JP2006032929A5 - - Google Patents

Description

Electromagnetic interference suppressor, electromagnetic interference suppression method using the same, and RF-ID device

  The present invention relates to an electromagnetic interference suppressor used for suppressing electromagnetic interference caused by interference of unnecessary electromagnetic waves in an electronic device, an electromagnetic interference suppressing method using the same, and an RF-ID device such as an IC tag and an IC card.

  In recent years, various electronic devices such as home electric appliances such as televisions, computers such as personal computers, mobile communication devices such as mobile phones, and medical devices have been widely used. Unwanted electromagnetic waves emitted from these electronic devices It adversely affects electronic devices and causes malfunctions. Therefore, in such an electronic device, an electromagnetic interference suppressor that removes unnecessary electromagnetic waves is used.

  In recent years, the electronic devices have been rapidly increased in speed, weight, thickness and size, and the mounting density of electronic components on a circuit has been dramatically increased. For this reason, along with an increase in electromagnetic noise caused by electromagnetic interference between components and circuit boards, there is a high possibility that electromagnetic interference due to unnecessary electromagnetic waves occurs between components and circuit boards in an electronic device.

  As one of the countermeasures for suppressing electromagnetic interference, Patent Document 1 discloses that a sheet-like electromagnetic interference suppressor in which soft magnetic powder is dispersed in a binder is disposed in the vicinity of an electronic component or a circuit. ing.

  Moreover, in a portable information terminal having an IC (Integrated Circuit) tag function called RF-ID (Radio Frequency Identification), a metal housing or a metal-plated housing such as metal plating is used to shield external electromagnetic waves. However, when a transmission / reception antenna arranged in the housing is close to a conductive material such as a conductive housing or a battery, magnetic field lines generated around the antenna at the time of transmission / reception are formed parallel to the metal surface of the housing. An eddy current is generated on the metal surface. Since the magnetic field generated from this eddy current is formed in a direction that cancels the electric field generated during transmission and reception, the magnetic field that can be used for communication is greatly attenuated, and the RF-ID communication distance is significantly shortened. As a method for improving this wireless communication, there is a method of disposing an electromagnetic interference suppressor between an antenna and a metal casing or a conductive material in an IC tag.

In using such an electromagnetic interference suppressor, a sheet having a high magnetic permeability is required in the region of several tens of MHz to 1 GHz. It is known that a high magnetic permeability uses a soft magnetic powder having a flat shape rather than a spherical shape, and this flat soft magnetic powder is oriented along the surface of the electromagnetic interference suppression sheet (Patent Literature). 2).
In order to facilitate orientation, it is preferable to use a material having high fluidity as the matrix material. For example, Patent Document 2 discloses a technique in which a magnetic coating material obtained by dissolving a flat soft magnetic powder and a polymer binder in an organic solvent is coated on a peelable support by a doctor blade method and dried to form a sheet. Are listed.

  However, when this processing method is used, the solvent in the magnetic paint foams during drying, which causes a problem that a large amount of pores are formed in the sheet. When a large number of holes are generated, the electromagnetic interference suppression effect is greatly reduced. Therefore, it is desirable to fill the soft magnetic powder with high density while minimizing the generation of holes.

  Further, since the specific gravity difference between the soft magnetic powder and the binder is large, there is a problem that the magnetic coating itself is easily separated into two layers. Separation into two layers is not preferable because it causes variation in product quality when applied by the doctor blade method.

Japanese Patent Laid-Open No. 7-212079 JP 2003-229694 A

An object of the present invention is to solve the problems in the conventional technology as described above, and to provide an electromagnetic interference suppressing body and an electromagnetic interference suppressing method having an excellent electromagnetic interference suppressing effect in a wide frequency range. Furthermore, the present invention provides an RF- that can reduce the influence of the proximity conductor surface and improve wireless communication in a portable information terminal having an identification function by wireless communication at 13.56 MHz called RF-ID. It is also an object to provide an ID device.
Furthermore, this invention makes it a subject to suppress that a magnetic coating material isolate | separates into two layers, and to stabilize the quality of a product.

  As a result of intensive studies to solve the above problems, the present inventors have contained a flat soft magnetic powder and a binder in a predetermined ratio, and added to a sheet body (sheet-like composition) formed therefrom. The ratio of the measured specific gravity (actual specific gravity) of the actually obtained electromagnetic interference suppressor to the specific gravity (theoretical specific gravity) calculated from the blended composition of flat soft magnetic powder, binder, etc. In the case of 0.6 or more, new knowledge that an electromagnetic interference suppressor useful for suppressing electromagnetic interference caused by interference of unwanted electromagnetic waves can be obtained by suppressing the decrease in electromagnetic interference suppression effect due to the influence of holes. The headline and the present invention were completed.

That is, the electromagnetic interference suppressor of the present invention has the following configurations (1) to (14).
(1) It contains 30 to 80% by volume of flat soft magnetic powder and 20 to 70% by volume of a binder, is subjected to pressure and crosslinking of the binder, and has an actual specific gravity / theoretical specific gravity of 0.6 or more. An electromagnetic interference suppressor.
(2) Contains 30 to 80% by volume of flat soft magnetic powder and 20 to 70% by volume of a binder, and is subjected to pressure and crosslinking of the binder, and has a surface resistivity of 10 ⁴ Ω / □ or more. An electromagnetic interference suppressor having a specific gravity of 2.8 or more.
(3) The relationship between the specific gravity A and the actual specific gravity B when substantially all of the air remaining inside the electromagnetic wave suppression body is discharged is the relationship of the formula: {(AB) / B} × 100 ≦ 40% The electromagnetic interference suppressor according to (1) or (2), wherein:
(4) The product of the actual specific gravity value d and the complex relative permeability (imaginary part) μ ″ at a specific frequency (100 MHz to 3 GHz) has a relationship of the formula: d × μ ″> 35 (1) The electromagnetic interference suppression body in any one of-(3).
(5) The product of the actual specific gravity value d and the complex relative permeability (real part) μ ′ at a specific frequency (13.56 MHz and 100 MHz to 1 GHz) is in a relationship of the formula: d × μ ′> 25 The electromagnetic interference suppressor according to any one of (1) to (4).
(6) The electromagnetic interference suppressor according to any one of (1) to (5), which is a sheet having a thickness of 1 μm to 2 mm.
(7) A magnetic paint containing flat soft magnetic powder and a binder is applied onto a support material with a blade and dried, and then a pressure of 500 kPa to 50 MPa is applied (1) to (6) The electromagnetic interference suppression body in any one of.
(8) The electromagnetic interference suppressor according to any one of (1) to (7), wherein a dielectric loss material for controlling a real part (ε ′) and an imaginary part (ε ″) of a complex relative dielectric constant is added.
(9) The dielectric loss material is at least one selected from graphite, carbon black, metal oxide, carbon fiber, and graphite fiber, and is contained in a proportion of 0 to 50% by weight based on the binder content ( The electromagnetic interference suppressor according to 8).
(10) The electromagnetic interference suppressor according to any one of (1) to (9), wherein at least one of the flat soft magnetic powder and the dielectric loss material is surface-treated.
(11) The electromagnetic interference suppressor according to (10), wherein the surface treatment is a resin coating.
(12) The electromagnetic interference suppressor according to any one of (1) to (11), wherein a dispersant is added at a ratio of 1 to 5% by weight with respect to the content of the flat soft magnetic powder.
(13) The electromagnetic interference suppressor according to (12), which contains a higher fatty acid or a higher fatty acid salt as a dispersant.
(14) The electromagnetic interference suppressor according to any one of (1) to (13), to which flame retardancy (for example, flame retardancy equivalent to UL94 V0) is imparted.
(15) The electromagnetic interference suppressor according to any one of (1) to (14), wherein an adhesive layer is provided on at least one surface.

