Magnetic composite material and cured product

Abstract

This magnetic composite material contains a soft magnetic powder and a resin composition. The soft magnetic powder includes a plurality of submicron particles and a plurality of large particles having a larger particle diameter than the submicron particles. The resin composition contains a thermosetting resin. At least some of the submicron particles are an alloy that contains iron. The content of the plurality of submicron particles in the magnetic composite material is denoted by V1 vol%. The content of the plurality of large particles in the magnetic composite material is denoted by V2 vol%. The value of V2 / V1 is not less than 1.0 and less than 28.0.

Description

Magnetic composite materials and hardened materials

[0001] The present disclosure relates to magnetic composite materials and cured products.

[0002] Magnetic composite materials containing soft magnetic powder and resin compositions are used as raw materials for various industrial products (see Patent Document 1 below). For example, magnetic composite materials are used as raw materials for inductors, power supply modules, transformers, reactors, thyristor valves, noise filters (EMI filters), choke coils, motors (cores, rotors, and yokes), electromagnetic wave shields, and solenoid cores (stationary iron cores) for electromagnetic valves.

[0003] JP 2017-103287 A

[0004] K. Murata, T. Miyazaki, H. Masumoto, and Y. Endo: Transaction of the Magnetics Society of Japan (Special Issues) Vol.5, No.1, 2021

[0005] An object of one aspect of the present disclosure is to provide a magnetic composite material that reduces magnetic loss and further increases the mechanical strength of a cured product of the magnetic composite material, and a cured product of the magnetic composite material.

[0006] For example, one aspect of the present disclosure relates to a magnetic composite material described in any one of [1] to

[14] below, and a cured product described in

[15] below.

[0007] [1] A magnetic composite material comprising a soft magnetic powder and a resin composition, wherein the soft magnetic powder comprises a plurality of submicron particles and a plurality of large particles having a particle size larger than that of the submicron particles, the resin composition comprises a thermosetting resin, at least some of the submicron particles are an alloy containing iron, the content of the submicron particles in the magnetic composite material is expressed as V1 vol%, the content of the large particles in the magnetic composite material is expressed as V2 vol%, and V2 / V1 is 1.0 or more and less than 28.0.

[0008] [2] The magnetic composite material according to [1], wherein the large particles have a particle size of 5.0 μm or less.

[0009] [3] The magnetic composite material according to [1], wherein the large particles have a particle size of 2.5 μm or less.

[0010] [4] The magnetic composite material according to any one of [1] to [3], wherein at least some of the large particles contain at least one selected from the group consisting of ferrite, pure iron, and alloys.

[0011] [5] The magnetic composite material according to any one of [1] to [4], wherein at least some of the submicron particles are an alloy containing iron and boron.

[0012] [6] The magnetic composite material according to any one of [1] to [5], wherein at least some of the submicron particles are an alloy containing iron, boron, and nickel.

[0013] [7] The magnetic composite material according to [6], wherein the content of the nickel in the submicron particles is 15 atomic % or more and 55 atomic % or less.

[0014] [8] The magnetic composite material according to any one of [1] to [7], wherein at least some of the submicron particles comprise nanocrystals.

[0015] [9] The magnetic composite material according to any one of [1] to [8], wherein the content of the soft magnetic powder in the magnetic composite material is 50% by volume or more and less than 100% by volume.

[0016]

[10] The magnetic composite material according to any one of [1] to [8], wherein the content of the soft magnetic powder in the magnetic composite material is 80% by volume or more and less than 100% by volume.

[0017]

[11] The magnetic composite material according to any one of [1] to

[10] , wherein the particle diameter of the submicron particles is 0.1 μm or more and less than 0.5 μm.

[0018]

[12] The magnetic composite material according to any one of [1] to

[11] , which is a magnetic paste.

[0019]

[13] The magnetic composite material according to any one of [1] to

[11] , which is a magnetic film.

[0020]

[14] The magnetic composite material according to any one of [1] to

[11] , which is a magnetic powder.

[0021]

[15] A cured product of the magnetic composite material according to any one of [1] to

[14] .

[0022] According to one aspect of the present disclosure, there are provided a magnetic composite material that reduces magnetic loss in the magnetic composite material and further increases the mechanical strength of a cured product of the magnetic composite material, and a cured product of the magnetic composite material.

[0023] Preferred embodiments of the present disclosure are described below. In this disclosure, an "-based alloy" means an "alloy containing." In this disclosure, an "alloy" means at least one composition selected from the group consisting of a solid solution, a eutectic, and an intermetallic compound. The technical scope of the present disclosure is not limited to the following embodiments.

[0024] (Outline of Magnetic Composite Material and Cured Product) The magnetic composite material according to this embodiment includes a soft magnetic powder and a resin composition. The magnetic composite material may be a mixture including a soft magnetic powder and a resin composition. The resin composition may be defined as the remaining non-volatile components of the magnetic composite material excluding the soft magnetic powder. The resin composition includes at least a thermosetting resin. The magnetic composite material may include, as the resin composition, one or both of an uncured resin composition and a semi-cured resin composition (a B-stage resin composition). The resin composition may cover a portion or the entire surface of each of the soft magnetic particles that make up the soft magnetic powder. The magnetic composite material may consist only of a soft magnetic powder and a resin composition. The magnetic composite material may further include other components (e.g., an organic solvent) in addition to the soft magnetic powder and the resin composition. The magnetic composite material may be referred to as a compound. The cured product of the magnetic composite material according to this embodiment includes a soft magnetic powder and a cured product of the resin composition. In the cured product of the magnetic composite material, the cured product of the resin composition binds the soft magnetic particles that make up the soft magnetic powder to each other. As a result, the cured product of the magnetic composite material can have mechanical strength. The resin composition and its cured product have electrical insulation properties. The resin composition or its cured product interposed between adjacent soft magnetic particles electrically insulates the adjacent soft magnetic particles.

