JP2013253122A - Composite magnetic material, method for manufacturing the same, antenna, and communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite magnetic material wherein tabular magnetic particles are excellently oriented in a resin and therefore a real part μr' of a complex magnetic permeability can be raised, a method for manufacturing the composite magnetic material, an antenna, and a communication device.SOLUTION: A composite magnetic material includes a resin having a cyclic structure in a main chain and having functional groups polymerizing by a monomer unit, and tabular magnetic particles. A method for manufacturing the composite magnetic material, and an antenna equipped with the magnetic material are also provided. Preferably, the resin is an epoxy resin, and more preferably, a dicyclopentadiene epoxy resin.

Description

  The present invention relates to a composite magnetic body, a method for manufacturing the same, an antenna, and a communication device, and particularly suitable for a high-frequency circuit board, a high-frequency electronic component, a magnetic sheet, an electromagnetic wave shielding sheet, a resin-bonded magnet, a magnetic recording medium, and an antenna. A composite magnetic body that can be used to obtain a real part μr ′ having a high complex permeability by satisfactorily orienting magnetic tabular grains in a polymer material, and a method for producing the same, and the composite magnetic body And a communication device such as a portable telephone and a portable information terminal provided with the antenna.

A magnetic material is known to be used as a composite magnetic material mixed and dispersed in an insulating material such as an organic polymer material because of its properties against electromagnetic waves, productivity, and ease of use.
This magnetic material is used for electronic components mounted on electronic devices, magnetic sheets, electromagnetic interference suppression sheets, electric products such as motors and transformers, and magnetic recording media such as video tapes and floppy (registered trademark) disks.

In recent years, with the increase in speed and density of information communication devices, there is a strong demand for downsizing and low power consumption of electronic components, circuit boards and antennas mounted on electronic devices, especially antennas for portable information devices. ing.
In general, the wavelength λg of the electromagnetic wave propagating in the substance is determined by the wavelength λo of the electromagnetic wave propagating in the vacuum, the real part εr ′ of the complex permittivity of the substance (hereinafter sometimes abbreviated as εr ′), and the real of the complex permeability. Using the part μr ′ (hereinafter sometimes abbreviated as μr ′),
λg = λo / (εr ′ · μr ′) ^1/2 (1)
It can be expressed as. According to this equation (1), as εr ′ and μr ′ increase, the shortening rate of the wavelength λg increases. Therefore, by increasing εr ′ and μr ′ of the magnetic material constituting the electronic component, the circuit board, the antenna, etc., the shortening rate of the wavelength λg is increased, so that the electronic component, the circuit board, the antenna, etc. can be downsized. It becomes possible.

  As a material with an increased wavelength shortening rate, a composite magnetic material in which magnetic particles are mixed and dispersed in an insulating material constituting an electronic component or a circuit board has been proposed (Patent Document 1). In this composite magnetic body, the wavelength shortening rate is increased by increasing μr ′.

By the way, when spherical magnetic particles are used for the composite magnetic body, the demagnetizing factor coefficient of each magnetic particle increases, and therefore it is generally difficult to increase μr ′ of the composite magnetic body. Are known.
Therefore, as the magnetic particles used for such applications, flat magnetic particles having a thickness of 10 μm or less are desired, and various aspect ratios (major axis / thickness) such as a flat shape, a scale shape, and a flake shape are large. Magnetic particles having various shapes have been proposed (see, for example, Patent Documents 2 and 3).

With such tabular magnetic particles, a high μr ′ is obtained in the plane direction with the lowest demagnetizing field coefficient, that is, the major axis direction. Therefore, in order to obtain a high μr ′ by effectively utilizing the effect of the demagnetizing factor, a composite magnetic material in which tabular magnetic particles are mixed and dispersed in an insulating material is used as an insulating material. It must be oriented in one direction.
As a method of orienting the flat magnetic particles, a method of passing a coating film containing flat magnetic fine particles formed on a substrate between the magnetic poles of a magnet (Patent Document 4), or a molding die incorporating a permanent magnet There has been proposed a method using the above (Patent Document 5).
In these methods, a resin is used as the insulating material, and the magnetic particles are oriented by applying a magnetic field in a state where the resin is fluid before being thermally cured or heated and melted.

JP 2004-087627 A Japanese Unexamined Patent Publication No. 63-35701 Japanese Patent Laid-Open No. 1-188606 Japanese Patent Laid-Open No. 57-127931 JP 2000-141392 A

  By the way, in the conventional method for orienting flat magnetic particles described in Patent Document 4 and Patent Document 5, a magnetic field is applied by applying a magnetic field in a state where the resin is fluid before heat curing or by heat melting. Even if the particles are oriented, there is a problem that the obtained composite magnetic body has a small μr ′.

  In addition, although the μr ′ of the individual soft magnetic tabular magnetic particles themselves is higher than that of the hard magnetic tabular magnetic particles having a large coercive force, the conventional magnetic field application method has a small soft magnetic force. The tabular magnetic particles have a problem that the orientation is poor and the μr ′ obtained as a whole of the composite magnetic material is small. In particular, when a composite magnetic body having a thickness of 100 μm or more is manufactured, there is a problem in that good μr ′ cannot be obtained.

  The present invention has been made in view of the above circumstances, and a composite magnetic body in which the real part μr ′ of the complex permeability is increased by flatly aligning the flat magnetic particles in the resin, and the production thereof. It is an object to provide a method, an antenna, and a communication device.

As a result of intensive studies to solve the above problems, the present inventors have obtained the following knowledge.
When conventional bisphenol-type epoxy resin and tabular magnetic particles are mixed, the resulting mixture has a functional group of the epoxy resin adsorbed on the surface of the tabular magnetic particles, and a polymer chain around the magnetic particles. Surrounded and long intertwined. In such a mixture in which the polymer chains are long entangled, the polymer chains may be sterically hindered to inhibit the orientation of the tabular magnetic particles.
Therefore, in order to improve the fluidity of the tabular magnetic particles, even if the amount of the solvent in the mixture is increased to make the viscosity macroscopically low, the influence of the steric hindrance of the polymer chain is still large, and the tabular magnetic The orientation of body particles will be inhibited.
On the other hand, if the polymer chain is shortened in order to reduce the influence of steric hindrance of the polymer chain, the condensation or bonding reaction between the polymer chains becomes insufficient, and as a result, the mechanical strength of the resulting composite magnetic material In some cases, the shape may not be maintained, and the shape may not be maintained, and cannot be used for electronic components, circuit boards, and the like.

Therefore, in order to reduce the influence of the steric hindrance of the polymer chain, by using a resin having a cyclic structure in the main chain that is flat and hardly entangled with the tabular magnetic particles, the orientation of the tabular magnetic particles by applying a magnetic field Found to improve. Furthermore, it was obtained by forming many bonds even when the polymer chain is short, by using a resin having a functional group that polymerizes by a monomer unit, rather than a functional group that polymerizes only at the terminal. It has been found that the mechanical strength of the composite magnetic material is improved and the shape can be easily maintained.
Furthermore, when a magnetic field is applied by molding a mixture in which the resin and the flat magnetic particles are mixed, the magnetic field is applied once or a plurality of times so that the lines of magnetic force are substantially parallel to the surface of the molded body. It has been found that the real part μr ′ of the complex magnetic permeability of the composite magnetic material is improved by applying it.
The present invention has been completed based on such findings.

  That is, the composite magnetic body of the present invention is characterized by including a resin having a cyclic structure in the main chain and a functional group that is polymerized in monomer units, and flat magnetic particles.

In this composite magnetic body, the resin is preferably a thermosetting resin.
The resin is preferably an epoxy resin.
The epoxy resin is preferably a dicyclopentadiene type epoxy resin.
The angle between the orientation direction of the tabular magnetic particles in the resin and the major axis direction of the tabular magnetic particles is preferably 20 ° or less.
The real part μr ′ of the complex magnetic permeability is preferably 7 or more.

  The method for producing a composite magnetic body of the present invention comprises a step of mixing a resin having a cyclic structure in the main chain and having a functional group that is polymerized in a monomer unit and a tabular magnetic particle to obtain a mixture. And

  After the step of obtaining the mixture, a molding step of molding the mixture into a predetermined shape, and an orientation in which a magnetic field is applied to the obtained molded body to orient the flat magnetic particles in the molded body in one direction. It is preferable to have a process and a drying / curing process for drying / curing the molded body.

  The antenna of the present invention comprises the composite magnetic material of the present invention.

  A communication apparatus according to the present invention includes the antenna according to the present invention.

According to the composite magnetic body of the present invention, since the main chain includes a resin having a cyclic structure in the main chain and a functional group that is polymerized in a monomer unit, and flat magnetic particles, the resin is flat and flat. Since it has a structure that is unlikely to be entangled with the magnetic particles, the influence of steric hindrance by the resin on the flat magnetic particles can be reduced. Therefore, a composite magnetic body having a good orientation of the tabular magnetic particles and a high real part μr ′ of complex permeability can be obtained.
Furthermore, since a resin having a functional group that is polymerized in monomer units is used, the resin bond becomes strong, and it is possible to have sufficient mechanical strength as a molded body for use in electronic parts and the like.

