JP2022143652A - Method for manufacturing composite magnetic thermosetting molding - Google Patents

Abstract

To provide a method for manufacturing a composite magnetic thermosetting molding using a composite magnetic material which is powdery having flowability when supplied to a mold, and is liquid having flowability when compressed during thermal molding.SOLUTION: A method for manufacturing a composite magnetic thermosetting molding includes: a material preparation step of mixing metal magnetic powder, a thermosetting resin and a high melting point compound having a melting point of 25°C or higher and lower than 100°C and a boiling point of 160°C or higher so that a mass of the high melting point compound is 3.0 wt.% or more and 100 wt.% or less with respect to the mass of the thermosetting resin, to obtain a powdery composite magnetic material; a compression molding step of supplying the composite magnetic material to a mold adjusted to 100°C or higher into a liquid state, and subjecting the liquid composite magnetic material to compression molding by a molding pressure of 1,000 kgf/cm2 or less to obtain a composite magnetic molding; and a thermosetting step of heating the composite magnetic molding, and thermosetting a thermosetting resin while volatilizing and removing the high melting point compound to obtain a composite magnetic thermosetting molding.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a composite magnetic thermosetting molding.

Various types of coil components are known for use in electronic devices. Among them, coil components are formed by integrally molding a magnetic core material composed of a composite magnetic material in which metal magnetic powder is dispersed in a binder resin, and a coil or coil assembly. Many coil parts are used. For example, in Patent Document 1, a winding coil is enclosed in a powder magnetic body composed of a mixture containing soft magnetic powder and a binder, and pressed at a molding pressure of 4.5 to 10.0 ton/cm ² A molded integrated inductance component (coil component) is described.

Japanese Patent Application Laid-Open No. 2006-319020

By the way, in recent years, as a method of molding a metal inductor such as a coil component using a composite magnetic material, there has been an increase in the use of thermoforming in which a metal mold is heated and then compression-molded. In this thermoforming, the composite magnetic material can be softened by heating, so that molding can be performed at a lower pressure, and the reliability of the obtained metal inductor can be increased and the cost can be reduced.

In the case of thermoforming, the practically desirable properties of the composite magnetic material are powders that have fluidity when supplied to the mold, from the viewpoint of both ease of feeding into the mold and ease of thermoforming. It is in the form of a fluid, and becomes liquid when compressed in thermoforming. Until now, studies have been made to obtain the above properties depending on the characteristics of the thermosetting resin used, but there are cases where it is difficult to achieve the above properties only with the characteristics of the thermosetting resin, and further improvements are needed. There was room.

The present invention has been made in view of the above-mentioned problems, and a composite magnetic material using a composite magnetic material that becomes powdery with fluidity when supplied to a mold and becomes liquid with fluidity when compressed in thermoforming. An object of the present invention is to provide a method for producing a thermosetting molding.

In order to solve the above-mentioned problems, the present inventors have made intensive studies and found that the composite magnetic material contains a predetermined amount of a predetermined high-melting point compound. The composite magnetic material can be made into a liquid state with fluidity when compressed, and by using this composite magnetic material, the composite magnetic thermosetting molded body can be easily fed into a mold and heat-molded. The inventors have found that a manufacturing method can be provided, and completed the present invention.

That is, the present invention is a method for manufacturing a composite magnetic thermosetting molding comprising a material preparation step, a compression molding step, and a thermosetting step, wherein the material preparation step comprises a metal magnetic powder and a thermosetting resin. and a high melting point compound having a melting point of 25° C. or more and less than 100° C. and a boiling point of 160° C. or more, and a mass of the high melting point compound of 3.0 wt % or more and 100 wt % or less with respect to the mass of the thermosetting resin. In the compression molding step, the composite magnetic material is supplied to a mold adjusted to 100 ° C. or higher to make it liquid, and the pressure is 1000 kgf / cm ^2. A process of obtaining a composite magnetic molded body by compression molding with a molding pressure of 2 or less. is heat-cured to obtain a composite magnetic thermoset molding.

According to the present invention, it is possible to provide a method for manufacturing a composite magnetic thermosetting molding that facilitates both supplying a composite magnetic material to a mold and thermoforming.

FIG. 2 is a process diagram (process cross-sectional view) showing an example of a method for manufacturing a composite magnetic thermosetting molded body (a composite magnetic thermosetting molded body containing a coil) according to the present embodiment. 4 is a photograph showing the properties of the composite magnetic material produced in Example 1 at room temperature and after heating (100° C.) (photograph substituting for drawing). The upper part shows the composite magnetic material that does not contain the prescribed high-melting point compound, and the lower part shows the composite magnetic material that contains the prescribed high-melting point compound.

Embodiments of the present invention will be described below.

In the method of manufacturing a composite magnetic thermosetting molding according to the present embodiment, a composite magnetic material composed of metal magnetic powder, thermosetting resin, and a predetermined high melting point compound is obtained in the material preparation process. That is, a composite magnetic material containing at least a metal magnetic powder, a thermosetting resin, and a predetermined high-melting point compound as main components (90 wt % or more, more preferably 95 wt % or more in total) is obtained.
First, each material constituting this composite magnetic material will be described in detail.