[0025] The soft magnetic powder includes a plurality of submicron particles and a plurality of large particles as the plurality of soft magnetic particles. The large particles are soft magnetic particles having a particle size larger than that of the submicron particles. The soft magnetic powder may consist of only submicron particles and large particles. At least some or all of the submicron particles are alloys containing iron (Fe-based alloys). The content of all submicron particles in the magnetic composite material is expressed as V1 vol%. The content of all large particles in the magnetic composite material is expressed as V2 vol%. V2 / V1 is 1.0 or more and less than 28.0. For example, the units of V1 and V2 are cc and cm, respectively. ３ , or m ３V2 / V1 may be 1.30 or more and 6.49 or less. Since the magnetic composite material according to this embodiment contains submicron particles that are Fe-based alloys, magnetic loss (eddy current loss) can be suppressed compared to conventional magnetic composite materials (e.g., materials containing ferrite powder instead of submicron particles). For example, the tanδ (magnetic loss coefficient) of the magnetic composite material according to this embodiment is lower than the tanδ of conventional magnetic composite materials containing ferrite powder. For example, tanδ may be defined as μ″ / μ′. μ″ is the imaginary part of the complex relative permeability of the magnetic composite material, and μ′ is the real part of the complex relative permeability of the magnetic composite material. Furthermore, since the magnetic composite material according to this embodiment contains submicron particles that are Fe-based alloys, it can also have a higher saturation magnetization compared to conventional magnetic composite materials containing ferrite powder. If the soft magnetic powder were composed only of a plurality of large particles, gaps would easily form between adjacent large particles, and the resin composition would easily fill the gaps between the large particles. Therefore, if the soft magnetic powder consists only of multiple large particles, it is difficult to increase the filling rate of the soft magnetic powder in the magnetic composite material. However, the magnetic composite material according to this embodiment includes not only large particles but also submicron particles as the soft magnetic powder. As a result, one or more submicron particles are likely to fill the gaps between the multiple large particles, and the filling rate of the soft magnetic powder in the magnetic composite material is likely to increase. As the filling rate of the soft magnetic powder (the volume ratio of the soft magnetic powder to the unit volume of the magnetic composite material) increases, the cured product of the magnetic composite material becomes denser and the mechanical strength of the cured product increases. Furthermore, as the filling rate of the soft magnetic powder in the magnetic composite material increases, the magnetic permeability and saturation magnetization of the magnetic composite material also tend to increase. In the production of industrial products using the magnetic composite material, the heated magnetic composite material is kneaded and molded. The heated resin composition flows between the multiple soft magnetic particles, enabling the magnetic composite material to be kneaded and molded. When the filling rate of the soft magnetic powder in the magnetic composite material is maintained constant, the spacing between the soft magnetic particles becomes narrower as the particle size of the soft magnetic particles decreases, making it difficult for the resin composition to flow between the soft magnetic particles. In other words, when the spacing between the soft magnetic particles is maintained at a spacing suitable for the flow of the resin composition, the filling rate of the soft magnetic powder decreases as the particle size of the soft magnetic particles decreases.Therefore, if the soft magnetic powder consists only of a plurality of submicron particles, it is difficult to achieve both the fluidity of the resin composition during kneading and molding and a high filling rate of the soft magnetic powder. However, the magnetic composite material according to this embodiment contains not only submicron particles but also large particles as soft magnetic powder, so the filling rate of the soft magnetic powder can be increased without excessively impairing the fluidity of the resin composition during kneading and molding. Furthermore, since the V2 / V1 ratio of the magnetic composite material according to this embodiment is 1.0 or more and less than 28.0, the cured product of the magnetic composite material is likely to be dense, and the mechanical strength of the cured product is likely to be improved. In other words, the high mechanical strength of the cured product of the magnetic composite material according to this embodiment is due not only to the filling rate of the soft magnetic powder but also to the V2 / V1 range discovered for the first time through the inventors' research. For example, even if the filling rate of the soft magnetic powder in a magnetic composite material in which V2 / V1 is within the above range is equal to the filling rate of the soft magnetic powder in a magnetic composite material in which V2 / V1 is outside the above range, the mechanical strength of the cured product of the magnetic composite material in which V2 / V1 is within the above range is likely to be higher than the mechanical strength of the cured product of the magnetic composite material in which V2 / V1 is outside the above range.

[0026] The particle size of the submicron particles may be 0.1 μm or more and 1.0 μm or less, 0.1 μm or more and less than 0.5 μm, or 0.1 μm or more and 0.49 μm or less, because this facilitates an increase in the filling rate of the soft magnetic powder in the magnetic composite material and facilitates an increase in the mechanical strength of the cured product of the magnetic composite material. For example, the particle size of each of the plurality of submicron particles may be 0.1 μm or more and 1.0 μm or less, 0.1 μm or more and less than 0.5 μm, or 0.1 μm or more and 0.49 μm or less. For example, the average particle size or median diameter D50 of the plurality of submicron particles may be 0.1 μm or more and 1.0 μm or less, 0.1 μm or more and less than 0.5 μm, or 0.1 μm or more and 0.49 μm or less. The smaller the particle size of the submicron particles (especially submicron particles containing iron and boron), the higher the magnetic permeability of the magnetic composite material, the higher the saturation magnetization of the magnetic composite material, and the lower the magnetic loss of the magnetic composite material.

