Electromagnetic noise suppression sheet, cable in which same is used, and method for manufacturing electromagnetic noise suppression sheet

Abstract

An electromagnetic noise suppression sheet of the present application comprises a base material and a magnetic layer. The magnetic layer contains a soft magnetic material, a binder, and an organic silicon compound. The binder contains a hydrophilic resin. When the iron content (mass%) and the silicon content (mass%) of the surface of the magnetic layer are measured by scanning electron microscope-energy dispersive X-ray spectroscopy, the iron content (mass%) is represented by FeR, the silicon content (mass%) is represented by SiR, and the content ratio thereof is represented by SiR / Fer, the content ratio is in the range of 0.00<SiR / FeR≤0.60.

Description

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

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

[0002] With the development of wireless communication technology, exemplified by mobile phones, various devices and sensors are increasingly being connected to networks wirelessly. In the medical field, too, cordless devices are becoming more common from the perspective of infection prevention, and medical equipment is beginning to connect wirelessly. These communications require high speed and large capacity over relatively short distances, and therefore utilize high frequencies. As the number of devices using such high frequencies increases, the risk of malfunctions in electronic devices and communications due to electromagnetic noise generated by the devices or interference with the electromagnetic waves being used is also increasing. Furthermore, in recent years, millimeter-wave radar has begun to be installed in automobiles for the purpose of preventing collision accidents. Malfunctions in these medical and automotive devices can affect human lives, so they must not be allowed to operate. Therefore, there is a growing need to apply electromagnetic noise suppression sheets, as a measure to prevent malfunctions caused by electromagnetic noise and the resulting interference, also known as EMC (Electromagnetic Compatibility), to circuit elements and transmission lines that emit and receive electromagnetic waves in the MHz to GHz band.

[0003] By providing electromagnetic noise suppression sheets to society, we can contribute to achieving three of the 17 Sustainable Development Goals (SDGs) established by the United Nations: Goal 3 (Ensure healthy lives and promote well-being for all at all ages), Goal 9 (Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation), and Goal 12 (Ensure sustainable consumption and production patterns).

[0004] In this context, Patent Document 1 proposes using a laminate comprising a magnetic material layer containing magnetic powder and binder resin, and a polymer compound film layer, as a magnetic sheet that suppresses the transmission of electromagnetic waves. In Patent Document 1, the laminate is manufactured by applying a magnetic powder dispersion (magnetic layer forming coating) onto a polymer compound film layer which serves as a base material, drying it, and then performing pressure molding (calendar treatment). This pressure molding reduces air bubbles (voids) in the magnetic material layer and increases the magnetic permeability of the magnetic material layer.

[0005] On the other hand, when the magnetic layer is subjected to pressure treatment, the surface smoothness of the magnetic layer increases. When the manufactured magnetic sheet is wound up and stored, the number of true contact points increases at the contact surface of the magnetic sheet during winding, i.e., at the contact surface between the smooth magnetic layer surface and the originally smooth substrate surface or metal layer surface. Since adhesion due to intermolecular forces occurs at the true contact points, interlayer adhesion (blocking) between sheets is more likely to occur, making it difficult to unwind the sheet. In particular, when storing magnetic sheets wound up in high temperature or high temperature and high humidity environments, the above blocking is more likely to occur, so strict temperature and humidity control is required when storing magnetic sheets, which increases the burden of storage management.

[0006] Furthermore, prior art documents related to the electromagnetic noise suppression sheet of the present application include Patent Documents 2 and 3. Patent Document 2 discloses that the storage stability of a soft magnetic sheet can be improved by adding 0.1 to 5 parts by weight of silica powder per 100 parts by weight of the binder material to a soft magnetic sheet molded into a sheet shape using soft magnetic ferrite powder and a binder material. Patent Document 3 also discloses that the surface smoothness of a magnetic layer can be improved by adding a silicone-based surfactant to the magnetic layer of a magnetic recording medium.

[0007] Japanese Patent Publication No. 2016-36965, Japanese Patent Publication No. 2002-246224, Japanese Patent Publication No. 2000-11359

[0008] This invention solves the above problem and provides an electromagnetic noise suppression sheet that is less prone to blocking even when wound up and stored after manufacturing.

[0009] The electromagnetic noise suppression sheet of the present invention comprises a substrate and a magnetic layer, the magnetic layer comprises a soft magnetic material, a binder and an organosilicon compound, the binder comprises a hydrophilic resin, and when the iron content (mass%) and silicon content (mass%) on the surface of the magnetic layer are measured by scanning electron microscopy-energy dispersive X-ray spectroscopy, the iron content (mass%) is denoted as FeR, the silicon content (mass%) as SiR, and the content ratio is denoted as SiR / FeR, and the content ratio is in the range of 0.00 < SiR / FeR ≤ 0.60.

[0010] The cable of the present invention is characterized by including the electromagnetic noise suppression sheet of the present invention.

[0011] The present invention relates to a method for manufacturing an electromagnetic noise suppression sheet, comprising: a first step of mixing a soft magnetic material, a binder, an organosilicon compound, and a solvent to produce a magnetic layer forming coating; and a second step of applying the magnetic layer forming coating to a substrate and drying it to produce a magnetic layer / substrate laminated sheet.

[0012] According to this invention, by adding an organosilicon compound to the magnetic layer, it is possible to provide an electromagnetic noise suppression sheet that is less prone to blocking even when wound up and stored after manufacturing.

[0013] Figure 1 is a schematic cross-sectional view showing an example of an electromagnetic noise suppression sheet according to the embodiment. Figure 2 is a schematic cross-sectional view showing another example of an electromagnetic noise suppression sheet according to the embodiment. Figure 3 is a schematic cross-sectional view showing an example of a coaxial cable according to the embodiment.

[0014] (Electromagnetic Noise Suppression Sheet) An embodiment of the electromagnetic noise suppression sheet of the present invention will now be described. The electromagnetic noise suppression sheet of this embodiment includes a base material and a magnetic layer, the magnetic layer includes a soft magnetic material, a binder and an organosilicon compound, the binder includes a hydrophilic resin, and when the iron content (mass%) and silicon content (mass%) of the surface of the magnetic layer are measured by scanning electron microscopy-energy dispersive X-ray spectroscopy, if the iron content (mass%) is FeR and the silicon content (mass%) is SiR, and the content ratio is SiR / FeR, the content ratio is in the range of 0.00 < SiR / FeR ≤ 0.60.

[0015] In general, in electromagnetic noise suppression sheets consisting of a laminate of a magnetic layer and a substrate, when the fabricated electromagnetic noise suppression sheet is wound up and stored, interlayer adhesion (blocking) often occurs at the contact surface between the surface of the magnetic layer and the surface of the smoothly formed film substrate. This tendency becomes even more pronounced when the magnetic layer is subjected to pressure and heat treatment. When blocking occurs, the sheet may not be able to be unwound after being wound up, or even if it can be unwound, a part of the magnetic layer may adhere to the opposing substrate, causing the magnetic layer to peel off. Furthermore, the above-mentioned blocking can also occur with compositions that reduce the slipperiness (make it less slippery) of the magnetic layer surface, or with compositions that increase the viscosity of the magnetic layer.

