WO2024004698A1

WO2024004698A1 - Electromagnetic wave shielding material, electronic component, and electronic device

Info

Publication number: WO2024004698A1
Application number: PCT/JP2023/022342
Authority: WO
Inventors: 清隆深川
Original assignee: 富士フイルム株式会社
Priority date: 2022-06-29
Filing date: 2023-06-16
Publication date: 2024-01-04

Abstract

Provided is an electromagnetic wave shielding material having one or more magnetic layers containing magnetic particles and a resin, wherein the content of the magnetic particles in the magnetic layer is more than 70 parts by mass and not more than 95 parts by mass, with the total mass of the magnetic layer being 100 parts by mass, the resin includes a urethane bond-containing resin and a diene resin, and the magnetic layer further includes a crosslinking agent. Also provided are an electronic component and an electronic device including the electromagnetic wave shielding material.

Description

Electromagnetic shielding materials, electronic components and electronic equipment

The present invention relates to electromagnetic shielding materials, electronic components, and electronic equipment.

Patent Document 1 discloses an electromagnetic shielding film that includes a magnetic layer containing a magnetic material.

JP2019-9396A

In recent years, electromagnetic shielding materials have attracted attention as materials for reducing the effects of electromagnetic waves in various electronic components and devices. Electromagnetic wave shielding materials (hereinafter also referred to as "shielding materials") have the ability to shield electromagnetic waves (hereinafter also referred to as "shielding materials") by reflecting the electromagnetic waves incident on the shielding material and/or attenuating them inside the shielding material. (Also referred to as "electromagnetic wave shielding ability" or "shielding ability.") For example, the electromagnetic shielding film described in Patent Document 1 can function as an electromagnetic shielding material.

It is desired that electromagnetic shielding materials exhibit high shielding ability. Electromagnetic shielding materials that exhibit high shielding ability against electromagnetic waves can contribute to greatly reducing the effects of electromagnetic waves in electronic components and electronic devices. However, as a result of studies conducted by the present inventors, it has been found that it is difficult for conventional electromagnetic shielding materials to exhibit high shielding ability after being placed under high temperatures.

Additionally, the performance desired for electromagnetic shielding materials includes excellent moldability. Electromagnetic shielding materials can be processed into various shapes for incorporation into electronic components or electronic equipment. Excellent moldability can mean that defects such as shape defects and breakage are unlikely to occur during molding. An electromagnetic shielding material with excellent moldability is desirable in that, for example, a molded product is unlikely to break during three-dimensional molding (in other words, three-dimensional molding).

In view of the above, an object of one embodiment of the present invention is to provide an electromagnetic shielding material that can exhibit high shielding ability after being placed under high temperature and has excellent moldability.

One aspect of the present invention is as follows.
[1] Having one or more magnetic layers containing magnetic particles and resin,
The content of the magnetic particles in the magnetic layer is more than 70 parts by mass and not more than 95 parts by mass, with the total mass of the magnetic layer being 100 parts by mass,
An electromagnetic shielding material, wherein the resin includes a urethane bond-containing resin and a diene resin, and the magnetic layer further includes a crosslinking agent.
[2] The electromagnetic wave according to [1], wherein the content of the diene resin in the magnetic layer is 2 parts by mass or more and 15 parts by mass or less, when the total content of the resin in the magnetic layer is 100 parts by mass. shield material.
[3] The electromagnetic shielding material according to [1] or [2], wherein the urethane bond-containing resin has a glass transition temperature of -60°C or more and less than 0°C.
[4] The electromagnetic shielding material according to any one of [1] to [3], wherein the crosslinking agent is a polyfunctional isocyanate.
[5] The electromagnetic shielding material according to [4], wherein the content of the polyfunctional isocyanate in the magnetic layer is 15 parts by mass or more, based on 100 parts by mass of the total content of the resin in the magnetic layer.
[6] The content of the diene resin in the magnetic layer is 2 parts by mass or more and 15 parts by mass or less, with the total content of the resin in the magnetic layer being 100 parts by mass,
The glass transition temperature of the urethane bond-containing resin is -60°C or higher and lower than 0°C,
The crosslinking agent is a polyfunctional isocyanate, and the content of the polyfunctional isocyanate in the magnetic layer is 15 parts by mass or more, based on 100 parts by mass of the total content of the resin in the magnetic layer. ] The electromagnetic shielding material described in .
[7] The electromagnetic wave shield according to any one of [1] to [6], further comprising two or more metal layers, and including one or more of the above magnetic layers sandwiched between the two metal layers. Material.
[8] An electronic component comprising the electromagnetic shielding material according to any one of [1] to [7].
[9] An electronic device comprising the electromagnetic shielding material according to any one of [1] to [7].

According to one aspect of the present invention, it is possible to provide an electromagnetic shielding material that can exhibit high shielding ability after being placed under high temperature and has excellent moldability. Further, according to one aspect of the present invention, it is possible to provide an electronic component and an electronic device including this electromagnetic shielding material.

[Electromagnetic shielding material]
One embodiment of the present invention has one or more magnetic layers containing magnetic particles and resin, and the content of the magnetic particles in the magnetic layer is more than 70 parts by mass, with the total mass of the magnetic layer being 100 parts by mass. 95 parts by mass or less, the resin includes a urethane bond-containing resin and a diene resin, and the magnetic layer further includes a crosslinking agent.

The present inventor believes that the inclusion of a diene resin in the resin of the magnetic layer contributes to improving the moldability of the electromagnetic shielding material. Further, the fact that the magnetic layer contains the urethane bond-containing resin and the crosslinking agent contributes to the electromagnetic wave shielding material being able to exhibit high shielding ability even after being placed under high temperature by increasing the heat resistance of the magnetic layer. The inventor has speculated. Further, the present inventor believes that having the content of magnetic particles in the magnetic layer within the above range contributes to improving the moldability and shielding ability of the electromagnetic shielding material. Details will be described later. However, the present invention is not limited to the speculations described in this specification.

In the present invention and this specification, an "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 field waves and electric field waves. "Electromagnetic wave shielding material" is for one or both of magnetic field waves of at least one frequency or at least a part of the frequency range, and electric field waves of at least one frequency or at least a part of the frequency range. Preferably, the material is a material that can exhibit shielding ability.

In the present invention and this specification, "magnetism" means ferromagnetic property. Details of the magnetic layer will be described later.

Hereinafter, the above electromagnetic shielding material will be explained in more detail.

<Magnetic layer>
The electromagnetic shielding material has one or more magnetic layers containing magnetic particles and resin. In one form, the electromagnetic wave shielding material can be composed of only one magnetic layer or only two or more magnetic layers, and in another form, it can include one or more of various layers described below.

(magnetic particles)
As the magnetic particles, one type selected from the group consisting of magnetic particles generally called soft magnetic particles such as metal particles and ferrite particles can be used, or two or more types can be used in combination. Since metal particles generally have a saturation magnetic flux density about 2 to 3 times that of ferrite particles, they can maintain relative magnetic permeability and exhibit shielding ability without magnetic saturation even under a strong magnetic field. Therefore, the magnetic particles contained in the magnetic layer are preferably metal particles. In the present invention and this specification, a layer containing metal particles as magnetic particles corresponds to a "magnetic layer."

Metal particles Examples of the metal particles as the magnetic particles include sendust (Fe-Si-Al alloy), permalloy (Fe-Ni alloy), molybdenum permalloy (Fe-Ni-Mo alloy), Fe-Si alloy, Fe- Examples include Cr alloys, Fe-containing alloys generally referred to as iron-based amorphous alloys, Co-containing alloys generally referred to as cobalt-based amorphous alloys, alloys generally referred to as nanocrystalline alloys, particles of iron, permendur (Fe-Co alloy), etc. . Among them, Sendust is preferred because it exhibits high saturation magnetic flux density and relative magnetic permeability. In addition to the constituent elements of metals (including alloys), metal particles include elements contained in additives that may be optionally added and/or elements contained in impurities that may be unintentionally mixed in during the manufacturing process of metal particles. may be included at any content rate. In the metal particles, the content of constituent elements of the metal (including alloys) is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, and even 100% by mass. It may be less than 100% by weight, less than 99.9% by weight, or less than 99.0% by weight.

