Electromagnetic wave shielding material, electronic component, and electronic device

Abstract

Provided are: an electromagnetic wave shielding material, as well as an electronic component and an electronic device comprising the electromagnetic wave shielding material, the material comprising one or more magnetic layers interposed between two metal layers, and further comprising a resin-containing layer on both sides of at least one of the two metal layers, there being a difference of 20 μm or less in thickness between the resin-containing layers on both sides of the metal layer.

Description

Electromagnetic wave shielding materials, electronic components and electronic equipment

[0001] The present invention relates to an electromagnetic wave shielding material, an electronic component, and an electronic device.

[0002] In recent years, electromagnetic wave shielding materials have been attracting attention as materials for reducing the effects of electromagnetic waves in various electronic components and electronic devices (see, for example, Patent Document 1). Electromagnetic wave shielding materials can exhibit electromagnetic wave shielding performance (hereinafter also referred to as "shielding ability") by reflecting and / or attenuating electromagnetic waves incident on the electromagnetic wave shielding material.

[0003] WO2022 / 255022A1

[0004] Patent Document 1 discloses an electromagnetic wave shielding material having one or more magnetic layers sandwiched between two metal layers. Having such a multilayer structure in which a magnetic layer is sandwiched between two metal layers can contribute to the electromagnetic wave shielding material exhibiting high shielding ability (see paragraph 0025 of Patent Document 1).

[0005] Electromagnetic wave shielding materials may be exposed to temperature changes when incorporated into electronic components or electronic devices, and therefore it is desirable for the electromagnetic wave shielding materials to have excellent durability after being exposed to temperature changes.

[0006] In view of the above, one aspect of the present invention aims to provide an electromagnetic wave shielding material having one or more magnetic layers sandwiched between two metal layers, which has excellent durability after being exposed to temperature changes.

[0007] One aspect of the present invention is as follows: [1] An electromagnetic shielding material comprising one or more magnetic layers sandwiched between two metal layers, further comprising resin-containing layers on both sides of at least one of the two metal layers, wherein the difference in thickness between the resin-containing layers on both sides of the metal layer is 20 μm or less. [2] The electromagnetic shielding material according to [1], wherein the total thickness of the resin-containing layers on both sides of the metal layer is 30 μm or more. [3] The electromagnetic shielding material according to [1] or [2], wherein the total thickness of the resin-containing layers included in the electromagnetic shielding material is less than 100 μm. [4] The electromagnetic shielding material according to any one of [1] to [3], wherein at least one of the resin-containing layers on both sides of the metal layer contains one or more flame-retardant layers. [5] The electromagnetic shielding material according to any one of [2] to [4], wherein the total thickness of the resin-containing layers included in the electromagnetic shielding material is less than 100 μm, and at least one of the resin-containing layers on both sides of the metal layer contains one or more flame-retardant layers. [6] The electromagnetic shielding material according to any one of [1] to [5], which has a resin-containing layer on both sides of each of the two metal layers. [7] The electromagnetic shielding material according to [6], in which the difference in thickness between the resin-containing layers located on both sides of one of the two metal layers is 20 μm or less, and the difference in thickness between the resin-containing layers located on both sides of the other metal layer is 20 μm or less. [8] The electromagnetic shielding material according to [6] or [7], in which the total thickness of the resin-containing layers located on both sides of one of the two metal layers is 30 μm or more, and the total thickness of the resin-containing layers located on both sides of the other metal layer is 30 μm or more. [9] The electromagnetic shielding material according to any one of [6] to [8], in which the total thickness of the resin-containing layers included in the electromagnetic shielding material is less than 100 μm.

[10] The electromagnetic shielding material according to any one of [6] to [9], in which at least one of the resin-containing layers includes one or more flame-retardant layers.

[11] The electromagnetic wave shielding material according to any one of [7] to

[10] , wherein the resin-containing layers located on both sides of one of the two metal layers have a total thickness of 30 μm or more, and the resin-containing layers located on both sides of the other metal layer have a total thickness of 30 μm or more, the total thickness of the resin-containing layers included in the electromagnetic wave shielding material is less than 100 μm, and at least one of the resin-containing layers includes one or more flame-retardant layers.

[12] The magnetic layer comprises a urethane resin and the following formula 1: (in formula 1, * represents the bonding position between adjacent atoms), and a resin having a partial structure represented by the following formula 1-1, the following formula 1-2, and the following formula 1-3: (in formula 1-1, formula 1-2 and formula 1-3, * represents the bonding position to adjacent atoms), and a resin having one or more partial structures selected from the group consisting of:

[14] A urethane resin and a compound represented by the following formula 1: (in formula 1, * represents the bonding position between adjacent atoms), and a magnetic layer containing:

[15] A urethane resin, and a partial structure represented by the following formula 1-1, a partial structure represented by the following formula 1-2, and a partial structure represented by the following formula 1-3: (In Formula 1-1, Formula 1-2, and Formula 1-3, * represents the bonding position to adjacent atoms), and an electromagnetic wave shielding material having a resin having one or more partial structures selected from the group consisting of:

[16] The electromagnetic wave shielding material according to

[14] or

[15] , which has the magnetic layer between two resin-containing layers.

[17] An electronic component comprising the electromagnetic wave shielding material according to any one of [1] to

[16] .

[18] An electronic device comprising the electromagnetic wave shielding material according to any one of [1] to

[16] .

[0008] According to one aspect of the present invention, there is provided an electromagnetic wave shielding material having one or more magnetic layers sandwiched between two metal layers, the electromagnetic wave shielding material having excellent durability after exposure to temperature changes, and electronic components and electronic devices including the electromagnetic wave shielding material.

[0009] [Electromagnetic Shielding Material] One aspect of the present invention relates to an electromagnetic shielding material, which includes one or more magnetic layers sandwiched between two metal layers, and further includes resin-containing layers on both sides of at least one of the two metal layers, wherein the difference in thickness between the resin-containing layers on both sides of the metal layer is 20 μm or less.

[0010] In the present invention and this specification, the term "electromagnetic wave shielding material" refers to a material that can exhibit shielding ability against electromagnetic waves of at least one frequency or at least a part of a frequency band. "Electromagnetic waves" include magnetic waves and electric waves. An "electromagnetic wave shielding material" can be a material that can exhibit shielding ability against one or both of magnetic waves of at least one frequency or at least a part of a frequency band, and electric waves of at least one frequency or at least a part of a frequency band.

[0011] In the present invention and this specification, the term "magnetic" means ferromagnetic property.

[0012] In the present invention and this specification, the thickness of each layer included in the electromagnetic shielding material is determined by taking an image of a cross section exposed by a known method using a scanning electron microscope (SEM) and then calculating the arithmetic mean of the thicknesses at five randomly selected points in the resulting SEM image.

[0013] The electromagnetic wave shielding material has one or more magnetic layers sandwiched between two metal layers. As described above, having a multilayer structure in which a magnetic layer is sandwiched between two metal layers can contribute to the electromagnetic wave shielding material exhibiting high shielding capabilities. Furthermore, the present inventors believe that having an electromagnetic wave shielding material further comprising resin-containing layers on both sides of at least one of the two metal layers contributes to improving the elongation of the electromagnetic wave shielding material. Electromagnetic wave shielding materials with excellent elongation are preferable from the standpoint of, for example, ease of shape formation during molding. On the other hand, resin-containing layers tend to shrink and / or expand when subjected to temperature changes. The present inventors believe that this may cause peeling at the interface between the magnetic layer and adjacent layers and / or within the magnetic layer after an electromagnetic wave shielding material having one or more magnetic layers sandwiched between two metal layers and further comprising resin-containing layers on both sides of at least one of the two metal layers is exposed to temperature changes. In contrast, the present inventors believe that in the electromagnetic wave shielding material, the difference in thickness between the resin-containing layers on both sides of the metal layer being 20 μm or less contributes to suppressing stress from being generated inside the electromagnetic wave shielding material due to shrinkage and / or expansion of the resin-containing layer, thereby making it possible to suppress the occurrence of the above-mentioned peeling. However, the present invention is not limited to the present inventors' speculations described in this specification.

[0014] The electromagnetic wave shielding material will be described in more detail below.

[0015] <Magnetic Layer> (Magnetic Material) The magnetic layer is a layer containing a magnetic material. Examples of the magnetic material include magnetic particles. As the 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 combination in any ratio. Metal particles generally have a saturation magnetic flux density about two to three times that of ferrite particles, and therefore can maintain relative permeability and exhibit shielding ability without magnetic saturation even under strong magnetic fields. 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 is considered to be a "magnetic layer."

[0016] The magnetic particles can be particles of any shape, such as spherical, acicular, or flat. Flat-shaped particles are preferred from the perspective of improving the shielding ability of the electromagnetic wave shielding material, since they have a small demagnetizing field in the in-plane direction of the particles, resulting in high magnetic permeability. In the present invention and this specification, "flat-shaped particles" refers to particles with an aspect ratio of 0.20 or less. For details about flat-shaped particles and aspect ratios, see paragraphs 0031 to 0033 of WO2022 / 255022A1.

[0017] Metal Particles Examples of metal particles serving as the magnetic material include particles of sendust (Fe—Si—Al alloy), permalloy (Fe—Ni alloy), molybdenum permalloy (Fe—Ni—Mo alloy), Fe—Si alloy, Fe—Cr alloy, Fe-containing alloy generally referred to as iron-based amorphous alloy, Co-containing alloy generally referred to as cobalt-based amorphous alloy, alloy generally referred to as nanocrystalline alloy, iron, permendur (Fe—Co alloy), and the like. 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, in any content, elements contained in optional additives and / or elements contained in impurities that may be unintentionally mixed in during the manufacturing process of the metal particles. In the metal particles, the content of the 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.

[0018] The content of magnetic particles in the magnetic layer can be, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, or 80% by weight or more, relative to the total weight of the magnetic layer, and can be, for example, 100% by weight or less, 98% by weight or less, or 95% by weight or less.

