Metal resin assembly, bus bar, and method for manufacturing same

Abstract

The present invention addresses the problem of providing a metal resin assembly capable of improving electric characteristics caused by a skin effect and allowing a large current to flow even in the case of an AC current (AC). Provided is a metal resin assembly including n (where n is an integer equal to or greater than 1) constituent units (PM) in which a resin layer (P) and a metal layer (M) are laminated, or constituent units (PMP) in which a resin layer (P), a metal layer (M), and a resin layer (P) are laminated, wherein the metal resin assembly includes two or more metal layers (M). Also provided is a bus bar that includes the metal resin assembly. Also provided is a method for manufacturing the metal resin assembly.

Description

Metal-resin bonded body, bus bar, and method of manufacturing the same

[0001] The present invention relates to a metal-resin bonded body, a bus bar, and a method for manufacturing the same.

[0002] A bus bar is a conductor that efficiently supplies a large amount of current to each component with little loss, and is widely used as an alternative to cables and conductors (Patent Documents 1 to 3).

[0003] In recent years, with the spread of next-generation automobiles such as hybrid electric vehicles (HEVs) and electric vehicles (EVs), there has been an increasing demand for in-vehicle electronic devices and the like that can handle high voltages and large currents. Busbars have attracted attention as one of the components for such next-generation automobiles. Busbars function as so-called wiring components to electrically connect electronic components, electronic devices, or electronic equipment such as motors, inverters, or generators. For example, large currents flow through in-vehicle busbars, but depending on the electronic component, electronic device, electronic equipment, or electrical equipment, alternating current (AC) as well as direct current (DC) may also flow through the busbar.

[0004] JP 2015-170755 A JP 2017-142983 A JP 2020-43031 A

[0005] When a large current flows through a busbar, the cross-sectional area of ​​the metal material of the busbar needs to be increased to reduce the resistance of the metal material. However, when an alternating current (AC) flows through a busbar, even if the cross-sectional area of ​​the metal material of the busbar is increased, a phenomenon known as the "skin effect" occurs, in which the current flows only near the surface of the metal material, and energy loss occurs due to increased inductance, making it difficult to pass a large current through the busbar.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a metal-resin joined body that has improved electrical characteristics caused by the skin effect and that is capable of passing a large current, even an alternating current (AC).

[0007] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by employing a metal-resin bonded body having a configuration in which a plurality of resin layers and a plurality of metal layers are laminated in the thickness direction, and have thus completed the present invention. That is, the present invention provides the following [1] to

[25] . [1] A metal-resin bonded body including n (n = an integer of 1 or greater) structural units (PM) in which a resin layer (P) and a metal layer (M) are laminated, or n structural units (PMP) in which a resin layer (P), a metal layer (M), and a resin layer (P) are laminated, wherein the metal-resin bonded body includes two or more metal layers (M). [2] The metal-resin bonded body according to [1], in which the total thickness of the metal layers (M) accounts for 56% or more of the total thickness of the metal-resin bonded body. [3] The metal-resin bonded body according to [1] or [2], in which the resin layer (P) and the metal layer (M) are bonded directly or via an adhesion aid film in the structural unit (PM) or the structural unit (PMP). [4] The metal-resin joined body according to [3], wherein the thickness of the adhesion assistant film is 1 μm or less. [5] The metal-resin joined body according to [3] or [4], wherein the weight-average molecular weight of the components constituting the adhesion assistant film is 2,000 or less. [6] The metal-resin joined body according to any one of [3] to [5], wherein the adhesion assistant film contains, as a main component, a structural unit derived from a silane coupling agent. [7] The metal-resin joined body according to any one of [1] to [6], wherein the inductance value when a 100 kHz alternating current is passed therethrough is 90% or less of the inductance value when a 100 kHz alternating current is passed through the metal layer alone. [8] The metal-resin joined body according to any one of [1] to [7], wherein the metal layer (M) contains copper or a copper alloy. [9] The metal-resin joined body according to any one of [1] to [8], wherein the metal layer (M) contains aluminum or an aluminum alloy.

[10] The metal resin joined body according to any one of [1] to [9], wherein the resin layer (P) contains a polyphenylene sulfide resin as a main component.

[11] The metal resin joined body according to any one of [1] to

[10] , wherein the resin layer (P) contains a polyamide resin as a main component.

[12] The metal resin joined body according to any one of [1] to

[11] , wherein the resin layer (P) contains a polypropylene resin as a main component.

[13] The metal resin joined body according to any one of [1] to

[12] , wherein each resin layer (P) has a thickness of 1 to 100 μm.

[14] The metal-resin bonded body according to any one of [1] to

[13] , wherein each metal layer (M) has a thickness of 0.05 to 2.0 mm.

[15] The metal-resin bonded body according to any one of [1] to

[14] , wherein the total thickness of the metal-resin bonded body is 0.5 mm or more.

[16] The metal-resin bonded body according to any one of [1] to

[15] , wherein the metal-resin bonded body is used for a bus bar.

[17] A bus bar comprising the metal-resin bonded body according to any one of [1] to

[16] .

[18] A method for producing the metal-resin bonded body according to any one of [1] to

[16] , comprising obtaining the structural unit (PM) or the structural unit (PMP) by thermocompression bonding the metal layer (M) and the resin layer (P) directly or via an adhesion aid film.

[19] A method for producing a metal resin joined body according to

[18] , comprising: (1) surface-treating the surface of at least one selected from the metal layer (M) and the resin layer (P) with a silane coupling agent treatment liquid to form an adhesion aid film; and (2) laminating an untreated resin layer (P) on the surface of the surface-treated metal layer (M), or laminating an untreated metal layer (M) on the surface-treated resin layer (P), followed by thermocompression bonding.

[20] A method for producing a metal resin joined body according to

[18] or

[19] , further comprising laminating a structural unit (PM) or a structural unit (PMP).

[21] A laminate for producing a busbar, in which one resin layer (P) and one metal layer (M) are bonded together directly or via an adhesion aid film.

[22] The laminate for producing a busbar according to

[21] , in which another metal layer (M) is bonded onto the resin layer (P), directly or via an adhesion aid film.

[23] The laminate for producing busbars according to

[21] or

[22] , wherein the resin layer (P) and the metal layer (M) are bonded via an adhesion aid film, and the adhesion aid film has a thickness of 1 μm or less.

[24] The laminate for producing busbars according to any one of

[21] to

[23] , wherein the components constituting the adhesion aid film have a weight average molecular weight of 2000 or less.

[25] The laminate for producing busbars according to any one of

[21] to

[24] , wherein the adhesion aid film contains, as a main component, a structural unit derived from a silane coupling agent.

[0008] [A] A metal-resin bonded body for use in a busbar, the metal-resin bonded body including n (n is an integer of 1 or greater) structural units in which a resin layer (P) and a metal layer (M) are laminated, and two or more metal layers (M). [B] Use of a metal-resin bonded body for manufacturing a busbar, the metal-resin bonded body including n (n is an integer of 1 or greater) structural units in which a resin layer (P) and a metal layer (M) are laminated, and two or more metal layers (M). [C] A method for manufacturing a busbar using a metal-resin bonded body including n (n is an integer of 1 or greater) structural units in which a resin layer (P) and a metal layer (M) are laminated, and two or more metal layers (M).

[0009] According to the present invention, it is possible to obtain a metal-resin bonded body capable of passing a large current by suppressing the influence of the skin effect and suppressing energy loss due to an increase in inductance, thereby obtaining a bus bar capable of passing a large current even when using AC.

[0010] Fig. 1 is a diagram showing an example of the configuration of a metal-resin bonded body. Fig. 2 is a diagram showing an example of the configuration of a metal-resin bonded body. Fig. 3 is a diagram showing an example of the configuration of a metal-resin bonded body. Fig. 4 is a diagram showing an example of the configuration of a metal-resin bonded body. Fig. 5 is a diagram showing an example of the configuration of a metal-resin bonded body. Fig. 6 is a diagram showing an example of the configuration of a metal-resin bonded body. Fig. 7 is a diagram showing an example of the configuration of a metal-resin bonded body.

