Electromagnetic wave shielding material, covering material or exterior material, and electric / electronic apparatus

Abstract

The purpose of the present invention is to provide an electromagnetic wave shielding material having good deep drawing moldability and suppressed deformation after molding even with relatively low tensile breaking strain. This electromagnetic wave shielding material 100 includes a laminate in which at least one metal layer 110 and at least one resin layer 160 are laminated. Tensile breaking strain epsilon of the laminate is 80.0% or less, and compression nominal stress sigma when compression nominal strain of the laminate is 30.0% is 190.0 MPa or less.

Description

Electromagnetic shielding material, coating material or exterior material, and electric and electronic equipment

[0001] The present disclosure relates to an electromagnetic shielding material, a coating material or an exterior material, and an electric and electronic equipment.

[0002] The electromagnetic shielding material is used to prevent malfunction of electronic equipment due to electromagnetic noise. For example, in electric vehicles and hybrid vehicles, many adopt a system in which the DC current generated from the mounted secondary battery is converted into an AC current via an inverter, and then the necessary power is supplied to the AC motor to obtain driving force. Electromagnetic waves are generated due to the switching operation of the inverter or the like. In order to prevent reception failures of in-vehicle acoustic equipment, wireless equipment, etc. that may be caused by this electromagnetic wave, the inverter or the battery, motor, etc. together with the inverter are housed in a case made of an electromagnetic shielding material.

[0003] Although a metal plate has been used as such an electromagnetic shielding material, it has low formability and there are weight problems. On the other hand, as an electromagnetic shielding material, a resin composition for insert molding containing a resin and an electromagnetic shielding filler has been proposed (for example, Patent Document 1). When a resin mixed with a conductive filler is used, since the shielding property per thickness is poor, a larger thickness is required to obtain a high shielding effect for magnetic field shielding.

[0004] In order to solve these problems, a laminate of a resin layer and a copper foil has been proposed as an electromagnetic shielding material having excellent formability and capable of weight reduction (for example, Patent Document 2).

[0005] Japanese Unexamined Patent Application Publication No. 2021-055113, Japanese Unexamined Patent Application Publication No. 2021-163789

[0006] Incidentally, electrical and electronic equipment comes in various shapes, and in order to shield against electromagnetic noise, it is necessary to mold the electromagnetic shielding material into various shapes so that the target components can be covered with the electromagnetic shielding material without waste. When a laminate of resin and metal foil is used as an electromagnetic shielding material, it has been confirmed that materials with a relatively large tensile fracture strain in the laminate exhibit good moldability. However, such materials have a relatively large springback, so after molding they try to return to their original shape, causing significant warping and undulation. This raises concerns that electromagnetic waves may leak from the deformed areas, and countermeasures are necessary to address this.

[0007] Therefore, in one embodiment of the present invention, the objective is to provide an electromagnetic wave shielding material that exhibits good deep-draw formability and suppresses deformation after molding, even at relatively low tensile fracture strains.

[0008] The present inventors conducted intensive research to solve the above problems and found that by controlling the tensile fracture strain ε of the laminate to 80.0% or less, and the nominal compressive stress σ when the nominal compressive strain of the laminate is 30.0% to 190.0 MPa or less, it is possible to achieve good deep-draw formability and suppress deformation after molding, even at relatively low tensile fracture strains. The present invention was completed based on the above findings and is illustrated below. [1] An electromagnetic wave shielding material comprising a laminate in which at least one metal layer and at least one resin layer are laminated, wherein the tensile fracture strain ε of the laminate is 80.0% or less, and the nominal compressive stress σ when the nominal compressive strain of the laminate is 30.0% to 190.0 MPa or less. [2] The electromagnetic wave shielding material of [1], wherein the tensile fracture strain ε is 10.0% or more and 50.0% or less. [3] The electromagnetic shielding material of [2] wherein the tensile fracture strain ε is 16.3% or more and 22.0% or less. [4] The electromagnetic shielding material of any of [1] to [3] wherein the nominal compressive stress σ is 100.0 MPa or more and 180.0 MPa or less. [5] The electromagnetic shielding material of [4] wherein the nominal compressive stress σ is 129.0 MPa or more and 173.8 MPa or less. [6] The electromagnetic shielding material of any of [1] to [5] wherein the resin layer contains one or more of the following: polybutylene terephthalate, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, polyamides, modified polyphenylene ether, polypropylene, polyimides, fluororesins, liquid crystal polymers, polyphenylene sulfide, and acrylic resin. [7] The electromagnetic shielding material of [6] wherein the resin layer contains one or more of the following: polybutylene terephthalate and polycarbonate. [8] An electromagnetic shielding material according to any of [1] to [7], wherein the metal layer contains at least one of copper, copper alloy, aluminum, aluminum alloy, iron, and iron alloy. [9] An electromagnetic shielding material according to [8], wherein the metal layer contains copper.

[10] An electromagnetic shielding material according to any of [1] to [9], wherein the thickness of the laminate is 30 μm or more and 1000 μm or less.

