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

Abstract

Provided is an electromagnetic wave shielding material exhibiting good formability. The electromagnetic wave shielding material includes a first metal layer, a second metal layer, and a stress relaxation layer provided between the first metal layer and the second metal layer. The stress relaxation layer includes a metal layer and / or a resin layer, and the value of elongation at break (%) with respect to the maximum stress (MPa) of the stress relaxation layer is 0.600 or more.

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] In recent years, interest in global environmental issues has been increasing worldwide, and the spread of environmentally friendly vehicles equipped with secondary batteries such as electric vehicles and hybrid vehicles has been progressing. In these vehicles, many electronic components and electronic systems are used, and an electromagnetic shielding material is used to prevent problems caused by electromagnetic wave interference.

[0003] Among them, the electromagnetic shielding material can improve the electromagnetic shielding performance in a wide frequency band by combining a metal foil and a resin film, and is known to be used as a material for shielding electromagnetic waves from components such as substrates and sensors that may malfunction due to electromagnetic noise (for example, Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2010-238870

[0005] By the way, electric and electronic equipment has various shapes, and in order to shield electromagnetic noise, it is required to form the electromagnetic shielding material into various shapes so that the target components can be covered without waste with the electromagnetic shielding material. In an electromagnetic shielding material that combines a metal foil and a resin film, the metal foil and / or the resin layer may be broken by the forming process, and good shielding performance may not be maintained. Therefore, the electromagnetic shielding material is required to have improved formability.

[0006] Therefore, in one embodiment of the present invention, an object is to provide an electromagnetic shielding material having good formability.

[0007] The inventors of the present invention have conducted diligent research to solve the above problems and have found that by controlling the value of the elongation at break (%) of the stress relaxation layer with respect to the maximum stress (MPa) of the stress relaxation layer on the surface of the metal layer (elongation at break of the stress relaxation layer / maximum stress of the stress relaxation layer), the moldability of the electromagnetic wave shielding material can be improved. The present invention was completed based on the above findings and is illustrated below. [1] An electromagnetic wave shielding material comprising a first metal layer, a second metal layer, and a stress relaxation layer provided between the first metal layer and the second metal layer, wherein the stress relaxation layer includes a metal layer and / or a resin layer, and the value of the elongation at break (%) with respect to the maximum stress (MPa) of the stress relaxation layer is 0.600 or more. [2] The electromagnetic wave shielding material according to [1], wherein the value of the elongation at break (%) with respect to the maximum stress (MPa) of the stress relaxation layer is 0.650 or more and 3.000 or less. [3] The electromagnetic shielding material according to [2], wherein the value of the elongation at break (%) of the stress relaxation layer with respect to the maximum stress (MPa) is 0.704 or more and 2.629 or less. [4] The electromagnetic shielding material according to any of [1] to [3], wherein the stress relaxation layer includes a resin layer, and the resin layer of the stress relaxation layer includes one or more of polyethylene terephthalate, polybutylene terephthalate, polypropylene, nylon, polyphenylene sulfide, and urethane. [5] The electromagnetic shielding material according to [1], wherein the stress relaxation layer consists of a resin layer. [6] The electromagnetic shielding material according to [5], wherein the resin layer of the stress relaxation layer comprises a first resin layer, a second resin layer, and a third resin layer in this order. [7] The electromagnetic shielding material according to [6], wherein the resin material of the third resin layer is the same as the resin material of the first resin layer. [8] The electromagnetic shielding material according to [7], wherein the first resin layer and the third resin layer consist of polyethylene terephthalate. [9] The stress-relieving layer is an electromagnetic shielding material according to any of [1] to [4], comprising a resin layer and a metal layer.

[10] The stress-relieving layer comprises at least two resin layers and at least one metal layer, wherein the at least one metal layer is sandwiched between the at least two resin layers, according to the electromagnetic shielding material of [9].

[11] The electromagnetic shielding material of

[10] wherein the at least one metal layer contains one or more of the following: copper, copper alloy, aluminum, aluminum alloy, iron, iron alloy, nickel, and nickel alloy.

[12] The electromagnetic shielding material of any of [1] to

[11] wherein the surface of the first metal layer opposite to the stress relaxation layer has a resin layer arranged as the outermost layer.