According to the method for producing a composite magnetic body of the present invention, there is a step of mixing a resin having a cyclic structure in the main chain and having a functional group that is polymerized in a monomer unit and a flat magnetic particle to obtain a mixture. In addition, it is possible to easily produce a composite magnetic body in which the orientation of the tabular magnetic particles is good and the complex permeability has a high real part μr ′.
Furthermore, after the step of obtaining the mixture, a molding step of molding the mixture into a predetermined shape, and an orientation step of applying a magnetic field to the obtained molded body to orient the flat magnetic particles in the molded body in one direction. And a drying / curing step for drying / curing the molded body, it is easy to obtain a composite magnetic body in which the orientation of the tabular magnetic particles is better and the real part μr ′ of the complex permeability is higher. Can be produced.

  According to the antenna of the present invention, since the composite magnetic body of the present invention is provided, the entire antenna can be reduced in size by using the composite magnetic body having a high real part μr ′ of the complex permeability. Therefore, a further miniaturized antenna can be provided.

  According to the communication device of the present invention, since the antenna of the present invention is provided, the communication device as a whole can be reduced in size by using a miniaturized antenna. Therefore, a further miniaturized communication apparatus can be provided.

It is a schematic block diagram which shows the orientation apparatus for implementing the orientation method A of this invention. It is a schematic block diagram which shows the orientation apparatus for implementing the orientation method B of this invention. It is a schematic block diagram which shows the orientation apparatus for implementing the orientation method C of this invention. It is a schematic diagram which shows operation | movement of the orientation apparatus for enforcing the orientation method C of this invention. It is a schematic block diagram which shows the orientation apparatus for implementing the orientation method D of this invention. It is a schematic diagram which shows the electric power feeding method of the monopole antenna which is an example of the antenna of one Embodiment of this invention. It is a perspective view which shows an example of the kind of portable telephone of the communication apparatus of one Embodiment of this invention. It is a perspective view which shows another example of a kind of portable telephone of the communication apparatus of one Embodiment of this invention. It is a perspective view which shows another example of a kind of portable telephone of the communication apparatus of one Embodiment of this invention. It is a perspective view which shows another example of a kind of portable telephone of the communication apparatus of one Embodiment of this invention. It is a figure which shows a mode that a slurry and a dispersion medium are stirred using an airtight container.

The composite magnetic body according to the present invention, a manufacturing method thereof, an antenna, and a mode for carrying out a communication device will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

[Composite magnetic material]
The composite magnetic body of the present embodiment includes a resin having a cyclic structure in the main chain and a functional group that is polymerized in monomer units, and flat magnetic particles.

<resin>
Said resin is resin which has a cyclic structure in a principal chain, and has a functional group which polymerizes by a monomer unit. The resin is not particularly limited as long as it is a resin capable of obtaining a fluid mixture having a low viscosity when mixed with flat magnetic particles, and includes a thermosetting resin, a thermoplastic resin, and an ultraviolet curable resin. Can be used.

Such resins include epoxy resins, silicone resins, phenol resins, polyimide resins, polybenzoxazole resins, polyphenylene resins, polybenzocyclobutene resins, polyarylene ether resins, polycyclohexane resins, polyester resins, fluororesins, polyolefin resins. , Polycycloolefin resin, cyanate resin, polyphenylene ether resin, polystyrene resin, acrylic resin, methacrylic resin, urethane resin, urethane-acrylic resin, epoxy-acrylic resin, and the like. These resins may be used alone or in combination of two or more.
Among these, a thermosetting resin is preferable because it has solubility in many solvents and the viscosity can be easily adjusted, and among the thermosetting resins, an epoxy resin and a polycycloolefin resin are preferable.

  Here, as an example of an epoxy resin as a resin having a cyclic structure in the main chain, a dicyclopentadiene type epoxy resin (formula (1)) having only a cyclic structure in the main chain or a naphthalene type epoxy resin (formula ( 2)) is preferably used.

式（２）中、Ｒ_１は、水素またはメチル基である。

In formula (2), R ₁ is hydrogen or a methyl group.

  Moreover, as resin which has a linear structure in a principal chain, resin (Formula (3)) of the structure which has a short linear structure of C = 1-3 in the linear chain of a cresol novolak-type epoxy resin is mentioned. In formula (3), X is a linear structure having a short alkyl chain of C = 1 to 3, and a linear structure of C = 1 is preferable.

式（３）中、ＸはＣ＝１〜３のアルキル鎖、Ｒ_２は、水素、分子量が１５〜１８０の範囲のアルキル基、アリール基のいずれかである。
このＸとしては、例えば、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、tert-ブチル基、フェニル基、ベンジル基、トリル基等があげられる。

In formula (3), X is an alkyl chain having C = 1 to 3, R ₂ is hydrogen, an alkyl group having a molecular weight in the range of 15 to 180, or an aryl group.
Examples of X include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, phenyl group, benzyl group and tolyl group.

Further, as a resin having a linear structure in the main chain, a resin (formula (4)) having a structure having a short linear structure of C = 1 to 3 in the linear chain of a dicyclopentadiene type epoxy resin should be used. Can do.
In formula (4), X is a linear structure having an alkyl chain of C = 1 to 3.
Examples of X include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, phenyl group, benzyl group and tolyl group.

Even if the resin having the structure described above is a resin that is difficult to be entangled with the flat magnetic particles, the real part μr ′ of the complex magnetic permeability of the composite magnetic material may be reduced as the polymer chain becomes longer. Accordingly, n in the above formulas (1), (3), and (4) is preferably 0 to 3, and more preferably n = 0.
That is, it is preferable to use a monomer alone or use a combination of a monomer and an oligomer as appropriate.

For example, in order to obtain a high μr ′, it is preferable to use a dicyclopentadiene type epoxy resin of the formula (1) where n = 1, and the resin has the functions of flexibility and peelability from the substrate. When it is desired to impart, it is preferable to use a combination of a dicyclopentadiene type resin and a resin that imparts flexibility to the resin.
As a resin that imparts flexibility, when it is molded and cured by mixing with a dicyclopentadiene type resin and flat magnetic particles described later, flexibility and stretchability are imparted to the obtained cured body. The resin is not particularly limited, and for example, a resin having excellent flexibility such as an epoxy resin, a silicone resin, a urethane resin, and a polyamide resin is preferable. Alternatively, a modified epoxy resin modified with urethane, polyethylene, ethylene propylene, or the like as the epoxy resin, or a propylene oxide-added epoxy resin obtained by adding propylene oxide to the epoxy resin can be used.

  When a dicyclopentadiene type resin and a resin imparting flexibility are used in combination, it is preferable to contain the dicyclopentadiene type resin in an amount of 50% by mass to 90% by mass of the total amount of the resin. By setting the content of the dicyclopentadiene type resin in the above range, a high μr ′ can be obtained.

About said resin, you may add a thermoplastic elastomer as needed. By adding this thermoplastic elastomer, the mechanical strength and shape processability of the composite magnetic material can be improved. Therefore, the composite magnetic body to which this thermoplastic elastomer is added is excellent in toughness, flexibility and deformability.
As the thermoplastic elastomer, one or more selected from the group of styrene, olefin, vinyl chloride, urethane, ester, and amide can be used.
The amount of the thermoplastic elastomer added may be adjusted as appropriate in consideration of the heat resistance required for the application of the composite magnetic material.

<Tabular magnetic particles>
The material constituting the tabular magnetic particles is not particularly limited as long as it is a material having magnetism. For example, nickel (Ni), iron (Fe), cobalt (Co), gadolinium (Gd), terbium ( Tb), a ferromagnetic metal such as dysprosium (Dy), a paramagnetic metal such as molybdenum (Mo) or the like, or a metal containing at least one of these metals can be used.
These metals or alloys may contain diamagnetic metals such as copper (Cu), zinc (Zn), and bismuth (Bi).

Examples of these alloys include two-element alloys and three-element alloys.
Examples of the two-element alloys include Fe-Ni alloys such as Permalloy (registered trademark) that exhibit a soft magnetism with a holding power of 50 oersted or less, Fe-Si alloys, Fe-Co alloys, Fe-Cr alloys, and the like.
Examples of the ternary alloy include Fe—Ni—Mo alloys such as Supermalloy (registered trademark), Fe—Si—Al alloys such as Sendust (registered trademark), Fe—Cr—Si alloys, and the like.
Among these alloys, as an Fe—Ni alloy, an alloy of Ni 78% by mass—Fe 22% by mass is easily obtained with an average thickness of tabular magnetic particles of 0.2 μm or less and an average major axis of 2 μm or less. A composite magnetic body having high magnetic permeability and low magnetic loss can be obtained, which is preferable.

  A metal element that is not included in the alloy and has similar properties to the alloy (a metal that is close to the metal in the alloy in the periodic table), such as aluminum (Al), chromium (Cr), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), niobium (Nb), molybdenum (Mo), indium (In), tin (Sn), etc. Two or more kinds may be appropriately selected and added.

When the above metal element is added to the alloy, the content of the metal element is preferably 0.1% by mass or more and 90% by mass or less, preferably 1% by mass with respect to the total mass of the metal element and the alloy. It is more preferably 12% by mass or less, and further preferably 1% by mass or more and 5% by mass or less.
Here, the reason why the content of the metal element is limited to the above range is that when the content of the metal element is less than 0.1% by mass, it is sufficient to flatten the spherical magnetic particles described later. On the other hand, when the content ratio exceeds 90% by mass, since the magnetic moment of the metal element itself is small, the saturation magnetization of the entire plate-like magnetic particle becomes small. This is because the obtained μr ′ is also small.

