JP2006128649A - Electromagnetic compatibility suppressor and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic compatibility suppressor, having superior electromagnetic compatibility suppressing effect, and to provide a method of easily and efficiently manufacturing the electromagnetic compatibility suppressor by using flat soft magnetic powder. <P>SOLUTION: The electromagnetic compatibility suppressor is manufactured by applying magnetic paint 3 containing the flat soft magnetic powder and a binder on a support 5, and drying the magnetic paint 3 thereon. The magnetic pain 3 is applied onto the support 5 by a roll 2, which is made to rotate in the direction opposite to that of the traveling support 5 or in the same direction as the support 5 with a different circumferential velocity from the support 5. In the electromagnetic compatibility suppressor, obtained by this method, (1) an actual specific gravity/theoretical specific gravity ratio is 0.6 or higher, and (2) specific gravity A and actual specific gravity B satisfy, when air remaining in the suppressor is substantially discharged, the relation of the equation:ä(A-B)/B}×100≤40%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  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 and a method for manufacturing the same.

  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. As this electromagnetic interference suppressor, Patent Document 1 describes a sheet-like electromagnetic interference suppressor in which soft magnetic powder is dispersed in a binder.

  In general, the electromagnetic interference suppressor is often used in the form of a sheet in the region of several tens of MHz to several GHz, and high magnetic permeability is required. It is known that a high magnetic permeability can be obtained by using a soft magnetic powder having a flat shape rather than a spherical shape and orienting the flat soft magnetic powder along the surface of the electromagnetic interference suppression sheet. (Patent Document 2).

  As a method for producing such an electromagnetic interference suppressor, Patent Document 2 discloses that a magnetic coating material obtained by dissolving a flat soft magnetic powder and a polymer binder in an organic solvent is applied onto a peelable support by a doctor blade method. A method of coating and drying to form a sheet is described. However, this method requires a step of applying a magnetic field to orient the flat soft magnetic powder.

  On the other hand, Patent Document 3 states that an electromagnetic wave absorbing layer formed by applying and drying a magnetic coating material obtained by dissolving a soft magnetic powder and a binder in an organic solvent on a peelable support with a knife coater is laminated. A manufacturing method of a featured electromagnetic wave absorber (electromagnetic interference suppressor) is described. However, since the shape of the soft magnetic powder used in Patent Document 3 is not flat, there is no need for orientation and there is no concept of orientation.

Japanese Patent Laid-Open No. 7-212079 JP 2003-229694 A JP 2000-101283 A

  The present invention solves the problems of the prior art as described above, and uses flat soft magnetic powder to easily and efficiently manufacture an electromagnetic interference suppressor having an excellent electromagnetic interference suppression effect, and the electromagnetic interference suppressor. It is an object of the present invention to provide a method for performing the above.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have been driven to rotate in a direction opposite to the direction in which the support travels or in the same direction and at a peripheral speed different from the travel speed of the support. When a magnetic coating is applied on the support by a roll, the flat soft magnetic powder contained in the magnetic coating can be oriented along the surface of the electromagnetic interference suppressor at the same time as the application, and the density can be easily increased. Therefore, the inventors have found a new finding that an electromagnetic interference suppressor useful for suppressing electromagnetic interference caused by interference of unnecessary electromagnetic waves can be produced with high efficiency, and have completed the present invention.