  The electromagnetic interference suppression method of the present invention is characterized in that the electromagnetic interference suppression body is disposed in or around an electronic device.

  An electromagnetic interference suppressor according to the present invention includes an antenna and a conductor surface (enclosure) as a method for improving wireless communication in a portable information terminal having an IC (Integrated Circuit) tag function called an RF-ID (Radio Frequency Identification) device. Etc.) and is suitable for use. That is, the RF-ID device of the present invention is characterized in that the above-described electromagnetic interference suppressing body is disposed in whole or in part between the antenna and the conductor surface. Here, examples of the RF-ID device include an IC tag and an IC card.

  The electromagnetic interference suppression body of the present invention shown in the above (1) to (15) has an effect of suppressing the decrease in the electromagnetic interference suppression effect due to the influence of holes and having an excellent electromagnetic interference suppression effect. Therefore, by arranging the electromagnetic interference suppressor of the present invention inside or around the electronic device, electromagnetic interference caused by interference of unnecessary electromagnetic waves can be suppressed. In addition, the RF-ID device using the electromagnetic interference suppressor of the present invention reduces the influence of the adjacent conductor surface in the portable information terminal having an identification function by wireless communication called RF-ID, and performs wireless communication. Can be improved.

  In the electromagnetic interference suppressor according to the present invention, when a predetermined amount of dispersant is added to the content of the flat soft magnetic powder as described in (13), the magnetic paint is prevented from separating into two layers. The quality of the electromagnetic interference suppressor is stabilized.

  The electromagnetic interference suppressor of the present invention comprises a flat soft magnetic powder and a binder as main constituent materials, and may further contain a dielectric loss material, a dispersant and a flame retardant as necessary. The electromagnetic interference suppressor of the present invention is mainly used in the form of a sheet (thin magnetic sheet).

  Examples of the flat soft magnetic powder include Sendust (Fe-Si-Al alloy), Permalloy (Fe-Ni alloy), Silicon copper (Fe-Cu-Si alloy), Fe-Si alloy, Fe-Si-B (-Cu). -Nb) alloy, Fe-Ni-Cr-Si alloy, Fe-Si-Cr alloy, Fe-Si-Al-Ni-Cr alloy, Fe-Ni-Cr alloy, Fe-Cr-Al-Si alloy, etc. It is done. Further, ferrite or pure iron particles may be used. Examples of the ferrite include soft ferrite such as Mn—Zn ferrite, Ni—Zn ferrite, Mn—Mg ferrite, Mn ferrite, Cu—Zn ferrite, and Cu—Mg—Zn ferrite, or hard ferrite that is a permanent magnet material. . Examples of the pure iron particles include carbonyl iron powder. Preferably, a flat soft magnetic powder having a high magnetic permeability is used. In addition to using these magnetic materials alone, a plurality of them may be blended. As the soft magnetic powder, a combination of a flat soft magnetic powder and a non-flat soft magnetic powder (acicular, fibrous, spherical, massive, etc.) may be used, but at least one of the combinations should be flat. I need it. The particle size of the soft magnetic powder is 1 to 300 μm, preferably 20 to 100 μm. The aspect ratio of the flat soft magnetic powder is 2 to 500, preferably 10 to 100. The soft magnetic powder may have an oxide film on the surface in order to improve the corrosion resistance.

  The flat soft magnetic powder and / or dielectric loss material is preferably surface-treated. As the surface treatment, a general treatment with a coupling agent or a surfactant can be used. Among them, it is preferable to be coated with a resin. This improves the affinity between the flat soft magnetic powder and / or the dielectric loss material and the binder, so that the flat soft magnetic powder can be filled with high density. As the resin for surface coating, an organic polymer material (rubber, thermoplastic elastomer, various plastics) having the same affinity as the binder to be used or excellent affinity with the binder to be used can be used. The coating amount of the resin may be about 0.5 to 10% by weight based on the content of the coated flat soft magnetic powder and dielectric loss material.

  Various organic polymer materials can be used as the binder, and examples thereof include polymer materials such as rubber, thermoplastic elastomer, and various plastics. Examples of the rubber include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, ethylene-propylene rubber, butyl rubber, chloroprene rubber, nitrile rubber, acrylic rubber, epichlorohydrin rubber, fluorine rubber, urethane rubber, chlorine. Polyethylene rubber, hydrogenated nitrile rubber (HNBR), ethylene-vinyl acetate copolymer, ethylene-acrylic rubber, ethylene-acrylic acid ester copolymer, ethylene copolymer, synthetic rubber such as silicone rubber alone, or these These rubbers are modified by various modification treatments.

  These rubbers can be used alone or in combination. In addition to vulcanizing agents, rubbers may be appropriately mixed with vulcanization accelerators, anti-aging agents, softeners, plasticizers, fillers, coloring agents, and the like that have been conventionally used as rubber compounding agents. it can. In addition to these, arbitrary additives can be used. For example, a predetermined amount of a dielectric (carbon black, graphite, titanium oxide, etc.) for controlling the dielectric constant, and a heat conductive material (boron nitride, aluminum nitride, alumina, magnesium oxide, zinc oxide) for imparting heat dissipation characteristics Etc.) can be added by designing the material according to impedance matching to the unnecessary electromagnetic wave generated in the electronic equipment used and the temperature environment. In addition, select processing aids (such as lubricants), flame retardants (halogen flame retardants, phosphorus flame retardants, zinc flame retardants, nitrogen flame retardants, hydroxide flame retardants, antimony flame retardants) as appropriate. It may be added. These heat conductive materials and flame retardants may also be surface treated.

  Examples of the thermoplastic elastomer include various thermoplastic elastomers such as polyvinyl chloride such as chlorinated polyethylene, polystyrene, polyolefin, polyurethane, polyester, and polyamide.