[0011] Next, an example of an embodiment of the present invention will be described. However, the present invention is not limited to the embodiment described below, and can be implemented with any modifications within the scope of the gist of the present invention. In this specification, when "X to Y" (X and Y are arbitrary numbers) is used, unless otherwise specified, it means "X or more and Y or less," and also includes "preferably greater than X" or "preferably smaller than Y." Furthermore, when "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), it also includes the meaning "preferably greater than X" or "preferably less than Y." In the following description, the terms "film" and "sheet" are not clearly distinguished from each other, and the term "film" includes the term "sheet," and the term "sheet" includes the term "film."

[0012] <Metal-resin bonded body> This embodiment relates to a metal-resin bonded body including n (where n = an integer of 1 or more) structural units (PM) in which a resin layer (P) and a metal layer (M) are laminated, or structural units (PMP) in which a resin layer (P), a metal layer (M), and a resin layer (P) are laminated. In this specification, the structural unit is a unit including one metal layer (M) and at least one resin layer (P). That is, examples of the structural unit include the structural unit (PM) in which a resin layer (P) and a metal layer (M) are laminated, or the structural unit (PMP) in which a resin layer (P), a metal layer (M), and a resin layer (P) are laminated. As described above, the present embodiment relates to a metal-resin joined body that includes n (n is an integer of 1 or greater) structural units (PM) in which a resin layer (P) and a metal layer (M) are laminated together, or n structural units (PMP) in which a resin layer (P), a metal layer (M) and a resin layer (P) are laminated together, and that includes two or more metal layers (M).

[0013] Because the metal-resin bonded body of this embodiment has the above-mentioned configuration, it has a configuration in which the resin layers (P) and the metal layers (M) are alternately laminated. That is, in a metal-resin bonded body formed by alternately laminating the resin layers (P) and the metal layers (M), adjacent resin layers (P) and metal layers (M) are the constituent units (PM) referred to in this specification, and a layer configuration in which the resin layer (P), the metal layer (M), and the resin layer (P) are laminated in this order is the constituent unit (PMP) referred to in this specification. Naturally, the metal-resin bonded body of the present invention includes not only metal-resin bonded bodies formed by laminating constituent units, but also metal-resin bonded bodies formed by simply alternately laminating the resin layers (P) and the metal layers (M).

[0014] 1 , the structural unit constituting the metal-resin bonded body includes n structural units (PM) (where n is an integer of 1 or greater) each of which is formed by laminating one resin layer (P) and one metal layer (M). A metal-resin bonded body is obtained by laminating n such structural units (PM) and, if necessary, further laminating a metal layer (M) so that the outermost layer is the metal layer (M).

[0015] The metal-resin bonded body may also have a structural unit (PMP). As shown in Fig. 2, the structural unit constituting the metal-resin bonded body may include n structural units (PMP) (where n is an integer of 1 or greater) each formed by laminating a resin layer (P), a metal layer (M), and a resin layer (P) in this order. In this case, when one structural unit (PMP) and another structural unit (PMP) are laminated, the resin layers (P) are laminated so that they are in contact with each other.

[0016] The metal-resin bonded body may contain both the structural unit (PM) and the structural unit (PMP). Furthermore, as shown in Figures 1 and 2, the dimensions of the multiple metal layers (M) included in the metal-resin bonded body are preferably the same, and the dimensions of the multiple resin layers (P) are also preferably the same. Furthermore, the dimensions of the metal layers (M) and the resin layers (P) are preferably the same.

[0017] In this embodiment, a metal-resin bonded body capable of passing a large current can be obtained by laminating a plurality of resin layers (P) and metal layers (M) in the thickness direction, thereby suppressing the influence of the skin effect and suppressing energy loss due to increased inductance. Furthermore, since the metal-resin bonded body of this embodiment includes a resin layer, it can be made lightweight and has good bending processability. Therefore, the metal-resin bonded body of this embodiment is suitable as a busbar used in various batteries and power modules used in hybrid electric vehicles (HEVs) or electric vehicles (EVs). In this specification, the term "power module" refers to a module used for power conversion, such as converting frequency, voltage, or DC current to AC current or converting AC current to DC current.

[0018] The electrical properties of the metal-resin bonded body can be evaluated by measuring the current value, inductance value, etc. using a known method. Specifically, in this embodiment, the metal-resin bonded body is used as a sample and connected to an LCZ meter or an LCR meter to measure the inductance value. A smaller inductance value indicates a smaller resistance and a larger current flow.

[0019] Furthermore, the inductance value when a 100 kHz AC current is passed through the metal-resin bonded body of this embodiment is preferably 90% or less, more preferably 85% or less, even more preferably 80% or less, even more preferably 70% or less, even more preferably 60% or less, and particularly preferably 50% or less, of the inductance value when a 100 kHz AC current is passed through the metal layer alone contained in the metal-resin bonded body. The thickness of the metal layer alone is approximately the same as the total thickness of the metal layers contained in the metal-resin bonded body. The skin effect becomes more pronounced as the frequency increases. For example, as in the measurements in the examples, measurements are performed using an LCR meter in the frequency range from 1 kHz to 1 MHz, and the values ​​at a frequency of 100 kHz are compared.

[0020] The smaller the inductance value, the smaller the resistance and the greater the current flow. It is believed that the greater the number of metal layers and resin layers stacked in a metal-resin bonded body, the greater the effect of increasing the current flow in the metal-resin bonded body. If the metal-resin bonded body and a single metal layer are made to have the same volume, the metal-resin bonded body can pass a larger current, so it is thought that the volume can be reduced by the amount of the larger current, which also makes it possible to make parts more compact.

[0021] The current density of the metal-resin bonded body in this embodiment is 0.5 A / mm ２ It is preferable that the current is 1.0 A / mm or more. ２ More preferably, it is 1.2 A / mm ２ The current density of the metal-resin bonded body is more preferably 4.0 A / mm ２ It is preferable that:

[0022] In this embodiment, in the structural unit (PM) or structural unit (PMP), the resin layer (P) and the metal layer (M) are preferably bonded directly or via an adhesion aid film. When the resin layer (P) and the metal layer (M) are bonded directly, no other layer is present between the resin layer (P) and the metal layer (M). In addition, in this specification, the adhesion aid film refers to a coating provided between the resin layer (P) and the metal layer (M), and such a coating is distinguished from an adhesive layer provided to bond the resin layer and the metal layer. Specifically, the thickness of the adhesion aid film is preferably 1 μm or less, more preferably 0.8 μm or less, even more preferably 0.6 μm or less, even more preferably 0.5 μm or less, even more preferably 0.3 μm or less, and particularly preferably 0.1 μm or less.

[0023] In this embodiment, the adhesion aid film does not substantially contain adhesive polymers contained in so-called adhesive layers. More specifically, the weight-average molecular weight of the components constituting the adhesion aid film is preferably 2000 or less, more preferably 1800 or less, even more preferably 1600 or less, and particularly preferably 1400 or less. Thus, the adhesion aid film of this embodiment is preferably a coating containing a low-molecular-weight compound as its main component, rather than a polymer.

[0024] The adhesion aid film preferably contains, as a main component, a structural unit derived from a silane coupling agent. The silane coupling agent is an organosilicon compound having an organic functional group and a hydrolyzable group such as an alkoxy group in one molecule. Examples of silane coupling agents include epoxy group-containing compounds such as 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; vinyl group-containing compounds such as vinyltrimethoxysilane and vinyltriethoxysilane; styryl group-containing compounds such as p-styryltrimethoxysilane and p-styryltriethoxysilane; (meth)acrylic group-containing compounds such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-( ... amino group-containing compounds such as N-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltriethoxysilane; isocyanurate group-containing compounds such as tris(trimethoxysilylpropyl)isocyanurate and tris(triethoxysilylpropyl)isocyanurate; and mercapto group-containing compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropylmethyldiethoxysilane.Among the above compounds, from the viewpoint of achieving both adhesion to the metal layer (M) and adhesion to the resin layer (P), epoxy group-containing silane coupling agents, silane coupling agents containing a double bond such as a vinyl group or a (meth)acrylic group, and amino group-containing silane coupling agents are more preferred. The silane coupling agents may be used alone or in combination of two or more.

[0025] [Resin Layer (P)] The metal-resin bonded body of this embodiment has a resin layer (P). A conventionally known resin can be used as the resin constituting the resin layer (P). Note that, in this embodiment, the resin layer (P) is a layer different from a so-called adhesive layer. For example, the melting point of the resin constituting the resin layer (P) is preferably 130°C or higher.

