Electromagnetic wave shielding material, electronic component, and electronic device

Abstract

Provided is an electromagnetic wave shielding material in which a resin-containing layer is present in at least one outermost layer portion, and which has one or two laminated structures satisfying the following (1) to (4). (1) A metal foil-containing layer, in which the surface of the metal foil is exposed on the outermost surface, surrounds the periphery of at least a portion of the side surface of the resin-containing layer. (2) The resin-containing layer and a metal layer are adjacent to each other directly or with another layer disposed therebetween. (3) At least a portion of the outer peripheral region of the surface of the metal layer on the resin-containing layer side is a region on which the resin-containing layer is not present, and the region is electrically connected to the metal foil-containing layer. (4) The protruding height of the metal foil-containing layer in the thickness direction of the electromagnetic wave shielding material is 0-30 μm, with the position of the outermost surface of the resin-containing layer being defined as 0 μm.

Description

Electromagnetic shielding materials, electronic components, and electronic equipment

[0001] This invention relates to electromagnetic shielding materials, electronic components, and electronic devices.

[0002] In recent years, electromagnetic shielding materials have attracted attention as materials for reducing the effects of electromagnetic waves in various electronic components and electronic devices (see, for example, Patent Document 1).

[0003] WO2024 / 252893A1

[0004] Electromagnetic shielding materials can exhibit electromagnetic shielding performance (hereinafter also referred to as "electromagnetic shielding ability" or "shielding ability") by reflecting electromagnetic waves incident on the electromagnetic shielding material and / or attenuating them within the electromagnetic shielding material. It is desirable for electromagnetic shielding materials to exhibit superior shielding ability, as this contributes to further reducing the effects of electromagnetic waves on various electronic components and electronic devices.

[0005] In view of the above, one aspect of the present invention aims to provide an electromagnetic shielding material that can exhibit excellent electromagnetic shielding capabilities.

[0006] One aspect of the present invention is as follows: [1] An electromagnetic wave shielding material having one or two laminated structures that satisfy the following (1) to (4): (1) A metal foil-containing layer, on which the surface of the metal foil is exposed on the outermost surface, surrounds at least a portion of the side surface of the resin-containing layer; (2) The resin-containing layer and the metal layer are adjacent to each other directly or via other layers; (3) At least a portion of the outer peripheral region of the surface of the metal layer on the side of the resin-containing layer is a region on which the resin-containing layer is not present, and the region is electrically connected to the metal foil-containing layer; (4) The protruding height of the metal foil-containing layer in the thickness direction of the electromagnetic wave shielding material is 0 μm or more and 30 μm or less, with the outermost surface of the resin-containing layer being 0 μm; [2] The electromagnetic wave shielding material according to [1], having two of the above laminated structures. [3] The electromagnetic wave shielding material according to [2], further comprising a magnetic layer between the metal layer of one of the two laminated structures and the metal layer of the other laminated structure. [4] The electromagnetic wave shielding material according to [3], wherein the magnetic layer is a layer containing magnetic particles and resin. [5] The electromagnetic wave shielding material according to any one of [1] to [4], wherein the protruding height of the metal foil-containing layer in (4) is 1 μm or more and 30 μm or less. [6] The electromagnetic wave shielding material according to any one of [1] to [5], wherein the protruding height of the metal foil-containing layer in (4) is 10 μm or more and 20 μm or less. [7] The electromagnetic wave shielding material according to any one of [1] to [6], comprising two of the above laminated structures, further comprising a magnetic layer between the metal layer of one of the two laminated structures and the metal layer of the other laminated structure, wherein the magnetic layer is a layer containing magnetic particles and resin, and the protruding height of the metal foil-containing layer in (4) is 1 μm or more and 30 μm or less. [8] The electromagnetic shielding material according to [7], wherein the protruding height of the metal foil-containing layer in (4) above is 10 μm or more and 20 μm or less. [9] An electronic component comprising the electromagnetic shielding material according to any one of [1] to [8].

[10] An electronic device comprising the electromagnetic shielding material according to any one of [1] to [8].

[0007] According to one aspect of the present invention, an electromagnetic shielding material capable of exhibiting excellent electromagnetic shielding performance can be provided. Furthermore, according to another aspect of the present invention, an electronic component and electronic device containing this electromagnetic shielding material can be provided.

[0008] This is a cross-sectional view of the electromagnetic shielding material of Example 1. This is a plan view of the electromagnetic shielding material of Example 1. This shows a plan view of the electromagnetic shielding material of Example 1 after the outermost resin layer and the outer edge of the adhesive layer directly beneath it have been removed during the manufacturing process. This shows cross-sectional views of the shielding performance measurement samples (electromagnetic shielding materials) of Examples 1 to 3. This shows cross-sectional views of the shielding performance measurement samples (electromagnetic shielding materials) of Comparative Examples 1 to 3. This shows cross-sectional views of the shielding performance measurement samples (electromagnetic shielding materials) of Comparative Examples 4 and 5. This shows a cross-sectional view of the KEC method evaluation apparatus. This shows a plan view of the KEC method evaluation apparatus. This shows a measurement explanatory diagram of the KEC method evaluation apparatus.

[0009] [Electromagnetic wave shielding material] One aspect of the present invention relates to an electromagnetic wave shielding material having one or two laminated structures in which a resin-containing layer is present in at least one of the outermost layers and satisfies the following conditions (1) to (4).

[0010] (1) A metal foil-containing layer, with the metal foil surface exposed on its outermost surface, surrounds at least a portion of the side surface of the resin-containing layer. (2) The resin-containing layer and the metal layer are adjacent to each other, either directly or via another layer. (3) At least a portion of the outer peripheral region of the surface of the metal layer on the side facing the resin-containing layer is a region on which the resin-containing layer does not exist, and this region is electrically connected to the metal foil-containing layer. (4) The protruding height of the metal foil-containing layer in the thickness direction of the electromagnetic wave shielding material is between 0 μm and 30 μm, with the outermost surface of the resin-containing layer being 0 μm.

[0011] In the present invention and this specification, "electromagnetic wave shielding material" means a material that can exhibit shielding ability against electromagnetic waves of at least one frequency or at least a portion of a frequency band. "Electromagnetic waves" include magnetic field waves and electric field waves. The "electromagnetic wave shielding material" can exhibit shielding ability against one or both of magnetic field waves of at least one frequency or at least a portion of a frequency band and electric field waves of at least one frequency or at least a portion of a frequency band.

[0012] In the present invention and this specification, "metal foil" refers to a metal film with a thickness of 200 μm or less, which, unlike metal mesh and perforated metal, has no through holes in most of its surface. "Having no through holes in most of its surface" means that, with the surface area of ​​the metal foil being 100%, 90% to 100% of the area is a continuous portion without through holes. The metal foil may have mounting screw holes, wiring through holes, or notches in some parts. The purity of the metal in the metal foil, i.e., the metal content in the metal foil, is 99.0% by mass or more and 100.0% by mass or less, relative to the total mass of the metal foil, and may be 99.5% by mass or more and 100.0% by mass or 99.8% by mass or more and 100.0% by mass or less. The metal content in the metal foil refers to the content on a mass basis.

[0013] In the present invention and this specification, "magnetic" means ferromagnetic property.

[0014] In the present invention and this specification, various thicknesses are determined by imaging a cross-section of an electromagnetic shielding material exposed by a known method using a scanning electron microscope (SEM), and taking the arithmetic mean of five randomly selected thicknesses in the resulting SEM image.

[0015] In recent years, electromagnetic shielding materials having a laminated structure including a metal layer have been proposed (see, for example, Patent Document 1 (WO2024 / 252893A1)). Furthermore, Patent Document 1 (WO2024 / 252893A1) discloses an electromagnetic shielding material in which the outermost layer is a resin-containing layer (details will be described later). The present inventors have conducted extensive research on electromagnetic shielding materials having a laminated structure including a metal layer and in which the outermost layer is a resin-containing layer, and have newly discovered that the shielding performance of the electromagnetic shielding material can be improved by providing a configuration that satisfies the above (1) to (4). The present inventors speculate on this point as follows: In electronic components or electronic devices incorporating electromagnetic shielding materials, the outermost surface of the electromagnetic shielding material is usually in contact with a metal member such as a metal plate. In electromagnetic shielding materials in which only a resin-containing layer exists in the outermost layer, the metal member cannot make electrical contact with the metal layer of the electromagnetic shielding material. In contrast, by satisfying conditions (1) to (3) above, the metal layer of the electromagnetic wave shielding material can establish electrical conductivity with the metal component via the metal foil-containing layer. Furthermore, as a result of the inventors' diligent research, it has been newly discovered that satisfying condition (4) above by ensuring a height difference between the metal foil-containing layer and the resin-containing layer at the outermost surface of the electromagnetic wave shielding material also contributes to improving the shielding performance. The inventors speculate that this is because a larger height difference results in a larger space formed by the height difference, and the resonance and / or amplification of electromagnetic waves in that space hinders the improvement of the shielding performance. However, the present invention is not limited to the speculation described herein.

