JP2021181540A - Resin composition - Google Patents

Abstract

To provide a resin composition that has low viscosity at room temperature and can be used as magnetic paste.SOLUTION: A resin composition contains a thermosetting resin, a curing agent, a dispersant, and a magnetic filler. The content of the magnetic filler is 85 pts.mass or more relative to 100 pts.mass of the resin composition. The dispersant includes an amine wet dispersant. The resin composition has a viscosity of 400 Pa s or less at 25°C.SELECTED DRAWING: None

Description

The present disclosure relates generally to resin compositions, and more particularly to resin compositions containing magnetic fillers.

Patent Document 1 discloses a composite magnetic encapsulation material. This composite magnetic encapsulation material comprises a resin material and a filler. The filler is blended with the resin material, and the blending ratio is 30 to 85% by volume. Further, the filler contains a magnetic filler. This magnetic filler contains 32 to 39% by weight of a metal material containing Ni as a main component in Fe. As a result, the composite magnetic encapsulation material has a coefficient of thermal expansion of 15 ppm / ° C. or less.

Japanese Unexamined Patent Publication No. 2017-188646

However, the composite magnetic encapsulation material has a problem that it has a high viscosity at room temperature and is difficult to use as a magnetic paste.

An object of the present disclosure is to provide a resin composition which has a low viscosity at room temperature and can be used as a magnetic paste.

The resin composition according to one aspect of the present disclosure contains a thermosetting resin, a curing agent, a dispersant, and a magnetic filler. The content of the magnetic filler is 85 parts by mass or more with respect to 100 parts by mass of the resin composition. The dispersant contains an amine-based wet dispersant. The viscosity of the resin composition at 25 ° C. is 400 Pa · s or less.

The resin composition according to one aspect of the present disclosure contains a thermosetting resin, a dispersant, and a magnetic filler. The content of the thermosetting resin is 0.8 parts by mass or more with respect to 100 parts by mass of the resin composition. The dispersant contains an amine-based wet dispersant.

According to the present disclosure, it has a low viscosity at room temperature and can be used as a magnetic paste.

1. 1. First Embodiment (1) Outline The resin composition according to this embodiment contains a thermosetting resin, a curing agent, a dispersant, and a magnetic filler. The content of the magnetic filler is 85 parts by mass or more with respect to 100 parts by mass of the resin composition. As a result, the resin composition has magnetic properties. Further, the dispersant contains an amine-based wet dispersant. This makes it possible to reduce the viscosity of the resin composition at room temperature.

Therefore, the resin composition has a low viscosity at room temperature and can be used as a magnetic paste. In the present specification, "normal temperature" includes, for example, the temperature range (5 to 35 ° C.) specified in JIS Z 8703.

(2) Details <Resin composition>
The resin composition according to the present embodiment includes a filler and a resin material. More specifically, the resin composition contains a thermosetting resin, a curing agent, a dispersant, and a magnetic filler. The resin composition may further contain a solvent. The resin composition is, for example, a paste. The viscosity of the resin composition at 25 ° C. is 400 Pa · s or less, preferably 200 Pa · s or less. Thereby, the coatability and the printability can be improved.

≪Filler≫
The filler contains a magnetic filler. The magnetic filler is a powdery substance that can be magnetized. As described above, when the filler contains the magnetic filler, a molded product having magnetic properties can be obtained. Magnetic properties are magnetic properties that are exhibited when magnetized. Specific examples of the magnetic characteristics include magnetic permeability and magnetic flux density.

As described above, the molded product has magnetic properties, but the molded product according to the present embodiment can have a high magnetic permeability at a high frequency. The high frequency frequency band is, for example, in the range of several tens of MHz or more and several GHz or less, and includes 100 MHz. Permeability, in particular, refers to the complex relative permeability (μ _r). The complex relative permeability (μ _r ) is _{expressed by the formula μ r} = μ / μ ₀ (μ: complex permeability, μ ₀ : vacuum permeability). The complex magnetic permeability (μ) is expressed by the formula μ = μ'−iμ ”(μ': real part, μ”: imaginary part, i: imaginary unit).

The filler may further contain a non-magnetic filler. The non-magnetic filler is a non-magnetic powdery substance.