That is, the densified electromagnetic interference suppressor according to the present invention has the following configuration.
(1) An electromagnetic interference suppressor containing 30 to 80% by volume of flat soft magnetic powder and 20 to 70% by volume of a binder and having an actual specific gravity / theoretical specific gravity of 0.6 or more.
(2) The specific gravity A and the actual specific gravity B when 30% to 80% by volume of the flat soft magnetic powder and 20% to 70% by volume of the binder are discharged, and the actual specific gravity B : The electromagnetic interference suppressor according to (1), which satisfies a relationship of {(AB) / B} × 100 ≦ 40%.
(3) The electromagnetic interference suppressor according to (1) or (2), wherein the binder is rubber.
(4) In the measurement of transmission loss using a microstrip line with impedance Z = 50Ω, when the thickness of the electromagnetic interference suppressor is 60 μm, the transmission loss (absorption rate) at 1 GHz is 10% or more, and the transmission at 2 GHz. The electromagnetic interference suppressor according to any one of (1) to (3), wherein the loss (absorption rate) is 20% or more.
(5) The electromagnetic interference suppressor according to any one of (1) to (4), wherein the flat soft magnetic powder has an average particle diameter of 5 to 100 μm and an aspect ratio of 5 to 100.
Moreover, the method of manufacturing the said electromagnetic interference suppression body consists of the following structures.
(6) A method of producing an electromagnetic interference suppressor by applying a magnetic coating containing a flat soft magnetic powder and a binder onto a support and drying the coating.
The magnetic coating material is applied onto the support by a roll that is rotationally driven in a direction opposite to the direction in which the support travels or in the same direction and at a peripheral speed different from the travel speed of the support. A method of manufacturing an electromagnetic interference suppressor.
(7) The method for producing an electromagnetic interference suppressor according to (6), wherein the magnetic paint is applied onto a support using a gravure coater.
(8) The method for producing an electromagnetic interference suppressor according to (6), wherein the magnetic paint is applied onto a support using a reverse roll coater.
(9) A method for manufacturing an electromagnetic interference suppressor in which two or more electromagnetic interference suppressors obtained by the manufacturing method according to any one of (6) to (8) are stacked.
(10) A method for producing an electromagnetic interference suppressor, wherein the electromagnetic interference suppressor obtained by the production method according to any one of (6) to (9) is subjected to rot cure, high-pressure calender, or press vulcanization.

Since the electromagnetic interference suppressor of the present invention is densified, there is an effect that an electromagnetic interference suppressor useful for suppressing electromagnetic interference caused by interference of unnecessary electromagnetic waves can be obtained simply and efficiently. Moreover, the fall of the electromagnetic interference suppression effect by the influence of a void | hole is suppressed, and it has the outstanding electromagnetic interference suppression effect.
According to the method for manufacturing an electromagnetic interference suppressor of the present invention, the flat soft magnetic powder contained in the magnetic paint can be oriented along the surface of the electromagnetic interference suppressor at the same time as the application, and the electromagnetic interference suppressor can be easily obtained. The density can be increased.

  Hereinafter, an electromagnetic interference suppressor and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings. The electromagnetic interference suppressor according to the present invention is manufactured by applying a magnetic paint containing a flat soft magnetic powder and a binder onto a support and drying it.

  Examples of the flat soft magnetic powder include magnetic stainless steel (Fe—Cr—Al—Si alloy), sendust (Fe—Si—Al alloy), permalloy (Fe—Ni alloy), and 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 and the like. 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. The average particle size of the soft magnetic powder is preferably 5 to 100 μm. In the present invention, a flat soft magnetic powder is used. However, the flat shape may be artificially created or may be formed by a pulverization process. It is not necessary for all powders to have a flat shape, and the flat soft magnetic powder referred to in the present invention also includes a case where the powder has a partial or flat shape. The aspect ratio of the flat soft magnetic powder is preferably 5 to 100.

  The surface of the flat soft magnetic powder is preferably resin-coated, and this improves the affinity with 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 is preferably about 0.5 to 10% by volume with respect to the coated flat soft magnetic powder. In place of the resin coating, use of a coupling agent, ceramic coating, plating, or the like may be performed.

  As the binder, various organic polymer materials can be used, 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. Synthetic rubbers such as hydrogenated polyethylene rubber and hydrogenated nitrile rubber (HNBR) alone, or those obtained by modifying these rubbers 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 dielectric material (carbon black, graphite, titanium oxide, etc.) for controlling the dielectric constant, and heat conductive material for imparting heat dissipation properties (boron nitride, aluminum hydroxide, aluminum nitride, alumina, etc.) Can be added by designing the material according to impedance matching to an unnecessary electromagnetic wave generated in the electronic equipment to be used and the temperature environment. Furthermore, processing aids (such as lubricants), flame retardants (halogen flame retardants, phosphorus flame retardants, zinc flame retardants, nitrogen flame retardants, hydroxide flame retardants) may be appropriately selected and added. .

