing number of sliding cycles, no significant damage was formed, and it is clear that the exemplified resin-metal bonded bodies have extremely good durability.

[0080] The above results confirm that the hemmed portion formed at the end of the resin-metal bonded body suppresses damage to the resin plate and peeling of the resin plate from the metal plate, which are caused by residual stress applied to the resin-metal direct bond interface formed on the overlapping surfaces of the resin plate and the metal plate, thereby extending the life of the resin-metal bonded body. Furthermore, because the hemmed portion is convex with respect to the surface of the resin plate, it is possible to suppress wear of the resin plate, which has a relatively low hardness, when soil or sand continuously contacts and slides against it.

[0081] REFERENCE SIGNS LIST 1: resin-metal bonded body, 2: resin plate, 4: metal plate, 6: direct bonded interface, 8: hemmed portion, 10: bonded or adhesive interface.

Claims

1. A resin-metal bonded body in which a resin plate and a metal plate are laminated, wherein the metal plate is larger in length and / or width than the resin plate, a direct bonding interface where the metal plate and the resin plate are directly bonded is formed on the overlapping surface of the resin plate and the metal plate, and the resin-metal bonded body has a hemming portion in which an end portion of the metal plate is bent.

2. The resin-metal bonded body according to claim 1, wherein the resin plate is a fluororesin.

3. The resin-metal bonded body according to claim 1 or 2, wherein the resin plate is polytetrafluoroethylene.

4. The resin-metal bonded body according to claim 1 or 2, wherein the metal plate is any one of an aluminum material, an aluminum alloy material, a titanium material, a titanium alloy material, and a steel material.

5. The resin-metal bonded body according to claim 1 or 2, wherein the thickness of the resin plate is 0.25 to 5 mm.

6. The resin-metal bonded body according to claim 1 or 2, wherein the resin plate and the metal plate of the hemming portion are joined or adhered.

7. A method for manufacturing the resin-metal bonded body according to claim 1 or 2, comprising: a first step of laminating a resin plate and a metal plate to form an overlapping surface; a second step of forming a direct bonding interface between the resin plate and the metal plate on the overlapping surface; and a third step of performing hemming on an end portion of the metal plate.

8. As a pretreatment of the first step, a pulsed laser is irradiated on the surface of the metal plate in an oxidizing atmosphere to form a surface modification region, in the first step, the surface modification region is brought into contact with the resin plate, and in the second step, the overlapping surface is heated by laser irradiation to form the direct bonding interface. The method for manufacturing a resin-metal bonded body according to claim 7.

9. The method for manufacturing a resin-metal bonded body according to claim 7, further comprising a fourth step of joining or adhering the resin plate and the metal plate of the hemming portion.

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