[11] An electromagnetic shielding material according to any of [1] to

[10] , wherein the thickness of each layer of the metal layer is 4 μm or more and 150 μm or less.

[12] An electromagnetic shielding material according to any of [1] to

[11] , wherein the thickness of each layer of the resin layer is 20 μm or more and 400 μm or less.

[13] An electromagnetic shielding material according to any of [1] to

[12] , wherein the metal layer is made up of multiple layers and the resin layer is made up of multiple layers.

[14] An electromagnetic shielding material according to

[13] , wherein the number of layers of the metal layer and the number of layers of the resin layer are the same.

[15] An electromagnetic shielding material according to

[14] , wherein the laminate is made up of alternating layers of the metal layer and the resin layer.

[16] A covering or exterior material for electrical and electronic equipment, including an electromagnetic shielding material according to any of [1] to

[15] .

[17] An electrical or electronic equipment equipped with the covering or exterior material according to

[16] .

[0009] In one embodiment of the present invention, it is possible to provide an electromagnetic wave shielding material that exhibits good deep-draw formability and suppresses deformation after molding, even at relatively low tensile fracture strains.

[0010] This is a cross-sectional view showing an example of the electromagnetic shielding material according to the present invention. This is a cross-sectional view showing another example of the electromagnetic shielding material according to the present invention. This is a cross-sectional view showing another example of the electromagnetic shielding material according to the present invention. This is a schematic diagram illustrating a method for preparing a measurement sample used for measuring the tensile fracture strain of a laminate of electromagnetic shielding material according to the present invention. This is a schematic diagram illustrating a method for preparing a measurement sample used for measuring the nominal compressive stress of a laminate of electromagnetic shielding material according to the present invention.

[0011] Preferred embodiments of the present invention will be described below in detail, but the present invention should not be construed as being limited thereto, and various modifications and improvements can be made based on the knowledge of those skilled in the art, without departing from the spirit of the invention. The multiple components disclosed in each embodiment can be combined in appropriate ways to form various inventions. For example, some components may be removed from all the components shown in each embodiment, or components from different embodiments may be combined in appropriate ways.

[0012] [Electromagnetic wave shielding material] The electromagnetic wave shielding material 100 shown in Figure 1 is laminated in the order of metal layer 110 and resin layer 160. The electromagnetic wave shielding material 200 shown in Figure 2 is laminated in the order of metal layer 210, resin layer 260, metal layer 220 and resin layer 270. The electromagnetic wave shielding material 300 shown in Figure 3 is laminated in the order of resin layer 360, metal layer 310, resin layer 370, metal layer 320 and resin layer 380. In other words, these electromagnetic shielding materials 100, 200, and 300 are laminates in which at least one metal layer 110, 210, 220, 310, and 320 and at least one resin layer 160, 260, 270, 360, 370, and 380 are laminated, and have a structure in which at least one layer each of the metal layers 110, 210, 220, 310, and 320 and the resin layers 160, 260, 270, 360, 370, and 380 are alternately laminated. Electromagnetic shielding materials 100, 200, and 300 having such a structure not only have good moldability but also possess electromagnetic shielding effects and heat dissipation properties, and can therefore be used as electromagnetic shielding materials or heat dissipation members. Furthermore, since the electromagnetic wave shielding materials 100, 200, and 300 are constructed by alternately laminating at least one metal layer 110, 210, 220, 310, and 320 with at least one resin layer 160, 260, 270, 360, 370, and 380, the electromagnetic wave shielding materials 100, 200, and 300 can be made lighter compared to a single metal layer of the same thickness.