  Particularly, a group of soft metals such as aluminum (Al), zinc (Zn), indium (In), and tin (Sn) in that the aspect ratio is high and a high μr ′ composite magnetic body is easily obtained as a result. It is preferable to use an iron-nickel alloy containing one or more metal elements selected from 1 to 12% by mass, preferably 1 to 5% by mass.

  Among these, the nickel-iron-zinc (Ni-Fe-Zn) alloy has a large aspect ratio because the addition of Zn to the Fe-Ni alloy increases the workability of spherical magnetic particles described later. It is preferable because a flat magnetic powder is easily obtained. As the composition ratio of the alloy, for example, an alloy of Ni 75% by mass—Fe 20% by mass—Zn 5% by mass, Ni 76% by mass—Fe 20% by mass—Zn 4% by mass, and the like can be suitably used.

  The tabular magnetic particles are preferably insulating tabular magnetic particles. By using insulating tabular magnetic particles, it is possible to suppress the formation of a conductive path due to the contact between the tabular magnetic particles in the composite magnetic material. The dielectric loss can be reduced. In the insulating tabular magnetic particles, it is sufficient that at least the surfaces of the particles have insulating properties.

The method for making the tabular magnetic particles insulative is not particularly limited, and examples thereof include a method of forming an insulating oxide film of about 5 nm on the surface of the tabular magnetic particles.
Usually, by handling the tabular magnetic particles in the air, an oxide film is naturally formed on the surface of the tabular magnetic particles, but the insulating film is insufficient in the naturally formed oxide film, It is difficult to reduce the dielectric loss of the composite magnetic material. Therefore, in order to reduce the dielectric loss of the composite magnetic material, the surface of the tabular magnetic particles is about 5 nm by heat treatment at a temperature of 50 ° C. or more and 200 ° C. or less for about 1 hour to several hours. It is preferable to form an insulating oxide film.

  Further, an insulating coating having a composition different from that of the tabular magnetic particles may be formed on the surface of the tabular magnetic particles. Examples of such a composition include inorganic substances such as silicon oxide and phosphate, or organic substances such as resins and surfactants. These insulating films may be formed on the surface of tabular magnetic particles having an oxide film (including oxide films formed by natural oxidation or heat oxidation), or on the surface of tabular magnetic particles having no oxide film. It may be formed.

The flat magnetic particles have an average thickness of 0.1 μm or more and 10 μm or less, more preferably 0.1 μm or more and 1 μm or less.
In particular, when this flat magnetic particle is used in a high frequency band of 100 MHz or more, the average thickness is more preferably 0.1 μm or more and 0.5 μm or less.
Here, when the average thickness of the tabular magnetic particles is less than 0.1 μm, it is difficult to manufacture the tabular magnetic particles themselves, and it is difficult to handle the composite magnetic body, and as a result, the orientation is good and This is not preferable because it is difficult to obtain a composite magnetic material having a high μr ′.
On the other hand, if the average thickness of the tabular magnetic particles exceeds 10 μm, an eddy current or the like is generated when a high frequency is applied, and μr ′ of the obtained composite magnetic material is lowered, which is not preferable.

The average major axis (maximum length in the grain) of the tabular magnetic particles is preferably 0.2 μm or more and 100 μm or less, particularly when the tabular magnetic particles are used in a high frequency band of 100 MHz or more. The average major axis is more preferably 0.2 μm or more and 20 μm or less, and further preferably 0.3 μm or more and 10 μm or less.
Here, when the average major axis of the tabular magnetic particles is less than 0.2 μm, it is difficult to manufacture the tabular magnetic particles themselves, and it is also difficult to handle the composite magnetic body. As a result, the orientation is good and This is not preferable because it is difficult to obtain a composite magnetic material having a high μr ′.
On the other hand, if the average major axis of the tabular magnetic particles exceeds 100 μm, the dispersion stability in the resin of the obtained composite magnetic material is lowered and the desired μr ′ cannot be obtained, which is not preferable.

An average aspect ratio (length / thickness) obtained by selecting a plurality of tabular magnetic particles and averaging the aspect ratios (length / thickness) of these tabular magnetic particles is 2 or more and 20 or less. It is preferable that it is 6 or more and 15 or less.
Here, when the average aspect ratio (length / thickness) of the tabular magnetic particles is less than 2, the effect of the demagnetizing field coefficient due to the particle shape is reduced, and as a result, the effective applied when producing the composite magnetic material. This is not preferable because the magnetic field is reduced and μr ′ of the obtained composite magnetic material is reduced.

On the other hand, if the average aspect ratio exceeds 20, the shape of the tabular magnetic particles is too flat, the space between the magnetic particles is narrowed, and it is easy to form a space in which the insulating material does not easily enter, As a result, bubbles are likely to be generated in the composite magnetic material, and the presence of the bubbles lowers μr ′, which is not preferable.
Further, when the average aspect ratio of the tabular magnetic particles becomes large, the mechanical strength of the tabular magnetic particles themselves may be lowered. Therefore, in order to ensure a desired mechanical strength, the average aspect ratio is 15 The following is preferable, and practically about 20 is the upper limit.

  The flat magnetic particles can be produced, for example, by subjecting spherical magnetic particles synthesized by a liquid phase reduction method, an atomizing method, etc. to a flattening treatment in a solvent. Examples of the flattening apparatus include a bead mill, a kneader, a roll mill, a planetary ball mill, and a jet mill. In addition, a dispersion medium (media) such as a ball used in these apparatuses may be any medium that does not contaminate the spherical magnetic particles and can effectively apply shear energy, such as a metal such as aluminum or steel. Metal oxides such as alumina, zirconia and titania, inorganic oxides such as silicon dioxide, nitrides such as aluminum nitride and silicon nitride, carbides such as silicon carbide, various glasses such as soda glass, lead glass and high specific gravity glass Can be mentioned.

The average primary particle size of the spherical magnetic particles is not particularly limited as long as a desired shape can be obtained, but a spherical magnetic material having an average primary particle size of 10 nm or more and 2 μm or less prepared by a liquid phase reduction method. It is preferable to use particles.
If the average primary particle diameter of the spherical magnetic particles is in the above range, the surface of the spherical magnetic particles is highly active, the affinity between the particles is increased, and adhesion between the particles can be promoted, which is preferable. .

As a preferred method for producing the flat magnetic particles, a slurry in which spherical magnetic particles having an average particle diameter of 0.5 μm or less are dispersed in a solution containing a surfactant and a dispersion medium can be sealed. The total volume of the slurry and the dispersion medium is filled so as to be the same as the volume in the closed container, and the slurry is stirred together with the dispersion medium in a sealed state, and the spherical magnetic particles are mixed together. There is a method in which one flat magnetic particle is obtained from a plurality of spherical magnetic particles by deforming and fusing.
By this method, it is possible to easily produce tabular magnetic particles having an aspect ratio of 2 or more and 20 or less and having a substantially uniform shape such as thickness and major axis.

Hereinafter, the manufacturing method of this flat magnetic particle is demonstrated in detail based on FIG.
First, spherical magnetic particles 202 having an average particle diameter of 0.5 μm or less are dispersed in a solution containing a surfactant to obtain a slurry 203.
The composition of the magnetic particles 202 is exactly the same as the composition of the above-mentioned tabular magnetic particles.
As the surfactant, a surfactant containing an element such as nitrogen, phosphorus, or sulfur that is compatible with the surface of the magnetic particle 202 is preferable, and examples thereof include nitrogen-containing block copolymers, phosphates, and polyvinylpyrrolidone. .

  The solvent for dissolving the surfactant is not particularly limited, but an organic solvent is preferable in consideration of the need to prevent oxidation of the metal element contained in the magnetic particles, and in particular, xylene, toluene, cyclopentanone. Nonpolar organic solvents such as cyclohexanone are preferred.

Next, the slurry 203 and the dispersion medium 204 are filled into a sealable container 201 so that the total volume of the slurry 203 and the dispersion medium 204 is the same as the volume in the sealed container 201, and the slurry 203 is combined with the dispersion medium 204. Stirring is performed in a sealed state, and the spherical magnetic particles 201 are deformed into a flat shape while being fused with each other to obtain flat magnetic particles.
Here, the filling amount of the slurry 203 and the dispersion medium 204 into the sealed container 201 is the same as the volume in the sealed container 201. In other words, the slurry 203 and the dispersion medium 204 are filled in the sealed container 201 without a gap.

Here, when the slurry 203 and the dispersion medium 204 are added so that there is a gap in the sealed container 201, when the uniaxial rotating body 205 rotates, the liquid level of the slurry 203 and the dispersion medium 204 is reduced by centrifugal force. The vicinity of the central axis is low, and the peripheral part is mortar-shaped.
The mechanical stress applied to the slurry 203 and the dispersion medium 204 including the spherical magnetic particles 202 by the uniaxial rotating body 205 escapes into the mortar-like space, and therefore the entire inside of the sealed container 201 is interposed via the dispersion medium 204. The mechanical stress propagated to the spherical magnetic particles 202 becomes non-uniform, which causes the thickness of the obtained tabular magnetic particles to vary. Such thickness variations, cracks, and chipping of the tabular magnetic particles cause an increase in magnetic loss.

  Further, the magnetic particles having a flat plate shape near the bottom (near the central axis) of the mortar-shaped space are discharged into the mortar-shaped space together with the dispersion medium 204 and receive an irregular impact, such as cracking or chipping. May occur.

