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

Abstract

Provided is an electromagnetic wave-shielding material which exhibits excellent shape retention. An electromagnetic wave-shielding material which contains a laminate which has a non-magnetic resin layer and a non-magnetic metal layer and / or ferromagnetic layer, wherein the value of the anisotropy during fracture (Rc) which is represented by formula (1) is less than or equal to 0 or is greater than or equal to 1.

Description

Electromagnetic wave shielding materials, covering materials or exterior materials, and electrical and electronic equipment

[0001] The present invention relates to an electromagnetic wave shielding material, a covering or exterior material, and an electric / electronic device.

[0002] In environmentally friendly vehicles equipped with secondary batteries, such as electric vehicles and hybrid vehicles, the direct current generated by the secondary batteries is converted into alternating current via an inverter, and the necessary power is then supplied to an AC motor to generate driving force. This system generates electromagnetic waves due to the switching operation of the inverter, etc.

[0003] Electromagnetic waves are emitted not only from automobiles but also from many other electrical and electronic devices, including communication devices, displays, and medical devices. Electromagnetic waves can cause precision equipment to malfunction, and there are also concerns about their effects on the human body.

[0004] It is known that a conductive layer such as copper typically exhibits good shielding properties against electromagnetic waves in the high frequency range (1 MHz or higher), whereas in the low frequency range (less than 1 MHz), a conductive layer such as copper alone has poor shielding properties against electromagnetic waves, and therefore an electromagnetic wave shielding material formed by alternately laminating magnetic layers with excellent magnetic permeability and conductive layers is known to exhibit good shielding properties against electromagnetic waves.

[0005] For example, Patent Document 1 proposes the following technology: "A noise suppression sheet used to suppress noise of 1 MHz or less, comprising a magnetic layer (A1) and a magnetic layer (A n and a noise suppression layer having n magnetic layers each having a ternary structure and at least (n-1) conductive layers, wherein the magnetic layers and the conductive layers are alternately stacked, and each of the magnetic layers has an X represented by the following formula (1): i is 1 or more, and X of each magnetic layer is i the sum of the above is 4 or more and 15 or less, and the proportional constant obtained when the shielding property of each of the conductive layers is linearly approximated in the range of 0.2 to 1 MHz in magnetic field shielding property measurement by the KEC method is 4 or more. i =√μ´ i ×√t i...Formula (1) where n is an integer of 2 or more, i is an integer of 1 or more and n or less, and μ' i is the magnetic layer (A i ) relative permeability at 1 MHz, t i is the magnetic layer (A i ) film thickness [mm].

[0006] Japanese Patent Application Laid-Open No. 2021-028940

[0007] Incidentally, electromagnetic wave shielding materials are sometimes drawn to fit the shapes of housings, electronic components, etc. as exterior materials. However, even if a shape having a desired height is formed by drawing, there is a problem in that the formed body after drawing cannot maintain its height, i.e., cannot retain its shape, due to the action of a force (springback) that causes the formed body to return to its pre-processing shape. In particular, depending on the material, the formed body may return to a height of about half of the height immediately after processing, which poses a problem in industrial production. Therefore, it would be extremely significant industrially if the shape retention of electromagnetic wave shielding materials could be improved. However, Patent Document 1 does not focus on the shape retention.

[0008] Therefore, an object of one embodiment of the present invention is to provide an electromagnetic wave shielding material that has excellent shape retention.

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems, and have found that an electromagnetic wave shielding material includes a laminate having a non-magnetic resin layer and a non-magnetic metal layer and / or a ferromagnetic layer, and that the anisotropy at break (Rc) value is 0 or less or 1 or more, thereby exhibiting excellent shape retention, and have created the invention exemplified below.

[0010] [1] An electromagnetic wave shielding material comprising a laminate having a nonmagnetic resin layer and a nonmagnetic metal layer and / or a ferromagnetic layer, wherein the value of anisotropy at break (Rc) represented by the following formula (1) is 0 or less or 1 or more.

[0011]

[0012] [2] The electromagnetic wave shielding material according to [1], wherein the laminate has the nonmagnetic metal layer, and the nonmagnetic resin layer is provided on both surfaces of the nonmagnetic metal layer.

[0013] [3] The electromagnetic wave shielding material according to [1] or [2], wherein the laminate has the ferromagnetic layer, and the nonmagnetic resin layer is provided on both surfaces of the ferromagnetic layer.

[0014] [4] The electromagnetic wave shielding material according to any one of [1] to [3], wherein the non-magnetic metal layer has a thickness of 10 to 200 μm and contains at least one metal having a breaking elongation of 2% or more in the RD direction.

[0015] [5] The electromagnetic wave shielding material according to any one of [1] to [4], wherein the nonmagnetic metal layer contains at least one selected from copper, a copper alloy, aluminum, and an aluminum alloy.

[0016] [6] The electromagnetic wave shielding material according to any one of [1] to [5], wherein the value of the anisotropy at break (Rc) of the non-magnetic resin layer, as shown in the following formula (2), is 1.0 or more and 10 or less, or −10 or more and 0 or less:

[0017]

[0018] [7] The electromagnetic wave shielding material according to any one of [1] to [6], wherein the non-magnetic resin layer contains at least one selected from PET and PC.

[0019] [8] The electromagnetic wave shielding material according to any one of [1] to [7], wherein the non-magnetic resin layer contains conductive particles and / or conductive fibers.

[0020] [9] A covering or exterior material for electrical and electronic devices, comprising the electromagnetic wave shielding material according to any one of [1] to [8].

[0021]

[10] An electric or electronic device provided with the covering material or exterior material of [9].

[0022] According to one embodiment of the present invention, it is possible to provide an electromagnetic wave shielding material that has excellent shape retention.

[0023] 1(A) to 1(C) are schematic diagrams for explaining the procedure of the shape retention test.

[0024] The present invention is not limited to the following embodiments, and various modifications and variations of the components can be made without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining the multiple components disclosed in the embodiments.

[0025] 1. Electromagnetic Wave Shielding Material One embodiment of the electromagnetic wave shielding material according to the present invention includes a laminate having a nonmagnetic resin layer, and a nonmagnetic metal layer and / or a ferromagnetic layer. Preferred embodiments of the laminate are described below.

[0026] <Laminate> (Anisotropy at break) From the viewpoint of ensuring excellent shape retention, the value of anisotropy at break in the laminate is 0 or less or 1 or more. When an electromagnetic wave shielding material is used as an exterior material, it is important to adjust the balance between thinning in the thickness direction and shrinkage in the width direction of the laminate from the viewpoint of ensuring excellent shape retention. Therefore, the following formula (1) is defined for the value of anisotropy at break. Anisotropy at break (Rc) indicates the degree of deformation in the thickness direction and the width direction when a plate-shaped sample is uniformly elongated. When the value of Rc is greater than 0 and less than 1, this indicates a state in which the width of the plate-shaped sample remains unchanged after processing but the thickness decreases. When the value of Rc is 1, this indicates a state in which the thickness and width change at the same rate before and after processing. When the value of Rc exceeds 1, this indicates a state in which the width changes after processing but the thickness does not change. It has been found that when metals are formed by drawing or other forming processes, materials prone to local elongation (0<Rc<1), such as copper and aluminum, undergo localized deformation, resulting in fracture and making the forming process itself difficult. Furthermore, when a composite sheet formed by mixing and dispersing a metal material and a resin into an integrally molded sheet is formed by drawing or other forming processes, materials with an Rc of 0<Rc<1 have poor shape retention. Based on these results, the inventors have discovered that when metals and resins are laminated together, if the Rc value of the laminate is 0 or less or 1 or greater, localized deformation is suppressed, facilitating forming and making it easier to maintain the shape after forming, leading to the present invention.