[13] The electromagnetic shielding material of any of [1] to

[12] wherein the elongation at break of the stress relaxation layer is 90.0% or more and 200.0% or less.

[14] The electromagnetic shielding material of

[13] wherein the elongation at break of the stress relaxation layer is 104.7% or more and 182.4% or less.

[15] The electromagnetic shielding material of any of [1] to

[14] wherein the maximum stress of the stress relaxation layer is 30.0 MPa or more and 200.0 MPa or less.

[16] The electromagnetic shielding material according to

[15] , wherein the maximum stress of the stress relaxation layer is 48.8 MPa or more and 194.1 MPa or less.

[17] The electromagnetic shielding material according to any of [1] to

[16] , wherein the thickness of the stress relaxation layer is 50 μm or more and 500 μm or less.

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

[17] .

[19] Electrical and electronic equipment equipped with the covering or exterior material according to

[18] .

[0008] In one embodiment of the present invention, an electromagnetic wave shielding material with good moldability can be provided.

[0009] 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 graph showing the relationship between the elongation at break of the stress relaxation layer and the maximum stress of the stress relaxation layer and the stroke at break of the stress relaxation layer in Examples 1 to 10 and Comparative Examples 1 to 6.

[0010] 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.

[0011] [Electromagnetic wave shielding material] The electromagnetic wave shielding material 100 shown in Figure 1 comprises, in this order, a first metal layer 110, a stress relaxation layer 150 on the surface 111 of the first metal layer 110, and a second metal layer 120 on the surface 151 of the stress relaxation layer 150 opposite to the first metal layer 110. The stress relaxation layer 150 is provided between the first metal layer and the second metal layer and includes a metal layer and / or a resin layer from the viewpoint of improving moldability. Furthermore, the electromagnetic wave shielding material 200 shown in Figure 2 differs from the electromagnetic wave shielding material 100 shown in Figure 1 in that, from the viewpoint of further improving moldability, it further comprises resin layers 230 and 240 as the outermost layers, and these resin layers 230 and 240 are provided on the surface 112 of the first metal layer 110 opposite to the stress relaxation layer 150 and on the surface 121 of the second metal layer 120 opposite to the stress relaxation layer 150, respectively. Although not shown in the diagram, one outermost layer of the electromagnetic shielding material may be a resin layer, and the other outermost layer may be a metal layer.

[0012] (Overall Thickness) From the viewpoint of moldability, the thickness of the electromagnetic shielding materials 100 and 200 is, for example, 200 μm or more, 250 μm or more, and 300 μm or more. However, from the viewpoint of lightness and processability, the thickness of the electromagnetic shielding materials 100 and 200 is, for example, 750 μm or less, 700 μm or less, and 650 μm or less. The thickness of the electromagnetic shielding materials 100 and 200 can be measured using a constant pressure thickness tester (THICKNESS METER B-1, manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with Method A in JIS K 6250:2019, by clamping four points on the surface of the sheet sample with an indenter with a measuring force of 1.22 N, measuring the thickness at each point, and then averaging the measured values.