  Therefore, as shown in FIG. 11, the uniaxial rotating body 205 rotates at high speed by applying mechanical stress in a state where the sealed container 201 is filled with the slurry 203 containing the spherical magnetic particles 202 and the dispersion medium 204. Even if it does, there is no possibility that a mortar-shaped space may arise. Therefore, the mechanical stress applied to the slurry 203 containing the spherical magnetic particles 202 and the dispersion medium 204 by the uniaxial rotating body 205 is uniformly applied to the spherical magnetic particles 202 via the dispersion medium 204 in the entire sealed container 201. There is no possibility that the thickness of the propagating and obtained tabular magnetic particles varies. Further, since the tabular magnetic particles are not subjected to an irregular impact when mechanical stress is applied, almost no cracks or chips are generated.

  The sealed container 201 may be provided with an inlet and an outlet for introducing / extracting the slurry 203 into / from the sealed container 201 so that the slurry 203 is circulated into the sealed container 201. In this case, the dispersion medium 204 is stored in the sealed container 201 in advance, and the slurry 203 in which the spherical magnetic particles 202, the surfactant, and the solvent are mixed is introduced from the inlet, and there is no space in the sealed container 201. And the slurry 203 discharged from the outlet may be returned to the sealed container 201 again.

  The dispersion medium 204 needs to have a higher hardness than the spherical magnetic particles 202, such as metal balls such as aluminum, steel (steel), stainless steel, and lead, alumina, zirconia, silicon dioxide, titania, and the like. Spherical sintered body made of metal oxide or inorganic oxide, spherical sintered body made of inorganic nitride such as silicon nitride, spherical sintered body made of inorganic carbide such as silicon carbide, soda glass, lead glass, high specific gravity glass In particular, zirconia, steel (steel), stainless steel and the like having a specific gravity of 6 or more are preferable from the viewpoint of efficiency.

  The mechanical stress is applied to the spherical magnetic particles 202 when the dispersion media 204 collide with each other or when the dispersion media 204 collide with the inner wall of the sealed container 201. It is done by the impact given. In this case, as the number of collisions between the dispersion media 204 or between the dispersion media 204 and the inner wall of the sealed container 201 increases, the fusion property and deformability of the spherical magnetic particles 202 improve.

Here, as the average particle diameter of the dispersion medium 204 is smaller, the number of the dispersion medium 204 existing per unit volume is increased and the number of collisions is increased. Therefore, the fusibility and deformability of the magnetic particles 202 are also improved. On the other hand, if the average particle size of the dispersion medium 204 is too small, it is difficult to separate the dispersion medium 204 from the slurry 203. Therefore, the average particle diameter of the dispersion medium 204 needs to be at least 0.03 mm or more, preferably 0.04 mm or more.
On the other hand, if the average particle size of the dispersion medium 204 is too large, the number of collisions is reduced, so that the deformation and fusion properties between the spherical magnetic particles 202 are lowered. Therefore, the upper limit of the average particle diameter of the dispersion medium is 3.0 mm.

The sealed container 201 preferably has a configuration in which the dispersion medium 204 can be rotated at a high speed together with the slurry 203 by rotating a uniaxial rotating body 205 such as a disk, a screw, a blade, or a pin at a high speed.
Since the sealed container 201 is a simple uniaxial rotation system, it can be easily increased in size and is advantageous in industrial production.

  The rotational speed of the uniaxial rotating body 205 is determined by the size of the sealed container 201. For example, in the case of the sealed container 201 having an inner diameter of 120 mm, the slurry 203 containing the spherical magnetic particles 202 and the uniaxial rotating body 205 are uniaxial so that the flow velocity near the outer peripheral end 205a in the radial direction of the uniaxial rotating body 205 is 5 m / second or more. It is preferable to set the rotation speed of the rotator 205, and it is more preferable to set the rotation speed of the uniaxial rotator 205 to be 8 m / sec or more.

  In addition, when the internal volume of the airtight container 201 is small, there exists a possibility that the spherical magnetic particle 202 may remain in the obtained flat magnetic particle. The remaining spherical magnetic particles 202 increase the magnetic loss or the orientation of the tabular magnetic particles due to contact between the spherical magnetic particles 202 or contact between the spherical magnetic particles 202 and the tabular magnetic particles. There is a risk of obstruction. Therefore, the tabular magnetic particles are preferably 90% by mass or more, more preferably 95% by mass or more, and still more preferably 99% by mass or more of the total amount of the magnetic particles, and are substantially free of the spherical magnetic particles 202. It is desirable.

Here, the reason why the spherical magnetic particles 202 remain when the inner volume of the sealed container 201 is small is that mechanical stresses such as the corners of the sealed container 201 and the joint between the uniaxial rotating body 205 and the sealed container 201 are sufficiently transmitted. This is probably because the dead space is relatively large. Therefore, when the inner volume of the sealed container 201 is increased, the dead space is relatively reduced. Therefore, the mechanical stress is sufficiently transmitted to the spherical magnetic particles 202, and the fusion property and deformability of the spherical magnetic particles 202 are increased. As a result, the residual spherical magnetic particles 202 are reduced, and the substantially spherical magnetic particles 202 are eliminated.
Thus, the volume of the sealed container 201 in which substantially spherical magnetic particles 202 do not remain is preferably 1 L or more, more preferably 5 L or more.
As described above, the spherical magnetic particles 202 are deformed while being fused by the mechanical stress applied by the uniaxial rotating body 205 to become flat magnetic particles.

Next, the tabular magnetic particles are separated from the dispersion medium 204 and the solvent.
The separation method is not particularly limited as long as the solvent can be removed from the slurry after preparing the flat magnetic particles, and examples thereof include heat drying, vacuum drying, freeze drying, and the like, but vacuum drying is preferable in terms of drying efficiency. In order to increase the drying efficiency, some solvent may be removed by a method such as solid-liquid separation before the drying step. As a solid-liquid separation method, a normal method such as a filtration operation such as a filter press or suction filtration, or a centrifugal separation operation using a decanter or a centrifuge may be used.

  The tabular magnetic particles from which the solvent has been removed may be heat-treated at 50 ° C. or more and 200 ° C. or less for 1 hour or more and several hours or less. By this heat treatment, an oxide film can be formed on the surface of the tabular magnetic particles, and insulating tabular magnetic particles can be obtained.

  Here, in particular, in consideration of the case of using in a high frequency band, the above plate-like magnetic particles are used, but the plate shape, rod shape, flat shape having a thickness, major axis and aspect ratio within the above range, Magnetic particles of various shapes such as scales and flakes can also be used.

The content of the tabular magnetic particles in the total amount of the composite magnetic material is preferably 10% by mass to 70% by mass, and more preferably 30% by mass to 60% by mass.
Here, when the content of the tabular magnetic particles is less than 10% by mass, the ratio of the tabular magnetic particles is too small, and the μr ′ of the obtained composite magnetic body becomes too low, and as a result. This is not preferable because a desired μr ′ cannot be secured.
On the other hand, when the content of the tabular magnetic particles exceeds 70% by mass, the ratio of the tabular magnetic particles is too large, and therefore the amount of the resin is relatively small, and the tabular magnetic particles and the resin Is not preferable because a slurry with low viscosity and fluidity cannot be obtained, and the orientation of the tabular magnetic particles in the subsequent process becomes insufficient.
Moreover, it is preferable that spherical magnetic particles are not contained in this composite magnetic body.

The angle formed by the orientation direction of the tabular magnetic particles in the composite magnetic body and the major axis direction of the tabular magnetic particles is preferably 20 ° or less, more preferably 0 ° or more and 15 ° or less, and still more preferably. It is 0 degree or more and 10 degrees or less.
When the major axis direction of the tabular magnetic particles is inclined within the above range with respect to the orientation direction of the tabular magnetic particles, a composite magnetic body having a high μr ′ can be obtained.
Here, the “orientation direction” is the direction in which the long axes of the tabular magnetic particles are oriented, that is, the long axis direction of a plurality of tabular magnetic particles when the cross section of the composite magnetic body is observed. The direction in which the standard deviation of the angle is the smallest.

The μr ′ of the composite magnetic material is preferably 7 or more and more preferably 10 or more when used in a high frequency band of 100 MHz or more.
Here, the reason why μr ′ is set to 7 or more is that, as μr ′ increases, the wavelength shortening rate in the high frequency band increases, and therefore, electronic components and circuit boards to which this composite magnetic material is applied can be further miniaturized. Because it becomes.
In the present embodiment, μr ′ means a value measured with a material analyzer.

[Production Method of Composite Magnetic Material]
The method for producing a composite magnetic body of the present embodiment includes a step of obtaining a mixture by mixing a resin having a cyclic structure in the main chain and having a functional group that is polymerized in monomer units, and flat magnetic particles.
Here, in order to obtain a composite magnetic body having a higher μr ′, after the step of obtaining the mixture, a molding step of molding the mixture into a predetermined shape, and applying a magnetic field to the obtained molded body, the molded body It is preferable to have an orientation process for orienting the tabular magnetic particles therein in one direction and a drying / curing process for drying / curing the molded body.

Next, the manufacturing method of the composite magnetic body of this embodiment is demonstrated in detail.
<Preparation of mixture>
First, a resin having a cyclic structure in the main chain and having a functional group that is polymerized in monomer units, tabular magnetic particles, and a curing agent and a solvent as required are prepared.