In one form, the ability of the electromagnetic shielding material to shield against electromagnetic waves can be evaluated using the magnetic permeability (specifically, the real part of complex relative magnetic permeability) of the magnetic layer included in the electromagnetic shielding material as an index. An electromagnetic shielding material having a magnetic layer exhibiting high magnetic permeability (specifically, the real part of complex relative magnetic permeability) is preferable because it can exhibit high shielding ability against electromagnetic waves.

When complex relative magnetic permeability is measured by a magnetic permeability measurement device, a real part μ' and an imaginary part μ'' are usually displayed. In the following, the real part of the complex relative magnetic permeability at a frequency of 3 MHz (megahertz) is also simply referred to as "magnetic permeability" or "magnetic permeability μ'." Magnetic permeability can be measured by a commercially available magnetic permeability measuring device or a magnetic permeability measuring device having a known configuration. The measurement temperature is 25°C. By setting the ambient temperature of the measurement sample to the measurement temperature, temperature equilibrium is established, and the temperature of the measurement sample can be brought to the measurement temperature. From the viewpoint of exhibiting even better electromagnetic shielding ability, the magnetic permeability (real part of complex relative magnetic permeability at a frequency of 3 MHz) of the magnetic layer included in the electromagnetic shielding material is preferably 40 or more, and preferably 100 or more. More preferably, it is 120 or more. Further, the magnetic permeability can be, for example, 500 or less, 300 or less, or 200 or less, and can also exceed the values exemplified here. The above electromagnetic shielding material with high magnetic permeability is preferable because it can exhibit excellent electromagnetic shielding ability. The above magnetic permeability is the value determined for the magnetic layer before it is placed under a high temperature of 60°C or higher (excluding processes that involve heating during the manufacturing process of magnetic layers and electromagnetic shielding materials, the same shall apply hereinafter). can. Furthermore, the magnetic layer can exhibit magnetic permeability within the above range even after being placed under a high temperature of 60° C. or higher.

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 sides of the flat particles to be more parallel to the in-plane direction of the magnetic layer, the long sides of the particles are aligned in the vibration direction of the electromagnetic waves that are incident orthogonally to the electromagnetic shielding material. Since the demagnetizing field can be reduced by making the magnetic layers more aligned, the magnetic layer can exhibit higher magnetic permeability. In the present invention and this specification, "flat-shaped particles" refer to particles with an aspect ratio of 0.20 or less. The aspect ratio of the flat particles is preferably 0.15 or less, more preferably 0.10 or less. The aspect ratio of the flat particles can be, for example, 0.01 or more, 0.02 or more, or 0.03 or more. For example, the particles can be flattened by flattening using a known method. Regarding flattening, for example, the description in Japanese Patent Application Laid-Open No. 2018-131640 can be referred to, and for example, the description in paragraphs 0016 and 0017 and Examples of the same publication can be referred to. Examples of the magnetic layer exhibiting high magnetic permeability include a magnetic layer containing flat particles of sendust.

As described above, from the viewpoint of forming a layer exhibiting high magnetic permeability as a magnetic layer, it is desirable to arrange the long sides of the flat particles so that they are more parallel to the in-plane direction of the magnetic layer. is preferred. From this point of view, the degree of orientation, which is the sum of the absolute value of the average value of the orientation angle of the flat-shaped particles with respect to the surface of the magnetic layer and the variance of the orientation angle, is preferably 30° or less, and preferably 25° or less. is more preferred, still more preferably 20° or less, even more preferably 15° or less. The degree of orientation can be, for example, 3° or more, 5° or more, or 10°C or more, and can also be lower than the values exemplified here. A method for controlling the degree of orientation will be described later.

In the present invention and this specification, the aspect ratio and the above-mentioned degree of orientation of the magnetic particles are determined by the following method.
A cross section of the magnetic layer is exposed by a known method. A cross-sectional image of a randomly selected region of this cross-section is obtained as a scanning electron microscope (SEM) image. Imaging conditions are acceleration voltage: 2 kV, magnification: 1000 times, and a SEM image is obtained as a backscattered electron image.
cv2. of the image processing library OpenCV4 (manufactured by Intel). The second argument is set to 0 using the imread() function, and the second argument is read in grayscale, and the boundary is the brightness between the high brightness part and the low brightness part, and cv2. A binarized image is obtained using the threshold() function. White parts (high brightness parts) in the binarized image are identified as magnetic particles.
cv2. for the obtained binarized image. A rotating circumscribed rectangle corresponding to each magnetic particle portion is determined using the minAreaRect() function, and cv2. The long side length, short side length, and rotation angle are determined as the return values of the minAreaRect() function. When calculating the total number of magnetic particles included in the binarized image, particles of which only some of the particles are included in the binarized image are also included. For particles whose only part is included in the binarized image, the long side length, short side length, and rotation angle are determined for the part included in the binarized image. The ratio of the short side length to the long side length thus determined (short side length/long side length) is defined as the aspect ratio of each magnetic particle. In the present invention and this specification, the number of magnetic particles with an aspect ratio of 0.20 or less and identified as flat particles is 10% on a number basis with respect to the total number of magnetic particles included in the binarized image. If the above is the case, the magnetic layer is determined to be a "magnetic layer containing flat particles as magnetic particles." Further, from the rotation angle determined above, the "orientation angle" is determined as the rotation angle with respect to the horizontal plane (the surface of the magnetic layer).
Particles having an aspect ratio of 0.20 or less determined in the binarized image are identified as flat particles. The sum of the absolute value of the average value (arithmetic mean) and the variance is calculated for the orientation angles of all the flat particles included in the binarized image. The sum obtained in this way is referred to as the "degree of orientation." In addition, cv2. The coordinates of the circumscribed rectangle are calculated using the boxPoints() function and cv2. An image is created in which the rotated circumscribed rectangle is superimposed on the original image using the drawContours() function, and rotated circumscribed rectangles that are clearly erroneously detected are excluded from the calculation of the aspect ratio and degree of orientation. Further, the average value (arithmetic mean) of the aspect ratios of the particles identified as flat particles is taken as the aspect ratio of the flat particles included in the magnetic layer to be measured. Such an aspect ratio is 0.20 or less, preferably 0.15 or less, and more preferably 0.10 or less. Further, the aspect ratio can be, for example, 0.01 or more, 0.02 or more, or 0.03 or more.

From the viewpoint of improving the shielding ability of the electromagnetic shielding material, the content of magnetic particles in the magnetic layer is more than 70 parts by mass, and preferably 72 parts by mass or more, with the total mass of the magnetic layer being 100 parts by mass. More preferably, the amount is 80 parts by mass or more. Further, from the viewpoint of improving moldability and further from the viewpoint of self-supporting property of the magnetic layer, the content of magnetic particles in the magnetic layer is 95 parts by mass or less, with the total mass of the magnetic layer being 100 parts by mass, It is preferably 90 parts by mass or less, and more preferably 85 parts by mass or less. The magnetic layer may contain only one type of magnetic particle, or may contain two or more types of magnetic particles in any proportion. In the present invention and this specification, when two or more types of certain components 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 (Thermogravimetry/Differential Thermal Analysis) and extraction of various components using a solvent. Note that "TG/DTA" is generally called thermogravimetric differential thermal analysis. If the composition of the magnetic layer forming composition used to form the magnetic layer is known, the contents of various components in the magnetic layer can be determined from this known composition.

In one form, the magnetic layer can be an insulating layer. In the present invention and this specification, "insulating" means that the electrical conductivity is smaller than 1S (Siemens)/m. The electrical conductivity of a certain layer is calculated from the surface electrical resistivity of that layer and the thickness of that layer using the following formula. Electric conductivity can be measured by a known method.
Electrical conductivity [S/m] = 1/(Surface electrical resistivity [Ω] x thickness [m])

The present inventor conjectures that it is preferable that the magnetic layer is an insulating layer so that the electromagnetic shielding material exhibits even higher electromagnetic shielding ability. From this point of view, the electrical conductivity of the magnetic layer is preferably smaller 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 0.5 S/m or less. More preferably, it is .05 S/m or less. The electrical conductivity of the magnetic layer can be, for example, 1.0×10 ⁻¹² S/m or more or 1.0×10 ⁻¹⁰ S/m or more.