[0019] In one embodiment, the magnetic layer may be a sintered body of ferrite particles (a ferrite plate), etc. Considering that the electromagnetic wave shielding material may be cut to a desired size or bent to a desired shape, a magnetic layer containing a resin is preferable to a sintered body such as a ferrite plate.

[0020] (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" refers to a polymer, including rubber and elastomer. Polymers include homopolymers and copolymers. Rubber includes natural rubber and synthetic rubber. Elastomers are polymers that exhibit 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 is considered to be a "magnetic layer." In a magnetic layer containing a magnetic material and a resin, the resin content may be, for example, 1 part by weight or more, 3 parts by weight or more, or 5 parts by weight or more, and 30 parts by weight or less, or 25 parts by weight or less, per 100 parts by weight of the magnetic material.

[0021] Resins can function as binders in the magnetic layer. Examples of resins contained in the magnetic layer include conventionally known thermoplastic resins, thermosetting resins, ultraviolet-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-based elastomers, olefin-based elastomers, vinyl chloride-based elastomers, polyester-based elastomers, polyamide-based elastomers, polyurethane-based elastomers, and acrylic elastomers. In the present invention and this specification, the term "urethane resin" is used as a general term for resins containing urethane bonds.

[0022] In addition to the above components, the magnetic layer may also contain any amount of one or more known additives such as a curing agent, a curing accelerator, a dispersant, a stabilizer, a crosslinking agent (for example, a coupling agent), and the like.

[0023] The curing agent can improve the strength and durability of the magnetic layer. Examples of curing agents contained in the magnetic layer include thermosetting resins, photocurable resins (e.g., ultraviolet-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.

[0024] Examples of isocyanates include aliphatic polyisocyanates, aromatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates. Specific examples of aliphatic polyisocyanates include HDI (hexamethylene diisocyanate), an adduct of HDI with TMP (trimethylolpropane), a biuret of HDI, and an isocyanurate of HDI. Specific examples of aromatic polyisocyanates include TDI (tolylene diisocyanate), an adduct of TDI with a polyol compound (e.g., a TMP adduct of TDI), a biuret of TDI, and an isocyanurate of TDI. Specific examples of aromatic aliphatic polyisocyanates include XDI (xylylene diisocyanate), a TMP adduct of XDI, a biuret of XDI, an isocyanurate of XDI, etc. Specific examples of alicyclic polyisocyanates include IPDI (isophorone diisocyanate), a TMP adduct of IPDI, a biuret of IPDI, an isocyanurate of IPDI, etc.

[0025] Examples of epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, bisphenol AF epoxy resins, dicyclopentadiene epoxy resins, trisphenol epoxy resins, naphthol novolac epoxy resins, phenol novolac epoxy resins, tert-butyl-catechol epoxy resins, naphthalene epoxy resins, naphthol epoxy resins, anthracene epoxy resins, glycidylamine epoxy resins, glycidyl ester epoxy resins, cresol novolac epoxy resins, biphenyl epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexanedimethanol epoxy resins, naphthylene ether epoxy resins, and trimethylol epoxy resins. These epoxy resins may be used alone or in combination of two or more in any proportion. A composition containing an epoxy resin can be cured by heating the epoxy groups contained in the epoxy resin to open their rings and form crosslinked structures. In a magnetic layer formed by curing a composition containing an epoxy resin, some or all of the epoxy groups contained in the epoxy resin may be contained in a state in which they have opened their rings and formed crosslinked structures.

[0026] Examples of the reaction catalyst include imidazoles, sulfonic acids, DBU (1,8-diazabicyclo[5.4.0]-7-undecene) salts, amines, heavy metals, acids, and cyclic ethers.

[0027] For example, a magnetic layer formed using a magnetic layer-forming composition containing a urethane resin, an epoxy resin, and an isocyanate can contain a urethane resin and a resin having a partial structure represented by the following formula 1. In formula 1, * represents the bonding position between adjacent atoms.

[0028]

[0029] The partial structure represented by formula 1 is an amino group derived from an isocyanate group of an isocyanate (for example, an isocyanate group and H ２O) with the epoxy groups of the epoxy resin. In the magnetic layer, the resin having the partial structure represented by formula 1 and the urethane resin may or may not be crosslinked by a curing agent or the like. This also applies to the urethane resin and the resin having one or more partial structures selected from the group consisting of the partial structure represented by formula 1-1, the partial structure represented by formula 1-2, and the partial structure represented by formula 1-3.

[0030] In one embodiment, a magnetic layer formed using a magnetic layer-forming composition containing a urethane resin, an epoxy resin, and an isocyanate can include a urethane resin and a resin having one or more partial structures selected from the group consisting of a partial structure represented by the following formula 1-1, a partial structure represented by the following formula 1-2, and a partial structure represented by the following formula 1-3. In formulas 1-1, 1-2, and 1-3, * represents the bonding position with adjacent atoms. The partial structures represented by each of formulas 1-1, 1-2, and 1-3 include the partial structure represented by formula 1. In another embodiment, the resin included in the magnetic layer can be a resin that has the partial structure represented by formula 1, but does not have the partial structure represented by formula 1-1, the partial structure represented by formula 1-2, or the partial structure represented by formula 1-3.

[0031]

[0032] For example, a magnetic layer formed using a magnetic layer-forming composition containing a urethane resin, an epoxy resin, and HDI can include a urethane resin and a resin having a partial structure represented by the following formula 1-1. A magnetic layer formed using a magnetic layer-forming composition containing a urethane resin, an epoxy resin, and IPDI can include a urethane resin and a resin having a partial structure represented by the following formula 1-2 and / or a partial structure represented by the following formula 1-3.

[0033] From the viewpoints of improving adhesion between the magnetic layer and adjacent layers and improving the strength of the magnetic layer, it is preferable that the magnetic layer contain a urethane resin and a resin having a partial structure represented by Formula 1. From these viewpoints, it is more preferable that the magnetic layer contain a urethane resin and a resin having one or more partial structures selected from the group consisting of Formula 1-1, Formula 1-2, and Formula 1-3.

[0034] Whether the urethane resin and the resin having the partial structure described above are contained in the magnetic layer can be confirmed by known methods.

[0035] When the electromagnetic wave shielding material includes only one magnetic layer, the thickness of this magnetic layer can be, for example, 5 μm or more. From the viewpoint of further improving the shielding ability of the electromagnetic wave shielding material, it is preferably 10 μm or more, and more preferably 20 μm or more. On the other hand, the thickness of this magnetic layer can be, for example, 100 μm or less or 90 μm or less. From the viewpoint of improving moldability, it is preferably less than 90 μm, more preferably 80 μm or less, and even more preferably 70 μm or less. When the electromagnetic wave shielding material includes 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. From the viewpoint of further improving the shielding ability of the electromagnetic wave shielding material, it is preferably 10 μm or more, and more preferably 20 μm or more. On the other hand, this magnetic layer can be, for example, 100 μm or less or 90 μm or less. From the viewpoint of improving moldability, it is preferably less than 90 μm, and more preferably 80 μm or less. The thicknesses of the two or more magnetic layers can be the same or different. When the electromagnetic wave shielding material includes only one magnetic layer, this one magnetic layer is a magnetic layer sandwiched between two metal layers. When the electromagnetic wave shielding material includes two or more magnetic layers, at least one magnetic layer can be a magnetic layer sandwiched between two metal layers, and some or all of the two or more magnetic layers can each be a magnetic layer sandwiched between two metal layers. Specific examples of the layer structure of the electromagnetic wave shielding material will be described later.

[0036] <Metal Layer> The electromagnetic shielding material has a multilayer structure in which a magnetic layer is sandwiched between two metal layers. The electromagnetic shielding material may include one or more such multilayer structures, and may also include two or more. That is, the electromagnetic shielding material may include at least two metal layers, and may also include three or more metal layers, or may include at least one magnetic layer, and may also include two or more magnetic layers. In one embodiment, the two or more metal layers included in the electromagnetic shielding material have the same composition and thickness, and in another embodiment, they have different compositions and / or thicknesses. This is true when the electromagnetic shielding material includes two or more magnetic layers, and also when the electromagnetic shielding material includes two or more other layers, such as a resin-containing layer, as described below.

[0037] In the present invention and this specification, the term "metal layer" refers to a layer containing a metal. The metal layer may be a layer containing one or more metals 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 non-metal elements.

[0038] The metal layer included in the electromagnetic wave shielding material can be a layer containing one or more metals selected from the group consisting of various pure metals and various alloys. The metal layer can exhibit an attenuation effect in the shielding material. This is preferable from the perspective of improving the shielding ability of the electromagnetic wave shielding material. The attenuation effect is greater with a larger propagation constant, and the propagation constant is greater with a higher electrical conductivity. Therefore, it is preferable that the metal layer contain a metal element with high electrical conductivity. From this perspective, it is preferable that the metal layer contain a pure metal such as Ag, Cu, Au, or Al, or an alloy containing any of these as a 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 higher is called a pure metal. Purity is measured by mass. An alloy is generally a pure metal with a composition adjusted by adding one or more metal or non-metallic elements to a pure metal for corrosion prevention, strength improvement, etc. The main component of 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 (e.g., 99.8% by mass or less) in the alloy. From the viewpoint of economy, pure metals of Cu or Al or alloys containing Cu or Al as a main component are preferred.

[0039] In one embodiment, 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 by mass unless otherwise specified. For example, the metal layer can be a pure metal or alloy processed into a sheet. For example, a commercially available metal foil or a metal foil prepared by a known method can be used as the metal layer. Pure Cu metal sheets (so-called copper foils) of various thicknesses are commercially available. For example, such copper foils can be used as the metal layer. Copper foils include electrolytic copper foils obtained by electroplating copper foils on a cathode, and rolled copper foils obtained by thinly rolling an ingot under heat and pressure. Both copper foils can be used as the metal layer of the electromagnetic wave shielding material. Furthermore, Al sheets (so-called aluminum foils) of various thicknesses are commercially available. For example, such aluminum foils can be used as the metal layer.

