Electromagnetic wave shielding material, electronic component, and electronic device

Abstract

The present invention provides: an electromagnetic wave shielding material which has a magnetic layer containing magnetic particles and an acrylic resin between two metal layers, wherein the degree of crosslinking of the magnetic layer is 20% or more, and the glass transition temperature Tg of the magnetic layer is -80°C or higher; an electronic component which includes the electromagnetic wave shielding material; and an electronic device.

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] Patent Document 1 discloses a resin composition containing a magnetic material, and describes that a member made using the resin composition can be used as an electromagnetic wave shielding film (see paragraph 0243 of Patent Document 1).

[0003] JP 2022-98300 A

[0004] 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. Electromagnetic wave shielding materials can exhibit electromagnetic wave shielding performance (hereinafter also referred to as "electromagnetic wave shielding ability" or "shielding ability") by reflecting and / or attenuating electromagnetic waves incident on the electromagnetic wave shielding material. For example, a member produced using the resin composition described in Patent Document 1 can function as an electromagnetic wave shielding material.

[0005] Electromagnetic shielding materials may be exposed to high temperatures when incorporated into electronic components or electronic devices. Therefore, it is desirable for electromagnetic shielding materials to be able to exhibit high shielding ability even after being exposed to high temperatures. Electromagnetic shielding materials that exhibit high shielding ability after being exposed to high temperatures can contribute to significantly reducing the effects of electromagnetic waves in electronic components and electronic devices even after being exposed to high temperatures. Hereinafter, exhibiting high shielding ability after being exposed to high temperatures is also referred to as having high heat resistance or excellent heat resistance.

[0006] In view of the above, an object of one aspect of the present invention is to provide an electromagnetic wave shielding material having excellent heat resistance.

[0007] One aspect of the present invention is as follows: [1] An electromagnetic wave shielding material having a magnetic layer containing magnetic particles and an acrylic resin between two metal layers, the magnetic layer having a degree of cross-linking of 20% or more, and the magnetic layer having a glass transition temperature Tg of -80°C or higher. [2] The electromagnetic wave shielding material according to [1], wherein the magnetic layer has a glass transition temperature Tg of -80°C or higher but lower than 5°C. [3] The magnetic layer is formed by mixing a compound represented by the following formula 1: In Formula 1, R １ , R ２ and R ３ each independently represent a hydrogen atom, an allyl group, an organic group containing a hydroxy group, an organic group containing a carboxy group, an organic group containing an alkoxysilyl group, or a glycidyl group. [4] The electromagnetic wave shielding material according to [3], wherein the magnetic layer has a glass transition temperature Tg of -80°C or higher and lower than 5°C. [5] The magnetic layer is formed from a compound represented by the following formula 2: In Formula 2, R ４ , R ５ and R ６each independently represent an amino group or an organic group containing an alkoxysilyl group. [6] The electromagnetic shielding material according to any one of [1] to [3], wherein the magnetic layer has a glass transition temperature Tg of -80°C or higher and lower than 5°C. [7] The electromagnetic shielding material according to any one of [1] to [6], wherein the magnetic layer contains an acrylic resin having an alkyl (meth)acrylate structure in which the alkyl group has 2 to 8 carbon atoms. [8] The electromagnetic shielding material according to any one of [1] to [7], wherein the magnetic layer contains an acrylic resin having an alkyl (meth)acrylate structure in which the alkyl group has 2 to 4 carbon atoms. [9] The electromagnetic shielding material according to any one of [1] to [8], wherein the magnetic layer has a degree of cross-linking of 20% to 98%.

[10] The electromagnetic shielding material according to any one of [1] to [9], wherein the magnetic layer has one or more layers containing a resin between the magnetic layer sandwiched between the two metal layers and one or both of the two metal layers.

[11] The electromagnetic wave shielding material according to any one of [1] to

[10] , wherein at least one of the metal layers has an Al content of 80.0% by mass or more.

[12] The electromagnetic wave shielding material according to any one of [1] to

[11] , wherein the magnetic layer has a glass transition temperature Tg of -40°C or more but less than -5°C.

[13] The electromagnetic wave shielding material according to any one of [1] to

[12] , wherein the magnetic layer contains an acrylic resin having an alkyl(meth)acrylate structure in which the alkyl group has 2 to 4 carbon atoms, the degree of crosslinking of the magnetic layer is 20% to 98%, at least one of the metal layers has an Al content of 80.0% by mass or more, and the glass transition temperature Tg of the magnetic layer is -40°C or more but less than -5°C.

[14] The electromagnetic wave shielding material according to

[13] , wherein at least one layer containing a resin is provided between the magnetic layer sandwiched between the two metal layers and one or both of the two metal layers.

[15] The magnetic layer has a structure represented by the following formula 1: In Formula 1, R １ , R ２ and R ３each independently represent a hydrogen atom, an allyl group, an organic group containing a hydroxyl group, an organic group containing a carboxyl group, an organic group containing an alkoxysilyl group, or a glycidyl group.

[16] The magnetic layer is an electromagnetic wave shielding material according to

[13] or

[14] , wherein In Formula 2, R ４ , R ５ and R ６ each independently represent an amino group or an organic group containing an alkoxysilyl group.

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

[16] .

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

[16] .

[0008] According to one aspect of the present invention, an electromagnetic wave shielding material having excellent heat resistance can be provided. Also, according to another aspect of the present invention, an electronic component and an electronic device including the electromagnetic wave shielding material can be provided.

[0009] 1 is an explanatory diagram relating to measurement of peel strength;

[0010] [Electromagnetic Wave Shielding Material] One aspect of the present invention relates to an electromagnetic wave shielding material having a magnetic layer containing magnetic particles and an acrylic resin between two metal layers, the magnetic layer having a degree of cross-linking of 20% or more and a glass transition temperature Tg of −80° C. or more.

[0011] 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.

[0012] In the present invention and this specification, the term "magnetic" means ferromagnetic property. The magnetic layer will be described in detail later.

[0013] The electromagnetic wave shielding material has a magnetic layer containing magnetic particles and an acrylic resin sandwiched between two metal layers. That is, the electromagnetic wave shielding material has a multilayer structure in which a magnetic layer is sandwiched between two metal layers. The inventors speculate that this multilayer structure may contribute to the electromagnetic wave shielding material's high shielding ability against electromagnetic waves. More specifically, to achieve high shielding ability against electromagnetic waves in an electromagnetic wave shielding material, it is desirable to enhance the electromagnetic wave attenuation capacity as well as increase reflection at the interface. That is, it is desirable for electromagnetic waves to be significantly attenuated by repeatedly reflecting at the interface and passing through the electromagnetic wave shielding material multiple times. However, in terms of the behavior of the metal layer and the magnetic layer with respect to electromagnetic waves, the metal layer has a high electromagnetic wave attenuation capacity but tends to reflect magnetic waves less at the interface, while the magnetic layer has a lower electromagnetic wave attenuation capacity than the metal layer but tends to reflect magnetic waves more at the interface than the metal layer. Therefore, it is difficult for a metal layer or a magnetic layer alone to achieve both high reflection and attenuation of magnetic waves, especially electromagnetic waves. In contrast, the electromagnetic wave shielding material has a multilayer structure in which a magnetic layer is sandwiched between two metal layers, thereby achieving both reflection at the interface and attenuation within the layers. The inventors believe this is the reason why the electromagnetic wave shielding material exhibits high shielding ability against electromagnetic waves, specifically against magnetic waves. Furthermore, the magnetic layer included in the multilayer structure contains an acrylic resin. Due to the carbon-carbon saturated bonds in the main chain, the main chain of the acrylic resin is thought to be resistant to thermal decomposition. The inventors believe that the inclusion of an acrylic resin in the magnetic layer contributes to the electromagnetic wave shielding material being able to exhibit high shielding ability without a significant decrease even after exposure to high temperatures. Additionally, the inventors believe that the cross-linking degree of the magnetic layer being 20% ​​or higher and the glass transition temperature Tg of the magnetic layer being −80°C or higher also contribute to the electromagnetic wave shielding material being able to exhibit high shielding ability without a significant decrease even after exposure to high temperatures.

[0014] Meanwhile, excellent formability is also a desirable property of an electromagnetic wave shielding material. Electromagnetic wave shielding materials can be molded into various shapes for incorporation into electronic components or electronic devices. An electromagnetic wave shielding material that is less likely to suffer from defects such as shape defects or breakage during molding can be said to have excellent formability. An electromagnetic wave shielding material with excellent formability is desirable in that it is less likely to cause breakage in molded products during three-dimensional molding (in other words, three-dimensional molding), for example. The glass transition temperature Tg of the magnetic layer is preferably less than 5°C. The inventors speculate that a glass transition temperature Tg of the magnetic layer of less than 5°C can contribute to the electromagnetic wave shielding material exhibiting excellent formability.

[0015] However, the present invention is not limited to the speculations set forth herein.

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

[0017] <Magnetic Layer> (Degree of Cross-Linking of Magnetic Layer) In the present invention and this specification, the degree of cross-linking of the magnetic layer is a value determined by the following method. The proportion of the binder component in the magnetic layer is determined by TG / DTA (Thermogram / Differential Thermal Analysis). "TG / DTA" is generally referred to as thermogravimetry / differential thermal analysis. Specifically, a measurement sample taken from the magnetic layer to be measured is measured using a TG / DTA (thermogravimetry / differential thermal analysis) device under conditions of a measurement temperature range of 23°C to 600°C and a heating rate of 10°C / min, and the percentage mass loss at 600°C is taken as the proportion of the binder component (unit: mass%). A measurement sample (70 mg) taken from the magnetic layer to be measured and 7 ml of tetrahydrofuran (THF) are added to a container whose empty mass has been measured, and the entire measurement sample is immersed in THF at room temperature for 12 hours. In this specification and the present invention, "room temperature" refers to 20 to 25°C. The contents of the container are then stirred for 30 minutes using a mix rotor at room temperature, after which the THF-insoluble components in the container are attracted to the bottom of the container with a magnet, and the supernatant is removed. 7 ml of acetone is then added to the container, and the contents are stirred for 30 minutes using a mix rotor at room temperature, after which the acetone-insoluble components in the container are attracted to the bottom of the container with a magnet, and the supernatant is removed. The container is then vacuum-dried for 1 hour in a vacuum dryer with an internal atmosphere temperature of 80°C, and the mass of the container is measured. The value obtained by subtracting the mass of the empty container from the measured mass is the mass of the solvent-insoluble components. The degree of crosslinking is calculated using the mass of the solvent-insoluble components thus obtained and the proportion (unit: mass%) of the binder components in the magnetic layer obtained by TG / DTA measurement, according to the following formula: Degree of crosslinking (%)=[1−{(mass of measurement sample (70 mg)−mass of solvent-insoluble component) / mass of binder component of measurement sample}]×100

[0018] In the electromagnetic wave shielding material, the degree of cross-linking of the magnetic layer sandwiched between two metal layers is 20% or more, preferably 30% or more, and more preferably 40% or more, 50% or more, and 60% or more, in that order, from the viewpoint of improving the heat resistance of the electromagnetic wave shielding material. The degree of cross-linking can be, for example, 100% or less, less than 100%, 98% or less, 96% or less, 93% or less, or 90% or less.