The content of the filler is preferably in the range of 30% by volume or more and 85% by volume or less, and more preferably 40% by volume or more and 75% by volume or less with respect to the total volume of the resin composition. When the content of the filler is 30% by volume or more, the magnetic permeability at high frequency can be further increased. When the content of the filler is 85% by volume or less, the machinability can be improved. In particular, the hole workability can be improved.

[Magnetic filler]
Magnetic fillers include iron-nickel alloy fillers. The iron-nickel alloy filler is a magnetic filler made of an iron-nickel alloy. An iron-nickel alloy is a eutectic containing an iron element and a nickel element. The eutectic of the iron-nickel alloy may further contain an element of molybdenum.

The nickel content is more than 39% by mass, preferably 45% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, based on the total mass of the iron-nickel alloy filler. be.

As described above, since the nickel content is higher than that of the conventional iron-nickel alloy filler, the chemical resistance of the molded product is improved. Here, the chemical resistance is a property that the molded product is not significantly deteriorated by the treatment of chemicals. The chemical treatment is not particularly limited, and examples thereof include desmear treatment, electroless plating, and electrolytic plating. Examples of the chemicals include chemicals for desmear treatment (chromic acid, sulfuric acid, neutralizers, conditioners, hydrofluoric acid, etc.), chemicals for electroless plating treatment, and plating solutions for electrolytic plating. The chemicals also include chemicals used for pre- and post-plating treatments. For example, acids such as sulfuric acid used in pretreatments for electroless plating (soft etching, pickling, predip, etc.) are also included.

When the chemical resistance of the molded product is increased, the performance of the molded product after being treated with the chemical can easily maintain the performance of the molded product before being treated with the chemical. That is, even if the molded product having magnetic properties is exposed to chemicals, the molded product can maintain the magnetic properties before being exposed to the chemicals. As described above, the molded product according to the present embodiment does not easily deteriorate in magnetic properties even when treated with chemicals.

Further, since the nickel content is higher than that of the conventional iron-nickel alloy filler, the machinability of the molded product is improved. Here, the machinability is a degree indicating the ease of machining of a molded product. The machinability is not particularly limited, and examples thereof include hole machinability. The hole workability is a degree indicating the ease of processing the molded body when drilling a through hole in the molded body. The hole workability can be evaluated, for example, by the degree of wear of the drill bit.

When the machinability of the molded body, particularly the hole workability, is improved, for example, wear of the drill bit, unevenness of the hole wall, and generation of smear are reduced.

The upper limit of the nickel content with respect to the total mass of the iron-nickel alloy filler is not particularly limited, but is preferably 90% by mass or less, more preferably 85% by mass or less.

In the present embodiment, the content of the magnetic filler is 85 parts by mass or more with respect to 100 parts by mass of the resin composition. This makes it possible to further increase the magnetic permeability at high frequencies. Preferably, the content of the magnetic filler is 98 parts by mass or less with respect to 100 parts by mass of the resin composition. This makes it possible to improve machinability. In particular, the hole workability can be improved.

The average particle size of the magnetic filler (for example, iron-nickel alloy filler) is preferably 5 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less. Here, the average particle size means the particle size at an integrated value of 50% in the particle size distribution measured based on the particle size distribution measuring device based on the laser scattering / diffraction method, that is, the 50% volume average particle size (D50). As described above, by reducing the average particle size of the magnetic filler (for example, iron-nickel alloy filler), the eddy current loss is mainly reduced, and the magnetic loss at high frequencies can be reduced. Specifically, the loss coefficient (tan δ) can be reduced. The loss coefficient (tan δ) is expressed by the formula tan δ = μ ”/ μ’.

The iron-nickel alloy filler preferably contains spherical particles. This makes it possible to increase the filling of the iron-nickel alloy filler. That is, when the iron-nickel alloy filler contains spherical particles, the filling amount of the iron-nickel alloy filler in the magnetic filler can be increased as compared with the case where the iron-nickel alloy filler does not contain spherical particles. The iron-nickel alloy filler may contain particles having a shape other than the spherical shape. The shape other than the spherical shape is not particularly limited, and examples thereof include an ellipsoidal shape, a flat shape, a crushed shape, and an indefinite shape.

As described above, when the iron-nickel alloy filler is highly filled, it is possible to increase the magnetic permeability of the molded product even if the average particle size of the iron-nickel alloy filler is small. Further, the fluidity of the resin composition can be improved. That is, it becomes easy to mold the molded body.