[0016] Therefore, the inventors investigated a sheet configuration that could suppress blocking between the magnetic layer and the substrate, and found that by adding an organosilicon compound to the magnetic layer, blocking between the magnetic layer and the substrate facing the magnetic layer could be suppressed. The reason for this is currently considered to be as follows.

[0017] Generally, the magnetic layer of a magnetic sheet is formed by mixing a magnetic material, a resin, and a solvent to create a magnetic layer-forming coating, applying this coating to a substrate, and drying it. When an organosilicon compound is added to the magnetic layer-forming coating and applied to the substrate, the magnetic material, which has a higher specific gravity, moves towards the substrate, while the resin and organosilicon compound, which have a lower specific gravity than the magnetic material, move towards the surface of the magnetic layer, resulting in a resin / organosilicon-rich state near the surface of the magnetic layer. Even if the magnetic layer is subjected to pressurized heat treatment in this state, the organosilicon compound added to the magnetic layer and present near the surface of the magnetic layer remains there. It is believed that the presence of this organosilicon compound on the surface of the magnetic layer improves the surface slip properties of the magnetic layer, and even when the manufactured magnetic sheet is wound up and stored, adhesion at the true contact point between the magnetic layer and the substrate during winding is suppressed, thus preventing interlayer adhesion (blocking) between sheets.

[0018] As a result, even if the electromagnetic noise suppression sheet of this embodiment is rolled up and stored in a high-temperature or high-temperature, high-humidity environment, the above-mentioned blocking does not occur, eliminating the need for strict temperature and humidity control during storage and reducing the burden of storage management.

[0019] The electromagnetic noise suppression sheet of this embodiment will be described below with reference to the drawings. Figure 1 is a schematic cross-sectional view showing an example of the electromagnetic noise suppression sheet of this embodiment. In Figure 1, the electromagnetic noise suppression sheet 10 comprises a base material 11 and a magnetic layer 12 arranged on one main surface of the base material 11. In Figure 1, the electromagnetic noise suppression sheet 10 has a two-layer structure consisting of a base material 11 and a magnetic layer 12, but a three-layer structure may also be made by further arranging an adhesive layer on the magnetic layer 12 side.

[0020] Figure 2 is a schematic cross-sectional view showing another example of the electromagnetic noise suppression sheet of this embodiment. In Figure 2, the electromagnetic noise suppression sheet 20 comprises a base material 11, a magnetic layer 12 disposed on one main surface of the base material 11, and a metal layer 13 disposed on the other main surface of the base material 11. In Figure 2, the electromagnetic noise suppression sheet 20 has a three-layer structure consisting of a base material 11, a magnetic layer 12, and a metal layer 13, but it may also have a four-layer structure by further arranging an adhesive layer on the magnetic layer 12 side. Also, in Figure 2, an example is shown where the layers are arranged in the order of magnetic layer 12 / base material 11 / metal layer 13, but they may also be arranged in the order of magnetic layer 12 / metal layer 13 / base material 11.

[0021] The overall thickness of the electromagnetic noise suppression sheet in this embodiment is preferably 10 to 150 μm, and more preferably 30 to 120 μm. If the overall thickness of the electromagnetic noise suppression sheet is too thin, the thickness of the magnetic layer will also be thin, reducing the electromagnetic wave absorption capacity and the overall strength of the sheet. On the other hand, if the overall thickness of the electromagnetic noise suppression sheet is too thick, its flexibility will decrease, making it difficult to wrap around cables and connectors.

[0022] The electromagnetic noise suppression sheet of this embodiment may be used in sheet form, or it may be processed into a tape form for use. When the sheet is processed into a tape form, its width can be set appropriately according to the application. When the sheet is slit into a tape form, for example, the tape-shaped electromagnetic noise suppression sheet can be wound up and stored as described above.

[0023] Next, each component of the electromagnetic noise suppression sheet of this embodiment will be described.

[0024] <Magnetic Layer> The magnetic layer used in the electromagnetic noise suppression sheet of this embodiment comprises a magnetic material, a binder, and an organosilicon compound. The thickness of the magnetic layer is not particularly limited, but if it is too thin, the electromagnetic wave absorption will decrease, and if it is too thick, the flexibility will decrease, so it is usually set in the range of 10 μm or more and less than 100 μm. The constituent materials of the magnetic layer described above will be explained below.

[0025] [Organosilicon Compounds] The above organosilicon compounds preferably contain a siloxane structure. This is because the improvement in the surface slip properties of the magnetic layer by adding the above organosilicon compounds depends on the chemical structure of the organosilicon compounds, and it is thought that the higher the proportion of the siloxane structure, the higher the surface slip properties.

[0026] Furthermore, because the siloxane structure is hydrophobic, when a magnetic layer-forming coating containing a binder with a hydrophilic resin and an organosilicon compound having a siloxane structure is applied to a substrate, the hydrophobic siloxane structure portion of the organosilicon compound present on the surface of the applied coating film repels the hydrophilic resin and tends to rise to the surface of the coating film. In addition, due to the difference in specific gravity between the organosilicon compound and the magnetic powder, the organosilicon compound tends to move more easily to the surface of the magnetic layer, which is thought to reduce the surface tension of the magnetic layer surface. As a result, the surface slip properties of the magnetic layer are further improved, and the blocking resistance of the magnetic layer surface is further improved.

[0027] Examples of organosilicon compounds containing the above-mentioned siloxane structure include silicone-based organic compounds having a polydialkylsiloxane structure. Specifically, examples include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, and polyaralkyl-modified polydimethylsiloxane. Examples of commercially available product names for organosilicon compounds containing the above-mentioned siloxane structure include BYK-302, BYK-307, BYK-323, BYK-333, BYK-377, BYK-UV3500, BYK-UV3510, BYK-SILCLEAN3700, BYK-SILCLEAN3701, and BYK-SILCLEAN3720 from Bic Chemie, Polyflow KL-402 and KL-406 from Kyoeisha Chemical Co., Ltd., and LS280 from Kusumoto Chemical Co., Ltd.

[0028] Among the organosilicon compounds containing the siloxane structure described above, BYK-307 (trade name) and BYK-SILCLEAN3700 (trade name) are preferred. This is because they have a relatively large proportion of hydrophobic parts (siloxane structure parts), which makes them easily repelled by hydrophilic resins. When a magnetic layer-forming coating containing the organosilicon compound containing the siloxane structure, a hydrophilic resin, and a solvent is applied to a substrate and dried, the organosilicon compound present inside the coating film moves to the surface of the coating film on the upward current of the solvent within the coating film as the solvent evaporates, making it easier to float to the surface of the coating film.

[0029] Specifically, BYK-307 is mainly composed of polyether-modified polydimethylsiloxane, which has 45 to 230 siloxane bonds per molecule. It is thought that the number of siloxane bonds (hydrophobic parts) is greater than the number of polyether chains (hydrophilic parts) involved in the polyether modification. In addition, BYK-SILCLEAN3700 is mainly composed of hydroxyl group-containing silicon-modified acrylic, and it is thought that the proportion of polysiloxane structural parts (hydrophobic parts) that form the side chains is greater than the proportion of hydroxyl group-containing acrylic parts (hydrophilic parts) that form the main chain.