[0019] (Glass Transition Temperature Tg of Magnetic Layer) In the present invention and this specification, the glass transition temperature Tg of the magnetic layer is determined as the intermediate temperature between the start and end points of the decline on a DSC (Differential Scanning Calorimetry) chart from the results of heat flow measurement using a differential scanning calorimeter. Specific examples of the measurement method include the method described in the Examples section below.

[0020] In the electromagnetic shielding material, the glass transition temperature of the magnetic layer sandwiched between two metal layers is, from the viewpoint of improving the heat resistance of the electromagnetic shielding material, −80° C. or higher, preferably −70° C. or higher, and more preferably −60° C. or higher, −50° C. or higher, −40° C. or higher, −30° C. or higher, and −20° C. or higher in that order. On the other hand, from the viewpoint of improving formability, the glass transition temperature of the magnetic layer sandwiched between two metal layers in the electromagnetic shielding material is preferably less than 5° C., more preferably 0° C. or lower, even more preferably −5° C. or lower, even more preferably less than −5° C., and even more preferably −10° C. or lower.

[0021] (Magnetic Particles) The magnetic particles contained in the magnetic layer can be one type selected from the group consisting of magnetic particles generally called soft magnetic particles, such as metal particles and ferrite particles, or can be a combination of two or more types. 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 magnetic particles is considered to be a "magnetic layer."

[0022] Metal Particles Examples of metal particles serving as the magnetic particles 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 additives that may be added optionally 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.

[0023] In one embodiment, the electromagnetic wave shielding ability of an electromagnetic wave shielding material against electromagnetic waves can be evaluated using the magnetic permeability (more specifically, the real part of the complex relative magnetic permeability) of the magnetic layer included in the electromagnetic wave shielding material as an index. An electromagnetic wave shielding material having a magnetic layer exhibiting high magnetic permeability (more specifically, the real part of the complex relative magnetic permeability) is preferred because it can exhibit high shielding ability against electromagnetic waves.

[0024] When complex relative permeability is measured using a magnetic permeability measuring device, a real part μ' and an imaginary part μ" are usually displayed. In the present invention and this specification, the real part of complex relative permeability refers to this real part μ'. Hereinafter, the real part of complex relative permeability at a frequency of 3 MHz (megahertz) will also be referred to simply as "magnetic permeability" or "magnetic permeability μ'". Magnetic permeability can be measured using a commercially available magnetic permeability measuring device or a magnetic permeability measuring device with a known configuration. The measurement temperature is 25°C. By setting the ambient temperature around the measurement sample to the measurement temperature, temperature equilibrium is established, and the temperature of the measurement sample can be set to the measurement temperature. From the perspective of being able to exhibit even better electromagnetic wave shielding ability, the magnetic permeability (real part of complex relative permeability at a frequency of 3 MHz) of the magnetic layer contained in the electromagnetic wave shielding material is preferably 40 or more, and more preferably 100 or more, before and after thermal aging at 120°C, as determined by the method described in the Examples section below. The magnetic permeability may be, for example, 500 or less, 300 or less, or 200 or less, and may even exceed the values ​​exemplified here. Electromagnetic shielding materials with high magnetic permeability are preferred because they can exhibit excellent electromagnetic shielding ability.

[0025] From the viewpoint of forming a magnetic layer exhibiting high magnetic permeability, the magnetic particles are preferably particles having a flat shape (flat-shaped particles), and more preferably metal particles having a flat shape. By arranging the long side direction of the flat-shaped particles so that they are more parallel to the in-plane direction of the magnetic layer, the long side direction of the particles is more aligned with the vibration direction of the electromagnetic waves incident perpendicular to the electromagnetic wave shielding material, thereby reducing the demagnetizing field, and the magnetic layer can exhibit higher magnetic permeability. In the present invention and this specification, "flat-shaped particles" refers to particles having an aspect ratio of 0.200 or less. The aspect ratio of flat-shaped particles is preferably 0.150 or less, more preferably 0.100 or less. The aspect ratio of flat-shaped particles can be, for example, 0.010 or more, 0.020 or more, or 0.030 or more. For example, the particle shape can be made flat by flattening using a known method. For details on the flattening process, see, for example, the description in JP 2018-131640 A, including paragraphs 0016 and 0017 and the Examples therein. An example of a magnetic layer exhibiting high magnetic permeability is a magnetic layer containing flat particles of sendust.

[0026] As described above, from the viewpoint of forming a magnetic layer that exhibits high magnetic permeability, it is preferable to arrange the long side direction of the flat particles so that it is closer to parallel to the in-plane direction of the magnetic layer.From this point of view, the orientation degree, which is the sum of the absolute value of the average orientation angle of the flat particles relative to the surface of the magnetic layer and the variance of the orientation angle, is preferably 30° or less, more preferably 25° or less, even more preferably 20° or less, and even more preferably 15° or less.The orientation degree can be, for example, 3° or more, 5° or more, or 10° or more, and can also be lower than the values ​​exemplified here.The method for controlling the orientation degree will be described later.

[0027] In the present invention and this specification, the aspect ratio of the magnetic particles and the degree of orientation are determined by the following method. A cross section of the magnetic layer is exposed by a known method. A cross section image of a randomly selected region of this cross section is obtained as a scanning electron microscope (SEM) image. The imaging conditions are an acceleration voltage of 2 kV and a magnification of 1000x, and an SEM image is obtained as a backscattered electron image. The second argument is set to 0 using the cv2.imread() function of the image processing library OpenCV4 (manufactured by Intel Corporation), and the image is read in grayscale. A binarized image is obtained using the cv2.threshold() function, with the intermediate brightness between the high-brightness and low-brightness areas as the boundary. White areas (high-brightness areas) in the binarized image are identified as magnetic particles. The obtained binarized image is subjected to cv2.imread(). A rotated circumscribing rectangle corresponding to each magnetic particle portion is calculated using the minAreaRect() function, and the long side length, short side length, and rotation angle are calculated as the return values ​​of the cv2.minAreaRect() function. When calculating the total number of magnetic particles contained in the binarized image, particles in which only a portion of the particle is included in the binarized image are also included. For particles in which only a portion of the particle is included in the binarized image, the long side length, short side length, and rotation angle are calculated for the portion included in the binarized image. The ratio of the short side length to the long side length calculated in this manner (short side length / long side length) is used as the aspect ratio of each magnetic particle. In the present invention and this specification, if the number of magnetic particles identified as flat-shaped particles with an aspect ratio of 0.200 or less is 10% or more by number of the total number of magnetic particles contained in the binarized image, the magnetic layer is determined to be a "magnetic layer containing flat-shaped particles as magnetic particles." Furthermore, from the rotation angle determined above, the "orientation angle" is determined as the rotation angle relative to the horizontal plane (surface of the magnetic layer). Particles with an aspect ratio of 0.200 or less determined in the binarized image are identified as flat-shaped particles. The sum of the absolute value of the average value (arithmetic mean) and the variance of the orientation angles of all flat-shaped particles contained in the binarized image is determined. The sum thus determined is the "degree of orientation."The coordinates of the circumscribed rectangle are calculated using the cv2.boxPoints() function, and an image is created by overlaying the rotated circumscribed rectangle on the original image using the cv2.drawContours() function. Any rotated circumscribed rectangles that are clearly misdetected are excluded from the calculation of the aspect ratio and degree of orientation. The average value (arithmetic mean) of the aspect ratios of particles identified as flat-shaped particles is used as the aspect ratio of the flat-shaped particles contained in the magnetic layer to be measured. This aspect ratio is 0.200 or less, preferably 0.150 or less, and more preferably 0.100 or less. The aspect ratio can be, for example, 0.010 or more, 0.020 or more, or 0.030 or more.

[0028] The content of the magnetic particles in the magnetic layer can be, for example, 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, or 80 parts by weight or more, and can be, for example, 87 parts by weight or less, 85 parts by weight or less, 80 parts by weight or less, or 75 parts by weight or less, based on 100 parts by weight of the total weight of the magnetic layer. The magnetic layer can contain only one type of magnetic particle, or two or more types of magnetic particles in any ratio. In the present invention and this specification, when two or more types of a component are contained, the content refers to the total content of those components. The content of various components in the magnetic layer can be determined by known methods such as TG / DTA (Thermography / Differential Thermal Analysis) or extraction of various components using a solvent. If the composition of the magnetic layer-forming composition used to form the magnetic layer is known, the content of various components in the magnetic layer can also be determined from this known composition.

[0029] In one embodiment, the magnetic layer can be an insulating layer. In the present invention and this specification, "insulating" refers to an electrical conductivity of less than 1 S (Siemens) / m. The electrical conductivity of a certain layer is calculated from the surface electrical resistivity of the layer and the thickness of the layer using the following formula. Electrical conductivity can be measured using a known method. Electrical conductivity [S / m] = 1 / (surface electrical resistivity [Ω] × thickness [m])

[0030] The present inventors believe that the magnetic layer being an insulating layer is preferable for the electromagnetic wave shielding material to exhibit even higher electromagnetic wave shielding ability. From this point of view, the electrical conductivity of the magnetic layer is preferably less than 1 S / m, more preferably 0.5 S / m or less, even more preferably 0.1 S / m or less, and even more preferably 0.05 S / m or less. The electrical conductivity of the magnetic layer is, for example, 1.0×10 －１２ S / m or more or 1.0 x 10 －１０ It can be S / m or more.