Here, the case where the surface of the iron-nickel alloy filler is covered with the insulating layer (first case) and the case where the surface of the iron-nickel alloy filler is not covered with the insulating layer (second case). By comparison, the first case is preferable. That is, preferably, the surface of the iron-nickel alloy filler is covered with an insulating layer. More specifically, the surface of the individual particles constituting the iron-nickel alloy filler is coated with an insulating layer. In the second case, it is considered that the individual particles come into contact with each other and behave as a large mass of particles, but in the first case, the contact of the individual particles is suppressed by the insulating layer. Therefore, the insulating layer can suppress the generation of eddy currents flowing between the particles of the adjacent iron-nickel alloy filler. By reducing the eddy current loss in this way, the magnetic loss can be reduced.

The magnetic filler preferably further contains ferrite. Ferrite is a ceramic filler containing iron oxide as a main component. By further containing ferrite in the magnetic filler, the magnetic permeability at high frequencies can be further increased.

Ferrites include soft ferrites exhibiting soft magnetism and hard ferrites exhibiting hard magnetism. Ferrites are classified into spinel ferrites, hexagonal ferrites, garnet ferrites, and the like according to their crystal structures.

Spinel ferrite has a spinel-type crystal structure. The composition formula of spinel ferrite is represented by AFe ₂ O ₄ (A is Mn, Co, Ni, Cu, Zn, etc.). Most of the spinel ferrites are soft ferrites. Spinel ferrite includes, for example, manganese-zinc ferrite, nickel-zinc ferrite, copper-zinc ferrite and the like. Since spinel ferrite has high magnetic permeability and electrical resistance, the eddy current loss in the high frequency frequency band is small. Magnetite is also a type of spinel ferrite. The composition formula of magnetite is represented by _{Fe 3} O _4.

Hexagonal ferrite has a magnetoplumbite-type hexagonal crystal structure. The composition formula of hexagonal ferrite is represented by AFe ₁₂ O ₁₉ (A is Ba, Sr, Pb, etc.). Hexagonal ferrite is also called magnetoplambite-type ferrite or M-type ferrite. Hexagonal ferrite has a larger magnetic anisotropy than spinel ferrite, so it exhibits a large coercive force. Hexagonal ferrite is a typical hard ferrite.

Garnet ferrite has a garnet-type crystal structure. The composition formula of garnet ferrite is _{represented by RFe 5} O ₁₂ (R is a rare earth element). Garnet ferrite is also called Rare-earth Iron Garnet (RIG). A typical example of garnet ferrite is yttrium iron garnet (YIG). Garnet ferrite has a small magnetic loss at high frequencies.

When the magnetic filler further contains ferrite, the average particle size of the ferrite is preferably smaller than the average particle size of the iron-nickel alloy filler. As a result, the gaps between the particles of the iron-nickel alloy filler can be filled with ferrite. If there is a gap between the particles of the iron-nickel alloy filler, a demagnetic field can be generated in this gap. This demagnetic field can cause a decrease in magnetic permeability, but if the above gap is filled with ferrite, the magnetic permeability at high frequencies can be further increased.

If the magnetic filler further comprises ferrite, the ferrite preferably comprises spherical particles. This makes it possible to increase the filling of ferrite. That is, when the ferrite contains spherical particles, the filling amount of ferrite in the magnetic filler can be increased as compared with the case where the ferrite does not contain spherical particles. The ferrite may contain particles having a shape other than the spherical shape. The shape other than the spherical shape is not particularly limited, and examples thereof include an ellipsoidal shape, a flat shape, a crushed shape, and an indefinite shape.

As described above, when the ferrite is highly filled, it is possible to increase the magnetic permeability of the molded product. Further, the fluidity of the resin composition can be improved. That is, it becomes easy to mold the molded body.

When the magnetic filler further contains ferrite, the content of ferrite is preferably 0.1 part by mass or more and 35 parts by mass or less, more preferably 1 part by mass with respect to 100 parts by mass of the total of the iron-nickel alloy filler and the ferrite. It is within the range of 20 parts by mass or less. When the ferrite content is 0.1 part by mass or more, the magnetic permeability at high frequencies can be further increased. When the ferrite content is 35 parts by mass or less, the thickening of the resin composition can be suppressed.

[Non-magnetic filler]
The non-magnetic filler is not particularly limited, and examples thereof include silica powder and alumina powder.

The silica powder may contain crystalline silica particles, amorphous silica particles, and the like.