  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 resin, unsaturated polyester, polysulfone, polyurethane, phenol resin, urea resin, and epoxy resin, or thermosetting resins.

  Particularly in the present invention, it is particularly preferable to use hydrogenated nitrile rubber, ethylene-vinyl acetate copolymer or chlorinated polyethylene as the binder. When hydrogenated nitrile rubber and ethylene-vinyl acetate copolymer are used, halogen-free and heat resistance can be imparted, and when chlorinated polyethylene is used, processability is improved.

  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 improve the dispersibility of the flat soft magnetic powder, 1 to 5% by weight of a dispersant may be added to the content of the flat soft magnetic powder. Examples of the dispersant include a combination of a higher fatty acid and a higher fatty acid salt. Examples of the higher fatty acid herein include stearic acid, lauric acid, maleic acid, behenic acid and the like. Examples of higher fatty acid salts include aluminum salts, sodium salts, potassium salts, lithium salts, barium salts, calcium salts, and magnesium salts of these higher fatty acids. The higher fatty acid and the higher fatty acid salt can be used alone or in combination. The ratio when the higher fatty acid / higher fatty acid salt is combined is preferably 20/80 to 80/20 by weight.

  In preparing the magnetic paint, 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 (MIBK), cyclohexanone, alcohols such as methanol, ethanol, propanol, butanol, methyl acetate, ethyl acetate , Esters such as propyl acetate, 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, Halogenated hydrocarbon compounds such as ethylene chloride, 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. Among these dispersing and mixing apparatuses, an agitator, a ball mill, an ultrasonic disperser, a two-axis planetary kneader, etc. that do not break or strain the soft magnetic metal material are preferable.

  The support is not particularly limited, and examples thereof include paper, paper laminated with a polymer resin such as polyolefin, polymer resin, cloth, nonwoven fabric, and metal. Of these, a thin and strong polymer resin is preferable, and examples of the polymer resin include polyesters such as polyethylene phthalate, polyethylene-2, 6-naphthalate, polyolefins such as polyethylene and polypropylene, and polyolefins such as these. Fluorine resin in which part or all of hydrogen is replaced with fluorine resin, cellulose derivatives such as cellulose triacetate and cellulose diacetate, vinyl resins such as polyvinyl chloride, vinylidene resins such as polyvinylidene chloride, polycarbonate, polyphenylene sulfide, polyamideimide And polyimide. The surface of these polymer resins is preferably peeled with a release agent such as a silicone resin because the electromagnetic interference suppressor can be easily peeled off. These polymer resins are preferably in the form of a film having a thickness of about 6 μm to 188 mm.

  Examples of means for applying the magnetic paint on the support include those shown in FIGS. FIG. 1 is a schematic explanatory view showing a method of applying a magnetic paint in the present invention. As shown in FIG. 1, a magnetic paint 3 prepared by dissolving the flat soft magnetic powder and a binder in the solvent is set in a pan 4 (paint tank). Further, the coating roll 2 is disposed in a state where a part of the coating roll 2 is immersed in the coating material 3, and is set to be driven to rotate in the direction opposite to the traveling direction of the support 5. Further, the measuring roll 8 is arranged in the vicinity of the coating roll 2 with a certain distance from the coating roll 2, and is set to rotate in the direction opposite to the rotation direction of the coating roll 2. The coating amount of the paint 3 can be adjusted by changing the distance between the measuring roll 8 and the coating roll 2 or the peripheral speed of these rolls. In this state, the support 5 supported by the backup roll 6 travels in the direction of the arrow, and a predetermined amount of magnetic paint is applied to one side of the support 5 by the application roll 2 that is driven to rotate in the direction opposite to the travel direction. 3 is applied.

  Simultaneously with this application, the flat soft magnetic powder contained in the paint 3 is oriented in the in-plane direction of the electromagnetic interference suppressor. This is presumed to be due to a shearing force generated between the coating material 3 and the support 5 during application. This shearing force can be determined by the difference between the running speed of the support 5 and the peripheral speed of the coating roll 2, the gap between the support 5 and the coating roll 2, the viscosity of the coating 3, and the like. The difference between the running speed of the support 5 and the peripheral speed of the coating roll 2 is such that the shape of the flat soft magnetic powder is not broken by the shearing force generated during coating, and the flat soft magnetic powder is in the in-plane direction. It is sufficient that the difference is the degree of orientation, and specifically, 0.5 to 20 m / min is preferable. The viscosity of the paint 3 is preferably 1000 to 50,000 mPa · s in view of workability, although the higher the viscosity, the higher the shearing force.