[0016] The electromagnetic shielding material described above will be explained in more detail below.

[0017] <Specific Examples of Layer Configurations for Electromagnetic Shielding Materials> Figure 1 is a cross-sectional view of the electromagnetic shielding material of Example 1, which will be described later. Figure 2 is a plan view of the electromagnetic shielding material of Example 1. Note that Figures 1 and 2 and the drawings described later are schematic diagrams, and the thickness ratios of the various layers shown in the figures differ from the actual thickness ratios. Also, the forms shown in the various drawings are illustrative, and the present invention is not limited to the illustrated forms.

[0018] The electromagnetic shielding material of Example 1 has a resin layer 1 adjacent to a metal layer 3 via an adhesive layer 2 at its outermost surface, and a metal foil-containing layer 5 surrounding the entire circumference of the side surface of the resin layer 1. As shown in Figure 2, in the electromagnetic shielding material of Example 1, the entire circumference of the side surface of the resin layer 1 is surrounded by the metal foil-containing layer 5. Figure 2 shows the metal foil 50 of the outermost layer of the metal foil-containing layer 5. However, the form shown in Figure 2 is illustrative, and in an electromagnetic shielding material according to one aspect of the present invention, it is sufficient that at least a part of the side surface of the resin-containing layer at the outermost surface is surrounded by the metal foil-containing layer. This is because if the metal foil-containing layer is present in at least a part of the outermost surface of the electromagnetic shielding material, electrical conductivity can be established between the metal member and the metal layer of the electromagnetic shielding material when a metal member comes into contact with the outermost surface of the electromagnetic shielding material. For similar reasons, the size (e.g., width) of the metal foil-containing layer is not particularly limited.

[0019] In an electromagnetic shielding material according to one aspect of the present invention, the resin-containing layer and the metal foil-containing layer may be in contact or separated at the outermost layer. In the electromagnetic shielding material of Example 1, the resin layer 1 and the metal foil-containing layer 5 are separated at the outermost layer. Therefore, the plan view shown in Figure 2 illustrates the metal layer 3 located in the portion where the resin layer 1 and the metal foil-containing layer 5 are separated.

[0020] The metal foil-containing layer 5 of the electromagnetic wave shielding material in Example 1 is a laminated film in which two layers, a metal foil 50 and a conductive adhesive layer 51, are laminated. In the present invention and this specification, "conductive" means that the resistivity ρ is 1 Ω·m or less. The resistivity ρ of the conductive layer is 1 Ω·m or less, for example it can be 0.1 Ω·m or less, preferably 0.01 Ω·m or less, and more preferably 0.001 Ω·m or less. The resistivity ρ of the conductive layer can be, for example, 0.0001 Ω·m or more, but may be less than 0.0001 Ω·m. The resistivity ρ is determined by measuring the resistance value R (unit: Ω) of the object to be measured and the cross-sectional area S (unit: m) of the object to be measured. ２The resistivity R is calculated from the voltage and the distance L [m] between electrodes using the following formula. The resistivity R can be measured using a commercially available digital multimeter or other known measuring device capable of measuring resistance. Resistivity ρ (unit: Ω・m) = RS / L

[0021] In the present invention and this specification, the "metal foil-containing layer" can be a laminate of one or more layers of metal foil and conductive layers in one embodiment, or a single layer of metal foil alone in another embodiment. Such a metal foil-containing layer having conductivity with a metal layer located below the resin-containing layer at the outermost surface of the electromagnetic shielding material can contribute to improving the shielding performance of the electromagnetic shielding material. Specifically, in an electromagnetic shielding material according to one embodiment of the present invention, at least a portion of the outer peripheral region of the surface of a metal layer adjacent to the resin-containing layer at the outermost surface, directly or via another layer, is a region where the resin-containing layer is not present, and this region has conductivity with the metal foil-containing layer at the outermost surface. In the present invention and this specification, "conductivity" means a connection that allows current to flow. For example, a state in which the conductive layer of the laminate and the region of the metal layer are in direct contact, and a state in which the metal foil and the region of the metal layer are in direct contact, are states of conductivity. Direct contact can also be described as "adjacent."

[0022] The above explains how to satisfy the conditions (1) to (3) described earlier. Furthermore, an electromagnetic shielding material according to one aspect of the present invention satisfies the following condition (4).

[0023] (4) The protruding height of the metal foil-containing layer in the thickness direction of the electromagnetic wave shielding material is 0 μm or more and 30 μm or less, with the outermost surface of the resin-containing layer being 0 μm.

[0024] The protrusion height in (4) above can also be expressed as the difference between the thickness of the metal foil-containing layer and the thickness of the layer located on the surface of the metal layer (or the total thickness of the layers if there are multiple layers). For example, in the electromagnetic shielding material of Example 1, the outermost resin layer 1 and the adhesive layer 2 located directly beneath it are layers located on the surface of the metal layer 3. Therefore, in the electromagnetic shielding material of Example 1, the protrusion height in (4) above can be calculated as "(thickness of the metal foil-containing layer) - (thickness of the outermost resin layer 1 + thickness of the adhesive layer 2 located directly beneath it)".

[0025] In the electromagnetic shielding material described above, the protrusion height of (4) is 0 μm or more and 30 μm or less. The protrusion height of (4) is 0 μm or more, and can also be 1 μm or more, 2 μm or more, 4 μm or more, 6 μm or more, 8 μm or more, or 10 μm or more, in order to allow the metal member to come into contact with the metal foil of the metal foil-containing layer when the metal member comes into contact with the outermost surface of the electromagnetic shielding material. From the viewpoint of improving shielding performance, the protrusion height of (4) is 30 μm or less, preferably 28 μm or less, and more preferably in the order of 26 μm or less, 24 μm or less, 22 μm or less, 20 μm or less, 18 μm or less, and 16 μm or less.

[0026] The electromagnetic shielding material of Example 1 has the following layer configuration. In the following, the symbol " / " means that the layer to the left of this symbol and the layer to the right are in direct contact (i.e., adjacent) without any other layers in between. One outermost layer resin layer / adhesive layer / metal layer / adhesive layer / resin layer / magnetic layer / resin layer / adhesive layer / metal layer / adhesive layer / the other outermost layer resin layer

[0027] In the above example of layer configuration, one or more adhesive layers can be replaced with tack layers. Details of the adhesive and tack layers will be described later. In one embodiment, a tack layer or adhesive layer can be positioned between the resin layer and the magnetic layer.

[0028] The layers present in the electromagnetic shielding material described above, and the layers it may have, will be explained in more detail below.

[0029] <Resin-containing layer> In the present invention and this specification, "resin-containing layer" means a layer containing one or more types of resin. In the electromagnetic shielding material described above, a resin-containing layer is present in at least one of the outermost layers. Therefore, the electromagnetic shielding material contains one or more resin-containing layers. When the electromagnetic shielding material contains two or more resin-containing layers, these resin-containing layers may be layers with the same composition and thickness, or they may be layers with different compositions and / or thicknesses.

[0030] The thickness of a single resin-containing layer in the electromagnetic shielding material can be, for example, 1 μm or more and 60 μm or less. However, it is not limited to the range exemplified herein.

[0031] In an electromagnetic shielding material, if the layer closer to the outermost surface of the electromagnetic shielding material is called the "upper layer" and the layer further away is called the "lower layer," then the resin-containing layer located in the outermost part of the electromagnetic shielding material can be in direct contact with the metal layer located on the lower side, or can be adjacent to it via one or more other layers. The other layers mentioned above include one or more layers selected from the group consisting of adhesive layers and bonding layers, which will be described later. For example, the resin-containing layer in the outermost part of the electromagnetic shielding material can be adjacent to the metal layer on the lower side via one adhesive or bonding layer.

[0032] The specific form of the resin-containing layer is described below.

[0033] (Adhesive Layer) An adhesive layer can be considered as one form of the resin-containing layer. In the present invention and this specification, "adhesive layer" means a layer that has tackiness on its surface at room temperature. With respect to tackiness, "room temperature" means 23°C. Such a layer adheres to an object by its adhesive force when it comes into contact with the object. Tackiness generally refers to the property of exhibiting adhesive force in a short time after contact with an object with very light force. In the present invention and this specification, "having tackiness" means that the result in the inclined ball tack test specified in JIS Z 0237:2009 (measurement environment: temperature 23°C, relative humidity 50%) is No. 1 to No. 32. If other layers are laminated on the surface of the adhesive layer, for example, the surface of the adhesive layer exposed by peeling off the other layers can be subjected to the above test. If other layers are laminated on one surface and the other surface of the adhesive layer, the other layers on either surface can be peeled off.