[0040] From the perspective of reducing the weight of the electromagnetic wave shielding material, it is preferable that one or both (preferably both) of the two metal layers sandwiching the magnetic layer be 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 its 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 its 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, or may contain Al and Mg. Both Al and Mg have a small value obtained by dividing the specific gravity by the electrical conductivity (specific gravity / electrical conductivity). The smaller this value, the lighter the electromagnetic wave shielding material that exhibits high shielding ability can be. For example, the value obtained by dividing the specific gravity by the electrical conductivity of Cu, Al, and Mg (specific gravity / electrical conductivity) calculated from literature values ​​is 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. In one embodiment, the metal layer containing a metal selected from the group consisting of Al and Mg can contain only one of Al and Mg, and in another embodiment, it can contain both. From the viewpoint of reducing the weight of the electromagnetic shielding material, it is more preferable that one or both (preferably both) of the two metal layers sandwiching the magnetic layer be a metal layer having a metal content selected from the group consisting of Al and Mg of 80.0% by mass or more, and even more preferable that the metal content selected from the group consisting of Al and Mg be a metal layer having a metal content selected from the group consisting of Al and Mg of 90.0% by mass or more. Of Al and Mg, the metal layer containing at least Al can be a metal layer having an Al content of 80.0% by mass or more, or can also be a metal layer having an Al content of 90.0% by mass or more. Of Al and Mg, the metal layer containing at least Mg can be a metal layer having an Mg content of 80.0% by mass or more, or can also be a metal layer having an Mg content of 90.0% by 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 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 expressed as a percentage relative to the total mass of the metal layer.

[0041] From one or more of the viewpoints of economy, high electrical conductivity, and weight reduction of the electromagnetic wave shielding material, it is preferable that one or both (preferably both) of the two metal layers sandwiching the magnetic layer be 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 a primary component. In a layer containing a metal selected from the group consisting of Al, Mg, and Cu as a primary component, Al, Mg, or Cu is the component with the highest proportion by mass in this layer. Such a layer may contain only one, two, or three metals selected from Al, Mg, and Cu. From one or more of the above viewpoints, it is more preferable that one or both (preferably both) of the two metal layers sandwiching the magnetic layer be a metal layer containing 80.0% by mass or more of a metal selected from the group consisting of Al, Mg, and Cu, and even more preferably a metal layer containing 90.0% by mass or more of a metal selected from the group consisting of Al, Mg, and Cu. A metal layer containing at least Al among Al, Mg, and Cu can be a metal layer with an Al content of 80.0 mass% or more, or can be a metal layer with an Al content of 90.0 mass% or more. A metal layer containing at least Mg among Al, Mg, and Cu can be a metal layer with an Mg content of 80.0 mass% or more, or can be a metal layer with an Mg content of 90.0 mass% or more. A metal layer containing at least Cu among Al, Mg, and Cu can be a metal layer with a Cu content of 80.0 mass% or more, or can be a metal layer with a Cu content of 90.0 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 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 expressed as a percentage relative to the total mass of the metal layer.

[0042] With respect to the thickness of the metal layer, from the viewpoint of further improving the processability of the metal layer and the shielding ability of the electromagnetic wave shielding material, the thickness per layer is preferably 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, the thickness per layer is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less.

[0043] <Resin-containing layer> The electromagnetic wave shielding material has one or more magnetic layers sandwiched between two metal layers, and further has resin-containing layers on both sides of at least one of the two metal layers, and the difference in thickness between the resin-containing layers on both sides of the metal layer is 20 μm or less.

[0044] In the present invention and this specification, a "resin-containing layer" refers to a layer containing one or more resins. In one embodiment, the resin-containing layer can have a single-layer structure, and in another embodiment, it has a laminate structure of two or more resin-containing layers with different compositions and / or thicknesses. For a resin-containing layer having a laminate structure, the "thickness of the resin-containing layer" refers to the thickness of the laminate structure. The resin-containing layers located on both sides of the metal layer may have the same composition, layer structure, etc., or may be different.

[0045] In one embodiment of the electromagnetic wave shielding material, a resin-containing layer is included on both sides of only one of the two metal layers sandwiching the magnetic layer. In this embodiment, the difference in thickness between these two resin-containing layers is 20 μm or less. The thickness difference can be, for example, 18 μm or less, 16 μm or less, 14 μm or less, 12 μm or less, or 10 μm or less. The thickness difference can also be 0 μm or more, 1 μm or more, or 2 μm or more. When the thickness difference is 0 μm, the two resin-containing layers have the same thickness. In another embodiment, a resin-containing layer is included on both sides of each of the two metal layers sandwiching the magnetic layer. From the perspective of inhibiting corrosion of the metal layers, it is preferable to have a resin-containing layer on both sides of each of the two metal layers. In this embodiment, the difference in thickness between the resin-containing layers on both sides of at least one metal layer is 20 μm or less, for example, 18 μm or less, 16 μm or less, 14 μm or less, 12 μm or less, or 10 μm or less. The difference in thickness between the resin-containing layers located on both sides of the other metal layer is 20 μm or less or more than 20 μm, preferably 20 μm or less, and may be, for example, 18 μm or less, 16 μm or less, 14 μm or less, 12 μm or less, or 10 μm or less. The difference in thickness may also be 0 μm or more, 1 μm or more, or 2 μm or more.

[0046] The total thickness of the two resin-containing layers located on both sides of the metal layer can be, for example, 10 μm or more. From the viewpoint of improving the elongation of the electromagnetic wave shielding material, it is preferably 30 μm or more, and more preferably 40 μm or more, 50 μm or more, 60 μm or more, and 70 μm or more in that order. The total thickness of the two resin-containing layers can be, for example, 150 μm or less, 140 μm or less, 120 μm or less, or less than 100 μm. In the electromagnetic wave shielding material, when a resin-containing layer is included on both sides of each of the two metal layers sandwiching the magnetic layer, it is preferable that the total thickness of the two resin-containing layers located on both sides of one metal layer is within the above range, and the total thickness of the two resin-containing layers located on both sides of the other metal layer can be outside or within the above range, but is preferably within the above range.

[0047] The total thickness of the resin-containing layers included in the electromagnetic shielding material can be, for example, 180 μm or less, and from the viewpoint of shortening the burning time after the electromagnetic shielding material comes into contact with a flame, it is preferably less than 100 μm, more preferably 90 μm or less, and even more preferably 80 μm or less. The total thickness of the resin-containing layers included in the electromagnetic shielding material can be, for example, 10 μm or more, 15 μm or more, or 20 μm or more.

[0048] The thickness of one resin-containing layer included in the electromagnetic wave shielding material (the thickness of the laminate structure in the case of a laminate structure) can be, for example, 1 μm or more and 60 μm or less, although it is not limited to the range exemplified here.

[0049] At least one, preferably both, of the resin-containing layers located on both sides of the metal layer can be adjacent to the metal layer. In the present invention and this specification, "adjacent" means directly contacting without any other layer in between. In addition, the resin-containing layer adjacent to the metal layer can be adjacent to the magnetic layer on the surface opposite to the surface adjacent to the metal layer. Specific examples of the layer structure of the electromagnetic wave shielding material will be described later.

[0050] A specific form of the resin-containing layer will be described below.

[0051] (Adhesive Layer) One form of the resin-containing layer is an adhesive layer. In the present invention and this specification, the term "adhesive layer" refers to a layer that has tackiness on its surface at room temperature. With regard to tackiness, "room temperature" refers to 23°C. Such a layer adheres to an adherend due to its adhesive force when it comes into contact with the adherend. Tackiness generally refers to the property of exhibiting adhesive strength in a short time after contact with the adherend with very light force. In the present invention and this specification, the term "having tackiness" refers to a result of No. 1 to No. 32 in the inclined ball tack test (measurement environment: temperature 23°C, relative humidity 50%) specified in JIS Z 0237:2009. When another layer is laminated on the surface of the adhesive layer, for example, the other layer can be peeled off and the exposed adhesive layer surface can be subjected to the above test. When another layer is laminated on both one surface and the other surface of the adhesive layer, the other layer on either surface may be peeled off.

[0052] The adhesive layer can be formed 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 and processing it into a film. The adhesive layer-forming composition can be applied, for example, to a support. Coating can be performed using a known coating device such as a blade coater or a die coater. Coating can be performed using a so-called roll-to-roll method or a batch method. Examples of supports to which the adhesive layer-forming composition is applied include films made of various resins such as polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylics such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimides. Supports whose surfaces (coated surfaces) to which the adhesive layer-forming composition is applied (the surfaces to be coated) have been subjected to a release treatment by a known method can be used. 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. 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. An adhesive layer can be formed by applying an adhesive layer-forming composition, in which an adhesive is dissolved and / or dispersed in a solvent, to the surface to be coated and drying the composition. Alternatively, an adhesive tape including an adhesive layer can be used. Examples of the adhesive tape include double-sided tape. Double-sided tape has adhesive layers on both sides of the support. Alternatively, an adhesive tape having an adhesive layer on one side of the support can be used. Examples of the support include films, nonwoven fabrics, and paper made of various resins such as polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polycarbonate (PC), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide.As the adhesive tape having an adhesive layer on one or both sides of a support, a commercially available product can be used, and an adhesive tape produced by a known method can also be used.

[0053] The thickness of the adhesive layer is not particularly limited, and the thickness per layer can be, for example, 1 μm or more and 30 μm or less.