[0026] Specific examples of the resin constituting the resin layer (P) include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polymethylpentene, polyphenylene ether, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polymethyl methacrylate, polycarbonate, ABS, polyarylate, polyetherimide, polyamideimide, polysulfone, polyether sulfide, polyphenylene sulfide, polyaryletherketone, liquid crystal polymer, copolymers thereof, and mixtures thereof. Among these, particularly from the viewpoint of improving adhesion to the metal layer and / or the heat resistance of the resin layer, at least one selected from the group consisting of polycarbonate, aliphatic polyamide, aromatic polyamide, polypropylene, polyphenylene ether, polyether sulfide, polyphenylene sulfide, polyetherimide, and polysulfone is preferred, at least one selected from the group consisting of aliphatic polyamide, aromatic polyamide, polyphenylene sulfide, and polypropylene is more preferred, and at least one selected from the group consisting of aliphatic polyamide, modified polyphenylene sulfide, and polypropylene is even more preferred.

[0027] The resin layer (P) preferably contains a polyphenylene sulfide-based resin as a main component, a polyamide-based resin as a main component, or a polypropylene-based resin as a main component. In this specification, the term "main component" refers to a resin that accounts for 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more of the total mass of the resin layer. The polyphenylene sulfide-based resin includes unmodified polyphenylene sulfide as well as modified polyphenylene sulfide. The polyamide-based resin includes aromatic polyamide and aliphatic polyamide, and the polyamide may be modified polyamide. The polypropylene-based resin includes unmodified polypropylene as well as modified polypropylene.

[0028] Among these, it is preferable that the resin layer (P) contains a polyphenylene sulfide resin as a main component, and the melt viscosity of the polyphenylene sulfide resin is preferably 250 Pa·s or more and 2000 Pa·s or less.

[0029] Polyphenylene sulfide resins have a repeating unit represented by the following formula (1). The repeating unit is a benzene ring with a sulfur atom attached. n is an integer of 2 or greater, preferably 80 to 1,000, more preferably 100 to 700, and even more preferably 150 to 500.

[0030] Polyphenylene sulfide resins having a substantially linear structure are preferred from the viewpoint of film formability, physical properties, etc. However, within the range that does not substantially deteriorate these physical properties, for example, a polymerized cross-linked product obtained by using an effective amount of a cross-linking agent (e.g., trihalobenzene) during polymerization, or a thermally cross-linked product obtained by cross-linking a polymer by heat treatment in the presence of oxygen, etc., can also be used.

[0031] The polyphenylene sulfide resin is also preferably a modified polyphenylene sulfide. Examples of the modified polyphenylene sulfide include modified polyphenylene sulfides obtained by graft-reacting unmodified polyphenylene sulfide with a modifier having both a double bond and a reactive functional group, such as glycidyl methacrylate, glycidyl acrylate, acrylic acid, maleic anhydride, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, acrylamide, N-[4-(2,3-epoxypropoxy)-3,5-dimethylphenylmethyl]acrylamide, or vinyltrimethoxysilane, to introduce functional groups such as epoxy groups, carboxyl groups, acid anhydride groups, alcoholic hydroxyl groups, amino groups, and alkoxysilyl groups.

[0032] The modified polyphenylene sulfide may be one obtained by melt-reacting a modifying agent having both a disulfide group and a reactive functional group, such as 4,4'-dithiodi(n-butylic acid), dithiodiacetic acid, dithiodianiline, or dithiodibenzoic acid, to introduce a functional group such as a carboxyl group or an amino group. The modified polyphenylene sulfide may also be one obtained by melt-reacting a modifying agent having both a mercapto group and a reactive functional group, such as thiomalic acid, mercaptoacetic acid, mercaptopropionic acid, or aminothiophenolmercaptobenzoic acid, to introduce a functional group such as a carboxyl group or an amino group. Alternatively, the modified polyphenylene sulfide may be one obtained by reacting a silane coupling agent, such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, or γ-aminopropyltriethoxysilane.

[0033] The polyphenylene sulfide-based resin constituting the resin layer (P) is also preferably a copolymerized polyphenylene sulfide. Examples of copolymerized polyphenylene sulfide include copolymerized polyphenylene sulfide produced by copolymerizing functional group-containing monomers, such as copolymerized polyphenylene sulfide containing amino groups, hydroxyl groups, carboxyl groups, etc. Furthermore, modified copolymerized polyphenylene sulfide can also be used, which has been introduced with functional groups such as carboxyl groups, acid anhydride groups, hydroxyl groups, and amino groups by melt-reacting a modifier that simultaneously contains a sulfonic acid group or a nitro group and a reactive functional group, such as 4-hydroxy-1-naphthalenesulfonic acid, 3-amino-4-hydroxybenzenesulfonic acid, 4-aminobenzenesulfonic acid, 3-sulfobenzoic acid, 4-sulfophthalic acid, 4-nitronaphthalene-1,8-dicarboxylic anhydride, 4-nitrophthalic anhydride, or nitrobenzoic acid. For example, by changing the chemical structure of a polyphenylene sulfide precursor and copolymerizing it with a normal polyphenylene sulfide precursor, good physical properties such as adhesion to a metal layer can be obtained, which is more preferable.

[0034] The resin layer (P) may be a blend of a polyphenylene sulfide-based resin and other resin components. In this case, the type of other resin components is not particularly limited, and examples thereof include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polymethylpentene, polyphenylene ether, polyethylene terephthalate, polybutylene terephthalate, polyacetal, aliphatic polyamide, polymethyl methacrylate, polycarbonate, ABS, aromatic polyamide, polyarylate, polyetherimide, polyamideimide, polysulfone, polyether sulfide, polyaryletherketone, liquid crystal polymer, copolymers thereof, and mixtures thereof. Among these, from the viewpoint of improving adhesion to a metal layer and to a resin layer (e.g., polyphenylene sulfide) provided on the outermost layer, at least one selected from the group consisting of polycarbonate, polypropylene, polyphenylene ether, polyether sulfide, polyetherimide, and polysulfone is preferred, and polyphenylene ether is more preferred.

[0035] The resin layer (P) may contain a polyamide-based resin as a main component. Examples of polyamide-based resins include aliphatic polyamides and aromatic polyamides, with aliphatic polyamides being preferred. Examples of aliphatic polyamides include ring-opening polymers of cyclic lactams and polycondensates of aminocarboxylic acids, such as polyamide 4, polyamide 5, polyamide 6, polyamide 7, polyamide 8, polyamide 9, polyamide 10, polyamide 11, and polyamide 12. Polycondensates of dicarboxylic acids and diamines are also suitable, such as polyamide 46, polyamide 410, polyamide 412, polyamide 66, polyamide 610, polyamide 612, polyamide 96, polyamide 910, polyamide 912, polyamide 106, polyamide 1010, and polyamide 1012. These may be copolymerized using any copolymerization method, such as random copolymerization, block copolymerization, or graft copolymerization.

[0036] Among aliphatic polyamides, polyamide 6 (6 nylon), polyamide 66 (66 nylon), and polyamide 6,66 are preferred because they have an excellent balance of heat resistance, film-forming properties, and mechanical strength, and polyamide 6 (6 nylon) is particularly preferred because of its versatility and high economical value. Polyamide 6 (6 nylon) preferably has a relative viscosity (96% sulfuric acid) of 1.0 to 5.0, more preferably 2.0 to 4.5, and particularly preferably 2.5 to 4.0. When the relative viscosity of polyamide 6 (6 nylon) is within the above range, a resin layer (P) having excellent processability and mechanical strength can be obtained.

[0037] The resin layer (P) may contain a polypropylene-based resin as a main component. The polypropylene-based resin may be modified polypropylene. Examples of modified polypropylene include silane-modified polypropylene, acid-modified polypropylene, copolymers of propylene and other polar monomers, and polypropylene modified with a halogen element. Examples of modified polypropylene with a halogen element include polypropylene into which a halogen element such as fluorine, chlorine, or bromine has been introduced. The PP-based resin may also be a copolymer such as a block copolymer or a random copolymer.

[0038] From the viewpoint of heat resistance, the melting point of the resin used in the resin layer (P) is preferably 100°C or higher, more preferably 150°C or higher, and even more preferably 200°C or higher.