[0013] <Stress Relaxation Layer> The inventors investigated the fracture elongation and maximum stress of the stress relaxation layer on the surface of the metal layer from the viewpoint of improving formability. As a result, they inferred that when the fracture elongation of the stress relaxation layer is relatively small, it cannot follow the deformation during molding, and the formability is not good. On the other hand, they inferred that when the maximum stress of the stress relaxation layer is relatively large, the force applied to the interface between adjacent layers during molding becomes large, and the formability is not good. Furthermore, the inventors found that when the maximum stress of the stress relaxation layer is relatively small or when the fracture elongation of the stress relaxation layer is relatively large, the formability is good. Based on a comprehensive assessment of these factors, they found that if the value of fracture elongation relative to the maximum stress (fracture elongation / maximum stress) in the stress relaxation layer is within a predetermined range, the fracture of the electromagnetic wave shielding material that occurs during molding can be suppressed, and the formability is good. That is, the value of the fracture elongation (%) of the stress relaxation layer 150 relative to the maximum stress (MPa) (fracture elongation / maximum stress) is 0.600 or more. Furthermore, from the viewpoint of further improving moldability, the above value is preferably 0.650 or higher, and more preferably 0.704 or higher. While there is no specific value set for the fracture elongation (%) of the stress relaxation layer 150 relative to the maximum stress (MPa) of the stress relaxation layer 150 (fracture elongation / maximum stress), it is typically 3.000 or less as an upper limit, and more typically 2.629 or less. In this specification, the unit for the fracture elongation (%) of the stress relaxation layer relative to the maximum stress (MPa) of the stress relaxation layer is "% / MPa". However, the value of the fracture elongation (%) of the stress relaxation layer 150 relative to the maximum stress (MPa) (fracture elongation / maximum stress) shall be higher than the value of the fracture elongation (%) of the first metal layer 110 relative to the maximum stress (MPa) (fracture elongation / maximum stress), and also higher than the value of the fracture elongation (%) of the second metal layer 120 relative to the maximum stress (MPa) (fracture elongation / maximum stress). More specifically, the value of the fracture elongation (%) of the first metal layer 110 relative to the maximum stress (MPa) (fracture elongation / maximum stress) and the value of the fracture elongation (%) of the second metal layer 120 relative to the maximum stress (MPa) (fracture elongation / maximum stress) shall be, for example, less than 0.400 and, for example, 0.300 or less.When the electromagnetic shielding material comprises three or more metal layers, the two metal layers closest to each outermost layer of the electromagnetic shielding material (i.e., the layer located on the outer surface of the electromagnetic shielding material) correspond to the first metal layer 110 and the second metal layer 120, and the layer provided between the first metal layer 110 and the second metal layer 120 may be the stress relaxation layer 150 (see Figure 1). As shown in Figure 1, the first metal layer 110 and the second metal layer 120 may be located on the outermost layer, and as shown in Figure 2, resin layers 230 and 240 may be provided on the outer surface side of the first metal layer 110 and the second metal layer 120. Here, the maximum stress and elongation at break are measured using a tensile testing device. The measurement procedure is as follows. A SHIMAZU AUTOGRAPH AGS-X-5kN or an equivalent device is used to measure the maximum stress and elongation at break. Two test specimens are prepared by cutting the stress relaxation layer into strips 160 mm long and 12.7 mm wide. If the stress relaxation layer includes a metal layer made of rolled metal, one test specimen is prepared with the longitudinal direction oriented in the rolling direction of the metal layer, and one test specimen with the width direction oriented in the rolling direction of the metal layer. The top and bottom 30 mm of the test specimens are used as the chuck portion of the apparatus, and a tensile test is performed on each of the two prepared test specimens with a chuck distance of 100 mm and a tensile speed of 50 mm / min. The elongation (%) up to the point where at least one layer of the test specimen breaks and the maximum tensile stress (MPa) up to the break are measured. The average elongation up to the break is defined as the break elongation (%), and the average of the maximum tensile stresses is defined as the maximum stress (MPa). Note that, if the stress relaxation layer includes a resin layer and a metal layer, the measurement of the maximum stress and break elongation is considered to have ended when either the resin layer or the metal layer breaks, or when both the resin layer and the metal layer break simultaneously. Furthermore, when peeling the stress relaxation layer from the surface of the metal layer of an electromagnetic shielding material and measuring the maximum stress and fracture elongation of the stress relaxation layer, for example, the stress relaxation layer can be fixed to the stage of the apparatus with a fixing device, and the metal layer can be grasped by a gripper located higher than the stage and moved vertically upward at a tensile speed of 300 mm / min or more (stroke), thereby peeling the metal layer from the electromagnetic shielding material and extracting the stress relaxation layer. In this case, the apparatus may be, for example, an IMADA MX2-5000N or an equivalent thereto.

[0014] (Maximum Stress) From the viewpoint of improving moldability, the maximum stress (MPa) of the stress relaxation layer 150 is not particularly limited, but it is preferably 30.0 MPa or more and 200.0 MPa or less, and more preferably 48.8 MPa or more and 194.1 MPa or less. However, if it is less than 30.0 MPa, the sample may not be able to withstand the holding pressure during molding and may break immediately. Also, if it exceeds 200.0 MPa, the force applied to the interface between each layer during molding becomes large and moldability may decrease.

[0015] (Elongation at Break) From the viewpoint of improving moldability, the elongation at break (%) of the stress relaxation layer 150 is not particularly limited, but is preferably within a predetermined range. That is, the elongation at break is preferably 90.0% or more at the lower limit, and more preferably 104.7% or more. Furthermore, the elongation at break is preferably 200.0% or less at the upper limit, and more preferably 182.4% or less. However, if it is less than 90.0%, it may not be able to follow the deformation during molding, and the moldability may not be good.