  As the resin having a cyclic structure in the main chain and having a functional group that is polymerized in a monomer unit, any resin can be used as long as it can obtain a low viscosity and fluid mixture when mixed with flat magnetic particles, Although not particularly limited, a thermosetting resin, a thermoplastic resin, or an ultraviolet curable resin can be used.

Such resins include epoxy resins, silicone resins, phenol resins, polyimide resins, polybenzoxazole resins, polyphenylene resins, polybenzocyclobutene resins, polyarylene ether resins, polycyclohexane resins, polyester resins, fluororesins, polyolefin resins. , Polycycloolefin resin, cyanate resin, polyphenylene ether resin, polystyrene resin, acrylic resin, methacrylic resin, urethane resin, urethane-acrylic resin, epoxy-acrylic resin, and the like. These resins may be used alone or in combination of two or more.
Among these, a thermosetting resin is preferable because it has solubility in many solvents and the viscosity can be easily adjusted, and among the thermosetting resins, an epoxy resin and a polycycloolefin resin are preferable.

For example, as an epoxy resin having a cyclic structure in the main chain, a dicyclopentadiene type epoxy resin having only a cyclic structure in the main chain represented by the above formula (1), and a naphthalene type epoxy represented by the formula (2) Resin.
Moreover, as an epoxy resin which has a linear structure in a principal chain, the cresol novolak-type epoxy resin which has the short linear chain of C = 1-3 represented by Formula (3) mentioned above, It represents with Formula (4). A dicyclopentadiene type epoxy resin having a short straight chain of C = 1 to 3 is mentioned.

Even if the resin having the above structure is a resin that is not easily entangled with the flat magnetic particles, if the polymer chain becomes long, the μr ′ of the composite magnetic material may be reduced. Accordingly, n in the above formulas (1), (3), and (4) is preferably 0 to 3, and more preferably n = 0.
That is, it is preferable to use a monomer alone or use a combination of a monomer and an oligomer as appropriate.

The magnetic material composing the tabular magnetic particles is exactly the same as the magnetic material described in the above-mentioned <Platform magnetic particles>, and thus the description thereof is omitted.
In addition, the thickness, major axis, aspect ratio (length / length) described in the above-mentioned item [Composite magnetic substance] are also used for the thickness, major axis, aspect ratio (length / thickness) and production method of the tabular magnetic particles. (Thickness) and the manufacturing method are completely the same, and the description is omitted.

What is necessary is just to adjust suitably the kind and addition amount of a hardening | curing agent according to resin to be used.
When an epoxy resin is used as the above resin, a tertiary amine is preferable in that the condensation reaction between epoxy groups is promoted to improve the mechanical strength of the composite magnetic body.
Examples of the tertiary amine include 1-isobutyl-2-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and the like. It is done.
In consideration of the point of promoting the condensation reaction of the functional group, the addition amount of the curing agent may be 0.5% by mass to 3% by mass with respect to the total mass of the resin.

In addition, a curing agent having a cyclic structure is preferable in the same manner as the above-described resin in that the influence of steric hindrance on the tabular magnetic particles is reduced and the μr ′ of the composite magnetic material is improved.
Examples of the curing agent having a cyclic structure include a phenol novolac type curing agent, a zylock type curing agent, a dicyclopentadiene type curing agent, and the like. These curing agents are preferably added in the same amount as the resin because the driving force for polymerizing the resin is weak compared to tertiary amines and the like.

The solvent is not particularly limited as long as it can dissolve the above-mentioned resin. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetyl acetone, cyclohexanone, benzene, toluene, xylene, ethyl benzene, etc. Aromatic hydrocarbons, diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dimethyl Amides such as formamide, N, N-dimethylacetamide and N-methylpyrrolidone are preferably used.
These solvents may be used alone or in combination of two or more. In particular, a solvent having a high boiling point such as cyclohexanone or xylene is preferable because it can suppress thickening of the slurry due to volatilization of the solvent.

The content of the tabular magnetic particles in this mixture is 10 volumes with respect to the volume (resin + curing agent + tabular magnetic particles) when the volatile components in the mixture are hardened and become solid. % To 60% by volume, more preferably 30% to 50% by volume.
Here, if the content of the tabular magnetic particles is less than 10% by volume, the tabular magnetic particles are too small and the magnetic properties as the composite magnetic material are deteriorated. On the other hand, the tabular magnetic particles are contained. If the rate exceeds 60% by volume, there are too many tabular magnetic particles, the fluidity of the mixture containing the tabular magnetic particles, the resin, the curing agent, and the solvent decreases, and the moldability decreases. Therefore, it is not preferable.

These flat magnetic particles, resin, curing agent and solvent are mixed to obtain a mixture. In this case, the viscosity of the mixture can be adjusted by appropriately adjusting the amount of the solvent added.
The mixing device is not particularly limited as long as the flat magnetic particles, the resin, the curing agent, and the solvent can be uniformly mixed to form a slurry mixture. For example, a roll mill, a self-revolving mixer, and a homogenizer are not limited. And an ultrasonic homogenizer and a stirrer.

The viscosity of the mixture is preferably 0.1 Pa · S or more and 10 ⁶ Pa · S or less, more preferably 0.3 Pa · S or more and 10 ⁴ Pa · S or less.
Here, when the viscosity is less than 0.1 Pa · S, the fluidity becomes too high and the productivity in the drying process is deteriorated. On the other hand, when the viscosity exceeds 10 ⁶ Pa · S, the viscosity is too high. Therefore, the orientation of the tabular magnetic particles is difficult to occur, and as a result, the orientation of the tabular magnetic particles in the composite magnetic material is lowered, which is not preferable.
Thus, by setting the content of the tabular magnetic particles to 10 volume% or more and 60 volume% or less, and setting the viscosity of the mixture to 0.1 Pa · S or more and 10 ⁶ Pa · S or less, μr ′ is formed. It is possible to obtain a composite magnetic body in which the mechanical strength of the body is balanced.

<Molding>
The molding method is not particularly limited as long as it can maintain a certain shape during the step of applying a magnetic field to the mixture.
Further, the shape and size of the molded body are not particularly limited, and for example, it may be molded into a sheet shape or a film shape, or may be molded into a shape having a thickness such as a rectangular parallelepiped shape.
A sheet or film is preferred because it can be easily obtained by applying the mixture to the substrate of the sheet or film and is excellent in mass productivity.

  In the case of molding into a sheet or film, for example, when the viscosity of the mixture is 10 Pa · S or less, a doctor blade method, a bar coating method, or the like can be used, and the viscosity of the mixture exceeds 10 Pa · s. In some cases, a die coating method or the like can be used. Moreover, when shape | molding in a shape with thickness, the method etc. which pour a mixture into the type | molds of arbitrary shapes are mentioned, for example.

In a state where the mixture is simply formed into a sheet shape, a film shape, a rectangular parallelepiped shape or the like, the tabular magnetic particles may be oriented in random directions and the orientation may not be sufficient.
Therefore, a magnetic field is applied to the molded body formed into a sheet shape, a film shape, a rectangular parallelepiped shape, or the like, and the flat magnetic particles in the molded body are oriented.

<Orientation>
The method for orienting the tabular magnetic particles in the compact is not particularly limited as long as a magnetic field is applied so that the tabular magnetic particles in the compact can be oriented in one direction. If the magnetic field lines are bent, the tabular magnetic particles cannot be oriented in one direction. Therefore, it is necessary to apply the magnetic field so that the generated magnetic field lines are substantially parallel to the surface of the molded body.
As such an alignment method, there are the following four alignment methods.

(1) Orientation method A
FIG. 1 is a schematic configuration diagram showing an orientation apparatus for carrying out orientation method A in the method for producing a composite magnetic body of the present invention. The above mixture (not shown) is an upper surface of a sheet-like or film-like substrate 1. This is an example of an apparatus for orienting plate-like magnetic particles in the coating film 2 by magnetic lines of force H generated by applying a magnetic field to the coating film 2 applied to the coating film 2.

  The aligning device 11 includes a coating means 12 having a dispenser for coating the mixture (not shown) on the upper surface of the substrate 1 that travels in the direction of the arrow in the figure to form the coating film 2, and the coating film 2. A pair of magnets 13a and 13b that are respectively provided on both sides in the width direction and that orient the flat magnetic particles in the coating film 2 by magnetic lines H generated by applying a magnetic field to the coating film 2 along the width direction; And a drying means 14 for drying the coating film 2 in which the flat magnetic particles are oriented by the magnetic field lines H. The magnets 13a and 13b are arranged so that the opposing poles are different from each other.

In this orientation device 11, since a magnetic field is generated from the N pole of the magnet 13a toward the S pole of the magnet 13b, the coating film 2 passing between the magnets 13a and 13b is applied to the S of the magnet 13b from the N pole of the magnet 13a. Magnetic field lines H parallel to the direction toward the pole are generated. Due to the magnetic force lines H, the tabular magnetic particles in the coating film 2 are oriented parallel to the magnetic force lines H.
As described above, the tabular magnetic particles in the coating film 2 can be oriented parallel to the magnetic field lines H.

(2) Orientation method B
FIG. 2 is a schematic configuration diagram showing an orientation device for performing the orientation method B in the method for producing a composite magnetic body of the present invention. The orientation device 21 is different from the orientation device 11 in FIG. This is in that the opposing poles of a pair of magnets 22a and 22b provided on the upper side and the lower side of the film 2 are arranged so as to have the same polarity.