[0027]

[0028] To calculate the above formula (1), the width and thickness of the laminate before and after the tensile test are determined, and the ratio of the width strain to the thickness strain is calculated based on the following formulas (3) and (4). From this, it is possible to calculate the value of the anisotropy at break (Rc).

[0029]

[0030]

[0031] The method for measuring width strain and thickness strain in a tensile test is as follows. For the evaluation sample, the laminate was cut using a precision cutter to a width of 12.7 mm, and then cut to a length of 10 cm (100 mm) using a cutter, scissors, or the like. Next, using a bench-top precision universal testing machine (Autograph AGS-X, manufactured by Shimadzu Corporation), the evaluation sample was fixed so that each longitudinal end of the evaluation sample was clamped with a chuck (a test jig) to a length of 20 mm, and the initial chuck distance was 60 mm. Next, the evaluation sample was pulled in the longitudinal direction (longitudinal direction) at a tensile speed of 50 mm / min using the bench-top precision universal testing machine. The tensile test was terminated when the evaluation sample broke into two pieces. Based on the above formulas (3) and (4), the width strain and thickness strain of the evaluation sample were calculated from the width and thickness of the evaluation sample before and after the tensile test, and the Rc value was calculated. As an example of a method for measuring the thickness required to calculate the Rc value, it can be measured in accordance with Method A of JIS K 6250:2019 using a constant pressure thickness tester (THICKNESS METER B-1, manufactured by Toyo Seiki Seisakusho). Measurement can be performed with an indenter diameter of 5 mm and a pressure of 1.22 N applied to the indenter. As an example of a method for measuring the width, the broken portion can be fixed to cardboard with tape to prevent curling, and then measured using a vernier caliper. Regarding the width after fracture, the width is measured in the direction perpendicular to the longitudinal direction at the portion of the necking occurring near the fracture that is visually considered to be the smallest width.

[0032] The laminate can have a structure in which a nonmagnetic metal layer and / or a ferromagnetic layer are tightly laminated via a nonmagnetic resin layer. For example, if the laminate has a nonmagnetic metal layer, it is preferable to have a nonmagnetic resin layer on both surfaces of the nonmagnetic metal layer. A structure in which both surfaces of the nonmagnetic metal layer are tightly laminated with a nonmagnetic resin layer is desirable for improving the ductility of the nonmagnetic metal layer and enhancing the shape retention of the laminate. Metal foils such as copper and aluminum used as nonmagnetic metal layers are prone to local elongation, so sandwiching them between nonmagnetic resin layers, which are relatively resistant to local elongation, can mitigate local stress concentration. This ensures excellent shape retention. Furthermore, for example, if the laminate has a ferromagnetic layer, it is preferable to have a nonmagnetic resin layer on both surfaces of the ferromagnetic layer. The presence of the nonmagnetic resin layer can mitigate local stress concentration. This ensures excellent shape retention. In addition, when a nonmagnetic metal layer is provided on one surface of the ferromagnetic layer, it is preferable to provide a nonmagnetic resin layer on the other surface of the ferromagnetic layer opposite the nonmagnetic metal layer, and a nonmagnetic resin layer on the other surface of the nonmagnetic metal layer opposite the ferromagnetic layer. Indirectly sandwiching the nonmagnetic metal layer between nonmagnetic resin layers not only alleviates localized stress concentration, but also improves electromagnetic wave shielding properties and is expected to improve shape retention due to the presence of a layer with a high Young's modulus. It is also more preferable that the ferromagnetic layer be a composite sheet (an integrally molded product in which a magnetic metal material and a resin are mixed and dispersed). This ensures excellent shape retention.

[0033] (Layer Structure) Examples of the layer structure of the laminate include the following: (1) When the laminate is configured with two layers, examples include non-magnetic resin layer / ferromagnetic layer and non-magnetic resin layer / non-magnetic metal layer. (2) When the laminate is configured with three layers, examples include non-magnetic resin layer / ferromagnetic layer / non-magnetic resin layer, non-magnetic resin layer / non-magnetic metal layer / non-magnetic resin layer, non-magnetic resin layer / ferromagnetic layer / non-magnetic metal layer, non-magnetic resin layer / non-magnetic metal layer / ferromagnetic layer, ferromagnetic layer / non-magnetic resin layer / ferromagnetic layer, and ferromagnetic layer / non-magnetic resin layer / non-magnetic metal layer. (3) When the laminate has a four-layer structure, examples include non-magnetic resin layer / ferromagnetic layer / non-magnetic resin layer / ferromagnetic layer, non-magnetic resin layer / non-magnetic metal layer / non-magnetic resin layer / non-magnetic metal layer, non-magnetic resin layer / non-magnetic metal layer / ferromagnetic layer / non-magnetic resin layer, non-magnetic resin layer / ferromagnetic layer / non-magnetic resin layer, non-magnetic resin layer / ferromagnetic layer / non-magnetic resin layer / non-magnetic metal layer, and non-magnetic resin layer / non-magnetic metal layer / non-magnetic resin layer / ferromagnetic layer. (4) When the laminate has a five-layer structure, examples include non-magnetic resin layer / ferromagnetic layer / non-magnetic resin layer / ferromagnetic layer / non-magnetic resin layer, non-magnetic resin layer / non-magnetic metal layer / non-magnetic resin layer / non-magnetic metal layer / non-magnetic resin layer, non-magnetic resin layer / non-magnetic metal layer / ferromagnetic layer / non-magnetic metal layer / non-magnetic resin layer, and non-magnetic metal layer / non-magnetic resin layer / ferromagnetic layer / non-magnetic resin layer / non-magnetic metal layer. (5) When the laminate has six or more layers as its lamination structure, examples include non-magnetic resin layer / ferromagnetic layer / non-magnetic resin layer / ferromagnetic layer / non-magnetic resin layer / ferromagnetic layer, non-magnetic resin layer / non-magnetic metal layer / non-magnetic resin layer / non-magnetic metal layer / non-magnetic resin layer / non-magnetic metal layer, non-magnetic resin layer / non-magnetic metal layer / ferromagnetic layer / non-magnetic metal layer, non-magnetic resin layer / non-magnetic metal layer / ferromagnetic layer / non-magnetic resin layer, and non-magnetic resin layer / non-magnetic metal layer / non-magnetic resin layer / ferromagnetic layer / non-magnetic resin layer / non-magnetic metal layer / non-magnetic resin layer.

