Electromagnetic noise suppression sheet, method for manufacturing same, and cable using same

Abstract

This electromagnetic noise suppression sheet is provided with a substrate and a magnetic layer, the magnetic layer containing a magnetic material and a binder, and the binder containing an amorphous resin (A) having a glass transition temperature of-50 DEG C to 0 DEG C and an amorphous resin (B) having a glass transition temperature of 10 DEG C or more. The amorphous resin (A) is preferably an amorphous polyester (a) having a glass transition temperature of-50 DEG C to 0 DEG C, and the amorphous resin (B) is preferably an amorphous polyester (b) having a glass transition temperature of 10 DEG C or more.

Description

Technical Field

[0001] This application relates to an electromagnetic noise suppression sheet that absorbs electromagnetic waves in the kHz to GHz frequency band. Background Technology

[0002] With the development of wireless communication technologies, exemplified by mobile phones, various devices and sensors are connecting to networks wirelessly. Furthermore, in the medical field, from the perspective of infection prevention, devices are becoming wirelessly connected, and medical equipment is beginning to connect wirelessly. These communications require high speed and high capacity over short distances, and thus operate at high frequencies. With the increase in the use of such high-frequency devices, the risk of malfunctions in electronic devices and communications due to electromagnetic noise generated by the devices and interference from electromagnetic waves is increasing. Furthermore, in recent years, millimeter-wave radar, intended to prevent car collisions, has also begun to be incorporated. Malfunctions in these medical and automotive devices can affect human life, therefore, they must not malfunction. Therefore, the necessity of applying electromagnetic noise suppression chips—so-called EMC (Electromagnetic Compatibility) countermeasures—to circuit components and transmission paths that transmit and receive electromagnetic waves in the kHz to GHz frequency band is increasing.

[0003] In this context, Patent Document 1 proposes using a laminate containing a magnetic layer with magnetic powder and a binder resin, and a polymer compound film layer, as a magnetic sheet to suppress the transmission of electromagnetic waves. In this case, the binder resin used in the magnetic layer of the laminate in Patent Document 1 contains a crystalline polyester resin, thus achieving a non-adhesive laminate with excellent strength. On the other hand, if the magnetic layer contains a crystalline polyester resin, the crystallinity of the binder resin increases during the drying process in the manufacture of the magnetic layer, causing the magnetic layer to solidify. If the laminate is used as a magnetic sheet wound around a cable or connector, cracks may occur in the magnetic layer. Furthermore, if the magnetic layer contains a crystalline polyester resin, the adhesion between the magnetic layer and the polymer compound film layer will decrease, and the magnetic layer and the polymer compound film layer may peel off.

[0004] In addition, as a prior art document related to the use of the electromagnetic noise suppression sheet of this application, there is Patent Document 2. In Patent Document 2, a communication wire is disclosed in which a magnetic sheath layer formed by dispersing particulate magnetic material in a polymer material is formed into an extruded molded body.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Literature 1: Japanese Patent Application Laid-Open No. 2016-36965 (Japanese Patent No. 6428033)

[0008] Patent Literature 2: Japanese Patent Application Laid-Open No. 2022-108557 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] The present application solves the above problems and provides an electromagnetic noise suppression sheet which can be attached to a concave-convex surface, a curved surface of an electronic device in which influence of electromagnetic noise is desired to be prevented, and particularly which can be wound around a cable, a connector, and used, and which has electromagnetic wave absorption performance in a kHz-GHz band.

[0011] METHOD FOR SOLVING THE PROBLEMS

[0012] The electromagnetic noise suppression sheet of the present application includes a base material and a magnetic layer, the magnetic layer includes a magnetic material and a binder, and the binder includes an amorphous resin (A) having a glass transition temperature of -50°C to 0°C and an amorphous resin (B) having a glass transition temperature of 10°C or higher.

[0013] The manufacturing method of the electromagnetic noise suppression sheet of the present application is a method of manufacturing the above-described electromagnetic noise suppression sheet of the present application, and includes a step of mixing a magnetic material, an amorphous resin (A) having a glass transition temperature of -50°C to 0°C, and an amorphous resin (B) having a glass transition temperature of 10°C or higher together with a solvent to produce a magnetic layer-forming paint, and a step of applying the magnetic layer-forming paint to a base material and performing drying.

[0014] The cable of the present application includes the above-described electromagnetic noise suppression sheet of the present application.

[0015] EFFECTS OF THE INVENTION

[0016] According to the present application, it is possible to provide an electromagnetic noise suppression sheet which can be attached to a concave-convex surface, a curved surface of an electronic device, or wound around a cable, a connector, and used, and which has electromagnetic wave absorption performance in a kHz-GHz band. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic cross-sectional view showing an example of the electromagnetic noise suppression sheet of the embodiment.

[0018] Figure 2 is a schematic cross-sectional view showing another example of the electromagnetic noise suppression sheet of the embodiment.

[0019] Figure 3 is a schematic cross-sectional view showing an example of a conventional coaxial cable.

[0020] Figure 4is a schematic cross-sectional view showing an example of a coaxial cable of the embodiment. DETAILED DESCRIPTION

[0021] Electromagnetic noise suppression sheet

[0022] An embodiment of the electromagnetic noise suppression sheet of the present application will be described. The electromagnetic noise suppression sheet of the present embodiment is characterized by comprising a base material and a magnetic layer, the magnetic layer containing a magnetic material and a binder, the binder containing an amorphous resin (A) having a glass transition temperature of -50°C to 0°C and an amorphous resin (B) having a glass transition temperature of 10°C or higher.

[0023] In the electromagnetic noise suppression sheet of the present application, the magnetic layer contains the amorphous resin (A) having a glass transition temperature of -50°C to 0°C and the amorphous resin (B) having a glass transition temperature of 10°C or higher as the binder, and thus the flexibility (softness) and adhesion of the magnetic layer are excellent. Even if the electromagnetic noise suppression sheet of the present application is used by being wound around a cable or a connector, no cracks are generated in the magnetic layer, and the magnetic layer is not peeled off from the base material.

[0024] Further, as the amorphous resin (A), an amorphous polyester (a) having a glass transition temperature of -50°C to 0°C is particularly preferable, and as the amorphous resin (B), an amorphous polyester (b) having a glass transition temperature of 10°C or higher is particularly preferable. By using the amorphous polyester (a) having a glass transition temperature of -50°C to 0°C and the amorphous polyester (b) having a glass transition temperature of 10°C or higher as the binder of the magnetic layer, the flexibility and adhesion of the magnetic layer can be further improved.

[0025] Generally, when the glass transition temperature of an amorphous polyester is low, the adhesion and softness are improved, but the tackiness is increased, and on the other hand, when the glass transition temperature of an amorphous polyester is high, the tackiness is decreased, but the surface becomes hard and the softness is decreased. Therefore, in the binder of the present embodiment, it is preferable to use the amorphous polyester (a) having a glass transition temperature of -50°C to 0°C and the amorphous polyester (b) having a glass transition temperature of 10°C or higher in combination. Thereby, the adhesion and softness can be sufficiently ensured, and an electromagnetic noise suppression sheet in which the tackiness is suppressed can be realized.

[0026] Hereinafter, the electromagnetic noise suppression sheet of the present embodiment will be described based on the drawings. Figure 1 is a schematic cross-sectional view showing an example of the electromagnetic noise suppression sheet of the present embodiment. In Figure 1 , the electromagnetic noise suppression sheet 10 comprises a base material 11 and a magnetic layer 12 disposed on the base material 11. In Figure 1In the present embodiment, the electromagnetic noise suppression sheet 10 is a two-layer structure composed of the base material 11 and the magnetic layer 12, but can be further provided with an adhesive layer on the side of the magnetic layer 12 to be a three-layer structure.

[0027] In addition, Figure 2 is a schematic cross-sectional view showing another example of the electromagnetic noise suppression sheet of the present embodiment. In Figure 2 In the present embodiment, the electromagnetic noise suppression sheet 10' is provided with the base material 11, a metal layer 13 disposed on the base material 11, and a magnetic layer 12 disposed on the metal layer 13. In Figure 2 In the present embodiment, the electromagnetic noise suppression sheet 10' is a three-layer structure composed of the base material 11, the magnetic layer 12, and the metal layer 13, but can be further provided with an adhesive layer on the side of the magnetic layer 12 to be a four-layer structure.