[0054] (Adhesive Layer) One form of the resin-containing layer is an adhesive layer. In the present invention and this specification, an "adhesive layer" refers to a layer in which a liquid or gel adhesive contacts an adherend and solidifies through a process of drying, curing, or other state changes, thereby exerting adhesion to the adherend through an anchoring effect, physical interaction, or the formation of a chemical bond. In one form, the adhesive layer may be a layer with no tackiness at room temperature. In another form, the adhesive layer is adjacent to a magnetic layer or a metal layer and can firmly adhere the magnetic layer or metal layer to the resin-containing layer. The adhesive includes 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 themselves be liquid or gel-like. Alternatively, a solid resin may be dissolved in a solvent to become liquid or gel-like. Examples of solvents contained in adhesives include ketone-based solvents such as water, acetone, methyl ethyl ketone, and cyclohexanone; acetate-based 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-based solvents such as toluene and xylene; amide-based solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; alcohol-based solvents such as ethanol, methanol, and propanol; and halogen-based solvents such as dichloromethane, trichloroethylene, and dichlorofluoroethane. The adhesive may contain a monomer that chemically reacts with the adherend to produce a resin. Examples of such monomers include epoxy monomers, isocyanates, polyols, polyphenols, acid anhydrides, acrylic esters, methacrylic esters, styrene monomers, and allyl monomers. The monomer contains one or more functional groups that undergo a chemical reaction. When a monomer having three or more functional groups is used, a resin containing a three-dimensional molecular structure is produced after the chemical reaction, making it possible to form an adhesive layer with higher mechanical strength.

[0055] The thickness of the adhesive layer is not particularly limited, and the thickness per layer can be, for example, 1 μm or more and 30 μm or less.

[0056] (Coating Layer) One form of the resin-containing layer is a coating layer. In the present invention and this specification, a "coating layer" refers to a layer in which a liquid or gel-like coating agent solidifies after contact with an adherend through changes in state, such as drying and curing, and exhibits water repellency, oil repellency, chemical resistance, and abrasion resistance, thereby 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 form, the coating layer can be provided on the outermost surface of the electromagnetic wave shielding material. The coating agent includes 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 themselves be liquid or gel-like. Alternatively, a solid resin may be dissolved in a solvent to become liquid or gel-like. Examples of solvents contained in the coating agent include ketone-based solvents such as water, acetone, methyl ethyl ketone, and cyclohexanone; acetate ester-based 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-based solvents such as toluene and xylene; amide-based solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; alcohol-based solvents such as ethanol, methanol, and propanol; and halogen-based solvents such as dichloromethane, trichloroethylene, and dichlorofluoroethane.

[0057] The thickness of the coating layer is not particularly limited, and the thickness per layer can be, for example, 1 μm or more and 10 μm or less.

[0058] It is also possible to cover the edges of the electromagnetic wave shielding material with a coating agent, which can prevent moisture, oil, and chemicals from entering through the edges, as well as mechanical damage.

[0059] (Resin Layer) One form of the resin-containing layer can be a resin layer. In the present invention and this specification, the term "resin layer" refers to a resin film formed from a thermoplastic resin such as a synthetic resin in a film-like shape, and the resin film has a film-like structure by itself and is not tacky at room temperature. Examples of thermoplastic resins 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 polyolefins, triacetyl cellulose (TAC), and other various resins.

[0060] The thickness of each resin layer may be, for example, 10 μm or more or 12 μm or more, and more preferably, 250 μm or less, 200 μm or less, 150 μm or less, or 100 μm or less.

[0061] The resin-containing layer can consist of, for example, only one adhesive layer, pressure-sensitive adhesive layer, or resin layer. A resin-containing layer having a laminated structure can include one or more adhesive and / or pressure-sensitive adhesive layers and one or more resin layers. The resin layer can be bonded to a metal layer or a magnetic layer, for example, via a pressure-sensitive adhesive or adhesive layer. Furthermore, since the resin layer is a thermoplastic resin-containing layer, it softens when heated. When pressed against an adherend in a heated state, it flows and conforms to minute irregularities on the adherend surface, exerting adhesive strength through an anchoring effect. The adhesive state can then be maintained by cooling. Therefore, in one embodiment, the resin layer can be bonded to another layer without a pressure-sensitive adhesive or adhesive layer. Furthermore, a commercially available double-sided tape or a tape prepared by a known method can also be used as the resin-containing layer having a laminated structure.

[0062] In a resin-containing layer having a laminated structure including a resin layer, the thickness of the resin layer (the total thickness of the resin layers when multiple resin layers are included) relative to 100% of the thickness of this layer (i.e., the laminated structure) can be, for example, 60% or more, 70% or more, or 80% or more, or can 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.

[0063] In one embodiment, the resin-containing layer can include one or more flame-retardant layers. In the present invention and this specification, the term "flame-retardant layer" refers to a layer that meets one or more of the following criteria: A layer that meets the flame-retardant rating of UL94V-0 or UL94V-1 in the UL (Underwriter's Laboratories Inc.) 94 Standard (Tests for Flammability of Plastic Materials for Parts in Devices and Appliances). Generally, UL94V-0 is also referred to as "V-0," and UL94V-1 is also referred to as "V-1." A layer with a flame retardancy rating of VTM-0 or VTM-1 in the UL94 VTM test (vertical burn test for thin plastic films). The above-mentioned flame retardant layer is preferable because it has a short burning time after contact with a flame. A resin-containing layer including such a layer can shorten the burning time of an electromagnetic wave shielding material after contact with a flame. The resin-containing layer can consist of only a flame retardant layer, or can have a laminate structure including one or more flame retardant layers. In a resin-containing layer having a laminate structure including a flame retardant layer, the thickness of the flame retardant layer (the total thickness of multiple flame retardant layers when multiple flame retardant layers are included) relative to 100% of the thickness of this layer (i.e., the laminate structure) 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.

[0064] <Specific Example of Layer Configuration> The total number of magnetic layers included in the electromagnetic wave shielding material can be, for example, one to four. The electromagnetic wave shielding material includes one or more magnetic layers sandwiched between two metal layers, and can also include two or more such magnetic layers. It can also include four or fewer such magnetic layers. When the electromagnetic wave shielding material includes only one magnetic layer, this one magnetic layer is a magnetic layer sandwiched between two metal layers. When the electromagnetic wave shielding material includes two or more magnetic layers, at least one of these two or more magnetic layers is a magnetic layer sandwiched between two metal layers. More specifically, all or only some of the magnetic layers included in the electromagnetic wave shielding material are magnetic layers sandwiched between two metal layers.

[0065] The electromagnetic shielding material includes one or more magnetic layers sandwiched between two metal layers, and further includes resin-containing layers on both sides of at least one of the two metal layers. Therefore, the electromagnetic shielding material includes at least two resin-containing layers. The number of resin-containing layers included in the electromagnetic shielding material can be, for example, 10 or less, 8 or less, 6 or less, or 4 or less.

[0066] The following are examples of the arrangement of the "magnetic layer," "metal layer," and "resin-containing layer" in the electromagnetic wave shielding material. However, the layer configuration of the electromagnetic wave shielding material is not limited to the layer configuration exemplified below. In the following, the symbol " / " means that the layer on the left of the symbol and the layer on the right of the symbol are in direct contact (i.e., adjacent) with no other layer in between.

[0067] Example 1: Resin-containing layer 1 / Metal layer 1 / Resin-containing layer 2 / Magnetic layer 1 / Resin-containing layer 3 / Metal layer 2 / Resin-containing layer 4 Example 2: Resin-containing layer 1 / Metal layer 1 / Resin-containing layer 2 / Magnetic layer 1 / Resin-containing layer 3 / Metal layer 2 Example 3: Magnetic layer 1 / Resin-containing layer 1 / Metal layer 1 / Resin-containing layer 2 / Magnetic layer 2 / Resin-containing layer 3 / Metal layer 2 / Resin-containing layer 4 / Magnetic layer 3 Example 4: Resin-containing layer 1 / Metal layer 1 / Resin-containing layer 2 / Magnetic layer 1 / Resin-containing layer 3 / Metal layer 2 / Resin-containing layer 4 / Magnetic layer 2 / Resin-containing layer 5 / Metal layer 3 / Resin-containing layer 6

[0068] For example, in Example 1, the resin-containing layers located on both sides of metal layer 1 are resin-containing layer 1 and resin-containing layer 2. Magnetic layer 1 is a magnetic layer sandwiched between metal layer 1 and metal layer 2. The resin-containing layers located on both sides of metal layer 2 are resin-containing layer 3 and resin-containing layer 4. In Example 2, the resin-containing layers located on both sides of metal layer 1 are resin-containing layer 1 and resin-containing layer 2. Magnetic layer 1 is a magnetic layer sandwiched between metal layer 1 and metal layer 2. In Example 3, the resin-containing layers located on both sides of metal layer 1 are resin-containing layer 1 and resin-containing layer 2. Magnetic layer 2 is a magnetic layer sandwiched between metal layer 1 and metal layer 2. The resin-containing layers located on both sides of metal layer 2 are resin-containing layer 3 and resin-containing layer 4. In Example 4, the resin-containing layers located on both sides of metal layer 1 are resin-containing layer 1 and resin-containing layer 2. Magnetic layer 1 is a magnetic layer sandwiched between metal layer 1 and metal layer 2. The resin-containing layers located on both sides of metal layer 2 are resin-containing layer 3 and resin-containing layer 4. Magnetic layer 2 is a magnetic layer sandwiched between metal layer 2 and metal layer 3. In Example 4, metal layer 2 is one of the two metal layers sandwiching magnetic layer 1, and is also one of the two metal layers sandwiching magnetic layer 2. For example, as in Example 4, the metal layers sandwiching one magnetic layer can also be the metal layers sandwiching another magnetic layer.

[0069] In one embodiment, one or both of the outermost layers of the electromagnetic shielding material may be a resin-containing layer, which is preferable from the viewpoint of inhibiting corrosion of the outermost layer of the electromagnetic shielding material.