  Further, as various plastics, for example, polyethylene, polypropylene, AS resin, ABS resin, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymer, fluorine resin, acrylic resin, nylon, polycarbonate And thermoplastic resins such as polyethylene terephthalate, alkyd resins, unsaturated polyesters, polysulfones, polyurethanes, phenol resins, urea resins, epoxy resins, and polyimide resins, or thermosetting resins.

  In the present invention, it is particularly preferable to use hydrogenated nitrile rubber or ethylene-vinyl acetate copolymer as the binder. When hydrogenated nitrile rubber or ethylene-vinyl acetate copolymer is used, halogen-free and heat resistance can be imparted.

  As a crosslinking agent for crosslinking the binder, for example, a peroxide, sulfur, a phenol resin compound, an isocyanate compound, a metal ion, an amine compound, a quaternary ammonium, or the like, an appropriate kind according to the kind of the binder is used. Can be used. Preferred are peroxides, such as dicumyl peroxide, t-butyl cumyl peroxide, α. α′-bis (t-butylperoxy) diisopropylbenzene and the like can be used. The addition amount of the crosslinking agent is 0.1 to 20 parts by weight, preferably 1 to 7 parts by weight with respect to 100 parts by weight of the binder. The crosslinking reaction may be achieved by, for example, light irradiation, UV irradiation, electron beam irradiation, or the like. These cross-linking agents can be applied to rubber, thermoplastic elastomers, and plastics by an appropriate combination.

  The blending ratio is preferably 30 to 80% by volume of flat soft magnetic powder and 20 to 70% by volume of binder, and more preferably 40 to 70% by volume of flat soft magnetic powder and 30 to 60% by volume of binder. . If the content of the flat soft magnetic powder is less than 30% by volume and the content of the binder exceeds 70% by volume, the desired electromagnetic interference suppression effect cannot be obtained. On the other hand, when the content of the flat soft magnetic powder exceeds 80% by volume and the content of the binder is less than 20% by volume, the obtained electromagnetic interference suppressing body becomes brittle, so that processing becomes difficult.

In order to enhance the dispersibility of the flat soft magnetic powder, it is preferable to add 1 to 5% by weight of a dispersant with respect to the content of the flat soft magnetic powder. Examples of the dispersant include, for example, a higher fatty acid and a higher fatty acid salt alone or a combination thereof. Examples of the higher fatty acid herein include stearic acid, lauric acid , and behenic acid. Examples of higher fatty acid salts include aluminum salts, sodium salts, potassium salts, lithium salts, barium salts, calcium salts, magnesium salts, and zinc salts of these higher fatty acids. The ratio of higher fatty acid / higher fatty acid salt when combined is preferably 20/80 to 80/20 by weight.

  It is important to manufacture the electromagnetic interference suppressor of the present invention so that the actual specific gravity / theoretical specific gravity is 0.6 or more. When the actual specific gravity / theoretical specific gravity is less than 0.6, since there are many pores inside the electromagnetic interference suppression body, the electromagnetic interference suppression effect is reduced. Here, the actual specific gravity is a value obtained from the weight / volume of the manufactured electromagnetic interference suppressor, and the theoretical specific gravity is the sum of the total weight of each component divided by the weight of each component. Divided by the total volume. When the electromagnetic interference suppressor is composed of a thin magnetic sheet or the like, the theoretical specific gravity value is in the range of 2.5-7.

The electromagnetic interference suppressor of the present invention preferably has an actual specific gravity of 2.8 or more, and more preferably in the range of 3 to 6. If the soft magnetic metal is highly filled to increase the specific gravity, the soft magnetic metals come into contact with each other, which may reduce the surface resistivity. When the electromagnetic interference suppression body is used, problems such as circuit coupling may occur because the electrical conductivity is obtained when the electrical resistance is too small. Although it has a high specific gravity, the surface resistivity as an electromagnetic wave interference suppressor is sufficiently high as 10 ⁴ Ω / □ or more, and it is a feature of the present invention that it has an insulation property even if not completely. . As described later, this is a mode in which the flat soft magnetic powder is not contacted as much as possible, and a binder is arranged so as to enclose each soft magnetic powder, and the flat soft magnetic metal is dispersed, oriented, and arranged in the binder. This is because.

If air remains in the interior and voids are generated, the electromagnetic interference suppressing effect is greatly reduced. Therefore, it is desirable to fill the soft magnetic powder with high density to suppress the generation of voids as much as possible. These pores (sometimes expressed as air or voids) are used when the solvent used first evaporates and the volatile matter cannot be completely removed, or when the soft magnetic powder agglomerates. This is the case when there is a gap that does not fit, or when the soft magnetic powder remains due to insufficient affinity between the binder and the flow of the binder. However, it is difficult to completely discharge the air that has once remained inside, and in fact, some residual air (air gap) will inevitably remain in the product due to the processing process and the shape and amount of the soft magnetic powder. become. This state generally means that the specific gravity is lower than the specific gravity (theoretical specific gravity) when there is essentially no air (void).

In the present invention, a specific method for increasing the specific gravity can be achieved, for example, by volatilizing a solvent from a magnetic coating material to form a sheet body, pressurizing, and further crosslinking the binder by a chemical reaction. Pressurization and cross-linking may or may not be simultaneous, but even when they are not simultaneous, it is better that they are before and after the process. The pressing method applies a pressure of 5 MPa to 25 MPa from the up and down direction of the sheet. At that time, it is more preferable to give temperature and time conditions for crosslinking simultaneously with pressurization. Thereby, the internal structure (morphology) of the sheet to which pressure is applied can be fixed by crosslinking (chemical reaction). In order to perform the flow of the binder and the crosslinking simultaneously, a crosslinking system that performs crosslinking in as short a time as possible (for example, within 5 minutes) is employed. In addition, this pressurizing method does not particularly require the use of a mold or the like, and a continuous sheet body can be obtained by a method of continuously changing the press position with the sheet body. As the crosslinking system, metal ionomerization, peroxides, isocyanates, amines and other reactants can be enclosed in pressure-sensitive and temperature-sensitive microcapsules, etc., so that arbitrary temperature, pressure, and time conditions can be selected. it can.