[0034] As the adhesive layer, a film can be made by coating an adhesive layer-forming composition containing an adhesive such as an acrylic adhesive, a rubber adhesive, a silicone adhesive, or a urethane adhesive. The adhesive layer-forming composition can be applied, for example, to a support. The application can be carried out using known application equipment such as a blade coater or a die coater. The application can be carried out in a so-called roll-to-roll manner or in a batch manner. Examples of support materials to which the adhesive layer-forming composition is applied include films of various resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and other polyesters, polycarbonate (PC), polymethyl methacrylate (PMMA) and other acrylics, cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. As the support material, a support material can be used in which the surface to which the adhesive layer-forming composition is applied (the surface to be coated) has been subjected to a release treatment by a known method. One form of release treatment is the formation of a release layer. Alternatively, commercially available release-treated resin films can be used as the support material. By using a support whose surface to be coated has been subjected to a release treatment, the adhesive layer and the support can be easily separated after film formation. The adhesive layer can be formed by coating the surface to be coated with an adhesive layer-forming composition in which the adhesive is dissolved and / or dispersed in a solvent and drying it. Alternatively, an adhesive tape containing an adhesive layer can be used. As an adhesive tape, for example, double-sided tape can be used. Double-sided tape has adhesive layers on both sides of the support. Alternatively, an adhesive tape with an adhesive layer on one side of the support can be used. Examples of supports include films, nonwoven fabrics, and paper made of various resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and other polyesters, polycarbonate (PC), polymethyl methacrylate (PMMA) and other acrylics, cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide.As adhesive tapes having an adhesive layer on one or both sides of the support, commercially available products can be used, and adhesive tapes manufactured by known methods can also be used.

[0035] The thickness of the adhesive layer is not particularly limited; the thickness of each layer can be, for example, 1 μm or more and 30 μm or less.

[0036] (Adhesive Layer) An adhesive layer can also be considered as one form of the resin-containing layer. In the present invention and this specification, "adhesive layer" refers to a layer in which a liquid or gel-like adhesive solidifies after contact with an adherend through a change in state such as drying and curing, and at that time exhibits adhesion to the adherend through an anchoring effect, physical interaction, or the formation of chemical bonds. In one form, the adhesive layer may be a layer that does not have tackiness on its surface at room temperature. In another form, the adhesive layer may be adjacent to a magnetic layer or a metal layer, and can firmly bond the magnetic layer or metal layer to the resin-containing layer. The adhesive contains a resin that solidifies after drying or curing. Examples of such resins include vinyl acetate resin, ethylene vinyl acetate resin, epoxy resin, cyanoacrylate resin, acrylic resin, polyurethane resin, chloroprene rubber, styrene butadiene rubber, etc. These resins may be liquid or gel-like in nature, or a solid resin may dissolve in a solvent to become liquid or gel-like. Examples of solvents included in adhesives include water, acetone, methyl ethyl ketone, cyclohexanone, and other ketone solvents; acetic acid ester solvents such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as cellosolve and butyl carbitol; aromatic hydrocarbon solvents such as toluene and xylene; amide solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; alcohol solvents such as ethanol, methanol, and propanol; and halogen solvents such as dichloromethane, trichloroethylene, and dichlorofluoroethane. Adhesives may also contain monomers that produce a resin through a chemical reaction after contact with the adherend. Examples of such monomers include epoxy monomers, isocyanates, polyols, polyphenols, acid anhydrides, acrylic acid esters, methacrylate esters, styrene monomers, and allyl monomers. Monomers contain one or more functional groups that undergo a chemical reaction. When monomers with three or more functional groups are used, a resin containing a three-dimensional molecular structure is produced after the chemical reaction, thereby forming an adhesive layer with higher mechanical strength.

[0037] The thickness of the adhesive layer is not particularly limited; the thickness of each layer can be, for example, 1 μm or more and 30 μm or less.

[0038] (Coating Layer) A coating layer can also be considered as one form of the resin-containing layer. In the present invention and this specification, a "coating layer" is a layer in which a liquid or gel-like coating agent solidifies after contact with an adherend through a change in state such as drying and curing, exhibiting water repellency, oil repellency, chemical resistance, abrasion resistance, etc., and contributing to suppressing aging deterioration of the electromagnetic wave shielding material, such as hydrolysis of the resin contained in the magnetic layer and / or resin-containing layer, and physical damage such as scratches. In one embodiment, the coating layer can be provided on the outermost layer of the electromagnetic wave shielding material. The coating agent contains a resin that solidifies after drying or curing. Examples of such resins include silicone resins, fluororesins, polyolefin resins, polyacetal resins, epoxy resins, acrylic resins, polyurethane resins, polyamide resins, polyimide resins, polyester resins, polyphenylene ether resins, polyphenylene sulfide resins, polyetherimide resins, and polycarbonate resins. These resins may be liquid or gel-like in nature. Alternatively, the solid resin may dissolve in the solvent to become liquid or gel-like. Examples of solvents included in the coating agent include water, ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone; acetic acid ester solvents such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as cellosolve and butyl carbitol; aromatic hydrocarbon solvents such as toluene and xylene; amide solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; alcohol solvents such as ethanol, methanol, and propanol; and halogen solvents such as dichloromethane, trichloroethylene, and dichlorofluoroethane.

[0039] The thickness of the coating layer is not particularly limited; the thickness of each layer can be, for example, 1 μm or more and 10 μm or less.

[0040] It is also possible to cover the end of the electromagnetic wave shielding material with a coating agent. This can suppress intrusion of moisture, oil content, and chemicals from the end, mechanical damage, and the like.

[0041] (Resin Layer) As one form of the resin-containing layer, a resin layer can be mentioned. In the present invention and the present specification, the "resin layer" is a resin film formed by molding a thermoplastic resin such as a synthetic resin into a film shape, wherein the resin film alone forms a film-like structure and has no tackiness at normal temperature. Examples of the thermoplastic resin contained in the resin film include polyethylene (PE) resin, polypropylene (PP) resin, polyvinyl chloride (PVC) resin, polystyrene (PS) resin, vinyl acetate resin, polyurethane resin, polyvinyl alcohol resin, ethylene vinyl acetate resin, styrene butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, olefin-based elastomer (PP), styrene-based elastomer, ABS (acrylonitrile-butadiene-styrene) resin, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polycarbonate (PC) resin, acrylic resins such as polymethyl methacrylate (PMMA), cyclic polyolefin, and various resins such as triacetyl cellulose (TAC).

[0042] The thickness of the resin layer per resin layer can be, for example, 10 µm or more, or 12 µm or more. Further, the thickness per resin layer is more preferably, for example, 250 µm or less, 200 µm or less, 150 µm or less, or 100 µm or less.

[0043] In one embodiment, the resin-containing layer located at the outermost layer can be a resin layer. Such a resin layer may be in direct contact with the metal layer on the lower layer side, or may be adjacent to the metal layer via one pressure-sensitive adhesive layer or adhesive layer, for example.

[0044] The resin layer can be bonded to the metal layer, for example, via an adhesive or bonding layer. Furthermore, because the resin layer is a thermoplastic resin-containing layer, it softens upon heating. When pressed against a substrate while heated, it flows and conforms to minute irregularities on the substrate's surface, exhibiting adhesive force through an anchoring effect. The bond is then maintained upon cooling. Therefore, in one embodiment, the resin layer can be bonded to the underlying metal layer without the need for an adhesive or bonding layer. Alternatively, commercially available or commercially produced double-sided tape can be used as the resin-containing layer laminate.

[0045] In a resin-containing laminate including a resin layer, the thickness of the resin layer relative to 100% of the laminate thickness can be, for example, 60% or more, 70% or more, or 80% or more, and can also be, for example, 100% or less, 99% or less, 98% or less, or 97% or less. The resin layer can be, for example, the resin film described above.

[0046] In one embodiment, the electromagnetic shielding material may have a resin-containing layer only on one or both of its outermost layers. In another embodiment, the electromagnetic shielding material may also have a resin-containing layer at one or more locations other than the outermost layer.

[0047] <Metal Foil Containing Layer> The metal foil contained in the metal foil containing layer that surrounds at least a portion of the side surface of the resin containing layer in the outermost layer may contain one or more metals, either as a pure metal consisting of a single metal element, as an alloy of two or more metal elements, or as an alloy of one or more metal elements and one or more nonmetal elements. For details on the metals contained in the metal foil, please refer to the description of the metals in the metal layer described below.

[0048] When the metal foil-containing layer is a laminate of metal foil and one or more other layers, the other layers may be one or more layers selected from the group consisting of conductive adhesive layers and conductive bonding layers. As described above, the adhesive layers and bonding layers can exhibit conductivity by containing conductive components.

[0049] The thickness of the metal foil-containing layer should be determined according to the thickness of the outermost resin-containing layer. For example, the thickness of the metal foil-containing layer (or the thickness of the laminate in the case of a laminate of metal foil and one or more other layers) can be 20 μm or more or 30 μm or more, and / or 200 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, or 60 μm or less. If the metal foil-containing layer is a single layer of metal foil, the thickness of that single layer of metal foil can be determined by referring to the description of the thickness of the metal foil-containing layer above. If the metal foil-containing layer is a laminate of metal foil and one or more other layers, the thickness of the metal foil can be, for example, 10 μm or more or 15 μm or more, and / or 100 μm or less, 50 μm or less, 40 μm or less, or 30 μm or less. The thickness of the other layers mentioned above (the thickness of the single layer if there is only one layer, or the total thickness if there are two or more layers) can be, for example, 10 μm or more or 20 μm or more, and / or 80 μm or less or 60 μm or less.