[0028] The thickness of the entire electromagnetic noise suppression sheet of the present embodiment is preferably 10 to 85 μm, and more preferably 20 to 60 μm. This is because, if the thickness of the entire electromagnetic noise suppression sheet is too thin, the thickness of the magnetic layer also becomes thin, the electromagnetic wave absorbability decreases, and in addition, the strength of the entire sheet decreases. On the other hand, if the thickness of the entire electromagnetic noise suppression sheet is too thick, the softness decreases, and it is difficult to wind around the cable or the connector for use.

[0029] Next, each component of the electromagnetic noise suppression sheet of the present embodiment will be described.

[0030] <Base Material>

[0031] The base material used in the electromagnetic noise suppression sheet of the present embodiment becomes a base for forming the magnetic layer.

[0032] As the above-mentioned base material, a resin film is generally used as long as it has flexibility and can ensure adhesion to the magnetic layer. As the resin constituting the above-mentioned base material, for example, a base material composed of a polyolefin-based resin (polyethylene, polypropylene, etc.), a polyester-based resin (polyethylene terephthalate PET, polyethylene naphthalate PEN, polybutylene terephthalate PBT, polybutylene naphthalate PBN, etc.), a polyimide-based resin, a polyamide-based resin, an ethylene-vinyl acetate copolymer, an ionomer-based resin, an ethylene-(meth)acrylic acid copolymer, an ethylene-(meth)acrylic ester copolymer, an ethylene-butene copolymer, an ethylene-hexene copolymer, a polyurethane-based resin, a polyether ketone-based resin, a polyether-based resin, a polyether sulfone-based resin, a polystyrene-based resin (polystyrene, etc.), a polyvinyl chloride-based resin, a polyvinylidene chloride-based resin, a polyvinyl alcohol-based resin, a polyvinyl acetate-based resin, a vinyl chloride-vinyl acetate copolymer, a polycarbonate-based resin, a fluorine-based resin, a silicone-based resin, a cellulose-based resin, and a crosslinked body of these resins can be exemplified. Among them, polyethylene terephthalate (PET) is more preferable in terms of mechanical properties and price. One or two or more of these resin materials can be used. In addition, the above-mentioned resin material can have a functional group as needed. In addition, a functional monomer or a modifying monomer can be grafted to the resin material.

[0033] In order to improve adhesion to the adjacent magnetic layer, a publicly known surface treatment can be applied to the surface of the above-mentioned base material. As the above-mentioned surface treatment, specifically, for example, a corona discharge treatment, an ozone exposure treatment, a high-voltage electric shock exposure treatment, an ionized radiation treatment, and the like can be exemplified. In addition, a coating treatment based on a primer (a silicone treatment, etc.), a primer treatment, a matting treatment, a crosslinking treatment, and the like can be applied to the above-mentioned base material.

[0034] The above-mentioned base material can be a single layer or a laminate in which two or more layers are stacked. In addition, in the above-mentioned base material, a publicly known auxiliary agent such as a filler, a flame retardant, a deterioration preventive agent, an antistatic agent, a softening agent, a plasticizer, and the like can be added as needed.

[0035] The thickness of the above-mentioned base material is not particularly limited, and is preferably 5 to 20 μm, and more preferably 10 to 15 μm. If the thickness of the above-mentioned base material is within the above-mentioned range, the strength and flexibility of the electromagnetic noise suppression sheet of the present embodiment can be balanced.

[0036] The above-mentioned base material only needs to have flexibility and be able to ensure adhesion to the magnetic layer, and thus a metal layer such as a metal foil described later can be used instead of the above-mentioned resin film as the base material. That is, a metal layer can be used as the base material 11 of the electromagnetic noise suppression sheet 1. Figure 1

[0037] <Magnetic Layer>

[0038] ​The magnetic layer used in the electromagnetic noise suppression sheet of the present embodiment contains a magnetic material and a binder. The thickness of the magnetic layer is not particularly limited, and is generally set to a range of 5 to 70 μm, since the electromagnetic wave absorbing property is reduced when the thickness is too thin, and the softness is reduced when the thickness is too thick. Hereinafter, the constituent materials of the above magnetic layer will be described.

[0039] [Binder]

[0040] As the above binder, it is only necessary to contain an amorphous resin (A) having a glass transition temperature of -50°C to 0°C and an amorphous resin (B) having a glass transition temperature of 10°C or higher. The amorphous resin has high solubility in water or other solvents, and the dispersibility of the magnetic material (magnetic powder) is excellent, and thus by dispersing the magnetic powder in the resin dissolved in water or other solvents, and coating and drying on a substrate at an arbitrary thickness, it is possible to sheet the magnetic layer.

[0041] By using the amorphous resin (A) having a glass transition temperature of -50°C to 0°C, it is possible to further impart softness to the magnetic layer, and it is also possible to improve the adhesion of the magnetic layer to the substrate. However, when it is only the amorphous resin (A), the magnetic layer is likely to be sticky (tacky), and when the magnetic sheets are overlapped or wound in a roll shape, the magnetic layers can be likely to stick to each other. On the other hand, when it is only the amorphous resin (B) having a glass transition temperature of 10°C or higher, the surface of the magnetic layer is hard and difficult to attach, and the adhesion of the magnetic layer to the substrate can be reduced, and cracks can be likely to occur in the magnetic layer when wound for use. Therefore, as the binder of the present embodiment, the above amorphous resins (A) and (B) are used in combination.

[0042] The upper limit of the glass transition temperature of the amorphous resin (B) having a glass transition temperature of 10°C or higher is preferably 100°C, and more preferably 80°C. If the glass transition temperature is higher than this upper limit, even when used in combination with the amorphous resin (A) having a glass transition temperature of -50°C to 0°C, the surface of the magnetic layer is likely to be hard, the adhesion of the magnetic layer to the substrate is reduced, and when attached to a concave-convex surface, a curved surface, or wound and bent, the magnetic layer can be likely to easily crack.

[0043] As the above amorphous resin (A), an amorphous polyester, an amorphous polyurethane, an amorphous acrylic resin, or the like having a glass transition temperature of -50°C to 0°C can be used, and as the above amorphous resin (B), an amorphous polyester, an amorphous polyurethane, an amorphous acrylic resin, or the like having a glass transition temperature of 10°C or higher can be used. Among them, as the amorphous resin (A), an amorphous polyester (a) having a glass transition temperature of -50°C to 0°C is preferable, and as the amorphous resin (B), an amorphous polyester (b) having a glass transition temperature of 10°C or higher is preferable. Among the amorphous resins, the solubility and softness of the amorphous polyester are excellent, and it is suitable for manufacturing a sheet-shaped magnetic layer.

[0044] From the above viewpoint, the content ratio of the amorphous polyester (a) and the amorphous polyester (b) is preferably (a):(b) = 95:5 to 35:65, and more preferably (a):(b) = 90:10 to 50:50 in terms of mass ratio. The content ratio of the amorphous polyesters (a) and (b) can be determined to some extent by measuring the glass transition temperatures of the magnetic layer and according to the intensities of the peaks of the two glass transition temperatures detected. The glass transition temperature can be measured by a differential scanning calorimeter (DSC).

[0045] As the amorphous polyesters (a) and (b), for example, "VYLON" (registered trademark) manufactured by Toyobo Co., Ltd., "PLAS COAT" (registered trademark) manufactured by Kuraray Co., Ltd., "Nichigo-POLYESTER" (registered trademark) manufactured by Mitsubishi Chemical Corporation, "ALMATEX" (registered trademark) manufactured by Mitsui Chemicals, Inc., and the like can be given. They are excellent in solubility in water and organic solvents, and thus can be used by dissolving in water and organic solvents in an arbitrary ratio.

[0046] In addition, at least one of the amorphous polyester (a) and the amorphous polyester (b) preferably contains a crosslinked portion crosslinked by an amide bond. Thereby, the adhesion of the magnetic layer to the substrate can be further improved. Generally, the amorphous polyesters (a) and (b) have a carboxyl group at least at the molecular terminal, and in addition, since a carboxyl group can be arbitrarily imparted to the molecular chain thereof, by using a crosslinking agent having an oxazoline group, a carbodiimide group described later, a crosslinked portion crosslinked by an amide bond can be formed.