[0031] (Acrylic Resin) In the present invention and this specification, a layer containing both magnetic particles and a resin is considered to be a "magnetic layer." The resin can function as a binder in the magnetic layer. Furthermore, at least a portion of the resin may be included in the magnetic layer in a state in which it forms a crosslinked structure with a crosslinking agent, as described in detail below. In the above-mentioned electromagnetic wave shielding material, the magnetic layer sandwiched between two metal layers contains an acrylic resin. In the present invention and this specification, "acrylic resin" refers to a polymer of a (meth)acrylate compound. The polymer includes homopolymers and copolymers. In the present invention and this specification, "(meth)acrylate compound" refers to a compound containing one or more (meth)acryloyl groups per molecule, and the term "(meth)acryloyl group" is used to refer to either or both of an acryloyl group and a methacryloyl group. Furthermore, a (meth)acryloyl group may be included in a (meth)acrylate compound in the form of a (meth)acryloyloxy group. The term "(meth)acryloyloxy group" is intended to refer to either or both of an acryloyloxy group and a methacryloyloxy group.

[0032] Examples of (meth)acrylate compounds include butyl acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, and t-butyl acrylate; cyclohexyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, and benzyl acrylate; and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, hexyl methacrylate, and benzyl methacrylate; and the like. These may be used alone or in combination of two or more. The present inventors speculate that polymers of acrylic acid esters (including homopolymers and copolymers) may contribute to a higher degree of crosslinking in the magnetic layer compared to polymers of methacrylic acid esters (including homopolymers and copolymers). The inventors also believe that polymers of acrylic acid esters (including homopolymers and copolymers) tend to lower the glass transition temperature Tg of the magnetic layer compared to polymers of methacrylic acid esters (including homopolymers and copolymers).

[0033] In one embodiment, the acrylic resin may have an alkyl(meth)acrylate structure. In the present invention and this specification, the term "alkyl(meth)acrylate structure" refers to a partial structure represented by the following formula A:

[0034]

[0035] In formula A, R １０ represents a hydrogen atom or a methyl group. １０ When R is a hydrogen atom, the partial structure represented by formula A is called an alkyl acrylate structure, and R １０is a methyl group, the partial structure represented by formula A is called an alkyl methacrylate structure, and the term "alkyl (meth)acrylate structure" is used to encompass such structures. In the present invention and this specification, an "*" in a partial structure indicates the bonding position where that partial structure is bonded to another partial structure. The acrylic resin can be a homopolymer or copolymer containing one or more types of alkyl (meth)acrylate structures as repeating units.

[0036] In formula A, R １１ In the present invention and this specification, the number of carbon atoms in the alkyl (meth)acrylate structure is determined by the number of carbon atoms in the alkyl group R in formula A. １１ R refers to the number of carbon atoms in the alkyl group represented by the formula: １１ The alkyl group represented by R may be an unsubstituted alkyl group or an alkyl group having a substituent, and is preferably an unsubstituted alkyl group. １１ The number of carbon atoms in the alkyl group represented by R １１ In the case where the alkyl group represented by the formula (I) has a substituent, the number of carbon atoms refers to the number of carbon atoms in the portion other than the substituent. Examples of the substituent include alkyl groups (e.g., alkyl groups having 1 to 6 carbon atoms), hydroxy groups, alkoxy groups (e.g., alkoxy groups having 1 to 6 carbon atoms), and halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, etc.). The glass transition temperature Tg of the magnetic layer can be affected by the structure of the acrylic resin contained in the magnetic layer. From the viewpoint of controlling the glass transition temperature Tg of the magnetic layer within the range described above, it is preferable to use R １１ The number of carbon atoms in the alkyl group represented by R is preferably 2 or more. １１ The number of carbon atoms in the alkyl group represented by the formula (I) is preferably 8 or less, more preferably 7 or less, and further preferably 6 or less, 5 or less, and 4 or less in that order.

[0037] An example of the acrylic resin is a copolymer of at least one compound selected from the group consisting of a hydroxy group-containing compound, an unsaturated carboxylic acid, and a compound represented by the following formula 3 with a (meth)acrylate compound.

[0038] Formula 3 CH ２ = C(X)R１

[0039] In formula 3, R １ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, a —CN group, or a —CO—R ２ group, —O—CO—R ３ group, -OR ４ group or -(CH ２ ) ｎ -O-R ５ represents a group. ２ , R ３ , R ４ and R ５ each independently represents a hydrogen atom or an organic group having 1 to 20 carbon atoms, and the organic group may contain a halogen atom, a glycidyl group, etc. n represents an integer of 1 or more and 6 or less.

[0040] Examples of the hydroxy group-containing compound include 2-(hydroxyalkyl)acrylic acid esters such as α-hydroxymethylstyrene, α-hydroxyethylstyrene, and methyl 2-(hydroxyethyl)acrylate; and 2-(hydroxyalkyl)acrylic acids such as 2-(hydroxyethyl)acrylic acid; and these may be used alone or in combination of two or more.

[0041] Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, crotonic acid, α-substituted acrylic acid, and α-substituted methacrylic acid. These may be used alone or in combination of two or more.

[0042] Examples of the compound represented by formula 3 include styrene, vinyl toluene, α-methyl styrene, acrylonitrile, methyl vinyl ketone, ethylene, propylene, vinyl acetate, 2-chloroethyl vinyl ether, chlorovinyl acetate, allyl glycidyl ether, glycidyl methacrylate, and glycidyl acrylate. These may be used alone or in combination of two or more.

[0043] The acrylic resin contained in the magnetic layer may be a commercially available acrylic resin or an acrylic resin synthesized by a known method. For details on the synthesis method of the acrylic resin, see, for example, paragraphs 0016 to 0038 of JP-A No. 2002-140567 and the examples therein.

[0044] From the viewpoint of further improving heat resistance and further from the viewpoint of the self-supporting properties of the magnetic layer, the content of the acrylic resin in the magnetic layer is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, where the total mass of the magnetic layer is 100 parts by mass. Also, from the viewpoint of further improving the shielding ability of the electromagnetic wave shielding material, the total content of the acrylic resin in the magnetic layer is preferably less than 30 parts by mass, more preferably 28 parts by mass or less, even more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, where the total mass of the magnetic layer is 100 parts by mass.

[0045] In addition to the above components, the magnetic layer may also contain any amount of one or more known additives, such as a crosslinking agent, a dispersant, a stabilizer (for example, an antioxidant, a light stabilizer such as HALS (Hindered Amine Light Stabilizer)), an antifoaming agent, an adhesion improver for metals, or an adhesion improver for resins.

[0046] A crosslinking agent is a compound capable of forming a crosslinked structure, and can be included in the magnetic layer in a state in which a crosslinked structure is formed. The degree of crosslinking of the magnetic layer can also be controlled by the amount of crosslinking agent used. From the viewpoint of controlling the degree of crosslinking of the magnetic layer within the range described above, the content of the crosslinking agent in the magnetic layer is preferably 0.05 parts by mass or more and 2.00 parts by mass or less, and more preferably 0.05 parts by mass or more and 0.50 parts by mass or less, based on 100 parts by mass of the total mass of the magnetic layer.

[0047] Regarding the crosslinking agent, preferred crosslinking agents for controlling the degree of crosslinking of the magnetic layer within the range described above include one or more crosslinking agents selected from the group consisting of silane coupling agents and polyfunctional amine compounds.

[0048] Silane coupling agents are organosilicon compounds having an organic group and a hydrolyzable group, such as an alkoxy group, an acyloxy group, or a halogeno group.

[0049] The silane coupling agent may have a hydrophobic group. Examples of the silane coupling agent having a hydrophobic group as a functional group include alkoxysilanes such as methyltrimethoxysilane (MTMS), dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, and decyltrimethoxysilane; chlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, and phenyltrichlorosilane; and hexamethyldisilazane (HMDS).

[0050] The silane coupling agent may also have a vinyl group. Examples of the silane coupling agent having a vinyl group include alkoxysilanes such as methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane and vinylmethyldichlorosilane; and divinyltetramethyldisilazane.

[0051] The silane coupling agent may also have an amino group. Examples of the silane coupling agent having an amino group include aminopropyltriethoxysilane, aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-8-aminooctyltrimethoxysilane, aminoalkoxysilanes having amines at both ends (e.g., FM-3311, FM-3321, and FM-3325 manufactured by JNC Corporation), and polyfunctional amine aminoalkoxysilanes (e.g., X-12-972F manufactured by Shin-Etsu Chemical Co., Ltd.).

[0052] Examples of crosslinked structures that can be formed by a silane coupling agent include a crosslinked structure formed by hydrolysis and condensation of the alkoxysilane portion of the silane coupling agent, and a crosslinked structure formed by the reaction of a functional group (e.g., an amino group) of the silane coupling agent with a functional group (e.g., a halogen atom) of the acrylic resin and condensation of the alkoxysilane portion.

[0053] The polyfunctional amine compound is a compound having an amino group (-NH ２ ) per molecule. Diamine compounds having two or more amino groups per molecule are preferred as polyfunctional amine compounds. Specific examples of diamine compounds include those listed in Tokyo Chemical Industry Co., Ltd.'s diamine monomer catalog (URL: https: / / www.tcichemicals.com / assets / brochure-pdfs / Brochure_FF046_J.pdf). Diamine compounds that are more preferred for controlling the degree of crosslinking of the magnetic layer within the range described above include 1,8-octanediamine, 1,10-decanediamine, 1,12-dodecanediamine, 1,8-diamino-3,6-dioxaoctane, 1,4-bis(3-aminopropoxy)butane, bis[2-(3-aminopropoxy)]ethyl ether, triethylenetetramine, and N,N'-bis(2-aminoethyl)-1,3-propanediamine.

[0054] An example of a crosslinked structure that can be formed by a polyfunctional amine compound is a crosslinked structure formed by a reaction between an amino group of the polyfunctional amine compound and a functional group (e.g., a glycidyl group) of an acrylic resin.

[0055] The magnetic layer may contain one or more compounds selected from the group consisting of compounds represented by Formula 1 and compounds represented by Formula 2. The inventors believe that such compounds can function as adhesion improvers, such as adhesion improvers for metals and resins, and can contribute to improving the adhesion between the magnetic layer and a layer adjacent to it without any intervening layer, i.e., the adhesion between the magnetic layer and a layer in direct contact with the magnetic layer. An example of a layer in direct contact with the magnetic layer is a metal layer. External forces may be applied to electromagnetic shielding materials during molding, and even after molding and incorporation into electronic components or electronic devices, external forces may be applied, for example, by dropping or impact. Durability that can withstand such external forces is a desirable performance for an electromagnetic shielding material. High adhesion between two directly adjacent layers in an electromagnetic shielding material makes it less likely for peeling to occur between the magnetic layer and the metal layer when external force is applied to the electromagnetic shielding material. Suppressing the occurrence of such peeling is preferable because it leads to improved durability of the electromagnetic shielding material.