[0070] <Method for Manufacturing Electromagnetic Shielding Material> (Method for Forming Magnetic Layer) The magnetic layer can be prepared, for example, by applying a magnetic layer-forming composition and drying the resulting coating. The magnetic layer-forming composition can contain the components described above and can optionally contain one or more solvents. Examples of solvents include various organic solvents, such as ketone-based solvents such as acetone, methyl ethyl ketone, and cyclohexanone; acetate ester-based 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-based solvents such as toluene and xylene; and amide-based solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. A single solvent, or a mixture of two or more solvents in any ratio, can be selected based on the solubility of the components used in preparing the magnetic layer-forming composition. The solvent content of the magnetic layer-forming composition is not particularly limited and can be determined taking into account the coatability of the magnetic layer-forming composition.

[0071] The magnetic layer-forming composition can be prepared by mixing the various components sequentially in any order or simultaneously. If necessary, dispersion treatment can be carried out using a known dispersing machine such as a ball mill, bead mill, sand mill, or roll mill, and / or stirring treatment can be carried out using a known stirring machine such as a vibration stirring machine.

[0072] The magnetic layer-forming composition can be applied onto a support, for example. The application can be carried out using a known application device such as a blade coater or a die coater. The application can be carried out by a so-called roll-to-roll method or a batch method.

[0073] Examples of substrates onto which the magnetic layer-forming composition is applied include films of various resins, such as polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylics such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. For details of these resin films, see paragraphs 0081 to 0086 of JP 2015-187260 A. As the substrate, a substrate whose surface (the surface to be coated) onto which the magnetic layer-forming composition is applied has been subjected to a release treatment by a known method can be used. One form of release treatment is the formation of a release layer. For details of the release layer, see paragraph 0084 of JP 2015-187260 A. Alternatively, commercially available release-treated resin films can be used as the substrate. By using a substrate whose surface to be coated has been subjected to a release treatment, the magnetic layer and the substrate can be easily separated after film formation.

[0074] The magnetic layer-forming composition can also be applied to the surface of a metal layer, a resin-containing layer, or the like. For example, it is possible to prepare 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 then, if necessary, subjecting the magnetic layer to a pressure treatment as described below. As an example, a partial structure of "resin-containing layer / metal layer / resin-containing layer / magnetic layer" is prepared by applying a magnetic layer-forming coating liquid to the surface of the resin-containing layer of a laminate having a layer structure of "resin-containing layer / metal layer / resin-containing layer," and then, if necessary, subjecting the magnetic layer to a pressure treatment as described below. Two partial structures of "resin-containing layer / metal layer / resin-containing layer / magnetic layer" thus prepared are then pressed together with the magnetic layer sides facing each other by applying pressure and heat, thereby preparing an electromagnetic wave shielding material having the layer structure of Example 1 described above, "resin-containing layer 1 / metal layer 1 / resin-containing layer 2 / magnetic layer 1 / resin-containing layer 3 / metal layer 2 / resin-containing layer 4."

[0075] 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 can be carried out under conditions that allow the solvent contained in the magnetic layer-forming composition to volatilize. As an example, the drying can be carried out for 1 minute to 2 hours in a heated atmosphere at an ambient temperature of 80 to 150°C.

[0076] (Pressure Treatment of Magnetic Layer) The magnetic layer can also be pressure treated after deposition. By pressure treating the magnetic layer containing magnetic particles, the density of magnetic particles in the magnetic layer can be increased.

[0077] The pressure treatment can be carried out 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 arranged above and below, and the two press plates are brought together using mechanical or hydraulic pressure to apply pressure to the object to be pressed. A roll press passes the object to be pressed between rotating pressure rolls arranged above and below, and pressure can be applied by applying mechanical or hydraulic pressure to the pressure rolls or by making the distance between the pressure rolls smaller than the thickness of the object to be pressed.

[0078] The pressure during the pressure treatment can be set arbitrarily. For example, in the case of a flat press, the pressure is set to, for example, 1 to 50 N (Newton) / mm ２In the case of a roll press, the linear pressure is, for example, 20 to 400 N / mm. The pressing time can be set as desired. When a flat plate press is used, the time is, for example, 5 seconds to 30 minutes. When a roll press is used, the pressing time can be controlled by the conveying speed of the material to be pressed, for example, 10 cm / min to 200 m / min. The materials of the press plate and pressure roll can be selected from metal, ceramic, plastic, rubber, etc. During the pressing process, heat can be applied to both the upper and lower press plates or one of the press plates on a plate press, or to one of the upper and lower rolls of a roll press. Heating can soften the magnetic layer, thereby achieving a high compression effect when pressure is applied. The heating temperature can be set as desired, for example, from 50°C to 200°C. The heating temperature can be the internal temperature of the press plate or roll. This temperature can be measured using a thermometer installed inside the press plate or roll. After heating and pressurizing treatment in a plate-type press, the magnetic layer can be removed, for example, by separating the press plate while the temperature of the press plate is still high. Alternatively, the press plate can be cooled by water cooling, air cooling, or the like while maintaining the pressure, and then the press plate can be separated and the magnetic layer can be removed. In a roll press, the magnetic layer can be cooled by water cooling, air cooling, or the like immediately after pressing. It is also possible to repeat the pressure treatment two or more times. When the magnetic layer is formed on a release film, for example, the magnetic layer can be subjected to pressure treatment while laminated on the release film. Alternatively, the magnetic layer can be peeled off from the release film and subjected to pressure treatment as a single layer.

[0079] (Bonding of Various Layers) An adhesive layer or a bonding layer can be used to bond the various layers together. The adhesive layer and the bonding layer are as described above. In the electromagnetic wave shielding material, two adjacent layers can also be bonded together by applying pressure and heat, for example. A plate-type press, a roll press, or the like can be used for the bonding. For example, when a magnetic layer is disposed as a layer that is in direct contact with (i.e., adjacent to) an adjacent layer, the magnetic layer softens in the bonding step, promoting contact with the surface of the adjacent layer, thereby allowing the magnetic layer and the adjacent layer to be bonded together without any other layer interposed. The pressure during bonding can be set as desired. In the case of a plate-type press, for example, a pressure of 1 to 50 N (Newton) / mm ２ In the case of a roll press, the linear pressure is, for example, 20 to 400 N / mm. The pressure application time during compression can be set as desired. When a plate press is used, it is, for example, 5 seconds to 30 minutes. When a roll press is used, it can be controlled by the conveying speed of the material to be pressed, and the conveying speed is, for example, 10 cm / min to 200 m / min. The temperature during compression can be selected as desired, and is, for example, 20°C or higher and 200°C or lower. The temperature during compression can be, for example, the internal temperature of the press plate or roll.

[0080] The electromagnetic shielding material 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 the present invention and this specification, "sheet" is synonymous with "film." The electromagnetic shielding material can also be a three-dimensionally molded product obtained by three-dimensionally molding a sheet-like electromagnetic shielding material, or a sheet-like electromagnetic shielding material for three-dimensional molding. Various molding methods, such as mold press molding, vacuum molding, and pressure molding, can be used as three-dimensional molding methods. Regarding molding methods, molding performed without heating the object and / or mold, or by heating at a low temperature, is generally called cold molding. In one form, the electromagnetic shielding material can be molded by cold molding, such as drawing molding and stretch molding. Drawing molding is a molding method in which a sheet-like object is pressed using a pair of molds, consisting of a female mold and a male mold, to form a container with a bottom of various shapes, such as a cylinder, a rectangular tube, or a cone. In contrast, stretch forming is a method of forming a molded product with a curved surface extending from a flat surface from a sheet-like object. Stretch forming can also be performed using a press with only a male mold and no female mold. Drawing is broadly divided into deep drawing and shallow drawing. Shallow drawing forms a shallow molded product, while deep drawing forms a deep molded product (for example, a depth greater than the diameter of a cylinder or cone or the length of one side of a pyramid). Publicly known techniques can be applied to three-dimensional forming methods.

[0081] One aspect of the present invention relates to: an electromagnetic wave shielding material having a magnetic layer containing a urethane resin and a resin having a partial structure represented by Formula 1 shown above; and an electromagnetic wave shielding material having a magnetic layer containing a urethane resin and a resin having one or more partial structures selected from the group consisting of Formula 1-1, Formula 1-2, and Formula 1-3 shown above.

[0082] The electromagnetic shielding material of the above embodiment can be an electromagnetic shielding material consisting only of the magnetic layer. Alternatively, the electromagnetic shielding material of the above embodiment can be an electromagnetic shielding material having the magnetic layer between two resin-containing layers. In this case, each of the two resin-containing layers can be, for example, a layer adjacent to the magnetic layer. Alternatively, the two resin-containing layers can be, for example, the resin layers described above.

[0083] [Electronic Component] One aspect of the present invention relates to an electronic component comprising the electromagnetic wave shielding material. Examples of the electronic component include various electronic components such as electronic components contained in electronic devices such as mobile phones, personal digital assistants, and medical devices, as well as semiconductor elements, capacitors, coils, and cables. The electromagnetic wave shielding material can be three-dimensionally molded into any shape depending on the shape of the electronic component and placed inside the electronic component, or 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.

[0084] [Electronic Device] One aspect of the present invention relates to an electronic device including the electromagnetic shielding material. Examples of the electronic device include electronic devices such as mobile phones, personal digital assistants, and medical 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 can include the electromagnetic shielding material as a component of the electronic components included in the device. Furthermore, as a component of the electronic device, the electromagnetic shielding material can be disposed inside the electronic device, or can be disposed as a cover material that covers the outside of the electronic device. Alternatively, the electromagnetic shielding material can be three-dimensionally molded into a cylindrical shape and disposed as a cover material that covers the outside of a cable.

[0085] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the embodiments shown in the examples.

[0086] Example 1 Production of Resin-Containing Layer (Preparation of Adhesive Liquid) 32.5% by mass of base agent (TM-250HV manufactured by Toyo-Morton Co., Ltd.), 4.5% by mass of curing agent (CAT-RT86L-60 manufactured by Toyo-Morton Co., Ltd.), and 63% by mass of ethyl acetate were added to a plastic bottle and mixed for 1 hour using a shaking mixer to prepare an adhesive liquid.