[0047] As the adhesive, in addition to the amorphous resin (A) and the amorphous resin (B), at least one of a crystalline resin and an amorphous resin having a glass transition temperature of greater than 0°C and less than 10°C can be contained to the extent that the effects of the application are not impaired. In this case, the total amount of the amorphous resin (A) and the amorphous resin (B) is preferably 90% by mass or more, and more preferably 95% by mass or more, with respect to the total amount of the adhesive.

[0048] [Magnetic material]

[0049] As the magnetic material, a soft magnetic material and a hard magnetic material can be used, but a soft magnetic material is preferably used. The soft magnetic material has a high initial magnetic permeability, and can exhibit electromagnetic wave absorbing performance even if a small amount is contained in the magnetic layer, and thus can exhibit an electromagnetic noise suppressing effect even if the magnetic layer is made into a thin film.

[0050] Examples of soft magnetic materials include iron, ferrosilicon, permalloy, Sendust alloy, Permendur alloy, soft magnetic ferrite, electromagnetic stainless steel, amorphous magnetic alloy, and nanocrystalline magnetic alloy. Among these, carbonyl iron represented by Fe(CO)5 is particularly preferred. This is because carbonyl iron can exhibit electromagnetic wave absorption properties (electromagnetic noise suppression effect) even in relatively high-frequency regions such as the GHz band.

[0051] Examples of hard magnetic materials include hard ferrite (ferrite magnet), AlNiCo magnet, Samarium Cobalt magnet, Neodymium magnet, and Samarium Iron Nitrogen magnet.

[0052] The aforementioned magnetic materials are typically supplied as spherical or flat powders, with an average particle size preferably of 0.1 to 100 μm, more preferably 1 to 20 μm. If the particle size of the magnetic material is too small, the particles tend to agglomerate secondary, making it difficult to obtain a uniform coating (magnetic layer). On the other hand, if the particle size is too large, the particles may protrude from the magnetic layer, thus the magnetic layer tends to peel off from the substrate when applied to uneven surfaces, curved surfaces, or when wound. Furthermore, if the particle size is large, it tends to settle during coating production, making it difficult to obtain a uniform coating. The aforementioned average particle size can be measured using a laser diffraction scattering particle size distribution measuring device.

[0053] The volume content of the soft magnetic material contained in the magnetic layer is preferably 30-80%, more preferably 40-70%. If the volume content is less than 30%, the electromagnetic wave absorption performance (electromagnetic noise suppression effect) of the magnetic layer tends to be insufficient. If it exceeds 80%, the proportion of binder in the magnetic layer decreases, and the adhesion of the magnetic layer to the substrate decreases, and cracks and powdering are prone to occur when the magnetic layer is bent.

[0054] <Metallic Layer>

[0055] like Figure 2 As shown, if a metal layer is disposed in the electromagnetic noise suppression sheet of this embodiment, the electromagnetic noise suppression sheet can be endowed with electric field shielding properties, which can suppress not only magnetic noise but also electrical noise. Figure 2 In this case, the metal layer is disposed between the substrate and the magnetic layer, but it can also be disposed on the outer surface of the magnetic layer.

[0056] The type of metal constituting the aforementioned metal layer is not particularly limited as long as it possesses flexibility and good adhesion to the magnetic layer; aluminum and copper are preferred. This is because aluminum and copper are inexpensive, easy to process into thin films, and have excellent flexibility.

[0057] The thickness of the aforementioned metal layer is not particularly limited, but if it is too thick, the flexibility will decrease. Therefore, it is usually set to a range of 0.1~30μm.

[0058] As the metal layer, a metal foil can be used alone, or a metal thin film can be formed on the above-mentioned substrate (resin film) by a vapor deposition method or a sputtering method.

[0059] In addition, as described above, the metal layer can be used as Figure 1 the substrate 11.

[0060] <Adhesive layer>

[0061] When the adhesive layer is provided on the electromagnetic noise suppression sheet of the present embodiment, the thickness of the adhesive layer is preferably 10 to 50 μm, and more preferably 15 to 35 μm. When the thickness is less than 10 μm, it can be difficult to obtain sufficient adhesion. In addition, when the thickness exceeds 50 μm, the adhesion effect of the adhesive layer is saturated, and the total thickness of the electromagnetic noise suppression sheet becomes large, so that the flexibility of the electromagnetic noise suppression sheet is reduced, the followability when attached to an electronic component is reduced, and it is difficult to wind around a wire or the like.

[0062] (Method for manufacturing electromagnetic noise suppression sheet)

[0063] An embodiment of the method for manufacturing the electromagnetic noise suppression sheet of the present application will be described. The method for manufacturing the electromagnetic noise suppression sheet of the present embodiment is a method for manufacturing the above-mentioned electromagnetic noise suppression sheet of the present application, and includes a step of mixing a magnetic material, an amorphous resin (A) having a glass transition temperature of -50°C to 0°C, and an amorphous resin (B) having a glass transition temperature of 10°C or higher together with a solvent to produce a magnetic layer-forming paint, and a step of applying the magnetic layer-forming paint to a substrate and drying it.

[0064] <Magnetic layer-forming paint>

[0065] The magnetic layer-forming paint can be produced by mixing a magnetic material, an amorphous resin (A) having a glass transition temperature of -50°C to 0°C, an amorphous resin (B) having a glass transition temperature of 10°C or higher, and a solvent. In general, the paint properties of amorphous resins are excellent, so that by using the above-mentioned magnetic layer-forming paint, a magnetic layer can be easily formed on a substrate in a usual coating step.

[0066] As the magnetic material, the same magnetic material as that constituting the magnetic layer of the above-mentioned electromagnetic noise suppression sheet of the present application can be used.

[0067] As the amorphous resin (A) having a glass transition temperature of -50°C to 0°C and the amorphous resin (B) having a glass transition temperature of 10°C or higher, the same material as that constituting the resin material of the magnetic layer of the above-mentioned electromagnetic noise suppression sheet can be used.

[0068] In addition, the resin of at least one of the amorphous resin (A) having a glass transition temperature of -50°C to 0°C and the amorphous resin (B) having a glass transition temperature of 10°C or higher preferably contains a carboxyl group. Thus, by using a crosslinking agent, a crosslinked portion can be formed in the amorphous resin (A) and (B).

[0069] As described above, the amorphous polyester has a carboxyl group at least at the molecular terminal, and in addition, a carboxyl group can be arbitrarily imparted to the molecular chain, and thus, as the amorphous resin (A), an amorphous polyester (a) having a glass transition temperature of -50°C to 0°C is particularly preferable, and as the amorphous resin (B), an amorphous polyester (b) having a glass transition temperature of 10°C or higher is particularly preferable. Furthermore, the amorphous polyester is more water-soluble, and the magnetic material is also excellent in wettability with respect to water-based solvents, and thus, the amorphous polyester is easily dispersed with the magnetic material in a water-based solvent.

[0070] As the crosslinking agent contained in the coating material for forming the magnetic layer, a resin having at least one selected from an oxazoline group and a carbodiimide group is preferable. The oxazoline group and the carbodiimide group react with a carboxyl group to form an amide bond, and thus, the amorphous polyester resins (a) and (b) can be crosslinked by the amide bond. Thus, the adhesion of the formed magnetic layer can be further improved, and the magnetic powder can be prevented from falling off during formation of the magnetic layer.

[0071] The crosslinking agent reacts with the carboxyl group of the amorphous polyester by heat during a drying step after the coating material for forming the magnetic layer is applied to the substrate, and forms a crosslinked portion based on an amide bond. In contrast, a crosslinked portion can also be formed by an epoxy bond, a urethane bond, or the like, but since the reaction speed for crosslinking formation is slow in the case of the epoxy bond, the urethane bond, or the like, the crosslinking reaction is not completed in some cases until the winding step after the drying step after the coating material is applied to the substrate, and the magnetic layers can be attached to each other in the winding step and the aging step thereafter.

[0072] As the resin having an oxazoline group, for example, "EPOCROS" (registered trademark) manufactured by Nippon Shokubai Co., Ltd. or the like can be given, and as the resin having a carbodiimide group, for example, "CARBODILITE" (registered trademark) manufactured by Nippon Shokubai Co., Ltd. or the like can be given.