The reason for imparting pressure and cross-linking is that even when pressure is applied in the vertical direction of the sheet body in which a large amount of flat soft magnetic powder is filled in the binder, the flow of the binder proceeds at the time of application, and air is released. This is because the orientation of the soft magnetic powder proceeds, but immediately after the pressure is released, the sheet thickness is increased by an effect such as a springback, and it becomes the same state as when air (holes) enters. This is not only immediately after the application is removed, but there is also a phenomenon that it returns to its original state over time. Actually, even if only the pressure is applied, the sheet has a higher specific gravity immediately after pressing, but the effect expected by the offset effect Is not obtained. In order to prevent the sheet thickness recovery phenomenon immediately after the depressurization or over time, for example, there is a method of pressurizing at a temperature in the vicinity of the softening point of the binder (resin). It is to give. Since the strain due to pressurization applied to the soft magnetic powder creates a shear force sufficient to impart flow to the binder, it is also necessary to give the binder more resistance to flow. In addition, the binder itself must play a role of relaxing the residual stress while maintaining the form and the internal dispersion state. As a result, long-term performance stability can be obtained. Although the binder does not have magnetic properties, the binder is sufficiently involved in improving the magnetic properties of the electromagnetic interference suppressor of the sheet body. In particular, the density and density of the electromagnetic interference suppressor are increased. The finding that pressurization and cross-linking of the conjugate is effective for stabilization was found for the first time by the present invention.

In the present invention, the difference between the specific gravity A and the actual specific gravity B when substantially all of the air remaining inside the electromagnetic interference suppression body is discharged is expressed by the formula: {(AB) / B} × 100 }, The difference is preferably small in the range of 40% or less, more preferably 30% or less, and particularly preferably 21% or less.
As described above, the actual specific gravity of the electromagnetic interference suppressor of the product can take a value close to the theoretical specific gravity to some extent by pressurizing and crosslinking, but it is difficult to match the theoretical specific gravity. This means that air still remains inside the electromagnetic interference suppressing body. In the present invention, the specific gravity A in the case where a higher shearing force is applied to the electromagnetic interference suppression body and substantially all of the air remaining in the electromagnetic interference suppression body is exhausted and the actual electromagnetic interference suppression body are realized. From the above equation using the specific gravity B, it was found that the electromagnetic interference suppressor obtained as a product was required to achieve a high specific gravity. In other words, if the value obtained by the above formula is larger than 40%, the product itself still has a cost to be compressed, so the product has a lot of air and high specific gravity has not been achieved. Is shown. Naturally, the electromagnetic interference suppressing performance of the obtained electromagnetic interference suppressing body is poor. On the other hand, if the amount is 40% or less, the product itself has a small allowance for compression, so the product itself is already strongly compressed by the pressurization and cross-linking in the previous process, no air remains, and high specific gravity is achieved. Will be. That is, it can be determined that the electromagnetic interference suppression performance is good.

In the electromagnetic interference suppressor of the present invention, the product of the actual specific gravity value d and the complex relative permeability (imaginary part) μ ″ at a specific frequency (100 MHz to 3 GHz) is expressed by the formula: d × μ ″> 35, preferably d × μ. "> 50.
Furthermore, in the electromagnetic interference suppressor of the present invention, the product of the actual specific gravity value d and the complex relative permeability (real part) μ ′ at a specific frequency (13.56 MHz and 100 MHz to 1 GHz) is an expression: d × μ ′> 25, Preferably, d × μ ′> 35.

From the perspective of how to collect electromagnetic waves (magnetic flux) as a performance issue for electromagnetic interference suppressors, the sheet has the property of taking a high value of its complex relative permeability (real part) μ 'over a wide frequency range. Required. From the viewpoint of how to absorb (heat-convert) electromagnetic waves (magnetic flux) in the same frequency range, the sheet has the required characteristic of how high the complex relative permeability (imaginary part) μ ”is in a wide frequency range. However, this μ ″ is linked to the behavior of μ ′, and the magnitude of the degree of frequency dependence of μ ′ (behavior that μ ′ decreases as the frequency increases, see FIG. 6, for example). However, μ ”is determined as it is.

The high performance of the electromagnetic interference suppressor in the present invention refers to a noise suppression sheet having a high value of μ ′ and μ ″ in a wide frequency range (for example, 100 MHz to 1 GHz). As a means for improving communication at (13.56 MHz), it means that μ ′ at 13.56 MHz is high and μ ″ is low.

Therefore, first, consideration will be given to increasing the complex relative permeability (real part) μ ′ in a wide frequency range. The value of the complex relative permeability (real part) μ ′ is determined only by the added soft magnetic powder, and it is considered that a binder having no magnetic properties is not involved. However, according to experiments conducted by the present applicants, when the amount of the soft magnetic powder is simply increased, or when dispersion is performed with a high shear force aiming at dispersion with high filling, the complex relative permeability of the sheet ( The real part) μ ′ did not have a sufficiently high value. This is because if the soft magnetic powder is flat and layered and dispersed in multiple layers, air (voids) tends to remain between the layers, which makes it difficult to completely fill the binder. If air (void) remains, the orientation of the soft magnetic powder becomes insufficient, and even if high-performance soft magnetic powder is used, the complex relative permeability (real part) μ ′ of the sheet can be significantly reduced. all right. Conversely, when air (voids) is removed, the orientation of the soft magnetic powder can be made sufficient at the same time, and it can be said that a high complex relative permeability (real part) μ ′ is obtained. In other words, increasing the specific gravity is a measure for improving performance (higher μ ') because less air (holes, voids) remains and soft magnetic powder is oriented and arranged. I understood. In this respect, it was possible to grasp the tendency that the binder is greatly involved in addition to the soft magnetic powder.
  As for the complex relative permeability (imaginary part) μ ″, it is linked to the behavior of μ ′ as described above, but it can be controlled according to the composition and shape of the soft magnetic powder, and any low to high A value can be obtained.

  In the present invention, attention is paid to the dispersion state and the dispersion method of the soft magnetic powder, and the degree of dispersion of the magnetic paint is improved while giving a shearing force to such an extent that the shape of the soft magnetic powder is not broken. It is desirable to note that the affinity between the magnetic powder and the binder is increased and the specific gravity is increased except for air (voids). Specifically, the soft magnetic powder is controlled by controlling the flow conditions of the binder so that the filled flat soft magnetic powder can be kept densely packed in the sheet without excessive contact. Consider rheologically optimal flow conditions so that a binder skin layer can be formed on the surface or the surface layer of soft magnetic powder (for example, between molds) and carefully adopt a method of forming a dispersed state. Is desirable. Furthermore, pressurization and crosslinking were applied to the dried sheet. As a result, the flat soft magnetic powder is densely and almost non-contact oriented in the sheet, the specific gravity is increased, and the complex relative permeability (μ ′ and μ ″, especially μ ″) is improved. A suppressor is obtained.

  As described above, if the complex relative permeability (real part) μ ′ and the same (imaginary part) μ ″ of the sheet can be controlled to be high, the magnetic characteristics of the soft magnetic powder can be added to the sheet. The peak position can be shifted to an arbitrary position. For example, if the peak position of μ ″ is brought to 30 MHz to 5 GHz, it can be used as a noise suppression sheet. Further, by reducing the μ ″ value of 13.56 MHz band, 950 MHz band, and 2.4 GHz band as much as possible. It can be used as a magnetic sheet for reducing the influence of the nearby conductor surface of RF-ID wireless communication.