In this orientation device 21, when a magnetic field is applied to the coating film 2 by a pair of magnets 22 a and 22 b, the magnetic lines of force generated from one magnet 22 a and the magnetic lines of force generated from the other magnet 22 b repel each other at the position of the coating film 2. Therefore, the lines of magnetic force H1 and H2 for applying a magnetic field parallel to the surface of the coating film 2 are generated. Due to the magnetic lines of force H1 and H2, the tabular magnetic particles in the coating film 2 are oriented in parallel to the magnetic lines of force H1 and H2.
As described above, the plate-like magnetic particles in the coating film 2 can be oriented in parallel to the magnetic lines of force H1 and H2.

(3) Orientation method C
FIG. 3 is a schematic configuration diagram showing an orientation device for performing the orientation method C in the method for producing a composite magnetic body of the present invention. The orientation device 31 is different from the orientation device 21 in FIG. A fixed interval, for example, so that the opposing poles of each of the pair of magnets 32a and 32b, the magnets 33a and 33b, and the magnets 34a and 34b provided on the upper side and the lower side of the film 2 are the same, respectively. It is the point arrange | positioned at the space | interval which the magnetic force lines of adjacent magnets do not cancel each other.

  For example, in the orientation device 21 shown in FIG. 2, the magnetic lines of force H1 and H2 generated from the N poles of the magnets 22a and 22b return to the S pole. Magnetic field lines that are perpendicular to the surface 2 and not parallel to the coating film 2 are also generated, and as a result, the orientation of the tabular magnetic particles may be lowered.

  On the other hand, in the orientation device 31 shown in FIG. 3, as shown in FIG. 4, before the coating film 2 passes between the pair of magnets 32a and 32b, the flat magnetic particles 41 in the coating film 2 have an orientation direction. Although it is in a disordered state, the tabular magnetic particles 41 in the coating film 2 are caused by the lines of magnetic force H1 and H2 generated parallel to the surface of the coating film 2 by passing between the magnets 32a and 32b. The tabular magnetic particles 41 are aligned along the magnetic field lines H1 and H2.

However, the orientation of the tabular magnetic particles 41 may be insufficient only by passing between the first magnets 32a and 32b. Therefore, by passing between the magnets 33a and 33b, the insufficient orientation of the tabular magnetic particles 41 is corrected and the orientation is improved. After passing between the last magnets 34a and 34b, the insufficient orientation of the tabular magnetic particles 41 is corrected and becomes highly oriented.
Thus, the orientation of the tabular magnetic particles 41 in the coating film 2 can be improved by applying the magnetic field to the coating film 2 a plurality of times.

(4) Orientation method D
FIG. 5 is a schematic configuration diagram showing an orientation device for performing the orientation method D in the method for producing a composite magnetic body of the present invention. The orientation device 51 is different from the orientation device 21 in FIG. A drying means 52 for pre-drying the coating film 2 is provided at a position where H1 and H2 are parallel to the tabular magnetic particles 41 in the coating film 2.

  The drying means 52 is not particularly limited as long as it has a drying function that can solidify the coating film 2, and examples thereof include a hot air blowing nozzle connected to a hot air supply source.

In this orientation device 51, when a magnetic field is applied to the coating film 2 by the pair of magnets 22a and 22b, magnetic lines H1 and H2 for applying a magnetic field parallel to the surface of the coating film 2 are generated, and these magnetic lines H1 and H2 are generated. Thus, the tabular magnetic particles in the coating film 2 are oriented parallel to the magnetic field lines H1 and H2. At this time, if the coating film 2 is preliminarily dried by the drying means 52, the orientation state of the plate-like magnetic particles oriented in parallel to the magnetic lines of force H1 and H2 can be fixed by solidifying the coating film 2.
As described above, the plate-like magnetic particles in the coating film 2 can be oriented in parallel to the magnetic lines of force H1 and H2.

As described above, the orientation of the tabular magnetic particles in the coating film 2 can be improved by performing only one of the orientation methods A to D alone or in combination of two or more. it can.
Even when the coating film 2 is replaced with a molded body having a predetermined shape, the orientation of the tabular magnetic particles in the molded body can be improved by appropriately applying one or more of the orientation methods A to D. it can.

  As said magnet 13a, 13b, ..., an electromagnet, a permanent magnet, etc. are mentioned. The arrangement of the magnets and the number of pairs are not particularly limited, and may be appropriately adjusted according to the shape of the coating film and the molded body and the required magnetic characteristics.

The magnitude of the magnetic field to be applied is preferably 100 gauss or more and 1000 gauss or less when different polarities such as those of the alignment apparatus shown in FIG. If the magnitude of the magnetic field is less than 100 gauss, the magnetic field is too small, and the flat magnetic particles in the compact may not be sufficiently oriented. On the other hand, if it exceeds 1000 gauss, the magnetic field is too large and the flat magnetic particles and the resin may be separated, resulting in non-uniformity in the magnetic properties of the obtained composite magnetic material.
Further, when the same poles as in the orientation device shown in FIG. 2 are faced to each other, separation between the tabular magnetic particles and the resin is difficult to occur, and therefore, it is preferably 100 gauss or more and 3000 gauss or less.

<Drying / curing>
The molded body in which the flat magnetic particles are oriented is dried, and then the resin is cured by heating or ultraviolet irradiation. The drying / curing conditions (processing temperature, processing time, etc.) may be appropriately adjusted according to the type of resin and solvent used.

[antenna]
The antenna of the present embodiment includes the above composite magnetic body.
As one form of this antenna, there is an antenna loaded with the above composite magnetic material.
The method for loading the antenna with the composite magnetic body is not particularly limited, and the conductor such as a copper wire constituting the antenna (hereinafter referred to as “antenna conductor”) is covered with the composite magnetic body. What is necessary is just to load by a well-known method.

The type and shape of the antenna are not particularly limited, and a monopole antenna, a loop antenna, a helical antenna, a patch antenna, an F-type antenna, an L-type antenna, or the like is preferably used. Further, a matching circuit may be used in combination in order to reduce the size of the antenna.
For example, a monopole antenna or an L-shaped antenna can be obtained by sandwiching the above composite magnetic body into a rod-like or long plate-like shape around the antenna conductor.
The helical antenna can be obtained by winding a long and extremely thin antenna conductor made of copper wire or the like in a coil shape around a rod-shaped composite magnetic material obtained by processing the above-described composite magnetic material into a rod shape.
With these antennas, it is possible to obtain a small antenna having a length shorter than ¼ of the desired wavelength due to the wavelength shortening effect.

FIG. 6 is a schematic diagram showing a method of feeding a monopole antenna which is an example of the antenna of the present embodiment. The monopole antenna 61 has a rod-shaped antenna conductor 62 and a surface of the antenna conductor 62 embedded by embedding the antenna conductor 62. And a plate-like composite magnetic body 63 covered with
The monopole antenna 61 is connected to a ground plane 64 made of a conductor having a predetermined shape via a coaxial connector or the like, and an AC signal transmitter 66 is used so that the connection portion 65 that is an inner conductor of the coaxial connector or the like serves as a feeding point. It is connected.
In the same manner as described above, the antenna is connected to the ground plane 64 via a connector or the like, and the AC signal transmitter 66 is connected so that the connecting portion 65 serves as a feeding point.

[Communication device]
The communication device of this embodiment includes the antenna described above.
The communication device is not particularly limited as long as it is a device that transmits, receives, or transmits / receives various information via electromagnetic waves. For example, personal computers, portable telephones, portable information terminals, multifunctional portable information terminals such as smartphones, communication devices such as PDAs (Personal Digital Assistants), various electronic devices such as audio devices, video devices, camera devices, etc. It is done.
In these communication devices, the antenna may be provided outside the communication device, or may be built in either.

Here, taking a portable telephone as an example of the communication device, various methods of attaching the antenna will be described.
FIG. 7 is a perspective view showing an example of a kind of mobile phone of the communication apparatus according to the present embodiment. The mobile phone 71 has a display function including a liquid crystal display, an organic EL display, or the like on the front surface of the housing 72. The display unit 73 is provided, and a ground plate (not shown) is provided on the back side of the display unit 73, and an antenna conductor 75 disposed in the rod-shaped monopole antenna 74 via a connector or the like is provided on the ground plate. The electronic circuit (not shown) of the portable telephone 71 is connected through this connection portion. The antenna conductor 75 of the monopole antenna 74 is covered with a composite magnetic body 76.

The monopole antenna 74 can be taken out from the casing 72 and can be stored in the casing 72. When communicating, the monopole antenna 74 is pulled out from the casing 72 as necessary to perform communication. When not communicating, the casing 72 It is designed to be pushed into the storage.
The monopole antenna 74 does not have to be rod-shaped and may be telescopic.
The monopole antenna 74 is preferably provided at a position that does not overlap the display unit 73 or the like in consideration of improving the antenna gain. In the case where the monopole antenna 74 is provided at a position overlapping with the display unit 73 and the like, it is preferable that the monopole antenna 74 and the display unit 73 are spaced from each other.