[0056]

[0057] In formula 1, R １ , R ２ and R ３ are each independently a hydrogen atom, an allyl group (CH ２ =CH-CH ２ -), organic groups containing a hydroxy group (-OH), organic groups containing a carboxy group (-COOH), alkoxysilyl groups (-Si(OR) ３ : R represents an alkyl group.) or a glycidyl group (epoxy group -CH ２ -) represents. １ , R ２ and R ３may all be the same, may all be different, or two may be the same.

[0058] The organic group containing a hydroxy group can be an organic group in which a hydroxy group is bonded to a divalent linking group. The divalent linking group is not particularly limited. The divalent linking group can be, for example, an unsubstituted hydrocarbon group or a substituted hydrocarbon group. For the substituent possessed by the substituted hydrocarbon group, reference can be made to the description below regarding the substituent that may be possessed by the alkyl group R contained in the alkoxysilyl group. The organic group containing a hydroxy group can be, for example, -(CH ２ ) ｎ Examples of organic groups include, but are not limited to, organic groups represented by the formula -OH. The above n represents an integer of 1 or more, for example, an integer in the range of 1 to 6.

[0059] The organic group containing a carboxy group can be an organic group in which a carboxy group is bonded to a divalent linking group. The divalent linking group is not particularly limited. The divalent linking group can be, for example, an unsubstituted hydrocarbon group or a substituted hydrocarbon group. For the substituent possessed by the substituted hydrocarbon group, reference can be made to the description below regarding the substituent that may be possessed by the alkyl group R contained in the alkoxysilyl group. The organic group containing a carboxy group can be, for example, -(CH ２ ) ｎ Examples of organic groups include, but are not limited to, organic groups represented by the formula -COOH. The above n represents an integer of 1 or more, for example, an integer ranging from 1 to 6.

[0060] Alkoxysilyl group (—Si(OR) ３In the formula (1), the three R's may all be the same, all be different, or two may be the same. The alkyl group represented by R may be an unsubstituted alkyl group or an alkyl group having a substituent, and is preferably an unsubstituted alkyl group. When the alkyl group represented by R is an alkyl group having a substituent, the number of carbon atoms in the alkyl group represented by R refers to the number of carbon atoms in the portion other than the substituent. Examples of substituents that the alkyl group represented by R may have include alkyl groups (e.g., alkyl groups having 1 to 6 carbon atoms), hydroxy groups, alkoxy groups (e.g., alkoxy groups having 1 to 6 carbon atoms), and halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, etc.). The number of carbon atoms in the alkyl group represented by R may be one or more or two or more. The number of carbon atoms in the alkyl group represented by R may be 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, or 3 or less. The compound represented by Formula 1 may exist in the magnetic layer in a form in which the alkoxysilyl group is hydrolyzed.

[0061] Alkoxysilyl group (—Si(OR) ３ The organic group containing an alkoxysilyl group (-Si(OR)) can be an organic group in which an alkoxysilyl group is bonded to a divalent linking group. The divalent linking group is not particularly limited. The divalent linking group can be, for example, an unsubstituted hydrocarbon group or a substituted hydrocarbon group. For the substituents that the substituted hydrocarbon group has, reference can be made to the above description of the substituents that the alkyl group represented by R may have. The alkoxysilyl group (-Si(OR)) ３ An example of an organic group containing -(R) is -(CH ２ ) ｎ -Si(OR) ３ However, the organic group is not limited to this example. The above n represents an integer of 1 or more, for example, an integer in the range of 1 to 6.

[0062] The compound represented by Formula 1 may have keto-enol tautomerism. For compounds having keto-enol tautomerism, Formula 1 shows the form of the keto isomer. In the present invention and this specification, for compounds having keto-enol tautomerism, the compound represented by Formula 1 also includes the case where it exists in the form of the enol isomer. As an example, cyanuric acid (in Formula 1, R １ , R ２ and R ３ represents a hydrogen atom. The enol isomer of the compound represented by formula 1-1 can be represented by the following formula 1-1. The compound represented by formula 1 may also exist as a metal complex such as a zinc complex. In the present invention and this specification, the compound represented by formula 1 also includes metal complexes of the compound represented by formula 1.

[0063]

[0064] The compound represented by Formula 1 may also exist as a mixture of the compound represented by Formula 1 and melamine. One example of such a mixture is melamine cyanurate. Melamine cyanurate is a mixture of melamine and cyanuric acid (R １ , R ２ and R ３ represents a hydrogen atom. Melamine is an example of a compound represented by formula 2, the details of which will be described later. In melamine, R in formula 2 ４ , R ５ and R ６ is an amino group (-NH ２ ) represents

[0065] Specific examples of the compound represented by Formula 1 include cyanuric acid, cyanuric acid-zinc complex, melamine cyanurate, diallyl monoglycidyl isocyanurate, monoallyl diglycidyl isocyanurate, tris[3-(trimethoxysilyl)propyl] isocyanurate, tris(2-hydroxyethyl) isocyanurate, tris(2-carboxyethyl) isocyanurate, bis(2-carboxyethyl) isocyanurate, etc. Specific examples of commercially available products include Starfine F-10 manufactured by Nissan Chemical Industries, Ltd., Melamine Cyanurate MC-4000, MC-4500, MC-6000 manufactured by Nissan Chemical Industries, Ltd., and KBM-9659 manufactured by Shin-Etsu Chemical Co., Ltd. However, the compound represented by Formula 1 is not limited to the above specific examples.

[0066]

[0067] In formula 2, R ４ , R ５ and R ６ are each independently an amino group (-NH ２ ) or an alkoxysilyl group (—Si(OR) ３ : R represents an alkyl group.) represents an organic group containing.

[0068] R ４ , R ５ and R ６ may all be the same, may all be different, or two may be the same.

[0069] Alkoxysilyl group (—Si(OR) ３ ) can be referred to the above description of Formula 1. The compound represented by Formula 2 can exist in the magnetic layer in a form in which the alkoxysilyl group is hydrolyzed.

[0070] Alkoxysilyl group (—Si(OR) ３The organic group containing an alkoxysilyl group (-Si(OR)) can be an organic group in which an alkoxysilyl group is bonded to a divalent linking group. The divalent linking group is not particularly limited. The divalent linking group can be, for example, an unsubstituted hydrocarbon group, a substituted hydrocarbon group, an -NH- group, or a combination of two or more of these groups. For the substituents that the substituted hydrocarbon group has, reference can be made to the above description of the substituents that the alkyl group represented by R may have. The alkoxysilyl group (-Si(OR)) ３ An example of an organic group containing an alkyl group is —NH—(CH ２ ) ｎ -Si(OR) ３ However, the organic group is not limited to this example. The above n represents an integer of 1 or more, for example, an integer in the range of 1 to 6.

[0071] A specific example of a commercially available product of the compound represented by formula 2 is VD-5 manufactured by Shikoku Chemicals Co., Ltd. As described above, an example of the compound represented by formula 2 is melamine (in formula 2, R ４ , R ５ and R ６ is an amino group (-NH ２ ) can be mentioned, and melamine may exist as a mixture with the compound represented by formula 1. A specific example of such a mixture is melamine cyanurate. Specific examples of commercially available melamine cyanurate products are as described above. However, the compound represented by formula 2 is not limited to the above specific examples.

[0072] When the magnetic layer contains one or more compounds selected from the group consisting of compounds represented by Formula 1 and compounds represented by Formula 2, the magnetic layer may contain only one or more compounds represented by Formula 1 as the compounds selected from the group consisting of compounds represented by Formula 1 and compounds represented by Formula 2, or may contain only one or more compounds represented by Formula 1 and one or more compounds represented by Formula 2. When the magnetic layer contains one or more compounds selected from the group consisting of compounds represented by Formula 1 and compounds represented by Formula 2, the content of these compounds in the magnetic layer (the total content if multiple compounds are included) can be, for example, 0.01 to 4.00 parts by mass, with the total mass of the magnetic layer being 100 parts by mass. Note that when the compound represented by Formula 1 is a metal complex, the content refers to the content as the metal complex.

[0073] The present inventors speculate that, from the viewpoint of improving the formability of the electromagnetic wave shielding material, it is preferable for the magnetic layer to contain one or more compounds selected from the group consisting of compounds represented by Formula 1 and compounds represented by Formula 2. The present inventors believe that the compound represented by Formula 1 is more preferable from the viewpoint of improving formability.

[0074] 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 further 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, and it is preferably less than 90 μm, and more preferably 80 μm or less. The thickness of each of the two or more magnetic layers can be the same or different.

[0075] The thickness of each layer included in the electromagnetic wave shielding material is determined by photographing a cross section exposed by a known method with a scanning electron microscope (SEM) and calculating the arithmetic mean of the thicknesses at five randomly selected points in the resulting SEM image.

[0076] <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 also applies when the electromagnetic shielding material includes two or more magnetic layers, and when the electromagnetic shielding material includes two or more other layers, such as a resin layer, as described below.

[0077] 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.

[0078] 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 electromagnetic wave 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 metal Cu or Al or an alloy containing Cu or Al as a main component is preferred, and from the viewpoint of high electrical conductivity, pure metal Cu or an alloy containing Cu as a main component is more preferred.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] With regard 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. In the electromagnetic wave shielding material, the thicknesses of the multiple metal layers can be the same or different.

[0083] In one embodiment, one or both outermost layers of the electromagnetic shielding material can be a metal layer. This can contribute to the electromagnetic shielding material being able to exhibit high shielding ability against magnetic fields in the low-frequency range of around 100 kHz to 1 MHz. Furthermore, having at least one outermost layer of the electromagnetic shielding material be a metal layer can also contribute to suppressing edge peeling in a molded product obtained by molding. In one embodiment, one or both outermost layers of the electromagnetic shielding material can be a metal layer that sandwiches a magnetic layer with another metal layer.

[0084] In one embodiment, in the multilayer structure of the electromagnetic wave shielding material in which a magnetic layer is sandwiched between two metal layers, one or both of the two metal layers can be disposed as layers in direct contact with the magnetic layer. That is, one or both of the two metal layers can be adjacent to the magnetic layer without any other layer interposed therebetween. Also, in one embodiment, the multilayer structure of the electromagnetic wave shielding material in which a magnetic layer is sandwiched between two metal layers can have one or more resin-containing layers between one or both of the two metal layers and the magnetic layer. The resin-containing layer is a layer containing one or more types of resin. Specific embodiments of the resin-containing layer are described below.