(resin)
The magnetic layer is a layer containing magnetic particles and resin. The resin can serve as a binder in the magnetic layer. In the present invention and this specification, a layer containing both magnetic particles and resin corresponds to a "magnetic layer". The total content of resin in the magnetic layer is 5 parts by mass or more, with the total mass of the magnetic layer being 100 parts by mass, from the viewpoint of further improving moldability and further from the viewpoint of self-supporting property of the magnetic layer. The amount is preferably 10 parts by mass or more, more preferably 15 parts by mass or more. Further, from the viewpoint of further improving the shielding ability of the electromagnetic shielding material, the total content of the resin in the magnetic layer is preferably less than 30 parts by mass, and 28 parts by mass, with the total mass of the magnetic layer being 100 parts by mass. It is more preferably at most 25 parts by mass, even more preferably at most 20 parts by mass.

In the present invention and this specification, "resin" means a polymer, and includes rubber and elastomer. Polymers include homopolymers and copolymers. Rubber includes natural rubber and synthetic rubber. Moreover, an elastomer is a polymer that exhibits elastic deformation.

The magnetic layer of the electromagnetic shielding material includes a urethane bond-containing resin and a diene resin. The present inventor believes that the crosslinking reaction of the urethane bond-containing resin with the crosslinking agent contributes to improving the heat resistance of the magnetic layer. The present inventor conjectures that this contributes to the ability of the electromagnetic shielding material to exhibit high shielding ability even after being placed under high temperatures. Further, the present inventor believes that the diene resin contributes to improving the moldability of the electromagnetic shielding material. The present inventor conjectures that this is because the diene resin can provide the magnetic layer with elongation properties suitable for molding.

In the present invention and this specification, "urethane bond-containing resin" refers to a resin containing one or more urethane bonds (-NH-C(=O)O-) in one molecule. The urethane bond-containing resin includes various urethane bond-containing resins such as polyurethane resin, polyester urethane resin, and polyurethane elastomer. In the magnetic layer, one type of urethane bond-containing resin may be used alone, or two or more types may be used in combination. The type of resin contained in the magnetic layer can be determined by, for example, organic analysis such as pyrolysis GC/MS (Gas Chromatography/Mass Spectrometry) and Fourier Transform Infrared Spectroscopy. For example, if isocyanate component residues and/or polyol component residues are observed by thermal decomposition GC/MS, it can be determined that the resin is a urethane bond-containing resin.

From the viewpoint of further improving the moldability of the electromagnetic shielding material, the glass transition temperature Tg of the urethane bonding resin contained in the magnetic layer is preferably less than 0°C. In the present invention and this specification, the glass transition temperature Tg of the resin is determined from the measurement results of heat flow measurement using a differential scanning calorimeter as the baseline shift start temperature of the heat flow chart during temperature rise. From the viewpoint of further improving the moldability of the electromagnetic shielding material, the glass transition temperature Tg of the urethane bond-containing resin contained in the magnetic layer is preferably -3°C or lower, and preferably -5°C or lower. More preferably, the temperature is -10°C or lower, -20°C or lower, -30°C or lower, and -40°C or lower in this order. Further, the glass transition temperature Tg of the urethane bond-containing resin contained in the magnetic layer can be, for example, -100°C or higher, -90°C or higher, -80°C or higher, -70°C or higher, or -60°C or higher. .

In the present invention and this specification, "diene-based resin" refers to a resin having a diene polymer structure in the molecule. Since diene resins can generally exhibit rubber elasticity, they are thought to be able to impart extensibility to the magnetic layer. It is presumed that this contributes to improving the formability of the electromagnetic shielding material. Examples of the diene resin include natural rubber (NR), isoprene rubber (IR), acrylonitrile-butadiene rubber (NBR), and styrene-butadiene rubber (SBR). ne-Butadiene Rubber ), ethylene-propylene rubber (binary polymer of ethylene and propylene rubber (EPM: Ethylene Propylene Rubber)), terpolymer containing ethylene and propylene rubber (EPDM: Ethylene Propylene Diene Methylene Lin) kage), butyl rubber (IIR), butyl rubber (IIR) -Isoprene Rubber), copolymer of isobutylene and aromatic vinyl or diene monomer, brominated butyl rubber (Br-IIR), chlorinated butyl rubber (Cl-IIR), isobutylene-paramethyl rubber With tyrene Examples include polymer bromide (BIMS: Brominated isobutylene-paramethylstyrene), chloroprene rubber (CR), and the like. These diene resins may be used alone or in combination of two or more types in the magnetic layer. Furthermore, hydrogenated products of these diene resins can also be used.

The resin contained in the magnetic layer may be only a urethane bond-containing resin and a diene resin, or it may contain an arbitrary amount of one or more other resins in addition to the urethane bond-containing resin and diene resin. It may be The total content of the urethane bond-containing resin and diene resin based on 100 parts by mass of the total amount of resin in the magnetic layer may be, for example, 80 parts by mass or more, 85 parts by mass or more, 90 parts by mass or more, or 95 parts by mass or more. It can also be 100 parts by weight, or less than 100 parts by weight, less than 100 parts by weight, less than 99 parts by weight, or less than 98 parts by weight.

The content of the diene resin in the magnetic layer may be 2 parts by mass or more, based on a total content of resin in the magnetic layer of 100 parts by mass, from the viewpoint of further improving the moldability of the electromagnetic shielding material. It is preferably 5 parts by mass or more, more preferably 10 parts by mass or more. Further, the content of the diene resin in the magnetic layer is, for example, 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, or 20 parts by mass or less, with the total content of resin in the magnetic layer being 100 parts by mass. From the viewpoint of further improving the moldability of the electromagnetic shielding material, the amount is preferably 15 parts by mass or less.

(Crosslinking agent)
The magnetic layer includes at least magnetic particles, a urethane bond-containing resin, and a diene resin, and further includes a crosslinking agent. In the present invention and this specification, the term "crosslinking agent" refers to a compound having a crosslinkable group. In the present invention and this specification, the term "crosslinkable group" refers to a group that can undergo a crosslinking reaction. In the magnetic layer containing a crosslinking agent, the crosslinking agent may be contained in a form after at least some of the crosslinkable groups have undergone a crosslinking reaction. As the crosslinking agent, a compound having two or more crosslinkable groups (for example, two or more and four or less) in one molecule is preferable. In one form, the content of the crosslinking agent in the magnetic layer can be, for example, 1 part by mass or more, when the total content of the resin in the magnetic layer is 100 parts by mass, and the electromagnetic shielding material is placed under high temperature. From the viewpoint of further suppressing the deterioration of the shielding ability after drying, the preferred amounts are 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, and 20 parts by mass or more. Further, in one embodiment, when the total content of resin in the magnetic layer is 100 parts by mass, the magnetic layer can contain 100 parts by mass or less or 40 parts by mass or less of a crosslinking agent. From the viewpoint of further improving moldability, the content of the crosslinking agent in the magnetic layer is preferably 30 parts by mass or less, and 25 parts by mass, assuming the total resin content in the magnetic layer is 100 parts by mass. It is more preferably at most 23 parts by mass, and even more preferably at most 23 parts by mass.

A specific example of the crosslinkable group is an isocyanate group, and a specific example of the crosslinking agent is a polyfunctional isocyanate. A polyfunctional isocyanate is a compound having two or more (eg, two, three, or four) isocyanate groups in one molecule. In one form, when the total content of the resin in the magnetic layer is 100 parts by mass, the content of the polyfunctional isocyanate in the magnetic layer can be, for example, 1 part by mass or more, and the electromagnetic shielding material can be used at high temperatures. From the viewpoint of further suppressing the decline in shielding ability after being placed, the preferred amounts are 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, and 20 parts by mass or more. Further, in one embodiment, the magnetic layer may contain 100 parts by mass or less or 40 parts by mass or less of a polyfunctional isocyanate, when the total content of resin in the magnetic layer is 100 parts by mass. From the viewpoint of further improving moldability, the content of polyfunctional isocyanate in the magnetic layer is preferably 30 parts by mass or less, with the total content of resin in the magnetic layer being 100 parts by mass, and 25 parts by mass or less. It is more preferably at most 23 parts by mass, even more preferably at most 23 parts by mass.