[0073] As the solvent, water is preferably used. The magnetic material has excellent wettability with water, can be easily dispersed in water, can achieve homogenization of the coating film containing the magnetic material, and can improve the filling property of the magnetic material in the coating film. In addition, in addition to water, water-soluble solvents such as ethanol, methanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, and propylene glycol can be used. These water-soluble solvents can be used alone, or a plurality of kinds thereof can be used in mixture, or can be used in mixture with water, and a desired coating can be obtained.

[0074] The content of the solvent is not particularly limited, and can be 50.0% by mass or more and 99.5% by mass or less, relative to the total mass of the coating material for forming the magnetic layer.

[0075] In the coating material for forming the magnetic layer, a surface adjusting material, a defoaming agent, a thickening agent, or the like can be further added.

[0076] <Formation of magnetic layer>

[0077] As a method of applying the coating material for forming the magnetic layer to the substrate, a coating method such as bar coating, reverse coating, gravure coating, micro gravure (registered trademark) coating, die coating, dip coating, spin coating, slit coating, spray coating, or the like can be used.

[0078] The drying after the application can be performed under a condition in which the solvent component of the coating material for forming the magnetic layer is evaporated, and is preferably performed at 100 to 150°C for 3 to 30 minutes. If the solvent remains in the magnetic layer, there is a tendency that the strength is poor. As the drying method, for example, hot air drying, heat drying, vacuum drying, natural drying, or the like can be performed.

[0079] (Cable)

[0080] An embodiment of the cable of the present application will be described. The cable of the present embodiment is characterized by being provided with the electromagnetic noise suppression sheet of the above-described embodiment of the present application. The cable of the present embodiment includes a coaxial cable, a twisted pair cable, a multi-core cable, and the like. In particular, as a high frequency transmission, a coaxial cable is used, and is used for a video cable use.

[0081] Hereinafter, a coaxial cable, which is an example of the cable of the present embodiment, will be described. In the present coaxial cable, the above-described electromagnetic noise suppression sheet of the present application is used as a magnetic sheath layer of the coaxial cable. By using the electromagnetic noise suppression sheet of the present application as the magnetic sheath layer of the coaxial cable, the electromagnetic noise suppression sheet of the present application can function as an electromagnetic noise suppression layer of the coaxial cable. In addition, by using the electromagnetic noise suppression sheet of the present application as the magnetic sheath layer of the coaxial cable, it is possible to prevent cracks from occurring in the magnetic sheath layer, and it is possible to prevent the magnetic powder from falling off from the cut surface when the coaxial cable is cut.

[0082] Next, the coaxial cable of the present embodiment is described based on the drawings in comparison with the conventional coaxial cable.

[0083] Figure 3 is a schematic cross-sectional view showing an example of the conventional coaxial cable. In Figure 3 the conventional coaxial cable 20 has an inner conductor 21, an insulating layer 22, a metal foil 23, a metal braid 24, a magnetic sheath layer 25, and an outer covering layer 26. Details of each constituent member of the coaxial cable 20 are described in detail in Patent Literature 2 (Japanese Patent Application Publication No. 2022-108557).

[0084] The magnetic sheath layer 25 of the above-described conventional coaxial cable 20 is formed as an extrusion-molded body by extrusion-molding a magnetic sheath layer-forming material, which is formed by dispersing a magnetic powder in a base material composed of a high molecular material, to the outer surface of a wire-shaped conductor composed of the inner conductor 21, the insulating layer 22, the metal foil 23, and the metal braid 24. Therefore, there is a problem that the thickness of the magnetic sheath layer 25 becomes thick and the processing time also becomes long. Furthermore, when the coaxial cable is cut, the magnetic powder is easily detached from the cut surface.

[0085] In view of this, Figure 4 is a schematic cross-sectional view showing an example of the coaxial cable of the present embodiment. The coaxial cable 30 of the present embodiment has an inner conductor 31, an insulating layer 32, a metal foil 33, a metal braid 34, a magnetic sheath layer 35, and an outer covering layer 36. The magnetic sheath layer 35 uses the electromagnetic noise suppression sheet of the present application and is composed of a base material layer 35a and a magnetic layer 35b disposed on one face of the base material layer 35a.

[0086] In Figure 4 the magnetic layer 35b of the magnetic sheath layer 35 is disposed on the axis core side, but the base material layer 35a can be disposed on the axis core side.

[0087] The magnetic sheath layer 35 of the coaxial cable 30 of the present embodiment can be formed by winding the electromagnetic noise suppression sheet of the present application to the outer surface of a wire-shaped conductor composed of the inner conductor 31, the insulating layer 32, the metal foil 33, and the metal braid 34. Therefore, it is possible to make the thickness of the magnetic sheath layer thin, and in addition, it is possible to shorten the processing time. Furthermore, when the coaxial cable is cut, it is possible to prevent the magnetic powder from detaching from the cut surface.

[0088] In addition to the above-described coaxial cable, the electromagnetic noise suppression sheet of the present application can be used on the concave-convex surface and the corner portion of an electronic device that emits electromagnetic noise and an electronic device that wants to prevent electromagnetic noise. In addition, as a substitute for a ferrite core for an electronic device cable, the electromagnetic noise suppression sheet of the present application can also be used.

[0089] Example

[0090] Hereinafter, the present application will be described in detail using examples. However, the present application is not limited to the following examples. In the following description, "parts" means "mass parts" unless otherwise specified.

[0091] (Example 1)

[0092] <Preparation of coating material for magnetic layer formation>

[0093] A coating material A for magnetic layer formation was prepared by mixing and dispersing the following ingredients.

[0094] (1) Soft magnetic material (spherical carbonyl iron powder, manufactured by Tianyi Co., trade name "YW-3"): 53.43 parts

[0095] (2) Amorphous polyester (a) (water-soluble polyester resin solution, manufactured by Henshel Chemical Co., trade name "PLAS COAT Z-3310", Tg: -20°C, solid content concentration: 25.0 mass%, solvent: water): 15.77 parts

[0096] (3) Amorphous polyester (b) (water-soluble polyester resin solution, manufactured by Henshel Chemical Co., trade name "PLAS COAT Z-730", Tg: 43°C, solid content concentration: 25.0 mass%, solvent: water): 10.51 parts

[0097] (4) Solvent (n-propanol): 10.00 parts

[0098] (5) Purified water: 10.29 parts

[0099] In the above coating material A for magnetic layer formation, the contained ratio of the amorphous polyesters (a), (b) was (a):(b) = 60:40 in mass ratio, and the volume content of the soft magnetic material was 60% with respect to the total solid content of the above coating material A for magnetic layer formation.

[0100] <Formation of magnetic layer>

[0101] Next, a PET film (manufactured by Toyobo Co., trade name "Ester Film E 5100") having a thickness of 12 μm was used as a substrate, and the above coating material A for magnetic layer formation was applied to one main surface of the substrate using an applicator, and then dried at 120°C for 3 minutes. This was cut into a square of 150 mm, and pressed at 50°C, 210 kg / cm2using a press machine for 30 seconds, whereby an electromagnetic noise suppressing sheet of Example 1 having a magnetic layer formed on one main surface was produced. The thickness of the above magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppressing sheet was 50 μm. 2 was performed for 30 seconds, whereby an electromagnetic noise suppressing sheet of Example 1 having a magnetic layer formed on one main surface was produced. The thickness of the above magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppressing sheet was 50 μm.

[0102] (Example 2)

[0103] <Preparation of magnetic layer forming paint>

[0104] A magnetic layer forming paint B was prepared by mixing and dispersing the following ingredients.

[0105] (1) Soft magnetic material (flat carbonyl iron powder manufactured by Tenryi Co., trade name "YP"): 50.43 parts

[0106] (2) Amorphous polyester (a) (water-soluble polyester resin solution, manufactured by Kasei Kogyo Co., trade name "PLAS COAT Z-3310", Tg: -20°C, solid content concentration: 25.0 mass%, solvent: water): 30.63 parts

[0107] (3) Amorphous polyester (b) (water-soluble polyester resin solution, manufactured by Kasei Kogyo Co., trade name "PLAS COAT Z-730", Tg: 43°C, solid content concentration: 25.0 mass%, solvent: water): 7.66 parts

[0108] (4) Solvent (n-propanol): 10.00 parts

[0109] (5) Purified water: 1.28 parts

[0110] In the above magnetic layer forming paint B, the contained ratio of the amorphous polyesters (a), (b) was (a):(b) = 80:20 in terms of mass ratio, and the volume content of the soft magnetic material was 50% relative to the total solid content of the above magnetic layer forming paint B.