  Thereby, the obtained electromagnetic interference suppressor can have an actual specific gravity / theoretical specific gravity of 0.6 or more. If the actual specific gravity / theoretical specific gravity is less than 0.6, a large amount of pores are present inside the electromagnetic interference suppressing body, and the electromagnetic interference suppressing effect is reduced. Here, the actual specific gravity is a value obtained from the weight / volume of the produced electromagnetic interference suppressor, and the theoretical specific gravity is obtained by dividing the sum of specific gravity × content of each component by 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 2.5-5.

  In the present invention, when the difference between the specific gravity A and the actual specific gravity B when substantially all of the air remaining inside is discharged is represented by the formula: {(AB) / B} × 100} × 100, This difference is preferably small in the range of 40% or less, and more preferably 30% or less, particularly 21% or less. Specifically, in the present invention, a thin magnetic sheet (suppressing electromagnetic interference) is provided in a state where air (air gap) is sufficiently removed, that is, a product having a high specific gravity (a state close to the theoretical specific gravity). Body) The difference between the specific gravity of the product and the specific gravity when the shear force is applied to discharge the air in the sheet is 40% or less, preferably 21% or less compared to the specific gravity before the shear force is applied. It can be.

  In the electromagnetic interference suppressor of the present invention, the support 5 coated with the magnetic paint 3 is passed through a drying furnace (not shown), the applied paint 3 is dried, and then the support 5 is peeled off. Can be obtained. This electromagnetic interference suppressor is preferably used in the form of a thin magnetic sheet having a thickness of 10 to 500 μm. Even in the case of laminating two or more layers, the film thickness of the obtained sheet may be in the above range. 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.

When the thickness of the electromagnetic interference suppressor of the present invention is 60 μm, the transmission loss (absorption rate) of 1 GHz is 10% or more in the measurement of the transmission loss using the microstrip line with the impedance Z = 50Ω, and the 2 GHz The transmission loss (absorption rate) is preferably 20% or more. The specific measurement method is as described in the examples. The electromagnetic interference suppressor of the present invention is characterized in that the transmission loss (absorption rate) is higher than that of the conventional electromagnetic interference suppressor.
Transmission loss (absorption rate) varies with thickness, but the variation is linearly proportional to thickness to some extent. Therefore, even if the thickness is other than 60 μm, the transmission loss (absorption rate) at the thickness can be predicted.

  FIG. 2 is a schematic explanatory view showing another coating method in the present invention. As shown in FIG. 2, the coating roll 12 has a circumferential speed different from the traveling speed of the support 15 in the same direction as the traveling direction of the support 15, that is, the circumferential speed of the coating roll 12 is higher than the traveling speed of the support 15. It is set to rotate slowly or fast. Also by this coating method, the flat soft magnetic powder contained in the magnetic paint 13 is oriented in the in-plane direction at the same time as the coating as in the above coating method. Since the configuration other than the above is the same as the application method described above, the same reference numerals as those in FIG.

  In the manufacturing method of the electromagnetic interference suppression body concerning this invention, it is preferable that it is a gravure coater using the gravure roll which engraved the gravure pattern in the perimeter of the roll. According to this coater, in addition to the effects obtained by the coating method described above, the amount of coating applied to the support can be accurately controlled. Specifically, it can be controlled by the type and depth of the gravure pattern of the gravure roll, the angle and position of the blade described later.

  Examples of the gravure pattern (engraved shape) include those having concave portions such as a triangle, a quadrangle, and a spiral. The coating amount of the paint can be adjusted by the depth of the gravure pattern, and this depth is preferably 50 to 1000 μm. The blade is preferably one that can scrape off excess paint that has entered the recess of the gravure pattern while moving left and right. The gravure roll is preferably plated in terms of durability.

