Compound, molded body, cured product of compound, magnetic core, and coil component

Abstract

Provided is a compound that has a metal powder content of 96.5 mass% or more, has outstanding fluidity, and increases the mechanical strength at high temperatures (e.g., 150°C or higher) of a molded body containing the compound uncured or semi-cured. The compound contains a metal powder and a resin composition. The metal powder is a soft magnetic material. The resin composition contains an epoxy resin and a curing agent. The curing agent contains a triphenylmethane-type phenol resin and a phenol novolac resin. The metal powder content in the compound is 96.5-98.0 mass%. The resin composition content in the compound is 2.0-3.5 mass%. The mass ratio of the triphenylmethane-type phenol resin and the phenol novolac resin to 100 parts by mass of the epoxy resin is 47.0-63.0 parts by mass.

Description

Compounds, molded products, cured compound products, magnetic cores, and coil components

[0001] This disclosure relates to compounds, molded articles, cured products of compounds, magnetic cores, and coil components.

[0002] Compounds containing soft magnetic metal powder and electrically insulating resin compositions (such as thermosetting resins) are used as raw materials for various industrial products. (See Patent Documents 1 to 5 below.) For example, compounds are used as raw materials for inductors, reactors, transformers, motor stators, motor yokes, power modules, thyristor valves, noise filters (EMI filters), choke coils, and solenoid cores. Compounds are also used as encapsulants for electronic equipment such as semiconductors or electronic circuit boards.

[0003] Japanese Patent Publication No. 2020-174179, Japanese Patent Publication No. 6526471, International Publication No. 2020 / 213500, Japanese Patent Publication No. 7168131, Japanese Patent Publication No. 6812091

[0004] In the manufacture of various industrial products that use compounds as raw materials, compound molding (e.g., transfer molding) is necessary. Compound molding requires fluidity. If the compound has poor fluidity, it is difficult to supply and fill the mold evenly, making compound molding difficult, and it becomes difficult to precisely adjust the shape and dimensions of industrial products (e.g., coil components such as inductors) based on the shape and dimensions of the mold. However, since metal powders tend to aggregate, the fluidity of the compound deteriorates as the metal powder content (unit: mass%) in the compound increases. On the other hand, the electromagnetic performance of coil components (e.g., relative permeability or inductance value) improves as the metal powder content in the compound increases. Therefore, improvement in compound fluidity is required, especially when the metal powder content in the compound is high.

[0005] In the manufacture of various industrial products that use compounds as raw materials, molded bodies containing uncured or semi-cured compounds are processed at high temperatures (e.g., the thermosetting temperature of thermosetting resins). To suppress damage to the molded body due to high-temperature processing, the mechanical strength of the molded body at high temperatures is required. For example, in the manufacture of coil components such as inductors, uncured compound (primary material) is supplied into a mold in which the coil is placed. The compound (primary material) fills the inside of the coil, and the entire coil is covered with the compound (primary material). As a result, a molded body is formed in which the coil is sealed in uncured or semi-cured compound (primary material). The coil is exposed on the surface of the molded body by scraping the surface. Furthermore, uncured compound (secondary material) is supplied into the mold in which the molded body is placed, and the surface of the molded body is covered with the compound (secondary material). The molded body covered with compound (secondary material) is heated and pressurized at a high temperature (e.g., 150°C) by the mold. As a result, a molded body consisting of a coil and a semi-cured compound (primary and secondary material) is obtained. Further heating of the molded body consisting of the coil and the semi-cured compound completely cures the compound in the molded body.

[0006] As described above, molded articles containing uncured or semi-cured compound (primary material) are heated and pressurized at high temperatures (e.g., 150°C), so high mechanical strength at high temperatures is required for molded articles containing uncured or semi-cured compound (primary material). However, the mechanical strength of molded articles containing uncured or semi-cured compound decreases as the metal powder content in the compound increases. On the other hand, the electromagnetic performance of coil components (e.g., relative permeability or inductance value) improves as the metal powder content in the compound increases. Therefore, especially when the metal powder content in the compound is high, improved high-temperature mechanical strength of molded articles containing uncured or semi-cured compound is required.

[0007] One aspect of this disclosure is to provide a compound having a metal powder content of 96.5% by mass or more, excellent fluidity, and increasing the mechanical strength of a molded article containing an uncured or semi-cured compound at high temperatures (for example, 150°C or higher), a molded article containing the compound, a cured product of the compound, a magnetic core containing the cured product of the compound, and a coil component containing the cured product of the compound.

[0008] For example, one aspect of this disclosure relates to a compound as described in any one of the following [1] to [3], a molded article as described in [4], a cured product of the compound as described in [5], a magnetic core as described in [6], and a coil component as described in [7] or [8].

[0009] [1] A compound comprising a metal powder and a resin composition, wherein the metal powder is a soft magnetic material, the resin composition comprises an epoxy resin and a curing agent, the curing agent comprises a triphenylmethane-type phenolic resin and a phenol novolac resin, the content of the metal powder in the compound is 96.5% by mass or more and 98.0% by mass or less, the content of the resin composition in the compound is 2.0% by mass or more and 3.5% by mass or less, and the mass ratio of the triphenylmethane-type phenolic resin and the phenol novolac resin to 100 parts by mass of the epoxy resin is 47.0 parts by mass or more and 63.0 parts by mass or less.

[0010] [2] The epoxy resin is the compound according to [1], wherein the epoxy resin comprises a trisphenolmethane type epoxy resin.

[0011] [3] The compound described in [1] or [2], which is a raw material for the magnetic core.

[0012] [4] A molded article comprising the compound described in any one of items [1] to [3].

[0013] [5] A cured compound according to any one of items [1] to [3].

[0014] [6] A magnetic core containing the cured material described in [5].

[0015] [7] A coil component comprising the magnetic core described in [6] and a coil, wherein the magnetic core is disposed inside the coil.

[0016] [8] A coil component comprising the cured product described in [5], and a coil, wherein the coil is sealed within the cured product.

[0017] According to one aspect of this disclosure, a compound is provided which has a metal powder content of 96.5% by mass or more, has excellent fluidity, and enhances the mechanical strength of a molded article containing an uncured or semi-cured compound at high temperatures (for example, 150°C or higher), a molded article containing the compound, a cured product of the compound, a magnetic core containing the cured product of the compound, and a coil component containing the cured product of the compound.

[0018] Figure 1 is a schematic perspective view of a specific example of a coil component (inductor). Figure 2 is a schematic cross-sectional view of the coil component shown in Figure 1, and the cross-section shown in Figure 2 includes the central axis of the coil and crosses the pair of terminal electrodes that the coil component has.

[0019] Preferred embodiments of the present disclosure will be described below with reference to the drawings. In the drawings, equivalent components are denoted by equivalent reference numerals. The present disclosure is not limited to the embodiments described below. In the present disclosure, relative permeability means both the relative permeability of the compound and the relative permeability of the cured product of the compound (e.g., the magnetic core).