[0016] The stress-relieving layer 150 may comprise at least two resin layers and at least one metal layer, from the viewpoint of ensuring excellent moldability. In this case, it is preferable that at least one metal layer of the stress-relieving layer 150 is sandwiched between at least two resin layers. In the stress-relieving layer 150 shown in Figures 1 and 2, the metal layer 170 is sandwiched between the resin layers 160 and 180. In this case, the electromagnetic wave shielding material 100 shown in Figure 1 has a structure in which at least one layer each of resin layers 160 and 180 and metal layers 110 and 170 are alternately laminated, and the electromagnetic wave shielding material 200 shown in Figure 2 has a structure in which at least one layer each of resin layers 160, 180, 230, and 240 and metal layers 110, 170, and 120 are alternately laminated. Electromagnetic wave shielding materials 100 and 200 having such structures have an electromagnetic wave shielding effect and heat dissipation properties, and can therefore be used as heat dissipation members. Furthermore, since the electromagnetic shielding materials 100 and 200 are constructed by alternately laminating at least one resin layer 160, 180, 230, 240 and a metal layer 110, 170, 120, the weight of the electromagnetic shielding materials 100 and 200 can be reduced compared to a single-layer metal layer of the same thickness.

[0017] Here are some examples of the configuration of the stress relaxation layer: (1) When the stress relaxation layer is composed of two layers, examples include metal layer / resin layer, metal layer / metal layer, and resin layer / resin layer. (2) When the stress relaxation layer is composed of three layers, examples include metal layer / resin layer / metal layer, resin layer / metal layer / resin layer (see Figures 1 and 2), resin layer / metal layer / metal layer, metal layer / resin layer / resin layer, metal layer / metal layer / metal layer, and resin layer / resin layer / resin layer (see Figure 3). (3) When the stress relaxation layer is composed of four layers, in addition to metal layer / resin layer / metal layer / resin layer, examples include metal layer / metal layer / metal layer / resin layer, metal layer / metal layer / resin layer / metal layer, metal layer / metal layer / metal layer / metal layer, and resin layer / resin layer / resin layer. (4) The stress relief layer is composed of three layers: resin layer / metal layer / resin layer / metal layer / resin layer, metal layer / resin layer / metal layer / resin 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 / 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 / resin layer / metal layer / resin layer, metal layer / resin layer / metal layer / resin layer, metal layer / resin layer / metal layer / resin layer The following are examples of layers / resin layer / metal layer, metal layer / resin layer / metal layer / resin layer / resin layer, metal layer / resin layer / resin layer / metal layer / resin layer, metal layer / resin layer / resin layer / resin layer / metal layer, metal layer / resin layer / resin layer / resin layer / resin layer, resin layer / metal layer / metal layer / metal layer / resin layer, resin layer / resin layer / metal layer / resin layer / resin layer, resin layer / resin layer / metal layer / resin layer / resin layer, metal layer / resin layer / metal layer / metal layer / resin layer, and resin layer / resin layer / resin layer / resin layer.

[0018] (Thickness of stress relaxation layer) The thickness of the stress relaxation layer 150 is, for example, 50 μm or more at the lower limit and 60 μm or more at the upper limit. On the other hand, the thickness of the stress relaxation layer 150 is, for example, 500 μm or less and 450 μm or less at the upper limit. Within the above range, moldability can be improved more reliably. The thickness of the stress relaxation layer 150 can be measured in the same way as the thickness of the electromagnetic shielding materials 100 and 200. If the thickness of the stress relaxation layer 150 in the electromagnetic shielding materials 100 and 200 is to be measured, the thickness can be measured by observing the cross-section with an SEM or similar device.

[0019] <Metal Layers> (Shape) The shape of the metal layers 110, 120, and 170 is not particularly limited, but they may be foil-like, for example. That is, the metal layers 110, 120, and 170 may be metal foils.