[0111] <Formation of magnetic layer>

[0112] Next, the magnetic layer forming paint B was used instead of the magnetic layer forming paint A of Example 1, and otherwise, an electromagnetic noise suppressing sheet of Example 2 in which a magnetic layer was formed was produced in the same manner as in Example 1. The thickness of the above magnetic layer was 28 μm, and the total thickness of the electromagnetic noise suppressing sheet was 40 μm.

[0113] (Example 3)

[0114] <Preparation of magnetic layer forming paint>

[0115] A magnetic layer forming paint C was prepared by mixing and dispersing the following ingredients.

[0116] (1) Soft magnetic material (spherical carbonyl iron powder manufactured by Tenryi Co., trade name "YW-5"): 53.01 parts

[0117] (2) Amorphous polyester (a) (water-soluble polyester resin solution, manufactured by Mitsui & Co., Inc., trade name "PLAS COAT Z-3310", Tg: -20°C, solid content concentration: 25.0 mass%, solvent: water): 19.56 parts

[0118] (3) Amorphous polyester (b) (water-soluble polyester resin solution, manufactured by Mitsui & Co., Inc., trade name "PLAS COAT Z-730", Tg: 43°C, solid content concentration: 25.0 mass%, solvent: water): 8.38 parts

[0119] (4) Polymer containing oxazoline group (manufactured by Nippon Shokubai Co., Ltd., trade name "EPOCROS WS 500", solid content concentration: 40.0 mass%, solvent: water): 2.00 parts

[0120] (5) Solvent (n-propanol): 10.00 parts

[0121] (6) Pure water: 7.04 parts

[0122] In the above magnetic layer-forming coating C, the contained ratio of the amorphous polyesters (a), (b) is (a):(b) = 70:30 in mass ratio, and the volume content of the soft magnetic material is 60% with respect to the total solid content of the above magnetic layer-forming coating C.

[0123] <Formation of magnetic layer>

[0124] Next, the magnetic layer-forming coating C was used instead of the magnetic layer-forming coating A of Example 1, and otherwise, an electromagnetic noise suppression sheet of Example 3 in which a magnetic layer was formed was produced in the same manner as in Example 1. The thickness of the above magnetic layer was 36 μm, and the total thickness of the electromagnetic noise suppression sheet was 48 μm.

[0125] (Example 4)

[0126] <Preparation of magnetic layer-forming coating>

[0127] A magnetic layer-forming coating D was prepared by mixing and dispersing the following components.

[0128] (1) Soft magnetic material (spherical carbonyl iron powder, manufactured by Tianyi Co., Ltd., trade name "YW-3"): 53.43 parts

[0129] (2) Amorphous polyester (a) (water-soluble polyester resin solution, manufactured by Mitsui & Co., Inc., trade name "PLAS COAT Z-3310", Tg: -20°C, solid content concentration: 25.0 mass%, solvent: water): 14.46 parts

[0130] (3) Amorphous polyester (b) (water-soluble polyester resin solution, manufactured by Mitsui & Co., Inc., trade name "PLAS COAT Z-730", Tg: 43°C, solid content concentration: 25.0 mass%, solvent: water): 11.83 parts

[0131] (4) Polymer containing carbodiimide group (manufactured by Nippon Shokubai Co., Ltd., trade name "CARBODILITE SV-02", solid content concentration: 40.0 mass%, solvent: water): 2.00 parts

[0132] (5) Solvent (n-propanol): 10.00 parts

[0133] (6) Purified water: 8.29 parts

[0134] In the above magnetic layer-forming coating D, the contained ratio of the amorphous polyesters (a), (b) is (a):(b) = 55:45 in mass ratio, and the volume content of the soft magnetic material is 60% relative to the total solid content of the above magnetic layer-forming coating D.

[0135] <Formation of magnetic layer>

[0136] Next, the magnetic layer-forming coating D described above was used instead of the magnetic layer-forming coating A of Example 1, and otherwise, an electromagnetic noise suppressing sheet of Example 4 formed with a magnetic layer was produced in the same manner as in Example 1. The thickness of the above magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppressing sheet was 50 μm.

[0137] (Example 5)

[0138] <Preparation of magnetic layer-forming coating>

[0139] A magnetic layer-forming coating E was prepared by mixing and dispersing the following components.

[0140] (1) Soft magnetic material (spherical Mn-Zn ferrite powder, manufactured by Todo Sangyo Co., Ltd., trade name "BSF-547"): 53.62 parts

[0141] (2) Amorphous polyester (a) (water-soluble polyester resin solution, manufactured by Mitsui & Co., Inc., trade name "PLAS COAT Z-3310", Tg: -20°C, solid content concentration: 25.0 mass%, solvent: water): 22.97 parts

[0142] (3) Amorphous polyester (b) (water-soluble polyester resin solution, manufactured by Mitsui & Co., Inc., trade name "PLAS COAT Z-730", Tg: 43°C, solid content concentration: 25.0 mass%, solvent: water): 2.55 parts

[0143] (4) Solvent (n-propanol): 10.00 parts

[0144] (5) Pure water: 10.86 parts

[0145] In the above-mentioned coating E for forming a magnetic layer, the content ratio of amorphous polyester (a) and (b) is (a):(b) = 90:10 by mass, and the volume content of soft magnetic material is 70% relative to the total solid content of the above-mentioned coating E for forming a magnetic layer.

[0146] <Formation of the Magnetic Layer>

[0147] Next, the magnetic layer forming coating E described above was used instead of the magnetic layer forming coating A of Example 1, and the electromagnetic noise suppression sheet of Example 5, which has a magnetic layer formed thereon, was fabricated in the same manner as in Example 1. The thickness of the magnetic layer is 40 μm, and the total thickness of the electromagnetic noise suppression sheet is 52 μm.

[0148] (Example 6)

[0149] The thickness of the magnetic layer was changed to 5 μm, and the total thickness of the electromagnetic noise suppression sheet was changed to 17 μm. Otherwise, the electromagnetic noise suppression sheet of Example 6 was made in the same manner as in Example 3.

[0150] (Example 7)

[0151] The thickness of the magnetic layer was changed to 70 μm, and the total thickness of the electromagnetic noise suppression sheet was changed to 82 μm. Otherwise, the electromagnetic noise suppression sheet of Example 7 was made in the same manner as in Example 3.

[0152] (Example 8)

[0153] <Preparation of Coatings for Forming Magnetic Layers>

[0154] The following components are mixed and dispersed to prepare a coating F for forming a magnetic layer.

[0155] (1) Soft magnetic material (spherical carbonyl iron powder manufactured by Tianyi Company, trade name "YW-5"): 53.01 parts

[0156] (2) Amorphous polyester (a) (water-soluble polyester resin solution, manufactured by Mutual Chemicals, trade name "PLAS COATZ-3310", Tg: -20℃, solid content concentration: 25.0% by mass, solvent: water): 27.39 parts

[0157] (3) Amorphous polyester (b) (water-soluble polyester resin solution, manufactured by Mutual Chemicals, trade name "PLAS COATZ-730", Tg: 43℃, solid content concentration: 25.0% by mass, solvent: water): 0.56 parts

[0158] (4) Oxazoline group-containing polymer (manufactured by Nippon Shokubai Co., Ltd., trade name "EPOCROS WS 500", solid content concentration: 40.0 mass%, solvent: water): 0.75 parts

[0159] (5) Solvent (n-propanol): 10.00 parts

[0160] (6) Pure water: 8.29 parts

[0161] In the above magnetic layer-forming coating F, the ratio of the amorphous polyester (a), (b) is (a):(b) = 98:2 in mass ratio, and the volume content of the soft magnetic material is 60% with respect to the total solid content of the magnetic layer-forming coating F.

[0162] <Formation of magnetic layer>

[0163] Next, the magnetic layer-forming coating F was used instead of the magnetic layer-forming coating A of Example 1, and otherwise, an electromagnetic noise suppression sheet of Example 8 in which a magnetic layer was formed was produced in the same manner as in Example 1. The thickness of the above magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppression sheet was 50 μm.

[0164] (Example 9)

[0165] <Preparation of magnetic layer-forming coating>

[0166] A magnetic layer-forming coating G was prepared by mixing and dispersing the following components.