<Metal magnetic powder>
A metal magnetic powder is a magnetic powder that can be obtained by a method of pulverizing a metal magnetic material, and contains iron as a main component. As the metal magnetic material, for example, iron, an alloy containing iron (iron-silicon, iron-aluminum-silicon alloy, iron-nickel alloy, etc.) can be used. However, these are merely examples, and other metal magnetic materials may be employed. The metal magnetic powder may be a powder of one type of metal magnetic material or a powder in which two or more types of metal magnetic materials are mixed.

For example, from the viewpoint of magnetic properties and availability, iron is included as a main component, and chromium (Cr), silicon (Si), nickel (Ni), aluminum (Al), and cobalt (Co) are used as subcomponents. , carbon (C), boron (B), or the like may be used. Amorphous metal powder or pure iron powder may also be used. Specifically, Fe—Ni system (permalloy), Fe—Si system (silicon steel), Fe—Al system, Fe—Co system (permendur), Fe—Si—Cr system, Fe—Al—Cr system , Fe--Si--Al system (sendust) and other alloy powders, amorphous metal powders such as Fe--Si--B--Cr system amorphous powders, and crystalline iron powders such as carbonyl iron powders. Among the above materials, materials that can be formed into substantially spherical metallic magnetic powders (for example, Fe--Si--B--Cr system amorphous powders and Fe--Si--Cr system alloy powders) may be used. This is because compression molding of the composite magnetic material containing the metal magnetic powder becomes easier.

The content of iron, which is the main component of the metal magnetic powder, is preferably 85 wt% or more, more preferably 86 wt% or more. And it may contain one or more selected from the above subcomponents, and the balance may be iron and unavoidable impurities.

In addition, the chromium content of this metal magnetic powder may be 2 wt % or more and 10 wt % or less, or may be 2.5 wt % or more and 8 wt % or less.
Chromium combines with atmospheric oxygen to readily form chemically stable oxides (eg, Cr ₂ O ₃ , etc.). Therefore, the composite magnetic thermosetting molding containing chromium has particularly excellent corrosion resistance. Furthermore, since chromium oxide has a high specific resistance, the formation of a chromium oxide layer near the surface of the particles constituting the composite magnetic thermosetting molded body facilitates insulation between the particles.
Therefore, by setting the chromium content within the above range, it is possible to obtain a metal magnetic powder that has excellent corrosion resistance and that can constitute a composite magnetic material that can be used to manufacture coil components and the like with low eddy current loss.

For the same reason, this metal magnetic powder may have a nickel content of 2 wt % or more and 10 wt % or less, or may be 2.5 wt % or more and 8 wt % or less. Similarly, the metal magnetic powder may have an aluminum content of 2 wt % or more and 10 wt % or less, or may be 2.5 wt % or more and 8 wt % or less.

Further, the metal magnetic powder may have a silicon content of 2 wt % or more and 10 wt % or less, or 3 wt % or more and 8 wt % or less.
Silicon is a component that can increase the relative magnetic permeability of a coil component or the like obtained by using a composite magnetic thermosetting molding containing metal magnetic powder. In addition, when the metal magnetic powder contains silicon, the specific resistance increases, so silicon is also a component capable of suppressing inter-particle eddy current loss. Therefore, by setting the content of silicon within the above range, it is possible to obtain a metal magnetic powder that can constitute a composite magnetic material that can be used to manufacture coil parts and the like that have a high relative magnetic permeability and a small eddy current loss.

This metal magnetic powder contains boron (B), titanium (Ti), V (vanadium), manganese (Mn), copper (Cu), Ga (gallium), germanium ( Ge), zirconium (Zr), Nb (niobium), Mo (molybdenum), Ru (ruthenium), Rh (rhodium), and at least one selected from the group consisting of tantalum (Ta). In that case, the total content of these components is preferably 5 wt % or less.
In addition, it may contain components such as phosphorus (P) and sulfur (S) that are unavoidably mixed in the manufacturing process, but in that case, the total content of these components should be 1 wt% or less. preferable.

The average particle size (D ₅₀ ) of the metal magnetic powder is preferably 1 μm or more and 30 μm or less, more preferably 2 μm or more and 25 μm or less. Furthermore, the particle shape of the metal magnetic powder is substantially spherical (for example, the value obtained by dividing the major axis by the minor axis is 2 or less, or even 0.5 or less) is preferable.

Here, this “average particle size (D ₅₀ )” means the powder at an integrated value of 50% in the volume-based particle size distribution obtained using a particle size distribution measuring device based on the laser diffraction/scattering method (microtrack method). Means the diameter (median diameter). When the particles are agglomerated, it means the particle size of the agglomerate. A laser diffraction/scattering type particle size distribution analyzer (particle size distribution) LA-960 (manufactured by HORIBA Ltd.) can be mentioned as a specific measuring instrument for the average particle size (D ₅₀ ).

As the metal magnetic powder, it is preferable to use a metal magnetic material pulverized by a water atomization method or a gas atomization method.
Here, the "water atomization method" is a method in which the molten metal (molten metal) is collided with water (atomized water) jetted at high speed to pulverize and cool the molten metal to produce metal powder. be.
The "gas atomization method" is a method in which a jet stream of inert gas, air, or the like is sprayed from the surroundings of the flow of molten metal to pulverize the flow of molten metal and solidify it into metal powder.