  The electromagnetic interference suppressor of the present invention is preferably used in the form of a thin magnetic sheet having a thickness of 1 μm to 2 mm. In general, in the case of a thin sheet, the flat soft magnetic powder aggregates inside, and there is no degree of freedom in the escape path of the volatile gas of air or solvent, and the void tends to remain in the sheet as it is. The remaining amount of air is almost lost.

  For such an electromagnetic interference suppressor of the present invention, any pressing means can be selected. For example, a magnetic paint containing flat soft magnetic powder and a binder is applied onto a support material with a blade, dried, and then subjected to rotocure, high-pressure calendering or press vulcanization.

  In the present invention, the real part (ε ′) and imaginary part (ε ″) of the complex relative permittivity can be arbitrarily controlled by adding a dielectric loss material. That is, the complex relative permeability (μ ′ and μ ″). ) Can be controlled as described above, but the complex relative dielectric constant, which is another parameter for suppressing interference, can also be arbitrarily changed.

  Such a dielectric loss material includes at least one of graphite, carbon black, metal oxide, carbon fiber, and graphite fiber in a ratio of 0 to 50% by weight with respect to the binder content. An electromagnetic interference suppressor is obtained. The complex relative permittivity can be controlled by adding a dielectric loss material, or by the type, amount, and dispersion state of the flat soft magnetic powder. As a result, the values of the real part (ε ′) and the imaginary part (ε ″) of the complex relative permittivity can be controlled while improving the complex relative permeability (μ ′ and μ ″).

  This means that, as shown in FIGS. 4 and 5, the ratio of S11 (reflected electromagnetic wave) and S21 (transmitted electromagnetic wave) of the thin sheet (electromagnetic interference suppressor) by the coaxial tube method is changed, and the electromagnetic wave reflection performance of the thin sheet It is possible to control to improve the reflection or to suppress the reflection performance. Depending on the site of use as an electromagnetic interference suppressor, it may be better to increase the degree of impedance mismatch in order to improve transmission attenuation characteristics, even though it does not require electromagnetic wave reflectivity as high as electromagnetic shielding. It is meaningful to control not only the complex relative permeability (μ ′ and μ ″) but also the real part (ε ′) and imaginary part (ε ″) values of the complex relative permittivity in order to cope with .

The meaning that the electromagnetic wave reflectivity as high as the electromagnetic wave shielding property is not necessary means that the electromagnetic interference suppressor has high insulation, and specifically, the surface resistivity (JIS-K6911) is 10 ⁴ Ω / □. Indicates that it has the above values.

  Furthermore, at least one of the flat soft magnetic powder and the dielectric loss material is preferably surface-treated. By surface-treating these, the affinity with the binder is improved, soft magnetic powder can be filled at a high density when processing the coated sheet, and the residual air can be reduced, and the specific gravity can be reduced. Can be high. For the surface treatment, use of various coupling agents such as a silane coupling agent and a titanate coupling agent, resin coating, ceramic coating, plating, and the like can be arbitrarily employed.

  When the surface treatment is performed by resin coating, the surface of the soft magnetic powder and / or the dielectric loss material is easy to perform a thin film treatment, and is suitable for serving as an insulation treatment. In addition, the effect of improving the fluidity of the above-mentioned binder is great, and even in a portion where it is difficult to obtain a sufficient flow with ordinary shearing force (for example, a portion where flat soft magnetic powders are densely overlapped and the binder cannot flow). Since the portion can be pre-coated with resin, it is useful as a means for increasing the specific gravity. At this time, in order to improve the affinity with the binder, the type of the coating resin is not particularly limited.

  In order to produce the electromagnetic interference suppressor of the present invention, a magnetic paint containing flat soft magnetic powder, a binder, a dispersant, and other compounding components is applied onto a peelable support material with a blade, dried, and then supported. After the body is peeled off, the electromagnetic interference suppressor is obtained by pressurizing with a rot cure, high pressure calendar, press vulcanization or the like. It is also possible to adopt means for orienting the flat soft magnetic powder in the in-plane direction by applying a magnetic field during or after coating the magnetic coating material on the support material.

  In preparing the magnetic coating, a solvent for dissolving or dispersing the flat soft magnetic powder and the binder is used. Such a solvent is not particularly limited, for example, ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, cyclohexanone, alcohols such as methanol, ethanol, propanol, butanol, methyl acetate, ethyl acetate, propyl acetate. , Esters such as butyl acetate, ethyl lactate and ethyl glycol acetate, ethers such as diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran and dioxane, aromatic hydrocarbon compounds such as benzene, toluene and xylene, methylene chloride, ethylene chloride, Halogenated hydrocarbon compounds such as carbon tetrachloride, chloroform and chlorobenzene can be used.

  As a dispersion and kneading apparatus for preparing the coating material, a kneader, an agitator, a ball mill, a sound mill, a roll mill, an extruder, a homogenizer, an ultrasonic disperser, a biaxial planetary kneader, or the like can be used. Of these dispersing and mixing apparatuses, an agitator, a ball mill, a roll mill, a homogenizer, an ultrasonic disperser, a two-axis planetary kneader and the like that do not break or strain the soft magnetic metal material are preferable.

  The method of applying the magnetic paint on the support is not particularly limited, and air doctor coat, blade coat, wire bar coat, air knife coat, squeeze coat, impregnation coat, reverse roll coat, transfer roll coat, gravure coat, kiss coat, Any conventional method such as cast coating, extrusion coating, die coating, and spin coating can be employed. Of these, it is particularly preferable to use the doctor blade method (blade coating).

  In pressurization by continuous vulcanization, high-pressure calendar, press vulcanization, etc., the pressure is adjusted so that the actual specific gravity / theoretical specific gravity of the obtained sheet is 0.6 or more. Roto-cure performs pressurization and cross-linking almost simultaneously, and in the case of a high-pressure calender, cross-linking is performed with a time difference before and after the process. Cross-linking can be achieved simultaneously by pressing and pressing depending on temperature and time conditions, but the time may be shifted. Also in the case of pressing, if a continuous pressurization method is adopted, a continuous sheet shape can be obtained. In this case as well, pressing and crosslinking (chemical reaction) can be performed without producing and using a mold if sandwiched between release papers. Can be obtained. Thereby, it is possible to save the cost increase such as the batch method and the mold cost. The pressurizing conditions vary depending on the type of binder, the presence / absence of heating, the heating temperature, the thickness of the electromagnetic interference suppression sheet, etc., but generally the range of 500 kPa to 50 MPa is selected. In the case of thermoforming, the temperature is desirably 250 ° C. or lower. When crosslinking is performed at the same time as or near the pressurization, the time required for them should be shortened to match the production line speed, and should be kept to 10 minutes or less, preferably within 5 minutes. is there.