[0087] (Coating of adhesive) An adhesive liquid was applied to one side of a flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation) that was VTM-0 in the UL94 VTM test using a blade coater with a coating gap of 50 μm, and the film was dried in a draft for 30 minutes, and then dried for 1 minute in a drying device with an internal atmospheric temperature of 100° C. In this way, a resin-containing layer having a laminated structure of a resin layer (flame-retardant PET film) and an adhesive layer was produced.

[0088] <Preparation of Metal Layer with Resin-Containing Layer> Two resin-containing layers were prepared by the above method. 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 with the adhesive layer facing upward, and another resin-containing layer was placed on top with the adhesive layer facing the metal layer side. The resulting "resin-containing layer / metal layer / resin-containing layer" laminate was sandwiched between two Teflon (registered trademark) sheets. The upper and lower press plates of a plate-type press (Mini Test Press, manufactured by Toyo Seiki Co., Ltd.) were heated to 140°C (internal temperature of the press plates), and the laminate was pressed with a pressure of 30 N / mm ２ The upper and lower press plates were cooled to 50°C (internal temperature of the press plates) while maintaining the pressure, and then the metal layer with the resin-containing layer (a laminate having a layer structure of "resin-containing layer / metal layer / resin-containing layer") was removed from between the two Teflon (registered trademark) sheets.

[0089] <Preparation of Magnetic Layer-Forming Composition (Coating Liquid)> The following were added to a plastic bottle, and the mixture was mixed for 96 hours with a shaking stirrer to prepare a coating liquid (magnetic layer-forming composition): 100 g of Fe—Si—Al flat magnetic particles (Sendust MFS-SUH manufactured by MKT Corporation), 24.5 g of acrylic resin (Nipol acrylic rubber, product name, model number AR71, manufactured by Nippon Zeon Corporation), 0.5 g of crosslinking agent (silane coupling agent (product name: KBM-903), manufactured by Shin-Etsu Silicones Co., Ltd.), and 294 g of methyl ethyl ketone.

[0090] <Preparation of magnetic layer> (Formation of magnetic layer) A coating liquid was applied to the surface of one of the resin-containing layers of the metal layer with a resin-containing layer using a blade coater with a coating gap of 380 μm, and the coating was dried for 8 minutes in a drying device with an internal atmosphere temperature of 90°C to form a magnetic layer.

[0091] <Preparation of Electromagnetic Wave Shielding Material> Two metal layers with a resin-containing layer on which a magnetic layer was formed (laminates with a layer structure of "resin-containing layer / metal layer / resin-containing layer / magnetic layer") were prepared by the method described above. The two sheets were stacked with the magnetic layers facing each other and sandwiched between two Teflon (registered trademark) sheets. The upper and lower press plates of a plate-shaped press (Mini Test Press manufactured by Toyo Seiki Co., Ltd.) were heated to 140°C (internal temperature of the press plates), and the laminate was pressed against the metal layer with a pressure of 3 N / mm. ２ The pressure was applied and 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), and then the electromagnetic wave shielding material was removed from between the two Teflon (registered trademark) sheets. In the tables below, the flame-retardant PET film is referred to as "flame-retardant PET" and the aluminum foil is referred to as "aluminum."

[0092] <Measurement of Thickness of Each Layer> Cross-section processing to expose the cross section of the electromagnetic shielding material was performed using the following method. The electromagnetic shielding material cut into 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 (IM4000PLUS, manufactured by Hitachi High-Technologies Corporation). The cross section of the exposed electromagnetic shielding material was observed using a scanning electron microscope (SU8220, manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 2 kV and a magnification of 100x to obtain a backscattered electron image. Using the scale bar as a reference, the thickness of five randomly selected points on each layer was measured from the obtained image, and the arithmetic mean of these measurements was taken as the thickness of each layer. In the tables below, the thickness of each layer is shown in parentheses in the "Layer Structure" and "Details of Layer Structure" columns.

[0093] <Thermal Shock Test> The following test was conducted in accordance with JIS C 60068-2-14:2011 Test Na standard. The electromagnetic shielding material was cut into a size of 15 cm x 15 cm and placed in an air-chamber thermal shock tester (TSA-203ES-W, manufactured by Espec Corporation). The material was stored in a temperature environment consisting of 5 cycles: 3 hours at -40°C on the low side and 3 hours at +125°C on the high side, with a temperature recovery time of 18 minutes or less. After storage, the electromagnetic shielding material was removed from the tester and its appearance was visually inspected. (Evaluation Criteria) A: No interlayer and / or intralayer peeling was observed. B: Interlayer and / or intralayer peeling was observed.

[0094] <Salt Spray Test> The test was conducted in accordance with JIS Z 7227:1998 under the following conditions. A spray liquid was sprayed onto one surface of the electromagnetic wave shielding material. After the test, the sample was washed with water and allowed to dry naturally, and then the appearance was visually observed. (Test Conditions) Spray liquid: 50±5 g / L NaCl aqueous solution, pH 6.5 to 7.2 Spray volume: 80 cm ２ 1.5±0.5mL / h per hour, Temperature inside the test chamber: 35±2°C, Arrangement angle: 20 degrees inclined from the vertical, Test time: 168 hours. (Evaluation criteria) A: No difference was observed in the appearance of the surface onto which the spray liquid was sprayed (hereinafter referred to as the "sprayed surface") before and after the test. B: A significant difference was observed in the appearance of the sprayed surface after the test compared to before the test.

[0095] <Flammability test> The following test was carried out in accordance with the UL94V standard. Five pieces of the electromagnetic shielding material were cut with a cutter knife to a length of 125 mm and a width of 13 mm to prepare test pieces. Each test piece was clamped and fixed vertically, and a burner with a flame size adjusted to 20 mm was applied to the edge for 10 seconds to observe the state of combustion of the sample. The test results were classified according to the flammability classification shown in the table below, and evaluated according to the following evaluation criteria. For evaluation result A, the flammability classification is shown in parentheses in the flammability test column in the table below. (Evaluation criteria) A: Flammability classification is V-0 or V-1 B: Flammability classification is V-2 C: Burning occurred up to the clamp

[0096]

[0097] <Tensile Test> The following test was carried out in accordance with JIS K 7127:1999. Five samples were prepared by punching out the electromagnetic wave shielding material into a dumbbell shape according to JIS K 7127 Type 5, and fixed to a universal testing machine (Instron 68FM-300) with a chuck distance of 80 mm. The test environment was 23°C ± 2°C, relative humidity 50% ± 10%, test speed 50 mm / min, and elongation was measured using a high-performance video extensometer (Instron AVE2) with a gauge length of 25 mm. The breaking strain was determined from the elongation at break. The determined breaking elongation value was evaluated according to the following evaluation criteria. (Evaluation Criteria) A: Breaking elongation is 40% or more B: Breaking elongation is less than 40%

[0098] Example 2 One of the resin-containing layers laminated to the metal layer was prepared using a PET film (Lumirror #38-S10 manufactured by Toray Industries, Inc.) instead of a flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation), and a magnetic layer was formed on the side of the resin-containing layer having the PET film (Lumirror #38-S10 manufactured by Toray Industries, Inc.). Except for the above points, the preparation of an electromagnetic wave shielding material and various evaluations were carried out using the same method as described for Example 1. In the tables below, "PET film" is abbreviated as "PET".

[0099] Example 3 One of the resin-containing layers to be laminated on the metal layer was prepared using a PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation), and a magnetic layer was formed on the side of the resin-containing layer having the PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.) Except for the above points, the electromagnetic wave shielding material was prepared and various evaluations were carried out by the same method as described for Example 1.

[0100] [Example 4] The resin-containing layers laminated on both sides of the metal layer were prepared using a PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). Except for the above points, the electromagnetic wave shielding material was prepared and various evaluations were carried out by the same method as described in Example 1.

[0101] Example 5 One of the resin-containing layers laminated onto the metal layer was prepared using a PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). The other resin-containing layer laminated onto the metal layer was prepared using a PET film (Lumirror #12-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation), and a magnetic layer was formed on the side of the resin-containing layer having the PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.). Except for the above points, the electromagnetic wave shielding material was prepared and various evaluations were carried out using the same method as described for Example 1.

[0102] Example 6 One of the resin-containing layers laminated onto the metal layer was prepared using a PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). The other resin-containing layer laminated onto the metal layer was prepared using a PET film (Lumirror #12-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation), and a magnetic layer was formed on the side of the resin-containing layer having the PET film (Lumirror #12-S10 manufactured by Toray Industries, Inc.). Except for the above points, the electromagnetic wave shielding material was prepared and various evaluations were carried out using the same method as described for Example 1.

[0103] [Example 7] The resin-containing layers laminated on both sides of the metal layer were prepared using a PET film (Lumirror #12-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). Except for the above points, the electromagnetic wave shielding material was prepared and various evaluations were carried out by the same method as described in Example 1.

[0104] Example 8 The resin-containing layer laminated onto one metal layer was prepared using a PET film (Lumirror #12-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). The resin-containing layer laminated onto the other metal layer was prepared using a PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). Except for the above points, the electromagnetic wave shielding material was prepared and various evaluations were carried out by the same method as described for Example 1.

[0105] Example 9 A resin-containing layer laminated on one metal layer was prepared using a PET film (Lumirror #50-S10 manufactured by Toray Industries, Inc.) instead of a flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). A magnetic layer was formed on the surface of one of the resin-containing layers of the metal layer with a resin-containing layer thus prepared (a laminate having a layer structure of "resin-containing layer / metal layer / resin-containing layer"). A magnetic layer was formed directly on one surface of the other metal layer. Except for the above points, the electromagnetic wave shielding material was prepared and various evaluations were performed using the method described for Example 1. A salt spray test was conducted using the surface of the metal layer on the side not laminated with the resin-containing layer as the sprayed surface.