[0020] (Overview of Compound, Molded Article, Cured Compound, Magnetic Core, and Coil Component) The compound according to this embodiment comprises a metal powder and an uncured resin composition. The compound may be solid at room temperature (e.g., 20 ± 15°C). For example, the compound may be a powder or tablet at room temperature. The metal powder and resin composition in the compound may be mixed. In other words, the compound may be rephrased as a mixture containing the metal powder and the resin composition. The compound may consist only of the metal powder and the resin composition. The compound may further contain other components in addition to the metal powder and the resin composition. For example, the compound may be a paste further containing an organic solvent in addition to the metal powder and the resin composition.

[0021] Metal powder consists of multiple metal particles. Metal powder is a soft magnetic material. Metal powder can also be described as a metal filler.

[0022] The surface of some or all of the multiple metal particles constituting the metal powder may be covered with a resin composition. The compound may contain one or more metal particles that are not covered with a resin composition. The compound may contain one or more particles consisting solely of a resin composition. The compound may contain one or more composite particles (granules) consisting of one or more metal particles constituting the metal powder and a resin composition covering one or more metal particles. One composite particle may consist of multiple metal particles bound together via a resin composition.

[0023] The molded article according to this embodiment includes an uncured or semi-cured compound. That is, the molded article may include one or both of the uncured resin composition (uncured resin composition) and the semi-cured resin composition (semi-cured resin composition, i.e., B-stage resin composition). The molded article according to this embodiment may consist only of an uncured or semi-cured compound. In addition to the uncured or semi-cured compound, the molded article may include other components such as coils. The cured compound according to this embodiment includes a cured resin composition (C-stage resin composition). In a molded article containing a compound, or a cured compound, the resin composition or its cured product binds a plurality of metal particles together. Since the resin composition has electrical insulating properties, the resin composition or its cured product interposed between a plurality of adjacent metal particles electrically insulates the plurality of metal particles. Furthermore, the resin composition or its cured product interposed between a plurality of adjacent metal particles suppresses magnetic saturation of the compound or its cured product and suppresses a decrease in relative permeability.

[0024] For example, the compound may be the raw material for a coil component. For example, the coil component may include a cured compound and a coil. For example, the compound may be the raw material for a magnetic core (e.g., a compacted magnetic core) included in the coil component. That is, the magnetic core may include a cured compound. The magnetic core may consist only of a cured compound. The structure of the coil component is not limited. For example, as shown in Figures 1 and 2, the coil component 1 (e.g., an inductor) may include a cured compound 2 and a coil 5, the coil 5 may be sealed in the cured compound 2, and the magnetic core 2dc containing the cured compound 2 may be arranged inside the coil 5. The coil component 1 may further include a pair of terminal electrodes 3, one of which may be located on one end face of the coil component 1 and the other terminal electrode 3 on the other end face of the coil component 1. One end of the coil 5 (the lead-out portion 5a) may be connected to one terminal electrode 3, and the other end of the coil 5 (the lead-out portion 5b) may be connected to the other terminal electrode 3.

[0025] The resin composition comprises an epoxy resin and a curing agent. The epoxy resin is a thermosetting resin. The resin composition may be described as a thermosetting binder (adhesive). The curing agent comprises a triphenylmethane-type phenolic resin and a phenol novolac resin. In other words, the triphenylmethane-type phenolic resin and the phenol novolac resin cure the resin composition upon heating. For example, the epoxy groups (glycidyl groups) in the epoxy resin react with the hydroxyl groups contained in the triphenylmethane-type phenolic resin and the phenol novolac resin, respectively, upon heating of the resin composition. As a result, multiple epoxy resin molecules are crosslinked by multiple triphenylmethane-type phenolic resin molecules and multiple phenol novolac resin molecules. In other words, multiple crosslinked structures are formed between multiple epoxy resin molecules via multiple curing agent molecules, and the resin composition is cured. The compound may contain either or both of the uncured resin composition and the semi-cured resin composition (stage B resin composition).

[0026] Among the various conventional curing agents (phenol resins), triphenylmethane-type phenol resins have a relatively low viscosity. Therefore, triphenylmethane-type phenol resins reduce the viscosity of compounds, and compounds containing triphenylmethane-type phenol resins are more fluid. Both triphenylmethane-type phenol resins and phenol novolac resins are polyfunctional curing agents with a relatively large number of hydroxyl groups per molecule. In other words, among the various conventional curing agents (phenol resins), the hydroxyl group equivalents (g / mol) of triphenylmethane-type phenol resins and phenol novolac resins are relatively small. Therefore, when a molded article containing an uncured or semi-cured compound is heated at a high temperature (for example, a temperature of 150°C or higher), triphenylmethane-type phenol resins and phenol novolac resins increase the density of the crosslinked structure formed in the compound and raise the glass transition temperature Tg of the compound. For example, the glass transition temperature Tg of a compound containing triphenylmethane-type phenolic resin and phenol novolac resin can reach temperatures higher than 150°C. For these reasons, triphenylmethane-type phenolic resin and phenol novolac resin enhance the mechanical strength of a molded article containing an uncured or semi-cured compound at high temperatures (e.g., temperatures of 150°C or higher). "Mechanical strength of a molded article containing an uncured or semi-cured compound at high temperatures (e.g., temperatures of 150°C or higher)" can be rephrased as the mechanical strength of the molded article when the heated molded article reaches a high temperature (e.g., a temperature of 150°C or higher). In other words, at least a portion of the resin composition in the compound contained in the molded article may be semi-cured or cured during the heating process until the compound reaches a high temperature (e.g., a temperature of 150°C or higher). For example, high temperature may be between 150°C and 180°C.

[0027] The mass ratio (<tri-nov>) of triphenylmethane-type phenolic resin and phenol novolac resin to 100 parts by mass of epoxy resin is 47.0 parts by mass or more and 63.0 parts by mass or less, or 47.2 parts by mass or more and 62.2 parts by mass or less. In other words, the mass of epoxy resin is expressed as Me (unit: grams), the mass of triphenylmethane-type phenolic resin is expressed as Mtri (unit: grams), and the mass of phenol novolac resin is expressed as Mnov (unit: grams). The mass ratio (<tri-nov>) of triphenylmethane-type phenolic resin and phenol novolac resin to 100 parts by mass of epoxy resin is defined as {(Mtri + Mnov) / Me} × 100, and <tri-nov> is 47.0 parts by mass or more and 63.0 parts by mass or less, or 47.2 parts by mass or more and 62.2 parts by mass or less. According to the inventors' research, when <tri-nov> is 47.0 parts by mass or more and 63.0 parts by mass or less, the fluidity of the compound is easily improved, and the high-temperature mechanical strength of the molded article containing the uncured or semi-cured compound is easily increased. When <tri-nov> is less than 47.0 parts by mass, the fluidity of the compound deteriorates, and the high-temperature mechanical strength of the molded article containing the uncured or semi-cured compound decreases. For the reasons that the fluidity of the compound is easily improved and the high-temperature mechanical strength of the molded article containing the uncured or semi-cured compound is easily increased, the mass ratio of triphenylmethane-type phenolic resin to 100 parts by mass of epoxy resin (i.e., (Mtri / Me) × 100) may be 4.9 parts by mass or more and 32.1 parts by mass or less. For the reasons that the fluidity of the compound is easily improved and the mechanical strength of the molded article containing the uncured or semi-cured compound at high temperatures is easily increased, the mass ratio of phenol novolac resin to 100 parts by mass of epoxy resin (i.e., (Mnov / Me) × 100) may be 27.3 parts by mass or more and 45.7 parts by mass or less.