Since the metal magnetic powder produced by the water atomization method or the gas atomization method has a substantially spherical shape (close to a spherical shape), a composite magnetic thermosetting molded body is produced using a composite magnetic material containing this metal magnetic powder. When doing so, the filling rate can be easily increased. Compression molding of the composite magnetic material containing the metal magnetic powder is also facilitated. As a result, it is easy to obtain a composite magnetic thermosetting molded article having a higher density and a higher relative magnetic permeability.

Further, the metal magnetic powder may be dried to remove water adsorbed on the surface of the powder, that is, a dry metal magnetic powder obtained by drying the powder. Examples of the powder drying method include hot air treatment and dry heat treatment, and examples of the drying treatment conditions include conditions in which the powder is treated at a temperature of 100° C. or higher and 150° C. or lower for 30 minutes or longer and 120 minutes or shorter.

The metal magnetic powder may be surface-treated with a silane- or titanium-based coupling agent in order to improve wettability with the thermosetting resin. A surface-treated metal magnetic powder obtained by surface-treating with an agent may also be used. As the silane-based or titanium-based coupling agent, a silane-based or titanium-based coupling agent having an epoxy group, an amino group, or an isocyanate group as a functional group is used from the viewpoint of affinity with the thermosetting resin described later. is more preferred. As a surface treatment method of the powder, there is a dry treatment method in which a solution containing a coupling agent is dropped or sprayed while stirring the powder with a mixer or the like, or a slurry is prepared by adding a solvent to the powder, and the coupling agent is added to the slurry. A wet treatment method of adding a solution containing and stirring, followed by filtration and drying is exemplified. Note that this surface treatment may be performed in combination with the drying treatment described above.

Furthermore, as the metal magnetic powder, a phosphate treatment is performed to coat the surface with an insulating film, that is, a phosphate-treated metal magnetic powder obtained by phosphating the powder with a phosphate. Powder may be used. Phosphates include zinc phosphate, zinc-calcium phosphate, manganese phosphate, and iron phosphate. , more preferably zinc phosphate. Examples of the method of phosphating the powder include a method in which the powder is washed with acid or water as necessary, then subjected to phosphate treatment, and then washed with water and dried. This phosphate treatment may also be performed in combination with the drying treatment described above.

The content of the metal magnetic powder in the composite magnetic material obtained in the material preparation step is preferably 90 wt % or more and 98.5 wt % or less, more preferably 92 wt % or more and 98 wt % or less, and 94 wt % or more. It is more preferably 97.5 wt% or less.

<Thermosetting resin>
A thermosetting resin is a reactive resin composition whose main component is a prepolymer with functional groups. It is a resin composition that softens and flows when heated, and then hardens through a cross-linking reaction that gradually forms a three-dimensional network structure. It is a thing. The composite magnetic thermosetting molded article obtained by the manufacturing method of the composite magnetic thermosetting molded article according to the present embodiment contains a thermoset resin composition. The resin composition that has been processed may also be referred to as a "thermosetting resin". The thermosetting resin is not particularly limited as long as it serves as a binder resin and can be cured by heating (for example, a resin used as a semiconductor sealing material). , epoxy resins (bisphenol type, naphthalene type, novolac type, aliphatic type, glycidylamine type, etc.), silicone resins (methylphenyl silicone resin, etc.), phenolic resins (novolak type, resol type, etc.), polyamide Resins, polyimide resins, melamine resins, polyphenylene sulfide resins, and the like can be used. A mixture of two or more thermosetting resins may also be used. In particular, from the viewpoint of heat resistance, it is more preferable to use an epoxy resin.
In addition, the thermosetting resin is not particularly limited, but it is preferable that it can be softened by holding it in a temperature range of 50 to 140° C. for a predetermined time (for example, about 10 to 120 seconds). is. Although this is also not a limitation, this thermosetting resin can be cured by holding it in a temperature range of 150° C. or higher for a predetermined time (for example, about 0.1 to 5 hours). It is preferable to have

Furthermore, it is preferable that the thermosetting resin is mixed with a curing agent from the viewpoint of easiness of thermosetting. Curing agents include phenol novolac type curing agents (phenol novolac resin, bisphenol A type novolac resin, etc.), polyamide curing agents (polyamide resin, etc.), maleic anhydride, phthalic anhydride and other acid anhydride curing agents, Latent amine curing agents such as dicyandiamide and imidazole, and aromatic amines such as diaminodiphenylmethane and diaminodiphenylsulfone can be used. These curing agents may be used alone or in combination of two or more.
In addition, other additives such as diluents, fillers, release agents, etc. may be further mixed within the range that does not affect the effects of the present invention.

In preparing the composite magnetic material, the thermosetting resin may be mixed with a solvent to obtain a solution containing the thermosetting resin. This solvent is removed by drying or the like in each step (e.g. material preparation step) described later, but from the viewpoint of ease of removal, it is preferable that the amount of solvent used is small (e.g. The ratio of the volume of the solvent to the total volume of the raw materials used for the composite magnetic material is less than 5.0 vol%, or 0.5 vol% or more and 2.0 vol% or less, etc.). The solvent is preferably one that can be removed by drying or the like in each step described later, and organic solvents such as alcohol, toluene, chloroform, methyl ethyl ketone, acetone, and ethyl acetate are preferred examples.