[0167] (1) Soft magnetic material (spherical carbonyl iron powder manufactured by Tianyi Co., Ltd., trade name "YW-5"): 53.01 parts

[0168] (2) Amorphous polyester (a) (water-soluble polyester resin solution, manufactured by DKS Co., Ltd., trade name "PLAS COAT Z-3310", Tg: -20°C, solid content concentration: 25.0 mass%, solvent: water): 8.38 parts

[0169] (3) Amorphous polyester (b) (water-soluble polyester resin solution, manufactured by DKS Co., Ltd., trade name "PLAS COAT Z-730", Tg: 43°C, solid content concentration: 25.0 mass%, solvent: water): 19.56 parts

[0170] (4) Oxazoline group-containing polymer (manufactured by Nippon Shokubai Co., Ltd., trade name "EPOCROS WS 500", solid content concentration: 40.0 mass%, solvent: water): 0.75 parts

[0171] (5) Solvent (n-propanol): 10.00 parts

[0172] (6) Pure water: 8.30 parts

[0173] In the above-mentioned coating G for forming a magnetic layer, the containing ratio of the amorphous polyester (a), (b) is (a):(b) = 30:70 in terms of mass ratio, and the volume content of the soft magnetic material is 60% with respect to the total solid content of the above-mentioned coating G for forming a magnetic layer.

[0174] <Formation of a magnetic layer>

[0175] Next, the coating G for forming a magnetic layer described above was used instead of the coating A for forming a magnetic layer of Example 1, and otherwise, an electromagnetic noise suppressing sheet of Example 9 formed with a magnetic layer was produced in the same manner as in Example 1. The thickness of the above-mentioned magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppressing sheet was 50 μm.

[0176] (Example 10)

[0177] <Preparation of a coating for forming a magnetic layer>

[0178] A coating H for forming a magnetic layer was prepared by mixing and dispersing the following components.

[0179] (1) Soft magnetic material (spherical carbonyl iron powder manufactured by Tenryi Co., Ltd., trade name "YW-5"): 53.01 parts

[0180] (2) Amorphous polyurethane (a) (water-soluble polyurethane resin solution, manufactured by Toray Fine Chemical Co., Ltd., trade name "USC-2101", Tg: -33°C, solid content concentration: 35.0 mass%, solvent: water): 13.97 parts

[0181] (3) Amorphous polyester (b) (water-soluble polyester resin solution, manufactured by Mitsui & Co., Ltd., trade name "PLAS COAT Z-730", Tg: 43°C, solid content concentration: 25.0 mass%, solvent: water): 8.38 parts

[0182] (4) Polymer containing oxazoline group (manufactured by Nippon Shokubai Co., Ltd., trade name "EPOCROS WS 500", solid content concentration: 40.0 mass%, solvent: water): 0.75 parts

[0183] (5) Solvent (n-propanol): 10.00 parts

[0184] (6) Purified water: 13.89 parts

[0185] In the above-mentioned coating H for forming a magnetic layer, the containing ratio of the amorphous resins (a), (b) is (a):(b) = 70:30 in terms of mass ratio, and the volume content of the soft magnetic material is 60% with respect to the total solid content of the above-mentioned coating H for forming a magnetic layer.

[0186] <Formation of a magnetic layer>

[0187] Next, the magnetic layer forming coating H described above was used instead of the magnetic layer forming coating A of Example 1, and otherwise, an electromagnetic noise suppressing sheet of Example 10 in which a magnetic layer was formed was produced in the same manner as in Example 1. The thickness of the magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppressing sheet was 50 μm.

[0188] (Example 11)

[0189] Preparation of the magnetic layer forming coating

[0190] A magnetic layer forming coating I was prepared by mixing and dispersing the following components.

[0191] (1) Soft magnetic material (spherical carbonyl iron powder manufactured by Tenshoku Co., Ltd., trade name "YW-5"): 53.01 parts

[0192] (2) Amorphous acrylic resin (a) (water-soluble acrylic resin solution, manufactured by Dic Corporation, trade name "ABH-6201", Tg: -6°C, solid content concentration: 43.0 mass%, solvent: water): 13.00 parts

[0193] (3) Amorphous polyester (b) (water-soluble polyester resin solution, manufactured by Mitsui & Co., trade name "PLAS COAT Z-730", Tg: 43°C, solid content concentration: 25.0 mass%, solvent: water): 5.59 parts

[0194] (4) Polymer containing oxazoline group (manufactured by Nippon Shokubai Co., Ltd., trade name "EPOCROS WS 500", solid content concentration: 40.0 mass%, solvent: water): 0.75 parts

[0195] (5) Solvent (n-propanol): 10.00 parts

[0196] (6) Purified water: 17.65 parts

[0197] In the magnetic layer forming coating I described above, the contained ratio of the amorphous resins (a), (b) was (a):(b) = 80:20 in terms of mass ratio, and the volume content of the soft magnetic material was 60% with respect to the total solid content of the magnetic layer forming coating I described above.

[0198] Formation of the magnetic layer

[0199] Next, the magnetic layer forming coating I described above was used instead of the magnetic layer forming coating A of Example 1, and otherwise, an electromagnetic noise suppressing sheet of Example 11 in which a magnetic layer was formed was produced in the same manner as in Example 1. The thickness of the magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppressing sheet was 50 μm.

[0200] (Example 12)

[0201] <Preparation of magnetic layer forming coating material>

[0202] A magnetic layer forming coating material J was prepared by mixing and dispersing the following ingredients.

[0203] (1) Soft magnetic material (spherical carbonyl iron powder, manufactured by Tianyi Company, trade name "YW-5"): 53.01 parts

[0204] (2) Amorphous polyester-polyurethane (a) (polyester-polyurethane resin solution, manufactured by Toyobo MC Corporation, trade name "VYLON UR-6100", Tg: -30°C, solid content concentration: 45.0 mass%, solvent: cyclohexanone / aromatic solvent / isophorone = 40 mass% / 40 mass% / 20 mass%): 7.76 parts

[0205] (3) Amorphous polyester-polyurethane (b) (polyester-polyurethane resin solution, manufactured by Toyobo MC Corporation, trade name "VYLON UR-3600", Tg: 40°C, solid content concentration: 40.0 mass%, solvent: methyl ethyl ketone / toluene = 63 mass% / 37 mass%): 8.73 parts

[0206] (4) Isocyanate-based curing agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "CORONATE HX"): 0.2 parts

[0207] (5) Solvent (methyl ethyl ketone): 15.00 parts

[0208] (6) Solvent (toluene): 15.30 parts

[0209] In the above magnetic layer forming coating material J, the contained ratio of the amorphous polyester-polyurethane (a), (b) was (a):(b) = 50:50 in terms of mass ratio, and the volume content of the soft magnetic material was 60% with respect to the total solid content of the above magnetic layer forming coating material J.

[0210] <Formation of magnetic layer>

[0211] Next, using the above magnetic layer forming coating material J instead of the magnetic layer forming coating material A of Example 1, an electromagnetic noise suppression sheet of Example 12 in which a magnetic layer was formed was produced in the same manner as in Example 1. The thickness of the above magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppression sheet was 50 μm.

[0212] (Comparative Example 1)

[0213] <Preparation of magnetic layer forming coating material>

[0214] A magnetic layer forming coating material K was prepared by mixing and dispersing the following ingredients.

[0215] (1) Soft magnetic material (spherical carbonyl iron powder manufactured by Tenryi Co., Ltd., trade name "YW-3"): 53.43 parts

[0216] (2) Amorphous polyester (b) (water-soluble polyester resin solution, manufactured by Mitsui & Co., Ltd., trade name "PLAS COAT Z-730", Tg: 43°C, solid content concentration: 25.0 mass%, solvent: water): 26.29 parts

[0217] (3) Solvent (n-propanol): 10.00 parts

[0218] (4) Pure water: 10.28 parts

[0219] In the above magnetic layer-forming coating K, only the amorphous polyester (b) was used as the amorphous resin, and the volume content of the soft magnetic material was 60% with respect to the total solid content of the above magnetic layer-forming coating K.

[0220] <Formation of magnetic layer>

[0221] Next, the magnetic layer-forming coating K was used instead of the magnetic layer-forming coating A of Example 1, and otherwise, a comparative example 1 electromagnetic noise suppression sheet having a magnetic layer was produced in the same manner as in Example 1. The thickness of the above magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppression sheet was 50 μm.