[0027] Because the filling rate of the soft magnetic powder in the magnetic composite material is likely to increase and the mechanical strength of the cured product of the magnetic composite material is likely to increase, the particle size of the large particles may be 1.0 μm or more and 5.0 μm or less, greater than 1.0 μm and 5.0 μm or less, 1.0 μm or more and 2.5 μm or less, greater than 1.0 μm and 2.5 μm or less, 1.5 μm or more and 5.0 μm or less, 1.5 μm or more and 2.5 μm or less, 1.0 μm or more and 2.2 μm or less, 1.0 μm or more and 3.3 μm or less, greater than 1.0 μm and 3.3 μm or less, or 2.2 μm or more and 3.3 μm or less. For example, the particle size of each of the plurality of large particles may be 1.0 μm or more and 5.0 μm or less, greater than 1.0 μm and 5.0 μm or less, 1.0 μm or more and 2.5 μm or less, greater than 1.0 μm and 2.5 μm or less, 1.5 μm or more and 5.0 μm or less, 1.5 μm or more and 2.5 μm or less, 1.0 μm or more and 2.2 μm or less, 1.0 μm or more and 3.3 μm or less, greater than 1.0 μm and 3.3 μm or less, or 2.2 μm or more and 3.3 μm or less. For example, the average particle size or median diameter D50 of the plurality of large particles may be 1.0 μm or more and 5.0 μm or less, greater than 1.0 μm and 5.0 μm or less, 1.0 μm or more and 2.5 μm or less, greater than 1.0 μm and 2.5 μm or less, 1.5 μm or more and 5.0 μm or less, 1.5 μm or more and 2.5 μm or less, 1.0 μm or more and 2.2 μm or less, 1.0 μm or more and 3.3 μm or less, greater than 1.0 μm and 3.3 μm or less, or 2.2 μm or more and 3.3 μm or less.

[0028] For example, the particle sizes of the submicron particles and the large particles may be calculated from the volumetric particle size distribution of the magnetic composite material. For example, the particle size distribution may be measured using a laser diffraction / scattering particle size distribution analyzer. The shapes of the submicron particles and the large particles are not particularly limited. For example, the shapes of the submicron particles and the large particles may be approximately spherical, flat, or acicular.

[0029] Because mechanical strength, magnetic permeability, and saturation magnetization tend to increase, the content (filling rate) of the soft magnetic powder in the magnetic composite material may be 50% by volume or more and less than 100% by volume, 80% by volume or more and less than 100% by volume, 70% by volume or more and 95% by volume or less, or 80% by volume or more and 90% by volume or less. The remainder of the magnetic composite material excluding the soft magnetic powder may be a resin composition. In other words, the content of the resin composition in the magnetic composite material may be greater than 0% by volume and less than 50% by volume, greater than 0% by volume and less than 20% by volume, 5% by volume and less than 30% by volume, or 10% by volume and less than 20% by volume.

[0030] The specific form of the magnetic composite material is not limited. The specific form of the magnetic composite material may be selected depending on the application of the magnetic composite material. For example, the magnetic composite material may be a magnetic paste, a magnetic film (magnetic sheet), or a magnetic powder (compound powder) at room temperature. According to this embodiment, the fluidity of the magnetic paste or magnetic powder suitable for processing, or the flexibility of the magnetic film suitable for processing, is achieved.

[0031] (Details of Soft Magnetic Powder) The soft magnetic powder may contain at least one metal element selected from the group consisting of base metal elements, precious metal elements, transition metal elements, and rare earth elements. For example, the soft magnetic powder may contain at least one metal element selected from the group consisting of iron (Fe), copper (Cu), titanium (Ti), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), tin (Sn), chromium (Cr), barium (Ba), strontium (Sr), lead (Pb), silver (Ag), and niobium (Nb). The soft magnetic powder may contain a non-metal element in addition to a metal element. For example, the non-metal element contained in the soft magnetic powder may be at least one element selected from the group consisting of boron (B), oxygen (O), beryllium (Be), phosphorus (P), carbon (C), and silicon (Si).

[0032] The composition of the submicron particles is not limited as long as the submicron particles are soft magnetic and at least some of the submicron particles are Fe-based alloys. A plurality of the submicron particles may be composed of only one type of Fe-based alloy. A plurality of the submicron particles may include two or more types of Fe-based alloys with different compositions. Some or all of the submicron particles may be crystalline (single crystal or polycrystalline). For example, some or all of the submicron particles may include nanocrystals. A single submicron particle may be composed of one or more nanocrystals. For example, the nanocrystals may be crystals with a grain size or crystallite size of 1 nm or more but less than 1 μm, or 1 nm or more but 100 nm or less. Some or all of the submicron particles may be amorphous. For example, some or all of the submicron particles may be metallic glass.

[0033] The magnetic loss of alloys containing iron and boron tends to be lower than that of other iron-based alloys and ferrite. For example, in the high-frequency band (AC frequency range of 10 MHz to 100 MHz), the tan δ of alloys containing iron and boron tends to be lower than that of ferrite. Therefore, because magnetic loss is easily reduced, at least some or all of the submicron particles may be an Fe—B-based alloy containing iron and boron. Because Fe—B—Ni-based alloys tend to have a higher relative magnetic permeability in the high-frequency band than Fe—B-based alloys, at least some or all of the submicron particles may be an Fe—B—Ni-based alloy containing iron, boron, and nickel. The magnetic composite material may include both an Fe—B-based alloy and an Fe—B—Ni-based alloy as the plurality of submicron particles. Because magnetic loss is easily reduced, the boron content of the submicron particles may be 5 atomic % to 40 atomic %. The nickel content in the submicron particles (Fe—B—Ni-based alloy) may be 15 atomic % or more and 55 atomic % or less because this tends to reduce magnetic loss. However, the submicron particles do not have to contain nickel. When the submicron particles are an Fe-based alloy containing boron (and nickel), the remainder of the submicron particles excluding boron (and nickel) may be iron.

[0034] The submicron particles are not limited to Fe-based alloys containing boron. For example, the plurality of submicron particles may include at least one alloy selected from the group consisting of an Fe—B-based alloy, an Fe—B—Ni-based alloy, an Fe—B—P-based alloy, an Fe—B—Si-based alloy, an Fe—B—Si—Cr-based alloy, an Fe—B—P—Si—Nb—Cr-based alloy, an Fe—Si—Nb—B—Cu-based alloy, an Fe—Cr—Si-based alloy, an Fe—Cr-based alloy, an Fe—Si-based alloy, an Fe—Si—Al-based alloy, an Fe—Ni-based alloy, an Fe—Ni—Cu-based alloy, an Fe—Ni—Cr-based alloy, an Fe—Si—B—C—Cr-based alloy, and an Fe—Co-based alloy.