The thermosetting resin content in the composite magnetic material obtained in the material preparation step is preferably 1.5 wt % or more and 5.0 wt % or less, and more preferably 2.0 wt % or more and 4.5 wt % or less. is more preferably 2.5 wt % or more and 4.0 wt % or less.

<High melting point compound>
A high melting point compound is a compound having a melting point of 25° C. or more and less than 100° C. and a boiling point of 160° C. or more. Since this high melting point compound is solid at room temperature (20±5° C.), the composite magnetic material containing a predetermined amount of this high melting point compound has good fluidity as a powder when supplied to a mold. In other words, it becomes powdery with fluidity. In addition, since the high-melting point compound becomes liquid at 100° C. or higher and is included so as to fall within the mass range described later with respect to the mass of the thermosetting resin that softens when heated, the composite magnetic material is compressed during thermoforming. At times, it becomes liquid with fluidity. Regardless of the characteristics of the thermosetting resin contained in the composite magnetic material, the properties as described above can be obtained by including a predetermined amount of such a high melting point compound in the composite magnetic material. Furthermore, since this high melting point compound has a boiling point of 160° C. or higher, it is difficult to volatilize at 40° C. or lower. Secured. In addition, volatilization of the high-melting point compound can be suppressed even during operations such as the material preparation process and the compression molding process, which will be described later.

Although not limited, the melting point of the high-melting point compound is preferably higher than 35°C, more preferably 45°C or higher, and even more preferably 49°C or higher. Moreover, the upper limit of the melting point is more preferably 80° C. or lower, and even more preferably 75° C. or lower. Although this is also not limited, the boiling point is preferably 170° C. or higher, more preferably 180° C. or higher, even more preferably 200° C. or higher, and 210° C. or higher. is more preferred. In addition, the upper limit of the boiling point is more preferably 330° C. or less, more preferably 310° C. or less, and even more preferably 300° C. or less from the viewpoint of ease of removal of high melting point compounds in the heat curing step described later. preferable.

Such high-melting compounds include cyclohexanol, p-cresol, phenol, L-menthol (menthol), benzophenone, α,α'-dichloro-o-xylene, stearyl alcohol, 3,5-dimethylphenol, butylhydroxy Examples include toluene and coumarin. And one or more selected from the group consisting of these can be used, and two or more can also be used together. In particular, it is preferable to use butylhydroxytoluene and/or coumarin as the high-melting point compound from the viewpoint of production aptitude and cost.

The mass of the high-melting point compound in the composite magnetic material obtained in the material preparation step should be 3.0 wt % or more and 100 wt % or less with respect to the mass of the thermosetting resin contained in the composite magnetic material. The lower limit is more preferably 5.0 wt% or more, more preferably 7.0 wt% or more, even more preferably 10 wt% or more. The upper limit is more preferably 80 wt% or less, even more preferably 60 wt% or less, even more preferably 50 wt% or less, and even more preferably 33 wt% or less.
The content of the high melting point compound in the total mass of the composite magnetic material obtained in the material preparation process may be 0.05 wt % or more and 5.0 wt % or less, and further 0.1 wt % or more and 3.0 wt % or less. , or more preferably 0.3 wt % or more and 1.0 wt % or less.

In preparing the composite magnetic material, the high melting point compound may be mixed with the same solvent as used for the thermosetting resin. Also, a thermosetting resin and a high melting point compound may be mixed together with the solvent. The types and mixing ratios of the solvents may be the same as those described above.

A powdery composite magnetic material is prepared by using such a metal magnetic powder, a thermosetting resin, and a predetermined high-melting point compound. For example, a dispersant, a plasticizer, a lubricant, etc.) may be mixed to prepare a composite magnetic material.
Further, since this powdery composite magnetic material can be more easily supplied to a mold, it may be granulated powder (granulated powder of composite magnetic material).

<Manufacturing Method of Composite Magnetic Thermosetting Molded Body>
Next, each step of the manufacturing method of the composite magnetic thermosetting molding according to this embodiment will be described in detail.

The manufacturing method of the composite magnetic thermosetting molding according to the present embodiment includes at least the following material preparation process, compression molding process, and heat curing process. The composite magnetic thermosetting molded body manufactured by this manufacturing method includes not only a non-embedded type magnetic core material in which a coil is not embedded, but also a coil component in which a coil is embedded. .
Each of the above steps will be described in detail below.

[Material preparation process]
The material preparation step is a step of obtaining a powdery composite magnetic material composed of a metal magnetic powder, a thermosetting resin, and a predetermined high melting point compound. Specifically, a metal magnetic powder, a thermosetting resin, and a high melting point compound as described above are prepared, and a mixer or the like is used to mix the thermosetting resin and the high melting point compound (for example, a solution obtained by adding a solvent to these). Then, the metal magnetic powder is mixed and dispersed, granulated if necessary, and dried to prepare a powdery composite magnetic material (composite magnetic material powder or granulated powder). Here, if necessary, a dispersant, a plasticizer, or the like may be appropriately blended before mixing and dispersing. The mass of the high-melting point compound in the composite magnetic material should be 3.0 wt % or more and 100 wt % or less with respect to the mass of the thermosetting resin contained in the composite magnetic material.