As long as the actual specific gravity / theoretical specific gravity can be adjusted to 0.6 or more, or as long as the surface resistivity can be adjusted to 10 ⁴ Ω / □ or more and the actual specific gravity can be adjusted to 2.8 or more, other pressurizing means can be used. good.

Moreover, since the affinity with the binder is improved also by the resin coating on the surface of the flat soft magnetic powder, the soft magnetic powder can be filled at a high density during the coating sheet processing. In this case, the sheet obtained by coating and drying can easily have an actual specific gravity of 2.8 or more, or an actual specific gravity / theoretical specific gravity of 0.6 or more simply by applying pressure and crosslinking by applying a pressure of about 500 kPa to 50 MPa. An electromagnetic interference suppressor is obtained.
The electromagnetic interference suppressor of the present invention is generally used in the form of a sheet. The thickness of the sheet is about 1 μm to 2 mm, preferably about 10 μm to 0.5 mm.

The electromagnetic interference suppressor of the present invention is used in various electronic devices such as home electric products such as televisions, computers such as personal computers, mobile communication devices such as mobile phones, medical devices, etc., and unnecessary electromagnetic waves emitted from these electronic devices. Can suppress other electronic devices, electronic components, and circuit boards from causing malfunctions. Specifically, electromagnetic interference caused by interference of unnecessary electromagnetic waves is effectively suppressed by being disposed inside or around the electronic devices. For this reason, as a usage form of the electromagnetic interference suppression body of the present invention, for example, an adhesive layer is laminated on one surface of the electromagnetic interference suppression body, and the sheet-like electromagnetic interference suppression body is appropriately cut and pasted near the noise source of the device. Or, it may be used by forming an electromagnetic interference suppressor by applying it to the noise source or the vicinity of the device as described above.
Further, it can be used as a magnetic shield for low frequency (10 MHz or less), a radio wave absorber for GHz band wireless communication, wireless LAN, and ETC.

  Further, in a portable information terminal having an identification function by wireless communication such as an IC (Integrated Circuit) tag function called RF-ID (Radio Frequency Identification), as a method for improving the wireless communication, there is a method between an antenna and a metal housing. In addition, the electromagnetic interference suppressor according to the present invention is used.

  Hereinafter, although an electromagnetic interference suppression object of the present invention is explained in detail using an example and a comparative example, the present invention is not limited to the following examples. The materials used in the following examples and comparative examples are as follows.

-HNBR (hydrogenated acrylonitrile-butadiene rubber): Zetpol 2010H manufactured by Nippon Zeon Co., Ltd.
EVA (ethylene-vinyl acetate copolymer): EVM800SV manufactured by Bayer
・ Flat Fe-Si-Al: DT powder manufactured by Dowa Mining Co., Ltd. ・ Flat Fe-Ni-Cr-Si: JEM powder manufactured by Mitsubishi Materials Co., Ltd. ・ Stearic acid: Stearic acid lees manufactured by Nippon Oil & Fat Co., Ltd./ Stearic acid Barium: NS-B manufactured by Lead City Chemical Industry Co., Ltd.
・ Cross-linking agent: Park Mill D manufactured by Nippon Oil & Fat Co., Ltd.
Solvent: 3: 1 (weight ratio) mixture of methyl ethyl ketone (MEK) and toluene The physical properties of the used flat soft magnetic powder are shown in Table 1.

[Example 1]
<Resin coating of flat soft magnetic powder>
Surface treatment of DT-40 was performed with an epoxy-based thermosetting resin manufactured by Reginas Kasei Co., Ltd. The resin coating amount is 4% by weight with respect to the content of the flat soft magnetic powder (that is, metal powder: resin = 100: 4 in weight ratio). Further, as a post-treatment, a heat treatment was performed at 150 ° C. for 30 minutes to thermally cure the coated resin.
The resin used for the surface treatment is as shown below. The main agent and the curing agent were mixed at a ratio of 10: 1, and the surface of DT-40 was resin-coated using this.
Main agent: A-7516 (Reginas Kasei Co., Ltd.)
Curing agent: H-7610 (manufactured by Reginas Kasei Co., Ltd.)

マイクロストリップラインの伝送損失は電磁干渉抑制シート４の厚みが厚くなるほど高くなる。一般的には、厚みが薄く且つ高伝送損失の電磁干渉抑制シート４が望まれている。

表２から、実施例１の電磁干渉抑制シートは、実比重が３．００で、実比重／理論比重＝０．６８あり、また表面抵抗率は１．８×１０⁷Ω／□であり、伝送損失（吸収量）も２８．４％と大きくなっていることがわかる。 <Production of electromagnetic interference suppression sheet>
Using the flat soft magnetic powder surface-treated and the non-surface-treated flat soft magnetic powder as described above, a magnetic paint was prepared with the composition shown in Table 2, and PET (polyethylene terephthalate, release) was prepared by the doctor blade method. A sheet was formed by coating and drying on a support. Next, the peeling support was peeled off, followed by press molding (surface pressure = 15 MPa, crosslinking condition = 170 ° C. × 8 minutes) to obtain an electromagnetic interference suppression sheet having a thickness of 100 μm according to the present invention. With respect to the obtained electromagnetic interference suppression sheet, the actual specific gravity / theoretical specific gravity and 1 GHz transmission loss were measured. The results are also shown in Table 2. In the following Tables 2-7, the compounding quantity of each component is shown by the weight part. Here, in Table 2, the flat soft magnetic powder is 56% by volume, and the binder is 37% by volume.
A microstrip line with impedance Z = 50Ω was used for measurement of transmission loss. The microstrip line is a method for measuring transmission loss of nearby noise that is widely used due to its structure suitable for mounting surface-mounted components and ease of production. FIG. 1 shows the shape of the microstrip line used. In this embodiment, a linear conductor path 2 is provided on the surface of the insulator substrate 1, and an electromagnetic interference suppression sheet 4 is placed on the conductor path 2. Both ends of the conductor path 2 are connected to a network analyzer (not shown). Then, with respect to the incident wave indicated by the arrow A, the reflection amount (dB) (indicated by the arrow S11) and the transmission amount (dB) (indicated by the arrow S21) from the placement site of the electromagnetic wave absorbing material 4 are measured. The transmission loss (absorption amount) was calculated from the following equation.

The transmission loss of the microstrip line increases as the thickness of the electromagnetic interference suppression sheet 4 increases. In general, the electromagnetic interference suppression sheet 4 having a small thickness and high transmission loss is desired.

From Table 2, the electromagnetic interference suppression sheet of Example 1 has an actual specific gravity of 3.00, an actual specific gravity / theoretical specific gravity = 0.68, and a surface resistivity of 1.8 × 10 ⁷ Ω / □. It can be seen that the transmission loss (absorption amount) is also increased to 28.4%.