[0028] The metal powder content in the compound is 96.5% by mass or more and 98.0% by mass or less, and the resin composition content in the compound is 2.0% by mass or more and 3.5% by mass or less. The metal powder content in the compound may be 96.5% by mass or more and 97.3% by mass or less, and the resin composition content in the compound may be 2.7% by mass or more and 3.5% by mass or less. The metal powder content in the compound may be 96.5% by mass or more and 97.0% by mass or less, and the resin composition content in the compound may be 3.0% by mass or more and 3.5% by mass or less. The higher the metal powder content in the compound, the higher the relative permeability. In other words, the lower the resin composition content in the compound, the higher the relative permeability. The lower the metal powder content in the compound, the more fluid the compound is, and the higher the mechanical strength of the cured compound. In other words, the higher the content of the resin composition in the compound, the more fluid the compound becomes, and the higher the mechanical strength of the cured compound. Conventional compounds with a metal powder content of 96.5% by mass or more have poor fluidity. In contrast, despite having a metal powder content of 96.5% by mass or more in the compound according to this disclosure, the compound is fluid. This is because the compound according to this disclosure contains a triphenylmethane-type phenolic resin. Molded articles containing conventional compounds with a metal powder content of 96.5% by mass or more have poor mechanical strength at high temperatures. In contrast, despite having a metal powder content of 96.5% by mass or more in the compound according to this disclosure, the mechanical strength of molded articles containing the compound according to this disclosure tends to increase at high temperatures. This is because the compound according to this disclosure contains a triphenylmethane-type phenolic resin and a phenol novolac resin.

[0029] For example, the content of each of the metal powder and the resin composition in the compound may be specified by the following method based on the specific gravity of each of the compound, the metal powder, and the resin composition. The specific gravity (unit: none) may be the ratio of the density of each of the compound, the metal powder, and the resin composition to the density of a standard substance (for example, the density of water at 4°C). For example, the specific gravity of each of the compound, the metal powder, and the resin composition may be measured by a general method (such as the water displacement method) based on Archimedes' principle. The specific gravity of each of the metal powder and the resin composition may be measured in advance before the production of the compound. Using an inert organic solvent that does not react with the metal powder and the resin composition, the compound may be separated into the metal powder and the resin composition (organic substances dissolved in the organic solvent), and the specific gravity of each of the separated metal powder and resin composition may be measured. The specific gravity of the metal powder is S Ｍ may be represented as such. The content of the metal powder in the compound may be represented as α mass%. The specific gravity of the resin composition is S Ｒ may be represented as such. The content of the resin composition in the compound may be represented as (100 - α) mass%. The specific gravity S Ｃ of the compound may be represented by the following formula 1. Based on the following formula 1, the content α of the metal powder in the compound may be calculated from the measured specific gravities (S Ｍ , S Ｒ , and S Ｃ ). S Ｃ = [(S Ｍ ×α) + {S Ｒ ×(100 - α)}] / 100 (1)

[0030] (Specific examples of metal powder) For example, the average particle size or D50 (median diameter) of the metal powder (a plurality of metal particles) may be 0.1 μm or more and 45 μm or less.

[0031] The metal powder (multiple metal particles) may contain multiple types of metal powders with different particle sizes. For example, the metal powder may contain a first soft magnetic powder (multiple first soft magnetic particles) and a second soft magnetic powder (multiple second soft magnetic particles), and the particle size of the first soft magnetic powder may be larger than that of the second soft magnetic powder. For example, the average particle size of the first soft magnetic powder may be larger than the average particle size of the second soft magnetic powder. For example, the D50 (median diameter) of the first soft magnetic powder may be larger than that of the second soft magnetic powder. For example, the D90 of the first soft magnetic powder may be larger than that of the second soft magnetic powder. If the compound contains only first soft magnetic powder with a large particle size as the metal powder, gaps are easily formed between multiple adjacent first soft magnetic particles, making it difficult to increase the packing density of the metal powder in the compound. On the other hand, when the compound contains a first soft magnetic powder and a second soft magnetic powder as metal powder, the second soft magnetic particles, which are smaller than the first soft magnetic particles, fill the gaps between the multiple first soft magnetic particles, increasing the packing density of the metal powder in the compound. In other words, the specific gravity of the compound increases because the compound contains a first soft magnetic powder and a second soft magnetic powder with different particle sizes. As a result, the relative permeability improves. Furthermore, as the packing density of the metal powder in the compound increases, the cured compound becomes denser, improving the relative permeability and mechanical strength of the cured compound. For example, the average particle size or D50 of the first soft magnetic powder may be 11 μm or more and 45 μm or less. For example, the average particle size or D50 of the second soft magnetic powder may be 0.1 μm or more and 9.0 μm or less. When the average particle size or D50 of the first soft magnetic powder is within the above range, and the average particle size or D50 of the second soft magnetic powder is within the above range, the filling density of the metal powder in the compound tends to increase, and the relative permeability and mechanical strength tend to increase.

[0032] The mass of the first soft magnetic powder may be expressed as M1, and the mass of the second soft magnetic powder may be expressed as M2. M1 / (M1+M2) may be between 0.70 and 0.95, and M2 / (M1+M2) may be between 0.05 and 0.30. When M1 / (M1+M2) and M2 / (M1+M2) are within the above ranges, the second soft magnetic particles, which are smaller than the first soft magnetic particles, are more likely to fill the gaps between multiple first soft magnetic particles, and the filling rate of the metal powder in the compound (specific gravity of the compound) tends to increase. As a result, the relative permeability and mechanical strength tend to increase.

[0033] The average particle size D50 and D90 of the metal powder may be calculated from the particle size distribution based on the volume, number, or mass of the metal particles constituting the metal powder. The average particle size D50 and D90 of the first soft magnetic powder may be calculated from the particle size distribution based on the volume, number, or mass of the first soft magnetic particles constituting the first soft magnetic powder. The average particle size D50 and D90 of the second soft magnetic powder may be calculated from the particle size distribution based on the volume, number, or mass of the second soft magnetic particles constituting the second soft magnetic powder. Each particle size distribution may be measured by a laser diffraction particle size distribution analyzer. Each particle size distribution may also be calculated based on the measurement of the volume or mass of each particle classified by one or more sieves having a predetermined mesh size. The shapes of the metal powder (metal particles), the first soft magnetic particles, and the second soft magnetic particles are not particularly limited. For example, the shapes of the metal powder (metal particles), the first soft magnetic particles, and the second soft magnetic particles may be spherical, nearly spherical, flattened, or needle-shaped.