[0050] <Metal Layers> The electromagnetic shielding material has a metal layer adjacent to the resin-containing layer at the outermost layer, either directly or via another layer. If the electromagnetic shielding material has only one laminated structure satisfying (1) to (4) above, then the electromagnetic shielding material contains at least one metal layer. If the electromagnetic shielding material has two laminated structures satisfying (1) to (4) above, then the electromagnetic shielding material contains at least two metal layers. In one embodiment, the electromagnetic shielding material may have only the metal layer included in the laminated structure as a metal layer. In another embodiment, the electromagnetic shielding material may have one or more metal layers other than the metal layer included in the laminated structure as a metal layer. The total number of metal layers included in the electromagnetic shielding material may be, for example, one to three layers, or one to two layers. If the electromagnetic shielding material contains two or more metal layers, in one embodiment, these two or more metal layers may have the same composition and thickness, and in another embodiment, they may have different compositions and / or thicknesses. This also applies to the various layers included in the electromagnetic shielding material mentioned above.

[0051] In the present invention and this specification, "metal layer" means a layer containing a metal. The metal layer may be a layer containing one or more metals, such as a pure metal consisting of a single metal element, an alloy of two or more metal elements, or an alloy of one or more metal elements and one or more nonmetal elements.

[0052] The metal layer contained in the electromagnetic shielding material described above may be a layer containing one or more metals selected from the group consisting of various pure metals and various alloys. The metal layer can exert an attenuation effect in the electromagnetic shielding material. This is preferable from the viewpoint of improving the shielding performance of the electromagnetic shielding material. The attenuation effect is greater the larger the propagation constant, and the propagation constant is greater the higher the electrical conductivity, so it is preferable that the metal layer contains a metal element with high electrical conductivity. From this viewpoint, it is preferable that the metal layer contains a pure metal of Ag, Cu, Au, or Al, or an alloy containing any of these as the main component. A pure metal is a metal consisting of a single metal element and may contain trace amounts of impurities. Generally, a metal consisting of a single metal element with a purity of 99.0% or more is called a pure metal. Purity is measured by mass. An alloy is generally a pure metal with one or more metal or non-metal elements added to adjust its composition for purposes such as corrosion prevention and strength improvement. The main component in an alloy is the component with the highest proportion by mass, and can be, for example, a component that accounts for 80.0% by mass or more (for example, 99.8% by mass or less) in the alloy. From an economic standpoint, pure metals of Cu or Al, or alloys containing Cu or Al as the main component, are preferred.

[0053] The purity of the metal in the metal layer, i.e., the metal content in the metal layer, can be 99.0% by mass or more, 99.5% by mass or more, or 99.8% by mass or more, relative to the total mass of the metal layer. The metal content in the metal layer refers to the content on a mass basis. For example, a sheet of pure metal or alloy can be used as the metal layer. For example, a commercially available metal foil or a metal foil manufactured by a known method can be used as the metal layer. For pure metal Cu, sheets of various thicknesses (so-called copper foil) are commercially available. For example, such copper foil can be used as the metal layer. Copper foil includes electrolytic copper foil obtained by depositing copper foil on the cathode by electroplating, and rolled copper foil obtained by applying heat and pressure to an ingot and stretching it thinly. Either type of copper foil can be used as the metal layer of the electromagnetic shielding material described above. Also, for example, sheets of Al (so-called aluminum foil) of various thicknesses are commercially available. For example, such aluminum foil can be used as the metal layer.

[0054] From the viewpoint of reducing the weight of electromagnetic shielding materials, the metal layer is preferably a metal layer containing a metal selected from the group consisting of Al and Mg, and more preferably a layer containing a metal selected from the group consisting of Al and Mg as the main component. The main component of a metal layer is the component with the highest proportion by mass. In a layer containing a metal selected from the group consisting of Al and Mg as the main component, Al or Mg is the component with the highest proportion by mass in this layer. Such a layer may contain only Al or Mg from among Al and Mg, or it may contain Al and Mg. Both Al and Mg have a small value obtained by dividing specific gravity by electrical conductivity (specific gravity / electrical conductivity). The smaller this value of the metal used, the lighter the electromagnetic shielding material can be while exhibiting high shielding performance. As values ​​calculated from literature, for example, the values ​​obtained by dividing specific gravity by electrical conductivity (specific gravity / electrical conductivity) of Cu, Al, and Mg are as follows: Cu: 1.5 × 10 －７ m / S, Al: 7.6×10 －８ m / S, Mg: 7.6×10 －８m / S. From the above values, Al and Mg can be said to be preferred metals from the viewpoint of reducing the weight of the electromagnetic shielding material. A metal layer containing a metal selected from the group consisting of Al and Mg can contain only Al or Mg in one form, and can contain both in another form. From the viewpoint of reducing the weight of the electromagnetic shielding material, it is more preferable that the metal layer has a content of 80.0 mass% or more of a metal selected from the group consisting of Al and Mg, and even more preferable that the metal layer has a content of 90.0 mass% or more of a metal selected from the group consisting of Al and Mg. A metal layer containing at least Al among Al and Mg can have an Al content of 80.0 mass% or more, and can also have an Al content of 90.0 mass% or more. A metal layer containing at least Mg among Al and Mg can have an Mg content of 80.0 mass% or more, and can also have an Mg content of 90.0 mass% or more. The content of the metal selected from the group consisting of Al and Mg, the Al content, and the Mg content can each be, for example, 99.9% by mass or less. The content of the metal selected from the group consisting of Al and Mg, the Al content, and the Mg content are each percentages of the total mass of the metal layer.

[0055] From the viewpoint of economic efficiency, high electrical conductivity, and weight reduction of the electromagnetic wave shielding material, the metal layer is preferably a metal layer containing a metal selected from the group consisting of Al, Mg, and Cu, and more preferably a layer containing a metal selected from the group consisting of Al, Mg, and Cu as the main component. In a layer containing a metal selected from the group consisting of Al, Mg, and Cu as the main component, Al, Mg, or Cu is the component with the highest proportion by mass. Such a layer may contain only one, two, or three of the metals from Al, Mg, and Cu. From one or more of the above viewpoints, the metal layer is more preferably a metal layer with a metal content of 80.0% by mass or more of the metal selected from the group consisting of Al, Mg, and Cu, and even more preferably a metal layer with a metal content of 90.0% by mass or more of the metal selected from the group consisting of Al, Mg, and Cu. A metal layer containing at least Al from among Al, Mg, and Cu may have an Al content of 80.0% by mass or more, and may also have an Al content of 90.0% by mass or more. A metal layer containing at least Mg from among Al, Mg, and Cu may have an Mg content of 80.0% by mass or more, and may also have an Mg content of 90.0% by mass or more. A metal layer containing at least Cu from among Al, Mg, and Cu may have a Cu content of 80.0% by mass or more, and may also have a Cu content of 90.0% by mass or more. The content of the metal selected from the group consisting of Al, Mg, and Cu, the Al content, the Mg content, and the Cu content can each be, for example, 99.9% by mass or less. The content of the metal selected from the group consisting of Al, Mg, and Cu, the Al content, the Mg content, and the Cu content are each the content relative to the total mass of the metal layer.

[0056] Regarding the thickness of the metal layer, from the viewpoint of further improving the processability of the metal layer and the shielding performance of the electromagnetic wave shielding material, it is preferable that the thickness per layer be 4 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. On the other hand, from the viewpoint of the processability of the metal layer, it is preferable that the thickness per layer be 200 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less.

[0057] <Magnetic Layer> In one embodiment, the electromagnetic shielding material may include a magnetic layer on the lower side of the laminated structure that satisfies (1) to (4) described above. For example, if the electromagnetic shielding material has two laminated structures that satisfy (1) to (4) described above, a magnetic layer may be provided between the metal layer of one laminated structure and the metal layer of the other laminated structure. The presence of a magnetic layer sandwiched between two metal layers is preferable from the viewpoint of further improving the shielding ability of the electromagnetic shielding material.

[0058] In one embodiment, the magnetic layer can be a layer in direct contact with the metal layer. In another embodiment, the magnetic layer can be adjacent to the metal layer via one or more other layers. Such other layers include the resin-containing layers (single layer or laminate) described earlier. For resin-containing layers that may exist between the magnetic layer and the metal layer, refer to the previous description of resin-containing layers.