[0222] (Comparative Example 2)

[0223] <Preparation of magnetic layer-forming coating>

[0224] A magnetic layer-forming coating L was prepared by mixing and dispersing the following components.

[0225] (1) Soft magnetic material (spherical carbonyl iron powder manufactured by Tenryi Co., Ltd., trade name "YW-3"): 53.43 parts

[0226] (2) Amorphous polyester (a) (water-soluble polyester resin solution, manufactured by Mitsui & Co., Ltd., trade name "PLAS COAT Z-3310", Tg: -20°C, solid content concentration: 25.0 mass%, solvent: water): 26.29 parts

[0227] (3) Solvent (n-propanol): 10.00 parts

[0228] (4) Pure water: 10.28 parts

[0229] In the above magnetic layer-forming coating L, only the amorphous polyester (a) was used as the amorphous resin, and the volume content of the soft magnetic material was 60% with respect to the total solid content of the above magnetic layer-forming coating L.

[0230] <Formation of magnetic layer>

[0231] Next, Comparative Example 2 was produced in the same manner as in Example 1, except that the magnetic layer forming coating L described above was used instead of the magnetic layer forming coating A of Example 1. The thickness of the magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppression sheet was 50 μm.

[0232] (Comparative Example 3)

[0233] <Preparation of magnetic layer forming coating>

[0234] A magnetic layer forming coating M was prepared by mixing and dispersing the following components.

[0235] (1) Soft magnetic material (spherical carbonyl iron powder manufactured by Tianyi Company, trade name "YW-5"): 53.01 parts

[0236] (2) Amorphous polyester-polyurethane (a) (polyester-polyurethane resin solution, manufactured by Toyobo MC Corporation, trade name "VYLON UR-6100", Tg: -30°C, solid content concentration: 45.0 mass%, solvent: cyclohexanone / aromatic solvent / isophorone = 40 mass% / 40 mass% / 20 mass%): 7.76 parts

[0237] (3) Amorphous polyester (b) (polyester resin solution, manufactured by Toyobo MC Corporation, trade name "VYLON 500", Tg: 4°C, solid content concentration: 30.0 mass%, solvent: methyl ethyl ketone): 11.65 parts

[0238] (4) Isocyanate-based curing agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "CORONATE HX"): 0.2 parts

[0239] (5) Solvent (methyl ethyl ketone): 15.00 parts

[0240] (6) Solvent (toluene): 12.38 parts

[0241] In the magnetic layer forming coating M described above, the contained ratio of the amorphous resins (a), (b) was (a):(b) = 50:50 in terms of mass ratio, and the volume content of the soft magnetic material was 60% with respect to the total solid content of the magnetic layer forming coating M.

[0242] <Formation of magnetic layer>

[0243] Next, Comparative Example 3 was produced in the same manner as in Example 1, except that the magnetic layer forming coating M described above was used instead of the magnetic layer forming coating A of Example 1. The thickness of the magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppression sheet was 50 μm.

[0244] (Comparative Example 4)

[0245] <Preparation of coating material for magnetic layer formation>

[0246] A coating material for magnetic layer formation N was prepared by mixing and dispersing the following ingredients.

[0247] (1) Soft magnetic material (spherical carbonyl iron powder, manufactured by Tianyi Company, trade name "YW-5"): 53.01 parts

[0248] (2) Amorphous polyester (a) (polyester resin solution, manufactured by Toyobo MC Corporation, trade name "VYLON 500", Tg: 4°C, solid content concentration: 30.0 mass%, solvent: methyl ethyl ketone): 7.76 parts

[0249] (3) Amorphous polyester-polyurethane (b) (polyester-polyurethane resin solution, manufactured by Toyobo MC Corporation, trade name "VYLON UR-3600", Tg: 40°C, solid content concentration: 40.0 mass%, solvent: methyl ethyl ketone / toluene = 63 mass% / 37 mass%): 8.73 parts

[0250] (4) Isocyanate-based curing agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "CORONATE HX"): 0.2 parts

[0251] (5) Solvent (methyl ethyl ketone): 15.00 parts

[0252] (6) Solvent (toluene): 11.41 parts

[0253] In the above coating material for magnetic layer formation N, the contained ratio of the amorphous resins (a), (b) was (a):(b) = 50:50 in terms of mass ratio, and the volume content of the soft magnetic material was 60% with respect to the total solid content of the above coating material for magnetic layer formation N.

[0254] <Formation of magnetic layer>

[0255] Next, using the above coating material for magnetic layer formation N instead of the coating material for magnetic layer formation A of Example 1, a comparative electromagnetic noise suppression sheet of Comparative Example 4 in which a magnetic layer was formed was produced in the same manner as in Example 1. The thickness of the above magnetic layer was 38 μm, and the total thickness of the electromagnetic noise suppression sheet was 50 μm.

[0256] The electromagnetic noise suppression sheets of Examples 1 to 12 and Comparative Examples 1 to 4 above were evaluated as follows.

[0257] <Adhesion>

[0258] First, 11 slits reaching the base material were formed at 1 mm intervals in the magnetic layer of the prepared electromagnetic noise suppression sheet using a cutter, and 100 checkers were prepared. Next, the checkers were strongly pressed with a transparent tape, the end of the tape was peeled off at an angle of 45°, and the state of the checkers was observed, and the adhesion of the magnetic layer of the electromagnetic noise suppression sheet was evaluated as follows.

[0259] Evaluation A: None of the checkers were peeled off

[0260] Evaluation B: The peeled-off portion of the checkers was less than 5%

[0261] Evaluation C: The peeled-off portion of the checkers was 5% or more

[0262] <Flexibility>

[0263] The prepared electromagnetic noise suppression sheet was cut into a 10 mm x 100 mm strip, and the base material surface of the strip was wound around the outer periphery of a stainless steel rod for approximately 360°, and held for 1 minute. Then, the magnetic layer of the wound strip was observed under a microscope, and the flexibility of the magnetic layer of the electromagnetic noise suppression sheet was evaluated as follows.

[0264] Evaluation A: No peeling or cracking of the magnetic layer occurred when wound around a 1 mm diameter stainless steel rod

[0265] Evaluation B: No peeling or cracking of the magnetic layer occurred when wound around a 2 mm diameter stainless steel rod

[0266] Evaluation C: Peeling or cracking of the magnetic layer occurred when wound around a 2 mm diameter stainless steel rod

[0267] <Adhesion>

[0268] Two pieces of the prepared electromagnetic noise suppression sheet were cut into 10 cm squares, and overlapped with the magnetic layer of one piece in contact with the base material of the other piece, and a 1 cm diameter weight was pressed on the overlapped pieces for 30 seconds with a load of 1 kg. Then, the state of the adhered pieces was observed, and the adhesion of the magnetic layer of the electromagnetic noise suppression sheet was evaluated as follows.

[0269] Evaluation A: The lower piece was not adhered when only the upper piece of the overlapped pieces was lifted

[0270] Evaluation B: The lower piece was adhered when only the upper piece of the overlapped pieces was lifted, but fell due to its own weight in less than 5 seconds

[0271] Evaluation C: The lower piece was adhered when only the upper piece of the overlapped pieces was lifted, and did not fall for 5 seconds or more

[0272] <Magnetic noise suppression effect>

[0273] The magnetic noise suppression effect of the electromagnetic noise suppression sheet produced was confirmed by evaluation based on the internal decoupling ratio (Rda) using an internal decoupling ratio measurement system (in accordance with IEC 62333-2) using a vector network analyzer and a loop antenna. Specifically, the internal decoupling ratio at 100 MHz and the frequency at the maximum internal decoupling ratio from 100 MHz to 10 GHz were measured.

[0274] The above results are shown in Table 1 and Table 2 together with the constituent materials of the magnetic layer of the electromagnetic noise suppression sheet produced.

[0275] [Table 1]

[0276]

[0277] [Table 2]

[0278]

[0279] As is clear from Table 1 and Table 2, in the electromagnetic noise suppression sheets of Examples 1 to 12, the magnetic noise suppression effect was confirmed, and furthermore, good results were obtained in terms of adhesion, flexibility, and tackiness. On the other hand, in the electromagnetic noise suppression sheets of Comparative Examples 1 to 4, the magnetic noise suppression effect was confirmed, but in Comparative Example 1 and Comparative Example 4, which did not contain the amorphous resin (a) having a glass transition temperature of 0°C or lower in the magnetic layer, the results were poor in terms of adhesion and flexibility, and in Comparative Example 2 and Comparative Example 3, which did not contain the amorphous resin (b) having a glass transition temperature of 10°C or higher in the magnetic layer, the results were poor in terms of tackiness.