FIG. 8 is a perspective view showing another example of a kind of mobile phone of the communication apparatus of the present embodiment. The mobile phone 81 is a display comprising a liquid crystal display, an organic EL display, or the like on the front surface of the housing 82. A display portion 83 having a function is provided, and an external antenna terminal 84 is provided on the side surface. A connection terminal 86 provided on the side surface of the rod-shaped monopole antenna 85 is fitted into the external antenna terminal 84. The antenna conductor 87 disposed in the monopole antenna 85 is connected to a ground plate (not shown) provided on the back side of the display unit 83 via a connection terminal 86 and an external antenna terminal 84, and this connection The electronic circuit (not shown) of the portable telephone 81 is connected through the unit. In this monopole antenna 85, an antenna conductor 87 is covered with a composite magnetic body 88.
The portable telephone 81 can be attached and detached by inserting / removing the connection terminal 86 of the monopole antenna 85 to / from the external antenna terminal 84.

  FIG. 9 is a partial perspective view showing a part of still another example of a kind of mobile phone of the communication apparatus according to the present embodiment. The mobile phone 91 includes a liquid crystal display or an organic EL on the front surface of the housing 92. A ground plate 93 is provided on the back side of a display unit (not shown) having a display function such as a display, and an L-shaped antenna 94 is provided at a position that does not overlap the ground plate 93 (in FIG. 9, above the ground plate 93). An antenna conductor 95 made of a conductor such as a copper wire disposed in the L-shaped antenna 94 is connected to the ground plane 93 via a connector or the like, and an electronic circuit (not shown) of the portable telephone 91 is connected via this connection portion. Is connected. The L-shaped antenna 94 has an antenna conductor 95 covered with a composite magnetic body 96.

  FIG. 10 is a partial perspective view showing a part of still another example of a kind of mobile phone of the communication apparatus according to the present embodiment. The mobile phone 101 includes a liquid crystal display or an organic EL on the front surface of the housing 102. A ground plate 103 is provided on the back side of a display unit (not shown) having a display function such as a display, and a helical antenna 104 is provided at a position that does not overlap with the ground plate 103 (above the ground plate 103 in FIG. 10). A helical antenna conductor 106 wound around a rod-shaped composite magnetic body 105 of the helical antenna 104 is connected to the ground plate 103 via a connector or the like, and an electronic circuit (not shown) of the portable telephone 101 is connected via this connection portion. ) Is connected.

  According to each of the above examples, since the mounted monopole antennas 74 and 85, the L-shaped antenna 94 or the helical antenna 104 are both small, the antenna can be arranged in a narrow space in the portable phone, A portable telephone with a high antenna gain can be obtained without blocking radio waves by components other than the antenna.

As described above, according to the composite magnetic body of the present embodiment, since it contains a resin having a cyclic structure in the main chain and a functional group that is polymerized in monomer units, and flat magnetic particles. The effect of steric hindrance by the resin on the tabular magnetic particles can be reduced. Therefore, it is possible to provide a composite magnetic body having a high real part μr ′ of complex permeability and excellent mechanical strength.
In addition, since a resin having a functional group that is polymerized by monomer units is used, the bonding of the resin becomes strong, and it is possible to have mechanical strength as a molded body sufficient for use in electronic parts and the like.

According to the method for producing a composite magnetic body of the present embodiment, a resin having a cyclic structure in the main chain and a functional group that is polymerized in monomer units, tabular magnetic particles, and a curing agent and a solvent as necessary And obtaining a mixture, applying a magnetic field to the mixture to orient the tabular magnetic particles, and drying and curing the shaped body on which the tabular magnetic particles are oriented. A composite magnetic body having a high real part μr ′ of complex permeability and excellent mechanical strength can be easily produced.
Furthermore, the orientation of the flat magnetic particles in the coating film can be improved by applying a magnetic field to the coating film once or a plurality of times.

  According to the antenna of this embodiment, since the composite magnetic body of this embodiment is provided, a small antenna having a length shorter than ¼ of the desired wavelength can be obtained due to the wavelength shortening effect.

  According to the communication apparatus of the present embodiment, since the small antenna of the present embodiment is provided, the degree of freedom of placing the antenna in a place that is not easily affected by other electronic devices that block electromagnetic waves is high, and good transmission and reception are possible. A possible small communication device can be obtained.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.

In the examples and comparative examples, evaluation was performed by the following methods.
(1) Observation of tabular magnetic particles The particles were observed with a scanning electron microscope S-4000 (manufactured by Hitachi High-Tech).
(2) Measurement of real part μr ′ of complex permeability at 1 GHz Measurement was performed at 1 GHz at room temperature in the atmosphere using a permeability measuring device Vector Network Analyzer 8791ES (Agilent Technologies).
(3) Measurement of real part μr ′ of complex permeability at 200 MHz Permeability measurement apparatus Material analyzer E4991A type (manufactured by Agilent Technologies) was measured at 200 MHz at room temperature in the atmosphere.

[Example 1]
Dicyclopentadiene type epoxy resin EPICLON HP-7200L (manufactured by DIC Corporation), 1% by mass of 1-isobutyl-2-methylimidazole as a curing agent with respect to the total amount of epoxy resin and curing agent, resin and curing agent, The average major axis is 2.5 μm, the average thickness is 0.3 μm, and the average aspect ratio is 8 μm. The alloy is 30% by volume of Ni 75% by mass—Fe 20% by mass—Zn 5% by mass with respect to the total amount of the tabular magnetic particles. 3. Flat magnetic particles having a holding power of 35 oersted (Oe) and cyclohexanone were put into a planetary stirrer and mixed for 5 minutes to obtain a slurry-like mixture. The viscosity of this mixture was 4 Pa · S.

Next, the mixture was formed into a sheet on a polyethylene terephthalate (PET) film so as to have a thickness of 0.1 mm using a bar coater.
After forming the sheet, a 900 gauss magnetic field was applied to the surface of the sheet in the horizontal direction for 6 minutes. Subsequently, 80 degreeC warm air was applied and air-dried, and also hardening reaction was performed at 160 degreeC for 2 hours, and the composite magnetic body of Example 1 was obtained.

Using a scanning electron microscope (SEM), the angle formed by the long axis direction of the tabular magnetic particles with respect to the direction (orientation direction) horizontal to the sheet surface is measured using the scanning electron microscope (SEM). The inclination with respect to the horizontal direction was measured for 50 tabular magnetic particles. As a result, the average value of the 50 tilts was 8.2 degrees, and it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
In addition, μr ′ at room temperature and 1 GHz in the atmosphere of the composite magnetic material was 9.7.

[Example 2]
A composite magnetic body of Example 2 is obtained in the same manner as in Example 1 except that the content of the tabular magnetic particles is 40% by volume with respect to the total amount of the resin, the curing agent, and the tabular magnetic particles. It was.
When the inclination of the flat magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 flat magnetic particles in the same manner as in Example 1, the average value of the inclination was 8.5 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
Further, the complex magnetic permeability of this composite magnetic material was measured in the same manner as in Example 1. As a result, μr ′ at room temperature and 1 GHz in the atmosphere was 12.0.

[Example 3]
As a curing agent, instead of mixing 1% by mass of 1-isobutyl-2-methylimidazole with respect to the total amount of the epoxy resin and the curing agent, phenol novolac resin TD-2131 (manufactured by DIC Corporation) is added to the total amount of the epoxy resin. A composite magnetic body of Example 3 was obtained in the same manner as Example 1 except that equal amounts were mixed.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 1, the average value of the inclination was 8.6 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
Further, the complex permeability of this composite magnetic material was measured in the same manner as in Example 1. As a result, μr ′ at room temperature and 1 GHz in the atmosphere was 9.4.

[Example 4]
A composite magnetic body of Example 4 was obtained in the same manner as in Example 1 except that the magnetic field applied to the sheet in Example 1 was changed from 900 gauss to 700 gauss.
When the inclination of the flat magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 flat magnetic particles in the same manner as in Example 1, the average value of the inclination was 12.5 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
Further, the complex magnetic permeability of this composite magnetic material was measured in the same manner as in Example 1. As a result, μr ′ at room temperature and 1 GHz in the atmosphere was 8.4.

[Example 5]
A composite magnetic body of Example 5 was obtained in the same manner as in Example 1 except that the magnetic field applied to the sheet in Example 1 was changed from 900 gauss to 600 gauss.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the direction horizontal to the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 1, the average value of the inclination was 17.9 degrees. Thus, it was confirmed that the tabular magnetic particles were generally oriented in the horizontal direction on the sheet surface.
The complex magnetic permeability of this composite magnetic material was measured in the same manner as in Example 1. As a result, μr ′ at room temperature and 1 GHz in air was 7.2.

[Comparative Example 1]
Dicyclopentadiene type epoxy resin EPICLON HP-7200L (manufactured by DIC Corporation) was replaced with bisphenol type epoxy resin 1256 (manufactured by Mitsubishi Chemical Corporation) in the same manner as in Example 1, but the composite magnetic material of Comparative Example 1 Got.
When the inclination of the flat magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 flat magnetic particles in the same manner as in Example 1, the average value of the inclination was 21.5 degrees. These tabular magnetic particles were not aligned in one direction, and it was confirmed that the orientation was lowered.
Further, the complex permeability of this composite magnetic material was measured in the same manner as in Example 1. As a result, μr ′ at room temperature and 1 GHz in the atmosphere was 6.5.

[Comparative Example 2]
Dicyclopentadiene-type epoxy resin EPICLON HP-7200L (manufactured by DIC Corporation) was replaced with phenol novolac resin TD-2131 (manufactured by DIC Corporation) in the same manner as in Example 1, and the composite magnetic material of Comparative Example 2 Got.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 1, the average value of the inclination was 28.4 degrees. These tabular magnetic particles were not aligned in one direction, and it was confirmed that the orientation was lowered.
Further, the complex magnetic permeability of this composite magnetic material was measured in the same manner as in Example 1. As a result, μr ′ at room temperature and 1 GHz in the atmosphere was 5.8.