[0013] (Laminated Structure) Examples of laminated structures for laminates include the following: (1) When the laminated structure consists of two layers, a metal layer / resin layer as shown in Figure 1 is an example. (2) When the laminated structure consists of three layers, examples include metal layer / resin layer / metal layer, resin layer / metal layer / resin layer, resin layer / metal layer / metal layer, and metal layer / resin layer / resin layer. (3) When the laminated structure consists of four layers, in addition to the metal layer / resin layer / metal layer / resin layer shown in Figure 2, examples include metal layer / metal layer / metal layer / resin layer, metal layer / metal layer / resin layer / metal layer, metal layer / metal layer / resin layer / resin layer, and metal layer / resin layer / resin layer / metal layer. (4) If the laminate is composed of three layers, in addition to the resin layer / metal layer / resin layer / metal layer / resin layer shown in Figure 3, for example, metal layer / metal layer / metal layer / metal layer / resin layer, metal layer / metal layer / metal layer / resin layer / metal layer, metal layer / metal layer / metal layer / resin layer / resin layer, metal layer / metal layer / resin layer / metal layer / metal layer, metal layer / metal layer / resin layer / metal layer / resin layer / metal layer, metal layer / resin layer / metal layer / metal layer The following are examples of resin layers, metal layers, resin layers, metal layers, resin layers, metal layers, resin layers, metal layers, resin layers, metal layers, resin layers, metal layers, resin layers, metal layers, resin layers, metal layers, resin layers, metal layers, resin layers, metal layers, resin layers, resin layers, metal layers, resin layers, resin layers, metal layers, resin layers, resin layers, resin layers, metal layers, resin layers, resin layers, resin layers, metal layers, resin layers, resin layers, resin layers, metal layers, resin layers, resin layers.(3) The laminate is composed of six layers, for example, metal layer / resin layer / metal layer / resin layer / metal layer / resin layer, metal layer / metal layer / metal layer / metal layer / metal layer / metal layer / resin layer, metal layer / metal layer / metal layer / metal layer / resin layer / metal layer, metal layer / metal layer / metal layer / metal layer / resin layer / resin layer, metal layer / metal layer / metal layer / resin layer / metal layer / metal layer, metal layer / metal layer / metal layer / resin layer / metal layer / resin layer, metal layer / metal layer / metal layer / resin layer / resin layer / metal layer, metal layer / metal layer / metal layer / resin layer / resin layer / resin layer, metal layer / metal layer / resin layer / metal layer / metal layer / resin layer, metal layer / metal layer / resin layer / metal layer / resin layer / metal layer, metal layer / metal layer / resin layer / metal layer / resin layer / resin layer, metal layer / metal layer / resin layer / resin layer / metal layer / metal layer, metal layer / metal layer / resin layer / resin layer / metal layer / resin layer, metal layer / metal layer / resin layer / Resin layer / resin layer / metal layer, metal layer / metal layer / resin layer / resin layer / resin layer / resin layer, metal layer / resin layer / metal layer / metal layer / metal layer / resin layer, metal layer / resin layer / metal layer / metal layer / resin layer / metal layer, metal layer / Resin layer / metal layer / resin layer / resin layer / metal layer, metal layer / resin layer / resin layer / resin layer / resin layer / metal layer, resin layer / metal layer / metal layer / metal layer / metal layer / resin layer, resin layer / metal layer / metal layer / metal layer / resin layer / tree Examples include a resin layer, a resin layer / metal layer / metal layer / resin layer / resin layer / resin layer, a resin layer / metal layer / metal layer / resin layer / metal layer / resin layer, a resin layer / metal layer / resin layer / metal layer / resin layer / metal layer / resin layer, a resin layer / metal layer / resin layer / metal layer / resin layer / resin layer, a resin layer / metal layer / resin layer / resin layer / resin layer / resin layer, a resin layer / metal layer / resin layer / resin layer / metal layer / resin layer, a resin layer / resin layer / metal layer / resin layer / resin layer. (6) When the composite structure of the composite body consists of seven layers, for example, a resin layer / metal layer / resin layer / resin layer / resin layer / metal layer / resin layer, a resin layer / metal layer / resin layer / metal layer / resin layer / metal layer, a resin layer / resin layer / metal layer / resin layer / metal layer, etc.

[0014] The number of metal layers and resin layers in the laminate is not particularly limited, but as shown in Figure 1, the metal layer 110 and the resin layer 160 may each be a single layer, and as shown in Figures 2-3, the metal layers 210, 220, 310, 320 and the resin layers 260, 270, 360, 370, 380 may each be multiple layers. Furthermore, the difference in the number of metal layers and resin layers in the laminate is not particularly limited, but as shown in Figures 1-2, the number of metal layers 110, 210, 220 may be the same as the number of resin layers 160, 260, 270, and as shown in Figure 3, the number of metal layers 310, 320 may be different from the number of resin layers 360, 370, 380.

[0015] (Overall Thickness) From the viewpoint of moldability, the thickness of the laminate of electromagnetic wave shielding material 100, 200, and 300 is, for example, 30 μm or more, or for example, 100 μm or more, or for example, 200 μm or more. However, from the viewpoint of lightness and processability, the thickness of the above laminate is, for example, 1000 μm or less, or for example, 500 μm or less, or for example, 400 μm or less. The thickness of the laminate can be determined in accordance with Method A in JIS K 6250:2019, by measuring the thickness at each point by clamping four points on the surface of the sheet sample with an indenter with a measuring force of 1.22 N, and averaging the measured values. A constant pressure thickness tester (THICKNESS METER B-1, manufactured by Toyo Seiki Seisakusho Co., Ltd.) or an equivalent device is used for measurement.

[0016] (Tensile Fracture Strain) The tensile fracture strain ε of the laminate of electromagnetic wave shielding materials 100, 200, and 300 is 80.0% or less. In one embodiment, this range suppresses warping, undulation, etc., that occur when the electromagnetic wave shielding material tries to return to its original shape due to springback after deep drawing, for example. As a result, leakage of electromagnetic waves that may occur from warped or undulating parts can be avoided. From the viewpoint of suppressing the amount of springback of the material, the upper limit of the tensile fracture strain ε is preferably 50.0% or less, and more preferably 22.0% or less. On the other hand, from the viewpoint of avoiding brittle fracture, the lower limit of the tensile fracture strain ε is preferably 10.0% or more, and more preferably 16.3% or more.