In addition to the above-mentioned components, the magnetic layer can also contain one or more types of known additives such as dispersants, stabilizers, and coupling agents in arbitrary amounts.

The electromagnetic wave shielding material includes at least one magnetic layer, more specifically, it may include only one magnetic layer, or it may include two or more magnetic layers having the same or different compositions and/or thicknesses. can.
When the electromagnetic wave shielding material includes only one magnetic layer, the thickness of this single magnetic layer can be, for example, 5 μm or more, and from the viewpoint of further improving the shielding ability against electromagnetic waves, the thickness is 10 μm or more. The thickness is preferably 20 μm or more, and more preferably 20 μm or more. Further, the thickness of this single magnetic layer can be, for example, 100 μm or less or 90 μm or less, and from the viewpoint of further improving moldability, it is preferably less than 90 μm, and more preferably 80 μm or less. It is preferably 70 μm or less, and more preferably 70 μm or less.
When the electromagnetic wave shielding material includes two or more of the magnetic layers, the thickness of each of the two or more magnetic layers (i.e., the thickness per layer) can be, for example, 5 μm or more, and the shielding ability against electromagnetic waves is reduced. From the viewpoint of further improvement, it is preferably 10 μm or more, more preferably 20 μm or more. Further, the thickness of this single magnetic layer can be, for example, 100 μm or less or 90 μm or less, and from the viewpoint of further improving moldability, it is preferably less than 90 μm, and more preferably 80 μm or less. preferable. The thicknesses of two or more magnetic layers can be the same or different.

The thickness of each layer included in the electromagnetic shielding material is determined by imaging a cross section exposed using a known method using a scanning electron microscope (SEM), and measuring the thickness of five randomly selected locations in the obtained SEM image. shall be determined as the arithmetic mean of

In one form, the electromagnetic shielding material can be composed of only the single magnetic layer, and in another form, it can include one or more magnetic layers and one or more other layers. Below, various layers that may be included in the electromagnetic shielding material will be explained.

<Adhesive layer>
The electromagnetic shielding material may include one or more adhesive layers. In the above electromagnetic shielding material, at least one adhesive layer may be located as a layer directly in contact with the magnetic layer. In the present invention and this specification, "directly contacting" with respect to two layers means that no other layer is interposed between these two layers. Furthermore, in the present invention and this specification, the term "adhesive layer" refers to a layer that has tackiness on its surface at room temperature. Here, "normal temperature" refers to 23°C. When such a layer comes into contact with an adherend, it adheres to the adherend due to its adhesive force. Tackiness generally refers to the property of exhibiting adhesive strength in a short time after contacting an adherend with a very light force, and in the present invention and this specification, "having tackiness" is defined as In the tilted ball tack test (measurement environment: temperature 23°C, relative humidity 50%) specified in Z0237:2009, the result was No. 1~No. It means that it is 32. When another layer is laminated on the surface of the adhesive layer, for example, the surface of the adhesive layer exposed by peeling off the other layer can be subjected to the above test. When other layers are laminated on one surface and the other surface of the adhesive layer, the other layer on either surface side may be peeled off.

In one form, the glass transition temperature Tg of the adhesive layer can be, for example, less than 50°C, 45°C or less, or 40°C or less, and can be, for example, -70°C or more. The glass transition temperature Tg of the adhesive layer is determined from the measurement results of heat flow measurement using a differential scanning calorimeter, as the intermediate temperature between the start point and end point of the fall on a DSC (differential scanning calorimetry) chart.

As the adhesive layer, use a film 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. Can be done.
The composition for forming an adhesive layer can also be applied onto a support, for example. Coating can be performed using a known coating device such as a blade coater or die coater. Application can be carried out in a so-called roll-to-roll manner or in a batch manner.
Examples of the support to which the composition for forming an adhesive layer is applied include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylics such as polycarbonate (PC) and polymethyl methacrylate (PMMA), and cyclic polyolefins. , triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. As the support, a support whose surface to which the composition for forming an adhesive layer is applied (coating surface) has been subjected to a release treatment by a known method can be used. One form of peeling treatment includes forming a release layer. Moreover, a commercially available peel-treated resin film can also be used as the support. By using a support whose coated surface has been subjected to a release treatment, the adhesive layer and the support can be easily separated after film formation.
An electromagnetic shielding material in which a magnetic layer and an adhesive layer are laminated can also be produced by applying an adhesive layer forming composition in which an adhesive is dissolved and/or dispersed in a solvent to a magnetic layer and drying the composition.

An adhesive tape containing an adhesive layer can also be used to produce an electromagnetic shielding material having an adhesive layer. Double-sided tape can be used as the adhesive tape. Double-sided tape has adhesive layers on both sides of a support, and each of the adhesive layers on both sides can have tackiness at room temperature. Further, as the adhesive tape, an adhesive tape having an adhesive layer on one side of a support can also be used. Examples of the support include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylics such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), and polyethers. Examples include films of various resins such as sulfide (PES), polyether ketone, and polyimide, nonwoven fabrics, and paper. As the adhesive tape having an adhesive layer disposed on one or both sides of the support, commercially available products can be used, and double-sided tapes prepared by known methods can also be used.

The above-mentioned electromagnetic wave shielding material can have one or more adhesive layers, more specifically, it can have only one adhesive layer, and it can also have two or more adhesive layers with the same or different composition and/or thickness. can. The total number of adhesive layers included in the electromagnetic shielding material can be, for example, one to four layers, one layer, or two layers.
When the electromagnetic shielding material includes only one adhesive layer, the thickness of this single adhesive layer can be, for example, 0.5 μm or more, preferably 1 μm or more, and more preferably 2 μm or more. preferable. Further, the thickness of this single adhesive layer can be, for example, 20 μm or less or 10 μm or less.
When the electromagnetic shielding material includes two or more adhesive layers, the thickness of each of these two or more adhesive layers (i.e., the thickness per layer) can be, for example, 0.5 μm or more, and 0.8 μm or more. It is preferable that it is, and it is more preferable that it is 1.5 μm or more. Further, the thickness of this single adhesive layer can be, for example, 10 μm or less or 5 μm or less. The thicknesses of two or more adhesive layers can be the same or different.

In one form, the electromagnetic shielding material can be an electromagnetic shielding material composed of two layers: one magnetic layer and one adhesive layer. In another form, the electromagnetic shielding material may be configured of three layers: a magnetic layer, an adhesive layer, and a magnetic layer, and may include these three layers in this order. In another form, the electromagnetic shielding material may include a resin layer between two adhesive layers. For example, the electromagnetic shielding material may include the magnetic layer and a laminated structure having a resin layer between two adhesive layers. In a laminated structure having a resin layer between two adhesive layers, the resin layer can be a layer that is in direct contact with one or both of the two adhesive layers, and must be a layer that is in direct contact with both adhesive layers. is preferred. In one form, the electromagnetic shielding material may be configured of four layers: a magnetic layer, an adhesive layer, a resin layer, and an adhesive layer, and may include these four layers in this order. In another form, the electromagnetic shielding material may have a laminated structure having a resin layer between two adhesive layers on both sides of the magnetic layer. An example of an electromagnetic shielding material having such a structure is an electromagnetic shielding material that is composed of seven layers: an adhesive layer, a resin layer, an adhesive layer, a magnetic layer, an adhesive layer, a resin layer, and an adhesive layer, and includes these seven layers in this order. can. In another embodiment, the electromagnetic shielding material may further include a metal layer, which will be described later, in each of the layered structures.

<Resin layer>
The electromagnetic shielding material described above can also have a resin layer between the two adhesive layers. In the present invention and this specification, a "resin layer" refers to a layer containing a resin, and can be a layer containing resin as a main component. The main component refers to the component that occupies the largest amount on a mass basis among the components constituting the layer. The content of the resin in the resin layer is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, and still more preferably 90 parts by mass or more, based on the total mass of the resin layer as 100 parts by mass. preferable. Further, the content of the resin in the resin layer can be, for example, 100 parts by mass or less, less than 100 parts by mass, or 99 parts by mass or less, with the total mass of the resin layer being 100 parts by mass. The resin layer contains one or more resins, and may also contain one or more known additives such as plasticizers, crosslinking agents, dispersants, stabilizers, and coupling agents in arbitrary amounts in addition to the resins. can.