[0034] Here, in one embodiment, a single "non-magnetic resin layer" may include a layer formed by laminating multiple non-magnetic resin layers without an intervening ferromagnetic layer or non-magnetic metal layer. That is, in one embodiment, multiple non-magnetic resin layers laminated without an intervening ferromagnetic layer or non-magnetic metal layer are considered to be a single non-magnetic resin layer. Also, a non-magnetic resin layer on which an adhesive layer is laminated without an intervening ferromagnetic layer or non-magnetic metal layer is considered to be a single non-magnetic resin layer.

[0035] The shielding properties tend to improve as the number of laminations of non-magnetic resin layers, non-magnetic metal layers, and ferromagnetic layers increases, but increasing the number of laminations increases the amount of work, which leads to increased manufacturing costs, and the effect of improving the shielding properties tends to saturate once the number of laminations exceeds a certain level. Therefore, it is sufficient for the electromagnetic wave shielding material to have one or more non-magnetic resin layers, and one or more non-magnetic metal layers and / or ferromagnetic layers.

[0036] (Elongation at break) From the viewpoint of processability, the elongation at break in the RD direction of the laminate is preferably 10% or more, more preferably 30% or more. However, taking into consideration the appropriate elongation at break, the elongation at break in the RD direction is typically 300% or less, more typically 250% or less. Furthermore, from the viewpoint of processability, the elongation at break in the TD direction of the laminate is preferably 20% or more, more preferably 30% or more. However, taking into consideration the appropriate elongation at break, the elongation at break in the TD direction is typically 300% or less, more typically 250% or less. The RD direction refers to the roll conveyance direction of the nonmagnetic resin layer and / or nonmagnetic metal layer, and the TD direction refers to the direction rotated 90° from the RD direction. The method for measuring the elongation at break in each direction is as follows, in accordance with JIS K7127:1999. For the evaluation sample, the laminate was cut using a precision cutter to a width of 12.7 mm, and then cut to a length of 10 cm (100 mm) using a cutter, scissors, or the like. When measuring the elongation at break in the RD direction of the laminate, the evaluation sample was prepared so that the RD direction of the laminate was the longitudinal direction of the evaluation sample. When measuring the elongation at break in the TD direction of the laminate, the evaluation sample was prepared so that the TD direction of the laminate was the longitudinal direction of the evaluation sample. Using a test jig on a benchtop precision universal testing machine (Autograph AGS-X, manufactured by Shimadzu Corporation), the evaluation sample was fixed so that each end of the longitudinal direction of the evaluation sample was clamped with a gripping tool (chuck) of the test jig to a length of 20 mm, with an initial chuck distance of 60 mm. Next, the evaluation sample was pulled in the longitudinal direction (longitudinal direction) of the benchtop precision universal testing machine at a tensile speed of 50 mm / min. The tensile test is terminated when the evaluation sample breaks into two pieces. The value obtained by dividing the length displacement after deformation by the length before deformation, expressed as a percentage, is taken as the breaking elongation (%).

[0037] (Thickness) From the viewpoint of shape retention, the thickness of the laminate is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. However, from the viewpoint of the stress on the molded portion of the laminate formed during processing, the thickness of the laminate is preferably 800 μm or less, more preferably 700 μm or less, and even more preferably 600 μm or less. The method for measuring the thickness of the laminate is as follows. It can be measured in accordance with Method A of JIS K 6250:2019 using a constant pressure thickness tester (THICKNESS METER B-1, manufactured by Toyo Seiki Seisakusho). The diameter of the indenter is 5 mm, and the pressure on the indenter is 1.22 N.

[0038] (Lamination Method) The lamination method for the non-magnetic resin layer and the ferromagnetic layer or non-magnetic metal layer may involve using an adhesive between the non-magnetic resin layer and the ferromagnetic layer or between the non-magnetic resin layer and the non-magnetic metal layer, or may involve thermocompression bonding of the non-magnetic resin layer to the ferromagnetic layer or non-magnetic metal layer without using an adhesive. While a simple overlapping method without using an adhesive is also acceptable, considering the integrity of the electromagnetic wave shielding material, it is preferable to bond at least the edges (e.g., each side if the shielding material is rectangular) with tape, adhesive, or by thermocompression bonding. However, using an adhesive is preferable to avoid applying excessive heat to the ferromagnetic layer. The adhesive is not particularly limited, but examples include acrylic resins, epoxy resins, urethanes, polyesters, silicone resins, vinyl acetates, styrene-butadiene rubbers, nitrile rubbers, phenolic resins, and cyanoacrylates. Urethanes, polyesters, and vinyl acetates are preferred for ease of production and cost reasons.

[0039] <Non-magnetic Resin Layer> The non-magnetic resin layer contains a resin composition that is neither diamagnetic nor paramagnetic. A non-magnetic resin layer with a large impedance difference from the ferromagnetic layer or non-magnetic metal layer is preferable for achieving excellent electromagnetic wave shielding properties. To achieve a large impedance difference, the non-magnetic resin layer must have a low dielectric constant. Specifically, it is preferably 10 or less (value at 20°C; the same applies below), more preferably 5.0 or less, and even more preferably 3.5 or less. In principle, the dielectric constant cannot be less than 1.0. Generally available materials have a dielectric constant of at most 2.0. Lowering it further, closer to 1.0, only limits the improvement in shielding properties, while the material itself becomes specialized and expensive. Considering the balance between cost and shielding properties, a dielectric constant of 2.0 or more is preferable, and 2.2 or more is more preferable.

[0040] From the viewpoint of processability, synthetic resins are preferred as materials for the nonmagnetic resin layer. Film-like materials can also be used as materials for the nonmagnetic resin layer. Fiber reinforcement materials such as carbon fiber, glass fiber, and aramid fiber can also be mixed into the nonmagnetic resin layer. Synthetic resins include, from the viewpoints of availability and processability, polyesters such as PET (polyethylene terephthalate), PC (polycarbonate), PEN (polyethylene naphthalate), and PBT (polybutylene terephthalate), olefin resins such as polyethylene and polypropylene, polyamides, polyimides, liquid crystal polymers, polyacetals, fluororesins, polyurethanes, acrylic resins, epoxy resins, silicone resins, phenolic resins, melamine resins, ABS resins, polyvinyl alcohol, urea resins, polyvinyl chloride, polystyrene, and styrene-butadiene rubber. Among these, PET, PC, polyamides, and polyimides are preferred from the viewpoints of tensile strength and ductility. Other examples of synthetic resins that can be used include urethane rubber, chloroprene rubber, silicone rubber, fluororubber, styrene-based, olefin-based, vinyl chloride-based, urethane-based, and amide-based elastomers. Among these, polyimide, polybutylene terephthalate, polyamide, and polyurethane are preferred, as they are easily bonded to metal foil by thermocompression bonding. The nonmagnetic resin layers used in the laminate may all be made of the same resin material, or different resin materials may be used for each layer.