[0059] (Magnetic Material) The magnetic layer is a layer containing a magnetic material. Examples of magnetic materials include magnetic particles. As magnetic particles, one type selected from the group consisting of magnetic particles generally called soft magnetic particles, such as metal particles and ferrite particles, can be used, or two or more types can be used in any ratio. Since metal particles generally have a saturation magnetic flux density about 2 to 3 times that of ferrite particles, they can maintain relative permeability without magnetic saturation even under a strong magnetic field and exhibit shielding ability. Therefore, it is preferable that the magnetic particles contained in the magnetic layer are metal particles. In the present invention and this specification, a layer containing metal particles as a magnetic material corresponds to a "magnetic layer".

[0060] Magnetic particles can be of any shape, such as spherical, needle-shaped, or flattened. Flattened particles are preferred from the viewpoint of improving the shielding performance of electromagnetic shielding materials because they have a small demagnetizing field in the in-plane direction, resulting in high magnetic permeability. In the present invention and this specification, "flattened particles" refers to particles with an aspect ratio of 0.20 or less. For flattened particles and aspect ratios, refer to paragraphs 0031 to 0033 of WO2022 / 255022A1.

[0061] Examples of metal particles used as magnetic materials include Sendust (Fe-Si-Al alloy), Permalloy (Fe-Ni alloy), Molybdenum Permalloy (Fe-Ni-Mo alloy), Fe-Si alloy, Fe-Cr alloy, Fe-containing alloys generally called iron-based amorphous alloys, Co-containing alloys generally called cobalt-based amorphous alloys, alloys generally called nanocrystalline alloys, iron, Permendur (Fe-Co alloy), and other particles. Among these, Sendust is preferred because it exhibits high saturation magnetic flux density and relative permeability. In addition to the constituent elements of the metal (including alloys), the metal particles may contain elements contained in additives that can be optionally added and / or elements contained in impurities that may be unintentionally introduced during the manufacturing process of the metal particles, in any desired proportion. In metal particles, the content of constituent elements of the metal (including alloys) is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, and may also be 100% by mass, less than 100% by mass, 99.9% by mass or less, or 99.0% by mass or less.

[0062] The content of magnetic particles in the above magnetic layer can be, for example, 50% by mass or more, 60% by mass or more, 70% by mass or more, or 80% by mass or more, with respect to the total mass of the magnetic layer, and can also be, for example, 100% by mass or less, 98% by mass or less, or 95% by mass or less.

[0063] As the magnetic layer, one embodiment can be a sintered body of ferrite particles (ferrite plate), etc. Considering that the electromagnetic wave shielding material may need to be cut to a desired size or be bent into a desired shape, a magnetic layer containing resin is preferred over a sintered ferrite plate.

[0064] (Resin) The magnetic layer may contain a resin, and may contain a magnetic material (e.g., magnetic particles) and a resin. In the present invention and this specification, "resin" means polymer, and also includes rubber and elastomer. Polymers include homopolymers and copolymers. Rubber includes natural rubber and synthetic rubber. Elastomer is a polymer that exhibits elastic deformation. In the magnetic layer, the same or different resins may be crosslinked with a curing agent or the like. In the present invention and this specification, a layer containing both a magnetic material and a resin corresponds to a "magnetic layer". In a magnetic layer containing a magnetic material and a resin, the resin content may be, for example, 1 part by mass or more, 3 parts by mass or more, or 5 parts by mass or more per 100 parts by mass of magnetic material, or 30 parts by mass or less, or 25 parts by mass or less.

[0065] Resins can act as binders in the magnetic layer. Examples of resins included in the magnetic layer include conventionally known thermoplastic resins, thermosetting resins, UV-curable resins, radiation-curable resins, rubber-based materials, and elastomers. Specific examples include polyester resins, polyethylene resins, polyvinyl chloride resins, polyvinyl butyral resins, polyurethane resins, polyester urethane resins, cellulose resins, acrylic resins, ABS (acrylonitrile-butadiene-styrene) resins, nitrile-butadiene rubbers, styrene-butadiene rubbers, epoxy resins, phenolic resins, amide resins, silicone resins, styrene elastomers, olefin elastomers, vinyl chloride elastomers, polyester elastomers, polyamide elastomers, polyurethane elastomers, and acrylic elastomers. In the present invention and this specification, the term "urethane resin" is used as a general term for resins having urethane bonds.

[0066] In addition to the above components, the magnetic layer may also contain one or more known additives in any amount, such as curing agents, curing accelerators, dispersants, stabilizers, and crosslinking agents (e.g., coupling agents).

[0067] The curing agent can play a role in improving the strength and durability of the magnetic layer. Examples of curing agents included in the magnetic layer include thermosetting resins, photocurable resins (e.g., UV-curable resins, radiation-curable resins, etc.), moisture-curable resins, polymerization initiators, and reaction catalysts. Specific examples include isocyanates, polyols, epoxy resins, acid anhydrides, polyamines, phenolic resins, unsaturated polyester resins, urea resins, and diallyl phthalates. Some or all of the curing agent may be present in the magnetic layer in the form after the curing reaction.

[0068] Examples of isocyanates include aliphatic polyisocyanates, aromatic polyisocyanates, aromatic aliphatic polyisocyanates, and alicyclic polyisocyanates. Specific examples of aliphatic polyisocyanates include HDI (Hexamethylene disocyanate), the TMP (Trimethyrolpropane) adduct of HDI, the biuret adduct of HDI, and the isocyanurate adduct of HDI. Specific examples of aromatic polyisocyanates include TDI (Tolylene disocyanate), the adduct of TDI with a polyol compound (e.g., the TMP adduct of TDI), the biuret adduct of TDI, and the isocyanurate adduct of TDI. Specific examples of aromatic aliphatic polyisocyanates include XDI (Xylylene Disocyanate), the TMP adduct of XDI, the biuret of XDI, and the isocyanurate of XDI. Specific examples of alicyclic polyisocyanates include IPDI (Isophorone Disocyanate), the TMP adduct of IPDI, the biuret of IPDI, and the isocyanurate of IPDI.

[0069] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol epoxy resin, naphthol novolac epoxy resin, phenol novolac type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiroring-containing epoxy resin, cyclohexanedimethanol type epoxy resin, naphthylene ether type epoxy resin, and trimethylol type epoxy resin. Epoxy resins may be used individually or in combination of two or more types in any proportion. A composition containing epoxy resin can be cured by the ring-opening of the epoxy groups contained in the epoxy resin upon heating, forming a cross-linked structure. In a magnetic layer formed by curing a composition containing epoxy resin, some or all of the epoxy groups contained in the epoxy resin may be present in a state where they have opened their rings and formed a cross-linked structure.

[0070] Examples of reaction catalysts include imidazoles, sulfonic acids, DBU (1,8-diazabicyclo[5.4.0]-7-undecene) salts, amines, heavy metals, acids, and cyclic ethers.

[0071] For example, a magnetic layer formed using a magnetic layer-forming composition containing a urethane resin, an epoxy resin, and an isocyanate may include a urethane resin and a resin having a substructure represented by the following formula 1. In formula 1, * represents the bonding position with adjacent atoms.

[0072]

[0073] The substructure represented by formula 1 is an amino group derived from the isocyanate group of the isocyanate (for example, an isocyanate group and H ２It can be formed by the reaction of an amino group (generated by reaction with O) and an epoxy group of the epoxy resin. In the magnetic layer, the resin having the substructure represented by formula 1 and the urethane resin may or may not be crosslinked by a curing agent or the like. The same applies to the resin having one or more substructures selected from the group consisting of the substructure represented by formula 1-1, the substructure represented by formula 1-2, and the substructure represented by formula 1-3 and the urethane resin.

[0074] In one embodiment, a magnetic layer formed using a magnetic layer-forming composition comprising a urethane resin, an epoxy resin, and an isocyanate may include a urethane resin and a resin having one or more substructures selected from the group consisting of a substructure represented by formula 1-1, a substructure represented by formula 1-2, and a substructure represented by formula 1-3. In formulas 1-1, 1-2, and 1-3, * represents the bonding position with an adjacent atom. Each of the substructures represented by formulas 1-1, 1-2, and 1-3 includes the substructure represented by formula 1. In another embodiment, the resin included in the magnetic layer may be a resin having a substructure represented by formula 1, but not having the substructures represented by formulas 1-1, 1-2, and 1-3.

[0075]

[0076] For example, a magnetic layer formed using a magnetic layer-forming composition containing a urethane resin, an epoxy resin, and HDI may include a urethane resin and a resin having a substructure represented by formula 1-1. A magnetic layer formed using a magnetic layer-forming composition containing a urethane resin, an epoxy resin, and HDI may include a urethane resin and a resin having a substructure represented by formula 1-2 and / or a substructure represented by formula 1-3.

[0077] It is preferable for the magnetic layer to include a urethane resin and a resin having a substructure represented by Formula 1, from the viewpoint of improving adhesion between the magnetic layer and adjacent layers, and from the viewpoint of improving the strength of the magnetic layer. From these viewpoints, it is more preferable for the magnetic layer to include a urethane resin and a resin having one or more substructures selected from the group consisting of Formulas 1-1, 1-2, and 1-3.

[0078] The presence of urethane resin and resin having the above-mentioned substructure in the magnetic layer can be confirmed by known methods.