As the resin layer, for example, a commercially available resin film that can be used as a plastic base material, a resin film manufactured by a known method, etc. can be used. Examples of the resin contained in the resin layer include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, cellophane, diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, polyvinyl chloride, polyvinylidene chloride, and polyvinyl Alcohol, ethylene-vinyl acetate copolymer, polystyrene, polycarbonate, polymethylpentene, polysulfone, polyetheretherketone, polyethersulfone, polyetherimide, polyimide, fluororesin, nylon, acrylic resin, polyamide, cycloolefin, polyether Examples include resins such as sulfan. Among these, resin films such as polyethylene terephthalate, polyethylene naphthalate, and nylon are preferred because of their high mechanical strength. One form of the resin layer is a support for the double-sided tape.
The thickness of the resin layer is preferably 0.1 μm or more, more preferably 1 μm or more. Further, the thickness of the resin layer is preferably, for example, 100 μm or less, more preferably 10 μm or less, and even more preferably less than 10 μm. The electromagnetic shielding material may include only one resin layer disposed between two adhesive layers, or may include two or more layers (for example, two or three layers).

The glass transition temperature Tg of the resin layer can be, for example, 50°C or higher, 60°C or higher, or 70°C or higher, and, for example, 150°C or lower, 130°C or lower, or 110°C or lower. Can be done. The glass transition temperature Tg of the resin layer is determined from the measurement results of heat flow measurement using a differential scanning calorimeter as the intermediate temperature between the start point and the end point of the fall on a DSC (differential scanning calorimetry) chart.

<Metal layer>
In the present invention and this specification, a "metal layer" refers to a layer containing metal. A metal layer is a layer containing one or more metals, either as a pure metal consisting of a single metal element, as an alloy of two or more metal elements, or as an alloy of one or more metal elements and one or more non-metal elements. can be.

The electromagnetic shielding material may further include one or more metal layers. In one form, the two or more metal layers have the same composition and thickness, and in another form, they have different compositions and/or thicknesses. In an electromagnetic shielding material including two or more metal layers, one or more magnetic layers may be placed at a position sandwiched between two metal layers. Here, the magnetic layer sandwiched between the two metal layers may be a layer that is in direct contact with one or both of the two metal layers, or may be a layer that is in direct contact with one or both of the two metal layers, or may be a layer that is in direct contact with one or more other layers (e.g., an adhesive layer). It can be a layer that is in indirect contact with the other layer via the layer. The metal layer can be, for example, the outermost layer of one or both of the electromagnetic shielding materials. Further, in one form, the electromagnetic shielding material has a metal layer, the laminated structure (i.e., a laminated structure having a resin layer between two adhesive layers), a magnetic layer, the laminated structure, and a metal layer in this order. Can be done. In this embodiment, the electromagnetic wave shielding material is composed of nine layers, for example, a metal layer, an adhesive layer, a resin layer, an adhesive layer, a magnetic layer, an adhesive layer, a resin layer, an adhesive layer, and a metal layer. It can be an electromagnetic shielding material containing in this order. Further, a metal layer, the above-mentioned laminate structure (that is, a laminate structure having a resin layer between two adhesive layers), a magnetic layer, the above-mentioned laminate structure, a metal layer, the above-mentioned laminate structure, a magnetic layer, the above-mentioned laminate structure, and a metal layer. , in this order. In this embodiment, the electromagnetic wave shielding material includes, for example, a metal layer, an adhesive layer, a resin layer, an adhesive layer, a magnetic layer, an adhesive layer, a resin layer, an adhesive layer, a metal layer, an adhesive layer, a resin layer, an adhesive layer, a magnetic layer. , an adhesive layer, a resin layer, an adhesive layer, and a metal layer, and can be an electromagnetic shielding material including these 17 layers in this order. A structure in which the magnetic layer is sandwiched between two metal layers is preferable from the viewpoint of improving shielding ability against magnetic field waves having a frequency in the range of 0.01 to 100 MHz.

As the metal layer, a layer containing one or more metals selected from the group consisting of various pure metals and various alloys can be used. The metal layer can exert a damping effect in the shielding material. The larger the propagation constant is, the larger the attenuation effect is, and the larger the electrical conductivity is, the larger the propagation constant is. Therefore, the metal layer preferably contains a metal element with high electrical conductivity. From this point of view, it is preferable that the metal layer contains 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 metallic element and may contain trace amounts of impurities. Generally, a metal consisting of a single metal element and having a purity of 99.0% or more is called a pure metal. Purity is by weight. Alloys are generally made by adding one or more metallic elements or non-metallic elements to a pure metal to adjust the composition in order to prevent corrosion, improve strength, etc. The main component in an alloy is a component having the highest proportion on a mass basis, and can be, for example, a component that accounts for 80.0% by mass or more (for example, less than 100% by mass or 99.8% by mass or less) in the alloy. From the economic point of view, pure metals such as Cu or Al or alloys mainly composed of Cu or Al are preferred, and from the viewpoint of high electrical conductivity, pure metals such as Cu or alloys mainly composed of Cu are more preferred.

The metal purity in the metal layer, that is, the metal content can be 99.0% by mass or more, preferably 99.5% by mass or more, and 99.8% by mass or more, based on the total mass of the metal layer. More preferably, it is at least % by mass. The content of metal in the metal layer is based on mass unless otherwise specified. For example, a pure metal or an alloy processed into a sheet can be used as the metal layer. For example, as the metal layer, a commercially available metal foil or a metal foil produced by a known method can be used. Regarding pure metal Cu, sheets (so-called copper foils) of various thicknesses are commercially available. For example, such copper foil can be used as a metal layer. There are two types of copper foil: electrolytic copper foil, which is obtained by depositing copper foil on a cathode by electroplating, and rolled copper foil, which is obtained by applying heat and pressure to an ingot and stretching it thin. Any copper foil can be used as the metal layer of the electromagnetic shielding material. Furthermore, for example, sheets of Al (so-called aluminum foil) of various thicknesses are commercially available. For example, such aluminum foil can be used as the metal layer.

From the viewpoint of reducing the weight of the electromagnetic shielding material, one or both (preferably both) of the two metal layers included in the multilayer structure are metal layers containing a metal selected from the group consisting of Al and Mg. It is preferable that there be. This is because both Al and Mg have a small value obtained by dividing specific gravity by electrical conductivity (specific gravity/electrical conductivity). The smaller this value is used, the lighter the electromagnetic shielding material that exhibits high shielding ability can be made. As a value calculated from literature values, for example, the value obtained by dividing the specific gravity by the electrical conductivity of Cu, Al, and Mg (specific gravity/electrical conductivity) is as follows. Cu: 1.5×10 ⁻⁷ m/S, Al: 7.6×10 ⁻⁸ m/S, Mg: 7.6×10 ⁻⁸ m/S. From the above values, it can be said that Al and Mg are preferable metals from the viewpoint of reducing the weight of the electromagnetic shielding material. A metal layer containing a metal selected from the group consisting of Al and Mg can include only one of Al and Mg in one form, and can contain both of Al and Mg in another form. From the viewpoint of reducing the weight of the electromagnetic shielding material, one or both (preferably both) of the two metal layers included in the multilayer structure have a content rate of 80% of the metal selected from the group consisting of Al and Mg. It is more preferable that the metal layer has a content of .0% by mass or more, and it is even more preferable that the metal layer has a content of a metal selected from the group consisting of Al and Mg of 90.0% by mass or more. The metal layer containing at least Al among Al and Mg can be a metal layer with an Al content of 80.0% by mass or more, and can also be a metal layer with an Al content of 90.0% by mass or more. can. The metal layer containing at least Mg among Al and Mg can be a metal layer with an Mg content of 80.0% by mass or more, and can also be a metal layer with an Mg content of 90.0% by mass or more. can. The content of the metal selected from the group consisting of Al and Mg, the Al content, and the Mg content can be, for example, less than 100% by mass or 99.9% by mass or less, respectively. The content rate of the metal selected from the group consisting of Al and Mg, the Al content rate, and the Mg content rate are each based on the total mass of the metal layer.