[0106] Example 10 A resin-containing layer laminated on one metal layer was prepared using a PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.) instead of a flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). A magnetic layer was formed on the surface of one of the resin-containing layers of the metal layer with a resin-containing layer thus prepared (a laminate having a layer structure of "resin-containing layer / metal layer / resin-containing layer"). A magnetic layer was formed directly on one surface of the other metal layer. Except for the above points, the preparation and various evaluations of an electromagnetic wave shielding material were carried out using the method described for Example 1. A salt spray test was carried out using the surface of the metal layer on the side not laminated with the resin-containing layer as the sprayed surface.

[0107] Example 11: The resin-containing layer laminated on one metal layer was prepared using a PET film (Lumirror #12-S10 manufactured by Toray Industries, Inc.) and a PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.) instead of a flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). A magnetic layer was formed on the surface of the PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.) of the resin-containing layer-attached metal layer thus prepared (a laminate having a layer structure of "resin-containing layer / metal layer / resin-containing layer"). A magnetic layer was formed directly on one surface of the other metal layer. Except for the above points, the preparation and various evaluations of an electromagnetic wave shielding material were carried out using the method described for Example 1. A salt spray test was conducted using the surface of the metal layer on the side not laminated with the resin-containing layer as the sprayed surface.

[0108] Example 12 A resin-containing layer laminated on one metal layer was prepared using a PET film (Lumirror #12-S10 manufactured by Toray Industries, Inc.) instead of a flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). A magnetic layer was formed on the surface of one of the resin-containing layers of the metal layer with a resin-containing layer thus prepared (a laminate having a layer structure of "resin-containing layer / metal layer / resin-containing layer"). A magnetic layer was formed directly on one surface of the other metal layer. Except for the above points, the preparation and various evaluations of an electromagnetic wave shielding material were carried out using the method described for Example 1. A salt spray test was carried out using the surface of the metal layer on the side not laminated with the resin-containing layer as the sprayed surface.

[0109] [Example 13] <Preparation of magnetic layer> (Magnetic layer formation) The coating liquid (magnetic layer-forming composition) prepared by the method described in Example 1 was applied to the release surface of a release-treated PET film (PET75-LS2 manufactured by Nippa Corporation) using a blade coater with a coating gap of 650 μm, and dried for 8 minutes in a drying device with an internal atmosphere temperature of 90°C to form a magnetic layer.

[0110] (Pressure treatment of magnetic layer) The upper and lower press plates of a plate-shaped press (Mini Test Press manufactured by Toyo Seiki Seisakusho) were heated to 140°C (internal temperature of the press plates), and the magnetic layer from which the release-treated PET film had been peeled off was sandwiched between two 1 mm thick Teflon (registered trademark) sheets and subjected to a pressure of 3 N / mm. ２The pressure was maintained for 10 minutes under this condition. The upper and lower press plates were cooled to 50°C (internal temperature of the press plates) while maintaining the pressure, and then the magnetic layer was removed from between the two Teflon (registered trademark) sheets.

[0111] <Preparation of Electromagnetic Shielding Material> A magnetic layer and a metal layer (aluminum foil, model A1N30-O, manufactured by Takeuchi Metal Foil Powder Co., Ltd.) were bonded together using double-sided tape (NeoFix 5S2 manufactured by Nichiei Shinka Co., Ltd.). In this way, two laminates with a layer structure of "magnetic layer / double-sided tape / metal layer" were prepared. Separately, double-sided tape (NeoFix 5S2 manufactured by Nichiei Shinka Co., Ltd.) was bonded to the top and bottom surfaces of the magnetic layer to prepare one laminate with a layer structure of "double-sided tape / magnetic layer / double-sided tape". On both sides of the laminate with a layer structure of "double-sided tape / magnetic layer / double-sided tape", a laminate with a layer structure of "magnetic layer / double-sided tape / metal layer" was bonded, with the metal layer facing inward. The electromagnetic shielding material prepared in this way was evaluated using the method described for Example 1. In the tables below, "double-sided tape (NeoFix 5S2 manufactured by Nichiei Shinka Co., Ltd.)" is referred to as "Neofix 5S."

[0112] Comparative Example 1 A resin-containing layer was laminated on only one side of the metal layer, using a PET film (Lumirror #12-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation), and a magnetic layer was formed on the resin-containing layer side. Except for the above points, the electromagnetic wave shielding material was produced and various evaluations were carried out using the same method as described for Example 1. After a thermal shock test, peeling was observed at the interface between the magnetic layer and the adjacent layer.

[0113] Comparative Example 2 A resin-containing layer was laminated on only one side of the metal layer, using a PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation), and a magnetic layer was formed on the resin-containing layer side. Except for the above points, the electromagnetic wave shielding material was produced and various evaluations were carried out using the same method as described for Example 1. After a thermal shock test, peeling was observed at the interface between the magnetic layer and the adjacent layer.

[0114] Comparative Example 3 A resin-containing layer was laminated on only one side of the metal layer, using a PET film (Lumirror #50-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation), and a magnetic layer was formed on the resin-containing layer side. Except for the above points, the electromagnetic wave shielding material was produced and various evaluations were carried out using the same method as described for Example 1. After a thermal shock test, peeling was observed at the interface between the magnetic layer and the adjacent layer.

[0115] Comparative Example 4 One of the resin-containing layers laminated to the metal layer was prepared using a PET film (Lumirror #50-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation), and the other resin-containing layer was prepared using a PET film (Lumirror #12-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). A magnetic layer was formed on the resin-containing layer side having the PET film (Lumirror #12-S10 manufactured by Toray Industries, Inc.). Except for the above points, the electromagnetic wave shielding material was prepared and various evaluations were performed using the same method as in Example 1. After a thermal shock test, peeling was observed at the interface between the magnetic layer and the adjacent layer.

[0116] Comparative Example 5 One of the resin-containing layers laminated to the metal layer was prepared using a PET film (Lumirror #50-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation), and the other resin-containing layer was prepared using a PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.) instead of the flame-retardant PET film (Dialamy FR-02 manufactured by Mitsubishi Chemical Corporation). A magnetic layer was formed on the resin-containing layer side having the PET film (Lumirror #25-S10 manufactured by Toray Industries, Inc.). Except for the above points, the electromagnetic wave shielding material was prepared and various evaluations were performed using the same method as in Example 1. After a thermal shock test, peeling was observed at the interface between the magnetic layer and the adjacent layer.

[0117] Comparative Example 6 A magnetic layer was prepared using the method described for Example 13, and double-sided tape (NeoFix 5S2, manufactured by Nichiei Shinka Co., Ltd.) was attached to the top and bottom surfaces of the magnetic layer. Separately, two samples were prepared by attaching a PET film (Lumirror #50-S10, manufactured by Toray Industries, Inc.) to a metal layer (aluminum foil, model A1N30-O, manufactured by Takeuchi Metal Foil Powder Co., Ltd.) with double-sided tape (NeoFix 5S2, manufactured by Nichiei Shinka Co., Ltd.), and these were attached to the top and bottom surfaces of the magnetic layer with the metal layer facing the magnetic layer via the double-sided tape. The electromagnetic wave shielding material prepared in this manner was evaluated using the method described for Example 1.

[0118] The layer structures and various evaluation results of the electromagnetic wave shielding materials of the Examples and Comparative Examples are shown in the table below.

[0119]

[0120]

[0121] [Example 14] An electromagnetic wave shielding material was produced and various evaluations were carried out by the same method as described for Example 1, except that a magnetic layer-forming composition (coating liquid) was prepared as follows: The magnetic layer produced using the following coating liquid contains a urethane resin and a resin having a partial structure represented by Formula 1.

[0122] <Preparation of Magnetic Layer-Forming Composition (Coating Liquid)> The following were added to a plastic bottle and mixed for 1 hour using a shaking stirrer: 100 g of Fe—Si—Al flat-shaped magnetic particles (Sendust (trade name MFS-SUH) manufactured by MKT Corporation), 53.9 g of urethane resin (urethane resin solution (trade name Nipporan 5120) manufactured by Tosoh Corporation), 6.2 g of epoxy resin (modified epoxy resin (trade name HP-A-4860) manufactured by DIC Corporation), and 183.2 g of cyclohexanone. After mixing, the following were added: 2.4 g of curing agent (adduct of TDI and polyol compound (trade name Takenate D101E manufactured by Mitsui Chemicals, Inc.), and 0.2 g of curing accelerator (1-isobutyl-2-methylimidazole (trade name IBMI12) manufactured by Mitsubishi Chemical Corporation), and mixed for 10 minutes using a shaking stirrer to prepare a coating liquid (magnetic layer-forming composition).

[0123] Example 15 An electromagnetic wave shielding material was produced and various evaluations were carried out by the same method as described for Example 1, except that a magnetic layer-forming composition (coating liquid) was prepared as follows: The magnetic layer produced using the following coating liquid contains a urethane resin and a resin having a partial structure represented by Formula 1-1.

[0124] <Preparation of Magnetic Layer Forming Composition (Coating Liquid)> The following were added to a plastic bottle and mixed for 1 hour using a shaking mixer: 100 g of Fe—Si—Al flat magnetic particles (Sendust (trade name MFS-SUH) manufactured by MKT Corporation), 53.9 g of urethane resin (urethane resin solution (trade name Nipporan 5120) manufactured by Tosoh Corporation), 6.2 g of epoxy resin (modified epoxy resin (trade name HP-A-4860) manufactured by DIC Corporation), and 183.2 g of cyclohexanone. After mixing, the following was added: 2.4 g of curing agent (HDI (hexamethylene diisocyanate) (trade name Duranate TPA-100 manufactured by Asahi Kasei Corporation), and 0.2 g of curing accelerator (1-isobutyl-2-methylimidazole (trade name IBMI12) manufactured by Mitsubishi Chemical Corporation). The mixture was mixed for 10 minutes using a shaking stirrer to prepare a coating liquid (magnetic layer-forming composition).

[0125] The various evaluation results of the electromagnetic wave shielding materials of Examples 1 to 15 and Comparative Examples 1 to 6 are shown in the table below.