The order of mixing the metal magnetic powder, the thermosetting resin, the high-melting compound, and the solvent is not limited. It is more preferable to mix the metal magnetic powder (and other materials) with the solution obtained by mixing with the solvent. The above mixing may be kneading and granulation. Further, when granulated powder of the composite magnetic material is obtained by granulation, classification may be performed after granulation or drying. Classification methods include, for example, sieving classification, inertial classification, dry classification such as centrifugal classification, and wet classification such as sedimentation classification. If a solvent is used, it is preferable to dry the mixture after mixing so that the solvent content is approximately 0 vol %. Moreover, this material preparation step is preferably performed in an environment where the ambient temperature is room temperature (20±5° C.).

[Compression molding process]
The compression molding step is a step of compression molding the composite magnetic material obtained in the material preparation step under predetermined conditions to obtain a composite magnetic molded body. Specifically, first, the mold of the press machine is adjusted to 100° C. or higher (temperature exceeding the melting point of the high melting point compound contained in the composite magnetic material), and the composite magnetic material is injected from the opening of this mold using an injector or the like. is supplied into the mold and liquefied. The shape and size of the mold are not particularly limited. In addition, when the composite magnetic material is put into the mold, the injection may be performed while applying vibration in order to prevent the occurrence of a portion where the composite magnetic material is not sufficiently filled inside the mold. Here, to make the composite magnetic material “liquid” means to make the composite magnetic material in a fluid state containing liquid or paste. is

After supplying the composite magnetic material into a mold adjusted to 100° C. or higher, the mold may be held for about 10 to 120 seconds before compression molding. This makes it easier for the composite magnetic material supplied to the mold to become liquid.

Furthermore, this mold makes it difficult for the thermosetting resin contained in the composite magnetic material to proceed with the thermosetting reaction before and during compression molding, and can further suppress volatilization of the high melting point compound. It is more preferable that the temperature is adjusted to 140° C. or lower.

After that, compression molding is performed with a molding pressure of 1000 kgf/cm ² or less (9.8 × 10 ³ N/cm ² or less) from both the top and bottom of the mold or either one of the top and bottom using a movable punch (press head) or the like. A molded body is obtained. The molding pressure is preferably 800 kgf/cm ² or less (7.84×10 ³ N/cm ² or less), and 500 kgf/cm ² or less (4.9×10 ³ N/cm ² or less). ) is more preferred. Also, it is preferably 3 kgf/cm ² or more (2.94×10 N/cm ² or more), more preferably 5 kgf/cm ² or more (4.9×10 N/cm ² or more). . Although the compression molding time is not limited, it is preferably 5 seconds or more and 5 minutes or less.
The density of the composite magnetic material is 5.45 g/cm ³ or more while it is in a fluid state by molding pressure of 1000 kgf/cm ² or less from either the top or bottom of the mold. It is more preferable to obtain a composite magnetic molded body by compression molding so that it is preferably 5.50 g/cm ³ or more. This is because it is easy to form a composite magnetic molded body with a high density.

Here, "compression molding is performed so that the density of the liquid composite magnetic material becomes 5.45 g/cm ³ or more while it is in a fluid state" means that the density of the composite magnetic material is 5.45 g/cm 3 . cm ³ or more, the state in which the composite magnetic material has fluidity is maintained (for example, the melt viscosity of the composite magnetic material is 1300 Ps·s or less, further 1100 Ps·s or less), In other words, compression molding is performed so that the density becomes 5.45 g/cm ³ or more before the thermosetting reaction of the thermosetting resin contained in the composite magnetic material substantially progresses. Although it varies depending on the type of thermosetting resin contained in the composite magnetic material, as a guide, for example, when epoxy resin is contained, the density is 5.5 in 5 to 120 seconds, further 5 to 90 seconds from the start of compression molding. It is preferable to perform compression molding so as to obtain 45 g/cm ³ or more.
After the density reaches 5.45 g/cm ³ or more, the composite magnetic material becomes non-fluid (a state in which the thermosetting reaction of the contained thermosetting resin has substantially progressed). It's okay to be there.

[Thermal curing process]
In the thermosetting process, the composite magnetic molded body obtained in the compression molding process is heat-treated to volatilize and remove the high-melting point compound contained in the composite magnetic molded body, while the thermosetting resin is heat-cured to produce a composite magnetic heat. This is the step of obtaining a cured molding. Specifically, the composite magnetic molded body after the compression molding process is heat-treated at a temperature equal to or higher than the recommended thermosetting temperature of the contained thermosetting resin to thermoset it. The temperature of this heat treatment may be appropriately set according to the type of the thermosetting resin contained in the composite magnetic material. be done. The heat treatment time may also be, for example, 0.1 hours or more and 5 hours or less, or may be 0.2 hours or more and 3 hours or less. This heat treatment may be performed in the mold, after it is removed from the mold, or both. After that, the resulting composite magnetic thermosetting molding can be selectively subjected to surface polishing, coating, or the like, if necessary.

In this thermosetting step, the high melting point compound contained in the composite magnetic molded body is volatilized and removed, and the high melting point compound is substantially absent (the content of the high melting point compound is less than 0.1 wt%, and further is less than 0.05 wt%), but not limited to this, and a part of the high melting point compound contained in the composite magnetic molded body remains (for example, high The content of the melting point compound is 0.1 wt % or more and 1.0 wt % or less, further 0.5 wt % or more and 0.9 wt % or less).