<Method for manufacturing electromagnetic shielding material>
(Method of forming magnetic layer)
The above-mentioned magnetic layer can be produced, for example, by applying a magnetic layer-forming composition and drying a coated layer. The composition for forming a magnetic layer contains the components described above, and can optionally contain one or more solvents. Examples of solvents include various organic solvents, such as ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone, acetate ester solvents such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate, cellosolve, and butyl carbide. Examples include carbitols such as toll, aromatic hydrocarbon solvents such as toluene and xylene, and amide solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. One type of solvent selected in consideration of the solubility of the components used in preparing the composition for forming a magnetic layer, or a mixture of two or more types of solvents in any ratio can be used. The solvent content of the composition for forming a magnetic layer is not particularly limited, and may be determined by taking into consideration the applicability of the composition for forming a magnetic layer.

The composition for forming a magnetic layer can be prepared by sequentially mixing various components in any order or by mixing them simultaneously. Further, if necessary, dispersion treatment can be performed using a known dispersion machine such as a ball mill, bead mill, sand mill, or roll mill, and/or stirring using a known agitator such as a shaking type stirrer. Processing can also be performed.

The composition for forming a magnetic layer can be applied onto a support, for example. Coating can be performed using a known coating device such as a blade coater or die coater. Application can be carried out in a so-called roll-to-roll manner or in a batch manner.

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

In one form, the composition for forming a magnetic layer is applied onto the adhesive layer using the adhesive layer as a support, an adhesive tape having an adhesive layer as a support, or a laminated structure having a resin layer between two layers as a support. Alternatively, it is also possible to apply directly onto the adhesive layer of the above-mentioned laminated structure.

The coating layer formed by applying the composition for forming a magnetic layer can be subjected to a drying treatment by a known method such as heating or blowing hot air. The drying treatment can be carried out under conditions that allow the solvent contained in the magnetic layer forming composition to be volatilized, for example. As an example, the drying process can be performed in a heated atmosphere at an ambient temperature of 80 to 150° C. for 1 minute to 2 hours.

Regarding the magnetic layer forming composition containing a crosslinking agent in addition to magnetic particles and resin, the above description can be referred to regarding the crosslinking agent. A magnetic layer formed using such a composition for forming a magnetic layer can be subjected to crosslinking treatment using a crosslinking agent at any stage. As the crosslinking treatment, heat treatment or light irradiation treatment can be performed depending on the type of crosslinking agent. For example, when the crosslinking treatment is a heat treatment, such heat treatment can be performed before the pressure treatment described below in one form, and after the pressure treatment described below in another form. According to studies conducted by the present inventors, it has been found that when the heat treatment is performed after the pressure treatment, the magnetic permeability of the formed magnetic layer tends to increase. The above heat treatment can be performed, for example, by maintaining the magnetic layer before or after the pressure treatment in an environment with an ambient temperature of 35° C. or higher (for example, 35° C. or higher and 150° C. or lower). The holding time can be, for example, 3 to 72 hours.

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 composition for forming a magnetic layer. For example, if the boiling point of the solvent is low, the value of the degree of orientation tends to increase due to convection caused by drying. When the amount of solvent is small, the value of the degree of orientation tends to increase due to physical interference between adjacent flat particles. On the other hand, when the liquid viscosity is low, rotation of the flat particles tends to occur, so the value of the degree of orientation tends to be small. As the coating thickness decreases, the value of the degree of orientation tends to decrease. Furthermore, performing the pressure treatment described below can contribute to reducing the value of 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.

(Pressure treatment of magnetic layer)
The magnetic layer can also be subjected to pressure treatment after film formation. By pressurizing the magnetic layer containing magnetic particles, the density of the magnetic particles in the magnetic layer can be increased, and higher magnetic permeability can be obtained. In addition, the magnetic layer containing flat particles can have a lower degree of orientation by pressure treatment, and can obtain higher magnetic permeability.

The pressure treatment can be performed by applying pressure in the thickness direction of the magnetic layer using a plate press, a roll press, or the like. A plate press machine places an object to be pressed between two flat press plates arranged above and below, and applies pressure to the object by bringing the two press plates together using mechanical or hydraulic pressure. Can be done. A roll press machine passes a pressurized object between rotating pressure rolls arranged above and below, and at this time, mechanical or hydraulic pressure is applied to the pressure rolls, or the distance between the pressure rolls is adjusted to Pressure can be applied by making the thickness smaller than .

The pressure during the pressure treatment can be set arbitrarily. For example, in the case of a plate press, the pressure is, for example, 1 to 50 N (Newton)/mm ² . In the case of a roll press machine, the linear pressure is, for example, 20 to 400 N/mm.
The pressurization time can be set arbitrarily. When using a plate press, the time is, for example, 5 seconds to 4 hours. When using a roll press machine, the pressing time can be controlled by the conveyance speed of the object to be pressed, for example, the conveyance speed is 10 cm/min to 200 m/min.
The material of the press plate and pressure roll can be arbitrarily selected from metal, ceramics, plastic, rubber, etc.
During the pressure treatment, it is also possible to carry out the heat and pressure treatment by, for example, applying heat to both or one of the upper and lower press plates of a plate-shaped press, or to one of the upper and lower rolls of a roll press. In the heat and pressure treatment, the magnetic layer can be softened by heating, and thereby a high compression effect can be obtained when pressure is applied. The temperature during heating can be set arbitrarily, and is, for example, 50° C. or higher and 200° C. or lower. The temperature during the above heating can be the internal temperature of the press plate or roll. Such temperature can be measured by a thermometer placed inside the press plate or roll. In one form, heat treatment can be performed as a crosslinking agent curing treatment before or after the heating and pressure treatment. Such heat treatment is as described above.
After the heat and pressure treatment in the plate press, the magnetic layer can be taken out by separating the press plate while the temperature of the press plate is high, for example. Alternatively, the press plate may be cooled by water cooling, air cooling, or the like while the pressure is maintained, and then the press plate may be separated to take out the magnetic layer.
In a roll press machine, 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 a magnetic layer is formed on a release film, it can be subjected to pressure treatment while being laminated on the release film, for example. Alternatively, the magnetic layer can be pressure-treated as a single layer after being peeled off from a release film.

(Lamination of various layers)
As described above, the adhesive layer can be attached to the magnetic layer in the form of an adhesive tape, or can be laminated with the magnetic layer by applying an adhesive layer-forming composition to the magnetic layer and drying it.
The metal layer can be incorporated into the electromagnetic shielding material as a layer that is in direct contact with the adhesive layer, for example by bonding it with the adhesive layer.
Further, in the electromagnetic shielding material described above, two adjacent layers can be bonded together by applying pressure and heat, for example. For crimping, a plate press machine, a roll press machine, etc. can be used. For example, when a magnetic layer is arranged as a layer in direct contact with a metal layer, the two adjacent layers can be bonded together by softening the magnetic layer in the compression bonding process and promoting contact with the surface of the metal layer. The pressure during crimping can be set arbitrarily. In the case of a plate press, it is, for example, 1 to 50 N/mm ² . In the case of a roll press machine, the linear pressure is, for example, 20 to 400 N/mm. The pressurizing time during crimping can be set arbitrarily. When using a plate press, the time is, for example, 5 seconds to 30 minutes. When using a roll press machine, the conveyance speed of the pressurized object can be controlled, for example, the conveyance speed is 10 cm/min to 200 m/min. The temperature during pressure bonding can be arbitrarily selected, and is, for example, 20° C. or more and 200° C. or less. The above-mentioned temperature during pressure bonding can be, for example, the internal temperature of the press plate or roll.