[0035] The composition of the large particles is not limited as long as they are soft magnetic materials. Multiple large particles may consist of only one type of soft magnetic material. Multiple large particles may contain two or more types of soft magnetic materials with different compositions. Some or all of the large particles may be crystalline (single crystal or polycrystalline). Some or all of the large particles may be amorphous. For example, some or all of the large particles may be metallic glass. The composition of some or all of the large particles may match the composition of some or all of the submicron particles. The composition of some or all of the large particles may be different from the composition of some or all of the submicron particles.

[0036] For example, at least some or all of the large particles may contain at least one selected from the group consisting of ferrite, pure iron, and alloys. For example, the ferrite contained in the large particles may be at least one ferrite selected from the group consisting of spinel ferrite and garnet ferrite. For example, the spinel ferrite may be AFe ２ O ４ AFe may be expressed as ２ O ４ In the formula, A may be one or more elements selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn. For example, the garnet ferrite may be RFe ５ O １２ RFe ５ O １２R in the formula may be one or more rare earth elements. For example, the pure iron contained in the large particles may be carbonyl iron powder. Carbonyl iron powder is represented by the formula Fe(CO) ５ The large particles are spherical pure iron powders obtained by the reduction (thermal decomposition) of iron pentacarbonyl. For example, the alloy contained in the large particles may be at least one alloy selected from the group consisting of an Fe—B alloy, an Fe—B—Ni alloy, an Fe—B—P alloy, an Fe—B—Si alloy, an Fe—B—Si—Cr alloy, an Fe—B—P—Si—Nb—Cr alloy, an Fe—Si—Nb—B—Cu alloy, an Fe—Cr—Si alloy, an Fe—Cr alloy, an Fe—Si alloy, an Fe—Si—Al alloy, an Fe—Ni alloy, an Fe—Ni—Cu alloy, an Fe—Ni—Cr alloy, an Fe—Si—B—C—Cr alloy, an Fe—Co alloy, a Cu—Sn alloy, a Cu—Sn—P alloy, a Cu—Ni alloy, and a Cu—Be alloy.

[0037] The soft magnetic powder may further include soft magnetic particles other than the submicron particles and large particles.

[0038] A part or all of the soft magnetic particles constituting the soft magnetic powder may be covered with an insulating coating. A part or all of the surface of each soft magnetic particle may be covered with an insulating coating. By covering the surface of each soft magnetic particle with an insulating coating, the electrical insulation of the magnetic composite material is improved. When the insulating coating contains glass, the surface of the insulating coating is likely to be smooth, and friction between the soft magnetic particles is likely to be suppressed. As a result, the fluidity of the magnetic composite material is likely to be improved. For example, the insulating coating may be made of glass, phosphate (calcium phosphate, etc.), silica (SiO ２ ), titania (TiO ２ ), iron oxide (Fe ２ O ３ ), and chromium oxide (Cr ２ O ３) In addition to silicon (Si), the glass may contain at least one element selected from the group consisting of oxygen (O), boron (B), sodium (Na), and aluminum (Al). For example, the glass may contain at least one component of silicate glass (silicate), phosphosilicate glass (phosphosilicate), and borosilicate glass (borosilicate).

[0039] For example, the submicron particles and the large particles can be obtained by water atomization, gas atomization, pulverization, or liquid phase synthesis. The particle size distribution of the submicron particles and the large particles can be adjusted using a pulverizer such as a ball mill or a bead mill, an air classifier, a wet sieving machine, or a sieve.

[0040] For example, by the following liquid phase synthesis method (aqueous solution reduction reaction method) described in K. Murata, T. Miyazaki, H. Masumoto, and Y. Endo: Transaction of the Magnetics Society of Japan (Special Issues) Vol. 5, No. 1, 2021, the particle size of submicron particles containing an Fe—B-based alloy or an Fe—B—Ni-based alloy can be easily controlled to 0.1 μm or more and less than 0.5 μm (0.1 μm or more and 0.49 μm or less).

[0041] Purified water is placed in a reaction vessel. Iron (II) sulfide heptahydrate (FeSO ４ ・7H ２ O), ammonium chloride (NH ４ Cl), and trisodium citrate dihydrate (C ６ H ５ Na ３ O ７ ・2H ２ To prepare submicron particles containing an Fe—B—Ni alloy, nickel(II) sulfate hexahydrate (NiSO ) is dissolved in purified water along with iron(II) sulfide heptahydrate. ４ ・6H ２0) is also dissolved in purified water. Furthermore, an aqueous solution of sodium hydroxide (NaOH) is added to the purified water to obtain an Fe-based reaction solution with an adjusted pH. The Fe-based reaction solution may be alkaline. For example, the pH of the Fe-based reaction solution may be 9.

[0042] The Fe-based reaction solution is stirred in the atmosphere and heated by ultrasonic vibration, while an aqueous solution of a B-based reducing agent is added dropwise to the Fe-based reaction solution. For example, the B-based reducing agent is sodium borohydride (NaBH ４ The aqueous solution of the B-based reducing agent is obtained by dissolving the B-based reducing agent in purified water. During the dropwise addition of the aqueous solution of the B-based reducing agent, the temperature of the Fe-based reaction solution is adjusted to 0°C or higher and 50°C or lower. As the aqueous solution of the B-based reducing agent is dropped, submicron particles precipitate in the Fe-based reaction solution. In other words, the Fe in the Fe-based reaction solution ２＋ and B.H. ４ － By the reaction of ２ B) are synthesized into submicron particles.

[0043] The particle size of the submicron particles varies depending on factors such as the dropwise addition rate of the aqueous solution of the B-based reducing agent, the temperature of the Fe-based reaction solution, and the pH of the Fe-based reaction solution. As the dropwise addition rate of the aqueous solution of the B-based reducing agent increases, the particle size of the submicron particles tends to decrease. As the temperature of the Fe-based reaction solution increases, the particle size of the submicron particles tends to increase.