[0041] In a further embodiment, the non-magnetic resin layer may contain conductive particles and / or conductive fibers. Known metal species for the conductive particles and conductive fibers can be used as long as they have good conductivity, including copper, copper alloys, aluminum, aluminum alloys, and carbon. In this case, the mass ratio of the resin to the conductive particles or conductive fibers is, for example, 70:30 to 1:99.

[0042] The surface of the non-magnetic resin layer may be subjected to various surface treatments for the purpose of promoting adhesion with the non-magnetic metal layer or ferromagnetic layer, etc. For example, the adhesion between the resin film as the non-magnetic resin layer and the metal foil as the non-magnetic metal layer can be improved by applying a primer coat or corona treatment to the surface of the resin film as the non-magnetic resin layer that is to be attached to the metal foil as the non-magnetic metal layer.

[0043] (Anisotropy at Break) From the viewpoint of shape processability such as drawing, the value of the anisotropy at break of the non-magnetic resin layer is preferably 1.0 to 10 or -10 to 0, and more preferably 1.2 to 5 or -5 to -0. The value of the anisotropy at break is defined by the following formula (2). In formula (2), the width strain (ln(W / W0)) and thickness strain (ln(t / t0)) are measured in the same manner as the method for measuring the value of the anisotropy at break in the laminate described above.

[0044]

[0045] (Elongation at break) From the viewpoint of shape processability such as drawing, the elongation at break in the RD direction of the non-magnetic resin layer is preferably 10% or more, more preferably 20% or more, and even more preferably 80% or more. However, taking into consideration the appropriate elongation at break, the elongation at break in the RD direction is typically 500% or less, more typically 400% or less. Furthermore, from the viewpoint of shape processability such as drawing, the elongation at break in the TD direction of the non-magnetic resin layer is preferably 10% or more, more preferably 20% or more, and even more preferably 80% or more. However, taking into consideration the appropriate elongation at break, the elongation at break in the TD direction is typically 500% or less, more typically 400% or less. The method for measuring the elongation at break in each direction is the same as the method for measuring the elongation at break in each direction of the laminate described above.

[0046] (Thickness) The thickness of the non-magnetic resin layer is not particularly limited, but from the viewpoint of processability, the total thickness of the non-magnetic resin layer is preferably 40 μm or more, more preferably 50 μm or more, even more preferably 100 μm or more, and even more preferably 200 μm or more. However, from the viewpoint of cost reduction, the total thickness of the non-magnetic resin layer is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 300 μm or less.

[0047] Furthermore, in consideration of ease of handling, the thickness of each non-magnetic resin layer is preferably 5 μm or more, more preferably 20 μm or more, and even more preferably 25 μm or more. However, since an excessively large thickness per non-magnetic resin layer results in high costs (poor cutting processability), it is preferably 500 μm or less, and more preferably 300 μm or less. The method for measuring the thickness of the non-magnetic resin layer is the same as the method for measuring the thickness of the laminate described above.

[0048] (Thickness of Adhesive Layer) The adhesive layer is laminated on the surface of the non-magnetic resin layer and contains an adhesive. Considering formability, such as in drawing, adhesives with lower strength than resin films are often used. Therefore, if the adhesive layer is too thick, laminating a non-magnetic resin layer having the adhesive layer may hinder the improvement of the ductility of the ferromagnetic layer or non-magnetic metal layer. On the other hand, if the adhesive layer is too thin, it may be difficult to apply the adhesive to the entire interface between the ferromagnetic layer or non-magnetic metal layer and the non-magnetic resin layer, resulting in the risk of unbonded areas. Therefore, the thickness of the adhesive layer is preferably 1 μm or more and 20 μm or less, more preferably 1 μm or more and 10 μm or less, and even more preferably 3 μm or more and 9 μm or less. The adhesive layer may further contain conductive particles or conductive fibers within a range that does not impair the present invention. The method for measuring the thickness of the adhesive layer is the same as the method for measuring the thickness of the laminate described above.

[0049] <Ferromagnetic Layer> The ferromagnetic layer has electromagnetic wave absorption properties and a relative permeability of approximately 10 to 50,000 at a frequency of 1 MHz. The ferromagnetic layer contains a magnetic metal material with a high relative permeability. Examples of the ferromagnetic layer include a composite sheet and metal foil in which the magnetic metal material is mixed and dispersed with a resin and integrally molded. From the viewpoint of processability and light weight, a composite sheet is preferred. The general method for measuring relative permeability is as follows. The measurement sample is processed into a toroidal shape (outer diameter 6.93 to 6.96 mm, inner diameter 3.06 to 3.10 mm) using a punching die or the like, and the relative permeability can be measured using a vector network analyzer (ENA E5071C, manufactured by Keysight).

[0050] When the ferromagnetic layer is a composite sheet, the resin contained in the composite sheet can be natural resin or synthetic resin, with synthetic resin being preferred from the viewpoint of processability. Fiber reinforcement materials such as carbon fiber, glass fiber, and aramid fiber can also be mixed into these materials. Synthetic resins include, from the viewpoints of availability and processability, polyesters such as PET (polyethylene terephthalate), PC (polycarbonate), PEN (polyethylene naphthalate), and PBT (polybutylene terephthalate), olefin resins such as polyethylene and polypropylene, polyamide, PI (polyimide), LCP (liquid crystal polymer), polyacetal, fluororesin, polyurethane, acrylic resin, epoxy resin, silicone resin, phenolic resin, melamine resin, ABS resin, polyvinyl alcohol, urea resin, polyvinyl chloride, polystyrene, and styrene-butadiene rubber. Among these, PET, PC, PEN, polyamide, and PI are preferred from the viewpoints of processability and cost. Other examples of synthetic resins that can be used include urethane rubber, chloroprene rubber, silicone rubber, fluororubber, and elastomers based on styrene, olefin, vinyl chloride, urethane, and amide. Furthermore, the synthetic resin itself may function as an adhesive. While there are no particular limitations on the adhesive, examples include acrylic resins, epoxy resins, urethanes, polyesters, silicone resins, vinyl acetate, styrene-butadiene rubber, nitrile rubber, phenolic resins, and cyanoacrylates. Urethane, polyester, and vinyl acetate are preferred for ease of production and cost reasons. The composite sheet can be laminated to a non-magnetic resin layer or a non-magnetic metal layer in the form of a film or fiber. The composite sheet can be obtained by applying a mixed composition of an uncured magnetic metal material and a resin to a resin substrate having a release layer, curing the mixture, and then peeling it from the resin substrate. Alternatively, the composite sheet may be formed by applying a mixed composition of an uncured magnetic metal material and a resin to the surface of a non-magnetic resin layer, the surface of a non-magnetic metal layer, or a treatment film (described below), and then curing the mixture. Furthermore, for reasons of ease of production, it is preferable to use a composite sheet that can be attached to the surface of the non-magnetic resin layer, the surface of the non-magnetic metal layer, or the treated film described below.The mass ratio of resin to magnetic metal material in the composite sheet is, for example, 70:30 to 1:99. Furthermore, the composite sheet may further contain conductive particles or conductive fibers other than the magnetic metal material, as long as the present invention is not impaired. Examples of conductive particles and conductive fibers are the same as those in the non-magnetic resin layer described above.