[0079] When the electromagnetic shielding material contains only one magnetic layer, the thickness of this single magnetic layer can be, for example, 5 μm or more, and from the viewpoint of further improving the shielding ability of the electromagnetic shielding material, it is preferable to have a thickness of 10 μm or more, and more preferably 20 μm or more. On the other hand, the thickness of this single magnetic layer can be, for example, 100 μm or less or 90 μm or less, and from the viewpoint of improving moldability, it is preferable to have a thickness of less than 90 μm, more preferably 80 μm or less, and even more preferably 70 μm or less. When the electromagnetic shielding material contains two or more magnetic layers, the thickness of each of these two or more magnetic layers (i.e., the thickness per layer) can be, for example, 5 μm or more, and from the viewpoint of further improving the shielding ability of the electromagnetic shielding material, it is preferable to have a thickness of 10 μm or more, and more preferably 20 μm or more. On the other hand, the thickness per layer can be, for example, 100 μm or less or 90 μm or less, and from the viewpoint of improving moldability, it is preferable to have a thickness of less than 90 μm, and more preferably 80 μm or less. The thickness of each of the two or more magnetic layers can be the same or different.

[0080] <Method for Manufacturing Electromagnetic Wave Shielding Material> (Method for Forming a Magnetic Layer) The magnetic layer described above can be produced, for example, by applying a magnetic layer-forming composition and drying the resulting coating layer. The magnetic layer-forming composition may contain the components described above and may optionally contain one or more solvents. Examples of solvents include various organic solvents, such as ketone solvents like acetone, methyl ethyl ketone, and cyclohexanone; acetic acid ester solvents like ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols like cellosolve and butyl carbitol; aromatic hydrocarbon solvents like toluene and xylene; and amide solvents like dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. One solvent selected considering the solubility of the components used in preparing the magnetic layer-forming composition, or two or more solvents mixed in any ratio, can be used. The solvent content of the magnetic layer-forming composition is not particularly limited and should be determined considering the coatability of the magnetic layer-forming composition.

[0081] A magnetic layer-forming composition can be prepared by sequentially mixing various components in any order or by mixing them simultaneously. Furthermore, if necessary, dispersion can be performed using known dispersers such as ball mills, bead mills, sand mills, and roll mills, and / or stirring can be performed using known stirrers such as shaking stirrers.

[0082] The magnetic layer-forming composition can be applied, for example, to a support. The application can be carried out using known coating equipment such as a blade coater or die coater. The application can be performed using a so-called roll-to-roll method or a batch method.

[0083] Examples of supports to which the magnetic layer-forming composition is applied include films of various resins such as polyester (PET), polyethylene terephthalate (PEN), polycarbonate (PC), acrylic (PMMA), cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. For these resin films, refer to paragraphs 0081 to 0086 of Japanese Patent Application Publication No. 2015-187260. As the support, a support that has been subjected to a release treatment by a known method on the surface to which the magnetic layer-forming composition is applied (the surface to be coated) can be used. One form of the release treatment is the formation of a release layer. For the release layer, refer to paragraph 0084 of Japanese Patent Application Publication No. 2015-187260. Alternatively, a commercially available pre-released resin film can be used as the support. By using a support with a release treatment on the surface to be coated, the magnetic layer and the support can be easily separated after film formation.

[0084] Furthermore, the magnetic layer-forming composition can also be applied to the surface of a metal layer, a resin-containing layer, etc. For example, it is possible to create a partial structure of an electromagnetic wave shielding material by applying the magnetic layer-forming composition to the surface of a metal layer or a resin-containing layer and, if necessary, performing the magnetic layer pressure treatment described later. As an example, a partial structure of "resin-containing layer / metal layer / resin-containing layer / magnetic layer" can be created by applying a magnetic layer-forming coating liquid to the surface of a resin-containing layer of a laminate having a layer configuration of "resin-containing layer / metal layer / resin-containing layer" and, if necessary, performing the magnetic layer pressure treatment described later. By pressing together two of these "resin-containing layer / metal layer / resin-containing layer / magnetic layer" partial structures with the magnetic layer sides facing each other and applying pressure and heat, an electromagnetic wave shielding material having a layer configuration of "resin-containing layer / metal layer / resin-containing layer / magnetic layer / resin-containing layer / metal layer / resin-containing layer" can be created. The resin-containing layer in the above layer configuration can be a single layer of resin-containing layer or a resin-containing layer laminate.

[0085] The coating layer formed by applying the magnetic layer-forming composition can be dried by known methods such as heating or blowing hot air. The drying process can be carried out under conditions that allow the solvent contained in the magnetic layer-forming composition to volatilize. For example, the drying process can be carried out in a heated atmosphere with an ambient temperature of 80 to 150°C for 1 minute to 2 hours.

[0086] (Pressurization of the magnetic layer) The magnetic layer can also be subjected to pressure treatment after film formation. By subjecting the magnetic layer containing magnetic particles to pressure treatment, the density of magnetic particles within the magnetic layer can be increased.

[0087] Pressurization can be performed by applying pressure in the thickness direction of the magnetic layer using a flat plate press, a roll press, or the like. A flat plate press places the object to be pressed between two flat press plates positioned vertically, and applies pressure to the object by bringing the two press plates together using mechanical or hydraulic pressure. A roll press passes the object to be pressed between rotating pressure rolls positioned vertically, and applies pressure by applying mechanical or hydraulic pressure to the pressure rolls during this process, or by making the distance between the pressure rolls smaller than the thickness of the object to be pressed.

[0088] The pressure during pressurization can be set arbitrarily. For example, in the case of a flat plate press, it can be set to 1 to 50 N (Newtons) / mm ２In the case of a roll press, for example, the linear pressure is 20 to 400 N / mm. The pressurization time can be set arbitrarily. When using a flat plate press, for example, it is 5 seconds to 30 minutes. When using a roll press, the pressurization time can be controlled by the conveying speed of the object to be pressed, for example, the conveying speed is 10 cm / min to 200 m / min. The material of the press plate and pressurization roll can be arbitrarily selected from metal, ceramics, plastic, rubber, etc. During the pressurization process, it is also possible to apply heat to both the upper and lower press plates of a plate press or one side of the upper and lower rolls of a roll press or one side of the rolls of a roll press. Heating can soften the magnetic layer, thereby obtaining a high compression effect when pressure is applied. The temperature during heating can be set arbitrarily, for example, between 50°C and 200°C. The above-mentioned temperature during heating can be the internal temperature of the press plate or roll. This temperature can be measured by a thermometer installed inside the press plate or roll. After heating and pressing in a plate press, the magnetic layer can be removed by separating the press plates while they are still hot, for example. Alternatively, the press plates can be cooled by water cooling, air cooling, or other methods while maintaining pressure, and then separated to remove the magnetic layer. In a roll press, the magnetic layer can be cooled by water cooling, air cooling, or other methods immediately after pressing. It is also possible to repeat the pressing process two or more times. If the magnetic layer is formed on a release film, the pressing process can be performed, for example, while the magnetic layer is laminated on the release film. Alternatively, the magnetic layer can be peeled off the release film and pressed as a single layer.

[0089] (Bonding of various layers) Adhesive layers or bonding layers can be used to bond various layers. The adhesive layers and bonding layers are as described above. In addition, in the electromagnetic shielding material described above, two adjacent layers can be bonded together by applying pressure and heat, for example. A plate press, a roll press, etc. can be used for bonding. For example, when a magnetic layer is placed as a layer that is in direct contact (i.e., adjacent) to an adjacent layer, the magnetic layer softens during the bonding process, promoting contact with the surface of the adjacent layer, thereby bonding the magnetic layer and the adjacent layer without the need for other layers in between. The pressure during bonding can be set arbitrarily. In the case of a plate press, for example, 1 to 50 N (Newtons) / mm ２ In the case of a roll press, for example, the linear pressure is 20 to 400 N / mm. The pressing time during crimping can be set arbitrarily. When using a plate press, for example, it is 5 seconds to 30 minutes. When using a roll press, it can be controlled by the conveying speed of the object to be pressed, for example, the conveying speed is 10 cm / min to 200 m / min. The temperature during crimping can be selected arbitrarily, for example, between 20°C and 200°C. The above temperature during crimping can be, for example, the internal temperature of the press plate or roll.

[0090] (Arrangement of Metal Foil-Containing Layer) At any stage in the manufacturing process of the electromagnetic wave shielding material, the metal foil-containing layer can be arranged on the metal layer by removing part or all of the outer edge of the resin-containing layer located at the outermost layer (along with any other layer if there is another layer between it and the metal layer) to expose a portion of the surface of the underlying metal layer, and then laminating the metal foil-containing layer onto the surface of the exposed portion. For example, a sheet-like (or film-like) metal foil-containing layer can be cut into a shape with an opening, and the resin-containing layer from which the outer edge of any width has been removed can be positioned within the opening and laminated to the surface of the metal layer. For example, in this way, the entire circumference of the side surface of the resin-containing layer can be surrounded by the metal foil-containing layer. If there is another layer between the outermost resin-containing layer and the metal layer, the entire circumference of the side surface of that layer can also be surrounded by the metal foil-containing layer. Thus, in one embodiment, the metal foil-containing layer can be a discontinuous layer having one opening.