[0085] <Layer Containing Resin> (Adhesive Layer) One example of a resin-containing layer is an adhesive layer. In the present invention and this specification, the term "adhesive layer" refers to a layer having 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 little 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.

[0086] 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.

[0087] 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.

[0088] (Adhesive Layer) One form of a 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 state change such as drying or curing, 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 that has no tackiness on the surface at room temperature. 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 dissolve in a solvent to become liquid or gel-like. Examples of solvents contained in the adhesive 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.

[0089] 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.

[0090] (Resin Layer) One form of layer containing a resin 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 elastomer (PP), styrene 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.

[0091] The resin layer can be bonded to a metal layer or a magnetic layer via an adhesive layer or a pressure-sensitive adhesive layer. Since the resin layer contains a thermoplastic resin, 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 an adhesive layer or a pressure-sensitive adhesive layer.

[0092] The thickness of the resin layer, expressed as the thickness of each resin layer, is preferably 10 μm or more, and more preferably 12 μm or more. The thickness of the resin layer, expressed as the thickness of each resin layer, is preferably 250 μm or less, more preferably 230 μm or less, even more preferably 210 μm or less, and even more preferably 190 μm or less. In one embodiment, the electromagnetic wave shielding material has a multilayer structure in which a magnetic layer is sandwiched between two metal layers, and can include one or more resin layers having a thickness within the above range between one or both of the two metal layers and the magnetic layer. For example, the multilayer structure can include one resin layer having a thickness within the above range between one of the two metal layers and the magnetic layer, and / or between the other metal layer and the magnetic layer.

[0093] The electromagnetic wave shielding material can contain, in one or more of the resin-containing layers, one or more compounds selected from the group consisting of the compound represented by Formula 1 and the compound represented by Formula 2. The layer containing such a compound can be one or more layers selected from the group consisting of an adhesive layer, a pressure-sensitive adhesive layer, and a resin layer. When the resin-containing layer contains one or more compounds selected from the group consisting of the compound represented by Formula 1 and the compound represented by Formula 2, reference can be made to the above description regarding the case where such a compound is contained in the magnetic layer.

[0094] <Specific Example of Layer Configuration> The total number of magnetic layers included in the electromagnetic shielding material is one or more, and can be two or more, or can be, for example, four or less. On the other hand, the total number of metal layers included in the electromagnetic shielding material is two or more, and can be, for example, two to five. When the electromagnetic shielding material includes only one magnetic layer, this one magnetic layer is a magnetic layer sandwiched between two metal layers. When the electromagnetic 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 a portion of the magnetic layers included in the electromagnetic shielding material are magnetic layers sandwiched between two metal layers.

[0095] In one embodiment, in a multilayer structure in which a magnetic layer is sandwiched between two metal layers, the magnetic layer can be in direct contact with both metal layers. In this case, specific examples of the layer configuration of the electromagnetic shielding material include the following: Example A1: "Metal layer / Magnetic layer / Metal layer" Example A2: "Metal layer / Magnetic layer / Metal layer / Magnetic layer / Metal layer" Example A3: "Metal layer / Magnetic layer / Metal layer / Magnetic layer / Metal layer / Magnetic layer / Metal layer" In an electromagnetic shielding material including two or more multilayer structures each including a magnetic layer between two metal layers, as in Examples A2 and A3, the metal layers sandwiching the magnetic layer in one multilayer structure can also be the metal layers sandwiching the magnetic layer in another multilayer structure. In the electromagnetic shielding material, the total number of multilayer structures each including the magnetic layer between two metal layers can be, for example, one to four. The total number of multilayer structures is one in Example A1, two in Example A2, and three in Example A3. It is preferable that the total number of the multilayer structure is two or more (e.g., two, three, or four) from the viewpoint of further improving the shielding ability of the electromagnetic wave shielding material. In the above, the symbol " / " means that the layer written to the left of this symbol and the layer written to the right of this symbol are in direct contact with each other without any other layer in between. This point also applies to the following description unless otherwise specified.

[0096] In another embodiment, the multilayer structure of the electromagnetic wave shielding material, in which a magnetic layer is sandwiched between two metal layers, can include one or more resin-containing layers between one or both of the two metal layers and the magnetic layer. In the multilayer structure, one of the two metal layers can be adjacent to the magnetic layer without any other layer in between, and one or more resin-containing layers can be included between the other metal layer and the magnetic layer. Alternatively, the multilayer structure can have one or more resin-containing layers between each of the two metal layers and the magnetic layer. As the resin-containing layer located between the metal layer and the magnetic layer, at least a resin layer is preferred. In one embodiment, the electromagnetic wave shielding material can include one or more polyester resin-containing layers between one or both of the two metal layers and the magnetic layer, and the polyester resin-containing layer is preferably a resin layer.

[0097] The multilayer structure may include an adhesive layer and / or a bonding layer between the resin layer and the metal layer. In one embodiment, the adhesive layer and / or the bonding layer may be included between the resin layer and the magnetic layer. In another embodiment, the resin layer and the magnetic layer may be in direct contact with each other in the multilayer structure. That is, the resin layer and the magnetic layer may be adjacent to each other without any other layer interposed therebetween.

[0098] The electromagnetic wave shielding material may include, for example, a total of 1 to 12 resin-containing layers. The total number of resin layers included in the electromagnetic wave shielding material (preferably resin layers having the thickness described above) may be, for example, 1 to 4. The total number of layers selected from the group consisting of pressure-sensitive adhesive layers and adhesive layers included in the electromagnetic wave shielding material may be, for example, 1 to 4 or 1 to 8.

[0099] The following are examples of the arrangement of the "magnetic layer," "metal layer," "resin layer," and "adhesive or bonding layer" in the electromagnetic wave shielding material. In the following examples, the "adhesive layer" may include a support, or the "adhesive layer" may be an adhesive tape having an adhesive layer on one or both sides of the support. For example, as in Example B3, the metal layer sandwiching one magnetic layer may also be the metal layer sandwiching another magnetic layer. For example, in Example B3, 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. Furthermore, in Example B3, the outermost layer on one side of the electromagnetic wave shielding material is metal layer 1, which sandwiches magnetic layer 1 together with metal layer 2, and the outermost layer on the other side of the electromagnetic wave shielding material is metal layer 3, which sandwiches magnetic layer 2 together with metal layer 2. Example B1: "Metal layer 1 / adhesive layer 1 or adhesive layer 1 / resin layer 1 / magnetic layer 1 / resin layer 2 / adhesive layer 2 or adhesive layer 2 / metal layer 2" Example B2: "Metal layer 1 / adhesive layer 1 or adhesive layer 1 / resin layer 1 / magnetic layer 1 / metal layer 2 / adhesive layer 2 or adhesive layer 2 / resin layer 2" Example B3: "Metal layer 1 / adhesive layer 1 or adhesive layer 1 / resin layer 1 / magnetic layer 1 / resin layer 2 / adhesive layer 2 or adhesive layer 2 / metal layer 2 / adhesive layer 3 or adhesive layer 3 / resin layer 3 / magnetic layer 2 / resin layer 4 / adhesive layer 4 or adhesive layer 4 / metal layer 3" Example B4: "Metal layer 1 / adhesive layer 1 or adhesive layer 1 / resin layer 1 / magnetic layer 1 / metal layer 2 / adhesive layer 2 or adhesive layer 2 / resin layer 2 / magnetic layer 2 / resin layer 3 / adhesive layer 3 or adhesive layer 3 / metal layer 3" Example B5: "Metal layer 1 / adhesive layer 1 or adhesive layer 1 / resin layer 1 / magnetic layer 1 / metal layer 2 / adhesive layer 2 or adhesive layer 2 / resin layer 2 / magnetic layer 2 / metal layer 3 / adhesive layer 3 or adhesive layer 3 / resin layer 3" Example B6: "Metal layer 1 / adhesive layer 1 or adhesive layer 1 / resin layer 1 / magnetic layer 1 / metal layer 2 / magnetic layer 2 / resin layer 2 / adhesive layer 2 or adhesive layer 2 / metal layer 3" Example B7: "Metal layer 1 / adhesive layer 1 or adhesive layer 1 / resin layer 1 / magnetic layer 1 / metal layer 2 / magnetic layer 2 / metal layer 3 / adhesive layer 2 or adhesive layer 2 / resin layer 2" Example B8: "Metal layer 1 / adhesive layer 1 or adhesive layer 1 / resin layer 1 / magnetic layer 1 / resin layer 2 / adhesive layer 2 or adhesive layer 2 / metal layer 2 / magnetic layer 2 / resin layer 3 / adhesive layer 3 or adhesive layer 3 / metal layer 3"

[0100] In another embodiment, the multilayer structure of the electromagnetic shielding material in which a magnetic layer is sandwiched between two metal layers can be a multilayer structure in which two or more magnetic layers are sandwiched between the two metal layers. Such a multilayer structure can also include one or more layers containing a resin between two adjacent magnetic layers. For example, the multilayer structure of the electromagnetic shielding material in which a magnetic layer is sandwiched between two metal layers can have two magnetic layers between the two metal layers and one layer containing a resin between the two magnetic layers. A specific example of the layer configuration of an electromagnetic shielding material having such a multilayer structure can be Example B9 below. Example B9: "Metal Layer 1 / Magnetic Layer 1 / Resin Layer 1 / Magnetic Layer 2 / Metal Layer 2"

[0101] <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 further 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] The magnetic layer-forming composition can also be applied to the surface of the previously described layers, such as a metal layer or a resin layer. For example, by applying the magnetic layer-forming composition to the surface of a metal layer or a resin layer and, if necessary, applying a pressure treatment to the magnetic layer described below, it is possible to produce a multilayer partial structure ("magnetic layer / metal layer" or "magnetic layer / resin layer") in which a magnetic layer is sandwiched between two metal layers of an electromagnetic wave shielding material. As an example, an electromagnetic wave shielding material having the layer structure of Example A1 "metal layer / magnetic layer / metal layer" described above can be produced by applying pressure and heat to two "magnetic layer / metal layer" partial structures with the magnetic layer sides facing each other and crimping them together.

[0106] 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.