[0039] (Thickness of Resin Layer (P)) The thickness of one resin layer (P) is preferably 1 μm or more, more preferably 5 μm or more, and particularly preferably 10 μm or more. On the other hand, the upper limit of the thickness of the resin layer (P) is preferably 100 μm or less, taking into account handleability. In this embodiment, the metal-resin bonded body preferably includes a plurality of resin layers (P), and the thicknesses of the plurality of resin layers (P) are preferably the same, but may be different. By setting the thickness of the resin layer (P) within the above range, the adhesion between the resin layer (P) and the metal layer (M) can be improved, and further, the metal-resin bonded body can be more easily thinned and lightweight.

[0040] (Proportion of Resin Layer (P) in Metal-Resin Bonded Body) The proportion of the thickness of the resin layer (P) (total thickness of the resin layers) in the metal-resin bonded body is preferably 45% or less, more preferably 40% or less. On the other hand, the lower limit of the proportion of the thickness of the resin layer (P) (total thickness of the resin layers) is 5% or more, preferably 10% or more, from the viewpoint of ease of handling. By setting the proportion of the thickness of the resin layer (P) (total thickness of the resin layers) within the above range, it becomes possible to effectively suppress heat generation due to current flow while achieving the effect of reducing the thickness and weight of the metal-resin bonded body.

[0041] Each resin layer (P) is preferably a single layer, but may be multilayered. When the resin layer (P) is multilayered, the same type of resin may be used for each resin layer (P), or different resins or various additives may be blended into each resin layer (P). When a multilayer resin layer (P) is constructed, an adhesive layer or the like may be provided between the layers. Even when the resin layer (P) is multilayered, the thickness of each resin layer (P) is preferably 1 μm or more, more preferably 5 μm or more, and particularly preferably 10 μm or more. The thickness of each resin layer (P) is preferably 100 μm or less.

[0042] (Other Additives) The resin layer (P) may contain other additives as long as the gist of the present invention is not impaired. Examples of other additives include various additives such as heat stabilizers, antioxidants, UV absorbers, light stabilizers, antibacterial and antifungal agents, antistatic agents, lubricants, pigments, dyes, and fillers. The content of other additives is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total mass of the resin layer (P).

[0043] (Method for manufacturing resin layer (P)) A general molding method can be used for manufacturing the resin layer (P). For example, the resin layer (P) can be molded into a desired shape such as a film or a sheet by extrusion molding, injection molding, casting molding such as melt casting, press molding, etc. In each molding method, the apparatus and processing conditions are not particularly limited, and known methods can be used. Furthermore, in order to improve adhesion, the surface of the resin layer may be subjected to various surface treatments such as corona treatment or painting, or treatments such as metal vapor deposition.

[0044] [Metal Layer (M)] The metal-resin bonded body of this embodiment has a metal layer (M). From the viewpoint of electrical properties, it is preferable to use copper or a copper alloy, or aluminum or an aluminum alloy, as the metal constituting the metal layer. Specific examples of copper or copper alloys include high-purity copper such as tough-pitch copper, oxygen-free copper, and phosphorus-deoxidized copper, as well as copper alloys such as brass, phosphor bronze, Cu—Fe alloys, Cu—Fe—P alloys, and Cu—Ni—Si alloys, but are not particularly limited thereto. Among these, from the viewpoint of further improving electrical properties, it is preferable that the copper or copper alloy has a copper purity of 99.90% or more.

[0045] Specific examples of aluminum alloys include non-heat-treatable or heat-treatable aluminum alloys specified in or conforming to JIS. Non-heat-treatable aluminum alloys include pure aluminum (1000 series), Al-Mn alloys (3000 series), Al-Si alloys (4000 series), and Al-Mg alloys (5000 series). Heat-treatable aluminum alloys include Al-Cu-Mg alloys (2000 series), Al-Mg-Si alloys (6000 series), and Al-Zn-Mg alloys (7000 series).

[0046] Furthermore, in the metal-resin bonded body, the types of metal layers to be combined are not limited, and a plurality of different metal layers (two or more types) may be combined, such as a combination of a copper layer and an aluminum layer, and can be appropriately selected depending on the purpose.

[0047] The metal layer (M) is preferably formed from a metal plate made of the above-mentioned metal. The metal content in the metal layer (M) is 80 mass % or more, preferably 90 mass % or more, more preferably 95 mass % or more, and even more preferably 99 mass % or more, based on the total mass of the metal layer.

[0048] The surface of the metal layer (M) may be plated with one or more metals to enhance adhesion to the resin layer (P) or to prevent surface oxidation. The surface of the metal layer (M) may also be provided with an inorganic oxide coating, such as a chemical conversion coating formed by treatments such as chromate treatment, phosphate treatment, chromate / phosphate treatment, electrolytic chromate treatment, chromate treatment, and anodizing. Other treatments may also be used, such as chemical treatments such as etching, painting, resin coating, and embossing, as well as physical treatments.

[0049] (Thickness of Metal Layer (M)) The thickness of the metal layer (M) is preferably 0.05 mm or more, more preferably 0.10 mm or more. The thickness of the metal layer (M) is preferably 2.0 mm or less, more preferably 1.5 mm or less. The thicknesses of the multiple metal layers (M) constituting the metal-resin bonded body are preferably the same, but may be different. By setting the thickness of the metal layer (M) within the above range, good bending workability is achieved. Furthermore, by setting the thickness of the metal layer (M) within the above range, the metal-resin bonded body can be more easily made thinner and lighter, and the skin effect can be effectively suppressed.

[0050] (Proportion of Metal Layer (M) in Metal-Resin Bonded Body) The ratio of the thickness of the metal layer (M) (total thickness of the metal layers) to the overall thickness of the metal-resin bonded body is preferably 56% or more, more preferably 60% or more, even more preferably 65% ​​or more, and particularly preferably 70% or more. On the other hand, the upper limit of the ratio of the thickness of the metal layer (M) (total thickness of the metal layers) is preferably 95% or less, more preferably 90% or less, and even more preferably 85% or less. By setting the ratio of the thickness of the metal layer (M) (total thickness of the metal layers) within the above range, a bus bar capable of passing a large current while suppressing the influence of the skin effect can be obtained. The ratio of the thickness of the metal layer (M) (total thickness of the metal layers) can be calculated using the following formula: Thickness of the metal layer (M) = Total thickness of the metal layers / Thickness of the metal-resin bonded body × 100

[0051] [Method for Producing Metal-Resin Bonded Body] The metal-resin bonded body can be produced, for example, by the following production method.

[0052] The method for producing a metal-resin bonded body preferably includes a step of obtaining a structural unit by thermocompression bonding the metal layer (M) and the resin layer (P) directly or via an adhesion aid film. Specifically, the method for producing a metal-resin bonded body preferably includes a step of obtaining a structural unit (PM) or a structural unit (PMP) by thermocompression bonding the metal layer (M) and the resin layer (P) directly or via an adhesion aid film (hereinafter, the step of obtaining the structural unit (PM) or the structural unit (PMP) may also be simply referred to as a "step of obtaining a structural unit"). In the step of obtaining a structural unit, the thermocompression bonding temperature is set to be equal to or higher than the melting point of the resin layer (P), so that the resin melts and can be bonded to the metal layer.

[0053] In the step of obtaining the structural unit, the metal layer (M) and the resin layer (P) are thermocompression bonded directly or via an adhesion aid film. In the thermocompression bonding step, it is preferable to perform heat press bonding or roll-to-roll thermocompression bonding. In this specification, heat press bonding is a method of, for example, fusing the resin layer (P) and the metal layer (M) cut into sheets by applying pressure from above and below using a heat press, and roll-to-roll thermocompression bonding is a method of fusing the resin layer (P) and the metal layer (M) wound in a coil or roll shape by continuously passing them through a pair of rolls while unwinding them, thereby applying thermocompression bonding. The structural unit (PM) or the structural unit (PMP) is obtained by thermocompression bonding the metal layer (M) and the resin layer (P) by heat press bonding or roll-to-roll thermocompression bonding.