[0091] The electromagnetic shielding material described above can be incorporated into electronic components or electronic devices in any shape. The electromagnetic shielding material can be in sheet form, and its size is not particularly limited. In this invention and specification, "sheet" is synonymous with "film". Furthermore, the electromagnetic shielding material can be a three-dimensional molded product obtained by three-dimensionally molding a sheet-like electromagnetic shielding material, or it can be a sheet-like electromagnetic shielding material for three-dimensional molding. Various molding methods such as die press molding, vacuum forming, and pressure forming can be used as three-dimensional molding methods. Regarding molding methods, molding performed without heating the object to be molded and / or the mold, or by heating without raising the temperature too much, is generally called cold forming. In one embodiment, the electromagnetic shielding material described above can be molded by cold forming such as deep drawing or stretching. Deep drawing is a molding method in which a sheet-like object to be molded is pressed using a pair of female and male molds to form various bottomed containers of various shapes such as cylinders, rectangular tubes, and cones. In contrast, stretch molding is a method of forming a molded product from a sheet-like material in which a curved surface protrudes from a flat surface. Stretch molding can be performed using only a male mold, without a female mold. Deep drawing is broadly classified into deep drawing and shallow drawing. Shallow drawing produces molded products with shallow depths, while deep drawing produces molded products with greater depths (for example, deeper than the diameter of a cylinder or cone, or the length of one side of a pyramid). For three-dimensional molding methods, known techniques can be applied.

[0092] [Electronic Components] One aspect of the present invention relates to an electronic component including the above-mentioned electromagnetic shielding material. Examples of the above-mentioned electronic component include various electronic components such as electronic components included in electronic devices such as mobile phones, personal digital assistants, and medical devices, semiconductor elements, capacitors, coils, and cables. The above-mentioned electromagnetic shielding material can, for example, be three-dimensionally molded into any shape according to the shape of the electronic component and placed inside the electronic component, or it can be three-dimensionally molded into the shape of a cover material that covers the outside of the electronic component and placed as a cover material. Alternatively, it can be three-dimensionally molded into a cylindrical shape and placed as a cover material that covers the outside of a cable.

[0093] [Electronic Devices] One aspect of the present invention relates to electronic devices including the electromagnetic shielding material described above. Examples of such electronic devices include mobile phones, personal digital assistants, medical devices, and other electronic devices; electronic devices including various electronic components such as semiconductor elements, capacitors, coils, and cables; and electronic devices in which electronic components are mounted on a circuit board. Such electronic devices may include the electromagnetic shielding material as a component of the electronic components contained in them. Furthermore, the electromagnetic shielding material can be placed inside the electronic device, or as a cover material covering the outside of the electronic device. Alternatively, it can be formed into a cylindrical shape and used as a cover material covering the outside of a cable.

[0094] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the embodiments shown in the examples.

[0095] [Example 1] <Preparation of resin-containing laminate> (Coating of adhesive) Adhesive (AS-60HD manufactured by Toagosei Co., Ltd.) was applied to one surface of a PET film (Lumirror #38-S10 manufactured by Toray Industries, Inc.) using a bar coater (No. 8 manufactured by AS ONE Corporation), dried in a fume hood for 20 minutes, and then dried in a drying apparatus with an internal atmosphere temperature of 80°C for 10 minutes. In this way, a laminate of a resin layer (PET film) and an adhesive layer (resin-containing laminate) was prepared.

[0096] <Preparation of Metal Layer with Resin-Containing Layer Laminate> Two resin-containing layer laminates were prepared using the method described above. A metal layer (aluminum foil model number A1N30-O, manufactured by Takeuchi Metal Foil & Powder Co., Ltd.) was placed on top of the resin-containing layer laminate with the adhesive layer facing upwards. The adhesive layer of the other resin-containing layer laminate was placed on top of the other resin-containing layer laminate with the adhesive layer facing the metal layer. The resulting "resin-containing layer laminate / metal layer / resin-containing layer laminate" was then sandwiched between two Teflon® sheets. The upper and lower press plates of a plate press (Mini Test Press, manufactured by Toyo Seiki Co., Ltd.) were heated to 140°C (internal temperature of the press plate), and the laminate was subjected to a load of 30 N / mm². ２The pressure was maintained for 10 minutes. While maintaining the pressure, the upper and lower press plates were cooled to 50°C (internal temperature of the press plates), then the metal layer with resin-containing layer laminate (a laminate having a layer structure of "resin-containing layer laminate / metal layer / resin-containing layer laminate") was taken out from between the two Teflon (registered trademark) sheets.

[0097] <Preparation of Composition for Forming Magnetic Layer (Coating Liquid)> Into a plastic bottle, were added:Fe-Si-Al flat-shaped magnetic particles (Sendust manufactured by MKT, trade name: MFS-SUH): 100 g, Urethane resin (urethane resin solution manufactured by Tosoh Corporation, trade name: Nipporan 5120): 53.9 g, Epoxy resin (modified epoxy resin manufactured by DIC Corporation, trade name: HP-A-4860): 6.2 g, Cyclohexanone: 183.2 g, and the mixture was mixed for 1 hour using a shaker-type stirrer. After the above mixing, was added: Curing agent (HDI (hexamethylene diisocyanate) manufactured by Asahi Kasei Corporation, trade name: Duranate TPA-100): 2.4 g, and the mixture was mixed for 10 minutes using a shaker-type stirrer to prepare a coating liquid (composition for forming a magnetic layer). The magnetic layer produced using the above coating liquid contains a urethane resin and a resin having a partial structure represented by Formula 1-1.

[0098] <Production of Magnetic Layer> (Film Formation of Magnetic Layer) The coating liquid was applied onto the surface of one resin-containing layer of the metal layer with resin-containing layer laminate using a blade coater with a coating gap of 380 µm, and dried for 8 minutes in a drying apparatus with an internal atmospheric temperature of 90°C to form a magnetic layer.

[0099] <Production of Electromagnetic Wave Shielding Material> By the above method, two metal layers with resin-containing layer having a magnetic layer formed thereon (a laminate having a layer structure of "resin-containing layer laminate / metal layer / resin-containing layer laminate / magnetic layer") were produced. The two laminates were stacked with their magnetic layers facing each other, and sandwiched between two Teflon (registered trademark) sheets. The upper and lower press plates of a plate press (Mini Test Press manufactured by Toyo Seiki Co., Ltd.) were heated to 140°C (internal temperature of the press plates), and the above laminate was subjected to 3 N / mm ２The pressure was applied and held for 10 minutes. After the upper and lower press plates were cooled to 50°C (internal temperature of the press plates) while maintaining the pressure, the electromagnetic shielding material was removed from between the two Teflon® sheets. The electromagnetic shielding material was cut to a size of 150 x 150 mm. Using an ultrasonic cutter (Honda Electronics ZO-80), a 12 mm wide area on the outer edge of the laminated portion (i.e., resin-containing laminate) between the resin layer on the surface on both sides of the cut electromagnetic shielding material and the adhesive layer located directly beneath it was removed. The size of the resin-containing laminate after the above area was removed is 126 mm x 126 mm. Figure 3 shows a plan view of the state after the outer edges of the outermost resin layer and the adhesive layer directly beneath it have been removed. As a metal foil-containing layer, a copper foil sheet (model number CU-18C, manufactured by 3M Japan Ltd.) was cut to a shape with an outer dimension of 150 mm x 150 mm and an opening of 130 mm x 130 mm. The adhesive layer of the copper foil sheet was attached to the portion of the outer edge of the outermost layer on one side of the electromagnetic shielding material where the resin-containing layer laminate had been removed, with the adhesive layer of the copper foil sheet facing the metal layer side of the electromagnetic shielding material. The same copper foil sheet was attached to the other side of the electromagnetic shielding material. The electromagnetic shielding material thus obtained was used as a sample for measuring shielding performance for the evaluation described later.

[0100] The copper foil sheet described above is a two-layer laminate consisting of copper foil and an adhesive layer. It was confirmed using a digital multimeter (KU-2608, manufactured by Kaise Corporation) that the adhesive layer contained in the copper foil sheet is the conductive layer (conductive adhesive layer) described above. Therefore, the shielding performance measurement sample (electromagnetic wave shielding material) of Example 1 satisfies (3) described above regarding the laminate structure. Furthermore, the shielding performance measurement sample (electromagnetic wave shielding material) of Example 1 also satisfies (1) and (2) described above regarding the laminate, and also satisfies (4) as shown in the table below.

[0101] [Example 2] A shielding performance measurement sample (electromagnetic wave shielding material) was prepared by the method described in Example 1, except that the resin layer on the outermost layer on both sides was changed to a PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.).