The alumina powder may contain α-alumina particles, γ-alumina particles, δ-alumina particles, θ-alumina particles, η-alumina particles, κ-alumina particles and the like.

≪Resin material≫
Resin materials include, for example, thermosetting resins, curing agents, curing accelerators, surface treatment agents and the like.

[Thermosetting resin]
The thermosetting resin is not particularly limited, and examples thereof include a bisphenol F type epoxy resin, a reactive diluent, a glycidylamine type epoxy resin, an alicyclic epoxy resin, and a bisphenol A type epoxy resin.

Preferably, the thermosetting resin contains a bisphenol F type epoxy resin. When the thermosetting resin contains a bisphenol F type epoxy resin, the content of the bisphenol F type epoxy resin is preferably 15% by mass or more with respect to the total mass of the thermosetting resin. This makes it possible to further reduce the viscosity of the resin composition. The content of the bisphenol F type epoxy resin is preferably 35% by mass or less with respect to the total mass of the thermosetting resin.

Reactive diluents include alkyl diglycidyl ethers, alkyl monoglycidyl ethers, alkylphenol monoglycidyl ethers and the like. When the reactive diluent is contained in the resin composition together with the other epoxy resin, the viscosity of the resin composition can be reduced without impairing the characteristics of the other epoxy resin.

Preferably, the thermosetting resin contains a glycidylamine type epoxy resin. The glycidylamine type epoxy resin includes a polyfunctional amine type epoxy resin. Since the glycidylamine type epoxy resin is polyfunctional, it is highly reactive. Therefore, when the glycidylamine type epoxy resin is contained in the resin composition, the crosslink density of the cured product becomes high, the cured product exhibits tough physical properties, and exhibits excellent performance in heat resistance and chemical resistance.

Preferably, the thermosetting resin is liquid. When the thermosetting resin is liquid, it is easy to make the resin composition into a paste. The reactive diluent is effective in reducing the viscosity of the resin composition.

When the thermosetting resin contains an epoxy resin, the epoxy equivalent of the epoxy resin is not particularly limited, but is, for example, in the range of 90 g / eq or more and 200 g / eq or less.

When the thermosetting resin contains an alicyclic epoxy resin, the content of the alicyclic epoxy resin is preferably 30% by mass or more, more preferably 55% by mass or more, based on the total mass of the thermosetting resin. More preferably, it is 80% by mass or more. This makes it possible to further reduce the viscosity of the resin composition.

[Curing agent]
The curing agent is not particularly limited, and examples thereof include acid anhydrides, phenols, polyamines, polyamides, and imidazole compounds. Acid anhydrides include methylbicyclo [2.2.1] heptane-2,3-dicarboxylic acid anhydride and bicyclo [2.2.1] heptane-2,3-dicarboxylic acid anhydride. Preferably, the curing agent is liquid. If the curing agent is liquid, it is easy to make the resin composition into a paste. When the curing agent contains acid anhydrides, the acid anhydride equivalent of the acid anhydrides is, for example, in the range of 170 or more and 190 or less. The imidazole compound is effective for storage stability and low viscosity of the resin composition. In addition, some curing agents can function as a curing accelerator.

Preferably, the content of the curing agent is 4.2 parts by mass or more with respect to 100 parts by mass of the resin composition. As a result, the resin composition has a low viscosity at room temperature and can be used as a magnetic paste.

[Hardening accelerator]
The curing accelerator is not particularly limited, and examples thereof include an imidazole compound and the like. Preferably, the curing accelerator is encapsulated. If the curing accelerator is encapsulated, the storage stability of the resin composition can be improved. Further, by changing the film thickness of the capsule, the curing start temperature of the resin composition can be controlled, and the curing behavior can be adjusted according to the usage pattern. For example, if the film thickness of the capsule is reduced, the reaction can be started at a low temperature. On the other hand, if the film thickness of the capsule is increased, the reaction can be started at a high temperature and the storage stability at a low temperature and a normal temperature can be improved. In addition, some curing accelerators may function as a curing agent.

[Surface treatment agent]
Surface treatment agents are used to form an interface between a filler surface with different chemical properties and a resin material. The surface treatment agent is not particularly limited, and examples thereof include a silane coupling agent and a dispersant. The silane coupling agent and the dispersant can improve the dispersibility of the filler in the resin composition.