[0044] (Details of Resin Composition) The resin composition contains at least a thermosetting resin. In addition to the thermosetting resin, the resin composition may further contain at least one component selected from the group consisting of a curing agent, a curing accelerator, a coupling agent, a wax, a rubber, and a flame retardant. For example, the content of the resin composition in the magnetic composite material may be 3% by mass or more and 30% by mass or less. In other words, the content of the soft magnetic powder in the magnetic composite material may be 70% by mass or more and 97% by mass or less.

[0045] <Thermosetting Resin> The thermosetting resin is the main component of the resin composition. For example, the thermosetting resin may be at least one resin selected from the group consisting of an epoxy resin, a phenolic resin, a bismaleimide resin, a polyimide resin, and a polyamideimide resin. The resin composition may further contain other resins (e.g., thermoplastic resins) in addition to the thermosetting resin. For example, the resin composition may further contain at least one other resin selected from the group consisting of a polyphenylene sulfide resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, and a silicone resin.

[0046] For example, epoxy resins (epoxy group-containing compounds) include biphenyl-type epoxy resins, stilbene-type epoxy resins, diphenylmethane-type epoxy resins, sulfur-atom-containing epoxy resins, novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, salicylaldehyde-type epoxy resins, naphthol- and phenol-copolymerized epoxy resins, epoxidized aralkyl-type phenolic resins, bisphenol-type epoxy resins, glycidyl ether-type epoxy resins of alcohols, glycidyl ether-type epoxy resins of paraxylylene-modified phenolic resins and / or metaxylylene-modified phenolic resins, glycidyl ether-type epoxy resins of terpene-modified phenolic resins, cyclopentadiene-type epoxy resins, The epoxy resin may be one or more resins selected from the group consisting of epoxy resins, glycidyl ether type epoxy resins of polycyclic aromatic ring-modified phenolic resins, naphthalene type epoxy resins, glycidyl ether type epoxy resins of naphthalene ring-containing phenolic resins, glycidyl ester type epoxy resins, glycidyl type or methylglycidyl type epoxy resins, alicyclic type epoxy resins, halogenated phenol novolac type epoxy resins, ortho-cresol novolac type epoxy resins, hydroquinone type epoxy resins, trimethylolpropane type epoxy resins, polyfunctional epoxy resins having multiple epoxy groups (trifunctional epoxy resins, tetrafunctional epoxy resins, etc.), and linear aliphatic epoxy resins obtained by oxidizing olefin bonds with a peracid such as peracetic acid.

[0047] The epoxy resin may contain a reactive diluent, for example, at least one compound selected from the group consisting of n-butyl glycidyl ether, versatate glycidyl ether, styrene oxide, ethylhexyl glycidyl ether, phenyl glycidyl ether, butylphenyl glycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, diethylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether.

[0048] The epoxy resin may include an epoxy group-containing compound that is liquid at 25° C. An epoxy group-containing compound that is liquid at 25° C. means an epoxy group-containing compound having a viscosity of 200 Pa·s or less at 25° C. For example, the epoxy group-containing compound that is liquid at 25° C. may be one or more compounds selected from bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, bisphenol S type epoxy resins, naphthalenediol type epoxy resins, hydrogenated bisphenol A type epoxy resins, and aminoglycidyl ether type epoxy resins.

[0049] <Curing Agent> Curing agents are classified into curing agents that cure epoxy resins in the temperature range from low temperature to room temperature, and heat-curing curing agents that cure epoxy resins upon heating. For example, curing agents that cure epoxy resins in the temperature range from low temperature to room temperature include aliphatic polyamines, polyaminoamides, and polymercaptans. For example, heat-curing curing agents include aromatic polyamines, acid anhydrides, phenolic resins, phenolic novolac resins, imidazoles, imidazolines, and dicyandiamide (DICY). From the viewpoint of improving the heat resistance (mechanical strength at high temperatures) of the cured product of the magnetic composite material, the curing agent may preferably be a heat-curing curing agent, more preferably a phenolic resin, and even more preferably a phenolic novolac resin. The resin composition may contain one or more curing agents.

[0050] The ratio of the hydroxyl group equivalent of the curing agent to the epoxy equivalent of the epoxy resin may be 0.5 or more and 1.5 or less. In other words, the ratio of the active group (phenolic OH group) in the curing agent that reacts with the epoxy group in the epoxy resin may be 0.5 or more and 1.5 or less equivalents per equivalent of epoxy group in the epoxy resin.

[0051] <Curing Accelerator> The curing accelerator (curing catalyst) is not limited as long as it is a substance that reacts with a thermosetting resin to accelerate the curing of the thermosetting resin. For example, the curing accelerator may be an imidazole such as an alkyl group-substituted imidazole or benzimidazole. The curing accelerator may be an imidazoline. The curing accelerator may be a phosphorus compound. The curing accelerator may be a urea compound. The curing accelerator may be a tertiary amine. The resin composition may contain one or more types of curing accelerators.

[0052] The amount of the curing accelerator is not particularly limited. For example, from the viewpoint of improving the curability and fluidity of the epoxy resin when absorbing moisture, the amount of the curing accelerator may be 0.1 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the epoxy resin. The content of the curing accelerator may be 0.001 parts by mass or more and 5 parts by mass or less relative to the total mass of the epoxy resin and the curing agent (e.g., phenolic resin).

[0053] <Coupling Agent> The coupling agent may be a substance that reacts with the glycidyl group of a thermosetting resin such as an epoxy resin. The coupling agent improves the adhesion between the soft magnetic powder and the resin composition, and improves the mechanical strength of the cured product of the magnetic composite material. The coupling agent that reacts with the glycidyl group may be a silane-based compound (silane coupling agent). For example, the silane coupling agent may be at least one coupling agent selected from the group consisting of epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane, acid anhydride silane, and vinyl silane. The resin composition may contain one or more types of coupling agents.