[0102] [Example 3] A shielding performance measurement sample (electromagnetic wave shielding material) was prepared by the method described in Example 1, except that the resin layer on the outermost layer on both sides was changed to a PET film (Lumirror #50-S10 manufactured by Toray Industries, Inc.).

[0103] [Comparative Example 1] A shielding performance measurement sample (electromagnetic wave shielding material) was prepared by the method described for Example 2, except that the metal foil-containing layer was changed to a copper foil sheet (model number CU-35C, manufactured by 3M Japan Ltd). The copper foil sheet used in Comparative Example 1 is a two-layer laminate of copper foil and a conductive adhesive layer, and the copper foil is thicker than that of the copper foil sheets used in Examples 1 to 3 (see the table below).

[0104] [Comparative Example 2] A shielding performance measurement sample (electromagnetic wave shielding material) was prepared by the method described for Example 1, except that the outer edges of the resin-containing layer laminate were not removed on both sides and a metal foil-containing layer was not provided.

[0105] [Comparative Example 3] A shielding performance measurement sample (electromagnetic wave shielding material) was prepared by the same method as described for Comparative Example 1, except that the resin layer on the outermost layer on both sides was changed to a PET film (Lumirror #75-S10 manufactured by Toray Industries, Inc.).

[0106] [Comparative Example 4] A shielding performance measurement sample (electromagnetic wave shielding material) was prepared by the method described for Example 1, except that the resin layer on the outermost layer on both sides was changed to a PET film (Lumirror #75-S10 manufactured by Toray Industries, Inc.).

[0107] [Comparative Example 5] A shielding performance measurement sample (electromagnetic wave shielding material) was prepared by the method described for Example 1, except that the resin layer on the outermost layer on both sides was changed to a PET film (Lumirror #100-S10 manufactured by Toray Industries, Inc.).

[0108] Figure 4 shows cross-sectional views of the shielding performance measurement samples (electromagnetic shielding materials) of Examples 1 to 3. Figure 5 shows cross-sectional views of the shielding performance measurement samples (electromagnetic shielding materials) of Comparative Examples 1 to 3. Figure 6 shows cross-sectional views of the shielding performance measurement samples (electromagnetic shielding materials) of Comparative Examples 4 and 5. Each drawing is a schematic diagram, and the thickness ratios of the various layers shown in the figures differ from the actual thickness ratios.

[0109] [Measurement of Thickness of Each Layer and Calculation of Protrusion Height] For each of Examples 1 to 3 and Comparative Examples 1 to 5, after measuring the shielding capacity of the shielding capacity measurement sample (electromagnetic wave shielding material), the following method was used to process the cross-section of the electromagnetic wave shielding material to expose its cross-section. The electromagnetic wave shielding material, cut to a size of 3 mm x 3 mm, was embedded in resin, and the cross-section of the shielding material was cut using an ion milling device (Hitachi High-Tech Corporation IM4000PLUS). The exposed cross-section of the electromagnetic wave shielding material was observed using a scanning electron microscope (Hitachi High-Tech Corporation SU8220) under conditions of an acceleration voltage of 2 kV and a magnification of 100x, and a backscattered electron image was obtained. Using the scale bar as a reference from the obtained image, the thickness of five randomly selected locations was measured for each layer shown in the table below, and the arithmetic mean of these measurements was taken as the thickness of each layer, as shown in the table below. For each of the metal foil, conductive adhesive layer, outermost resin layer, and adhesive layer adjacent to the outermost resin layer, the thickness of each layer on one side of the electromagnetic shielding material was the same as the thickness of each layer on the other side. From the above thickness measurement results, the protrusion height of (4) described above regarding the laminated structure was calculated. In each of the electromagnetic shielding materials of Examples 1 to 3 and Comparative Examples 1 to 5, the thickness of the magnetic layer was 40 μm, the thickness of each metal layer was 50 μm, the thickness of the resin layer located between the magnetic layer and the metal layer was 100 μm, and the thickness of the adhesive layer located between the magnetic layer and the metal layer was 6 μm.

[0110] [Evaluation of Electromagnetic Shielding Performance (KEC Method)] The electromagnetic shielding performance of each shielding performance measurement sample (electromagnetic shielding material) in the examples and comparative examples was evaluated using the KEC method evaluation apparatus described below. "KEC" is an abbreviation for Kansai Electronics Industry Promotion Center. The KEC method evaluation apparatus has a pair of antennas installed facing each other. A high-frequency signal (measurement signal) with a frequency of 10 MHz generated by a signal generator is converted into a measurement radio wave by the transmitting antenna, received by the receiving antenna, and the measurement signal is amplified by a preamplifier and the received voltage is measured by a spectrum analyzer. When the received voltage when the measurement sample (electromagnetic shielding material) is not placed is denoted as Blank [dBm], and the received voltage when the measurement sample is placed is denoted as Sample [dBm], the shielding performance can be calculated using the following formula. "dB" indicates decibels, and "dBm" indicates decibel milliwatts. Shielding performance [dB] = Blank [dBm] - Sample [dBm]

[0111] The results of the above evaluation are shown in the table below.

[0112]

[0113]

[0114] Figure 7 shows a cross-sectional view of the KEC method evaluation apparatus used in the above evaluation, Figure 8 shows a plan view, and Figure 9 shows a measurement explanatory diagram. The antenna of the KEC method evaluation apparatus is partially exposed to the outside from the measurement space provided in the center of the metal housing, and the metal coating has been removed from the tip, exposing the signal wire. High-frequency signals are emitted as radio waves from this exposed part into the measurement space, and the receiving side similarly receives the radio waves at the exposed part without the metal coating and converts them into signals. The width of the opening is 50 mm, and the width of the measurement sample is 150 mm. The measurement sample outside the opening is in contact with the metal housing on both the transmitting and receiving sides. The metal housing is connected to ground, and when the measurement radio waves emitted from the transmitting antenna are converted into current in the measurement sample, the current flows to ground, so the received voltage of the receiving antenna decreases, i.e., the shielding performance increases. In Comparative Example 2, since the outermost layer of the electromagnetic wave shielding material is only a resin layer, conductivity between the metal housing and the metal layer is hindered. In Comparative Examples 3 to 5, the portion in contact with the metal housing is the outermost resin layer, thus hindering conductivity between the metal housing and the metal layer. In contrast, in Examples 1 to 3, the inventors believe that by ensuring conductivity through the outermost metal foil-containing layer, the measured radio waves are converted into electric current in the metal layer of the electromagnetic wave shielding material, and this current flows to the ground via the metal foil-containing layer and the metal housing, contributing to improved shielding performance. On the other hand, in Comparative Example 1, the inventors surmise that the space between the metal housing and the resin layer is larger than in Examples 1 to 3, and that the resonance and / or amplification of electromagnetic waves in the space hinders the improvement of shielding performance.

[0115] One aspect of the present invention is useful in the technical fields of various electronic components and various electronic devices.

Claims

1. An electromagnetic wave shielding material having one or two laminated structures that satisfy the following (1) to (4): (1) A metal foil-containing layer, whose surface is exposed on the outermost surface, surrounds at least a portion of the side surface of the resin-containing layer; (2) The resin-containing layer and the metal layer are adjacent to each other directly or via other layers; (3) At least a portion of the outer peripheral region of the surface of the metal layer on the side of the resin-containing layer is a region on which the resin-containing layer is not present, and the region is electrically connected to the metal foil-containing layer; (4) The protruding height of the metal foil-containing layer in the thickness direction of the electromagnetic wave shielding material is 0 μm or more and 30 μm or less, with the outermost surface of the resin-containing layer being 0 μm.

2. The electromagnetic wave shielding material according to claim 1, having two of the aforementioned laminated structures.

3. The electromagnetic wave shielding material according to claim 2, further comprising a magnetic layer between the metal layer of one of the two laminated structures and the metal layer of the other laminated structure.

4. The electromagnetic wave shielding material according to claim 3, wherein the magnetic layer is a layer containing magnetic particles and resin.

5. The electromagnetic wave shielding material according to claim 1, wherein the protruding height of the metal foil-containing layer in (4) is 1 μm or more and 30 μm or less.

6. The electromagnetic wave shielding material according to claim 1, wherein the protruding height of the metal foil-containing layer in (4) is 10 μm or more and 20 μm or less.

7. The electromagnetic wave shielding material according to claim 1, comprising two of the aforementioned laminated structures, wherein a magnetic layer is further provided between the metal layer of one of the two laminated structures and the metal layer of the other laminated structure, the magnetic layer is a layer containing magnetic particles and resin, and the protruding height of the metal foil-containing layer in (4) is 1 μm or more and 30 μm or less.

8. The electromagnetic wave shielding material according to claim 7, wherein the protruding height of the metal foil-containing layer in (4) is 10 μm or more and 20 μm or less.

9. An electronic component comprising an electromagnetic shielding material according to any one of claims 1 to 8.

10. Electronic equipment comprising an electromagnetic shielding material according to any one of claims 1 to 8.

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