[0126]

[0127] [Testing the strength of the magnetic layer] <Preparation of magnetic layer sample for strength test> (Deposition of magnetic layer) The coating liquid (composition for forming the magnetic layer) prepared by the method described in Example 1 was applied to the release surface of a release-treated PET film (manufactured by Nippa Corporation, product name PET75x1-JOL) using a blade coater with a coating gap of 450 μm, and the coating liquid was dried for 8 minutes in a drying device with an internal atmosphere temperature of 90°C to form a magnetic layer.

[0128] (Pressing of magnetic layer for strength test) The magnetic layer formed by the above method was peeled from the release-treated PET film and placed on the release side of another release-treated PET film (manufactured by Nippa Corporation, product name PET100x1-LS2), and another release-treated PET film (manufactured by Nippa Corporation, product name PET100x1-LS2) was placed on top of the magnetic layer, with the release side facing the magnetic layer. The laminate thus produced, having a layer structure of "release-treated PET film / magnetic layer / release-treated PET film", was sandwiched between two Teflon (registered trademark) sheets. The upper and lower press plates of a plate-shaped 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 pressed at a pressure of 3 N / mm ２ The pressure was maintained for 10 minutes under this condition. The upper and lower press plates were cooled to 50°C (internal temperature of the press plates) while maintaining the pressure, and then the magnetic layer was removed from between the two Teflon (registered trademark) sheets and the release-treated PET film.

[0129] (Cutting out magnetic layer samples for strength tests) The magnetic layer removed above was cut out with a cutter into strips of 40 mm length x 10 mm width to provide magnetic layer samples for strength tests (reference sample 1-1).

[0130] A magnetic layer sample for strength testing (Reference Sample 1-14) was prepared in the same manner as described for Reference Sample 1-1, except that the coating liquid (magnetic layer-forming composition) prepared in the same manner as described for Example 14 was used.

[0131] A magnetic layer sample for strength testing (Reference Sample 1-15) was prepared in the same manner as described for Reference Sample 1-1, except that the coating liquid (magnetic layer-forming composition) prepared in the same manner as described for Example 15 was used.

[0132] <Measurement of Magnetic Layer Strength> The strength of each of Reference Sample 1-1, Reference Sample 1-14, and Reference Sample 1-15 was measured using the following method. The test environment was a temperature of 23°C ± 2°C and a relative humidity of 50% ± 10%. An Imada digital force gauge (product name: ZTS-100N) was attached to an Imada load measurement stand (product name: MX-2-500N), and an Imada film chuck (product name: FC-21) was attached to the load measurement stand and the digital force gauge. The distance between the tips of the two film chucks was 20 mm, and the sample was attached by clamping 10 mm of each end of the sample between the film chucks with the long side of the sample parallel to the tensile direction. The load measurement stand was raised at a speed of 10 mm / min, and the lift button on the load measurement stand was pressed continuously until the sample broke. The stress [N] measured during this process was recorded in a personal computer (PC) connected to the digital force gauge. The tensile strength [MPa] was calculated using the measured stress [N], the sample width of 10 mm, and the sample thickness [μm] using the following formula: Tensile strength [MPa] = - stress [N] / (10 [mm] × sample thickness [μm] / 1000) The maximum tensile strength value calculated for each sample is shown in the table below as the strength of that sample.

[0133]

[0134] [Peel Strength Test] <Preparation of Laminate Sample for Peel Strength Test> The magnetic layer formed on a release-treated PET film by the method previously described for Reference Sample 1-1 was peeled from the release-treated PET film and placed on a PET film (Lumirror #100-S10, manufactured by Toray Industries, Inc.), and another PET film (Lumirror #100-S10, manufactured by Toray Industries, Inc.) was placed on top of the magnetic layer. This laminate having a layer structure of "PET film / magnetic layer / PET film" was sandwiched between two Teflon (registered trademark) sheets. The upper and lower press plates of a plate-shaped 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 pressed at a pressure of 3 N / mm ２The pressure was applied and 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), and then the laminate having the layer structure of "PET film / magnetic layer / PET film" described above was removed from between the two Teflon (registered trademark) sheets. This laminate was used as a peel strength test sample (Reference Sample 2-1).

[0135] A peel strength test sample (Reference Sample 2-14) was prepared in the same manner as described for Reference Sample 2-1, except that the coating liquid (magnetic layer-forming composition) prepared in the same manner as described for Example 14 was used.

[0136] A peel strength test sample (Reference Sample 2-15) was prepared in the same manner as described for Reference Sample 2-1, except that the coating liquid (magnetic layer-forming composition) prepared in the same manner as described for Example 15 was used.

[0137] <Peel Strength Measurement> The peel strength of each of Reference Sample 2-1, Reference Sample 2-14, and Reference Sample 2-15 was measured using the following method. The higher the measured peel strength, the stronger the adhesion between the magnetic layer and the adjacent layer. Double-sided tape No. 5015 (manufactured by Nitto Denko Corporation), with the release tape on one side peeled along the length of the stainless steel plate, was attached to the center of the width of a 120 mm long, 40 mm wide, and 2 mm thick stainless steel plate. A soft urethane roller N010840 (manufactured by Ohta Manufacturing Co., Ltd.) was then rolled back and forth 10 times over the release film on the other side to apply force and secure the tape in place. The release film on the surface of the double-sided tape was peeled off, and a sample cut to a width of 10 mm and a length of 100 mm was placed on the tape. The soft urethane roller N010840 (manufactured by Ohta Manufacturing Co., Ltd.) was then rolled back and forth 10 times to apply force and secure the tape in place. After leaving the tape in air at room temperature for 48 hours, the tape was inserted into the magnetic layer of the sample (laminate) to create a 10 mm long peel area. The sample was attached to the standard stage of a peel tester VPA-H100F (Kyowa Interface Science Co., Ltd.). A 50 μm thick polyimide film 200H (Toray DuPont Co., Ltd.) was cut into a length of 100 mm and a width of 10 mm. One end of the polyimide film was bonded to the peeled portion of the shielding material via a 10 mm-long piece of double-sided tape No. 5015 (Nitto Denko Corporation). The other end of the polyimide film was attached to the grip of the measuring unit of the peel tester, and the peel force [N / cm] was measured at a peel angle of 90°, a peel rate of 20 mm / min, and a measurement distance of 60 mm. The average (arithmetic mean) of the measurement results from 20 mm to 50 mm in measurement distance was taken as the peel strength of the sample. Each sample was evaluated based on the determined peel strength value according to the following evaluation criteria. The evaluation results are shown in the table below. (Evaluation criteria) A: Peel strength is 3 N / mm or more B: Peel strength is 1 N / mm or more and less than 3 N / mm C: Peel strength is less than 1 N / mm

[0138]

[0139] The above sample was substituted for the shielding material of Example 1, Example 14, or Example 15, and a peel strength test was carried out by the above method. The obtained peel strength value was evaluated according to the above evaluation criteria. The evaluation results are shown in the table below.

[0140]

[0141] One aspect of the present invention is useful in the technical fields of various electronic components and various electronic devices.

Claims

1. An electromagnetic shielding material having one or more magnetic layers sandwiched between two metal layers, and further having resin-containing layers on both sides of at least one of the two metal layers, wherein the difference in thickness between the resin-containing layers on both sides of the metal layer is 20 μm or less.

2. The electromagnetic shielding material according to claim 1, wherein the total thickness of the resin-containing layers on both sides of the metal layer is 30 μm or more.

3. The electromagnetic shielding material according to claim 1, wherein the total thickness of the resin-containing layers included in the electromagnetic shielding material is less than 100 μm.

4. The electromagnetic shielding material according to claim 1, wherein at least one of the resin-containing layers on both sides of the metal layer contains one or more flame-retardant layers.

5. The electromagnetic shielding material according to claim 2, wherein the total thickness of the resin-containing layers contained in the electromagnetic shielding material is less than 100 μm, and at least one of the resin-containing layers on both sides of the metal layer contains one or more flame-retardant layers.

6. The electromagnetic shielding material according to claim 1, which has a resin-containing layer on both sides of each of the two metal layers.

7. The electromagnetic shielding material according to claim 6, wherein the difference in thickness between the resin-containing layers located on both sides of one of the two metal layers is 20 μm or less, and the difference in thickness between the resin-containing layers located on both sides of the other metal layer is 20 μm or less.

8. The electromagnetic shielding material according to claim 6, wherein the total thickness of the resin-containing layers located on both sides of one of the two metal layers is 30 μm or more, and the total thickness of the resin-containing layers located on both sides of the other metal layer is 30 μm or more.

9. The electromagnetic shielding material according to claim 6, wherein the total thickness of the resin-containing layers included in said electromagnetic shielding material is less than 100 μm.

10. The electromagnetic shielding material according to claim 6, wherein at least one of the resin-containing layers includes one or more flame-retardant layers.

11. The electromagnetic shielding material according to claim 7, wherein the total thickness of the resin-containing layers located on both sides of one of the two metal layers is 30 μm or more, and the total thickness of the resin-containing layers located on both sides of the other metal layer is 30 μm or more, the total thickness of the resin-containing layers included in the electromagnetic shielding material is less than 100 μm, and at least one of the resin-containing layers includes one or more flame-retardant layers.

12. The magnetic layer comprises a urethane resin and a compound represented by the following formula 1: The electromagnetic wave shielding material according to claim 1 , comprising: a resin having a partial structure represented by the following formula: (in formula 1, * represents a bonding position between adjacent atoms).

13. The magnetic layer comprises a urethane resin, a partial structure represented by the following formula 1-1, a partial structure represented by the following formula 1-2, and a partial structure represented by the following formula 1-3: (In formulas 1-1, 1-2, and 1-3, * represents a bonding position between adjacent atoms), and a resin having one or more partial structures selected from the group consisting of:

14. An electronic component comprising the electromagnetic shielding material according to any one of claims 1 to 13.

15. An electronic device comprising the electromagnetic shielding material according to any one of claims 1 to 13.

Images