[0030] In particular, BYK-SILCLEAN3700 has a branched structure of linear polysiloxane structures (side chains) relative to the hydroxyl group-containing acrylic (main chain). This makes it easier for the linear polysiloxane structures (hydrophobic parts) to stand out on the surface of the coating, which is thought to improve the surface slip properties of the magnetic layer and the blocking resistance of the magnetic layer surface.

[0031] The volume content of the organosilicon compound in the magnetic layer is preferably 0.1% to 15%, and its mass percentage is preferably 0.03% to 4.5%. If the content of the organosilicon compound is too low, the proportion of the organosilicon compound present on the surface of the magnetic layer will decrease, making it easier for the sheets to block each other when the electromagnetic noise suppression sheet is rolled up and stored. On the other hand, if the content of the organosilicon compound is too high, the proportion of magnetic material in the magnetic layer will decrease, resulting in insufficient electromagnetic noise suppression effect of the magnetic layer.

[0032] Since the amount of organosilicon compounds contained in the magnetic layer is trace and difficult to measure directly after the magnetic layer is fabricated, in this application, a surface analysis of the magnetic layer is performed using a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), and the elemental composition of the magnetic layer surface is analyzed from the surface analysis results. The ratio of iron content (mass%) to silicon content (mass%) measured by this compositional analysis is used as a surrogate indicator of the organosilicon compound content (volume%) contained in the magnetic layer.

[0033] SEM-EDX is a technique that irradiates a sample with an electron beam, detects characteristic X-rays emitted from the sample, and performs elemental and compositional analysis by spectrally analyzing these characteristic X-rays by their energy. Since the characteristic X-rays detected by SEM-EDX have unique energy values ​​depending on the element, elemental analysis of the sample surface can be performed by measuring these values. Furthermore, compositional analysis of the sample surface can be performed by measuring the intensity of these characteristic X-rays. The detection depth by SEM-EDX is typically several nanometers to several micrometers, although this depends on the detected element and acceleration voltage.

[0034] Specifically, when the iron content (mass%) and silicon content (mass%) of the surface of the magnetic layer are measured by SEM-EDX, if the iron content (mass%) is denoted as FeR and the silicon content (mass%) as SiR, and the content ratio is denoted as SiR / FeR, then in this application, the content ratio (SiR / FeR) is set to the range of 0.00 < SiR / FeR ≤ 0.60.

[0035] When the value of SiR / FeR is 0, it means that the organosilicon compound is not contained in the surface portion of the magnetic layer, and the surface slipperiness of the magnetic layer cannot be improved. When the value of SiR / FeR exceeds 0, it means that the organosilicon compound is contained in the surface portion of the magnetic layer, the surface slipperiness of the magnetic layer is improved, and the antiblocking property is also improved. Here, when the value of SiR / FeR exceeds 0.60, it is considered that the surface slipperiness of the magnetic layer is further improved and the antiblocking property is also further improved. However, in this case, usually, the content of the organosilicon compound contained in the entire magnetic layer is also considered to be increased. Therefore, the proportion of the magnetic material in the magnetic layer decreases, and the electromagnetic noise suppression effect of the magnetic layer may become insufficient.

[0036] The above content ratio is preferably in the range of 0.14 ≤ SiR / FeR ≤ 0.53. Also, the single silicon content rate (mass%) of the surface of the magnetic layer measured by SEM-EDX is preferably 0.14% ≤ SiR, and more preferably 0.14% ≤ SiR ≤ 0.24%. Also, the single iron content rate (mass%) of the surface of the magnetic layer measured by SEM-EDX is preferably 40% ≤ FeR ≤ 60%, and more preferably 45% ≤ FeR ≤ 57%.

[0037] The above composition analysis of the surface of the magnetic layer using SEM-EDX was carried out by cutting the produced electromagnetic noise suppression sheet into a 2 mm × 2 mm square at an arbitrary position to obtain a measurement sample, observing the surface of the magnetic layer of this measurement sample with a scanning electron microscope (SEM) at a magnification of 50 times, and performing electron beam irradiation with Fe-Kα rays at an acceleration voltage of 15 kV on the observed SEM image using an energy dispersive fluorescent X-ray analyzer (EDX).

[0038] As the above SEM, a scanning electron microscope "S-3400" (product name) manufactured by Hitachi, Ltd. was used, and as the above EDX, an energy dispersive fluorescent X-ray analyzer "ULTIM (registered trademark) Max100" manufactured by Oxford Instruments was used.

[0039] The above-mentioned organosilicon compound only needs to be present at least on the surface of the magnetic layer, and its presence may be in a layered structure or partially present without a layered structure. In other words, it is sufficient that the organosilicon compound is contained within a specified range within the range detectable by SEM-EDX of the magnetic layer. Whether the organosilicon compound is present at least on the surface of the magnetic layer can be determined, for example, by analyzing the vicinity of the magnetic layer surface using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Furthermore, whether soft magnetic material and organosilicon compounds are present in the magnetic layer can be confirmed in advance by checking whether Fe and Si are detected in a known qualitative analysis.

[0040] [Soft Magnetic Materials] Magnetic materials include soft magnetic materials and hard magnetic materials, but in this embodiment, soft magnetic materials are used. Soft magnetic materials have high initial magnetic permeability and can exert an electromagnetic noise suppression effect even when included in small amounts in the magnetic layer, so the electromagnetic noise suppression effect can be exerted even when the magnetic layer is made into a thin film. In addition, since soft magnetic materials usually contain iron, the ratio of iron content (mass%) to silicon content (mass%) measured by SEM-EDX can be used as a substitute indicator for the content (volume%) of organosilicon compounds contained in the magnetic layer.

[0041] Examples of soft magnetic materials containing iron include iron, carbonyl iron powder, silicon iron, permalloy, permendur, soft ferrite, ferritic stainless steel, electromagnetic stainless steel, amorphous magnetic alloy, and nanocrystal magnetic alloy. In particular, Fe(CO) ５ Carbonyl iron powder represented by [formula] is preferred. This is because carbonyl iron powder can exhibit electromagnetic wave absorption performance (electromagnetic noise suppression effect) even in relatively high frequency ranges such as the GHz band.

[0042] The above-mentioned soft magnetic material is usually provided as a spherical or flattened powder, and its average particle size is preferably 3 μm to 50 μm, and more preferably 3 μm to 20 μm. The above-mentioned average particle size can be measured with a laser diffraction scattering particle size distribution analyzer. However, the powder of the above-mentioned magnetic material may be granular (irregular shape), needle-shaped, etc.

[0043] The above soft magnetic material preferably uses flattened soft magnetic powder. This is because using flattened soft magnetic powder improves the packing of the magnetic layer, increases the permeability of the magnetic layer, and improves the electromagnetic noise suppression effect of the magnetic layer.