In this manner, a composite magnetic thermosetting molding composed of metal magnetic powder and thermosetting resin can be produced. The density of this composite magnetic thermosetting molding can be 5.45 g/cm ³ or more, and can be 5.50 g/cm ³ or more. Further, the relative magnetic permeability of this composite magnetic thermosetting molding can be 24.0 or more, and can be 25.0 or more.

In the case where the compression molding process described above is a process of encapsulating a coil in a composite magnetic material and integrally compressing and molding the composite magnetic material to obtain a composite magnetic molded body in which the coil is encapsulated, this is also not limited. As a modification of the method of manufacturing the composite magnetic thermosetting molding according to the present embodiment, a coil component can be manufactured by the steps shown in FIG. 1, for example.

Specifically, first, an air-core coil 11 formed of a wire such as a round wire is prepared ((a) in FIG. 1). The air-core coil 11 is composed of a winding portion around which a wire wire coated with insulation is wound, and a coil lead-out portion 12 from which the wire wire is pulled out from the winding portion. Next, the mold 21 containing the lower punch of the press machine is adjusted to 100° C. or higher, the air-core coil 11 is placed in this mold 21, and the coil winding portion (wound portion) is opened from the opening of the mold 21. The powdery composite magnetic material 22 prepared by the material preparation process described above is supplied so as to fill the inside of the loops of the wire and the gaps between the loops) and the upper and lower spaces thereof. However, the two coil lead-out portions 12 of the winding are exposed from the composite magnetic material 22 (FIG. 1(b)). Then, the temperature-controlled upper punch is used to perform compression molding under the aforementioned molding pressure, and the composite magnetic material 22 and the air-core coil 11 are integrally molded by compression to obtain a coil-containing composite magnetic molded body (( in FIG. 1). c)). After that, the coil-containing composite magnetic molded body is taken out from the mold, and heat-cured by heat treatment at a predetermined temperature to volatilize and remove the high-melting-point compound, and heat-cured composite magnetic thermoset molded body 32. It is possible to obtain a coil component in which the air-core coil 11 is embedded in (the magnetic outer casing and the magnetic core material serving as the magnetic core), and the two coil lead-out portions 12 are exposed to the outside and serve as terminals (see FIG. 1). (d)).

Instead of the air-core coil, a coil assembly composed of a coil and another magnetic core material that serves as a magnetic core may be prepared and used to manufacture the coil component by the same method as described above. In this case, the magnetic exterior (outer core material) is composed of the above composite magnetic thermosetting molded body, but the magnetic core (inner core material) is made of a material different from the above composite magnetic thermosetting molded body (for example, a ferrite core, etc.). ) becomes a coil component. However, it is more preferable to use a coil component in which both the outer core material and the inner core material are composed of the composite magnetic thermosetting molded body described above.

The method of manufacturing a composite magnetic thermosetting molding according to the present embodiment has been described above, but the present invention is not limited to the above-described embodiment, and various modifications, Embodiments such as improvements are also included.
Moreover, the above-described embodiments can be appropriately combined without departing from the gist of the present invention.

Examples of the present invention will be described below, but the present invention is not limited to the following examples, and as described above, various modifications and the like are possible within the technical concept of the present invention.

(Example 1)
As the metal magnetic powder used for the composite magnetic material, a mixture of an iron powder grade with an average particle size ( _D50 ) of about 25 μm and an iron powder grade with an average particle size ( _D50 ) of about 2 μm is prepared. A thermosetting epoxy resin (curing temperature: 210° C.) containing a curing agent was prepared as a hardening resin. Also, benzophenone (melting point: 49° C., boiling point: 305° C.) was prepared as a high melting point compound used for the composite magnetic material.

First, a predetermined amount of benzophenone was weighed and mixed with methyl ethyl ketone (MEK). Further, a predetermined amount of the above-mentioned epoxy resin was weighed and mixed, and sufficiently dissolved to form a solution. A predetermined amount of the above-mentioned metal magnetic powder was mixed with the solution and thoroughly stirred with a planetary mixer to prepare a slurry. . Further, after granulating this slurry, methyl ethyl ketone (MEK) as a dilution solvent was dried to obtain granulated powder of the composite magnetic material. The mass of the epoxy resin was 3 wt % and the mass of benzophenone was 0.5 wt % (17 wt % with respect to the mass of the epoxy resin) in the total mass of the granulated powder of the composite magnetic material.

A control composite magnetic material granulated powder was also produced in the same manner as above except that benzophenone was not blended. The mass of the epoxy resin in the total mass of the granulated powder of the composite magnetic material was 3 wt %.