[0034] As long as the metal powder is a soft magnetic material, the composition of the metal powder (each of the multiple metal particles) is not particularly limited. For example, the metal powder may contain iron. In addition to iron, the metal powder may further contain at least one metal element selected from the group consisting of base metal elements, noble metal elements, transition metal elements, and rare earth elements. For example, the metal element other than iron contained in the metal powder may be at least one element selected from the group consisting of cobalt (Co), nickel (Ni), copper (Cu), titanium (Ti), manganese (Mn), zinc (Zn), aluminum (Al), tin (Sn), arsenic (As), antimony (Sb), chromium (Cr), beryllium (Be), barium (Ba), strontium (Sr), lead (Pb), bismuth (Bi), silver (Ag), niobium (Nb), hafnium (Hf), zirconium (Zr), tantalum (Ta), molybdenum (Mo), tungsten (W), and vanadium (V). The metal powder may contain nonmetallic elements in addition to metallic elements. For example, the nonmetallic element contained in the metal powder may be at least one element selected from the group consisting of boron (B), carbon (C), nitrogen (N), oxygen (O), silicon (Si), phosphorus (P), and sulfur (S). For example, when the metal powder (e.g., the first soft magnetic powder) contains Cr, oxidation of the metal powder is easily suppressed, the metal powder is less prone to rusting, and the decrease in relative permeability is easily suppressed.

[0035] The metal powder may contain at least one metal from among pure iron and iron-containing alloys (iron-based alloys). The metal powder may consist only of pure iron. The metal powder may consist only of iron-based alloys. The metal powder may consist only of pure iron and iron-based alloys. For example, the pure iron may be carbonyl iron powder. Carbonyl iron powder is Fe(CO) ５ This is a perfectly spherical pure iron powder obtained by the reduction (thermal decomposition) of (iron pentacarbonyl). For example, the iron-based alloy contained in the metal powder may be at least one alloy selected from the group consisting of Fe-Cr-Si alloys, Fe-Cr alloys, Fe-Si alloys, Fe-Si-Al alloys, Fe-Ni alloys, Fe-Cu-Ni alloys, Fe-Co alloys, and Fe-Ni-Cr alloys. The iron or iron-based alloy contained in the metal powder may be crystalline or amorphous. The metal powder may contain metal nanocrystals.

[0036] Some or all of the plurality of metal particles constituting the metal powder may be covered with an insulating film. Some or all of the surface of each metal particle may be covered with an insulating film. By covering the metal powder with an insulating film, the electrical insulation of the compound is improved. When the insulating film contains glass, the surface of the insulating film tends to be smooth, and the friction between the plurality of metal particles is likely to be suppressed. As a result, the aggregation (blocking) of the compound is likely to be suppressed, and the fluidity of the compound is likely to be improved. Part or all of the surface of the insulating film may be covered with a resin composition.

[0037] For example, the insulating film may contain at least one component selected from the group consisting of glass, phosphoric acid (phosphate), silica (SiO ２ ), iron oxide (Fe ２ O ３ ), and chromium oxide (Cr ２ O ３ ). For example, 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). The composition of the insulating film may be measured by at least one of X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDX). The insulating film may be formed by a wet method using a solution of alkoxysilane or the like, or a dry method such as mechanofusion. For example, the thickness of the insulating film may be 10 nm or more and 200 nm or less. The thickness of the insulating film may be measured at the cross section of the metal particles by a transmission electron microscope (TEM) and EDX.

[0038] In addition to the metal powder, the compound may further contain a filler made of a non-metal. For example, the compound may contain a filler made of silica (SiO ２ ) as a filler made of a non-metal (particulate filler). <00​(Specific Examples of Resin Compositions) The resin composition may be the remaining part (non-volatile component) of the compound excluding the metal powder. As described above, the resin composition contains at least an epoxy resin and a curing agent. The curing agent contains at least a triphenylmethane type phenolic resin and a phenol novolak resin. The epoxy resin may be the main component of the resin composition. That is, the content (unit: mass %) of the epoxy resin among all the components constituting the resin composition may be the largest. In addition to the epoxy resin and the curing agent, the resin composition may further contain at least one component selected from the group consisting of a curing accelerator (curing catalyst), a coupling agent, a wax (release agent), a dispersant, and a flame retardant. Specific examples of each component may be as follows.

[0040] The resin composition may further contain a thermosetting resin different from the epoxy resin. For example, the thermosetting resin different from the epoxy resin may be at least one resin selected from the group consisting of a phenolic resin, a bismaleimide resin, a polyimide resin, and a polyamideimide resin. In addition to the thermosetting resin such as the epoxy resin, the resin composition may further contain another resin (for example, a thermoplastic resin). For example, the resin composition may further contain at least one other resin selected from the group consisting of a polyphenylene sulfide resin, an acrylic resin, a methacrylic resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, and a silicone resin.

[0041] <Epoxy Resins and Curing Agents> Epoxy resins include trisphenolmethane type epoxy resins, biphenylaralkyl type epoxy resins, 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, copolymer epoxy resins of naphthols and phenols, epoxidized aralkyl type phenol resins, bisphenol type epoxy resins, glycidyl ether type epoxy resins of alcohols, glycidyl ether type epoxy resins of paraxylylene-modified phenol resins and / or metaxylylene-modified phenol resins, and terpene-modified phenol The resin may be at least one resin selected from the group consisting of glycidyl ether type epoxy resins, cyclopentadiene type epoxy resins, glycidyl ether type epoxy resins of polycyclic aromatic ring-modified phenol resins, glycidyl ether type epoxy resins of naphthalene ring-containing phenol resins, glycidyl ester type epoxy resins, glycidyl type or methylglycidyl type epoxy resins, alicyclic epoxy resins, halogenated phenol novolac type epoxy resins, orthocresol novolac type epoxy resins, hydroquinone type epoxy resins, trimethylolpropane type epoxy resins, and linear aliphatic epoxy resins obtained by oxidizing olefin bonds with peracids such as peracetic acid.

[0042] At least some of the epoxy resins may be naphthalene-type epoxy resins having a naphthalene structure. Naphthalene-type epoxy resins are solid at room temperature. When the compound contains a naphthalene-type epoxy resin, the product manufactured from the compound (cured compound) tends to have high mechanical strength at both room temperature and high temperatures. The naphthalene-type epoxy resin may be at least one resin selected from the group consisting of naphthalene diepoxy compounds, naphthylene ether-type epoxy resins, naphthalene novolac-type epoxy resins, methylene-bonded dimers of naphthalene diepoxy compounds, and methylene-bonded compounds of naphthalene monoepoxy compounds and naphthalene diepoxy compounds. The epoxy resin may also include a bifunctional epoxy resin. For example, the bifunctional epoxy resin may be at least one resin from among α-naphthol-type epoxy resins and β-naphthol-type epoxy resins.