[0054] The thermocompression bonding temperature in the step of obtaining the structural units is preferably the melting point of the resin constituting the resin layer (P) + 5°C or higher, more preferably the melting point of the resin + 10°C or higher, and even more preferably the melting point of the resin + 20°C or higher. This allows the resin layer (P) to be sufficiently melted, thereby increasing the adhesive strength with the metal layer (M). In the case of heat press bonding, the thermocompression bonding time in the step of obtaining the structural units is preferably 1 minute or more, more preferably 2 minutes or more, and even more preferably 3 minutes or more. From the viewpoint of productivity, the thermocompression bonding time is preferably 20 minutes or less, more preferably 15 minutes or less, and even more preferably 10 minutes or less. On the other hand, in the case of roll-to-roll thermocompression bonding, thermocompression bonding can be achieved in a shorter time than in the case of heat press bonding, depending on the line speed. Therefore, from the viewpoint of productivity, the thermocompression bonding time is preferably in the range of 1 second to 1 minute, preferably 1 second to 30 seconds.

[0055] In this embodiment, in the step of obtaining the structural units, it is preferable to perform thermocompression bonding by passing a set of structural units between a pair of rolls (compression rolls). The temperatures of the pair of rolls may be the same or different. The width between the pair of rolls can be adjusted appropriately depending on the thickness of the structural units. In this embodiment, the thermocompression bonding step using rolls and the hot press bonding step may be performed in combination.

[0056] In the step of obtaining the structural unit, the metal layer (M) and the resin layer (P) are preferably thermocompression bonded so as to be in direct contact with each other. In such a case, there is no need to provide an adhesive layer or the like between the metal layer (M) and the resin layer (P), which enables the metal-resin bonded body to be made thinner and lighter. In addition, the proportion of the thickness of the metal layer (M) in the metal-resin bonded body (the total thickness of the metal layers) can be increased. On the other hand, when the metal layer (M) and the resin layer (P) are laminated via an adhesion aid film, examples of the adhesion aid film include a coating mainly composed of a low-molecular-weight compound having a weight-average molecular weight of 2000 or less.

[0057] The method for producing a metal-resin bonded body may include, prior to the step of obtaining the structural unit, (1) a step of surface-treating the surface of at least one selected from the metal layer (M) and the resin layer (P) with a silane coupling agent treatment liquid, and (2) a step of laminating an untreated resin layer (P) on the surface of the surface-treated metal layer (M) or laminating an untreated metal layer (M) on the surface-treated resin layer (P) and thermocompression bonding. In step (1), it is preferable to surface-treat the surface of at least one selected from the metal layer (M) and the resin layer (P) with a silane coupling agent treatment liquid, and in particular, it is preferable to surface-treat the surface of the metal layer (M) with a silane coupling agent treatment liquid. By performing such a step, an adhesion aid film containing a structural unit derived from a silane coupling agent as a main component is formed. Note that when obtaining the structural unit (PMP), both surfaces of the metal layer (M) may be surface-treated with a silane coupling agent treatment liquid.

[0058] The silane coupling agent treatment liquid used in step (1) contains a silane coupling agent, which is an organosilicon compound having an organic functional group and a hydrolyzable group such as an alkoxy group in one molecule. Examples of silane coupling agents include epoxy group-containing compounds such as 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; vinyl group-containing compounds such as vinyltrimethoxysilane and vinyltriethoxysilane; styryl group-containing compounds such as p-styryltrimethoxysilane and p-styryltriethoxysilane; (meth)acrylic group-containing compounds such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-( ... amino group-containing compounds such as N-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltriethoxysilane; isocyanurate group-containing compounds such as tris(trimethoxysilylpropyl)isocyanurate and tris(triethoxysilylpropyl)isocyanurate; and mercapto group-containing compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropylmethyldiethoxysilane.Among the above compounds, from the viewpoint of achieving both adhesion to the metal layer (M) and adhesion to the resin layer (P), epoxy group-containing silane coupling agents, silane coupling agents containing a double bond such as a vinyl group or a (meth)acrylic group, and amino group-containing silane coupling agents are more preferred. The silane coupling agents may be used alone or in combination of two or more.

[0059] The silane coupling agent is preferably applied to the surface of the metal layer (M) or the resin layer (P) as a liquid coating solution (silane coupling agent treatment solution), and a drying step is preferably performed as necessary. The silane coupling agent treatment solution preferably contains a solvent, and the silane coupling agent may be dissolved in the solvent or may be dispersed in the solvent.

[0060] The content of the silane coupling agent contained in the silane coupling agent treatment liquid is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, based on the total mass of the silane coupling agent treatment liquid.Furthermore, the content of the silane coupling agent is preferably 1% by mass or less, more preferably 0.8% by mass or less, and even more preferably 0.5% by mass or less, based on the total mass of the silane coupling agent treatment liquid.

[0061] The solvent contained in the silane coupling agent treatment liquid is not particularly limited, but either water or an organic solvent may be used. Among them, from the viewpoint of environmental protection, it is preferable to use an aqueous coating liquid using water as the solvent. The aqueous coating liquid may contain a small amount of organic solvent. The specific amount of organic solvent is preferably less than that of water on a mass basis, for example, preferably less than 30 mass%, more preferably less than 20 mass%, and even more preferably less than 10 mass% of the total mass of the solvent.

[0062] Examples of organic solvents that can be used in combination with water include alcohols such as ethanol, isopropanol, ethylene glycol, and glycerin; ethers such as ethyl cellosolve, t-butyl cellosolve, propylene glycol monomethyl ether, and tetrahydrofuran; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; and amines such as dimethylethanolamine. These can be used alone or in combination. By appropriately selecting and adding these organic solvents to the aqueous coating liquid as needed, the stability and coatability of the coating liquid can sometimes be improved.

[0063] The method for applying the silane coupling agent treatment liquid to the surface of the metal layer (M) or the resin layer (P) may be, for example, a conventionally known application method such as air doctor coating, blade coating, rod coating, bar coating, knife coating, squeeze coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, kiss roll coating, cast coating, spray coating, curtain coating, calendar coating, or extrusion coating.

[0064] Furthermore, in order to improve the coatability or adhesiveness of the silane coupling agent treatment liquid, the surface of the metal layer (M) or the resin layer (P) may be subjected to a surface treatment such as chemical treatment, corona discharge treatment, plasma treatment, ozone treatment, chemical treatment, or solvent treatment before application of the silane coupling agent treatment liquid.

[0065] In this embodiment, the amount of the silane coupling agent treatment liquid to be applied is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 15 μm or more in terms of the thickness of the wet coating, and is preferably 30 μm or less, more preferably 20 μm or less in terms of the thickness of the wet coating.

[0066] The thickness of the surface treatment layer formed by applying the silane coupling agent treatment liquid (thickness after application and drying) is preferably 0.1 μm or less, and more preferably 0.05 μm or less. Thus, the thickness of the surface treatment layer formed by applying the silane coupling agent treatment liquid is thin, which differs from conventional structures using adhesive layers. If an adhesive layer is used in a metal-resin bonded body, a space equivalent to the thickness of the adhesive layer is required depending on the number of laminations. For example, if the number of laminations of the structural unit is 5 and the thickness of the adhesive layer after drying is 20 μm, a total of 100 μm of extra thickness space is required. On the other hand, since the present invention does not require an adhesive layer, the thickness space calculated above is not necessary. Instead, the thickness can be reduced or the space can be used to laminate a new metal layer. This makes it possible to manufacture bus bars that are thinner than conventional products and can carry a larger current, thereby enabling higher performance.

[0067] After the application of the silane coupling agent treatment liquid, a drying step is preferably performed. The drying step is preferably a step of removing the solvent contained in the silane coupling agent treatment liquid. By removing the solvent from the silane coupling agent treatment liquid, the surface of the metal layer (M) or the resin layer (P) is treated with the silane coupling agent. The silane coupling agent chemically bonds the metal layer (M) and the resin layer (P).

[0068] In the above-mentioned step (2), a resin layer (P) that has not been surface-treated is laminated on the surface of the metal layer (M) that has been surface-treated in step (1), or a metal layer (M) that has not been surface-treated is laminated on the resin layer (P) that has been surface-treated in step (1), followed by thermocompression bonding. Among these, step (2) is preferably a step of laminating a resin layer (P) that has not been surface-treated on the surface of the metal layer (M) that has been surface-treated in step (1), followed by thermocompression bonding.