[0051] When the ferromagnetic layer is in the form of a metal foil, it preferably contains at least one material selected from the group consisting of nickel, iron, permalloy (a Ni-Fe alloy), and sendust (an Fe-Si-Al alloy). These materials have relatively high relative permeability, making it possible to collect magnetic flux components contained in noise and reduce the spatial magnetic field.

[0052] (Elongation at break) From the viewpoint of processability such as drawing, the elongation at break in the RD direction of the ferromagnetic layer is preferably 5% or more, more preferably 10% or more. However, taking into consideration the appropriate elongation at break, the elongation at break in the RD direction is typically 100% or less, more typically 70% or less. Furthermore, from the viewpoint of processability such as drawing, the elongation at break in the TD direction of the ferromagnetic layer is preferably 5% or more, more preferably 10% or more. However, taking into consideration the appropriate elongation at break, the elongation at break in the TD direction is typically 100% or less, more typically 70% or less. The method for measuring the elongation at break in each direction is the same as the method for measuring the elongation at break in each direction of the laminate described above.

[0053] (Thickness) The thickness of the ferromagnetic layer is not particularly limited, but from the viewpoint of electromagnetic wave shielding properties, the total thickness of the ferromagnetic layers is preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, even more preferably 25 μm or more, and even more preferably 30 μm or more. However, from the viewpoint of cost reduction, the total thickness of the ferromagnetic layers is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less.

[0054] In one embodiment, from the viewpoint of stress on the molded portion of the laminate formed during processing, the thickness of each ferromagnetic layer is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, even more preferably 25 μm or more, even more preferably 30 μm or more, and even more preferably 35 μm or more. However, since an excessively large thickness per ferromagnetic layer increases costs, it is preferable that the thickness be 100 μm or less. The method for measuring the thickness of the ferromagnetic layer is the same as the method for measuring the thickness of the laminate described above.

[0055] In one embodiment, when multiple ferromagnetic layers are formed, all the ferromagnetic layers may be made of the same material, or different materials may be used for each layer, and all the ferromagnetic layers may have the same thickness, or different thicknesses may be used for each layer.

[0056] <Non-magnetic Metal Layer> The non-magnetic metal layer is made of a metal material that exhibits diamagnetic or paramagnetic properties. In one embodiment, there are no particular restrictions on the material used for the non-magnetic metal layer, but from the perspective of improving shielding properties against AC magnetic fields and AC electric fields, it is preferable to use a metal material with excellent conductivity. Specifically, a conductivity of 1.0×10 6 It is preferable that the conductive layer is made of a metal having a conductivity of 10.0×10 S / m (value at 20°C; the same applies below) or more. 6 S / m or more is more preferable, and 30.0×10 6 It is even more preferable that the value is 50.0×10 6 It is most preferable that the conductivity of such metals is about 39.6×10 S / m or more. 6 S / m of aluminum, conductivity is approximately 58.0 x 10 6 In other words, when considering both conductivity and cost, the non-magnetic metal layer preferably contains at least one material selected from copper, copper alloy, aluminum, and aluminum alloy. These are preferred from a practical standpoint.

[0057] (Elongation at break) From the viewpoint of formability, the elongation at break in the RD direction of the non-magnetic metal layer is preferably 2% or more, more preferably 5% or more. However, taking into consideration the appropriate elongation at break, the elongation at break in the RD direction is typically 80% or less, more typically 60% or less. Furthermore, from the viewpoint of formability, the elongation at break in the TD direction of the non-magnetic metal layer is preferably 2% or more, more preferably 5% or more. However, taking into consideration the appropriate elongation at break, the elongation at break in the TD direction is typically 80% or less, more typically 60% or less. The method for measuring the elongation at break in each direction is the same as the method for measuring the elongation at break in each direction of the laminate described above.

[0058] (Thickness) The thickness of the non-magnetic metal layer is not particularly limited, but from the viewpoint of shape retention, the total thickness of the non-magnetic metal layer is preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, even more preferably 25 μm or more, and even more preferably 30 μm or more. However, from the viewpoint of cost reduction, the total thickness of the non-magnetic metal layer is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 100 μm or less.

[0059] In one embodiment, from the viewpoint of shielding properties, the thickness of each non-magnetic metal layer is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. However, since an excessively large thickness per non-magnetic metal layer increases costs, the thickness is preferably 200 μm or less, more preferably 160 μm or less, and even more preferably 100 μm or less. The method for measuring the thickness of the non-magnetic metal layer is the same as the method for measuring the thickness of the laminate described above.

[0060] In one embodiment, when multiple non-magnetic metal layers are formed, all the non-magnetic metal layers may be made of the same material, or different materials may be used for each layer. Furthermore, all the non-magnetic metal layers may have the same thickness, or different thicknesses may be used for each layer. Furthermore, a treatment film, which will be described later, is considered to be part of the non-magnetic metal layer.

[0061] The shape of the nonmagnetic metal layer is not particularly limited, but examples include metal foil. When copper foil is used as the metal foil, a high purity is preferred because it improves shielding properties, with a purity of preferably 99.5% by mass or more, more preferably 99.8% by mass or more. Examples of copper foil that can be used include rolled copper foil, electrolytic copper foil, and metallized copper foil, but rolled copper foil is preferred because of its excellent flexural properties and formability. When alloying elements are added to copper foil to produce a copper alloy foil, the total content of these elements and unavoidable impurities should be less than 0.5% by mass. In particular, it is preferable for the copper foil to contain a total of 50 to 5,000 ppm by mass of at least one element selected from tin, manganese, chromium, zinc, zirconium, magnesium, nickel, silicon, and silver, and / or 10 to 50 ppm by mass of phosphorus, as this improves elongation compared to pure copper foil of the same thickness.

[0062] <Treatment Film> A treatment film of a copper-containing alloy may be further provided on one surface of the nonmagnetic metal layer, or the above treatment film may be further provided on both surfaces of the nonmagnetic metal layer. In this case, from the viewpoint of efficiently absorbing and attenuating electromagnetic waves in the ferromagnetic layer, it is preferable that the ferromagnetic layer and the nonmagnetic metal layer are disposed via a treatment film. The treatment film is formed, for example, on the surface of the nonmagnetic metal layer adjacent to the ferromagnetic layer, facing the ferromagnetic layer.

[0063] To enhance shielding properties, the treatment film is formed on at least one surface of the nonmagnetic metal layer. For example, the treatment film may further include one or more selected from copper-containing alloy electromagnetic wave absorption auxiliary films, heat-resistant films, rust-proof films, and weather-resistant films. Examples of heat-resistant films include plating films and vapor-deposited films containing cobalt or nickel. Examples of rust-proof films include inorganic plating films such as zinc or chromium, vapor-deposited films, and organic films such as benzotriazole. Examples of silane-coupling-treated weather-resistant films include organic coating films containing silane coupling agents. In other words, the treatment film may further include one or more metals selected from cobalt, nickel, zinc, molybdenum, tin, phosphorus, tungsten, chromium, and silicon in addition to copper. When the ferromagnetic layer is a composite sheet containing a resin, the treatment film interposed between the ferromagnetic layer and the nonmagnetic metal layer can also improve adhesion between the ferromagnetic layer and the nonmagnetic metal layer.