[0044] Here, in this application, a flattened soft magnetic powder is defined as a soft magnetic powder whose flattening degree is 5.0 or greater, where the aspect ratio (short side length / thickness) is the ratio of the short side length of the flattened soft magnetic powder to the thickness of the flattened soft magnetic powder. Furthermore, the short side length of the flattened soft magnetic powder refers to the length of the minor axis of a hypothetical ellipse, assuming the soft magnetic powder is an ellipse when viewed from above. Furthermore, the thickness of the flattened soft magnetic powder refers to the length of the axis perpendicular to the hypothetical ellipsoid, from the intersection of the major and minor axes of the hypothetical ellipsoid.

[0045] The short side length and thickness of the above-mentioned soft magnetic powder are determined by observing the cross-section of the magnetic layer using SEM and taking the arithmetic mean of the short side length and thickness of any 100 soft magnetic powders in the observed image.

[0046] The volume content of the soft magnetic material contained in the magnetic layer is preferably 25 to 80%, and more preferably 27 to 70%. If the volume content is less than 25%, the electromagnetic noise suppression effect of the magnetic layer tends to be insufficient, and if it exceeds 80%, the proportion of binder in the magnetic layer decreases, reducing the strength of the magnetic layer and tending to cause cracks when the magnetic layer is bent. Furthermore, if the volume content is too high, the adhesion of the magnetic layer to the substrate decreases, and the magnetic material may fall off (fall out as powder) from the edges of the magnetic layer.

[0047] [Binder] The binder described above contains a hydrophilic resin. The hydrophilic resin can be a hydrophilic polyester, hydrophilic polyurethane, hydrophilic acrylic, etc., and it is particularly preferable that the hydrophilic resin be amorphous. Amorphous resins have high solubility in water and other solvents and excellent dispersibility of magnetic materials (magnetic powders). Therefore, by dispersing magnetic powders in a resin dissolved in water or other solvents, and then coating and drying it on a substrate to an arbitrary thickness, it is possible to form a magnetic layer into a sheet.

[0048] Furthermore, the hydrophilic resin more preferably comprises a plurality of amorphous hydrophilic resins with different glass transition temperatures, and more preferably comprises an amorphous hydrophilic resin (A) with a glass transition temperature of -50°C to 10°C and an amorphous hydrophilic resin (B) with a glass transition temperature of 50°C to 100°C.

[0049] By using an amorphous hydrophilic resin (A) with a glass transition temperature of -50°C to 10°C, flexibility can be imparted to the magnetic layer, and the adhesion of the magnetic layer to the substrate can also be improved. However, using only amorphous hydrophilic resin (A) can easily cause blocking in the magnetic layer, potentially causing the sheets to stick together when stacked or wound into a roll. On the other hand, using only amorphous hydrophilic resin (B) with a glass transition temperature of 50°C to 100°C makes the surface of the magnetic layer harder and less likely to stick, but this may reduce the adhesion between the magnetic layer and the substrate, and may cause cracking in the magnetic layer when used in a wound manner. For this reason, it is particularly preferable to use both amorphous hydrophilic resins (A) and (B) as the binder in this embodiment.

[0050] Furthermore, by using an amorphous hydrophilic resin (B) with a glass transition temperature of 50°C to 100°C, excessive blocking can be suppressed, and the magnetic layer can be given heat-sealability to general-purpose resins such as PVC (polyvinyl chloride) resin. On the other hand, if the glass transition temperature of the amorphous hydrophilic resin (B) is higher than 100°C, even if used in combination with an amorphous hydrophilic resin (A) with a glass transition temperature of -50°C to 10°C, the surface of the magnetic layer tends to harden, which can reduce the adhesion between the magnetic layer and the substrate, and the magnetic layer may crack easily when attached to uneven or curved surfaces, or when bent during wrapping.

[0051] Here, even when the amorphous hydrophilic resins (A) and (B) are used in combination, the glass transition temperature (Tg) refers to the unique glass transition temperature of each of the amorphous hydrophilic resins (A) and (B), and the glass transition temperatures of each resin are temperatures measured separately by differential scanning calorimetry (DSC) as specified in JIS K 7121-1987.

[0052] As the amorphous hydrophilic resin (A), amorphous hydrophilic polyester, amorphous hydrophilic polyurethane, amorphous hydrophilic acrylic, etc., having a glass transition temperature of -50°C to 10°C can be used, and as the amorphous hydrophilic resin (B), amorphous hydrophilic polyester, amorphous hydrophilic polyurethane, amorphous hydrophilic acrylic, etc., having a glass transition temperature of 50°C to 100°C can be used. Among these, amorphous hydrophilic polyester (a) with a glass transition temperature of -50°C to 10°C is particularly preferred as amorphous hydrophilic resin (A), and amorphous hydrophilic polyester (b) with a glass transition temperature of 50°C to 100°C is preferred as amorphous hydrophilic resin (B). Among amorphous hydrophilic resins, amorphous hydrophilic polyester has excellent solubility and flexibility and is suitable for manufacturing sheet-like magnetic layers.

[0053] From the above viewpoint, the content ratio of the amorphous hydrophilic polyester (a) and the amorphous hydrophilic polyester (b) is preferably (a):(b) = 95:5 to 35:65 by mass ratio, and more preferably (a):(b) = 90:10 to 50:50.

[0054] Examples of the amorphous hydrophilic polyesters (a) and (b) mentioned above include "Byron" (registered trademark) manufactured by Toyobo Co., Ltd., "Pluscoat" (registered trademark) manufactured by Go-O Chemical Co., Ltd., "Nichigo Polyester" (registered trademark) manufactured by Mitsubishi Chemical Corporation, and "Almatex" (registered trademark) manufactured by Mitsui Chemicals, Inc. Since these have excellent solubility in water and organic solvents, they can be used by dissolving them in water or organic solvents in any proportion.

[0055] In addition to the amorphous hydrophilic resin (A) and the amorphous hydrophilic resin (B), the above-mentioned binder may also contain at least one of a crystalline resin and an amorphous hydrophilic resin having a glass transition temperature greater than 10°C and less than 50°C, to the extent that it does not impair the effects of the present invention. In that case, the total amount of the amorphous hydrophilic resin (A) and the amorphous hydrophilic resin (B) is preferably 90% by mass or more, and more preferably 95% by mass or more, of the total amount of the binder.

[0056] [Other materials] The magnetic layer contains Al to an extent that does not affect the effects of the present invention.２ O ３ (alumina), ZrO ２ (zirconia), CuO, MgO (magnesia), Y ２ O ３ , ZnO, CaO, TiO ２ (titania), BeO, ThO ２ , Cr ２ O ３ , SnO ２ , CeO ２ , B ２ O ３ , Na ２ O, K[[ID=2⑧]] ２ O, PbO, Li ２ O, barium titanate, lead zirconate titanate, etc. may be included in the particles (fillers).

[0057] <Base material> The base material used for the electromagnetic noise suppression sheet of this embodiment is a substrate for forming a magnetic layer.