[0069] In the thermocompression bonding step, it is preferable to perform heat press bonding or inter-roll thermocompression bonding. In particular, in the thermocompression bonding step, it is preferable to perform thermocompression bonding by passing a set of structural units between a pair of heating rolls (compression rolls). The temperatures of the pair of heating rolls may be the same or different. Furthermore, the width between the pair of heating rolls can be appropriately adjusted depending on the thickness of the structural units. In this embodiment, the thermocompression bonding step (silane bonding) may be a compression bonding step using rolls, or may be the above-mentioned heat press bonding step. Furthermore, the thermocompression bonding step using rolls and the above-mentioned heat press bonding step may be performed in combination.

[0070] The method for producing a metal-resin bonded body further includes a step of laminating the structural units (PM) or the structural units (PMP). In this embodiment, it is preferable that after laminating the structural units (PM) or the structural units (PMP), heat press bonding is further performed.

[0071] When heat press bonding is further performed after laminating the structural unit (PM) or the structural unit (PMP), it is preferable to perform the heat press bonding at a temperature of the melting point of the resin + 10°C or more, preferably the melting point of the resin + 20°C or more. The time for heat press bonding is preferably 1 minute or more, more preferably 2 minutes or more, and even more preferably 3 minutes or more. Furthermore, the time for heat press bonding is preferably 20 minutes or less, more preferably 15 minutes or less, and even more preferably 10 minutes or less.

[0072] In the step of laminating the structural units (PM), a plurality of PMs that serve as basic structural units are laminated (MP-MP-MP...) to obtain a metal-resin bonded body. Note that in the step of laminating the PMs, the PM that is laminated last may be turned over, or a metal layer may be further laminated thereon to form an MP-MP-MP...M structure, with both outermost layers being metal layers (M).

[0073] In the step of laminating the structural units (PMP), a plurality of prepared PMPs serving as basic structural units are laminated (PMP-PMP-PMP...) to obtain a metal-resin bonded body. Note that in the step of laminating the PMPs, metal layers may be further laminated as both surface layers finally to obtain a structure of M-PMP-PMP-PMP...M, with both outermost layers being metal layers (M). Furthermore, in this embodiment, the structural units (PM) and the structural units (PMP) may be laminated in combination.

[0074] (Configuration of Metal-Resin Joined Body) The configuration of the metal-resin joined body has, as its basic structural unit, a structural unit (PM) in which a resin layer (P) and a metal layer (M) are laminated, or a structural unit (PMP) in which a resin layer (P), a metal layer (M), and a resin layer (P) are laminated. In this embodiment, the metal-resin joined body includes n structural units (PM) or n structural units (PMP), and two or more metal layers (M). Here, n may be an integer of 1 or greater, preferably an integer of 2 or greater, more preferably an integer of 3 or greater, even more preferably an integer of 4 or greater, even more preferably an integer of 5 or greater, and particularly preferably an integer of 6 or greater. Note that the upper limit of n is not particularly limited, but when a thin bus bar is required, n is preferably an integer of 50 or less, more preferably an integer of 40 or less, and even more preferably an integer of 30 or less. The metal-resin joined body of the present invention includes not only metal-resin joined bodies formed by laminating the above-mentioned structural units, but also metal-resin joined bodies formed by simply alternately laminating resin layers (P) and metal layers (M). In this case, the metal-resin bonded body can be understood to contain a plurality of constituent units (PM), and n is the number of constituent units (PM) included when one set is made up of the constituent units (PM).

[0075] For example, the metal-resin bonded body of this embodiment can be construed to include the following structures. Examples include M(PM)n, M(PM)nP, P(PM)n, P(PM)nP, MP(PM)n, MP(PM)nP, (PMP)n, M(PMP)n, M(PMP)nP, M(PMP)nM, P(PMP)n, P(PMP)nP, P(PMP)nPM, P(PMP)nMP, MP(PMP)n, MP(PMP)nM, MP(PMP)nPM, PM(PMP)n, PM(PMP)nM, PM(PMP)nPM, and PM(PMP)nMP. The outermost layer of the metal-resin bonded body is preferably selected in consideration of, for example, adhesion to a member constituting the location where the metal-resin bonded body is incorporated. When the above-mentioned structure contains two or more metal layers (M), each of them may have any structure, and a combination of different metal layers (e.g., a combination of copper and aluminum) may be used.When the above-mentioned structure contains two or more resin layers (P), each of them may have any structure, and different resins, resin blends, and various additives may be used.

[0076] In this embodiment, a metal-resin bonded body capable of carrying a large current can be obtained by stacking multiple resin layers and metal layers in the thickness direction, thereby suppressing the influence of the skin effect and reducing energy loss due to increased inductance. The mechanism by which such a metal-resin bonded body can carry a large current is believed to be as follows. For example, in conventional technology, bus bars are composed of only one or multiple metal plates, and the skin effect tends to cause current to flow unevenly only on the surface of the metal layer. Furthermore, in conventional bus bars where multiple thin metal foils (plates) are stacked as metal layers, the skin effect also occurs when the metal layers come into contact with each other, suppressing the current. This effect is particularly pronounced in high-frequency currents, making it difficult to achieve higher-capacity, higher-speed communication. In contrast, in this embodiment, the skin effect is successfully suppressed by stacking the metal layer (M) via a resin layer (P) corresponding to the insulating layer portion. When multiple metal layers (M) are laminated, current flows through each metal layer, resulting in a higher current density, making it possible to pass a larger current than in conventional laminates consisting of a single metal plate or metal layers. This tendency becomes more pronounced as the constituent units of the metal-resin bonded body become more multilayered.

[0077] The total thickness of the metal-resin bonded body is preferably 0.5 mm or more, more preferably 1.0 mm or more. Meanwhile, the upper limit of the total thickness of the metal-resin bonded body is preferably 5.0 mm or less, more preferably 4.0 mm or less, and even more preferably 3.0 mm or less. As described above, the metal-resin bonded body of the present invention is formed by laminating the metal layers (M) constituting the metal-resin bonded body while keeping the proportion of the resin layer (P) within a predetermined range. This allows the structural units (PM) to be multi-layered in the thickness direction (n = 1, 2, 3, 4, ...), thereby suppressing the influence of the skin effect and energy loss due to increased inductance, thereby achieving excellent electrical characteristics. Furthermore, by appropriately controlling the total thickness of the metal-resin bonded body and the thickness of the resin layer, heat dissipation from the metal layer can be promoted, thereby suppressing heat generation. Furthermore, the metal-resin bonded body of this embodiment, which includes the resin layer, can be lightweight and has excellent bending processability.

[0078] (Bus Bar) The metal-resin bonded product of this embodiment is preferably used for a bus bar. This embodiment may also relate to a bus bar including the metal-resin bonded product described above. The bus bar of this embodiment is preferably used for various power module applications, such as wiring between and within units such as motors, inverters, and batteries used in hybrid electric vehicles (HEVs) or electric vehicles (EVs) that require a large-capacity power source; a replacement for main wiring in control panels used in industrial equipment, electrical lines in power receiving panels; electrical lines in large-current devices for electrolytic refining; data centers (distributing power to server racks and other important equipment); renewable energy systems (distributing power generated by solar panels or wind turbines in photovoltaic or wind power generation facilities to power grids or storage systems); transportation systems (distributing power to various parts of vehicles in various transportation systems such as trains, trams, and electric buses); and telecommunications equipment (distributing power to various components in telecommunications equipment and facilities).

[0079] When the metal-resin bonded body of this embodiment is used as a bus bar, the bus bar preferably includes a plate- or rod-shaped main body having at least one bendable portion, and a terminal portion provided at at least one end of the main body and formed seamlessly and integrally with the main body using the same material. The metal-resin bonded body of this embodiment is characterized by excellent processability, eliminating the need to weld or crimp a separate terminal portion to the main body to form the terminal portion, as in conventional methods. Furthermore, the bendable portion preferably has at least one portion that is flexible enough to be bent three-dimensionally by edgewise bending, flatwise bending, or the like.

[0080] (Laminate for Manufacturing Busbars) This embodiment may relate to a laminate for manufacturing busbars, in which one resin layer (P) and one metal layer (M) are bonded together directly or via an adhesion aid film. This embodiment may also relate to a laminate for manufacturing busbars, in which another metal layer (M) is further bonded onto the resin layer (P) directly or via an adhesion aid film. That is, the laminate for manufacturing busbars is a laminate consisting of a resin layer (P) / metal layer (M), or a laminate consisting of a resin layer (P) / metal layer (M) / resin layer (P).