[0064] The electromagnetic wave absorbing auxiliary film can be produced by known methods, such as plating, metal vapor deposition, and sputtering. Among these, a method of forming an electromagnetic wave absorbing auxiliary film made of copper, an electromagnetic wave absorbing auxiliary film made of copper and nickel, or an electromagnetic wave absorbing auxiliary film made of copper, cobalt, and nickel by plating the surface of a nonmagnetic metal layer will be described below as an example. In the plating process for forming the electromagnetic wave absorbing auxiliary film, a particle film made of copper, a particle film made of copper and nickel, or a particle film made of copper, cobalt, and nickel is formed on at least one surface of the nonmagnetic metal layer.

[0065] (Plating Conditions (Roughening Plating) 1: Copper Plating) An example of copper plating conditions is as follows: Solution composition: copper 10 to 23 g / L, sulfuric acid 45 to 110 g / L Solution temperature: 20 to 55°C Current density: 10 to 60 A / dm 2 Coulomb amount: 5 to 30 As / dm 2

[0066] (Plating Conditions (Roughening Plating) 2: Copper and Nickel Alloy Plating) An example of the plating conditions for copper and nickel is as follows: Solution composition: copper 10 to 20 g / L, nickel 5 to 15 g / L pH: 2 to 3 Solution temperature: 30 to 50°C Current density: 10 to 65 A / dm 2 Coulomb amount: 10 to 50 As / dm 2

[0067] (Plating Conditions (Roughening Plating) 3: Copper, Cobalt, and Nickel Alloy Plating) An example of plating conditions for copper, cobalt, and nickel is as follows. Solution composition: copper 10 to 20 g / L, cobalt 5 to 15 g / L, nickel 5 to 15 g / L pH: 2 to 3 Solution temperature: 30 to 50°C Current density: 10 to 65 A / dm 2 Coulomb amount: 10 to 48 As / dm 2

[0068] In this case, under the above plating conditions 1 to 3, the roughening plating treatment can be carried out in multiple stages.

[0069] In the heat-resistant treatment, at least one of the following heat-resistant films 1 to 8 can be further formed on the aforementioned electromagnetic wave absorbing auxiliary film. The plating conditions and vapor deposition conditions are shown below.

[0070] (Plating conditions for heat-resistant film 1) (Co-Ni plating: cobalt-nickel alloy plating) Solution composition: nickel 5 to 20 g / L, cobalt 1 to 8 g / L pH: 2 to 3 Solution temperature: 40 to 60°C Current density: 10 to 30 A / dm 2 Coulomb amount: 2 to 20 As / dm 2

[0071] (Plating conditions for heat-resistant film 2) (Ni-Zn plating: nickel-zinc alloy plating) Solution composition: nickel 2 to 30 g / L, zinc 2 to 30 g / L pH: 3 to 4 Solution temperature: 30 to 50°C Current density: 1 to 10 A / dm 2 Coulomb amount: 0.5 to 2 As / dm 2

[0072] (Plating conditions for heat-resistant film 3) (Ni-Cu plating: nickel-copper alloy plating) Solution composition: nickel 2 to 30 g / L, copper 2 to 30 g / L pH: 3 to 4 Solution temperature: 30 to 50°C Current density: 1 to 2 A / dm 2 Coulomb amount: 1 to 2 As / dm 2

[0073] (Plating conditions for heat-resistant film 4) (Ni-Mo plating: nickel-molybdenum alloy plating) Solution composition: Ni sulfate hexahydrate: 45 to 55 g / dm 3 , Sodium molybdate dihydrate: 50 to 70 g / dm 3 , sodium citrate: 80 to 100 g / dm 3 pH: 1.5-4.5 Liquid temperature: 20-40℃ Current density: 1-4A / dm 2 Coulomb amount: 1 to 2 As / dm 2

[0074] (Plating conditions for heat-resistant film 5) (Ni-Sn plating: nickel-tin alloy plating) Solution composition: nickel 2 to 30 g / L, tin 2 to 30 g / L pH: 1.5 to 4.5 Solution temperature: 30 to 50°C Current density: 1 to 2 A / dm 2 Coulomb amount: 1 to 2 As / dm 2

[0075] (Plating conditions for heat-resistant film 6) (Ni-P plating: nickel-phosphorus alloy plating) Solution composition: nickel 30 to 70 g / L, phosphorus 0.2 to 1.2 g / L pH: 1.5 to 2.5 Solution temperature: 30 to 40°C Current density: 1 to 2 A / dm 2 Coulomb amount: 1 to 2 As / dm 2

[0076] (Plating conditions for heat-resistant film 7) (Ni-W plating: nickel-tungsten alloy plating) Solution composition: nickel 2 to 30 g / L, tungsten 0.01 to 5 g / L pH: 3 to 4 Solution temperature: 30 to 50°C Current density: 1 to 2 A / dm 2 Coulomb amount: 1 to 2 As / dm 2

[0077] (Vapor deposition conditions for heat-resistant film 8) (Ni—Cr vapor deposition: nickel-chromium alloy vapor deposition) A nickel-chromium alloy vapor deposition film is formed using a sputtering target having a composition of 65 to 85 mass% nickel and 15 to 35 mass% chromium. Target: 65 to 85 mass% nickel, 15 to 35 mass% chromium. Apparatus: Sputtering apparatus manufactured by ULVAC, Inc. Output: DC 50 W Argon pressure: 0.2 Pa

[0078] In the rust prevention treatment, the following rust prevention film and / or weather-resistant film can be further formed on the aforementioned electromagnetic wave absorbing auxiliary film or heat-resistant film. The respective conditions are shown below.

[0079] (Plating conditions for anti-rust film) Solution composition: potassium dichromate 1 to 10 g / L, zinc 0.2 to 0.5 g / L pH: 3 to 4 Solution temperature: 50 to 70°C Current density: 0 to 2 A / dm 2 (0 A / dm 2 is for immersion chromate treatment.) Coulomb amount: 0 to 2 As / dm 2 (0 As / dm 2 is for immersion chromate treatment.)