Next, the temperature of the mold including the lower punch of the press machine with the built-in air cylinder and capable of temperature adjustment control was adjusted to 100° C. or more and 140° C. or less. When the mold temperature was stabilized, one of the above granulated powders of the composite magnetic material was supplied into the mold and held as it was for 30 seconds to make the temperature almost the same as the mold temperature. After 30 seconds had passed, an upper punch adjusted to the same temperature was inserted, and compression molding was performed by applying a molding pressure of 100 kgf/cm ² (9.8×10 ² N/cm ² ) to the upper punch. Then, after each compressed state was held for 5 minutes, each composite magnetic molded body obtained was taken out from the mold. Furthermore, the composite magnetic molded body taken out from the mold was subjected to heat treatment at 200° C. for 2 hours, and the thermosetting resin was heat-cured (after-cured) to obtain two types of disc-shaped composite magnetic thermosetting molded bodies. .
All of the granulated powders had good fluidity as powders when supplied to the mold. Also, the composite magnetic material containing benzophenone was in a fluid state at the start of compression molding and until it reached a predetermined density (5.45 g/cm ³ or more).

The disc-shaped composite magnetic thermosetting molded body was used to evaluate the density of the obtained composite magnetic thermosetting molded body. In addition, a toroidal-shaped composite magnetic thermosetting molded body was produced by drilling a hole in the center of this disk-shaped composite magnetic thermosetting molded body, and the relative magnetic permeability of the obtained composite magnetic thermosetting molded body was evaluated. , this toroidal-shaped composite magnetic thermosetting molding was used.

As a specific evaluation method, the density was evaluated by calculating from the measured values of the outer diameter, height, and mass of the disk-shaped composite magnetic thermosetting molding. The relative magnetic permeability was measured by winding 20 turns of an insulated copper wire (enameled wire) around a toroidal-shaped composite magnetic thermosetting molding and measuring the inductance value with an LCR meter (E4980A LCR Meter manufactured by Agilent). A core multiplier was calculated from the outer diameter, inner diameter, and thickness of the composite magnetic thermosetting molding, and the relative permeability was calculated from the inductance value.

As a result, the density of the composite magnetic thermosetting molding produced using the composite magnetic material containing benzophenone was 5.62 g/cm ³ and the relative magnetic permeability was 26.2. The density of the composite magnetic thermosetting molded body produced using the composite magnetic material without the magnetic field was 5.37 g/cm ³ and the relative magnetic permeability was 23.2. In other words, by using a composite magnetic material containing a high-melting point compound, it was found that a composite magnetic thermosetting molded body with high density and high relative magnetic permeability can be obtained with a low molding pressure.

Furthermore, the properties of the granulated powder of the composite magnetic material containing benzophenone prepared above or the granulated powder of the control composite magnetic material at room temperature (20±5° C.) and 100° C. were confirmed and photographed. This photograph is shown in FIG. As a result, the granulated powder of the composite magnetic material containing benzophenone was poured into the mold as shown in the lower left photograph of FIG. In the state at the time of supply of , the fluidity as a powder was good, like the granulated powder of the control composite magnetic material (upper left in FIG. 2). On the other hand, since benzophenone is liquefied at 100° C., the granulated powder of the composite magnetic material containing benzophenone is liquefied during thermoforming (bottom right in FIG. 2), and is powdery even during thermoforming. It was shown to have different properties from the granulated powder of the control composite magnetic material (upper right side of FIG. 2).

(Example 2)
The same metal magnetic powder and thermosetting resin as in Example 1 were prepared for use in the composite magnetic material. Also, 12 types of compounds shown in Table 1 below were prepared as high-melting compounds used for the composite magnetic material.

Then, 12 kinds of granulated powders of composite magnetic materials were produced in the same manner as in Example 1 (No. 7 in Table 1 below is the same as that produced in Example 1). The mass of the epoxy resin in the total mass of the granulated powder of the composite magnetic material was 3 wt %, and the mass of the high melting point compound was 0.5 wt % (17 wt % with respect to the mass of the epoxy resin). Furthermore, a composite magnetic thermosetting molded body was also produced by the same method as in Example 1, and the fluidity when the granulated powder was supplied to the mold (fluidity during powder feeding) and 1000 kgf/cm ² or less were measured. Whether or not a high-density molded body can be produced even at a low molding pressure (low molding pressure effect) was evaluated in three stages. In addition, whether or not the high-melting point compound contained in the granulated powder of the composite magnetic material remained during the preparation of the granulated powder and during storage at 40° C. for 24 hours was evaluated on a three-grade scale. Comprehensive judgment was also performed in three stages based on the evaluation of the three items. The results are also shown in Table 1 below. The specific evaluation criteria for each item are as follows.

<Flowability during powder feeding>
◎: No change in fluidity ○: Fluidity changed but powdering possible ×: Fluidity deteriorates <Effect of low molding pressure>
◎: Change in density at low molding pressure (>10%)
○: Change in density at low molding pressure (≦ 10%)
×: No change in density at low molding pressure <storage stability>
◎: No weight change during storage 〇: Weight change during storage ×: Volatilization progresses during work <Comprehensive judgment>
◎: Evaluation of all the above items is ◎ ○: Evaluation of all the above items is ○ or more ×: Evaluation of the above items has 1 or more

From this result, in order for the composite magnetic material to have fluidity as a powder when supplied to a mold, the high melting point compound contained must be solid at room temperature, that is, the melting point must be 25° C. or higher. shown to be necessary. In addition, in order to ensure the storage stability of the composite magnetic material at 40° C. or lower (for example, 10° C. or higher and 40° C. or lower), it is necessary that the contained high-melting point compounds hardly volatilize in this temperature range. was required to be 160° C. or higher. Furthermore, it was shown that the melting point of the high melting point compound contained in the composite magnetic material must be less than 100°C in order to perform thermoforming at 100°C or higher (for example, 100°C or higher and 140°C or lower).