[0017] (Method for measuring tensile fracture strain) The tensile fracture strain will be tested in accordance with ASTM D882. The measurement will be performed using an Autograph (AGS-X) manufactured by Shimadzu Corporation or an equivalent device. As an example, the method for measuring the tensile fracture strain when an electromagnetic wave shielding material, in which the metal layer is composed of rolled metal foil, is used as the measurement sample will be described below. First, as shown in Figure 4, the electromagnetic wave shielding material is cut to a size of 160 mm x 12.7 mm using a precision cutting machine in accordance with ASTM D882 so that the rolling direction of the rolled metal foil is the longitudinal direction A, thereby obtaining a measurement sample 10. A JDC Precision Cutter manufactured by Thwing-Albert or an equivalent device is used as the cutting machine. The Autograph's two grips are used to grip the gripping area 11 and 12 of the measurement sample 10 (from the edges 13 and 14 in the longitudinal direction A to 30 mm toward the opposite edge 13 and 14) and set in place. The test is conducted at room temperature maintained at 20-25°C. The tensile speed is 50 mm / min. Tensile tension is applied until part or all of the material of the measurement sample 10 breaks. Three trials are performed. A stress-strain diagram is obtained from the Autograph, and the average value of the tensile fracture strain is calculated.

[0018] (Nominal Compression Stress) From the viewpoint of improving moldability, the nominal compression stress σ of the laminate of electromagnetic wave shielding materials 100, 200, and 300 is 190.0 MPa or less when the nominal compression strain is 30.0%. In one embodiment, being within this range reduces the holding pressure and friction during deep drawing due to the yielding of the resin layer during molding, making it easier for the electromagnetic wave shielding material to be drawn in. Therefore, even if the electromagnetic wave shielding material has a relatively low tensile fracture strain, it can exhibit high deep drawing moldability and suppress the amount of springback. Relatively low tensile fracture strain means, for example, a tensile fracture strain of 80.0% or less. From the viewpoint of yielding the resin layer during molding, the nominal compression stress σ is preferably 180.0 MPa or less, more preferably 173.8 MPa or less, as an upper limit. On the other hand, the nominal compressive stress σ is preferably 100.0 MPa or higher, and more preferably 129.0 MPa or higher, from the viewpoint that if it is extremely low, the restraining pressure will not function and fracture or wrinkling will easily occur.

[0019] (Method for measuring compressive nominal stress) The compressive nominal stress is measured using an Autograph (AG-100kNG) manufactured by Shimadzu Corporation or an equivalent device. The method for measuring the compressive nominal stress in accordance with JIS K 7181:2011 is described below. First, sample 20 is obtained by cutting the electromagnetic shielding material 100, 200, and 300 into 20 mm x 20 mm pieces, as shown in Figure 5(A). As shown in Figure 5(B), a measurement sample 30 with a total thickness of approximately 4 mm is obtained by stacking the sample 20 pieces. The number of sample 20 pieces to be stacked is an integer obtained by dividing 4 mm by the thickness of the sample 20 (mm) and rounding the value to the first decimal place. For example, if the thickness of the sample 20 is 0.260 mm, the number is 15 pieces, calculated using the formula: 4 ÷ 0.260. After placing the sample 30 for measurement on the pressure plate of the autograph, it is compressed until the nominal stress σ reaches 250 MPa or the sample 30 is pushed vertically downward by 3 mm. The test is performed at room temperature maintained at 20°C to 25°C. To eliminate the effect of gaps in the material, the position where the nominal stress reaches 1.25 MPa is set as the compression origin. The compression rate is 0.5 mm / min. A stress-strain diagram is obtained from the autograph, and the nominal compression stress when the nominal compression strain is 30.0% is determined.

[0020] <Metal Layer> (Shape) The shape of metal layers 110, 210, 220, 310, and 320 is not particularly limited, but examples include metal foils such as rolled metal foil and electrolytic metal foil.

[0021] (Metallic Material) There are no particular restrictions on the metallic material constituting the metal layers 110, 210, 220, 310, and 320, but it is preferable that it contains at least one of copper, copper alloys, aluminum, aluminum alloys, iron, and iron alloys. Among these, it is more preferable that it contains copper. From the viewpoint of electromagnetic wave shielding properties, the conductivity should be 1.0 × 10⁻⁶. 6Materials with a density of S / m or higher are desirable. Metal layers 110, 210, 220, 310, and 320 may consist of copper foil. When copper foil is used as metal layers 110, 210, 220, 310, and 320, a high purity of copper is preferred because it improves shielding properties, with a purity of preferably 99.5% by mass or higher, and more preferably 99.8% by mass or higher. Rolled copper foil, electrolytic copper foil, metallized copper foil, etc. can be used as copper foil, but rolled copper foil with excellent formability is preferred. When alloying elements are added to copper foil to form copper alloy foil, the total content of these elements and unavoidable impurities should be less than 0.5% by mass. In particular, it is preferable to include in the copper foil a total of 50 to 2000 ppm by mass of one or more of the following elements: tin, manganese, chromium, zinc, zirconium, magnesium, nickel, silicon, and silver, and / or 10 to 50 ppm by mass of phosphorus, as this improves the elongation compared to pure copper foil of the same thickness.