[0107] The degree of orientation of the flat particles described above can be controlled by the type of solvent, amount of solvent, liquid viscosity, coating thickness, etc., of the magnetic layer-forming composition. For example, if the boiling point of the solvent is low, convection occurs upon drying, which tends to increase the degree of orientation. If the amount of solvent is small, the degree of orientation tends to increase due to physical interference between adjacent flat particles. On the other hand, if the liquid viscosity is low, the flat particles are more likely to rotate, which tends to decrease the degree of orientation. If the coating thickness is made thinner, the degree of orientation tends to decrease. In addition, performing the pressure treatment described below can contribute to reducing the degree of orientation. By adjusting the various manufacturing conditions described above, the degree of orientation of the flat particles can be controlled within the range described above.

[0108] (Pressure treatment of magnetic layer) The magnetic layer can also be subjected to pressure treatment after film formation. By pressure treating a magnetic layer containing magnetic particles, the magnetic particle density in the magnetic layer can be increased, resulting in higher magnetic permeability. Furthermore, for a magnetic layer containing flat-shaped particles, the degree of orientation can be reduced by pressure treatment, resulting in higher magnetic permeability.

[0109] The pressure treatment can be carried out by applying pressure in the thickness direction of the magnetic layer using a plate press, a roll press, or the like. With a plate press, the object to be pressed is placed between two flat press plates arranged above and below, and pressure can be applied to the object by bringing the two press plates together using mechanical or hydraulic pressure. With a roll press, the object to be pressed is passed 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.

[0110] The pressure during the pressurization can be set arbitrarily. For example, in the case of a plate-type press, the pressure is set to, for example, 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 can be set as desired. When a plate press is used, the time is, for example, 5 seconds to 30 minutes. When a roll press is used, the pressure application 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 pressure treatment, heat can be applied to both the upper and lower press plates of a plate press or to one of the press plates or 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.

[0111] (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 directly contacts an adjacent layer, the magnetic layer softens in the bonding step, promoting contact with the surface of the adjacent layer, 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 / 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.

[0112] 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 referred to as cold molding. In one embodiment, the electromagnetic shielding material exhibits excellent formability in cold forming and is suitable for cold forming such as drawing and stretch forming. Drawing is a molding method in which a sheet-like object is pressed using a pair of dies, one female and one male, 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, without a 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). The electromagnetic shielding material can be an electromagnetic shielding material that is difficult to break when formed by such a three-dimensional forming method. Publicly known techniques can be applied to the three-dimensional forming method.

[0113] Another aspect of the present invention relates to an electromagnetic wave shielding material having a magnetic layer containing magnetic particles and a resin between two metal layers, the magnetic layer containing one or more compounds selected from the group consisting of the compound represented by Formula 1 above and the compound represented by Formula 2 above.

[0114] Another aspect of the present invention relates to an electromagnetic wave shielding material having one or more layers containing a resin and one or more compounds selected from the group consisting of the compound represented by Formula 1 and the compound represented by Formula 2. The layer can be one or more layers selected from the group consisting of a magnetic layer, an adhesive layer, an adhesive layer, and a resin layer.

[0115] A compound selected from the group consisting of compounds represented by Formula 1 and compounds represented by Formula 2 can contribute to improving the adhesion between two layers in an electromagnetic wave shielding material. Furthermore, a compound selected from the group consisting of compounds represented by Formula 1 and compounds represented by Formula 2 (preferably the compound represented by Formula 1) can contribute to improving the formability of the electromagnetic wave shielding material.

[0116] For details of any of the above-mentioned electromagnetic wave shielding materials, please refer to the above descriptions.

[0117] [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.

[0118] [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.

[0119] One example of a use of the electromagnetic shielding material is to cover a semiconductor package on a printed circuit board with the electromagnetic shielding material. For example, "Electromagnetic Shielding Technology for Semiconductor Packages" (Toshiba Review Vol. 67 No. 2 (2012) p. 8) discloses a method for achieving high shielding effectiveness by electrically connecting a side via at the end of the package substrate to the inner surface of the electromagnetic shielding material when covering a semiconductor package with the electromagnetic shielding material, thereby achieving ground wiring. To achieve such wiring, it is desirable for the outermost layer of the electromagnetic shielding material on the electronic component side to be a metal layer. When one or both outermost layers of the electromagnetic shielding material are metal layers, the electromagnetic shielding material can be suitably used for such wiring.

[0120] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the embodiments shown in the examples. "Parts" in the following descriptions are "parts by mass."

[0121] [Magnetic Layer Resin] Regarding the magnetic layer resins shown in Table 1, "Acrylic Resin 1" is an acrylic rubber product name Nipol model number AR71 manufactured by Zeon Corporation. Acrylic Resin 1 is an acrylic resin (solid concentration 100% by mass) synthesized using ethyl acrylate as the (meth)acrylate compound and vinyl chloroacetate as the compound represented by Formula 3.

[0122] "Acrylic resin 2" is an acrylic rubber product name Nipol model number AR51 manufactured by Zeon Corporation. Acrylic resin 2 is an acrylic resin (solid concentration 100% by mass) synthesized using ethyl acrylate as the (meth)acrylate compound and allyl glycidyl ether as the compound represented by formula 3.

[0123] "Acrylic resin 3," "acrylic resin 4," "acrylic resin 5," and "acrylic resin 6" are acrylic resins synthesized by the following method. Emulsion polymerization and slurry formation were carried out according to the synthesis example described in paragraph 0097 of JP 2022-140567 A, except that "15 parts of ethyl acrylate, 55 parts of n-butyl acrylate, 28 parts of methoxyethyl acrylate, and 2 parts of mono-n-butyl fumarate" described in the same paragraph were changed as follows. The obtained slurry was dried under reduced pressure in a vacuum dryer with an internal atmosphere temperature of 80°C to obtain an acrylic resin (solids concentration 100% by mass).

[0124] Acrylic resin 3: 97 parts of butyl acrylate, 3 parts of vinyl chloroacetate. Acrylic resin 4: 50 parts of ethyl acrylate, 47 parts of hexyl methacrylate, 3 parts of vinyl chloroacetate. Acrylic resin 5: 97 parts of octyl acrylate, 3 parts of vinyl chloroacetate. Acrylic resin 6: 97 parts of hexyl methacrylate, 3 parts of vinyl chloroacetate.

[0125] The numbers of carbon atoms in the alkyl groups of the alkyl(meth)acrylate structures of acrylic resins 1 to 6 are shown in Table 1. Acrylic resin 4 has an alkyl(meth)acrylate structure in which the alkyl group has 2 carbon atoms and an alkyl(meth)acrylate structure in which the alkyl group has 6 carbon atoms, and is therefore represented as "2 / 6" in Table 1.

[0126] The "urethane resin" is UR-8300 (solid content concentration: 30% by mass) manufactured by Toyobo Co., Ltd.

[0127] [Crosslinking Agent for Magnetic Layer] Regarding the crosslinking agents for the magnetic layer shown in Table 1, "KBM-903" is a silane coupling agent (trade name: KBM-903) manufactured by Shin-Etsu Silicones Co., Ltd. "C12DA" is a diamine monomer (1,12-dodecanediamine) manufactured by Tokyo Chemical Industry Co., Ltd. "Coronate L" is a polyisocyanate (trade name: Coronate L) manufactured by Tosoh Corporation.

[0128] Example 1 Preparation of Magnetic Layer-Forming Composition (Coating Liquid) To a plastic bottle were added 9.88 g of Fe—Si—Al flat-shaped magnetic particles (Sendust MFS-SUH manufactured by MKT Corporation), 2.42 g of acrylic resin (see Table 1), 0.0495 g of crosslinker (see Table 1), and 29 g of methyl ethyl ketone, and the mixture was mixed for 96 hours using a shaking stirrer to prepare a coating liquid (magnetic layer-forming composition). In the magnetic layer formed from the prepared coating liquid, the acrylic resin content and crosslinker content are the values ​​shown in Table 1, where the total mass of the magnetic layer is 100 parts by mass.

[0129] <Preparation of Magnetic Layer> (Deposition of Magnetic Layer) The coating liquid 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 the film was dried for 8 minutes in a drying device with an internal atmosphere temperature of 90°C, thereby forming a film-like magnetic layer on the release-treated PET film.

[0130] (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 30 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.

[0131] Measurement samples were cut out from the magnetic layer obtained above and used for various evaluations of the magnetic layer described below. However, measurement samples for various evaluations of the magnetic layer can also be taken from the electromagnetic wave shielding material by known methods.

[0132] <Preparation of Electromagnetic Wave Shielding Material> A magnetic layer cut out from the magnetic layer obtained above was used to prepare an electromagnetic wave shielding material. A 50 μm thick aluminum foil (JIS H4160:2006 compliant, alloy number 1N30, temper (1)O, Al content of 99.3 mass% or more) was used as the metal layer, and a laminate was prepared by overlapping three layers of "aluminum foil (metal layer) / magnetic layer / aluminum foil (metal layer)" without any other layer interposed between adjacent two layers. The upper and lower press plates of a plate press (Yamamoto Iron Works Co., Ltd., large hot press TA-200-1W) were heated to 140°C (internal temperature of the press plates), and the laminate was placed at the center of the press plates. The laminate was then compressed at a pressure of 4.66 N / mm. ２ The aluminum foil and the magnetic layer were thermocompression-bonded by applying a pressure of 0.05 MPa and maintaining this pressure for 15 minutes. The upper and lower press plates were cooled to 50°C (internal temperature of the press plates) while maintaining the pressure, and then the laminate was removed from the plate press. In this way, an electromagnetic wave shielding material having a layer structure of "aluminum foil (metal layer) / magnetic layer / aluminum foil (metal layer)" was obtained.