[0058] The above-mentioned substrate can be any material that is flexible and can ensure adhesion to the magnetic layer, and is usually a resin film. Examples of resins that make up the above-mentioned substrate include polyolefin resins (polyethylene, polypropylene, etc.), polyester resins (polyethylene terephthalate: PET, polyethylene naphthalate: PEN, polybutylene terephthalate: PBT, polybutylene naphthalate: PBN, etc.), polyimide resins, polyamide resins, ethylene-vinyl acetate copolymers, ionomer resins, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester copolymers, ethylene-butene copolymers, ethylene-hexene copolymers, polyurethane resins, polyetherketone resins, polyether resins, polyethersulfone resins, polystyrene resins (polystyrene, etc.), polyvinyl chloride resins, polyvinylidene chloride resins, polyvinyl alcohol resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate copolymers, polycarbonate resins, fluororesins, silicone resins, cellulose resins, and crosslinked products of these resins. Among these, polyethylene terephthalate (PET) is more preferred in terms of mechanical properties and cost. One or more of these resin materials can be used. Furthermore, the above resin materials may have functional groups as needed. Functional monomers or modifier monomers may also be grafted onto the resin material.

[0059] The surface of the above-mentioned substrate may be subjected to known surface treatments to improve adhesion with adjacent magnetic layers. Specific examples of such surface treatments include corona discharge treatment, ozone exposure treatment, high-voltage electric shock exposure treatment, and ionization radiation treatment. Furthermore, the substrate may be subjected to coating treatments with undercoating agents (such as silicone treatment), primer treatment, matting treatment, crosslinking treatment, etc.

[0060] The above-mentioned substrate may be a single layer or a laminate of two or more layers. Furthermore, known auxiliary agents such as fillers, flame retardants, degradation inhibitors, antistatic agents, softeners, and plasticizers may be added to the substrate as needed.

[0061] The thickness of the above-mentioned substrate is not particularly limited, but is preferably 5 to 20 μm, and more preferably 10 to 15 μm. If the thickness of the above-mentioned substrate is within the above range, both strength and flexibility can be achieved in the electromagnetic noise suppression sheet of this embodiment.

[0062] Since the above-mentioned substrate only needs to be flexible and capable of ensuring adhesion with the magnetic layer, a metal layer such as a metal foil, as described later, can be used as the substrate instead of the resin film. That is, a metal layer, as described later, can be used as the substrate 11 in Figure 1.

[0063] <Metal Layer> As shown in Figure 2, by placing a metal layer on the electromagnetic noise suppression sheet of this embodiment, the electromagnetic noise suppression sheet can be given electric field shielding performance, and not only magnetic noise but also electrical noise can be suppressed.

[0064] The type of metal constituting the above metal layer is not particularly limited as long as it has some degree of flexibility, but aluminum, copper, permalloy, etc. are preferred. Among aluminum, soft aluminum and among copper, rolled copper are more preferred because they have high conductivity, are inexpensive, are easy to process into thin films, and have excellent flexibility. In addition, permalloy has high magnetic collection effect in the kHz range in addition to conductivity, and can also be used as a magnetic shield.

[0065] The thickness of the above-mentioned metal layer is not particularly limited, but if it is too thick, the flexibility will decrease, so it is usually set in the range of 0.1 to 30 μm.

[0066] (Method for Manufacturing an Electromagnetic Noise Suppression Sheet) An embodiment of the method for manufacturing the electromagnetic noise suppression sheet of the present invention will now be described. The method for manufacturing the electromagnetic noise suppression sheet of this embodiment is a method for manufacturing the electromagnetic noise suppression sheet of the present invention described above, and is characterized by comprising: a first step of mixing a soft magnetic material, a binder, an organosilicon compound, and a solvent to produce a magnetic layer forming coating; and a second step of applying the magnetic layer forming coating to a substrate and drying it to produce a magnetic layer / substrate laminated sheet.

[0067] <Paint for forming a magnetic layer> The above-mentioned paint for forming a magnetic layer can be prepared by mixing a soft magnetic material, a binder, an organosilicon compound, and a solvent.

[0068] The soft magnetic material and binder described above are the same as those that constitute the magnetic layer of the electromagnetic noise suppression sheet in the embodiment of the present invention described above.

[0069] Examples of solvents that can be used include water, ethyl alcohol, methyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, ethylene glycol, propylene glycol, methyl ethyl ketone, ethyl acetate, toluene, and the like.

[0070] The content of the above solvent is not particularly limited, but it should be 50.0% by mass or more and 99.5% by mass or less, relative to the total mass of the magnetic layer forming coating.

[0071] The above-mentioned coating for forming a magnetic layer may further contain surface modifiers, defoamers, thickeners, etc.

[0072] <Formation of Magnetic Layer> As a method for applying the above-mentioned magnetic layer-forming coating onto the substrate, for example, coating methods such as bar coating, reverse coating, gravure coating, microgravure® coating, die coating, dipping, spin coating, slit coating, and spray coating can be used.

[0073] The drying after coating as described above can be carried out under conditions that allow the solvent component of the magnetic layer-forming coating to evaporate, and is preferably done at 80 to 150°C for 3 to 30 minutes. If solvent remains in the magnetic layer, the strength tends to be inferior. Drying methods include, for example, hot air drying, heating drying, vacuum drying, and natural drying.

[0074] After the second step described above, the magnetic layer / substrate laminated sheet may be subjected to pressurized heat treatment. This pressurized heat treatment can be carried out using a metal roll or a resin roll. Furthermore, if the magnetic layer is formed on a single sheet, the pressurized heat treatment can be performed by press working. The pressurized heat treatment is preferably carried out at a temperature above the glass transition temperature (Tg) of the binder resin used in the formed magnetic layer, and more preferably at a temperature 20°C or higher than Tg. The pressure for the pressurized heat treatment is preferably 250 kg / cm or higher in the case of calendering using a metal roll or a resin roll. In the case of press working, 200 kg / cm is preferable. ２ The above pressure is preferable. The calendering and pressing processes may be performed multiple times.

[0075] (Cable) Embodiments of the cable of this application will now be described. The cable of this embodiment is characterized by comprising the electromagnetic noise suppression sheet of the embodiment of this application described above. The cable of this embodiment includes coaxial cables, twisted pair cables, multi-core cables, etc. In particular, coaxial cables are used for high-frequency transmission and are used for video cable applications.

[0076] The following describes a coaxial cable, which is one of the cables in this embodiment, based on the drawings. In the coaxial cable described below, the electromagnetic noise suppression sheet of this application is used as the electromagnetic noise suppression layer of the coaxial cable.

[0077] Figure 3 is a schematic cross-sectional view showing an example of a coaxial cable according to this embodiment. The coaxial cable 30 comprises an internal conductor 31, an insulating layer 32, a metal foil 33, a metal braid 34, an electromagnetic noise suppression layer 35, and an outer covering layer 36. The electromagnetic noise suppression layer 35 uses the electromagnetic noise suppression sheet of the present invention described above, and the electromagnetic noise suppression layer 35 is composed of a base layer 35a and a magnetic layer 35b arranged on one side of the base layer 35a.

[0078] In Figure 3, the magnetic layer 35b of the electromagnetic noise suppression layer 35 is positioned on the axial side, but the base material layer 35a may also be positioned on the axial side.