[0081] In the busbar manufacturing laminate of this embodiment, the resin layer (P) and the metal layer (M) are preferably bonded directly or via an adhesion aid film. When the resin layer (P) and the metal layer (M) are bonded directly, no other layer is present between the resin layer (P) and the metal layer (M). In this specification, the adhesion aid film refers to a coating provided between the resin layer (P) and the metal layer (M), and such a coating is to be distinguished from an adhesive layer provided to bond the resin layer and the metal layer. Specifically, the thickness of the adhesion aid film is preferably 1 μm or less, more preferably 0.8 μm or less, even more preferably 0.6 μm or less, even more preferably 0.5 μm or less, even more preferably 0.3 μm or less, and particularly preferably 0.1 μm or less.

[0082] In this embodiment, the adhesion aid film does not substantially contain adhesive polymers contained in so-called adhesive layers. More specifically, the weight-average molecular weight of the components constituting the adhesion aid film is preferably 2000 or less, more preferably 1800 or less, even more preferably 1600 or less, and particularly preferably 1400 or less. Thus, the adhesion aid film of this embodiment is preferably a coating containing a low-molecular-weight compound as its main component, rather than a polymer.

[0083] The adhesion aid film preferably contains, as a main component, a structural unit derived from a silane coupling agent, such as the silane coupling agents described above.

[0084] The present invention will now be described in more detail with reference to examples, although the present invention is not limited to the examples described below.

[0085] <Test Example 1> (1) Bending Workability Durability against bending when processing into the shape of a bus bar was evaluated according to the following evaluation criteria: When processing was possible without any problem, without peeling of the resin layer or metal cracking of the metal layer, it was rated as "A", and when problems such as peeling or cracking occurred during processing, it was rated as "C".

[0086] (2) Inductance Measurement A sample (metal-resin bonded body) processed into a bus bar shape or a size of 10 mm × 100 mm was connected to an LCR meter, and the inductance value was measured when an alternating current was passed through it. The frequency was changed from 1 kHz to 1 MHz, and the value at 100 kHz was read. When compared with the metal layer alone (each comparative example) as 100%, an inductance value of 50% or less was rated as "A," a value of more than 50% but less than 90% was rated as "B," and a value of more than 90% was rated as "C."

[0087] (3) Adhesion between Outermost Layer and Polyphenylene Sulfide Film In Example 5, in which the outermost layer was a resin layer, a 0.05 mm polyphenylene sulfide film was superposed on the outermost layer of the obtained metal-resin bonded body, and the bonded body was heated at 320°C for 5 minutes, preheated for 5 minutes, and pressed at 30 kgf / cm using a vacuum heat press. ２ The metal-resin bonded body was fused by hot pressing under the conditions of 10 mm width. Then, a 180° peel test was performed at a width of 10 mm to evaluate the adhesion between the resin layer, which was the outermost layer of the metal-resin bonded body, and the polyphenylene sulfide film. During the peel test, a 0.025 mm polyimide film was partially sandwiched between the two so that the edges were not bonded and served as a gripping area during the peel test. When the polyphenylene sulfide film broke without peeling occurring at the fused portion, it was determined that there was sufficient adhesion between the resin layer surface, which was the outermost layer of the metal-resin bonded body, and the polyphenylene sulfide film, and the result was rated as "A."

[0088] The raw materials used in Test Example 1 are as follows. <Resin layer> (Polyphenylene sulfide film) (a) Copolymerized polyphenylene sulfide Thickness: 0.020 mm (b) Laminate of copolymerized polyphenylene sulfide and polyphenylene sulfide Copolymerized polyphenylene sulfide / polyphenylene sulfide / copolymerized polyphenylene sulfide Thickness: 0.038 mm (Polyamide film) (c) Nylon 6 Thickness: 0.020 mm (Polypropylene film) (d) Film with a mixing ratio of polypropylene / maleic anhydride-modified polypropylene / styrene-olefin elastomer of 80 / 5 / 15 wt % Thickness: 0.020 mm (Polyethylene film) (e) Ultra-high molecular weight polyethylene Thickness: 0.030 mm

[0089] <Adhesive layer> (f) Ethylene-vinyl acetate copolymer film Thickness: 0.030 mm

[0090] <Metal layer> (g) Copper C1020P-1 / 4H Thickness: 0.10 mm (h) Copper C1020R-1 / 2H Thickness: 0.10 mm (i) Copper C1020R-1 / 2H Thickness: 1.8 mm (j) Copper C1020P-1 / 2H Thickness: 2.0 mm (k) Aluminum A1100P-H16 Thickness: 0.27 mm, phosphate chromate treatment

[0091] [Example 1] Sixteen sheets of (g) as the metal layer and 15 sheets of (a) as the resin layer were cut into A4 size and stacked alternately so that the outermost layers were (g) as shown in Figure 1. Then, in a heat press, the heating temperature was 270°C, the preheating time was 5 minutes, the pressing time was 5 minutes, and the pressure was 30 kgf / cm. ２ The resultant metal-resin bonded body was subjected to heat pressing under the conditions of 10 mm × 100 mm. The metal-resin bonded body was thus obtained, containing 15 structural units (PM) each including a laminate of a resin layer (P) and a metal layer (M), and further containing a metal layer (M) as an outermost layer. The resulting metal-resin bonded body was cut into a size of 10 mm × 100 mm, and silver paste was applied to the cross section to electrically connect the metal layers, after which the inductance was measured.

[0092] [Example 2] Sixteen sheets of (g) as the metal layer and 15 sheets of (d) as the resin layer were cut into A4 size and stacked alternately so that the outermost layers were (g) as shown in Figure 3. Then, in a heat press, the heating temperature was 205°C, the preheating time was 5 minutes, the pressing time was 5 minutes, and the pressure was 30 kgf / cm. ２ The resultant metal-resin bonded body was subjected to heat pressing under the conditions of 10 mm × 100 mm. The metal-resin bonded body was thus obtained, containing 15 structural units (PM) each including a laminate of a resin layer (P) and a metal layer (M), and further containing a metal layer (M) as an outermost layer. The resulting metal-resin bonded body was cut into a size of 10 mm × 100 mm, and silver paste was applied to the cross section to electrically connect the metal layers, after which the inductance was measured.

[0093] [Example 3] Ten sheets of (g) as the metal layer and nine sheets of (c) as the resin layer were cut out to a length of 270 mm and a width of 210 mm, and were alternately stacked so that both outermost layers were (g) as shown in Figure 4. Thereafter, they were heated at 260°C, preheated for 5 minutes, pressed for 5 minutes, and pressed at a pressure of 30 kgf / cm in a vacuum heat press. ２ The metal resin bonded body was thus obtained, which included nine structures (PM) in which the resin layer (P) and the metal layer (M) were laminated, and further included a metal layer (M) as the outermost layer. The metal resin bonded body was cut into a bus bar shape, and the cross section was subjected to soldering to electrically connect the metal layers, and then the inductance was measured.

[0094] [Example 4] Hydrolyzed 3-aminopropyltriethoxysilane was mixed with water and ethanol to adjust the concentration to 0.15 wt%, and then applied to one surface of each (k) aluminum layer constituting the metal layer to a thickness of 15 μm. The water was dried by heating to form an adhesion aid film with a thickness of approximately 22 nm. A (c) 6 nylon layer was rolled out as a resin layer onto the metal layer coated with 3-aminopropyltriethoxysilane, and the layers were thermocompressed between the rolls at a temperature ranging from 210 ° C to 260 ° C to obtain a structural unit (PM) in which the resin layer (P) and the metal layer (M) were laminated. Thereafter, this structural unit (PM) was cut into 270 mm square pieces, and seven sheets were stacked so that the aluminum layer and the 6 nylon layer alternated as shown in FIG. 5. Note that the lamination direction of the seventh sheet was such that the resin layers were joined together so that the outermost layers were aluminum layers. Then, in a vacuum heat press, the heating temperature was 260°C, the preheating time was 5 minutes, the pressure time was 5 minutes, and the pressure was 50 kgf / cm. ２ The heat press was performed under the conditions of

[0043] In this way, a metal-resin bonded body was obtained, which had a configuration in which the resin layer (P) and the metal layer (M) were laminated, contained six (PM), had one metal layer (M) laminated on the resin layer (P) side of the (PM) at one end, and had a resin layer (P) sandwiched between the (PM) and (PM) at the other end (MP / MP / MP / MP / MP / MP / PM when viewed from below). This metal-resin bonded body was cut into a bus bar shape, and the cross section was soldered to conduct the metal layers, and then inductance was measured.