[Example 2 and Comparative Example 1]
<Rotocure>
A magnetic paint was prepared with the composition shown in Table 3 (unit: parts by weight), and applied to a PET (peeling support) and dried by a doctor blade method to form a sheet. Subsequently, the peeling support was peeled off, followed by rot cure (surface pressure = 700 kPa, crosslinking conditions = 170 ° C. × 8 minutes) to obtain an electromagnetic interference suppression sheet. On the other hand, for comparison, an electromagnetic interference suppression sheet of Comparative Example 1 was obtained in the same manner as above except that no rot cure was performed. About each obtained electromagnetic interference suppression sheet | seat, it carried out similarly to Example 1, and measured real specific gravity, real specific gravity / theoretical specific gravity, and 1 GHz transmission loss. The surface resistivity was 6.0 × 10 ⁸ Ω / □. The measurement results are also shown in Table 3. Here, the flat soft magnetic powder is 40% by volume, and the binder is 55% by volume. The effect of pressure and cross-linking by rotocure can be confirmed.

実施例３および４の実比重値ｄと特定周波数における複素比透磁率（虚数部）μ”との積であるｄ×μ”は４７．６（３ＧＨｚ）〜５７．３（１００ＭＨｚ）（実施例３）、３５．９（３ＧＨｚ）〜３７．４（１００ＭＨｚ）（実施例４）であり、全て３５を超している。また、ｄ×μ'は２９．５１（１ＧＨｚ）〜８７．９４（１００ＭＨｚ）（実施例３）、３９．４８（１ＧＨｚ）〜７０．５（１００ＭＨｚ）（実施例４）であり、全て２５を超している。このことから高密度と高性能を同時に達成しているといえる。
また図２および図３に、材料定数（ε’、ε”、μ’、μ”）の周波数依存性のデータを示す。図２と図３は複素比透磁率（μ’、μ”）の値は大差ないが、複素比誘電率（ε’、ε”）が大きく異なる。この違いはインピーダンスの違いに現れ、同軸管法による反射特性（Ｓ１１）および透過特性（Ｓ２１）に差が現れることになる。これについてはユーザーの使用環境に合わせ、最適な構成の電磁干渉抑制シート４を提供することができることになる。また実施例３および実施例４の表面抵抗率（ＪＩＳ−Ｋ６９１１）はそれぞれ５×１０⁸（Ω／□）、３×１０⁶（Ω／□）であり、１０⁴Ω／□以上であることを確認している。
実施例１と同様のＳ１１（反射量）およびＳ２１（透過量）測定を同軸管法において実施した。ネットワークアナライザーとしてＨＰ８７２０ＥＳ（アジレントテクノロジー社製）を用い、Ｓパラメータを測定している。この測定は、電磁波の５０ＭＨｚ〜２０ＧＨｚの範囲における反射特性（Ｓ１１）および透過特性（Ｓ２１）を求め、電磁干渉抑制シート４のインピーダンスに応じた反射および透過、そしてロス量（吸収量）が上式から求まる。実施例３および４のＳ１１結果を図４に、Ｓ２１結果を図５に示す。例えば図４より電磁波干渉シート４（実施例３）のＳ１１が、１ＧＨｚに比べ、３ＧＨｚでは約３７％向上している。これはローパスフィルター特性を示すものであり、このような挙動は用途によっては好ましい場合がある。これが、本発明において電磁干渉抑制シート４の特性として複素比透磁率（μ’およびμ”）以外に、複素比誘電率をも含めたインピーダンス特性を重視する理由でもある。 [Examples 3 and 4 and Comparative Examples 2 and 3]
<Press vulcanization>
A magnetic paint was prepared with the composition shown in Table 4 (unit: parts by weight), and was coated on a PET (peeling support) and dried by a doctor blade method to form a sheet. Subsequently, the peeling support was peeled off, followed by press molding (surface pressure = 15 MPa, cross-linking condition = 170 ° C. × 8 minutes) to obtain 100 μm-thick electromagnetic interference suppression sheets of Examples 3 and 4. On the other hand, for comparison, electromagnetic interference suppression sheets 4 of Comparative Examples 2 and 3 were obtained in the same manner as described above except that the press vulcanization was not performed. In Example 4 and Comparative Example 3, the amount of flat soft magnetic powder was adjusted and graphite was added to vary the complex dielectric constant (ε ′, ε ″). About the obtained electromagnetic interference suppression sheet 4, The actual specific gravity, actual specific gravity / theoretical specific gravity, and 1 GHz transmission loss were measured in the same manner as in Example 1. The results are also shown in Table 4. Here, Example 3 and Comparative Example 2 are flat soft magnetic powders. Is 56% by volume, and the binder is 37% by volume. In Example 4 and Comparative Example 3, the flat soft magnetic powder is 49% by volume, and the binder is 42% by volume.
Moreover, it was confirmed by the following method how the obtained electromagnetic interference suppression sheet | seat was made high specific gravity. That is , the actual specific gravity of the products of Comparative Examples 2 and 3 and Examples 3 and 4 and the specific gravity after application of shearing force (pressing with a double pressure at the time of press vulcanization) for air (void) removal shows the measured shear force application before and after the change rate. From Table 4, the specific gravity change rate {(actual specific gravity after applying shear force−actual specific gravity) / actual specific gravity} after application of the shear force of Examples 3 and 4 is smaller than that of Comparative Examples 2 and 3, and is close to the theoretical specific gravity. I understand that. That is, it can be said that Examples 3 and 4 have less air (voids) and are highly dispersed while densely covering the soft magnetic metal with the binder.

D × μ ″, which is the product of the real specific gravity value d of Examples 3 and 4 and the complex relative permeability (imaginary part) μ ″ at a specific frequency, is 47.6 (3 GHz) to 57.3 (100 MHz) (Example) 3), 35.9 (3 GHz) to 37.4 (100 MHz) (Example 4), all exceeding 35. Also, d × μ ′ is 29.51 (1 GHz) to 87.94 (100 MHz) (Example 3), 39.48 (1 GHz) to 70.5 (100 MHz) (Example 4), and all 25. It is super. From this, it can be said that high density and high performance are achieved at the same time.
2 and 3 show data on the frequency dependence of the material constants (ε ′, ε ″, μ ′, μ ″). FIG. 2 and FIG. 3 do not differ greatly in the value of the complex relative permeability (μ ′, μ ″), but the complex relative permittivity (ε ′, ε ″) differs greatly. This difference appears in the difference in impedance, and a difference appears in the reflection characteristic (S11) and transmission characteristic (S21) by the coaxial tube method. In this regard, the electromagnetic interference suppression sheet 4 having an optimal configuration can be provided in accordance with the user's usage environment. Further, the surface resistivity (JIS-K6911) of Example 3 and Example 4 is 5 × 10 ⁸ (Ω / □) and 3 × 10 ⁶ (Ω / □), respectively, and is 10 ⁴ Ω / □ or more. Have confirmed.
The same S11 (reflection amount) and S21 (transmission amount) measurement as in Example 1 was performed in the coaxial tube method. HP8720ES (manufactured by Agilent Technologies) is used as a network analyzer, and S parameters are measured. In this measurement, the reflection characteristic (S11) and transmission characteristic (S21) of the electromagnetic wave in the range of 50 MHz to 20 GHz are obtained, and the reflection and transmission according to the impedance of the electromagnetic interference suppression sheet 4 and the loss amount (absorption amount) are the above formulas. Obtained from The S11 results of Examples 3 and 4 are shown in FIG. 4, and the S21 results are shown in FIG. For example, FIG. 4 shows that S11 of the electromagnetic wave interference sheet 4 (Example 3) is improved by about 37% at 3 GHz as compared with 1 GHz. This shows a low-pass filter characteristic, and such behavior may be preferable depending on the application. This is also the reason why importance is placed on the impedance characteristics including the complex relative permittivity in addition to the complex relative permeability (μ ′ and μ ″) as the characteristics of the electromagnetic interference suppressing sheet 4 in the present invention.