  The gravure coater using this gravure roll may be an offset gravure coater. According to this coater, since a shearing force is applied to the coating material when it is transferred from the gravure roll to the coating roll and when it is transferred from the coating roll to the support, the flat soft magnetic powder contained in the coating material is applied. Orientation in the in-plane direction is likely to occur. Moreover, a coating material can also be uniformly apply | coated to a support body. Hereinafter, it will be described in detail with reference to the drawings.

  FIG. 3 is a schematic explanatory view showing an example of this coater. The offset gravure coater 21 includes a gravure roll 28, a coating roll 22 and a backup roll 26 from the bottom. A vibrating blade 27 is disposed in the vicinity of the gravure roll 28, and a part thereof is immersed in the magnetic paint 23 set on the pan 24. The coating roll 22 is set so as to be rotationally driven in the direction opposite to the traveling direction of the support 25.

  In this state, the support 25 supported by the backup roll 26 travels in the direction of the arrow, and the paint 23 is driven to rotate in the direction opposite to the travel direction of the support 25 from the gravure roll 28 that rotates in the direction of the arrow. It is applied to one side of the support 25 after being transferred to the application roll 22. Thereby, the coating material 23 is uniformly applied to the support 25 and the flat soft magnetic powder contained in the coating material 23 is oriented in the in-plane direction. The excess paint 23 that has entered the concave portion of the gravure pattern of the gravure roll 28 is scraped off by the vibration blade 27 before being transferred to the application roll 22.

Further, the rotation directions of the gravure roll 28 and the coating roll 22 are opposite to those described above, and the coating roll 22 is set to rotate at the same speed as the traveling direction of the support 25 and at a peripheral speed different from the traveling speed of the support 25. May be. Even in this case, the same effect as described above can be obtained.
In addition, since structures other than those described above are the same as the application method described above, description thereof is omitted.

  In the method for manufacturing an electromagnetic interference suppressor according to the present invention, the coater to be used may be a reverse roll coater. When this coater is used, a paint having a wide viscosity range from low viscosity to high viscosity (for example, 50,000 cps) can be applied, and the film thickness can be easily controlled. There are various types of coaters depending on how the rolls are arranged. Hereinafter, it will be described in detail with reference to the drawings.

  FIG. 4 is a schematic explanatory view showing an example of this coater. The reverse roll coater 31 includes a backup roll 36, a coating roll 32, and a metering roll 38 and three rolls from the bottom, and the metering roll 38 is disposed with a certain distance from the coating roll 32, and the coating roll The flexible blade 40 is disposed in the vicinity thereof so as to be driven to rotate in a direction opposite to the direction 32. The coating roll 32 is set so as to rotate in the direction opposite to the traveling direction of the support 35. A cleaning blade 37, a scraping can 39 and a paint weir 34 are disposed in the vicinity of the application roll 32. The magnetic paint 33 is set in an internal space partitioned by a metering roll 38, an application roll 32 and a paint weir 34. The coating amount of the paint 33 can be adjusted by the interval between the coating roll 32 and the metering roll 38 that rotate in the direction of the arrow, and can also be adjusted by changing the peripheral speed of these rolls. .

  In this state, the support 35 supported by the backup roll 36 travels in the direction of the arrow, and the coating material 33 supplied from the predetermined interval and peripheral speed of the application roll 32 and the metering roll 38 is applied to the support 35. It is applied to one side of the support 35 by an application roll 32 that is rotationally driven in the direction opposite to the traveling direction. Thereby, the coating material 33 is applied to the support 35 with a predetermined film thickness, and the flat soft magnetic powder contained in the coating material 33 is oriented in the in-plane direction.

The paint 33 adhering to the metering roll 38 is scraped off by the flexible blade 40. Further, the coating material 33 not applied and adhered to the application roll 32 is scraped off by the cleaning blade 37. Since the paint 33 thus scraped off falls on the scraper can 39, the periphery of the coater 31 is not soiled.
Since the configuration other than the above is the same as the above-described coating method, the description thereof is omitted.