[0095] [Example 5] Nine sheets of (g) as the metal layer and ten sheets of (b) as the resin layer were cut out to a length of 270 mm and a width of 210 mm, and were stacked alternately so that the outermost layers were (b) as shown in Figure 6. Thereafter, they were pressed in a vacuum heat press at a heating temperature of 290°C, a preheating time of 5 minutes, a pressing time of 5 minutes, and a pressure of 30 kgf / cm. ２ The metal resin bonded body was obtained in this manner, including nine structures (PM) in which the resin layer (P) and the metal layer (M) were laminated, and further including the resin layer (P) as the outermost layer. The metal resin bonded body was cut into a bus bar shape, and the cross section was subjected to soldering to electrically connect the metal layers, and then the inductance was measured.

[0096] [Example 6] Eleven sheets of (h) as the metal layer, (f) as the adhesive layer, and (e) as the intermediate layer were stacked in a (f) / (e) / (f) configuration, and these were cut into 10 A4 size sheets as the resin layer, which were stacked alternately so that both outermost layers were (h) as shown in Figure 7. Thereafter, in a heat press, the heating temperature was 160°C, the preheating time was 5 minutes, the pressing time was 5 minutes, and the pressure was 30 kgf / cm. ２ The resulting mixture was subjected to heat pressing under the conditions of 10 mm × 100 mm. In this manner, a metal-resin bonded body was obtained, which included 10 structural units (PM) each including a resin layer (P) including an adhesive layer and a metal layer (M) laminated together, and further including a metal layer (M) as the outermost layer. This metal-resin bonded body was cut into a size of 10 mm × 100 mm, and silver paste was applied to the cross section to electrically connect the metal layers, after which the inductance was measured.

[0097] Comparative Example 1 Only (j) was used and cut into a size of 10 mm x 100 mm, and the inductance was measured.

[0098] Comparative Example 2 Only (i) was used, and cut into a bus bar shape, and inductance was measured.

[0099]

[0100] The bending processability was good in the examples, and Example 5 showed particularly good adhesion to polyphenylene sulfide. When used in conjunction with an external resin component (e.g., a pre-injection-molded resin product), it is preferable for the outermost layer to be resin, which is why this can be considered a favorable result. Furthermore, the examples were confirmed to be less susceptible to the skin effect and to have good electrical properties. Furthermore, all of the examples have a resin layer as a structural unit, which allows for weight reduction. On the other hand, Comparative Examples 1 and 2 were metal layers alone, so the skin effect affected their electrical properties, making them less favorable. In Example 6, the presence of an adhesive layer resulted in an increase in thickness, which was disadvantageous for thinning, and the electrical properties of the metal-resin laminate were somewhat inferior. In Examples 1 to 5, compared to conventional metal-only products, the measured inductance was significantly reduced in the high-frequency range, allowing for larger currents to flow, and thus the electrical properties were favorable. In particular, high-capacity, high-speed communications require higher-frequency currents, and since the skin effect has a greater impact at higher frequencies, such as above 100 kHz, it is extremely beneficial and is expected to contribute to the future field of electronics. Furthermore, reducing inductance also leads to a reduction in switching loss, which has long been an issue in the field of electrical circuits, and is expected to lead to energy savings, component miniaturization, and longer life for electronic components.

[0101] The metal-resin joined body of the present invention suppresses the skin effect, is capable of carrying a large current even in the case of AC, can be lightweight, and has good bending workability. For example, the metal-resin joined body of the present invention is suitable for various power module applications, such as wiring between and within units such as motors, inverters, and batteries used in hybrid electric vehicles (HEVs) or electric vehicles (EVs) that require a large-capacity power source; replacement for main wiring in control panels used in industrial equipment, electrical lines in power receiving panels; and electrical lines in large-current devices for electrolytic refining, and has high industrial value.

[0102] a Resin layer (copolymerized polyphenylene sulfide) b Resin layer (laminate of copolymerized polyphenylene sulfide and polyphenylene sulfide) c Resin layer (nylon 6) d Resin layer (mixed layer of polypropylene / maleic anhydride modified polypropylene / styrene-olefin elastomer) e Resin layer (polyethylene) f Resin layer (ethylene-vinyl acetate copolymer film) g Metal layer (copper) h Metal layer (copper) k Metal layer (aluminum)

Claims

1. A metal resin bonded body including n (where n is an integer of 1 or more) structural units (PM) in which a resin layer (P) and a metal layer (M) are laminated, or structural units (PMP) in which a resin layer (P), a metal layer (M), and a resin layer (P) are laminated, wherein the metal resin bonded body includes two or more metal layers (M).

2. The metal resin bonded body according to claim 1, wherein the total thickness of the metal layer (M) with respect to the total thickness of the metal resin bonded body is 56% or more.

3. The metal resin bonded body according to claim 1, wherein in the structural unit (PM) or the structural unit (PMP), the resin layer (P) and the metal layer (M) are bonded directly or via an adhesion promoter film.

4. The metal resin bonded body according to claim 3, wherein the thickness of the adhesion promoter film is 1 μm or less.

5. The metal resin bonded body according to claim 3, wherein the weight average molecular weight of the component constituting the adhesion promoter film is 2000 or less.

6. The metal resin bonded body according to claim 3, wherein the adhesion promoter film contains a structural unit derived from a silane coupling agent as a main component.

7. The metal resin bonded body according to claim 1, wherein the inductance value when an alternating current of 100 kHz is passed is 90% or less compared to the inductance value when an alternating current of 100 kHz is passed through a single metal layer.

8. The metal resin bonded body according to claim 1, wherein the metal layer (M) contains copper or a copper alloy.

9. The metal resin bonded body according to claim 1, wherein the metal layer (M) contains aluminum or an aluminum alloy.

10. The metal resin bonded body according to claim 1, wherein the resin layer (P) contains a polyphenylene sulfide resin as a main component.

11. The metal resin bonded body according to claim 1, wherein the resin layer (P) contains a polyamide resin as a main component.

12. The metal resin bonded body according to claim 1, wherein the resin layer (P) contains a polypropylene resin as a main component.

13. The metal resin bonded body according to claim 1, wherein the thickness of one layer of the resin layer (P) is 1 to 100 μm.

14. The metal resin bonded body according to claim 1, wherein the thickness of one layer of the metal layer (M) is 0.05 to 2.0 mm.

15. The metal resin bonded body according to claim 1, wherein the total thickness of the metal resin bonded body is 0.5 mm or more.

16. The metal resin bonded body according to claim 1, which is for a bus bar.

17. A bus bar including the metal resin bonded body according to any one of claims 1 to 16.

18. A method for manufacturing a metal-resin bonded body according to any one of claims 1 to 16, comprising obtaining a structural unit (PM) or a structural unit (PMP) by thermocompression bonding the metal layer (M) and the resin layer (P) directly or via an adhesion promoter film.

19. (1) Surface-treating at least one surface selected from the metal layer (M) and the resin layer (P) with a silane coupling agent treatment liquid to form an adhesion promoter film, and (2) laminating the untreated resin layer (P) on the surface-treated metal layer (M) surface, or laminating the untreated metal layer (M) on the surface-treated resin layer (P) and performing thermocompression bonding. The method for manufacturing a metal-resin bonded body according to claim 18.

20. The method for manufacturing a metal-resin bonded body according to claim 18, further comprising laminating the structural unit (PM) or the structural unit (PMP).

21. A laminate for manufacturing a bus bar, in which one resin layer (P) and one metal layer (M) are joined directly or via an adhesion promoter film.

22. The laminate for manufacturing a bus bar according to claim 21, in which another metal layer (M) is further joined directly or via an adhesion promoter film on the resin layer (P).

23. The laminate for manufacturing a bus bar according to claim 21, in which the resin layer (P) and the metal layer (M) are joined via an adhesion promoter film, and the thickness of the adhesion promoter film is 1 μm or less.

24. The laminate for manufacturing a bus bar according to claim 21, in which the weight average molecular weight of the components constituting the adhesion promoter film is 2000 or less.

25. The laminate for manufacturing a bus bar according to claim 21, in which the adhesion promoter film contains, as a main component, a structural unit derived from a silane coupling agent.

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