[0043] The epoxy resin may contain at least one of the trifunctional epoxy resins and tetrafunctional epoxy resins. The naphthalene-type epoxy resin described above may be at least one of the trifunctional epoxy resins and tetrafunctional epoxy resins. A trifunctional epoxy resin is an epoxy resin composed of structural units having three epoxy groups. A tetrafunctional epoxy resin is an epoxy resin composed of structural units having four epoxy groups. When the epoxy resin contains at least one of the trifunctional epoxy resins and tetrafunctional epoxy resins, the epoxy resins are crosslinked three-dimensionally during the thermal curing process of the compound, forming a strong crosslinked network. As a result, the movement of the epoxy resin in the cured compound is easily suppressed at high temperatures. In other words, the glass transition temperatures of the trifunctional epoxy resins and tetrafunctional epoxy resins are higher than those of the difunctional epoxy resin. Therefore, when the epoxy resin contains at least one of the trifunctional epoxy resins and tetrafunctional epoxy resins, the cured compound tends to have high mechanical strength at high temperatures.

[0044] For example, epoxy resins may include trisphenolmethane type epoxy resins (triphenylmethane type epoxy resins). Among the various conventional epoxy resins, trisphenolmethane type epoxy resins have a relatively low viscosity. Therefore, trisphenolmethane type epoxy resins tend to reduce the viscosity of compounds, and compounds containing trisphenolmethane type epoxy resins are easily fluid. The number of epoxy groups in one structural unit (or repeating unit) constituting a trisphenolmethane type epoxy resin is at least three. In other words, trisphenolmethane type epoxy resins are polyfunctional epoxy resins (for example, trifunctional epoxy resins). To put it another way, among the various epoxy resins, the epoxy equivalent (unit: g / mol) of trisphenolmethane type epoxy resins is relatively small. Therefore, trisphenolmethane-type epoxy resins tend to increase the density of the crosslinked structure formed in the compound and raise the glass transition temperature Tg of the compound when a molded article containing an uncured or semi-cured compound is heated at a high temperature (for example, a temperature of 150°C or higher). Consequently, trisphenolmethane-type epoxy resins tend to increase the high-temperature mechanical strength of a molded article containing an uncured or semi-cured compound. Similar to trisphenolmethane-type epoxy resins, epoxy resins may include trifunctional epoxy resins that are derivatives of 1-[α-methyl-α-(4-hydroxyphenyl)ethyl]-4-[α,α-bis(4-hydroxyphenyl)ethyl]benzene for the same reason that they tend to increase the high-temperature mechanical strength of a molded article containing an uncured or semi-cured compound.

[0045] For the reasons that the fluidity of the compound is easily improved and the mechanical strength of the molded article containing the uncured or semi-cured compound is easily increased at high temperatures, the total epoxy resin content ([epoxy]) in the compound may be 1.60% by mass or more and 1.92% by mass or less.

[0046] The compound may contain one of the epoxy resins listed above. The compound may contain multiple types of epoxy resins listed above.

[0047] Curing agents are classified into two types: those that cure epoxy resins in a low temperature to room temperature range, and heat-curing curing agents that cure epoxy resins upon heating. For example, curing agents that cure epoxy resins in a low temperature to room temperature range include aliphatic polyamines, polyaminoamides, and polymer captans. For example, heat-curing curing agents include aromatic polyamines, acid anhydrides, phenolic resins, phenol novolac resins, and dicyandiamide (DICY).

[0048] As described above, the curing agent includes a triphenylmethane-type phenolic resin and a phenol novolac resin. The curing agent may consist only of a triphenylmethane-type phenolic resin and a phenol novolac resin. In addition to the triphenylmethane-type phenolic resin and the phenol novolac resin, the curing agent may further include one or more other curing agents.

[0049] For example, the structural unit or repeating unit of a triphenylmethane-type phenolic resin may be represented by the following chemical formula 1. For example, a triphenylmethane-type phenolic resin may be represented by the following chemical formula 2. In chemical formula 2, n may be any integer greater than or equal to zero. However, the triphenylmethane-type phenolic resin is not limited to the compound represented by the following chemical formula 2. The resin composition may contain two or more triphenylmethane-type phenolic resins that differ in molecular structure, molecular weight, or hydroxyl group.

[0050] For example, a phenol novolac resin may be a resin obtained by condensing or co-condensing phenols and / or naphthols with aldehydes under an acidic catalyst. The phenols constituting the phenol novolac resin may be at least one selected from the group consisting of phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol. The naphthols constituting the phenol novolac resin may be at least one selected from the group consisting of α-naphthol, β-naphthol, and dihydroxynaphthalene. The aldehydes constituting the phenol novolac resin may be at least one selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde. The resin composition may contain two or more phenol novolac resins that differ in molecular structure, molecular weight, or hydroxyl group.

[0051] For the reasons that the fluidity of the compound is easily improved and the mechanical strength of the molded article containing the uncured or semi-cured compound is easily increased at high temperatures, the mass ratio (R(tri-nov)) of triphenylmethane-type phenolic resin and phenol novolac resin in all the curing agents contained in the compound may be 70% by mass or more and 100% by mass or less.

[0052] For example, phenol resins other than triphenylmethane-type phenol resins and phenol novolac resins may be at least one resin selected from the group consisting of aralkyl-type phenol resins, dicyclopentadiene-type phenol resins, salicylaldehyde-type phenol resins, copolymer phenol resins of benzaldehyde-type phenol and aralkyl-type phenol, paraxylylene and / or metaxylylene-modified phenol resins, melamine-modified phenol resins, terpene-modified phenol resins, dicyclopentadiene-type naphthol resins, cyclopentadiene-modified phenol resins, polycyclic aromatic ring-modified phenol resins, and biphenyl-type phenol resins. The phenol resin may also be a copolymer composed of two or more of the above-mentioned phenol resins.

[0053] For the reasons that the fluidity of the compound is easily improved and the mechanical strength of the molded article containing the uncured or semi-cured compound at high temperatures is easily increased, the mass ratio of all curing agents to 100 parts by mass of epoxy resin (<cure>) may be 59 parts by mass or more and 70 parts by mass or less.

[0054] For example, the ratio of the hydroxyl group equivalent of the curing agent to the epoxy equivalent of the epoxy resin may be between 0.5 and 1.5. In other words, the ratio of the active group (phenolic OH group) in the curing agent that reacts with the epoxy groups in the epoxy resin may be between 0.5 and 1.5 equivalents per equivalent of epoxy groups in the epoxy resin.

[0055] <Curing Accelerator> The curing accelerator (curing catalyst) may be any composition that reacts with the epoxy resin to accelerate its curing, and is not limited to any other composition. For example, the curing accelerator may be a urea compound. The curing accelerator may also be an alkyl-substituted imidazole or an imidazole such as benzimidazole. The curing accelerator may also be a phosphorus-based curing accelerator. The compound may contain one type of curing accelerator. The compound may contain multiple types of curing accelerators.