[0054] <Wax> Wax may be referred to as a lubricant or a mold release agent. Wax improves the flowability and moldability of the magnetic composite material, as well as the mold releasability of the magnetic composite material. For example, the wax may be at least one compound selected from saturated fatty acids (such as stearic acid, lauric acid, and montanic acid), saturated fatty acid salts (such as metal soaps), and saturated fatty acid esters. The wax may also be a synthetic wax such as polyethylene and polyethylene oxide. The resin composition may contain one or more types of wax.

[0055] <Rubber> The rubber (elastomer) improves the flexibility of a molded body (e.g., a magnetic film) formed from the magnetic composite material and the flexibility of a cured product of the molded body. For example, the rubber component may be at least one rubber selected from the group consisting of acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, butadiene rubber, acrylonitrile butadiene rubber, silicone rubber, urethane rubber, chloroprene rubber, ethylene propylene rubber, fluororubber, vulcanized rubber, epichlorohydrin rubber, and chlorinated butyl rubber. The resin composition may contain one or more rubber components.

[0056] <Flame Retardant> The magnetic composite material may contain a flame retardant. For example, the flame retardant may be at least one compound selected from the group consisting of a bromine-based flame retardant, a phosphorus-based flame retardant, a hydrated metal compound-based flame retardant, a silicone-based flame retardant, a nitrogen-containing compound, a hindered amine compound, an organometallic compound, and an aromatic engineering plastic. The resin composition may contain one or more flame retardants.

[0057] (Method for producing magnetic composite material and cured product) The magnetic composite material may be obtained by kneading the soft magnetic powder and each component constituting the resin composition while heating. For example, the kneading means for the soft magnetic powder and the resin composition may be a kneader, a roll, or a stirrer.

[0058] A magnetic paste may be obtained by using an organic solvent or an epoxy group-containing compound that is liquid at 25°C as a raw material kneaded with the soft magnetic powder. A magnetic film may be obtained by drying (and curing) the magnetic paste applied to the surface of the support. For example, the organic solvent may be at least one solvent selected from the group consisting of acetone, methyl ethyl ketone (2-butanone), methyl isobutyl ketone (4-methyl-2-pentanone), benzene, toluene, xylene, carbitol acetate, butyl carbitol acetate, cyclohexanone, and N-methyl-2-pyrrolidone (NMP). For example, the support may be a polymer film that is heat-resistant and solvent-resistant. For example, the polymer film may be a polyester such as polyethylene terephthalate (PET) or a polyolefin such as polypropylene or polyethylene. For example, the support may be a metal foil such as copper foil.

[0059] A lump of mixed powder (agglomerated mixed powder) may be obtained by heating and kneading the soft magnetic powder and the resin composition, and a magnetic powder (compound powder) may be obtained by pulverizing the lump of mixed powder. For example, a mixture may be obtained by kneading the soft magnetic powder, the resin composition, and the organic solvent while heating, and the magnetic powder may be obtained by drying and pulverizing the mixture. A mixed liquid may be obtained by mixing the soft magnetic powder and the resin composition in an organic solvent, and the magnetic powder may be obtained by drying the mixed liquid.

[0060] The kneading time depends on the kneading means, the volume of the kneading means, and the amount of magnetic composite material produced. The kneading time is not limited. For example, the kneading time may be 1 minute or more and 20 minutes or less. For example, the temperature (heating temperature) of the soft magnetic powder and resin composition during kneading may be lower than the thermosetting temperature of the thermosetting resin. The heating temperature may be a temperature at which a semi-cured product of the thermosetting resin (a B-stage resin composition) is produced and the production of a cured product of the thermosetting resin (a C-stage resin composition) is suppressed. The heating temperature may be a temperature lower than the activation temperature of the curing accelerator. For example, the heating temperature may be 50°C or more and 150°C or less.

[0061] A compact may be obtained by molding the magnetic composite material. Heat treatment of the compact (thermal curing of the resin composition in the compact) causes the soft magnetic powder to be firmly bound to each other by the cured resin composition, resulting in a cured magnetic composite material. For example, the molding method for the magnetic composite material may be transfer molding, extrusion molding, or compression molding (powder compaction). The dimensions and shape of the mold used to mold the magnetic composite material may be selected depending on the industrial product manufactured using the magnetic composite material. The heat treatment temperature of the compact may be a temperature at which the resin composition in the compact is sufficiently cured, and may be equal to or higher than the activation temperature of the curing accelerator. For example, the heat treatment temperature may be 100°C or higher and 300°C or lower. For example, the heat treatment time may be several minutes or longer and 10 hours or shorter. To suppress oxidation of the soft magnetic powder in the compact, the heat treatment of the compact may be performed in an inert atmosphere.

[0062] (Method of Analyzing Magnetic Composite Material) For example, the soft magnetic powder contained in the magnetic composite material may be analyzed and identified by one or more analytical methods selected from the group consisting of X-ray fluorescence analysis (XRF), inductively coupled plasma (ICP) emission spectroscopy, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS or EDX), and mass spectrometry (MS). For example, each component of the resin composition (such as a thermosetting resin) contained in the magnetic composite material may be analyzed and identified by one or more analytical methods selected from the group consisting of infrared spectroscopy (IR), nuclear magnetic resonance (NMR), gas chromatography (GC), high performance liquid chromatography (HPLC), and mass spectrometry. When a cured product of the magnetic composite material (an industrial product using the magnetic composite material) is analyzed, the composition of the magnetic composite material itself may be analyzed retrospectively by analyzing a sample obtained by pulverizing the cured product. The sample may be dissolved in an organic solvent, and the soft magnetic powder may be separated from the resin composition dissolved in the organic solvent. The soft magnetic powder and the resin composition separated from each other may be analyzed individually. Even when an unused magnetic composite material itself is directly analyzed, the soft magnetic powder and the resin composition separated from each other by the above method may be analyzed individually.