The electromagnetic shielding material described above can be incorporated into electronic components or electronic equipment in any shape. The electromagnetic shielding material may be in the form of a sheet, and its size is not particularly limited. In the present invention and this specification, "sheet" is synonymous with "film". Further, the electromagnetic shielding material may be a three-dimensional molded product obtained by three-dimensionally molding a sheet-like electromagnetic shielding material, or a sheet-like electromagnetic shielding material for three-dimensional molding. As the three-dimensional molding method, various molding methods such as die press molding, vacuum molding, and pressure molding can be used. Regarding the molding method, molding performed without heating the molding object and/or the mold, or by heating without raising the temperature too much, is generally referred to as cold molding. The above-mentioned electromagnetic shielding material can exhibit excellent formability in cold forming. Therefore, the electromagnetic shielding material described above is suitable for cold forming such as drawing and stretch forming. Draw forming is a forming method in which a sheet-shaped object is pressed using a pair of female and male molds to form containers with bottoms of various shapes such as cylinders, square tubes, cones, etc. be. On the other hand, stretch molding is a method of molding a molded product with a curved surface extending from a flat surface from a sheet-like molded object. Stretch molding can also be carried out using a press using only a male die without a female die. Drawing forming is roughly divided into deep drawing forming and shallow drawing forming. Shallow drawing forms a molded product with a shallow depth, and deep drawing forms a molded product with a deep depth (for example, the depth is deeper than the diameter of a cylinder or cone or the length of one side of a pyramid). The electromagnetic shielding material may be an electromagnetic shielding material that is difficult to break when molded by such three-dimensional molding method. As for the three-dimensional molding method, known techniques can be applied.

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

[Electronics]
One aspect of the present invention relates to an electronic device including the electromagnetic shielding material described above. The above-mentioned electronic devices include electronic devices such as mobile phones, personal digital assistants, and medical equipment, electronic devices that include various electronic components such as semiconductor elements, capacitors, coils, and cables, and electronic devices that have electronic components mounted on circuit boards. can be mentioned. Such an electronic device can include the electromagnetic shielding material described above as a constituent member of an electronic component included in the device. Further, as a component of an electronic device, the electromagnetic shielding material can be placed inside the electronic device, or can be placed as a cover material covering the outside of the electronic device. Alternatively, it can be three-dimensionally molded into a cylindrical shape and placed as a cover material that covers the outside of the cable.

An example of how the electromagnetic shielding material is used is in which a semiconductor package on a printed circuit board is covered with the shielding material. For example, in "Electromagnetic Shielding Technology for Semiconductor Packages" (Toshiba Review Vol. 67 No. 2 (2012) P. 8), when covering a semiconductor package with a shielding material, the side vias at the edge of the package substrate and the shielding material A method is disclosed in which a high shielding effect is obtained by performing ground wiring by electrically connecting the inner surface. In order to perform such wiring, it is desirable that the outermost layer of the shield material on the electronic component side is a metal layer. In one form, the electromagnetic shielding material described above can have one or both outermost layers of the shielding material being a metal layer, and thus can be suitably used when wiring as described above.

Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to the embodiments shown in Examples.

[Resin of magnetic layer]
The resins of the magnetic layer shown in Table 1 are as follows. In Table 1, polyurethane resin is expressed as "polyurethane," polyester urethane resin is expressed as "polyester urethane," and acrylonitrile-butadiene rubber is expressed as "NBR."
The polyurethane resin having a glass transition temperature Tg of −50° C. is Nipporan 5120 manufactured by Tosoh Corporation.
The polyester urethane resin having a glass transition temperature Tg of -3°C is UR-3200 manufactured by Toyobo Co., Ltd.
The polyester urethane resin having a glass transition temperature Tg of 23° C. is UR-8300 manufactured by Toyobo Co., Ltd.
The acrylonitrile-butadiene rubber is Nipol model number DN003 manufactured by Nippon Zeon.

The glass transition temperatures of the resins shown in Table 1 are values determined by the following method.
The same resin (pellet or powder sample) used to prepare the magnetic layer forming composition (coating solution) was placed in an aluminum sample pan, sealed using a press, and then used as a differential scanning calorimeter. - Heat flow measurement was performed using Instrument Q100 under the following conditions. From the measurement results, the glass transition temperature of the resin was determined as the baseline shift start temperature of the heat flow chart during temperature rise.
(Measurement condition)
Scanning temperature: -80.0℃~200.0℃
Heating rate: 10.0℃/min

[Example 1]
<Preparation of magnetic layer forming composition (coating liquid)>
in a plastic bottle,
Fe-Si-Al flat magnetic particles (MKT Sendust MFS-SUH): 10g
Resin 1 shown in Table 1: 1.8 g (6.0 g of Nipporan 5120 (solid content concentration 30% by mass) manufactured by Tosoh Corporation was used)
Resin 2 shown in Table 1: 0.2g
Total of resin 1 and resin 2 shown in Table 1: 2.0g
Polyfunctional isocyanate: 0.495g (0.66g of Takenate D101E (solid content concentration 75% by mass) manufactured by Mitsui Chemicals was used)
Cyclohexanone: 25g
was added and mixed for 12 hours using a shaking type stirrer to prepare a coating solution.

<Preparation of shield material>
(Film formation of magnetic layer)
The coating solution was applied to the release surface of a release-treated PET film (PET75-JOL manufactured by Nipper Co., Ltd.) using a blade coater with a coating gap of 300 μm, and dried for 30 minutes in a drying device with an internal atmosphere temperature of 80°C to form a film-like magnetic layer. was formed on the above-mentioned peel-treated PET film.

(Pressure treatment and heat treatment of magnetic layer)
The upper and lower press plates of a plate press machine (Mini Test Press manufactured by Toyo Seiki Co., Ltd.) were heated to 140°C (internal temperature of the press plate), and the magnetic layer from which the peel-treated PET film was peeled was placed between two Teflon sheets with a thickness of 1 mm. (registered trademark) sheets and held for 10 minutes under a pressure of 30 N/mm ² . After cooling the upper and lower press plates to 50° C. (internal temperature of the press plate) while maintaining the pressure, the magnetic layer was taken out from between the two Teflon (registered trademark) sheets.
Thereafter, in order to cause a crosslinking reaction between the resin contained in the magnetic layer and the polyfunctional isocyanate, the magnetic layer was kept in a drying device at an internal atmosphere temperature of 60° C. for 48 hours and heat-treated to obtain a magnetic layer.
In this way, a sheet-shaped electromagnetic shielding material composed only of the single magnetic layer was obtained.
Measurement samples for various evaluations described below were cut out from a part of the obtained magnetic layer.

<Evaluation of shielding ability (measurement of magnetic permeability before and after heating at 80°C)>
A measurement sample with a size of 28 mm x 10 mm was cut out from the above magnetic layer, and the magnetic permeability was measured using a magnetic permeability measuring device (per01 manufactured by Keycom Co., Ltd.), and the real part of the complex relative magnetic permeability (μ') at a frequency of 3 MHz was measured. The magnetic permeability was determined as follows (measurement temperature: 25°C). The magnetic permeability obtained in this manner is referred to as "magnetic permeability before heating at 80°C."
After measuring the magnetic permeability before thermal aging, the measurement sample was placed in a high temperature atmosphere of 80° C. for one day, and then the magnetic permeability was determined by the above method (measurement temperature: 25° C.). The magnetic permeability obtained in this way is referred to as "magnetic permeability after heating at 80°C."
Table 1 shows the evaluation results of "magnetic permeability before heat aging at 80°C" and "magnetic permeability after heat aging at 80°C" based on 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

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

<Acquisition of cross-sectional image of shield material>
Cross-section processing was performed to expose the cross-section of the shield material of Example 1 using the following method.
The shield material cut into a size of 3 mm x 3 mm was embedded in resin, and the cross section of the shield material was cut using an ion milling device (IM4000PLUS, manufactured by Hitachi High-Tech Corporation).
The cross section of the shielding material thus exposed was observed using a scanning electron microscope (SU8220, manufactured by Hitachi High-Technology) under conditions of an accelerating voltage of 2 kV and a magnification of 100 times, to obtain a backscattered electron image. The thickness of the shielding material (magnetic layer) was measured at five locations from the obtained image using the scale bar as a reference, and the arithmetic mean thereof was taken as the thickness of the shielding material (magnetic layer). The thickness of the shield material (magnetic layer) was 30 μm.