[0020] (Metallic Material) There are no particular restrictions on the metallic material constituting the metal layers 110, 120, and 170, but it is preferable that it contains one or more combinations of copper, copper alloys, aluminum, aluminum alloys, iron, iron alloys, nickel, and nickel 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. The metal layers 110, 120, and 170 may be made of copper foil. When copper foil is used as the metal layers 110, 120, and 170, 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 the copper foil, but rolled copper foil, which has excellent formability, is preferred. When alloying elements are added to the copper foil to make a 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 one or more combinations of tin, manganese, chromium, zinc, zirconium, magnesium, nickel, silicon, and silver in a total of 50 to 2000 ppm by mass, and / or phosphorus in a total of 10 to 50 ppm by mass, as this improves elongation compared to pure copper foil of the same thickness. 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.

[0021] (Thickness) The thickness of each metal layer 110, 120, and 170 is, for example, 5 μm or more at the lower limit and 10 μm or more at the upper limit. On the other hand, the thickness of each metal layer is, for example, 70 μm or less and 50 μm or less at the upper limit. The thickness of the metal layers 110, 120, and 170 can be measured using the same method as the thickness of the electromagnetic shielding materials 100 and 200. If the thickness of the metal layers 110, 120, and 170 in the electromagnetic shielding materials 100 and 200 is to be measured by observing the thickness cross-section with an SEM or similar device.

[0022] (Heat Treatment) The metal layers 110, 120, and 170 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, 120, and 170 may be laminated onto the resin layers 160, 180, 230, and 240 after heat treatment.

[0023] (Surface Treatment Film) From the viewpoint of stably improving moldability and adhesion with the resin layers 160, 180, 230, and 240, although not shown in the figures, at least one surface of the metal layers 110, 120, and 170 (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.

[0024] The surface treatment film can be composed of, for example, a heat-resistant treatment film and / or a chromate treatment film.

[0025] 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 element (in any form such as metal, alloy, oxide, nitride, or sulfide) or a combination of two or more elements from the following: 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.

[0026] 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.

[0027] 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

[0028] 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.

[0029] 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-

[0030] <Resin Layer> The resin layers 160, 180, 230, and 240 are not particularly limited in shape, but for example, they can be in the form of a film. If the resin layers 160, 180, 230, and 240 are in the form of a film, the film is not particularly limited, but examples include unoriented films, uniaxially oriented films, and biaxially oriented films.

[0031] (Resin Material) The resin layers 160, 180, 230, and 240 are not particularly limited in terms of resin material, but it is preferable that they contain one or more combinations of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polypropylene (PP), nylon (PA66), polyphenylene sulfide (PPS), and urethane. Furthermore, from the viewpoint of heat dissipation, metal powders such as copper and aluminum, fillers, and inorganic powders such as carbon and graphite may be included in the resin layers 160, 180, 230, and 240. The content of inorganic powder in the resin layers 160, 180, 230, and 240 is not particularly limited, but is, for example, 95% by volume or less.

[0032] (Thickness of the resin layer) The thickness of each layer of the above resin layers 160, 180, 230, and 240 is, for example, 10 μm or more at the lower limit and 20 μm or more at the upper limit. On the other hand, the thickness of each layer is, for example, 250 μm or less and 200 μm or less at the upper limit. The thickness of the resin layers 160, 180, 230, and 240 can be measured using the same method as the thickness of the electromagnetic wave shielding materials 100 and 200.

[0033] When forming multiple resin layers, all resin layers may be made of the same material, or different materials may be used for each layer. Furthermore, all resin layers may have the same thickness, or different thicknesses may be used for each layer.

[0034] (Lamination Method) As a means of laminating the resin layers 160, 180, 230, 240 and the metal layers 110, 120, 170, an adhesive may be used between the resin layers 160, 180, 230, 240 and the metal layers 110, 120, 170, or the resin layers 160, 180, 230, 240 may be heat-pressed to the metal layers 110, 120, 170 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 resin, epoxy resin, urethane, polyester, polycarbonate, silicone resin, vinyl acetate, styrene-butadiene rubber, nitrile rubber, phenolic resin, cyanoacrylate, etc. For ease of manufacture and cost reasons, urethane-based, polyester-based, and vinyl acetate-based adhesives are preferred. From the viewpoint of heat dissipation, thermally conductive inorganic powders such as alumina, metal powders, powders such as carbon and graphite, and fillers may be included in the adhesive. The content of inorganic powder in the adhesive is not particularly limited, but for example, it is 95% by mass or less.