[0063] (Applications of Magnetic Composite Material) For example, specific industrial products manufactured using the magnetic composite material may be inductors, power supply modules, transformers, reactors, thyristor valves, noise filters (EMI filters), choke coils, motors (cores, rotors, and yokes), electromagnetic wave shields, and solenoid cores (stationary iron cores) for electromagnetic valves incorporated into electronically controlled fuel injection devices for internal combustion engines.

[0064] For example, the magnetic composite material may be used in a powder magnetic core (a magnetic core arranged inside a coil) included in a coil component such as an inductor. The magnetic composite material may also be used as a sealing material in which a coil is embedded. The magnetic composite material can combine the electrical insulation required for a sealing material for electronic devices with the soft magnetic properties (electromagnetic wave shielding ability) required for an electromagnetic wave shielding material. Therefore, the magnetic composite material and its cured product may be used in electronic components or electrical devices as a sealing material that also serves as an electromagnetic wave shielding material. For example, the sealing material that also serves as an electromagnetic wave shielding material may be a sealing material (such as an underfill) for semiconductor packages such as IC packages and LSI packages.

[0065] The present disclosure is not necessarily limited to the above-described embodiments. Various modifications of the present disclosure are possible without departing from the spirit of the present disclosure, and these modifications are also included in the present disclosure.

[0066] The present disclosure will be described in detail with reference to the following examples and comparative examples, but the technical scope of the present disclosure is not limited to the following examples.

[0067] Example 1 Preparation of Resin Composition (Varnish) A liquid resin composition (varnish) was prepared by stirring and kneading 24.0 g of solvent, 27.0 g of thermosetting resin, 10.8 g of curing agent, 0.258 g of curing accelerator, and 110.0 g of elastomer component using a planetary stirrer. The non-volatile content (NV) of the varnish was approximately 30.1%. Cyclohexanone manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. was used as the solvent. Biphenyl aralkyl epoxy resin (NC-3000H) manufactured by Nippon Kayaku Co., Ltd. was used as the thermosetting resin. ＴＭ The curing agent used was a phenol novolak resin (HP-850N manufactured by Resonac Co., Ltd.). ＴＭ ) was used as a curing accelerator. ＴＭ The elastomer component used was epoxy group-containing acrylic rubber (HTR-860P-3 manufactured by Nagase ChemteX Corporation). ＴＭThe content of nonvolatile components (NV) in the elastomer component was 12% (13.75 g).

[0068] As the soft magnetic powder of Example 1, a powder consisting of a large number of submicron particles 1 and a powder consisting of a large number of large particles 1 were used. The submicron particles 1 were produced by the aqueous solution reduction reaction method described above. The submicron particles 1 were an Fe-based alloy consisting of Fe and B. The median diameter D50 of the submicron particles 1 was 0.2 μm. The large particles 1 were an Fe-Si-B-P-Nb-Cr-based alloy (SAP-2DC) manufactured by Shinto Kogyo Co., Ltd. ＴＭ The median diameter D50 of large particles 1 was 2.2 μm. Large particles 1 were metallic glass, and the surfaces of large particles 1 were covered with an insulating coating.

[0069] Submicron particles 1, large particles 1, and the resin composition were stirred and kneaded using a planetary stirrer to obtain the magnetic paste (liquid magnetic composite material) of Example 1. The mass (unit: g) and content (unit: volume %) of each of submicron particles 1, large particles 1, and the resin composition (non-volatile components) in the magnetic composite material were adjusted to the values ​​shown in Table 1 below.

[0070] <Measurement of complex relative permeability and magnetic loss coefficient> The magnetic paste was applied to a support (PET film) using a squeegee and dried at 120°C for 20 minutes to form a magnetic film A. In other words, a laminate consisting of a support and a magnetic film A covering the surface of the support was obtained. Multiple magnetic films A peeled from the laminate were stacked using a vacuum laminator to obtain a magnetic film B. The thickness of the magnetic film B was approximately 1.1 mm. 1 mm thick stainless steel plates were placed on all four sides of the magnetic film B, surrounding the magnetic film B with the stainless steel plates. The magnetic film B surrounded by the stainless steel plates was heated and pressurized in a vacuum press for 60 minutes to obtain a plate made of a cured magnetic composite material. The thickness of the plate was 1 mm. The temperature of the magnetic film B during pressurization was 180°C. The pressure applied to the magnetic film B during heating was 2 MPa. The vacuum press used was a manual hydraulic vacuum heating press 1A31 manufactured by Imoto Machinery Co., Ltd. ＴＭA toroidal (annular) sample was obtained by cutting a plate made of a cured magnetic composite material with a drill. The outer diameter of the sample was 20 mm, the inner diameter of the sample was 5 mm, and the thickness of the sample was 1 mm.

[0071] The complex relative permeability of a toroidal sample (a cured product of a magnetic composite material) was measured at room temperature. The complex permeability was measured by the S-parameter method using a vector network analyzer (VNA). A coaxial tube having a structure and dimensions capable of fitting a toroidal sample was connected to the VNA, and the impedance was first measured without the sample. Next, the impedance was measured with the sample fitted into the coaxial tube. The AC frequency during impedance measurement in each state was 20 MHz. Based on the dimensions of the coaxial tube and the sample, and the change in impedance depending on the presence or absence of the sample, the complex relative permeability of the sample, the imaginary part μ″ of the complex relative permeability, the real part μ′ of the complex relative permeability, and the magnetic loss factor tanδ (i.e., μ″ / μ′) were calculated. μ′ (unit: no) and tanδ (unit: no) for Example 1 are shown in Table 1 below. A high μ′ is preferable, and a low tanδ is preferable.