[0133] [Evaluation Method] <Measurement of magnetic permeability before and after thermal aging at 120°C> A measurement sample measuring 28 mm x 10 mm was cut out from the magnetic layer, and the magnetic permeability was measured using a magnetic permeability measuring device (Per01 manufactured by Keycom Corporation). The magnetic permeability was calculated as the real part of the complex relative magnetic permeability (μ') at a frequency of 3 MHz (measurement temperature: 25°C). The magnetic permeability calculated in this manner is referred to as the "magnetic permeability before thermal aging at 120°C." After measuring the magnetic permeability before thermal aging at 120°C, the measurement sample was placed in a high-temperature atmosphere at 120°C for 24 hours, and then the magnetic permeability was calculated using the above method (measurement temperature: 25°C). The magnetic permeability calculated in this manner is referred to as the "magnetic permeability after thermal aging at 120°C." Table 2 shows the evaluation results of the "magnetic permeability before thermal aging at 120°C" and the "magnetic permeability after thermal aging at 120°C" evaluated according to the following evaluation criteria. A: Magnetic permeability μ' is 100 or more B: Magnetic permeability μ' is 40 or more and less than 100 C: Magnetic permeability μ' is less than 40

[0134] <Measurement of Electrical Conductivity> A cylindrical main electrode with a diameter of 30 mm was connected to the negative pole of a digital insulation resistance meter (TR-811A manufactured by Takeda Riken Kogyo Co., Ltd.), and a ring electrode with an inner diameter of 40 mm and an outer diameter of 50 mm was connected to the positive pole. The main electrode and the ring electrode were placed in a position surrounding it on a sample piece of the magnetic layer cut to a size of 60 mm x 60 mm, and a voltage of 25 V was applied to both poles to measure the surface electrical resistivity of the magnetic layer alone. The electrical conductivity of the magnetic layer was calculated from the surface electrical resistivity and the following formula. The calculated electrical conductivity was 1.1 x 10 －２ The thickness was determined by the following method: Electrical conductivity [S / m] = 1 / (surface electrical resistivity [Ω] × thickness [m])

[0135] <Obtaining a Cross-Sectional Image of the Electromagnetic Shielding Material> Cross-section processing was performed to expose the cross section of the electromagnetic shielding material 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 electromagnetic 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 the magnetic layer and the thickness of each of the two metal layers were measured at five locations on the obtained image. The arithmetic mean of the thicknesses was taken as the thickness of the magnetic layer and the thickness of each metal layer. The thickness of the magnetic layer was 30 μm, and the thickness of each metal layer was 50 μm.

[0136] <Obtaining a cross-sectional image of the magnetic layer> In a cross-section of the electromagnetic wave shielding material that had been exposed by cross-section processing in the same manner as above, the magnetic layer portion was observed with a scanning electron microscope (SU8220 manufactured by Hitachi High-Technologies Corporation) under conditions of an acceleration voltage of 2 kV and a magnification of 1000 times, and a backscattered electron image was obtained.

[0137] <Measurement of aspect ratio of magnetic particles and degree of orientation of flat-shaped particles> Using the backscattered electron image obtained above, the aspect ratio of the magnetic particles was determined by the method described above, and the flat-shaped particles were identified from the aspect ratio value. Whether or not the magnetic layer contained flat-shaped particles was determined as described above, and it was determined that the magnetic layer contained flat-shaped particles. Furthermore, the degree of orientation of the magnetic particles identified as flat-shaped particles was determined by the method described above, and it was 13°. The average value (arithmetic mean) of the aspect ratios of all particles identified as flat-shaped particles was also determined as the aspect ratio of the flat-shaped particles contained in the magnetic layer. The determined aspect ratio was 0.071.

[0138] <Method for Measuring the Degree of Crosslinking of the Magnetic Layer> A measurement sample for TG / DTA measurement and a measurement sample for determining the mass of the solvent-insoluble component were cut from the magnetic layer. The proportion of the binder component (unit: mass%) was determined for the measurement sample for TG / DTA measurement using the method described above. Specifically, a Hitachi High-Tech Science TG / DTA 7300 was used as the TG / DTA measurement device. 3 mg of the measurement sample cut from the magnetic layer was placed in an alumina pan and measured under a nitrogen atmosphere at a temperature range of 23°C to 600°C and a heating rate of 10°C / min. The percentage mass loss at 600°C was taken as the proportion of the binder component (unit: mass%). The mass of the solvent-insoluble component was determined using the method described above using 70 mg of the measurement sample cut from the magnetic layer. The thus-determined values ​​for the mass of the solvent-insoluble component and the proportion of the binder component were used to calculate the degree of crosslinking using the formula described above. For example, in Example 1, the mass loss percentage at 600°C was 20%, so the proportion of the binder component in the magnetic layer was set to 20%. Therefore, the mass of the binder component in the measurement sample was calculated to be 70 mg x 0.2 = 14 mg. Since the mass of the solvent-insoluble component was 68.6 mg, the degree of crosslinking was calculated as follows: Degree of crosslinking = [1 - {(70 - 68.6) / 70 x 0.2}] x 100 = (1 - 0.1) x 100 = 90 (%)

[0139] <Method for measuring the glass transition temperature Tg of the magnetic layer> A measurement sample was cut out from the magnetic layer. Heat flow measurements were performed on the cut-out measurement sample using a DSC6200 differential scanning calorimeter manufactured by SII Technology under the following conditions. The same sample was subjected to two heating and cooling cycles, and the glass transition temperature Tg was determined using the results of the second heating. (Measurement conditions) Atmosphere in measurement chamber: Nitrogen (50 mL / min) Heating rate: 10°C / min Measurement start temperature: -100°C Measurement end temperature: 200°C Sample pan: Aluminum pan Mass of sample to be measured: 5 mg Calculation of glass transition temperature Tg: The midpoint between the start and end points of the decline in the DSC chart was taken as Tg.

[0140] <Evaluation of Shielding Ability Before and After Heat Aging at 120°C (KEC Method)> An electromagnetic shielding material cut to a size of 15 cm x 15 cm was placed between the antennas of a KEC method evaluation device including a signal generator, an amplifier, a pair of magnetic field antennas, and a spectrum analyzer. The ratio of the received signal strength without the electromagnetic shielding material to the received signal strength with the electromagnetic shielding material at a frequency of 100 kHz was calculated as the shielding ability. This was performed on the magnetic field antenna to determine the electromagnetic shielding ability (magnetic field shielding ability). KEC is an abbreviation for Kansai Electronics Industry Development Center. The shielding ability evaluated from the thus obtained value according to the following evaluation criteria is referred to as "shielding ability before heat aging at 120°C." After measuring the shielding ability before heat aging at 120°C, the electromagnetic shielding material was placed in a high-temperature atmosphere at 120°C for 24 hours, and then the shielding ability was determined using the above method. The shielding ability evaluated from the thus obtained value according to the following evaluation criteria is referred to as "shielding ability after heat aging at 120°C." The obtained evaluation results are shown in Table 2. (Evaluation criteria) A: 20 dB or more B: 15 dB or more but less than 20 dB C: Less than 15 dB

[0141] <Breaking Elongation of Electromagnetic Shielding Material> A measurement sheet measuring 100 mm in length and 10 mm in width was cut out from the electromagnetic shielding material of Example 1. This measurement sheet was attached to a tensile tester, and a tensile test was performed under the following measurement conditions. The tensile tester used was a Tensilon universal testing machine (RTF-1310) manufactured by A&D Corporation. To allow the measurement sheet to adapt to the measurement environment, the measurement sheet was left in the measurement environment for 15 minutes or more before being attached to the tensile tester and a tensile test was performed. The breaking elongation was calculated as "breaking elongation [unit: %] = 100 × L / distance between chucks," where L is the maximum elongation of the test sheet stretched in the tensile test (i.e., the elongation displacement in the longitudinal direction at the time when at least one layer of the measurement sheet breaks). The fact that at least one layer has broken can be determined by the stress reduction in the stress-strain curve, visual inspection, or the like. From the viewpoint of formability (e.g., formability in cold forming), it is preferable that the breaking elongation value thus obtained is 5% or more, more preferably 10% or more, even more preferably 15% or more, and even more preferably 25% or more. Furthermore, the breaking elongation can be, for example, 100% or less, 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, or 30% or less. From the viewpoint of improving formability, the larger the breaking elongation value, the more preferable. (Measurement conditions) Chuck distance: 50 mm Measurement environment: temperature 23°C, relative humidity 50% Load cell: 500 N (Newton) Tensile speed: 50 mm / min Tensile direction: length direction

[0142] <Moldability> The electromagnetic wave shielding material of Example 1 was draw-molded using a mold (manufactured by Amada Co., Ltd.) consisting of a male mold and a female mold at room temperature (25°C) without heating to produce a hemispherical three-dimensional molded product. The produced three-dimensional molded product was visually inspected for fractures, and the moldability was evaluated based on the inspection results using the following evaluation criteria. (Evaluation Criteria) A: A three-dimensional molded product with a depth of 4 cm could be molded without fracture using a hemispherical mold with a depth of 4 cm. B: A three-dimensional molded product with a depth of 3 cm could be molded without fracture using a hemispherical mold with a depth of 3 cm. Furthermore, when a hemispherical mold with a depth of 4 cm was used, fractures were observed in the obtained three-dimensional molded product with a depth of 4 cm, or no three-dimensional molded product with a depth of 4 cm could be obtained. C: A three-dimensional molded product with a depth of 2 cm obtained using a hemispherical mold with a depth of 2 cm had fractures.

[0143] [Examples 2 to 4, 6 to 9, Comparative Examples 1 and 2] Electromagnetic wave shielding materials were produced and various evaluations were carried out by the method described for Example 1, except that the items shown in Table 1 were changed as described in Table 1. In Comparative Example 1, in the magnetic layer formed from the prepared magnetic layer-forming composition, the solid content of the urethane resin was the value shown in the resin amount column in Table 1, where the total mass of the magnetic layer was 100 parts by mass.

[0144] Example 5 An electromagnetic wave shielding material was produced and various evaluations were performed using the same method as in Example 1, except for the following points. Instead of aluminum foil, Alpet 50-50 manufactured by Panac Corporation (a laminate formed by bonding a 50 μm-thick aluminum foil (metal layer with an Al content of 99.0% by mass or more) and a 50 μm-thick polyester film (resin layer) via a 3 μm-thick adhesive layer) was used. The obtained electromagnetic wave shielding material had a layer structure of "aluminum foil (metal layer) / adhesive layer / resin layer / magnetic layer / resin layer / adhesive layer / aluminum foil (metal layer)."

[0145] Example 10 An electromagnetic wave shielding material was produced and various evaluations were carried out in the same manner as in Example 1, except that the magnetic layer-forming composition (coating liquid) was prepared as follows.

[0146] <Preparation of Magnetic Layer Forming Composition (Coating Liquid)> The following was added to a plastic bottle: 20.0 g of Fe—Si—Al flat magnetic particles (Sendust MFS-SUH manufactured by MKT Corporation), 4.84 g of acrylic resin (see Table 1), 0.100 g of crosslinking agent (see Table 1), 0.100 g of a compound represented by Formula 1 (Starfine F-10 manufactured by Nissan Chemical Industries, Ltd.), and 57.9 g of methyl ethyl ketone. The mixture was mixed for 96 hours using a shaking stirrer to prepare a coating liquid (magnetic layer forming composition). Starfine F-10 manufactured by Nissan Chemical Industries, Ltd. is a cyanuric acid-zinc complex, and R in Formula 1 １ , R ２ and R ３ represents a hydrogen atom.