[0079] The electromagnetic noise suppression layer 35 of the coaxial cable 30 can be formed by wrapping the electromagnetic noise suppression sheet of this invention around the outer surface of a linear conductor consisting of an internal conductor 31, an insulating layer 32, a metal foil 33, and a metal braid 34. This allows for a thinner electromagnetic noise suppression layer and shorter processing time.

[0080] The present application will be described in detail below using examples. However, the present application is not limited to the following examples. Unless otherwise specified, "parts" below means "parts by mass".

[0081] (Example 1) <Preparation of magnetic layer forming coating> Magnetic layer forming coating A was prepared by mixing and dispersing the following components. (1) Soft magnetic material (flattened reduced carbonyl iron powder manufactured by Tenichi Co., Ltd., trade name "RPZ"): 43.8 parts (2) Organosilicon compound solution (hydroxyl group-containing silicon-modified acrylic manufactured by Bic Chemie, trade name "BYK-SILCLEAN3700", solids concentration: 25% by mass, solvent: methoxypropyl acetate): 0.10 parts (3) Amorphous hydrophilic polyester resin solution (a1) (manufactured by Toyobo MC Co., Ltd., trade name "Byron BX-1001", resin Tg: -18°C, solids concentration: 43% by mass, solvent: methyl ethyl ketone): 7.7 parts (4) Amorphous hydrophilic polyester resin solution (a2) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 630", resin Tg: 7°C, solids concentration: 42% by mass, solvent: methyl ethyl ketone): 5.2 parts (5) Amorphous hydrophilic polyester resin solution (b) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 200", resin Tg: 67°C, solids concentration: 46% by mass, solvent: methyl ethyl ketone): 11.8 parts (6) Crosslinking agent (polyisocyanate for paints / non-yellowing type, manufactured by Tosoh Corporation, trade name "Coronate® HX"): 0.20 parts (7) Solvent (methyl ethyl ketone): 31.2 parts

[0082] The volume content of the soft magnetic material was 39% and the volume content of the organosilicon compound was 0.17% relative to the total solid content of the magnetic layer-forming coating A described above.

[0083] <Formation of Magnetic Layer> Next, an electromagnetic noise suppression sheet of Example 1 was produced using a PET film with a thickness of 12 μm (manufactured by Toyobo Co., Ltd., product name "Toyobo Ester® Film E5102") as a substrate. The magnetic layer forming coating A was applied to one main surface of the substrate using an applicator, and after drying at 140°C for 5 minutes, it was subjected to pressurized heat treatment to form a magnetic layer on one main surface. The thickness of the magnetic layer was 50 μm.

[0084] <Compositional Analysis of the Magnetic Layer by SEM-EDX> Next, the surface composition of the magnetic layer was analyzed using SEM-EDX. This SEM-EDX analysis of the magnetic layer surface was performed by cutting the fabricated electromagnetic noise suppression sheet into 2 mm x 2 mm squares at arbitrary locations to create measurement samples. The surface of the magnetic layer of these measurement samples was observed at a magnification of 50x using a scanning electron microscope (SEM), and the observed SEM image was irradiated with Fe-Kα electrons at an acceleration voltage of 15 kV using an energy-dispersive X-ray fluorescence analyzer (EDX).

[0085] For the above-mentioned SEM, we used the "S-3400" scanning electron microscope (product name) manufactured by Hitachi, Ltd., and for the above-mentioned EDX, we used the "ULTIM® Max100" energy-dispersive X-ray fluorescence analyzer manufactured by Oxford Corporation.

[0086] The ratio of iron content (FeR mass%) to silicon content (SiR mass%) on the surface of the magnetic layer, as measured by the above SEM-EDX, was 0.31 (SiR / FeR).

[0087] (Example 2) <Preparation of magnetic layer forming coating> Magnetic layer forming coating B was prepared by mixing and dispersing the following components. (1) Soft magnetic material (flattened reduced carbonyl iron powder manufactured by Tenichi Co., Ltd., trade name "RPZ"): 43.8 parts (2) Organosilicon compound solution (hydroxyl group-containing silicon-modified acrylic manufactured by Bic Chemie, trade name "BYK-SILCLEAN3700", solids concentration: 25% by mass, solvent: methoxypropyl acetate): 2.9 parts (3) Amorphous hydrophilic polyester resin solution (a1) (manufactured by Toyobo MC Co., Ltd., trade name "Byron BX-1001", resin Tg: -18°C, solids concentration: 43% by mass, solvent: methyl ethyl ketone): 7.0 parts (4) Amorphous hydrophilic polyester resin solution (a2) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 630", resin Tg: 7°C, solids concentration: 42% by mass, solvent: methyl ethyl ketone): 4.7 parts (5) Amorphous hydrophilic polyester resin solution (b) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 200", resin Tg: 67°C, solids concentration: 46% by mass, solvent: methyl ethyl ketone): 10.7 parts (6) Crosslinking agent (polyisocyanate for paints / non-yellowing type, manufactured by Tosoh Corporation, trade name "Coronate® HX"): 0.19 parts (7) Solvent (methyl ethyl ketone): 31.9 parts

[0088] The volume content of the soft magnetic material was 37% and the volume content of the organosilicon compound was 4.8% relative to the total solid content of the magnetic layer-forming coating B described above.

[0089] <Formation of Magnetic Layer> Next, an electromagnetic noise suppression sheet of Example 2 was prepared in the same manner as in Example 1, except that the magnetic layer-forming coating B described above was used, and a magnetic layer was formed on one main surface of the substrate. The thickness of the magnetic layer was 50 μm. Also, the ratio of iron content (FeR mass%) to silicon content (SiR mass%) on the surface of the magnetic layer, measured by SEM-EDX in the same manner as in Example 1, was 0.37 (SiR / FeR).

[0090] (Example 3) <Preparation of magnetic layer forming coating> Magnetic layer forming coating C was prepared by mixing and dispersing the following components. (1) Soft magnetic material (flattened reduced carbonyl iron powder manufactured by Tenichi Co., Ltd., trade name "RPZ"): 39.8 parts (2) Organosilicon compound solution (hydroxyl group-containing silicon-modified acrylic manufactured by Bic Chemie, trade name "BYK-SILCLEAN 3700", solids concentration: 25% by mass, solvent: methoxypropyl acetate): 9.1 parts (3) Amorphous hydrophilic polyester resin solution (a1) (manufactured by Toyobo MC Co., Ltd., trade name "Byron BX-1001", resin Tg: -18°C, solids concentration: 43% by mass, solvent: methyl ethyl ketone): 5.4 parts (4) Amorphous hydrophilic polyester resin solution (a2) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 630", resin Tg: 7°C, solids concentration: 42% by mass, solvent: methyl ethyl ketone): 3.7 parts (5) Amorphous hydrophilic polyester resin solution (b) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 200", resin Tg: 67°C, solids concentration: 46% by mass, solvent: methyl ethyl ketone): 8.3 parts (6) Crosslinking agent (polyisocyanate for paints / non-yellowing type, manufactured by Tosoh Corporation, trade name "Coronate® HX"): 0.18 parts (7) Solvent (methyl ethyl ketone): 33.5 parts

[0091] The volume content of the soft magnetic material was 33% and the volume content of the organosilicon compound was 14.3% relative to the total solid content of the magnetic layer-forming coating C described above.