  FIG. 5 is a schematic explanatory view showing another example of the reverse roll coater in the present invention. The reverse roll coater 41 is composed of four rolls, a pumping roll 49, a coating roll 42, a metering roll 48, and a backup roll 46 from below. Further, the magnetic paint 43 is set on the pan 44, the pumping roll 49 is disposed in a state of being partially immersed in the paint 43, and the coating roll 42 is set so as to be driven to rotate in the direction opposite to the traveling direction of the support 45. Yes.

According to the reverse roll coater 41, the film thickness can be controlled more accurately than in the case of the three rolls described above, and the magnetic coating material 43 is transferred from the pumping roll 49 to the coating roll 42. Since the shearing force is applied when the coating roll 42 is transferred to the support 45, the orientation of the flat soft magnetic powder contained in the coating 43 in the in-plane direction is likely to occur.
In addition, since structures other than those described above are the same as those of the application method and the reverse roll coater described above, description thereof is omitted.

  In the method for manufacturing an electromagnetic interference suppressor according to the present invention, the coater to be used may be a comma coater. FIG. 6 is a schematic explanatory view showing an example of this coater. The comma coater 61 (comma direct) includes a backup roll 66 and a comma roll 68 fixed to the backup roll 66 at a fixed interval. A paint weir 64 is provided in the vicinity of the backup roll 66. The magnetic paint 63 is set in an internal space partitioned by a comma roll 68, a backup roll 66 and a paint weir 64. The coating amount of the paint 63 can be adjusted by, for example, an interval between the backup roll 66 and the comma roll 68.

In this state, the support body 65 supported by the backup roll 66 travels in the direction of the arrow, and the comma 63 with the coating material 63 adjusted to a predetermined interval has a predetermined film thickness on one surface of the support body 65. Applied. Also by this coating method, the flat soft magnetic powder contained in the magnetic paint 63 is oriented in the in-plane direction simultaneously with the coating, as in the above-described coating method.
In addition, since structures other than those described above are the same as the application method described above, description thereof is omitted.

  FIG. 7 is a schematic explanatory view showing another example of the comma coater in the present invention. The comma coater 71 (comma reverse) includes an application roll 72, a comma roll 78, and a backup roll 76. The application roll 72 is provided with a paint weir 74 in the vicinity thereof, and rotates in a direction opposite to the traveling direction of the support body 75. It is set to drive. Further, the comma roll 78 is fixed to the coating roll 72 with a certain interval. The magnetic paint 73 is set in an internal space partitioned by a comma roll 78, an application roll 72 and a paint weir 74.

According to this coater 71, as compared with the case of the coater 61 described above, the magnetic paint 73 is subjected to a shearing force when transferred from the coating roll 72 to the support 75, so that the flatness contained in the paint 73 is reduced. Orientation in the in-plane direction of the soft magnetic powder tends to occur.
In addition, since structures other than those described above are the same as those of the application method and the comma coater described above, description thereof is omitted.

  The electromagnetic interference suppressor of the present invention may be laminated in two or more layers. According to this, the electromagnetic interference suppressing body can be further densified. It does not specifically limit as a method of laminating | stacking, It can laminate | stack by various well-known methods. For example, a method using an adhesive or a pressure-sensitive adhesive, a pressure bonding method, a heat pressure bonding method, or the like can be given. If adhesion cannot be achieved only by thermocompression bonding, it is more tight to apply an appropriate solvent to the surface of the electromagnetic interference suppressor to be crimped, and to heat-compress with the surface of the electromagnetic interference suppressor dissolved. It is preferable in that pressure bonding is possible.

  If necessary, the obtained electromagnetic interference suppressor may be rot-cured, high-pressure calender or press vulcanized. According to this, the density of the obtained electromagnetic interference suppressing body can be further increased. This is particularly effective when the electromagnetic interference suppressor is thick. The pressurizing condition varies 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 10 kPa to 50 MPa is selected. In the case of thermoforming, the temperature is desirably 250 ° C. or lower.

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 suppressor of the present invention, for example, a sheet-like electromagnetic interference suppressor is appropriately cut out and pasted near the noise source of the device, or as described above near the noise source of the device. It is used, for example, by forming an electromagnetic interference suppressor by coating.
Furthermore, as a low frequency (10 MHz or less) compatible magnetic shield, GHz band wireless communication, wireless LAN, flame retardant combination of ETC radio wave absorbers, and antenna communication improvement sheets for metal and liquid countermeasures in RFID Can be used.