In this embodiment, the dispersant contains an amine-based wet dispersant. The amine-based wet dispersant can promote the dispersion of the filler (particularly the magnetic filler) in the resin composition. The amine-based wet dispersant is a compound having both an amino group and a compatible chain. Amino groups can be adsorbed on the filler. The compatible chain can be compatible with the resin material. When the amino group is adsorbed on the filler and the compatible chain is compatible with the resin material, the viscosity of the resin composition is reduced and long-term storage stability is obtained. As described above, the amine-based wet dispersant can uniformly disperse the filler in the thermosetting resin and the curing agent. The amine-based wet dispersant can suppress the aggregation and sedimentation of the filler. The amine value of the amine-based wet dispersant is preferably 40 mgKOH / g or more and 50 mgKOH / g or less.

Commercially available amine-based wet dispersants include, for example, the trade names "DISPERBYK-2152", "DISPERBYK-2155", "DISPERBYK-2157", "DISPERBYK-180", "BYK-9076" and "BYK-9077" may be mentioned.

Preferably, the content of the dispersant is 2 parts by mass or less with respect to 100 parts by mass of the magnetic filler. This makes it possible to further reduce the viscosity of the resin composition.

≪Solvent≫
The solvent is not particularly limited, and examples thereof include methyl ethyl ketone (MEK), N, N-dimethylformamide (DMF), acetone, and methyl isobutyl ketone (MIBK).

<Molded body>
The molded body according to the present embodiment is formed by molding a resin composition. Therefore, the molded product has high chemical resistance, and its magnetic properties are unlikely to deteriorate even when exposed to chemicals.

When the resin material contains a thermosetting resin, the molded product is obtained by heat-curing the resin composition. The molded product has the following magnetic properties.

That is, the real part (μ') of the complex magnetic permeability of the molded product at 100 MHz is preferably 6 or more, more preferably 8 or more. This makes it possible to further increase the magnetic permeability at high frequencies.

The loss coefficient (tan δ) of the molded product at 100 MHz is preferably 0.1 or less, more preferably 0.08 or less. This makes it possible to further reduce the loss.

The molded body can form a part of an insulating substrate used for manufacturing a printed wiring board. Even if the insulating substrate is treated with chemicals, the chemical resistance of the molded product is high, so that the magnetic properties of the molded product can be maintained. Therefore, it is possible to impart the magnetic characteristics of the molded product to the printed wiring board.

Further, the molded body may be used for manufacturing an inductor component. The inductor component includes a coiled wiring and an insulating layer covering the coiled wiring. The insulating layer is the above-mentioned molded product. This makes it easier for the inductor component to control noise in the high frequency band. Inductor components include coils, inductors, filters, reactors, and transformers. The use of the inductor component is not particularly limited, and examples thereof include a noise filter component and an impedance matching circuit component. Examples of the noise filter include a low-pass filter and a common choke coil.

2. 2. Second Embodiment (1) Outline The resin composition according to this embodiment contains a thermosetting resin, a dispersant, and a magnetic filler. As a result, the resin composition has magnetic properties. The content of the thermosetting resin is 0.8 parts by mass or more with respect to 100 parts by mass of the resin composition. Further, the dispersant contains an amine-based wet dispersant. This makes it possible to reduce the viscosity of the resin composition at room temperature.

Therefore, it has a low viscosity at room temperature and can be used as a magnetic paste.

(2) Details In the present embodiment, detailed description of the same components as those in the first embodiment may be omitted.

<Resin composition>
In the present embodiment, the viscosity of the resin composition at 25 ° C. is preferably 400 Pa · s or less, more preferably 200 Pa · s or less. Thereby, the coatability and the printability can be improved.

≪Filler≫
The filler of the present embodiment is the same as the filler of the first embodiment. That is, also in this embodiment, the average particle size of the magnetic filler (for example, iron-nickel alloy filler) is preferably 5 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less. As described above, by reducing the average particle size of the magnetic filler (for example, iron-nickel alloy filler), the eddy current loss is mainly reduced, and the magnetic loss at high frequencies can be reduced. Specifically, the loss coefficient (tan δ) can be reduced.

≪Resin material≫
The resin material of the present embodiment includes, for example, a thermosetting resin, a surface treatment agent, and the like. However, the resin material of the present embodiment does not have to contain a curing agent (particularly acid anhydrides).

In the present embodiment, the content of the thermosetting resin is 0.8 parts by mass or more with respect to 100 parts by mass of the resin composition. As a result, the resin composition has a low viscosity at room temperature and can be used as a magnetic paste.