[0072] <Measurement of Saturation Magnetization> As in the measurement of complex relative permeability, a plate made of a cured magnetic composite material was used to measure saturation magnetization. The method for preparing the plate made of a cured magnetic composite material was as described above. A square sample was cut out of the plate made of the cured magnetic composite material by cutting with a drill. The dimensions of the square sample were 8 mm long x 8 mm wide x 1 mm thick. The saturation magnetization Ms of the square sample was measured using a vibrating sample magnetometer (VSM). During the measurement of saturation magnetization Ms, the strength of the magnetic field applied to the sample was changed within a range of -1000 kA / m to +1000 kA / m, and a magnetization curve was obtained. The magnetization value in the magnetic field region where the magnetization value of the sample was saturated on the magnetization curve was the saturation magnetization Ms. The saturation magnetization Ms (unit: kA / m) of Example 1 is shown in Table 1 below. It is preferable that the saturation magnetization Ms is high.

[0073] <Measurement of Tensile Strength> The magnetic paste of Example 1 was applied to a PET film and dried at 120°C for 20 minutes to form a magnetic film. A sheet of cured magnetic composite material was obtained by heating the magnetic film peeled from the PET film. The sheet had a thickness of 40 μm. Dumbbell-shaped samples (dumbbell No. 1) were cut from the sheet. The tensile strength (tensile strength at break) of the dumbbell-shaped samples was measured at 23°C in accordance with Japanese Industrial Standard JIS K7127. In measuring tensile strength, the load pulling the sample in its longitudinal direction gradually increases. The tensile strength corresponds to the load acting on the sample at the moment of breakage. Tensile strength was measured using a tensile tester RTC-1250A manufactured by A&D Manufacturing Co., Ltd. (formerly Orientec Co., Ltd.). ＴＭ was used. The average value of the tensile strength was calculated from the results of three measurements. The average value of the tensile strength (unit: MPa) of Example 1 is shown in Table 1 below. It is preferable that the tensile strength (i.e., mechanical strength) is high.

[0074] (Examples 2 to 5 and Comparative Examples 1 to 3) In Examples 2, 4, and 5 and Comparative Examples 1 to 3, large particles 2 were used instead of large particles 1. Large particles 2 were made of an Fe—Si—Nb—B—Cu alloy (ATFINE-NC1) manufactured by Epson Atmix Corporation. ＴＭ The median diameter D50 of large particles 2 was 3.1 μm. Large particles 2 were particles made of nanocrystals.

[0075] In Example 3, large particles 3 were used instead of large particles 1. Large particles 3 were made of an Fe—Si—B—C—Cr alloy (AW2-08) manufactured by Epson Atmix Corporation. ＴＭ The median diameter D50 of large particles 3 was 3.3 μm. Large particles 3 were an amorphous alloy.

[0076] In Comparative Example 3, submicron particles 2 were used instead of submicron particles 1. Submicron particles 2 were manganese ferrite (M001) manufactured by Powder Tech Co., Ltd. ＴＭ ) In other words, the submicron particles 2 were metal oxides and not alloys containing iron. The median diameter D50 of the submicron particles 2 was 0.1 μm.

[0077] In Examples 2 to 5 and Comparative Examples 1 to 3, the mass (unit: g) and content (unit: vol%) of each of the submicron particles, large particles, and resin composition (non-volatile component) in the magnetic composite material were adjusted to the values ​​shown in Table 1 below.

[0078] Except for the above-mentioned points, magnetic pastes (magnetic composite materials) for each of Examples 2 to 5 and Comparative Examples 1 to 3 were prepared in the same manner as in Example 1. Measurements were carried out using samples for each of Examples 2 to 5 and Comparative Examples 1 to 3 in the same manner as in Example 1. The μ', tan δ, Ms and tensile strength for each of Examples 2 to 5 and Comparative Examples 1 to 3 are shown in Table 1 below.

[0079]

[0080] For example, the magnetic composite material according to one aspect of the present disclosure may be used as a raw material for coil components such as inductors.

Claims

1. A magnetic composite material comprising a soft magnetic powder and a resin composition, wherein the soft magnetic powder comprises a plurality of submicron particles and a plurality of large particles having a particle size larger than that of the submicron particles, the resin composition comprises a thermosetting resin, at least a portion of the submicron particles are an alloy containing iron, the content of the submicron particles in the magnetic composite material is expressed as V1 vol%, the content of the large particles in the magnetic composite material is expressed as V2 vol%, and V2 / V1 is equal to or greater than 1.0 and less than 28.

0.

2. The magnetic composite material according to claim 1, wherein the large particles have a particle size of 5.0 μm or less.

3. The magnetic composite material according to claim 1, wherein the large particles have a particle size of 2.5 μm or less.

4. The magnetic composite material of claim 1, wherein at least some of the large particles comprise at least one selected from the group consisting of ferrite, pure iron, and alloys.

5. The magnetic composite material of claim 1, wherein at least some of the submicron particles are an alloy containing iron and boron.

6. The magnetic composite material of claim 1, wherein at least some of the submicron particles are an alloy containing iron, boron, and nickel.

7. The magnetic composite material according to claim 6, wherein the content of nickel in the submicron particles is 15 atomic % or more and 55 atomic % or less.

8. The magnetic composite material of claim 1, wherein at least some of the submicron particles comprise nanocrystals.

9. The magnetic composite material according to claim 1, wherein the content of the soft magnetic powder in the magnetic composite material is 50% by volume or more and less than 100% by volume.

10. The magnetic composite material according to claim 1, wherein the content of the soft magnetic powder in the magnetic composite material is 80% by volume or more and less than 100% by volume.

11. The magnetic composite material according to claim 1, wherein the particle size of the submicron particles is 0.1 μm or more and less than 0.5 μm.

12. The magnetic composite material according to any one of claims 1 to 11, which is a magnetic paste.

13. The magnetic composite material according to any one of claims 1 to 11, which is a magnetic film.

14. The magnetic composite material according to any one of claims 1 to 11, which is a magnetic powder.

15. A cured product of the magnetic composite material according to any one of claims 1 to 11.

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