  EXAMPLES Hereinafter, although an electromagnetic interference suppression body and its manufacturing method of this invention are demonstrated in detail, giving an Example and a comparative example, this invention is not limited to a following example. The materials used in the following examples and comparative examples are as follows.

H-NBR (hydrogenated acrylonitrile-butadiene rubber): Zetpol 2010H manufactured by Nippon Zeon Co., Ltd.
・ Flat soft magnetic powder: JEM powder manufactured by Mitsubishi Materials ・ Stearic acid: Stearic acid cocoon manufactured by Nippon Oil & Fats ・ Barium stearate: NS-B manufactured by Lead City Chemical Industry
・ Cross-linking agent: Park Mill D made by NOF
Solvent: 3: 1 (weight ratio) mixture of methyl isobutyl ketone (MIBK) and toluene The physical properties of the flat soft magnetic powder used are as shown in Table 1.

<Production of electromagnetic interference suppression sheet>
A magnetic paint was prepared with the composition shown in Table 2, and the reverse roll coater (running speed of the support 35: 2 m / min, peripheral speed of the coating roll 32: 1 m / min, coating liquid viscosity: 4000 mPa · In s), it was coated on a polyethylene terephthalate (PET) film and dried to form a sheet. Subsequently, the PET film was peeled off to obtain an electromagnetic interference suppression sheet having a thickness of 60 μm. About the obtained electromagnetic interference suppression sheet | seat, transmission loss of real specific gravity / theoretical specific gravity, 1 GHz, and 2 GHz was measured. The results are shown in Table 3.

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５４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５４が望まれている。 <Measurement method of transmission loss>
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. 8 shows the shape of the microstrip line used. In this device, a linear conductor path 52 is provided on the surface of an insulating substrate 51, and an electromagnetic interference suppression sheet 54 is stuck on the conductor path 52 with a double-sided tape (not shown) having a thickness of 30 μm. . Both ends of the conductor path 52 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 54 are measured. The transmission loss (absorption rate) was determined from the following equation using the difference between the two as the loss amount.

The transmission loss of the microstrip line increases as the thickness of the electromagnetic interference suppression sheet 54 increases. In general, an electromagnetic interference suppression sheet 54 having a small thickness and high transmission loss is desired.

  The electromagnetic interference suppression sheet was applied in the same manner as in Example 1 except that an electromagnetic interference suppression sheet having a thickness of 80 μm obtained by applying and drying with a reverse roll coater was press-molded (surface pressure = 5 MPa) to a thickness of 60 μm. Got. With respect to the obtained electromagnetic interference suppression sheet, in the same manner as in Example 1, transmission loss at actual specific gravity / theoretical specific gravity, 1 GHz and 2 GHz was measured. The results are shown in Table 2.

  In place of the reverse roll coater, a gravure coater (in the coater shown in FIG. 1, the coating roll 2 is replaced with a gravure roll. Travel speed of the support 5: 0.5 m / min, peripheral speed of the gravure roll: 5 m / The coating solution viscosity is 1700 mPa · s), and dried and passed through a 35 μm thick electromagnetic interference suppression sheet again through a gravure coater and overcoated with a thickness of 25 μm. Thus, an electromagnetic interference suppression sheet having a thickness of 60 μm was obtained. With respect to the obtained electromagnetic interference suppression sheet, in the same manner as in Example 1, transmission loss at actual specific gravity / theoretical specific gravity, 1 GHz and 2 GHz was measured. The results are shown in Table 2.

  Except that three 27μm thick electromagnetic interference suppression sheets obtained by applying with a gravure coater were laminated to three layers with a calender roll (thickness 81μm), and then press molded to 60μm thickness (surface pressure = 5MPa). In the same manner as in Example 3, an electromagnetic interference suppression sheet was obtained. With respect to the obtained electromagnetic interference suppression sheet, in the same manner as in Example 1, transmission loss at actual specific gravity / theoretical specific gravity, 1 GHz and 2 GHz was measured. The results are shown in Table 2.