表５から、分散剤としてステアリン酸とステアリン酸塩を加えた実施例５の組成は、分散安定性に優れていることがわかる。 [Example 5, Comparative Example 4]
<Effect of dispersant>
Each component was mixed with the composition shown in Table 5 (unit: parts by weight) to prepare a magnetic coating material, which was allowed to stand and the sedimentation state of the soft magnetic powder was visually observed. The results are also shown in Table 5. Here, the flat soft magnetic powder is 40% by volume, and the binder is 55% by volume.

From Table 5, it can be seen that the composition of Example 5 in which stearic acid and stearate were added as dispersants was excellent in dispersion stability.

実施例６での実比重値ｄと特定周波数における複素比透磁率（実数部）μ'との積であるｄ×μ'は１６５．５（１３．５６ＭＨｚ）であり、３５を超している。このことから高密度と高性能を同時に達成しているといえる。また表面抵抗率は１．８×１０⁸Ω／□であった。
また、表６から、ＵＬ９４規格のＶ０相当の難燃性を有しながら、伝送損失（１ＧＨｚ）は高く、電磁干渉抑制シート４として優れた特性を持つことがわかる。 [Example 6]
A magnetic paint was prepared with the composition shown in Table 6 (unit: parts by weight), and was coated on a PET (peeling support) and dried by a doctor blade method to form a sheet. Subsequently, the peeling support was peeled off, followed by press molding (surface pressure = 15 MPa, crosslinking condition = 170 ° C. × 8 minutes) to obtain electromagnetic interference suppression sheets having a thickness of 100 μm and 150 μm. With respect to the obtained electromagnetic interference suppression sheet 4, the actual specific gravity / theoretical specific gravity and 1 GHz transmission loss were measured in the same manner as in Example 1. Further, a flame retardant test was performed based on the UL94 standard. The results are also shown in Table 6. Here, the flat soft magnetic powder is 40% by volume, and the binder is 43% by volume. Moreover, the material constant of the sheet | seat obtained in Example 6 is shown in FIG.

D × μ ′, which is the product of the actual specific gravity value d in Example 6 and the complex relative permeability (real part) μ ′ at a specific frequency, is 165.5 (13.56 MHz) and exceeds 35. . From this, it can be said that high density and high performance are achieved at the same time. The surface resistivity was 1.8 × 10 ⁸ Ω / □.
Further, from Table 6, it can be seen that the transmission loss (1 GHz) is high and has excellent characteristics as the electromagnetic interference suppression sheet 4 while having flame resistance equivalent to V0 of UL94 standard.

表７から、電磁干渉抑制体１１を使用しない場合は通信不能であったのに対し、ＩＣタグ１０と金属板１２の間に電磁干渉抑制体１１（１５０μｍ厚）を配置することで、ＩＣタグ１０とリーダ・ライタ１３を５３ｍｍ離しても通信できるようになったことが分かる。 [Test example]
<Measurement of communication distance using RFID system FeliCa reader / writer evaluation kit (13.56 MHz)>
The communication distance between the IC tag and the reader / writer was measured using a FeliCa reader / writer evaluation kit RC-S440C manufactured by Sony Corporation. As shown in FIG. 7 , the measurement method is such that the electromagnetic interference suppressor 11 and the metal plate 12 (iron plate) are arranged on the back surface of the IC tag 10, and the communication distance L between the IC tag and the reader / writer is measured in this state. . Table 7 shows the measurement results. Two types of electromagnetic interference suppressors 11 having a thickness of 100 μm and 150 μm were used. In general, the communication distance L is about 10 cm in a free space without the metal plate 12, but when the metal plate 12 is installed close to the tag 10, the communication distance becomes 0 cm.

From Table 7, it was impossible to communicate when the electromagnetic interference suppression body 11 was not used, but by placing the electromagnetic interference suppression body 11 (150 μm thick) between the IC tag 10 and the metal plate 12, the IC tag It can be seen that communication is possible even if the distance between the 10 and the reader / writer 13 is 53 mm away.

  FIG. 8 shows the relationship between the actual specific gravity of the sheets obtained in Examples 1 to 6 and Comparative Examples 1 to 3 and the transmission loss (absorption rate) at 1 GHz. Compared with the comparative example, each example has an actual specific gravity of 2.8 or more, a transmission loss value is increased, and high performance is achieved. When the filling amount of the soft magnetic metal and the flame retardant increases, the theoretical specific gravity value increases, but an increase in the actual specific gravity of the electromagnetic interference suppression sheet 4 cannot be easily achieved. In the present invention, by introducing pressure or crosslinking, a high actual specific gravity value can be obtained while keeping the surface resistivity high, and as a result, high performance can be achieved.

It is the schematic which shows the shape of the microstrip line used for the measurement of the transmission loss in an Example. 6 is a graph showing material constants of a sheet obtained in Example 3. 6 is a graph showing material constants of a sheet obtained in Example 4. It is a graph which shows the change of S11 measured with the coaxial pipe | tube (S parameter method) of the sheet | seat obtained in Example 3 and Example 4. FIG. It is a graph which shows the change of S21 measured with the coaxial pipe | tube (S parameter method) of the sheet | seat obtained in Example 3 and Example 4. FIG. 6 is a graph showing material constants of a sheet obtained in Example 6. FIG. It is the schematic which shows the measuring method of the communication distance by RFID system FeliCa reader / writer evaluation kit. It is a graph which shows the relationship between the actual specific gravity of the obtained sheet | seat, and the transmission loss in 1 GHz.

Explanation of symbols

4: Electromagnetic interference suppression sheet, 11: Electromagnetic interference suppression body