[0080] (Types of Weather-Resistant Films (Silane Coupling Films)) Examples include the application of an aqueous solution of diaminosilane or epoxysilane. Note that when a metal film such as a heat-resistant film or a plating film is formed by vapor deposition (dry plating) such as sputtering, or when a metal film such as a heat-resistant film or a plating film is formed by plating (wet plating) and the metal film such as a heat-resistant film or a plating film is normal plating (smooth plating, i.e., plating performed at a current density less than the limiting current density), the metal film or plating film does not affect the surface shape of the non-magnetic metal layer. The limiting current density varies depending on the metal concentration, pH, solution supply rate, electrode distance, and plating solution temperature. In this invention, however, the limiting current density is defined as the current density at the boundary between normal plating (a state in which the plated metal is deposited in a film) and roughened plating (burnt plating, a state in which the plated metal is deposited in a crystalline form (spherical, needle-like, frost-like, etc.), with unevenness). The limiting current density is the current density (visually determined) at the limit at which normal plating is achieved in a Hull cell test (just before burnt plating occurs). Specifically, the metal concentration, pH, and plating solution temperature are set to the plating production conditions, and a Hull cell test is performed. The state of metal layer formation (whether the plated metal is deposited in a layer or formed in a crystalline form) at the plating solution composition and plating solution temperature is then investigated. The current density at the boundary between normal plating and roughened plating is then determined based on a current density chart produced by Yamamoto Plating Tester Co., Ltd. The current density at the boundary is then defined as the limiting current density. This allows the critical current density to be determined for the plating solution composition and plating solution temperature. Generally, the shorter the electrode distance, the higher the critical current density tends to be. The Hull Cell test method is described, for example, in "Plating Practice Reader" by Kiyoshi Maruyama, published by Nikkan Kogyo Shimbun on June 30, 1983, pages 157 to 160. In order to perform plating below the critical current density, the current density during plating is set to 20 A / dm 2 It is preferable that the current is 10 A / dm or less. 2 More preferably, it is 8 A / dm or less. 2It is more preferable that the thickness of the anti-rust film and the weather-resistant film is extremely thin, and therefore does not affect the surface shape of the non-magnetic metal layer.

[0081] (Shielding Characteristics) According to one embodiment, the magnetic shielding characteristics (how much the signal is attenuated on the receiving side) can be 1 dB or more at 0.1 MHz, preferably 5 dB or more, more preferably 10 dB or more, even more preferably 15 dB or more, and even more preferably 18 dB or more. In the present invention, the magnetic shielding characteristics are measured by the KEC method. The KEC method refers to the "Electromagnetic Shielding Characteristics Measurement Method" established by the Kansai Electronics Industry Development Center.

[0082] (Uses) In one embodiment, the composition can be used for a variety of electromagnetic wave shielding applications, particularly as a covering or exterior material for electric and electronic devices (for example, inverters, communication devices, resonators, electron tubes and discharge lamps, electric heating devices, electric motors, generators, electronic components, printed circuits, medical devices, etc.), as a covering material for harnesses and communication cables connected to electric and electronic devices, and as an electromagnetic wave shielding sheet, an electromagnetic wave shielding panel, an electromagnetic wave shielding bag, an electromagnetic wave shielding box, an electromagnetic wave shielding room, etc.

[0083] The present invention will be specifically described based on examples, comparative examples, and reference examples. The following examples, comparative examples, and reference examples are merely specific examples intended to facilitate understanding of the technical content of the present invention, and the technical scope of the present invention is not limited by these specific examples. In Tables 1 and 2, "resin layer" corresponds to "non-magnetic resin layer," "metal layer" corresponds to "non-magnetic metal layer," and "magnetic layer" corresponds to "ferromagnetic layer," respectively.

[0084] [Material Consideration] (Reference Examples 1 to 8) First, in Reference Examples 1 to 8, the materials shown below were prepared, and the shape retention, elongation at break, shielding characteristics, and anisotropy at break values ​​of each material were measured. The results are shown in Table 1. Note that the RD direction of magnetic layer 1 and magnetic layer 2 refers to the longitudinal direction of the A4 sample, and the TD direction refers to the width direction. The measurement conditions and evaluation criteria are described below. The notation "-" in Table 1 indicates that no value was obtained even after measurement or that no measurement was performed. Note that the resin layers 1 to 3, adhesive layer 1, metal layers 1 and 2, and magnetic layers 1 and 2 in Tables 1 and 2 are as follows: Resin layer 1: PET film (thickness 98-103 μm, EMBLET SD100, manufactured by Unitika) Resin layer 2: Teflon (registered trademark) sheet (thickness 99 μm, Nitoflon, manufactured by Nitto Denko) Adhesive layer 1: Adhesive (thickness 18 μm, RU-80, manufactured by Rock Paint) Resin layer 3: Teflon (registered trademark) sheet (thickness 99 μm, Nitoflon, manufactured by Nitto Denko) having adhesive (thickness 18 μm, RU-80, manufactured by Rock Paint) on one surface Metal layer 1: Rolled copper foil (thickness 17.5 μm (nominal value), manufactured by JX Metals) Metal layer 2: Rolled copper foil (thickness 18 μm (nominal value), manufactured by JX Metals) Magnetic layer 1: Composite sheet (thickness 90-96 μm, GM010S, manufactured by Takeuchi Industries, relative permeability at a frequency of 1 MHz of approximately 24 (from catalog table)) Magnetic layer 2: Composite sheet (thickness 43-48 μm, P100NH, manufactured by Takeuchi Industries, relative permeability at a frequency of 1 MHz: approximately 130 (from the catalog table))

[0085] (Shape Retention) To evaluate the shape retention of each material in Reference Examples 1 and 5 to 8, compacts were produced at room temperature (approximately 22 to 26°C) using the following procedure. (1) Each material was clamped between the die and holder of the processing machine shown in FIG. 1(A). (2) As shown in FIG. 1(B), the punch was moved vertically downward along the die and holder and forced into the die hole. The clearance between the die and punch was set to 0.5 mm. The punch movement distance at which cracks did not occur on the surface of the compact when each material was molded was defined as the moldable stroke shown in Table 1. The stroke started at 3 mm and was increased by 1 mm each time, and the appearance of the compact was confirmed. If the compact molded at 3 mm broke, the moldable stroke was defined as 0. (3) As shown in FIG. 1(C), the punch was moved vertically upward and returned to its original position. This resulted in a compact with a bottom. (4) The molded height of the obtained molded body was measured using a confocal microscope (ONE-SHOT 3D VR-5000, manufactured by Keyence) at room temperature (approximately 22-26°C) the day after molding (after at least 12 hours had passed). The shortest distance in the vertical direction from the height position of the holder-side surface of the molded body sandwiched between the die and holder to the height position of the inner surface of the bottom was measured. Using the above procedure, the ratio (B / A) of the "molded height (B) of the molded body" to the obtained "moldable stroke (A)" was calculated. - Overall evaluation: When the ratio (B / A) was 75% or more, it was evaluated as "Good", when the ratio (B / A) was 50% or more but less than 75%, it was evaluated as "Good", and when the ratio (B / A) was less than 50%, it was evaluated as "Poor". The results are shown in Table 1.

[0086] (Breaking elongation) The breaking elongation in the RD direction and / or TD direction was measured for each of the materials of Reference Examples 1 and 4 to 8. The breaking elongation was measured at room temperature (approximately 22 to 26°C) using the method described above. The results are shown in Table 1.