[0022] (Thickness) The thickness of each metal layer 110, 210, 220, 310, and 320 is, for example, 4 μm or more at the lower limit and 9 μm or more at the upper limit. On the other hand, the thickness of each metal layer is, for example, 150 μm or less and 70 μm or less at the upper limit. The thickness of the metal layers 110, 210, 220, 310, and 320 can be measured using the same method as the thickness of the electromagnetic shielding materials 100, 200, and 300. If the thickness of the metal layers 110, 210, 220, 310, and 320 in the electromagnetic shielding materials 100, 200, and 300 is to be measured by observing the thickness cross-section with an SEM or similar device.

[0023] (Heat Treatment) The metal layers 110, 210, 220, 310, and 320 exhibit excellent moldability upon heat treatment. The heat treatment conditions are preferably carried out under vacuum or in a deoxygenated atmosphere such as nitrogen at a temperature in the range of 200 to 400°C for 30 minutes to 24 hours. The metal layers 110, 210, 220, 310, and 320 may be laminated onto the resin layers 160, 260, 270, 360, 370, and 380 after heat treatment.

[0024] (Surface Treatment Film) From the viewpoint of stably improving adhesion and moldability with the resin layers 160, 260, 270, 360, 370, and 380, although not shown in the figures, at least one surface of the metal layers 110, 210, 220, 310, and 320 (the surface in contact with the resin layer) may have a surface treatment film containing Ni. In addition to Ni, the surface treatment film may also contain Cr and / or Zn. The amounts of Cr, Zn, and Ni in the surface treatment film are not particularly limited, but can be adjusted as appropriate.

[0025] The surface treatment film can be composed of, for example, a heat-resistant treatment film and / or a chromate treatment film.

[0026] The heat-resistant treatment film is not particularly limited and can be formed from materials known in the art. Since the heat-resistant treatment film may also function as a rust-preventive film, a single film possessing both heat-resistant and rust-preventive functions may be formed. The heat-resistant treatment film and / or rust-preventive film may contain one of the following (in any form such as metal, alloy, oxide, nitride, sulfide, etc.) or a combination of two or more: nickel, zinc, tin, cobalt, molybdenum, copper, tungsten, phosphorus, arsenic, chromium, vanadium, titanium, aluminum, gold, silver, platinum group elements, iron, and tantalum. An example of a heat-resistant treatment film and / or rust-preventive film is a film containing a nickel-zinc alloy. The heat-resistant treatment film and rust-preventive film can be formed by electroplating. The conditions for this are not particularly limited, but typical conditions for a heat-resistant treatment film (Ni-Zn film) are as follows. Plating solution composition: 1-30 g / L Ni, 1-30 g / L Zn Plating solution pH: 2-5 Plating solution temperature: 30-50°C Electroplating conditions: Current density 0.1-10 A / dm 2 Time: 0.1 to 5 seconds. Number of electroplating treatments: 1 or more times.

[0027] The chromate-treated film is not particularly limited and can be formed from materials known in the art. Hereinafter, "chromate-treated film" means a film formed with a solution containing chromic anhydride, chromic acid, dichromate, chromate, or dichromate. The chromate-treated film may contain one element (in any form such as metal, alloy, oxide, nitride, or sulfide) or a combination of two or more elements from among cobalt, iron, nickel, molybdenum, zinc, tantalum, copper, aluminum, phosphorus, tungsten, tin, arsenic, and titanium. Examples of chromate-treated films include chromate-treated films treated with an aqueous solution of chromic anhydride or potassium dichromate, and chromate-treated films treated with a treatment solution containing chromic anhydride or potassium dichromate and zinc.

[0028] Chromate-treated films can be formed by electrolytic chromate treatment or immersion chromate treatment. While the conditions for these chromate treatments are not particularly limited, typical conditions for chromate-treated films are as follows: Chromate solution composition: 1-10 g / L of K2Cr2O7, 0.01-10 g / L of Zn; Chromate solution pH: 2-5; Chromate solution temperature: 30-55°C; Electrolytic conditions: Current density 0.1-10 A / dm² 2 Time: 0.1 to 5 seconds (If immersion is performed without power, immersion time: 0.1 to 5 seconds) Number of chromate treatments: 1 or more times

[0029] The surface treatment film may include a heat-resistant film and a chromate treatment film, as well as known films such as silane coupling treatment films, within a range that does not impede the effects of the present invention. The silane coupling treatment film is not particularly limited and can be formed from materials known in the art. Hereinafter, "silane coupling treatment film" means a film formed from a silane coupling agent. The silane coupling agent is not particularly limited and can be any known in the art. Examples of silane coupling agents include amino silane coupling agents, epoxy silane coupling agents, mercapto silane coupling agents, methacryloxy silane coupling agents, vinyl silane coupling agents, imidazole silane coupling agents, and triazine silane coupling agents. Among these, amino silane coupling agents and epoxy silane coupling agents are preferred. The above-mentioned silane coupling agents can be used individually or in combination of two or more.