[0147] Example 11 A magnetic layer-forming composition (coating liquid) was prepared by the method described for Example 10, except that Starfine F-10 manufactured by Nissan Chemical Industries, Ltd. was replaced with VD-5 manufactured by Shikoku Chemical Industries, Ltd., which is a compound represented by formula 2. Electromagnetic wave shielding materials were otherwise produced and various evaluations were carried out by the method described for Example 1. VD-5 manufactured by Shikoku Chemical Industries, Ltd. is a compound represented by the formula 2. ４ , R ５ and R ６ Two of them are amino groups (-NH ２ ), and the other represents a 3-triethoxysilylpropylamino group (—NH—(CH ２ ) ３ -Si(OCH ２ CH ３ ) ３ ) is a compound representing

[0148]

[0149]

[0150] From the results shown in Table 2, it can be confirmed that the electromagnetic wave shielding materials of Examples 1 to 11 have excellent heat resistance and further excellent moldability.

[0151] [Example 12] A magnetic layer-forming composition (coating liquid) was prepared using the method described in Example 10. Two 50 μm thick aluminum foils (JIS H4160:2006 compliant, alloy number 1N30, temper (1) O, Al content 99.3% by mass or more) were prepared. The coating liquid was applied to one surface of each of the two aluminum foils using a blade coater with a coating gap of 300 μm, and then dried for 8 minutes in a drying device with an internal atmospheric temperature of 90°C, forming a film-like magnetic layer on each of the two aluminum foils. As a result, two multilayer partial structures ("magnetic layer / metal layer") in which a magnetic layer was sandwiched between two metal layers were prepared. The two prepared partial structures were stacked with the magnetic layers facing each other to prepare a laminate. The upper and lower press plates of a plate press (large hot press TA-200-1W manufactured by Yamamoto Iron Works) were heated to 140°C (internal temperature of the press plates), and the laminate was placed in the center of the press plates and applied with a tension of 4.66 N / mm ２ The two partial structures were thermocompression-bonded by applying a pressure of 0.05 MPa and maintaining the pressure for 15 minutes. The upper and lower press plates were cooled to 50°C (internal temperature of the press plates) while maintaining the pressure, and then the laminate was removed from the plate press. In this way, an electromagnetic wave shielding material having a layer structure of "aluminum foil (metal layer) / magnetic layer / aluminum foil (metal layer)" was obtained. Using the method previously described for the electromagnetic wave shielding material of Example 1, the thickness of the magnetic layer and the thickness of each of the two metal layers were measured at five locations. The arithmetic mean of the measurements was taken as the thickness of the magnetic layer and the thickness of each metal layer. The thickness of the magnetic layer was 30 μm, and the thickness of each metal layer was 50 μm.

[0152] [Evaluation Method] <Peel Strength> Figures 1 and 2 are explanatory diagrams for measuring peel strength. The peel strength of each electromagnetic shielding material of Example 1 and Examples 10 to 12 was measured using the following method. A measurement sample with a short side length of 2.5 cm and a long side length of 5 cm was cut from the electromagnetic shielding material of Example 1. A test aluminum foil (also simply referred to as "aluminum foil") with a short side length of 2.5 cm and a long side length of 15 cm (manufactured by Takeuchi Metal Foil & Powder Co., Ltd., model number A1N30H-O, thickness 50 μm) was prepared. One of the outermost metal layers (aluminum foil) of the measurement sample and the test aluminum foil were bonded together using instant adhesive so that one short side of each foil overlapped, creating a tension margin. This tension margin was the 10 cm long portion of the test aluminum foil where the measurement sample was not bonded (see Figure 1). The outermost metal layer (aluminum foil) of the other side of the measurement sample (i.e., the side without the tensile margin) was attached to a copper plate (manufactured by Hikari Co., Ltd., size: thickness 1 mm, short side length 5 cm, long side length 10 cm) using double-sided tape, with the measurement sample positioned at the center of the copper plate (see Figure 2). The portion of the copper plate without the electromagnetic shielding material attached was fixed to the lower chuck of the testing machine (see Figure 2). The tensile margin was then folded back 180° and fixed to the upper chuck of the testing machine, and a peel test was performed under the following measurement conditions. The peel strength calculated by dividing the measured load (unit: N (Newton)) by the short side length (2.5 cm) is shown in Table 3. The peel strength measured by the above method can be considered an index of the adhesion between two adjacent layers in a laminate. The higher the peel strength value measured by the above method, the stronger the adhesion between the adjacent metal layer and magnetic layer in the electromagnetic shielding material.From the viewpoint of high adhesion between adjacent metal layers and magnetic layers, the peel strength measured by the above method is preferably greater than 0.5 N / cm, more preferably 0.6 N / cm or greater, and even more preferably 1.0 N / cm or greater, 1.5 N / cm or greater, 2.0 N / cm or greater, 2.5 N / cm or greater, 3.0 N / cm or greater, 3.5 N / cm or greater, 4.0 N / cm or greater, and 4.5 N / cm or greater in that order. Such peel strength can be, for example, 8.0 N / cm or less, 7.5 N / m or less, or 7.0 N / cm or less. (Measurement conditions) Testing machine: Tensilon universal testing machine (RTF-1310) manufactured by A&D Co., Ltd. Measurement environment: temperature 23°C, relative humidity 50% Load cell: 500 N (Newton) Pull speed: 30 mm / min.

[0153] <Evaluation of Durability (Drop Peel Test)> A drop peel test was conducted on each of the electromagnetic shielding materials of Examples 1 and 10 to 12 in accordance with the DuPont test method described in JIS-K-5600-5-3:1999. The drop test was conducted five times from a height of 200 mm under conditions of a 6.35 mm radius for the striker and cradle, and a 300 g weight, and was evaluated according to the following criteria. "Five drop tests" means that five measurement samples cut from the electromagnetic shielding material of each Example were subjected to the drop test once for each sample (hence, a total of five tests). A: No peeling was observed in any of the five tests. B: Peeling was observed between adjacent metal layers and magnetic layers in at least one of the five tests. C: Peeling was observed between adjacent metal layers and magnetic layers in all five of the five tests.

[0154] The results are shown in Table 3. The electromagnetic wave shielding material of Example 12 was evaluated for "shielding ability before aging at 120°C" and "shielding ability after aging at 120°C" by the method described for Example 1, and both evaluation results were "A."

[0155]

[0156] The results shown in Table 3 confirm that the electromagnetic wave shielding materials of Examples 10 to 12, which contain the compound represented by Formula 1 or the compound represented by Formula 2 in the magnetic layer, have superior adhesion between the two layers, the magnetic layer and the metal layer, compared to the electromagnetic wave shielding material of Example 1.

[0157] One aspect of the present invention is useful in the technical fields of various electronic components and various electronic devices.

Claims

1. An electromagnetic wave shielding material having a magnetic layer containing magnetic particles and an acrylic resin between two metal layers, the degree of cross-linking of said magnetic layer being 20% ​​or more, and the glass transition temperature Tg of said magnetic layer being -80°C or higher.

2. The electromagnetic shielding material according to claim 1, wherein the glass transition temperature Tg of the magnetic layer is -80°C or higher and lower than 5°C.

3. The magnetic layer is represented by the following formula 1: In the formula 1, R １ , R ２ and R ３ each independently represents a hydrogen atom, an allyl group, an organic group containing a hydroxyl group, an organic group containing a carboxyl group, an organic group containing an alkoxysilyl group, or a glycidyl group.

4. The electromagnetic shielding material according to claim 3, wherein the glass transition temperature Tg of the magnetic layer is -80°C or higher and lower than 5°C.

5. The magnetic layer is formed of a compound represented by the following formula 2: In the formula 2, R ４ , R ５ and R ６ The electromagnetic shielding material according to claim 1 , wherein each independently represents an amino group or an organic group containing an alkoxysilyl group.

6. The electromagnetic shielding material according to claim 5, wherein the glass transition temperature Tg of the magnetic layer is -80°C or higher and lower than 5°C.

7. The electromagnetic shielding material according to claim 1, wherein the magnetic layer contains an acrylic resin having an alkyl (meth)acrylate structure in which the alkyl group has 2 to 8 carbon atoms.

8. The electromagnetic shielding material according to claim 1, wherein the magnetic layer contains an acrylic resin having an alkyl (meth)acrylate structure in which the alkyl group has 2 to 4 carbon atoms.

9. The electromagnetic wave shielding material according to claim 1, wherein the degree of cross-linking of said magnetic layer is 20% or more and 98% or less.

10. The electromagnetic shielding material according to claim 1, further comprising one or more layers containing a resin between the magnetic layer sandwiched between the two metal layers and one or both of the two metal layers.

11. The electromagnetic shielding material according to claim 1, wherein at least one of the metal layers has an Al content of 80.0 mass % or more.

12. The electromagnetic shielding material according to claim 1, wherein the glass transition temperature Tg of the magnetic layer is -40°C or higher and lower than -5°C.

13. The electromagnetic shielding material according to claim 1, wherein the magnetic layer contains an acrylic resin having an alkyl (meth)acrylate structure in which the alkyl group has 2 or more and 4 or less carbon atoms, the degree of cross-linking of the magnetic layer is 20% or more and 98% or less, at least one of the metal layers is a metal layer having an Al content of 80.0 mass % or more, and the glass transition temperature Tg of the magnetic layer is -40°C or more and less than -5°C.

14. The electromagnetic shielding material according to claim 13, further comprising one or more layers containing a resin between the magnetic layer sandwiched between the two metal layers and one or both of the two metal layers.

15. The magnetic layer comprises a compound represented by the following formula 1: In the formula 1, R １ , R ２ and R ３ each independently represents a hydrogen atom, an allyl group, an organic group containing a hydroxyl group, an organic group containing a carboxyl group, an organic group containing an alkoxysilyl group, or a glycidyl group.

16. The magnetic layer comprises a compound represented by the following formula 2: In the formula 2, R ４ , R ５ and R ６ Each of the groups independently represents an amino group or an organic group containing an alkoxysilyl group, 17. An electronic component comprising the electromagnetic shielding material according to any one of claims 1 to 16.

18. An electronic device comprising the electromagnetic shielding material according to any one of claims 1 to 16.

Images