The amine-based wet dispersant of the present embodiment is the same as the amine-based wet dispersant of the first embodiment. Also in this embodiment, the filler can be uniformly dispersed in the thermosetting resin by the amine-based wet dispersant. The amine-based wet dispersant can suppress the aggregation and sedimentation of the filler. The amine value of the amine-based wet dispersant is preferably 40 mgKOH / g or more and 50 mgKOH / g or less.

Also in this embodiment, the content of the dispersant is preferably 2 parts by mass or less with respect to 100 parts by mass of the magnetic filler. This makes it possible to further reduce the viscosity of the resin composition.

3. 3. Aspects As will be clear from the above embodiments, the present disclosure includes the following aspects.

The first aspect is a resin composition containing a thermosetting resin, a curing agent, a dispersant, and a magnetic filler. The content of the magnetic filler is 85 parts by mass or more with respect to 100 parts by mass of the resin composition. The dispersant contains an amine-based wet dispersant. The viscosity of the resin composition at 25 ° C. is 400 Pa · s or less.

According to this aspect, the viscosity at room temperature is low and the paste can be used as a magnetic paste.

The second aspect is a resin composition containing a thermosetting resin, a dispersant, and a magnetic filler. The content of the thermosetting resin is 0.8 parts by mass or more with respect to 100 parts by mass of the resin composition. The dispersant contains an amine-based wet dispersant.

According to this aspect, the viscosity at room temperature is low and the paste can be used as a magnetic paste.

The third aspect is the resin composition based on the first or second aspect. In the third aspect, the thermosetting resin contains a glycidylamine type epoxy resin.

According to this aspect, the crosslink density of the cured product is increased, the cured product exhibits tough physical properties, and exhibits excellent performance in heat resistance and chemical resistance.

The fourth aspect is a resin composition based on any one of the first to third aspects. In the fourth aspect, the thermosetting resin contains a bisphenol F type epoxy resin.

According to this aspect, the viscosity of the resin composition can be further reduced.

A fifth aspect is a resin composition based on the fourth aspect. In the fifth aspect, the content of the bisphenol F type epoxy resin is 15% by mass or more with respect to the total mass of the thermosetting resin.

According to this aspect, the viscosity of the resin composition can be further reduced.

The sixth aspect is a resin composition based on any one of the first to fifth aspects. In the sixth aspect, the content of the dispersant is 2 parts by mass or less with respect to 100 parts by mass of the magnetic filler.

According to this aspect, the viscosity of the resin composition can be further reduced.

A seventh aspect is a resin composition based on any one of the first to sixth aspects. In the seventh aspect, the magnetic filler contains a filler having an average particle size of 5 μm or less.

According to this aspect, the magnetic loss at high frequency can be reduced.

The eighth aspect is a resin composition based on any one of the first to seventh aspects. In the eighth aspect, the viscosity of the resin composition at 25 ° C. is 200 Pa · s or less.

According to this aspect, the coatability and printability can be improved.

Hereinafter, the present disclosure will be specifically described with reference to Examples. However, the present disclosure is not limited to the examples.

A resin composition (hereinafter, also referred to as “magnetic paste”) was prepared. The raw materials for the magnetic paste are shown below.