[0092] <Formation of Magnetic Layer> Next, an electromagnetic noise suppression sheet of Example 3 was prepared in the same manner as in Example 1, except that the magnetic layer-forming coating C described above was used, and a magnetic layer was formed on one main surface of the substrate. The thickness of the magnetic layer was 50 μm. Also, the ratio of iron content (FeR mass%) to silicon content (SiR mass%) on the surface of the magnetic layer, measured by SEM-EDX in the same manner as in Example 1, was 0.53 (SiR / FeR).

[0093] (Example 4) <Preparation of magnetic layer forming coating> Magnetic layer forming coating D was prepared by mixing and dispersing the following components. (1) Soft magnetic material (flattened reduced carbonyl iron powder manufactured by Tenichi Co., Ltd., trade name "RPZ"): 43.7 parts (2) Organosilicon compound solution (polyether-modified polydimethylsiloxane manufactured by Bic Chemie, trade name "BYK-307", solids concentration: 97% by mass or more): 0.20 parts (3) Amorphous hydrophilic polyester resin solution (a1) (manufactured by Toyobo MC Co., Ltd., trade name "Byron BX-1001", resin Tg: -18°C, solids concentration: 43% by mass, solvent: methyl ethyl ketone): 7.6 parts (4) Amorphous hydrophilic polyester resin solution (a2) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 630", resin Tg: 7°C, solids concentration: 42% by mass, solvent: methyl ethyl ketone): 5.1 parts (5) Amorphous hydrophilic polyester resin solution (b) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 200", resin Tg: 67°C, solids concentration: 46% by mass, solvent: methyl ethyl ketone): 11.6 parts (6) Crosslinking agent (polyisocyanate for paints / non-yellowing type, manufactured by Tosoh Corporation, trade name "Coronate® HX"): 0.20 parts (7) Solvent (methyl ethyl ketone): 31.5 parts

[0094] The volume content of the soft magnetic material was 38% and the volume content of the organosilicon compound was 1.28% relative to the total solid content of the magnetic layer-forming coating D described above.

[0095] <Formation of Magnetic Layer> Next, an electromagnetic noise suppression sheet of Example 4 was prepared in the same manner as in Example 1, except that the magnetic layer-forming coating D described above was used, and a magnetic layer was formed on one main surface of the substrate. The thickness of the magnetic layer was 50 μm. Also, the ratio of iron content (FeR mass%) to silicon content (SiR mass%) on the surface of the magnetic layer, measured by SEM-EDX in the same manner as in Example 1, was 0.36 (SiR / FeR).

[0096] (Example 5) <Preparation of magnetic layer forming coating> Magnetic layer forming coating E was prepared by mixing and dispersing the following components. (1) Soft magnetic material (spherical reduced carbonyl iron powder manufactured by Tenichi Co., Ltd., trade name "YW-3"): 70 parts (2) Organosilicon compound solution (hydroxyl group-containing silicon-modified acrylic manufactured by Bic Chemie Co., Ltd., trade name "BYK-SILCLEAN3700", solids concentration: 25% by mass, solvent: methoxypropyl acetate): 2.9 parts (3) Amorphous hydrophilic polyester resin solution (a1) (manufactured by Toyobo MC Co., Ltd., trade name "Byron BX-1001", resin Tg: -18°C, solids concentration: 43% by mass, solvent: methyl ethyl ketone): 5.6 parts (4) Amorphous hydrophilic polyester resin solution (a2) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 630", resin Tg: 7°C, solids concentration: 42% by mass, solvent: methyl ethyl ketone): 5.0 parts (5) Amorphous hydrophilic polyester resin solution (b) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 200", resin Tg: 67°C, solids concentration: 46% by mass, solvent: methyl ethyl ketone): 12.5 parts (6) Crosslinking agent (polyisocyanate for paints / non-yellowing type, manufactured by Tosoh Corporation, trade name "Coronate® HX"): 0.2 parts (7) Solvent (methyl ethyl ketone): 3.8 parts

[0097] The volume content of the soft magnetic material was 58% and the volume content of the organosilicon compound was 4.8% relative to the total solid content of the magnetic layer-forming coating E described above.

[0098] <Formation of Magnetic Layer> Next, an electromagnetic noise suppression sheet of Example 5 was prepared in the same manner as in Example 1, except that the magnetic layer-forming coating E was used, and a magnetic layer was formed on one main surface of the substrate. The thickness of the magnetic layer was 50 μm. Also, the ratio of iron content (FeR mass%) to silicon content (SiR mass%) on the surface of the magnetic layer, measured by SEM-EDX in the same manner as in Example 1, was 0.14 (SiR / FeR).

[0099] (Comparative Example 1) <Preparation of Magnetic Layer Forming Coating> Magnetic layer forming coating F was prepared by mixing and dispersing the following components. (1) Soft magnetic material (spherical reduced carbonyl iron powder manufactured by Tenichi Co., Ltd., trade name "YW-3"): 72.1 parts (2) Amorphous hydrophilic polyester resin solution (a1) (manufactured by Toyobo MC Co., Ltd., trade name "Byron BX-1001", resin Tg: -18°C, solids concentration: 43% by mass, solvent: methyl ethyl ketone): 5.8 parts (3) Amorphous hydrophilic polyester resin solution (a2) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 630", resin Tg: 7°C, solids concentration: 42% by mass, solvent: methyl ethyl ketone): 5.1 parts (4) Amorphous hydrophilic polyester resin solution (b) (manufactured by Toyobo MC Co., Ltd., trade name "Byron 200", resin Tg: 67°C, solids concentration: 46% by mass, solvent: methyl ethyl ketone): 12.9 parts (5) Crosslinking agent (polyisocyanate for paints / non-yellowing type, manufactured by Tosoh Corporation, trade name "Coronate® HX"): 0.2 parts (6) Solvent (methyl ethyl ketone): 3.9 parts

[0100] The volume content of the soft magnetic material was 60% of the total solid content of the magnetic layer-forming coating F described above, and the volume content of the organosilicon compound was 0%.

[0101] <Formation of Magnetic Layer> Next, an electromagnetic noise suppression sheet of Comparative Example 1 was prepared in the same manner as in Example 1, except that the magnetic layer-forming coating F described above was used, and a magnetic layer was formed on one main surface of the substrate. The thickness of the magnetic layer was 50 μm. Also, the ratio of iron content (FeR mass%) to silicon content (SiR mass%) (SiR / FeR) on the surface of the magnetic layer, measured by SEM-EDX in the same manner as in Example 1, was 0.

[0102] The electromagnetic noise suppression sheets of Examples 1 to 5 and Comparative Example 1 described above were subjected to blocking tests as follows, and their blocking properties were evaluated.

[0103] <Blocking Test> Two 5cm square pieces of the fabricated electromagnetic noise suppression sheet were prepared. The magnetic layer surface of one sheet was placed in contact with the substrate surface of the other sheet, and the stacked sheets were then sandwiched between two glass plates to create the evaluation sample. Next, under temperatures of 60°C and 70°C, 40 g / cm³ was applied to the magnetic layer side of the measurement sample. ２ The load was applied for 60 hours. Afterwards, the adhesion state of the stacked sheets was observed, and the blocking properties of the magnetic layer of the electromagnetic noise suppression sheet were evaluated.