[0087] (Shielding Properties) The shielding properties of each material in Reference Examples 1 to 8 were measured. First, the outer periphery of each material was fixed with tape to prevent misalignment during measurement. The magnetic field shielding properties of each material were evaluated at a frequency of 0.1 MHz by the KEC method at room temperature (approximately 22 to 26°C) using a magnetic field measuring jig of a KEC method shielding effectiveness measuring device (manufactured by Techno Science Corporation, JSE-KEC), a network analyzer (manufactured by Keysight Technologies, E5080), and an amplifier (manufactured by Anritsu Corporation, MH648A). The results are shown in Table 1. Overall evaluation: A magnetic field shielding property value of 10 dB or more at 0.1 MHz was evaluated as "Good," a magnetic field shielding property value of 1 dB or more but less than 10 dB was evaluated as "Average," and a magnetic field shielding property value of 1 dB or less but less than 1 dB was evaluated as "Poor." The results are shown in Table 1.

[0088] (Anisotropy at break) The anisotropy at break was measured for each of the materials of Reference Examples 1 to 8. The anisotropy at break was measured at room temperature (approximately 22 to 26°C) using the method described above. The results are shown in Table 1.

[0089]

[0090] (Discussion of Reference Examples) For resin layer 3 having adhesive layer 1 on resin layer 2, the Rc value was almost the same as that of resin layer 2. Since the Rc value of resin layer 1 and the Rc value of resin layer 2 were almost the same, it is believed that a similar trend would be confirmed even if the Rc value of a resin layer in which adhesive layer 1 was provided on resin layer 1 was measured. It is also inferred that even if an adhesive layer is provided on a non-magnetic resin layer, there is almost no effect on the Rc value. Furthermore, as in Reference Examples 7 and 8, when the Rc value was greater than 0 and less than 1, molding was possible with a moldable stroke of 3 mm, but the shape retention rate was less than 50%, confirming poor shape retention.

[0091] [Preparation of Electromagnetic Wave Shielding Material] (Examples 1 to 13, Comparative Examples 1 to 3) Next, in Comparative Example 1, laminate 1 was prepared as a commercially available electromagnetic wave shielding material, and the shape retention, breaking elongation, shielding properties, and anisotropy at break were measured in the same manner as in the Reference Example. The results are shown in Table 2. Laminate 1 was configured as follows. Laminate 1: Magnetic shielding sheet (thickness 120 μm, FM SHIELD (registered trademark), manufactured by Hitachi Metals) According to the catalog, laminate 1 is stacked in the following order: resin layer (PET film (thickness 25 μm)) / adhesive (hot melt adhesive (thickness 25 μm)) / magnetic layer 3 (thickness 18 μm, FINEMET (registered trademark), manufactured by Hitachi Metals, relative permeability at a frequency of 1 MHz: approximately 5000 (according to the table in the catalog)) / adhesive (hot melt adhesive (thickness 25 μm)) / resin layer (PET film (thickness 25 μm)). That is, the laminate 1 has a nonmagnetic resin layer / ferromagnetic layer / nonmagnetic resin layer configuration. Furthermore, in Examples 1 to 13 and Comparative Examples 2 and 3, electromagnetic wave shielding materials were prepared by appropriately combining the materials of Reference Examples 1 to 8 and the adhesive layer 2 described below. Then, in Examples 1 to 13 and Comparative Examples 2 and 3, shape retention, elongation at break, shielding characteristics, and anisotropy at break were measured in the same manner as in the Reference Example. The results are shown in Table 2. The areas of the bonded surfaces of the resin layer 1, metal layers 1 and 2, and magnetic layers 1 and 2 were the same, and they were laminated so as not to protrude from each other. In an example using a PET film for the resin layer 1 and a copper foil for the metal layer 1, an adhesive (two-component urethane resin adhesive, base: RU80, curing agent: H-5, manufactured by Rock Paint) was applied to the bonded surface of the PET film using a bar coater. In such cases, each resin layer was composed of a laminate of a PET film and an adhesive layer. Furthermore, resin layer 1 or metal layer 1 or 2 was attached to the outer surface of the adhesive layer already formed on magnetic layers 1 and 2. Adhesive layer 2 was as follows: Adhesive layer 2: Adhesive (thickness 4.5 μm, RU-80, manufactured by Rock Paint)

[0092]

[0093] (Discussion of Examples and Comparative Examples) In Examples 1 to 13, the shape retention was excellent and the shielding properties were also good. Therefore, in Examples 1 to 13, it can be said that an electromagnetic wave shielding material including a laminate having a nonmagnetic resin layer and a nonmagnetic metal layer and / or a ferromagnetic layer, in which the value of the anisotropy at break (Rc) shown in the above formula (1) is 0 or less or 1 or more, is useful. Furthermore, metals other than copper can also be used as the nonmagnetic metal layer. However, since aluminum has a lower tensile strength and is more easily deformed than copper, it is presumed that the effect of improving formability by laminating aluminum can also be obtained. In particular, by laminating one or more layers of each of a nonmagnetic resin layer, a nonmagnetic metal layer, and a ferromagnetic layer, the shielding properties at 0.1 MHz could be made 10 dB or more, resulting in a laminate that also excels as an electromagnetic wave shielding material. On the other hand, in Comparative Examples 1 to 3, a molded article could not be produced. Considering the results of Comparative Examples 1 to 3 and Reference Examples 1 to 8, it is presumed that if the value of the anisotropy at break (Rc) is not 0 or less or 1 or more, the electromagnetic wave shielding material will not have excellent shape retention.

Claims

1. An electromagnetic wave shielding material including a laminate having a nonmagnetic resin layer and a nonmagnetic metal layer and / or a ferromagnetic layer, An electromagnetic wave shielding material having a value of anisotropy at break (Rc) represented by the following formula (1) of 0 or less or 1 or more: [0010]

2. The laminate has the nonmagnetic metal layer, The electromagnetic wave shielding material according to claim 1 , further comprising the nonmagnetic resin layer on both surfaces of the nonmagnetic metal layer.

3. The stack has the ferromagnetic layer, The electromagnetic wave shielding material according to claim 1 , further comprising the non-magnetic resin layer on both surfaces of the ferromagnetic layer.

4. 4. The electromagnetic shielding material according to claim 1, wherein the nonmagnetic metal layer has a thickness of 10 to 200 μm and contains at least one metal having a breaking elongation of 2% or more in the RD direction.

5. 4. The electromagnetic shielding material according to claim 1, wherein the nonmagnetic metal layer comprises at least one selected from the group consisting of copper, a copper alloy, aluminum, and an aluminum alloy.

6. 4. The electromagnetic wave shielding material according to claim 1, wherein the non-magnetic resin layer has a value of anisotropy at break (Rc) represented by the following formula (2) of 1.0 or more and 10 or less, or -10 or more and 0 or less. [0025]

7. The electromagnetic wave shielding material according to any one of claims 1 to 3, wherein the nonmagnetic resin layer contains at least one selected from the group consisting of PET and PC.

8. The electromagnetic wave shielding material according to any one of claims 1 to 3, wherein the non-magnetic resin layer contains conductive particles and / or conductive fibers.

9. A covering or exterior material for electric / electronic devices, comprising the electromagnetic wave shielding material according to any one of claims 1 to 3.

10. An electric / electronic device comprising the covering or exterior material according to claim 9.

Images