[0280] With respect to the embodiments of the present application including the above Examples 1 to 12, the following supplementary modes are also disclosed.

[0281] Supplementary Mode 1: An electromagnetic noise suppression sheet comprising a substrate and a magnetic layer, characterized by,

[0282] the above magnetic layer comprises a magnetic material and a binder,

[0283] the above binder comprises an amorphous resin (A) having a glass transition temperature of -50°C to 0°C and an amorphous resin (B) having a glass transition temperature of 10°C or higher.

[0284] Supplementary Mode 2: The electromagnetic noise suppression sheet according to Supplementary Mode 1, wherein the above amorphous resin (A) is an amorphous polyester (a) having a glass transition temperature of -50°C to 0°C, and the above amorphous resin (B) is an amorphous polyester (b) having a glass transition temperature of 10°C or higher.

[0285] The electromagnetic noise suppression sheet according to any one of the above-mentioned embodiments 2 to 4, wherein the content ratio of the amorphous polyester (a) and the amorphous polyester (b) is (a):(b) = 95:5 to 35:65 in terms of mass ratio.

[0286] The electromagnetic noise suppression sheet according to the above-mentioned embodiment 2, wherein the content ratio of the amorphous polyester (a) and the amorphous polyester (b) is (a):(b) = 90:10 to 50:50 in terms of mass ratio.

[0287] The electromagnetic noise suppression sheet according to any one of the above-mentioned embodiments 2 to 4, wherein at least one of the amorphous polyester (a) and the amorphous polyester (b) contains a crosslinked portion crosslinked by an amide bond.

[0288] The electromagnetic noise suppression sheet according to any one of the above-mentioned embodiments 1 to 5, wherein the total amount of the amorphous resin (A) and the amorphous resin (B) is 90% by mass or more with respect to the total amount of the adhesive.

[0289] The electromagnetic noise suppression sheet according to any one of the above-mentioned embodiments 1 to 6, wherein the magnetic material contains a soft magnetic material.

[0290] The electromagnetic noise suppression sheet according to the above-mentioned embodiment 7, wherein the soft magnetic material is a carbonyl iron.

[0291] The electromagnetic noise suppression sheet according to the above-mentioned embodiment 7 or 8, wherein the volume content ratio of the soft magnetic material contained in the magnetic layer is 30 to 80%.

[0292] The electromagnetic noise suppression sheet according to any one of the above-mentioned embodiments 1 to 9, wherein the substrate is a resin film.

[0293] The electromagnetic noise suppression sheet according to any one of the above-mentioned embodiments 1 to 10, further comprising a metal layer.

[0294] The electromagnetic noise suppression sheet according to any one of the above-mentioned embodiments 1 to 11, wherein the entire thickness is 10 to 85 μm.

[0295] A method for manufacturing an electromagnetic noise suppression sheet according to any one of the above-mentioned embodiments 1 to 12, characterized by comprising:

[0296] a step of mixing a magnetic material, an amorphous resin (A) having a glass transition temperature of -50°C to 0°C, and an amorphous resin (B) having a glass transition temperature of 10°C or higher, together with a solvent to produce a magnetic layer forming paint, and

[0297] a step of applying the magnetic layer forming paint to a substrate and drying it.

[0298] Note 14: The electromagnetic noise suppression sheet production method according to Note 13, wherein the resin selected from at least one of the amorphous resin (A) and the amorphous resin (B) contained in the magnetic layer forming paint contains a carboxyl group.

[0299] Note 15: The electromagnetic noise suppression sheet production method according to Note 14, wherein the magnetic layer forming paint further contains a resin having at least one selected from an oxazoline group and a carbodiimide group as a crosslinking agent.

[0300] Note 16: The electromagnetic noise suppression sheet production method according to any one of Notes 13 to 15, wherein the solvent contained in the magnetic layer forming paint is at least one selected from water and a water-soluble solvent.

[0301] Note 17: A cable characterized by containing the electromagnetic noise suppression sheet according to any one of Notes 1 to 12.

[0302] The present application can also be implemented in a manner other than described above. The embodiments disclosed in the present application are examples and are not intended to be limiting. The scope of the present application is primarily explained by the appended claims, and all modifications within the scope of the claims equivalent to the claims are included in the claims.

[0303] Explanation of Reference Signs

[0304] 10, 10': electromagnetic noise suppression sheet, 11: substrate, 12: magnetic layer, 13: metal layer, 20, 30: coaxial cable, 21, 31: inner conductor, 22, 32: insulating layer, 23, 33: metal foil, 24, 34: metal braid, 25, 35: magnetic sheath layer, 35a: substrate layer, 35b: magnetic layer, 26, 36: outer covering layer.

Claims

1. An electromagnetic noise suppression sheet, comprising a substrate and a magnetic layer, characterized in that, The magnetic layer comprises magnetic material and adhesive. The adhesive comprises an amorphous resin (A) with a glass transition temperature of -50°C to 0°C and an amorphous resin (B) with a glass transition temperature of 10°C or higher.

2. The electromagnetic noise suppression sheet according to claim 1, wherein, The amorphous resin (A) is an amorphous polyester (a) with a glass transition temperature of -50℃ to 0℃. The amorphous resin (B) is an amorphous polyester (b) with a glass transition temperature of 10°C or higher.

3. The electromagnetic noise suppression sheet according to claim 2, wherein, The ratio of the amorphous polyester (a) and the amorphous polyester (b) by mass is (a):(b) = 95:5~35:

65.

4. The electromagnetic noise suppression sheet according to claim 2, wherein, The ratio of the amorphous polyester (a) and the amorphous polyester (b) by mass is (a):(b) = 90:10 to 50:

50.

5. The electromagnetic noise suppression sheet according to claim 2, wherein, At least one of the amorphous polyester (a) and the amorphous polyester (b) includes a crosslinked portion crosslinked by amide bonds.

6. The electromagnetic noise suppression sheet according to claim 1, wherein, The combined amount of the amorphous resin (A) and the amorphous resin (B) is 90% or more by mass relative to the total amount of the adhesive.

7. The electromagnetic noise suppression sheet according to claim 1, wherein, The magnetic material includes soft magnetic materials.

8. The electromagnetic noise suppression sheet according to claim 7, wherein, The soft magnetic material is carbonyl iron.

9. The electromagnetic noise suppression sheet according to claim 7, wherein, The volume content of the soft magnetic material contained in the magnetic layer is 30-80%.

10. The electromagnetic noise suppression sheet according to claim 1, wherein, The substrate is a resin film.

11. The electromagnetic noise suppression sheet according to claim 1, further comprising a metal layer.

12. The electromagnetic noise suppression sheet according to claim 1, wherein, The overall thickness is 10~85μm.

13. A method for manufacturing an electromagnetic noise suppression sheet, comprising the method for manufacturing the electromagnetic noise suppression sheet according to any one of claims 1 to 12, characterized in that, include: The process of preparing a coating for forming a magnetic layer by mixing magnetic materials, an amorphous resin (A) with a glass transition temperature of -50°C to 0°C, and an amorphous resin (B) with a glass transition temperature of 10°C or higher with a solvent, and... The process of applying the coating used to form the magnetic layer to a substrate and then drying it.

14. The method for manufacturing the electromagnetic noise suppression sheet according to claim 13, wherein, The resin selected from at least one of the amorphous resin (A) and the amorphous resin (B) contained in the coating for forming the magnetic layer contains a carboxyl group.

15. The method for manufacturing an electromagnetic noise suppression sheet according to claim 14, wherein, The coating for forming the magnetic layer further comprises a resin having at least one selected from oxazoline and carbodiimide as a crosslinking agent.

16. The method for manufacturing an electromagnetic noise suppression sheet according to claim 13, wherein, The solvent contained in the coating for forming the magnetic layer is selected from at least one of water and water-soluble solvents.

17. A cable, characterized in that, The electromagnetic noise suppression sheet includes any one of claims 1 to 12.

Images