[Comparative Example 1]
Electromagnetic interference with a thickness of 60 μm in the same manner as in Example 1 except that a die coat (running speed of support: 0.5 m / min, coating solution viscosity: 4000 mPa · s) was used instead of the reverse roll coater. A suppression sheet was obtained. With respect to the obtained electromagnetic interference suppression sheet, in the same manner as in Example 1, transmission loss at actual specific gravity / theoretical specific gravity, 1 GHz and 2 GHz was measured. The results are shown in Table 2.

  From Table 3, it can be seen that the electromagnetic interference suppression sheets of Examples 1 to 4 have higher transmission loss (absorption rate) than the comparative example.

It is a schematic explanatory drawing which shows the coating method of the magnetic coating material in this invention. It is a schematic explanatory drawing which shows the other application | coating method of the magnetic coating material in this invention. It is a schematic explanatory drawing which shows an example of the offset gravure coater used in this invention. It is a schematic explanatory drawing which shows an example of the reverse roll coater used in this invention. It is a schematic explanatory drawing which shows the other example of the reverse roll coater used in this invention. It is a schematic explanatory drawing which shows an example of the comma coater used in this invention. It is a schematic explanatory drawing which shows the other example of the comma coater used in this invention. It is the schematic which shows the shape of the microstrip line used for the measurement of the transmission loss in an Example.

Explanation of symbols

1 Coater 2,12,22,32,42,72 Coating roll 3,13,23,33,43,63,73 Magnetic paint 4,24,44 Pan 5,15,25,35,45,65,75 Support Body 6, 26, 36, 46, 66, 76 Backup roll 21 Offset gravure coater 27 Vibrating blade 28 Gravure roll 31, 41 Reverse roll coater 34, 64, 74 Paint weir 37 Cleaning blade 8, 38, 48 Weighing roll 39 Scraping off Can 40 Flexible blade 49 Pumping roll 54 Electromagnetic interference suppression sheet 61, 71 Comma coater 68, 78 Comma roll

Claims (10)

  An electromagnetic interference suppressor containing 30 to 80% by volume of flat soft magnetic powder and 20 to 70% by volume of a binder and having an actual specific gravity / theoretical specific gravity of 0.6 or more.   The specific gravity A and the actual specific gravity B when 30% to 80% by volume of the flat soft magnetic powder and 20% to 70% by volume of the binder are discharged, and the actual specific gravity B is expressed by the formula: {( The electromagnetic interference suppressor according to claim 1, satisfying a relationship of A−B) / B} × 100 ≦ 40%.   The electromagnetic interference suppressor according to claim 1, wherein the binder is rubber.   In the measurement of transmission loss using a microstrip line with impedance Z = 50Ω, when the electromagnetic interference suppressor has a thickness of 60 μm, the transmission loss (absorption rate) at 1 GHz is 10% or more, and the transmission loss at 2 GHz ( The electromagnetic interference suppressor according to any one of claims 1 to 3, wherein the absorption rate is 20% or more.   The electromagnetic interference suppressor according to any one of claims 1 to 4, wherein the flat soft magnetic powder has an average particle diameter of 5 to 100 µm and an aspect ratio of 5 to 100. A method of producing an electromagnetic interference suppressor by applying a magnetic coating containing a flat soft magnetic powder and a binder on a support and drying the coating,
The magnetic coating material is applied onto the support by a roll that is rotationally driven in a direction opposite to the direction in which the support is caused to travel, or in the same direction and at a peripheral speed different from the travel speed of the support. Method for manufacturing electromagnetic interference suppressor.   The manufacturing method of the electromagnetic interference suppression body of Claim 6 which apply | coats the said magnetic coating material on a support body using a gravure coater.   The manufacturing method of the electromagnetic interference suppression body of Claim 6 which apply | coats the said magnetic coating material on a support body using a reverse roll coater.   The manufacturing method of the electromagnetic interference suppression body which laminated | stacked two or more layers of the electromagnetic interference suppression body obtained with the manufacturing method in any one of Claims 6-8. A method for producing an electromagnetic interference suppressor, wherein the electromagnetic interference suppressor obtained by the production method according to any one of claims 6 to 9 is rotocured, high-pressure calender, or press vulcanized.

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