(Example 3)
The same metal magnetic powder and thermosetting resin as in Example 1 were prepared for use in the composite magnetic material. In addition, coumarin (melting point: 73°C, boiling point: 298°C) was prepared as a high-melting compound used for the composite magnetic material.

Then, 9 types of granulated powders of composite magnetic materials were produced in the same manner as in Example 1 except that the blending amounts were changed to the amounts shown in Table 2 below (No. 25 in Table 2 below is No. 2 of Example 2 .12). Furthermore, a composite magnetic thermosetting molded body was produced by the same method as in Example 1, and the fluidity during powder feeding and the effect of reducing the molding pressure were evaluated in three stages according to the same criteria as in Example 2. Then, similarly to Example 2, comprehensive judgment was also made in three stages based on the evaluation of these two items. The results are also shown in Table 2 below.

From this result, the mass ratio of the high melting point compound in the composite magnetic material is preferably 3 wt% or more and 100 wt% or less, and particularly preferably 10 wt% or more and 33 wt% or less, with respect to the mass of the thermosetting resin. It has been shown.

This embodiment includes the following technical ideas.
(1) A method for manufacturing a composite magnetic thermosetting molded body including a material preparation step, a compression molding step, and a thermosetting step, wherein the material preparation step includes metal magnetic powder, thermosetting resin, A high melting point compound having a melting point of 25° C. or more and less than 100° C. and a boiling point of 150° C. or more, and a mass of the high melting point compound of 3.0 wt % or more and 100 wt % or less with respect to the mass of the thermosetting resin. In the compression molding step, the composite magnetic material is supplied to a mold adjusted to a temperature of 100° C. or higher to be liquefied, and 1000 kgf/cm ² . In the heat curing step, the composite magnetic molded body is heat-treated to volatilize and remove the high-melting compound while the thermosetting resin is formed. is heat-cured to obtain the composite magnetic thermosetting molded body.
(2) In the compression molding step, a molding pressure of 1000 kgf/cm ² or less is used to compress the liquid composite magnetic material to a density of 5.45 g/cm ³ or more while it is in a fluid state. The method for producing a composite magnetic thermosetting molding according to (1), wherein the molding is performed.
(3) The method for producing a composite magnetic thermosetting molding according to (1) or (2), wherein the high melting point compound in the material preparation step has a melting point of 80° C. or lower and a boiling point of 330° C. or lower.
(4) The composite according to any one of (1) to (3), wherein in the compression molding step, the composite magnetic material is supplied to the mold adjusted to a temperature of 100° C. or higher and 140° C. or lower. A method for producing a magnetic thermosetting molding.
(5) Any one of (1) to (4), wherein the compression molding step is a step of encapsulating a coil in the composite magnetic material and integrally compressing and molding the composite magnetic material to obtain the composite magnetic molded body in which the coil is encapsulated. 3. A method for manufacturing a composite magnetic thermosetting molding according to claim 1.

11 Air-core coil 12 Coil drawer 21 Mold 22 Composite magnetic material 32 Composite magnetic thermosetting molding

Claims (5)

A method for manufacturing a composite magnetic thermosetting molding comprising a material preparation step, a compression molding step, and a thermosetting step,
In the material preparation step, a metal magnetic powder, a thermosetting resin, and a high melting point compound having a melting point of 25° C. or higher and lower than 100° C. and a boiling point of 160° C. or higher are added to the mass of the thermosetting resin. On the other hand, a step of obtaining a powdery composite magnetic material by mixing so that the mass of the high melting point compound is 3.0 wt % or more and 100 wt % or less,
The compression molding step is a step of supplying the composite magnetic material to a mold adjusted to a temperature of 100° C. or higher to liquefy it, and performing compression molding with a molding pressure of 1000 kgf/cm ² or less to obtain a composite magnetic molded body.
The thermosetting step is a step of heat-treating the composite magnetic molded body to thermally cure the thermosetting resin while volatilizing and removing the high melting point compound to obtain the composite magnetic thermosetting molded body.
A method for manufacturing a composite magnetic thermosetting molding. In the compression molding step, compression molding is performed with a molding pressure of 1000 kgf/cm ² or less so that the density of the liquid composite magnetic material is 5.45 g/cm ³ or more while it is in a fluid state. 2. The method for manufacturing the composite magnetic thermosetting molding according to claim 1. 3. The method for producing a composite magnetic thermosetting molding according to claim 1, wherein said high melting point compound in said material preparation step has a melting point of 80[deg.] C. or less and a boiling point of 330[deg.] C. or less. The composite magnetic thermosetting molded article according to any one of claims 1 to 3, wherein in the compression molding step, the composite magnetic material is supplied to the mold adjusted to a temperature of 100°C or higher and 140°C or lower. manufacturing method. 5. The compression molding step is a step of encapsulating a coil in the composite magnetic material and subjecting the composite magnetic material to integral compression molding to obtain the composite magnetic molded body in which the coil is encapsulated. A method for manufacturing a composite magnetic thermosetting molded body.

Images