[0030] Silane coupling agents can be manufactured by known methods, but commercially available products may also be used. Examples of commercially available silane coupling agents include the KBM series and KBE series manufactured by Shin-Etsu Chemical Co., Ltd. Commercially available silane coupling agents may be used individually, but from the viewpoint of adhesion (peel strength) between the surface treatment film and the resin substrate, it is preferable to use a mixture of two or more silane coupling agents. Among these, preferred silane coupling agent mixtures are a mixture of KBM603 (N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) and KBM503 (3-methacryloxypropyltrimethoxysilane), a mixture of KBM602 (N-2-(aminoethyl)-3-aminopropyldimethoxysilane) and KBM503 (3-methacryloxypropyltrimethoxysilane), a mixture of KBM603 (N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) and KBE503 (3-methacryloxypropyltriethoxysilane), and KBM602 (N-2-(aminoethyl)-3-aminopropyldimethoxysilane) The mixtures include a mixture of silane (3-

[0031] Furthermore, when forming multiple metal layers, all metal layers may be made of the same material, or different materials may be used for each layer. Also, all metal layers may have the same thickness, or different thicknesses may be used for each layer.

[0032] <Resin Layer> The shape of the resin layers 160, 260, 270, 360, 370, and 380 is not particularly limited, but examples include a film shape. When the resin layer is in the form of a film, the film is not particularly limited, but examples include an unoriented film, a uniaxially oriented film, and a biaxially oriented film. Furthermore, in order to produce a laminate in which the tensile fracture strain ε is 80.0% or less, for example, a resin layer with a relatively large tensile fracture strain and a metal layer with a relatively low tensile fracture strain may be used, or for example, a resin layer with a relatively small tensile fracture strain and a metal layer with a relatively low tensile fracture strain may be used, or for example, a resin layer with a relatively large tensile fracture strain and a resin layer with a low tensile fracture strain and a metal layer with a relatively low tensile fracture strain may be used. In particular, from the viewpoint of further lowering the tensile fracture strain ε of the laminate, at least one of the outermost layers of the laminate may be a metal layer.

[0033] (Resin Material) The resin layers 160, 260, 270, 360, 370, and 380 are not particularly limited in terms of resin material, but it is preferable that they contain one or more combinations of polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamides (PA), modified polyphenylene ether (m-PPE), polypropylene (PP), polyimides (PI), fluororesins such as perfluoroalkoxyalkane polymers (PFA) and polytetrafluoroethylene (PTFE), liquid crystal polymers (LCP), polyphenylene sulfide (PPS), and acrylic resins such as polymethyl methacrylate resin (PMMA). In particular, from the viewpoint of suppressing warping and undulation, it is more preferable that the resin layers 160, 260, 270, 360, 370, and 380 contain one or more combinations of polybutylene terephthalate and polycarbonate. Furthermore, from the viewpoint of heat dissipation, the resin layers 160, 260, 270, 360, 370, and 380 may contain metal powders such as copper and aluminum, fillers, and inorganic powders such as carbon and graphite. The content of inorganic powder in the resin layers 160, 260, 270, 360, 370, and 380 is not particularly limited, but is, for example, 95% by volume or less.

[0034] (Thickness of the resin layer) The thickness of each layer of the above resin layers 160, 260, 270, 360, 370, and 380 is, for example, 20 μm or more at the lower limit and 50 μm or more at the upper limit. On the other hand, the thickness of each layer is, for example, 400 μm or less and 250 μm or less at the upper limit. The thickness of the resin layers 160, 260, 270, 360, 370, and 380 can be measured using the same method as the thickness of the electromagnetic wave shielding materials 100, 200, and 300.

[0035] Furthermore, when forming multiple resin layers 160, 260, 270, 360, 370, and 380, all resin layers 160, 260, 270, 360, 370, and 380 may be made of the same material, or different materials may be used for each layer. Also, all resin layers 160, 260, 270, 360, 370, and 380 may have the same thickness, or the thickness may differ for each layer.

[0036] Furthermore, the ratio (MT / RT) of the thickness per layer (MT) of the metal layers 110, 210, 220, 310, and 320 to the thickness per layer (RT) of the resin layers 160, 260, 270, 360, 370, and 380 is not particularly limited, but is, for example, 0.05 or more and 0.40 or less, or for example, 0.18 or more and 0.35 or less.