<Acquisition of cross-sectional image of magnetic layer>
In the cross section of the shielding material of Example 1 exposed by cross-sectional processing in the same manner as above, the magnetic layer portion was observed using a scanning electron microscope (SU8220 manufactured by Hitachi High-Tech Corporation) at an accelerating voltage of 2 kV and a magnification of 1000 times. A backscattered electron image was obtained.

<Measurement of aspect ratio of magnetic particles and degree of orientation of flat particles>
Using the reflected electron image obtained above, the aspect ratio of the magnetic particles was determined by the method described above, and flat particles were identified from the value of the aspect ratio. When it was determined as described above whether the magnetic layer contained flat particles as magnetic particles, it was determined that the magnetic layer contained flat particles. Furthermore, the degree of orientation of the magnetic particles identified as flat particles was determined by the method described above and was found to be 13°. In addition, the average value (arithmetic mean) of the aspect ratios of all particles identified as flat particles was determined as the aspect ratio of the flat particles contained in the magnetic layer. The aspect ratio determined was 0.071.

<Moldability>
A hemispherical three-dimensional molded product was produced by drawing the electromagnetic shielding material described above using a mold consisting of a male mold and a female mold (manufactured by Amada Corporation) at room temperature (25° C.) without heating. The presence or absence of breakage in the produced three-dimensional molded product was visually confirmed, and based on the confirmation results, the moldability was evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: Using a hemispherical mold with a depth of 2cm, it is possible to form a three-dimensional molded product with a depth of 2cm without breakage.
B: A three-dimensional molded product with a depth of 1 cm can be formed without breakage using a hemispherical mold with a depth of 1 cm.
Furthermore, when using a hemispherical mold with a depth of 2 cm,
Either the resulting three-dimensional molded product with a depth of 2 cm was broken, or the three-dimensional molded product with a depth of 2 cm could not be obtained.
C: A three-dimensional molded product with a depth of 1 cm obtained using a hemispherical mold with a depth of 1 cm was broken.

<Tensile test (elongation rate)>
A measuring sheet with a length of 50 mm and a width of 10 mm was cut out from the electromagnetic shielding material. A tensile test of this measurement sheet was carried out under the following measurement conditions using a Tensilon Universal Material Testing Machine (RTF-1310) manufactured by A&D as a tensile tester to determine the elongation rate. The elongation rate is calculated by setting the longest elongation of the test sheet pulled in the tensile test (i.e. the elongation displacement in the length direction at the time when at least one layer breaks in the measurement sheet) as L, and elongation rate [unit: %] = It is determined as 100×L/distance between chucks. The fact that at least one layer has fractured can be determined by the stress decrease in the stress-strain curve, visual inspection, and the like.
It is preferable that the value of the elongation rate determined in this way is 2.0% or more from the viewpoint of formability (for example, formability in cold forming), more preferably 5.0% or more, and 10.0% or more. It is more preferable that it is above. Further, the elongation rate may be, for example, 90.0% or less, 80.0% or less, 70.0% or less, or 60.0% or less, or may exceed the values exemplified herein.
(Measurement condition)
Distance between chucks: 25mm
Measurement environment: temperature 23℃, relative humidity 50%
Load cell: 500N (Newton)
Tensile speed: 1mm/min Tensile direction: Length direction

[Examples 2 to 9, Comparative Examples 1 to 4]
Electromagnetic shielding materials were produced and various evaluations were performed by the method described in Example 1, except that the items shown in Table 1 were changed as shown in Table 1.
For Examples 2 to 9 and Comparative Examples 1 to 4, the thickness of the shield material (magnetic layer) was determined by the method described above, and the thickness was the same as that determined for Example 1.

[Comparative example 5]
An attempt was made to produce an electromagnetic shielding material by the method described in Example 1, except that the items shown in Table 1 were changed as shown in Table 1. However, it was not possible to form an electromagnetic shielding material because the magnetic layer did not have sufficient self-supporting properties.

The above results are shown in Table 1. The high magnetic permeability of the magnetic layer can be said to indicate that the electromagnetic wave shielding material including the magnetic layer can exhibit excellent shielding ability against electromagnetic waves. For example, it can be said that an electromagnetic wave shielding material including a magnetic layer with high magnetic permeability after heating at 80° C. can exhibit excellent shielding ability against electromagnetic waves even after being placed under high temperature. As the evaluation results shown in the comprehensive evaluation column in Table 1, the lower evaluation result was adopted among the evaluation results of magnetic permeability after aging at 80° C. and the evaluation results of moldability. For example, when the two evaluation results are A and C, the evaluation result of the comprehensive evaluation is C. Regarding Comparative Example 5 in which the electromagnetic shielding material could not be produced, the evaluation result of the comprehensive evaluation was set as C.

From the results shown in Table 1, it can be confirmed that the electromagnetic shielding materials of Examples have excellent shielding ability after being placed under high temperature and excellent moldability.

The magnetic layer produced by the method described in Example 2 was used, and the metal layer was made of aluminum foil with a thickness of 50 μm (compliant with JIS H4160:2006 standard, alloy number 1N30 tempered (1) O, Al content 99.3% by mass) (above), the five layers of "aluminum foil (metal layer)/magnetic layer/aluminum foil (metal layer)/magnetic layer/aluminum foil (metal layer)" are interposed between two adjacent layers. A laminate was produced by overlapping each other without overlapping each other.
4. Heat the upper and lower press plates of a plate press machine (large hot press TA-200-1W manufactured by Yamamoto Iron Works Co., Ltd.) to 140°C (internal temperature of the press plate), and place the above laminate in the center of the press plate. The aluminum foil and the magnetic layer were bonded by thermocompression by applying a pressure of 66 N/mm ² for 10 minutes. After cooling the upper and lower press plates to 50° C. (internal temperature of the press plate) while maintaining the pressure, the laminate was taken out from the plate press.
In this way, an electromagnetic shielding material consisting of five layers of "aluminum foil (metal layer)/magnetic layer/aluminum foil (metal layer)/magnetic layer/aluminum foil (metal layer)" was obtained.
When the obtained electromagnetic shielding material was evaluated for moldability as described above, the same evaluation results as in Example 2 were obtained. In addition, since the electromagnetic shielding material thus produced includes the same magnetic layer as in Example 2, it has excellent shielding ability after being placed under high temperature like the electromagnetic shielding material of Example 2.

One embodiment of the present invention is useful in the technical fields of various electronic components and electronic devices.

Claims

having one or more magnetic layers containing magnetic particles and resin,
The content of the magnetic particles in the magnetic layer is more than 70 parts by mass and not more than 95 parts by mass, with the total mass of the magnetic layer being 100 parts by mass,
An electromagnetic shielding material, wherein the resin includes a urethane bond-containing resin and a diene resin, and the magnetic layer further includes a crosslinking agent.
The electromagnetic shielding material according to claim 1, wherein the content of the diene resin in the magnetic layer is 2 parts by mass or more and 15 parts by mass or less, based on a total content of the resin in the magnetic layer of 100 parts by mass.
The electromagnetic shielding material according to claim 1, wherein the urethane bond-containing resin has a glass transition temperature of -60°C or more and less than 0°C.
The electromagnetic shielding material according to claim 1, wherein the crosslinking agent is a polyfunctional isocyanate.
The electromagnetic shielding material according to claim 4, wherein the content of the polyfunctional isocyanate in the magnetic layer is 15 parts by mass or more, based on 100 parts by mass of the total content of the resin in the magnetic layer.
The content of the diene resin in the magnetic layer is 2 parts by mass or more and 15 parts by mass or less, with the total content of the resin in the magnetic layer being 100 parts by mass,
The glass transition temperature of the urethane bond-containing resin is -60°C or more and less than 0°C,
The crosslinking agent is a polyfunctional isocyanate, and the content of the polyfunctional isocyanate in the magnetic layer is 15 parts by mass or more, with the total content of the resin in the magnetic layer being 100 parts by mass. 1. The electromagnetic shielding material according to 1.
The electromagnetic shielding material according to claim 1, further comprising two or more metal layers, and one or more of the magnetic layers sandwiched between the two metal layers.
An electronic component comprising the electromagnetic shielding material according to any one of claims 1 to 7.
An electronic device comprising the electromagnetic shielding material according to any one of claims 1 to 7.