[0035] (Other Embodiments) The electromagnetic wave shielding material 300 shown in Figure 3 comprises, in order: one outermost resin layer 230, a first metal layer 110, a stress relaxation layer 350 on the surface 111 of the first metal layer 110, a second metal layer 120 on the surface 351 of the stress relaxation layer 350 opposite to the first metal layer 110, and the other outermost resin layer 240. The stress relaxation layer 350 is made of resin layers and comprises, in order: a first resin layer 360, a second resin layer 370, and a third resin layer 380. Preferably, the first resin layer 360, the second resin layer 370, and the third resin layer 380 are the resin materials described above. In particular, the resin material of the third resin layer 380 is more preferably the same as the resin material of the first resin layer 360, from the viewpoint of more reliably improving moldability, and it is especially preferable that the first resin layer 360 and the third resin layer 380 are made of polyethylene terephthalate. The stress relaxation layer 350 of the electromagnetic wave shielding material 300 shown in Figure 3 consists of multiple resin layers (first resin layer 360, second resin layer 370, third resin layer 380), but it may also be a single resin layer.

[0036] Although not shown in the figures, the stress relaxation layer of the electromagnetic wave shielding material may be composed of a metal layer, unlike the configuration of the stress relaxation layers 150 and 350 shown in Figures 1 to 3.

[0037] (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.

[0038] 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.

[0039] [Fabrication of Electromagnetic Shielding Materials] In Examples 1 to 10 and Comparative Examples 1 to 6, the materials shown in Table 1 were prepared, and electromagnetic shielding materials were fabricated according to the configuration shown in Table 2. In addition, rolled copper foil was used for metal layer A shown in Table 1. The rolled copper foil was heat-treated at 300°C for 1 hour under a nitrogen atmosphere. Also, PEN in Table 1 is an abbreviation for polyethylene naphthalate. The specific fabrication method will be described below. The thickness of each material shown in Table 1 was measured according to the method described above. The results are shown in Table 1.

[0040] In the preparation of the electromagnetic shielding materials of Examples 1 to 10 and Comparative Examples 1 to 6, a resin layer and a metal layer were laminated using a two-component mixed adhesive (main component: SD2, curing agent: H-5) manufactured by Rock Paint Co., Ltd., according to the configuration shown in Table 2. In these electromagnetic shielding materials, the layer provided between each metal layer located closest to each outermost layer was designated as a stress relaxation layer. Furthermore, the stress relaxation layers of Examples 1 to 10 and Comparative Examples 1 to 6 were prepared in the same manner as the preparation of the electromagnetic shielding materials, according to Table 2.

[0041] The electromagnetic shielding materials and stress relaxation layers of Examples 1 to 10 and Comparative Examples 1 to 6, which were prepared as described above, were evaluated for their characteristics as follows.

[0042] <Maximum Stress and Elongation at Break> The maximum stress and elongation at break were measured for the stress relaxation layers of Examples 1 to 10 and Comparative Examples 1 to 6. The measurement method followed the method described above. In addition, for Examples 1 to 10 and Comparative Examples 1 to 6, the ratio of the elongation at break of the stress relaxation layer to the maximum stress of the stress relaxation layer was calculated based on the obtained maximum stress and elongation at break.

[0043] <FLD fracture stroke>The mold was reduced to 25% of the size described in ISO-12004-2-2008, the size of the punch was 22.5 mm, the radius of curvature R of the punch was 6 mm, and the radius of curvature R of the die was 2 mm. In addition, a W-shaped notch was provided to suppress wrinkles during the forming test, and the holding pressure of the mold was 4000 N. The test piece was circular with a diameter of φ60 mm, set in the above mold, and formed by punch extrusion. The extrusion depth until at least one layer of the test piece was broken was measured. This test was conducted 5 times, and the average value of the measured extrusion depth was taken as the fracture stroke. At this time, when the fracture stroke was 16.5 mm or more, it was judged that the formability was good. On the other hand, when the fracture stroke was less than 16.5 mm, it was judged that the formability was not good.

[0044] Based on the above results, the relationship between the elongation at break / stress relaxation layer maximum stress and the fracture stroke of the stress relaxation layer in Examples 1 to 10 and Comparative Examples 1 to 6 is shown in FIG. 4.