[0056] For the reason that the mechanical strength of the cured compound is easily increased, the curing accelerator may contain one or more imidazoles. For example, one or more imidazoles may be one or more compounds selected from 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole (4-methyl-2-phenylimidazole), 2-phenyl-4-methyl-5-hydroxymethylimidazole, 1-aminopropyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, and 1-cyanoethyl-2-phenylimidazole.

[0057] The amount of curing accelerator added is not particularly limited. From the viewpoint of improving the curability and fluidity of the epoxy resin when it absorbs moisture, the amount of curing accelerator added may be 0.1 parts by mass or more and 30 parts by mass or less per 100 parts by mass of 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).

[0058] <Coupling Agent> The coupling agent may be a coupling agent that reacts with glycidyl groups present in a resin composition such as epoxy resin. The coupling agent improves the adhesion between the metal powder and the resin composition and improves the mechanical strength of the cured compound. The coupling agent that reacts with glycidyl groups may be a silane compound (silane coupling agent). For example, the silane coupling agent may be at least one coupling agent selected from the group consisting of epoxysilane, mercaptosilane, aminosilane, alkylsilane, ureidosilane, acid anhydride silane, methacrylicsilane, and vinylsilane. The compound may contain one of the above coupling agents. The compound may contain multiple types of the above coupling agents.

[0059] <Wax> The compound may contain wax. Wax may be rephrased as a lubricant or release agent. The inclusion of wax in the compound improves its fluidity and moldability, and improves its release properties. As a result, the accuracy of the shape and dimensions of the product manufactured from the compound (cured compound) is improved, and structural defects in the product are more easily suppressed. For example, the wax may be at least one compound from saturated fatty acids, saturated fatty acid salts, saturated fatty acid esters, and fatty acid amides. The wax may also be a synthetic wax. The compound may contain one of the above waxes. The compound may contain multiple types of the above waxes.

[0060] <Dispersant> The compound may contain a dispersant. For example, the dispersant may be at least one phosphate ester selected from the group consisting of phosphate monoesters, phosphate diesters, and phosphate triesters.

[0061] <Flame Retardants> The compound may contain flame retardants. For example, the flame retardant may be at least one compound selected from the group consisting of brominated flame retardants, phosphorus-based flame retardants, hydrated metal compound-based flame retardants, silicone-based flame retardants, nitrogen-containing compounds, hindered amine compounds, organometallic compounds, and aromatic engineering plastics. The compound may contain one of the above flame retardants, or more of the above flame retardants.

[0062] (Method for manufacturing the compound) The method for manufacturing the compound includes the step of preparing a mixed powder containing a metal powder and a resin composition.

[0063] For example, a mixed powder may be obtained by kneading a metal powder and each component constituting a resin composition while heating. A lump of mixed powder (aggregated mixed powder) may be obtained by heating and kneading the metal powder and the resin composition, and the mixed powder may be obtained by grinding the lump of mixed powder.

[0064] For example, the means for mixing the metal powder and the resin composition may be a kneader, rolls, or a stirrer. By heating and mixing the metal powder and the resin composition, the resin composition may coat part or all of the surface of each metal particle constituting the metal powder. By heating and mixing the metal powder and the resin composition, part or all of the resin composition may become a semi-cured product.

[0065] The metal powder and all the components constituting the resin composition may be kneaded together. A mixture of metal powder and a coupling agent may be prepared in advance, and this mixture may be kneaded with the other components of the resin composition. A mixture of each component of the resin composition, excluding the curing accelerator, and the metal powder may be prepared in advance, and this mixture may be kneaded with the curing accelerator. A mixture of each component of the resin composition, excluding the wax, and the metal powder may be prepared in advance, and this mixture may be kneaded with the wax.

[0066] The mixing time depends on the type of mixing means, the volume of the mixing means, and the amount of compound to be produced. The mixing time is not limited. For example, the mixing time may be between 1 minute and 20 minutes. For example, the temperature of the metal powder and resin composition during mixing (heating temperature) may be below the thermosetting temperature of the thermosetting resin. The heating temperature may be a temperature at which a semi-cured product of the thermosetting resin (B-stage resin composition) is formed and the formation of a cured product of the thermosetting resin (C-stage resin composition) is suppressed. The heating temperature may be lower than the activation temperature of the curing accelerator. For example, the heating temperature may be between 50°C and 150°C.

[0067] The method for preparing the mixed powder is not limited to the method described above. For example, a mixture may be obtained by kneading a metal powder, a resin composition, and an organic solvent while heating, and the mixed powder may be obtained by drying (and grinding) the mixture. When the organic solvent in which the resin composition is dissolved comes into contact with the surface of the metal particles, the metal particles are easily covered with the resin composition. For similar reasons, a mixture may be obtained by mixing the metal powder and the resin composition in an organic solvent, and the mixed powder may be obtained by drying (and grinding) the mixture. 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, and N-methyl-2-pyrrolidone (NMP).

[0068] The above mixed powder itself may be used as a compound. A compound with an adjusted particle size distribution may be obtained by grinding the mixed powder. A compound with an adjusted particle size distribution may be obtained by classifying the mixed powder using a sieve. The above mixed liquid itself (i.e., paste) may be used as a compound.

[0069] (Methods for manufacturing molded articles, cured products, magnetic cores, and coil components) A molded article is obtained by molding the compound described above. By heat treatment of the molded article (thermosetting of the resin composition in the molded article), multiple metal particles are firmly bonded to each other by the cured resin composition, and a cured compound (e.g., a magnetic core) is obtained. For example, the method for molding the compound may be transfer molding, extrusion molding, or compression molding. Transfer molding is a type of injection molding. Transfer molding may be rephrased as pressure molding. Transfer molding may include the steps of heating the compound in a heating chamber to make it fluid, and supplying (pressure-injecting) the fluidized compound from the heating chamber into the mold through a casting runner. Depending on the industrial product (e.g., a coil component) to be manufactured using the compound, the dimensions and shape of the mold used for molding the compound may be selected. The heat treatment temperature of the molded body may be any temperature at which the resin composition in the molded body is sufficiently cured, and may be above the activation temperature of the curing accelerator. For example, the heat treatment temperature may be between 100°C and 300°C. For example, the heat treatment time may be between a few minutes and 10 hours. To suppress the oxidation of the metal powder in the molded body, the heat treatment of the molded body may be carried out under an inert atmosphere. A paste which is a mixture of the compound and an organic solvent may be used to manufacture a molded body containing the compound, a cured product of the compound, a magnetic core containing the cured product of the compound, and a coil component containing the cured product of the compound.

[0070] (Analysis Method) The composition of the compound used in the manufacture of the molded article and the cured product may be retrospectively analyzed by analyzing the samples obtained by crushing the molded article and the cured product, respectively. The sample may be dissolved in an organic solvent, and the metal powder may be separated from the resin composition dissolved in the organic solvent. The separated metal powder and resin composition may be analyzed individually. Even when the unused compound itself is analyzed directly, the separated metal powder and resin composition may be analyzed individually using the method described above. For example, metal powders 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 constituting the resin composition 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.