[0037] (Lamination method) As a means of laminating the metal layers 110, 210, 220, 310, 320 with the resin layers 160, 260, 270, 360, 370, 380, an adhesive may be used between the metal layers 110, 210, 220, 310, 320 and the resin layers 160, 260, 270, 360, 370, 380, or the resin layers 160, 260, 270, 360, 370, 380 may be heat-pressed onto the metal layers 110, 210, 220, 310, 320 without using an adhesive. A method of simply stacking without using an adhesive is also acceptable, but considering the integrity of the laminate, it is preferable to join at least the edges (for example, each side if the laminate is rectangular) with tape, adhesive, or by heat-pressing. There are no particular restrictions on the adhesive, but examples include acrylic resins, epoxy resins, urethanes, polyesters, polycarbonates, silicone resins, vinyl acetates, styrene-butadiene rubbers, nitrile rubbers, phenolic resins, and cyanoacrylates. For ease of manufacture and cost reasons, urethane, polyester, and vinyl acetate adhesives are preferred. From the viewpoint of heat dissipation, the adhesive may contain thermally conductive inorganic powders such as alumina, metal powders, powders such as carbon and graphite, or fillers. The content of inorganic powder in the adhesive is not particularly limited, but for example, it is 95% by mass or less.

[0038] (Applications) In one embodiment, it can be used for various electromagnetic shielding applications, particularly as a covering or exterior material for electrical and electronic equipment (e.g., inverters, communication devices, resonators, electron tubes / discharge lamps, electric heating equipment, electric motors, generators, electronic components, printed circuits, medical devices, etc.), covering material for harnesses and communication cables connected to electrical and electronic equipment, electromagnetic shielding sheets, electromagnetic shielding panels, electromagnetic shielding bags, electromagnetic shielding boxes, electromagnetic shielding rooms, etc.

[0039] The present invention will be specifically described based on examples and comparative examples. The following descriptions of examples and comparative examples are merely specific examples to facilitate understanding of the technical content of the present invention, and the technical scope of the present invention is not limited by these examples.

[0040] [Preparation of Electromagnetic Wave Shielding Material] In Examples 1 to 6 and Comparative Examples 1 to 8, the materials shown in Table 1 were prepared, and an electromagnetic wave shielding material was prepared according to the configuration shown in Table 2. Also, for the metal layer A shown in Table 1, rolled copper foil was used, and for the metal layer B, rolled aluminum foil was used. The rolled copper foil was heat-treated at 300 °C for 1 hour in a nitrogen-reduced atmosphere. The rolled aluminum foil was heat-treated at 350 °C for 1 hour in a nitrogen-reduced atmosphere. Hereinafter, a specific manufacturing method will be described. The thicknesses of the respective materials shown in Table 1 were measured according to the method described above. The results are shown in Table 1.

[0041] In the preparation of the electromagnetic wave shielding materials of Examples 1 to 6 and Comparative Examples 1 to 8, according to the configuration shown in Table 2, a two-component mixed adhesive (main component: SD2, curing agent: H-5) manufactured by Rock Paint Co., Ltd. was used to laminate the metal layer and the resin layer, respectively. After applying the adhesive to the metal layer using a bar coater so that the thickness after drying would be 3 to 7 μm, the resin layer was laminated on the coated surface. For curing of the adhesive, it was left standing at 40 °C for 1 week after lamination.

[0042] The following characteristic evaluations were performed on the electromagnetic wave shielding materials of Examples 1 to 6 and Comparative Examples 1 to 8 prepared above.

[0043] <Tensile Rupture Strain>For the electromagnetic wave shielding materials of Examples 1 to 6 and Comparative Examples 1 to 8, the tensile rupture strain was measured. The measurement method shall follow the method described above. The results are shown in Table 2. For reference, the tensile rupture strains of the metal layers A to B and the resin layers C to E shown in Table 1 were also measured. The results are shown in Table 1.

[0044] <Compressive Nominal Stress>For the electromagnetic wave shielding materials of Examples 1 to 6 and Comparative Examples 1 to 8, the compressive nominal stress was measured. The measurement method shall follow the method described above. The results are shown in Table 2.

[0045] <Deep drawing formability>For the electromagnetic shielding materials of Examples 1 to 6 and Comparative Examples 1 to 8, the maximum drawing depth was measured. A simple die with a prismatic shape having a surface of 30 mm × 30 mm and a curvature radius R of 6 mm was used. After cutting out the electromagnetic shielding material into a circle with a diameter of φ50 mm to 80 mm to obtain a sample, the sample was placed statically on the lower die. For a sample asymmetric in the thickness direction, the outermost metal layer was placed so as to contact the upper die or the punch. The upper die was placed on the sample, and the upper die and the lower die were fastened with a torque wrench so that the tightening torque amount became 10 N·m with six M6 (JIS B 1176:2014 standard) hexagon socket bolts having a length of 30 mm. The punch was installed on the upper die and pushed in at a test speed of 900 mm / min to a certain stroke with a compression device. The maximum drawing depth amount was obtained by adjusting the sample diameter at 2 mm intervals and the drawing depth amount at 1 mm intervals so as not to break while leaving a 2 mm to 3 mm flange. The results are shown in Table 2.