[Example 6]
Dicyclopentadiene type epoxy resin EPICLON HP-7200L (manufactured by DIC Corporation), 1% by mass of 1-isobutyl-2-methylimidazole as a curing agent with respect to the total amount of epoxy resin and curing agent, resin and curing agent, The average major axis is 2.5 μm, the average thickness is 0.3 μm, and the average aspect ratio is 8 μm. The alloy is 30% by volume of Ni 75% by mass—Fe 20% by mass—Zn 5% by mass with respect to the total amount of the tabular magnetic particles. 3. Flat magnetic particles having a holding power of 35 oersted (Oe) and cyclohexanone were put into a planetary stirrer and mixed for 5 minutes to obtain a slurry-like mixture. The viscosity of this mixture was 4 Pa · S.

Next, the mixture was formed into a sheet on a polyethylene terephthalate (PET) film so as to have a thickness of 0.1 mm using a bar coater.
After forming the sheet, the sheet was fed to the orientation device 11 shown in FIG. 1 at a speed of 2 m / min, and a magnetic field of 1200 gauss was applied. Subsequently, 80 degreeC warm air was applied and air-dried, and also hardening reaction was performed at 160 degreeC for 2 hours, and the composite magnetic body of Example 6 was obtained.

When the inclination with respect to the horizontal direction on the sheet surface of the tabular magnetic particles in this composite magnetic body was measured for 50 tabular magnetic particles in the same manner as in Example 1, the average value of the inclination was 8.2 degrees. In addition, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
In addition, in the atmosphere of this composite magnetic material, μr ′ at room temperature and 1 GHz was 9.7, and μr ′ at 200 MHz was 8.5.

[Example 7]
A composite magnetic body of Example 7 was obtained in the same manner as in Example 6 except that the content of the flat magnetic particles was 40% by volume with respect to the total amount of the resin and the curing agent.
When the inclination of the flat magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 flat magnetic particles in the same manner as in Example 1, the average value of the inclination was 8.5 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
The complex magnetic permeability of this composite magnetic material was measured in the same manner as in Example 6. As a result, μr ′ at 1 GHz in the air at room temperature was 12.0, and μr ′ at 200 MHz was 9.3.

[Example 8]
As a curing agent, instead of mixing 1% by mass of 1-isobutyl-2-methylimidazole with respect to the total amount of the epoxy resin and the curing agent, phenol novolac resin TD-2131 (manufactured by DIC Corporation) is added to the total amount of the epoxy resin. A composite magnetic body of Example 8 was obtained in the same manner as Example 6 except that equal amounts were mixed.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 1, the average value of the inclination was 8.6 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
The complex permeability of this composite magnetic material was measured in the same manner as in Example 6. As a result, μr ′ at room temperature and 1 GHz in the atmosphere was 9.4, and μr ′ at 200 MHz was 8.3.

[Example 9]
A composite magnetic body of Example 9 was obtained in the same manner as in Example 6 except that the magnetic field applied to the sheet in Example 6 was changed from 1200 gauss to 1000 gauss.
When the inclination of the flat magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 flat magnetic particles in the same manner as in Example 1, the average value of the inclination was 12.5 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
The complex permeability of this composite magnetic material was measured in the same manner as in Example 6. As a result, μr ′ at room temperature and 1 GHz in the atmosphere was 8.4, and μr ′ at 200 MHz was 7.7.

[Example 10]
A composite magnetic body of Example 10 was obtained in the same manner as in Example 1 except that the magnetic field applied to the sheet in Example 6 was changed from 1200 gauss to 900 gauss.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the direction horizontal to the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 1, the average value of the inclination was 17.9 degrees. Thus, it was confirmed that the tabular magnetic particles were generally oriented in the horizontal direction on the sheet surface.
The complex permeability of this composite magnetic material was measured in the same manner as in Example 6. As a result, μr ′ at room temperature and 1 GHz in air was 7.2, and μr ′ at 200 MHz was 7.2.

[Example 11]
In Example 7, after the sheet was formed, the composite of Example 11 was similarly obtained except that the sheet was fed to the orientation device 21 shown in FIG. 2 at a speed of 2 m / min and a magnetic field of 900 gauss was applied. A magnetic material was obtained.
When the inclination of the flat magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 flat magnetic particles in the same manner as in Example 1, the average value of the inclination was 16.4 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
In addition, this composite magnetic material had a μr ′ of 7.5 at 200 MHz in the air at room temperature.

[Example 12]
In Example 7, after forming the sheet, the composite of Example 12 was similarly obtained except that the sheet was fed to the orientation device 21 shown in FIG. 2 at a speed of 1 m / min and a magnetic field of 900 gauss was applied. A magnetic material was obtained.
When the inclination of the flat magnetic particles in the composite magnetic body with respect to the direction parallel to the sheet surface was measured for 50 flat magnetic particles in the same manner as in Example 1, the average value of the inclination was 17.0 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
In addition, μr ′ of this composite magnetic material in the atmosphere at room temperature and 200 MHz was 7.3.

[Example 13]
In Example 11, after forming the sheet, this sheet was fed to the orientation device 31 shown in FIG. 3 at a speed of 2 m / min, and a magnetic field of 300 gauss was applied to a pair of magnets. Subsequently, 80 degreeC warm air was applied and air-dried, and also hardening reaction was performed at 160 degreeC for 2 hours, and the composite magnetic body of Example 13 was obtained.
When the inclination of the tabular magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 tabular magnetic particles in the same manner as in Example 1, the average value of the inclination was 8.3 degrees. Thus, it was confirmed that the tabular magnetic particles were oriented in a direction substantially horizontal to the sheet surface, and the orientation was good.
Further, this composite magnetic body had a μr ′ of 9.0 at 200 MHz in the air at room temperature.

[Comparative Example 3]
Dicyclopentadiene type epoxy resin EPICLON HP-7200L (manufactured by DIC Corporation) was replaced with bisphenol type epoxy resin 1256 (manufactured by Mitsubishi Chemical Corporation) in the same manner as in Example 6, but the composite magnetic material of Comparative Example 3 Got.
When the inclination of the flat magnetic particles in the composite magnetic body with respect to the horizontal direction on the sheet surface was measured for 50 flat magnetic particles in the same manner as in Example 1, the average value of the inclination was 21.5 degrees. These tabular magnetic particles were not aligned in one direction, and it was confirmed that the orientation was lowered.
The complex permeability of this composite magnetic material was measured in the same manner as in Example 6. As a result, μr ′ at room temperature and 1 GHz in the atmosphere was 6.5, and μr ′ at 200 MHz was 5.6.

DESCRIPTION OF SYMBOLS 1 Base | substrate 2 Coating film 11 Orientation apparatus 12 Application | coating means 13a, 13b Magnet 14 Drying means 21 Orientation apparatus 22a, 22b Magnet 22 Magnet 31 Orientation apparatus 32a, 32b, 33a, 33b, 34a, 34b Magnet 41 Flat magnetic body particle 51 Orientation Device 52 Drying means 61 Monopole antenna 62 Antenna conductor 63 Composite magnetic body 64 Ground plate 65 Connection section 66 AC signal transmitter 71 Portable telephone 72 Case 73 Display section 74 Monopole antenna 75 Antenna conductor 76 Composite magnetic body 81 Portable telephone 82 Housing 83 Display unit 84 External antenna terminal 85 Monopole antenna 86 Connection terminal 87 Antenna conductor 88 Composite magnetic body 91 Portable telephone 92 Housing 93 Base plate 94 L-shaped antenna 95 Antenna conductor 96 Composite magnetic body 101 Portable telephone 102 Case 103 main plate 104 helical antenna 105 a composite magnetic body 106 antenna conductor 201 closed container 202 magnetic particles 203 slurry 204 dispersion medium 205 uniaxial rotator 205a outer circumferential edge H, H1, H2 field lines g traveling direction

Claims (10)

  A composite magnetic body comprising a resin having a cyclic structure in a main chain and a functional group that is polymerized in monomer units, and flat magnetic particles.   The composite magnetic body according to claim 1, wherein the resin is a thermosetting resin.   The composite magnetic body according to claim 1, wherein the resin is an epoxy resin.   4. The composite magnetic body according to claim 3, wherein the epoxy resin is a dicyclopentadiene type epoxy resin.   5. The angle between the orientation direction of the tabular magnetic particles in the resin and the major axis direction of the tabular magnetic particles is 20 ° or less, 5. Composite magnetic material.   The composite magnetic body according to claim 1, wherein a real part μr ′ of the complex magnetic permeability is 7 or more. A method for producing a composite magnetic body according to any one of claims 1 to 6,
A method for producing a composite magnetic material, comprising: a step of mixing a resin having a cyclic structure in a main chain and having a functional group that is polymerized in a monomer unit and flat magnetic particles to obtain a mixture.   After the step of obtaining the mixture, a molding step of molding the mixture into a predetermined shape, and an orientation in which a magnetic field is applied to the obtained molded body to orient the flat magnetic particles in the molded body in one direction. The method for producing a composite magnetic body according to claim 7, comprising a step and a drying / curing step of drying / curing the molded body.   An antenna comprising the composite magnetic body according to any one of claims 1 to 6.   A communication apparatus comprising the antenna according to claim 9.

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