[0045]

[0046]

[0047] As can be seen from the above results, according to the embodiment of the present invention, an electromagnetic shielding material with good formability can be provided.

[0048] (Possibility of contribution to SDGs) According to the above embodiment, since an electromagnetic shielding material with excellent formability can be provided, there is a possibility of improving the product yield in the manufacture of electronic devices and the like. An improvement in product yield leads to a stable supply of products and a reduction in the loss of metal raw materials, which are limited resources. Therefore, the above embodiment may contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation," and Goal 12, "Ensure sustainable consumption and production patterns."

[0049] 100, 200, 300 Electromagnetic wave shielding material 110 First metal layer (metal layer) 111, 121, 112, 151, 351 Surface 120 Second metal layer (metal layer) 150, 350 Stress relaxation layer 160, 180, 230, 240 Resin layer 170 Metal layer 360 First resin layer (resin layer) 370 Second resin layer (resin layer) 380 Third resin layer (resin layer)

Claims

1. An electromagnetic wave shielding material comprising a first metal layer, a second metal layer, and a stress-relieving layer provided between the first metal layer and the second metal layer, wherein the stress-relieving layer includes a metal layer and / or a resin layer, and the value of the elongation at break (%) of the stress-relieving layer relative to the maximum stress (MPa) is 0.600 or more.

2. The electromagnetic wave shielding material according to claim 1, wherein the value of the elongation at break (%) relative to the maximum stress (MPa) of the stress relaxation layer is 0.650 or more and 3.000 or less.

3. The electromagnetic wave shielding material according to claim 2, wherein the value of the elongation at break (%) with respect to the maximum stress (MPa) of the stress relaxation layer is 0.704 or more and 2.629 or less.

4. The electromagnetic wave shielding material according to any one of claims 1 to 3, wherein the stress relaxation layer includes a resin layer, and the resin layer of the stress relaxation layer includes one or more of the following: polyethylene terephthalate, polybutylene terephthalate, polypropylene, nylon, polyphenylene sulfide, and urethane.

5. The electromagnetic wave shielding material according to claim 1, wherein the stress relaxation layer is made of a resin layer.

6. The electromagnetic wave shielding material according to claim 5, wherein the resin layer of the stress relaxation layer comprises a first resin layer, a second resin layer, and a third resin layer in this order.

7. The electromagnetic wave shielding material according to claim 6, wherein the resin material of the third resin layer is the same as the resin material of the first resin layer.

8. The electromagnetic wave shielding material according to claim 7, wherein the first resin layer and the third resin layer are made of polyethylene terephthalate.

9. The electromagnetic wave shielding material according to any one of claims 1 to 4, wherein the stress relaxation layer comprises a resin layer and a metal layer.

10. The electromagnetic shielding material according to claim 9, wherein the stress-relieving layer comprises at least two resin layers and at least one metal layer, and the at least one metal layer is sandwiched between the at least two resin layers.

11. The electromagnetic wave shielding material according to claim 10, wherein the at least one metal layer contains one or more of the following: copper, copper alloy, aluminum, aluminum alloy, iron, iron alloy, nickel, and nickel alloy.

12. An electromagnetic wave shielding material according to any one of claims 1 to 11, wherein the surface of the first metal layer opposite to the stress relaxation layer has a resin layer arranged as the outermost layer.

13. The electromagnetic wave shielding material according to any one of claims 1 to 12, wherein the elongation at break of the stress relaxation layer is 90.0% or more and 200.0% or less.

14. The electromagnetic wave shielding material according to claim 13, wherein the elongation at break of the stress relaxation layer is 104.7% or more and 182.4% or less.

15. The electromagnetic wave shielding material according to any one of claims 1 to 14, wherein the maximum stress of the stress relaxation layer is 30.0 MPa or more and 200.0 MPa or less.

16. The electromagnetic wave shielding material according to claim 15, wherein the maximum stress of the stress relaxation layer is 48.8 MPa or more and 194.1 MPa or less.

17. The electromagnetic wave shielding material according to any one of claims 1 to 16, wherein the thickness of the stress relaxation layer is 50 μm or more and 500 μm or less.

18. A covering or exterior material for electrical and electronic equipment, comprising the electromagnetic wave shielding material described in any one of claims 1 to 17.

19. An electrical or electronic device comprising the covering material or exterior material described in claim 18.

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