≪Filler≫
[Fe-Ni alloy]
Fe-50Ni (1) (nickel content: 50% by mass, average particle size: 3 μm, particle shape: spherical, insulating layer: present)
Fe-50Ni (2) (nickel content: 50% by mass, average particle size: 3 μm, particle shape: spherical, insulating layer: none)
[Ferrite]
-Magnetite (average particle size: 0.3 μm, insulating layer: none)
≪Resin material≫
[Thermosetting resin]
-Bisphenol F type epoxy resin (Nittetsu Chemical & Materials Co., Ltd., trade name "YDF-8170C", liquid, epoxy equivalent: 155 to 165 g / eq)
-Reactive diluent (Mitsubishi Chemical Corporation, trade name "YED216D", alkyl diglycidyl ether, liquid, epoxy equivalent: 110-130 g / eq)
Glysidylamine type epoxy resin (Nittetsu Chemical & Materials Co., Ltd., trade name "YH-523", trifunctional polyglycidylamine, liquid, epoxy equivalent: 92-100 g / eq)
-Alicyclic epoxy resin (Daicel Co., Ltd., trade name "Selokiside 2021P", liquid, epoxy equivalent: 128 to 145 g / eq)
[Curing agent]
-Epoxy resin curing agent (New Japan Rika Co., Ltd., trade name "Ricacid HNA-100", acid anhydride, acid anhydride equivalent: 174 to 184)
[Hardening accelerator]
-Epoxy resin latent curing agent (Asahi Kasei Corporation, trade name "NovaCure HX-3722", capsule-type latent curing agent)
・ Imidazole epoxy resin curing agent (Shikoku Kasei Kogyo Co., Ltd., trade name "2MAOK-PW", fine powder)
[Surface treatment agent]
・ Silane coupling agent (Momentive Performance Materials Japan GK, product name "Silquest A-187")
Amine-based 1: Amine-based wet dispersant (Big Chemie Japan Co., Ltd., trade name "DISPERBYK-2155", amine value: 48 mgKOH / g)
-Amine-based 2: Amine-based wet dispersant (Big Chemie Japan Co., Ltd., trade name "BYK-9077", amine value: 48 mgKOH / g)
<Magnetic paste>
The above raw materials were blended so as to have the contents shown in Table 1 and mixed uniformly to obtain a magnetic paste. A known mixer was used for mixing the raw materials.

<Evaluation>
The above magnetic paste was tested for the following evaluation items.

[viscosity]
The viscosity of the magnetic paste was measured using a rheometer "AR2000ex" manufactured by TA Instruments. Specifically, the gap between the upper and lower parallel plates having a diameter of 25 mm is set to 300 μm, and after filling this gap with a magnetic paste, a temperature equilibrium time of 2 minutes is allowed at room temperature (25 ° C.), and the number of rotations is increased. Viscosity was measured at 2.0 rpm.

[Chixo index]
In the same manner as the above viscosity measurement, the viscosity of the magnetic paste was measured at a rotation speed of 0.2 rpm. The chixo index of the magnetic paste was calculated by the following formula using the viscosity at a rotation speed of 0.2 rpm and the viscosity at a rotation speed of 2.0 rpm.

Chixo index = Viscosity at 0.2 rpm / Viscosity at 2.0 rpm [Magnetic characteristics]
The magnetic paste was heat-cured in the atmosphere to obtain a ring-shaped evaluation molded product (outer diameter 7.0 mm, inner diameter 3.5 mm, thickness 1.0 mmt). The heating conditions are 100 ° C. for 1 hour and then 150 ° C. for 1 hour.

Next, the complex magnetic permeability of the ring-shaped evaluation molded product at 100 MHz was measured using a “4291A RF impedance / material analyzer” manufactured by Hewlett-Packard Company. The measurement was performed at room temperature with the current frequency in the range of 1 MHz or more and 1.8 GHz or less. From initial magnetization curve obtained by measuring the real part (mu '), the imaginary part to obtain a (mu "), these were calculated permeability (complex permeability (mu _r)) and loss factor (tan [delta) ..

Claims (8)

A resin composition containing a thermosetting resin, a curing agent, a dispersant, and a magnetic filler.
The content of the magnetic filler is 85 parts by mass or more with respect to 100 parts by mass of the resin composition.
The dispersant contains an amine-based wet dispersant and contains
The viscosity of the resin composition at 25 ° C. is 400 Pa · s or less.
Resin composition. A resin composition containing a thermosetting resin, a dispersant, and a magnetic filler.
The content of the thermosetting resin is 0.8 parts by mass or more with respect to 100 parts by mass of the resin composition.
The dispersant comprises an amine-based wet dispersant.
Resin composition. The thermosetting resin contains a glycidylamine type epoxy resin.
The resin composition according to claim 1 or 2. The thermosetting resin contains a bisphenol F type epoxy resin.
The resin composition according to any one of claims 1 to 3. The content of the bisphenol F type epoxy resin is 15% by mass or more with respect to the total mass of the thermosetting resin.
The resin composition according to claim 4. The content of the dispersant is 2 parts by mass or less with respect to 100 parts by mass of the magnetic filler.
The resin composition according to any one of claims 1 to 5. The magnetic filler contains a filler having an average particle diameter of 5 μm or less.
The resin composition according to any one of claims 1 to 6. The viscosity of the resin composition at 25 ° C. is 200 Pa · s or less.
The resin composition according to any one of claims 1 to 7.