[0071] This disclosure is not necessarily limited to the embodiments described above. Various modifications to this disclosure are possible and are included in this disclosure, without departing from the spirit of this disclosure.

[0072] For example, industrial products manufactured using the compound are not limited to inductors. Specific industrial products manufactured using the compound may include reactors, transformers, motor stators, motor yokes, power modules, thyristor valves, noise filters (EMI filters), choke coils, and solenoid cores.

[0073] The compound, the molded article containing the compound, or the cured product of the compound may be a encapsulant (for example, an encapsulant for electronic components). The compound can possess both the electrical insulation properties required for encapsulants for electronic or electrical equipment and the soft magnetic properties (electromagnetic shielding ability) required for electromagnetic shielding materials. For example, the compound, the molded article containing the compound, or the cured product of the compound may be an encapsulant (underfill, etc.) for semiconductor packages such as IC packages and LSI packages.

[0074] The present disclosure will be illustrated in detail by the following examples and comparative examples. The present disclosure is not limited to the following examples.

[0075] [Components included in the resin composition] The "Resin 1" described below was a trisphenolmethane type epoxy resin (grade; 1032H60) manufactured by Mitsubishi Chemical Corporation. The epoxy equivalent of "Resin 1" was 169 g / mol.

[0076] The "Resin 2" described below is TECHMORE VG-3101L manufactured by Printec Co., Ltd., and is a trifunctional epoxy resin that is a derivative of 1-[α-methyl-α-(4-hydroxyphenyl)ethyl]-4-[α,α-bis(4-hydroxyphenyl)ethyl]benzene. The epoxy equivalent of "Resin 2" was 212 g / mol.

[0077] The "Resin 3" described below was NC-3000 manufactured by Nippon Kayaku Co., Ltd., and was a biphenyl aralkyl type epoxy resin. The epoxy equivalent of "Resin 3" was 274 g / mol.

[0078] The "curing agent 1" described below was MEHC7841 manufactured by UBE Corporation (formerly Meiwa Kasei Co., Ltd.), and was a biphenyl aralkyl type phenolic resin. The hydroxyl group equivalent of "curing agent 1" was 167 g / mol.

[0079] The "curing agent 2" described below was HF-3M manufactured by UBE Corporation (formerly Meiwa Kasei Co., Ltd.), and was a phenol novolac resin. The hydroxyl group equivalent of "curing agent 2" was 106 g / mol.

[0080] The "curing agent 3" described below was HE910 manufactured by Air Water Performance Chemical Co., Ltd., and was a triphenylmethane-type phenolic resin. The hydroxyl group equivalent of "curing agent 3" was 104 g / mol.

[0081] The "curing agent 4" described below was MEW-1800 manufactured by UBE Corporation (formerly Meiwa Kasei Co., Ltd.), and was a phenol novolac resin. The hydroxyl group equivalent of "curing agent 4" was 105 g / mol.

[0082] The "curing agent 5" described below was MEHC7851 manufactured by UBE Corporation (formerly Meiwa Kasei Co., Ltd.), and was a biphenyl aralkyl type phenolic resin. The hydroxyl group equivalent of "curing agent 5" was 199 g / mol.

[0083] The "curing accelerator 1" described below was 2P4MHZ-PW manufactured by Shikoku Chemicals Co., Ltd., and was 2-phenyl-4-methyl-5-hydroxymethylimidazole.

[0084] The "curing accelerator 2" described below was U-CAT3512T manufactured by Sunapro Co., Ltd., and was an aromatic dimethylurea.

[0085] The "coupling agent 1" described below was KBM-5803 manufactured by Shin-Etsu Chemical Co., Ltd., and was 8-methacryloxyoctyltrimethoxysilane.

[0086] The "coupling agent 2" described below was KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd., and was 3-glycidoxypropyltrimethoxysilane.

[0087] The "release agent 1" described below was zinc stearate.

[0088] The "release agent 2" described below was Licowax OP manufactured by Clariant Chemicals Co., Ltd., which was a montanic acid ester partially saponified with calcium hydroxide.

[0089] The "dispersant" described below was a phosphate ester.

[0090] [Components contained in the metal powder] A mixture consisting of powder 1 and powder 2 was used as the metal powder.

[0091] Powder 1 was 9A4-K manufactured by Epson Atomics Corporation and was a metal (soft magnetic material) composed of Fe, Si, and B. Powder 1 was amorphous. The cutoff diameter of powder 1 was 53 μm. In other words, particles with a particle size (maximum particle width) larger than 53 μm were removed from powder 1 by sieving. The average particle size of powder 1 was 25 μm. The content of powder 1 in the metal powder was 82% by mass.

[0092] Powder 2 was YF-T6A manufactured by JIANGXI YUEAN ADVANCED MATERIALSCO., LTD., and was a carbonyl iron powder (soft magnetic material). The average particle size of powder 2 was within the range of 1.5 to 1.8 μm. The content of powder 2 in the metal powder was 18% by mass.

[0093] (Example 1) The resin composition of Example 1 was a mixture consisting of resins 1 and 2, curing agents 1 to 4, curing accelerator 1, coupling agents 1 and 2, release agents 1 and 2, and a dispersant. The mass ratios (in parts by mass) of resins 1 and 2, curing agents 1 to 4, curing accelerator 1, coupling agents 1 and 2, release agents 1 and 2, and dispersant in the resin composition were adjusted to the values ​​shown in Table 1 below.

[0094] By kneading all the raw materials, consisting of the components of the resin composition and the metal powder, while heating, a compound (powder) consisting only of the metal powder and the resin composition was obtained. The maximum temperature of all the raw materials during kneading was 130°C. The content of the metal powder in the compound (unit: mass%) was adjusted to 96.5% by mass. In other words, the content of the resin composition in the compound was adjusted to 3.5% by mass.

[0095] <Measurement of Disc Flow> 5g of compound was placed on the flat surface of the lower mold. The flat upper mold was pressed against the compound, sandwiching it between the upper and lower molds. By compressing the compound between the upper and lower molds with a load of 4kg for 300 seconds, a roughly disc-shaped molded body made of the compound was formed. The temperature of the compound during compression was maintained at 150°C. The maximum and minimum diameters of the disc-shaped molded body were measured. The average of the major and minor axes corresponds to the disc flow. The disc flow (unit: mm) for Example 1 is shown in Table 2 below. The more easily the compound flows, the larger the disc flow. A disc flow of 50 mm or more is desirable.

[0096] <Measurement of Stroke Length> The fluidity of the compound in Example 1 was evaluated using the following method with a flow tester. A CFT-100 manufactured by Shimadzu Corporation was used as the flow tester. The flow tester had a cylinder, a heater surrounding the side of the cylinder, and a plunger fitted into the cylinder. A tablet made of uncured compound was produced by molding 7 g of compound. The tablet was placed inside the cylinder. Next, the plunger was inserted into the cylinder from the opening. A circular discharge hole (orifice) was formed at the end of the cylinder opposite the opening. The inner diameter of the discharge hole was 1 mm. The tablet inside the cylinder was preheated to 150°C for 20 seconds using the heater. Following preheating, the plunger was pushed into the cylinder, and the tablet inside the cylinder was pressurized by the plunger. The load exerted by the plunger on the tablet was 10 kg. The point at which the compound began to flow out from the discharge hole is represented as t0. The point at which the outflow of compound from the discharge hole stops is denoted as t1. The flow time T is defined as t1 - t0. The stroke length is defined as the distance the plunger travels during the flow time T.