[0104] <Evaluation Criteria for Blocking Properties> The blocking properties were evaluated according to the following criteria. Evaluation A: When the stacked sheets were separated into their original sheets, no damage such as peeling occurred to the magnetic layer that was facing the substrate. Evaluation B: When the stacked sheets were separated into their original sheets, even partial damage such as peeling occurred to the magnetic layer that was facing the substrate.

[0105] The results of the above blocking performance evaluation are shown in Table 1, along with the type and volume content of the soft magnetic material in the magnetic layer, the type and volume content of the organosilicon compound, and the SiR / FeR value of the magnetic layer surface measured by SEM-EDX.

[0106]

[0107] Table 1 shows that in Examples 1 to 5, where an organosilicon compound was added to the magnetic layer, blocking was prevented even in a high-temperature environment of 60°C. Furthermore, in Examples 1 to 3 and Example 5, where an organosilicon compound was added to the magnetic layer, blocking was prevented even in an even higher-temperature environment of 70°C.

[0108] On the other hand, in Comparative Example 1, which did not contain an organosilicon compound in the magnetic layer, blocking could not be prevented at either 60°C or 70°C.

[0109] Furthermore, all of Examples 1 to 5 exhibited heat-sealing properties to PVC film. This indicates that Examples 1 to 5 achieve both heat-sealing properties and blocking resistance.

[0110] With respect to embodiments of the present application including the above-described Examples 1 to 5, the following appendix embodiments are further disclosed. (Appendix Embodiment 1) An electromagnetic noise suppression sheet comprising a substrate and a magnetic layer, wherein the magnetic layer comprises a soft magnetic material, a binder and an organosilicon compound, the binder comprises a hydrophilic resin, and when the iron content (mass%) and silicon content (mass%) of the surface of the magnetic layer are measured by scanning electron microscopy-energy dispersive X-ray spectroscopy, the iron content (mass%) is defined as FeR, the silicon content (mass%) as SiR, and the content ratio is defined as SiR / FeR, characterized in that the content ratio is in the range of 0.00 < SiR / FeR ≤ 0.60. (Appendix Embodiment 2) The electromagnetic noise suppression sheet according to Appendix Embodiment 1, wherein the content ratio is in the range of 0.14 ≤ SiR / FeR ≤ 0.53. (Appendix 3) An electromagnetic noise suppression sheet according to appendix 1 or 2, wherein the organosilicon compound comprises a siloxane structure. (Appendix 4) An electromagnetic noise suppression sheet according to any one of appendix 1 to 3, wherein the organosilicon compound has 45 to 230 siloxane bonds per molecule. (Appendix 5) An electromagnetic noise suppression sheet according to any one of appendix 1 to 4, wherein the organosilicon compound comprises a linear polysiloxane structure as a branched structure relative to the main chain. (Appendix 6) An electromagnetic noise suppression sheet according to any one of appendix 1 to 5, wherein the soft magnetic material comprises carbonyl iron powder. (Appendix 7) An electromagnetic noise suppression sheet according to any one of appendix 1 to 6, wherein the soft magnetic material has a flattened shape. (Appendix 8) An electromagnetic noise suppression sheet according to any one of appendix 1 to 7, wherein the hydrophilic resin is amorphous. (Appendix 9) An electromagnetic noise suppression sheet according to any of Appendix 1 to 8, wherein the hydrophilic resin comprises a plurality of amorphous hydrophilic resins with different glass transition temperatures. (Appendix 10) An electromagnetic noise suppression sheet according to any of Appendix 1 to 9, wherein the substrate is a resin film. (Appendix 11) An electromagnetic noise suppression sheet according to any of Appendix 1 to 10, further comprising a metal layer. (Appendix 12) A cable characterized by comprising an electromagnetic noise suppression sheet according to any of Appendix 1 to 11.(Appendix Form 13) A method for manufacturing an electromagnetic noise suppression sheet according to any of the appendix forms 1 to 11, comprising: a first step of mixing a soft magnetic material, a binder, an organosilicon compound, and a solvent to produce a magnetic layer forming coating; and a second step of applying the magnetic layer forming coating to a substrate and drying it to produce a magnetic layer / substrate laminated sheet.

[0111] This application can also be implemented in forms other than those described above. The embodiments disclosed herein are examples and are not limiting. The scope of this application shall be interpreted in accordance with the claims attached, which take precedence over the description in the above specification, and all modifications within the scope equivalent to the claims shall be included in the claims.

[0112] 10, 20 Electromagnetic noise suppression sheet 11 Base material 12 Magnetic layer 13 Metal layer 30 Coaxial cable 31 Internal conductor 32 Insulation layer 33 Metal foil 34 Metal braid 35 Electromagnetic noise suppression layer 35a Base material layer 35b Magnetic layer 36 Outer covering layer

Claims

1. An electromagnetic noise suppression sheet comprising a substrate and a magnetic layer, wherein the magnetic layer comprises a soft magnetic material, a binder, and an organosilicon compound, the binder comprises a hydrophilic resin, and when the iron content (mass%) and silicon content (mass%) of the surface of the magnetic layer are measured by scanning electron microscopy-energy dispersive X-ray spectroscopy, the iron content (mass%) is denoted as FeR, the silicon content (mass%) as SiR, and the content ratio is denoted as SiR / FeR, and the content ratio is in the range of 0.00 < SiR / FeR ≤ 0.

60.

2. The electromagnetic noise suppression sheet according to claim 1, wherein the content ratio is in the range of 0.14 ≤ SiR / FeR ≤ 0.

53.

3. The electromagnetic noise suppression sheet according to claim 1, wherein the organosilicon compound includes a siloxane structure.

4. The electromagnetic noise suppression sheet according to claim 1, wherein the organosilicon compound has 45 to 230 siloxane bonds per molecule.

5. The electromagnetic noise suppression sheet according to claim 1, wherein the organosilicon compound includes a linear polysiloxane structure as a branched structure relative to the main chain.

6. The electromagnetic noise suppression sheet according to claim 1, wherein the soft magnetic material comprises carbonyl iron powder.

7. The electromagnetic noise suppression sheet according to claim 1, wherein the soft magnetic material has a flattened shape.

8. The electromagnetic noise suppression sheet according to claim 1, wherein the hydrophilic resin is amorphous.

9. The electromagnetic noise suppression sheet according to claim 1, wherein the hydrophilic resin comprises a plurality of amorphous hydrophilic resins with different glass transition temperatures.

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. A cable characterized by including an electromagnetic noise suppression sheet according to any one of claims 1 to 11.

13. A method for manufacturing an electromagnetic noise suppression sheet according to any one of claims 1 to 11, comprising: a first step of mixing a soft magnetic material, a binder, an organosilicon compound, and a solvent to produce a magnetic layer forming coating; and a second step of applying the magnetic layer forming coating to a substrate and drying it to produce a magnetic layer / substrate laminated sheet.

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