[0046] <W bending test>For the electromagnetic shielding materials of Examples 1 to 6 and Comparative Examples 1 to 8, the springback amount was measured. Regarding the measurement method, it was tested using a jig compliant with the bending test in JIS H 3100:2018 or the W bending test method in Japan Copper Development Association (JCBA) T307:2007. A test piece for measurement was obtained by cutting a 50 mm × 10 mm size so that the rolling direction of the rolled metal foil became the longitudinal direction. The W bending test jig was placed in a compression device, and the test piece was placed statically. For a sample asymmetric in the thickness direction, the outermost metal layer was placed so as to contact the lower die. Thereafter, it was pressurized at a load of 20 kN for 1 second. AGX-50kN V2D manufactured by Shimadzu Corporation was used as the compression device. The test piece after pressurization was observed with an optical microscope. VH-X8000 manufactured by Keyence Corporation was used as the optical microscope. The cross section of the central part that becomes the convex part in the W bending process was observed. The springback amount was obtained by subtracting the die angle of 90° from the angle formed by the convex part. The results are shown in Table 2.

[0047] (Judgment Criteria) In this case, if the maximum excavation depth was 15 mm or more and the springback amount was 20° or less, it was judged to have excellent formability and springback properties. On the other hand, in all other cases, it was judged to have poor formability or springback properties.

[0048]

[0049]

[0050] As can be seen from the above results, according to the embodiments of the present invention, it is possible to provide an electromagnetic wave shielding material with excellent formability even at relatively low tensile fracture strains. More specifically, it has good deep-draw formability and can suppress deformation after molding.

[0051] (Potential Contribution to SDGs) According to the above embodiment, it is possible to provide an electromagnetic shielding material that exhibits good deep-draw formability even at relatively low tensile fracture strains and suppresses deformation after forming, thus potentially improving product yield in the manufacture of electronic devices and the like. Improved product yield leads to a stable supply of products and a reduction in the loss of metal raw materials, which are limited resources. For this reason, the above embodiment has the potential to contribute to Goal 9, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation," and Goal 12, "Ensure sustainable consumption and production patterns," of the United Nations-led Sustainable Development Goals (SDGs).

[0052] 10, 30 Measurement sample 11, 12 Grip area 13, 14 Edge 20 Sample 100, 200, 300 Electromagnetic shielding material 110, 210, 220, 310, 320 Metal layer 160, 260, 270, 360, 370, 380 Resin layer

Claims

1. An electromagnetic shielding material comprising a laminate in which at least one metal layer and at least one resin layer are laminated, wherein the tensile fracture strain ε of the laminate is 80.0% or less, and the nominal compressive stress σ of the laminate when the nominal compressive strain is 30.0% is 190.0 MPa or less.

2. The electromagnetic wave shielding material according to claim 1, wherein the tensile fracture strain ε is 10.0% or more and 50.0% or less.

3. The electromagnetic wave shielding material according to claim 2, wherein the tensile fracture strain ε is 16.3% or more and 22.0% or less.

4. The electromagnetic wave shielding material according to any one of claims 1 to 3, wherein the nominal compressive stress σ is 100.0 MPa or more and 180.0 MPa or less.

5. The electromagnetic wave shielding material according to claim 4, wherein the nominal compressive stress σ is 129.0 MPa or more and 173.8 MPa or less.

6. The electromagnetic wave shielding material according to any one of claims 1 to 5, wherein the resin layer contains one or more of the following: polybutylene terephthalate, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, polyamides, modified polyphenylene ether, polypropylene, polyimides, fluororesins, liquid crystal polymers, polyphenylene sulfide, and acrylic resins.

7. The electromagnetic wave shielding material according to claim 6, wherein the resin layer contains one or a combination of two of polybutylene terephthalate and polycarbonate.

8. The electromagnetic wave shielding material according to any one of claims 1 to 7, wherein the metal layer contains at least one of copper, copper alloy, aluminum, aluminum alloy, iron, and iron alloy.

9. The electromagnetic wave shielding material according to claim 8, wherein the metal layer contains copper.

10. The electromagnetic wave shielding material according to any one of claims 1 to 9, wherein the thickness of the laminate is 30 μm or more and 1000 μm or less.

11. The electromagnetic wave shielding material according to any one of claims 1 to 10, wherein the thickness of each layer of the metal layer is 4 μm or more and 150 μm or less.

12. The electromagnetic wave shielding material according to any one of claims 1 to 11, wherein the thickness of each layer of the resin layer is 20 μm or more and 400 μm or less.

13. The electromagnetic wave shielding material according to any one of claims 1 to 12, wherein the metal layer is made up of multiple layers and the resin layer is made up of multiple layers.

14. The electromagnetic wave shielding material according to claim 13, wherein the number of metal layers and the number of resin layers are the same.

15. The electromagnetic wave shielding material according to claim 14, wherein the laminate is made up of alternating layers of metal and resin.

16. A covering or exterior material for electrical and electronic equipment, comprising the electromagnetic wave shielding material described in any one of claims 1 to 15.

17. An electrical or electronic device comprising the covering material or exterior material described in claim 16.

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