[0097] The stroke length (in mm) measured by the method described above is shown in Table 2 below. The more fluid the compound, the longer the stroke length. A stroke length of 9.0 mm or more is desirable.

[0098] <Measurement of Bending Strength> A test specimen (molded body) made of uncured compound was obtained by transfer molding of the compound at 150°C. The test specimen was a rectangular parallelepiped (rod). The pressure applied to the compound during transfer molding was 12.4 MPa. The dimensions of the test specimen were length L: 80 mm × width W: 10 mm × thickness t: 3.0 mm. A three-point support bending test was performed using the test specimen with an autograph equipped with a constant temperature chamber. The autograph used was an AGS-500A manufactured by Shimadzu Corporation. The temperature of the constant temperature chamber in which the test specimen was placed during the test was 150°C. In the bending test, one side of the test specimen (the side with dimensions L × W) was supported by two support points. A load was applied to the part of the other side of the test specimen located midway between the two support points. The deflection (elongation) of the test specimen at each load was continuously measured as the load increased. The load at which the specimen broke, and the deflection of the specimen immediately before breakage were measured. The measurement conditions for the bending test were as follows: Distance Lv between the two support points: 64.0 ± 0.5 mm; Head speed: 2.0 ± 0.2 mm / min; Chart speed: 100 mm / min; Chart full scale: 490 N (50 kgf)

[0099] The bending strength σ (unit: MPa) was calculated based on the following formula A: σ = (3 × P × Lv) / (2 × W × t) ２ ) (A) In formula A, "P" is the load (unit: N) at which the test specimen breaks. In formula A, "Lv" is the distance (unit: mm) between the two support points that support the test specimen. In formula A, "W" is the width (unit: mm) of the test specimen. In formula A, "t" is the thickness (unit: mm) of the test specimen. The bending strength of Example 1 is shown in Table 2 below. A bending strength of 40 MPa or higher is desirable.

[0100] <Measurement of Relative Permeability> A toroidal core (powder magnetic core) was obtained from the cured compound by transfer molding of the compound at 150°C and post-curing (heating at 180°C for 2 hours) following the transfer molding. The pressure applied to the compound during transfer molding was 6.9 MPa. The dimensions of the toroidal core were 20 mm outer diameter x 12 mm inner diameter x 2 mm thickness.

[0101] The relative permeability of the toroidal core was measured. An impedance analyzer (product name: E4990A) manufactured by Keysight Technologies, Inc. was used for the measurement. The frequency during the measurement was 1 MHz. The relative permeability (unit: none) is shown in Table 2 below. A relative permeability of 30 or higher is desirable.

[0102] <Measurement of Glass Transition Temperature Tg> Thermomechanical analysis (TMA) was performed on the compound. In the TMA, a molded body was formed by heating and pressurizing the uncured compound at 150°C and 12.4 MPa for 300 seconds. A test specimen (cured compound) was obtained by curing the molded body at 180°C for 2 hours. In the TMA, the test specimen was heated from room temperature (25°C) to 250°C. The load applied to the test specimen in the TMA was 10 g. The heating rate was 5°C / min. The glass transition temperature Tg (unit: °C) of the cured compound was measured by the above TMA. The Tg values ​​are shown in Table 2 below. A Tg value higher than 150°C is desirable.

[0103] (Examples 2-11, Comparative Examples 1 and 2) The mass ratios (in parts by mass) of resins 1-3, curing agents 1-5, curing accelerators 1 and 2, coupling agents 1 and 2, release agents 1 and 2, and dispersants in the resin compositions of Examples 2-11 and Comparative Examples 1 and 2 were adjusted to the values ​​shown in Table 1 below. The metal powder content ([metal]) in the compounds of Examples 2-11 and Comparative Examples 1 and 2 was adjusted to the values ​​shown in Table 2 below.

[0104] Compounds for Examples 2-11 and Comparative Examples 1 and 2 were prepared in the same manner as in Example 1, except for the matters described above. The disc flow, stroke length, bending strength, relative permeability, and glass transition temperature for Examples 2-11 and Comparative Examples 1 and 2 were measured in the same manner as in Example 1. The disc flow, stroke length, bending strength, relative permeability, and glass transition temperature for Examples 2-11 and Comparative Examples 1 and 2 are shown in Table 2 below.

[0105]

[0106] In Table 2 below, [metal] refers to the content of metal powder in the compound (unit: mass%). In Table 2 below, [resin] refers to the content of resin composition in the compound (unit: mass%). In Table 2 below, <tri-nov> refers to the mass ratio of triphenylmethane-type phenolic resin and phenol novolac resin to 100 parts by mass of epoxy resin (unit: parts by mass). In Table 2 below, R (tri-nov) refers to the mass ratio of triphenylmethane-type phenolic resin and phenol novolac resin in all curing agents contained in the compound (unit: mass%). In Table 2 below, <cure> refers to the mass ratio of all curing agents to 100 parts by mass of epoxy resin (unit: parts by mass). In Table 2 below, [epoxy] refers to the content of all epoxy resins in the compound (unit: mass%).

[0107]

[0108] For example, a compound relating to one aspect of this disclosure may be used as a raw material for coil components such as inductors.

[0109] 1... Coil component (inductor), 2... Hardened compound, 2dc... Magnetic core (e.g., compacted magnetic core), 3... Terminal electrode, 5... Coil, 5a, 5b... Coil lead-out sections.

Claims

1. A compound comprising a metal powder and a resin composition, wherein the metal powder is a soft magnetic material, the resin composition comprises an epoxy resin and a curing agent, the curing agent comprises a triphenylmethane-type phenolic resin and a phenol novolac resin, the content of the metal powder in the compound is 96.5% by mass or more and 98.0% by mass or less, the content of the resin composition in the compound is 2.0% by mass or more and 3.5% by mass or less, and the mass ratio of the triphenylmethane-type phenolic resin and the phenol novolac resin to 100 parts by mass of the epoxy resin is 47.0 parts by mass or more and 63.0 parts by mass or less.

2. The compound according to claim 1, wherein the epoxy resin comprises a trisphenolmethane type epoxy resin.

3. The compound according to claim 1, which is a raw material for the magnetic core.

4. A molded article comprising the compound according to any one of claims 1 to 3.

5. A cured compound according to any one of claims 1 to 3.

6. A magnetic core comprising the cured product described in claim 5.

7. A coil component comprising a magnetic core and a coil as described in claim 6, wherein the magnetic core is disposed inside the coil.

8. A coil component comprising the cured product described in claim 5, a coil, wherein the coil is sealed within the cured product.

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