Compounds, molded articles, and cured products

Abstract

A compound which comprises a metal powder and a resin composition comprising an epoxy resin, a hardener, and a dispersant, wherein the content of the metal powder is 90-98 mass% and the dispersant comprises a phosphoric acid ester.

Description

[Technical Field]

[0001] The present invention relates to compounds, molded articles, and cured products. [Background technology]

[0002] Compounds containing metal powder and resin compositions are used as raw materials for a variety of industrial products, depending on the physical properties of the metal powder. For example, compounds are used as raw materials for inductors, encapsulants, electromagnetic shields (EMI shields), or bonded magnets (see Patent Document 1 below). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-13803 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] When manufacturing industrial products from compounds, the compound is supplied and filled into molds through channels, and components such as coils are embedded in the compound within the molds. These processes require the compound to be fluid. However, as the metal powder content in the compound increases, the fluidity of the compound decreases significantly, and it becomes difficult to fill it into molds. With the miniaturization of electronic devices in recent years, the dimensions of the components mounted on electronic devices have become smaller. Therefore, when using compounds to manufacture components, it is necessary for the compound to flow in narrow channels and for the compound to uniformly fill the fine molds after passing through these narrow channels.

[0005] The present invention aims to provide a compound with excellent fluidity. The present invention also aims to provide a molded article containing the compound and a cured product of the compound. [Means for solving the problem]

[0006] A compound according to one aspect of the present invention comprises a metal powder and a resin composition containing an epoxy resin, a curing agent and a dispersant, wherein the metal powder content is 90% by mass or more and 98% by mass or less, and the dispersant contains a phosphate ester.

[0007] In one embodiment, the phosphate ester may have a group represented by -OR (where R represents an organic group having 4 or more carbon atoms).

[0008] In one embodiment, the organic group may be an alkyl group having 4 or more carbon atoms, or a group in which an ether bond is inserted into at least a portion of the carbon-carbon bonds in an alkyl group having 4 or more carbon atoms.

[0009] In one embodiment, alkyl groups and groups in which an ether bond is inserted into at least a portion of the carbon-carbon bond in the alkyl group may have substituents.

[0010] In one embodiment, the dispersant content may be 1 part by mass or less per 100 parts by mass of metal powder.

[0011] A molded article relating to one aspect of the present invention includes the above-mentioned compound.

[0012] A cured product relating to one aspect of the present invention is a cured product of the above compound. [Effects of the Invention]

[0013] The present invention provides a compound with excellent fluidity. Furthermore, the present invention provides a molded article and a cured product containing the compound. The compound of the present invention has low viscosity and excellent fluidity. Therefore, the compound can be filled into a mold with good filling properties. [Modes for carrying out the invention]

[0014] Preferred embodiments of the present invention will be described below. However, the present invention is not limited in any way to the embodiments described below.

[0015] [Compound] The compound according to this embodiment comprises a metal powder and a resin composition. The metal powder may contain at least one selected from the group consisting of, for example, elemental metals, alloys, amorphous powders, and metal compounds. The resin composition contains at least an epoxy resin, a curing agent, and a dispersant. The dispersant includes a phosphate ester. In the compound, the metal powder, epoxy resin, curing agent, and dispersant are mixed. The resin composition may further contain other components such as a curing accelerator, a mold release agent, and additives. The resin composition may be a component that can include the epoxy resin, curing agent, dispersant, curing accelerator, mold release agent, and additives, and may be the remaining components (non-volatile components) excluding the organic solvent and the metal powder. Additives are the remaining components of the resin composition excluding the epoxy resin, curing agent, dispersant, curing accelerator, and mold release agent. Additives are, for example, coupling agents, siloxane compounds, flame retardants, etc. The compound may be a powder (compound powder).

[0016] The compound may comprise metal powder and a resin composition adhering to the surface of individual metal particles constituting the metal powder. The resin composition may cover the entire surface of the particles or only a portion of the surface of the particles. The compound may comprise an uncured resin composition and metal powder. The compound may comprise a semi-cured resin composition (e.g., a B-stage resin composition) and metal powder. The compound may comprise both an uncured resin composition and a semi-cured resin composition. The compound may consist of metal powder and a resin composition.

[0017] The content of the metal powder in the compound is 90% by mass or more and 98% by mass or less. The content of the metal powder in the compound may preferably be 92% by mass or more and 98% by mass or less, 94% by mass or more and 97.5% by mass or less, or 96% by mass or more and 97.5% by mass or less. If the content of the metal powder in the compound without a dispersant is 90% by mass or more, the fluidity of the compound will be significantly reduced. On the other hand, the compound according to this embodiment contains a phosphate ester as a dispersant. As a result, although the content of the metal powder in the compound is 90% by mass or more, the compound according to this embodiment is superior in fluidity to the conventional compound.

[0018] The average particle diameter of the metal powder is not particularly limited, and may be, for example, 1 μm or more and 300 μm or less. The average particle diameter may be measured, for example, by a particle size distribution meter. The shape of each metal particle constituting the metal powder is not limited, and may be, for example, spherical, flat, prismatic or needle-shaped. The compound may include a plurality of types of metal powders having different average particle diameters.

[0019] Depending on the composition or combination of the metal powders contained in the compound, various properties such as the electromagnetic properties of the molded body and cured product formed from the compound can be freely controlled, so the molded body and cured product can be used for various industrial products or their raw materials. Industrial products manufactured using the compound may be, for example, automobiles, medical devices, electronic devices, electrical devices, information and communication devices, household appliances, audio devices, and general industrial devices. For example, when the compound contains a permanent magnet such as a Sm-Fe-N-based alloy or a Nd-Fe-B-based alloy as the metal powder, the compound may be used as a raw material for bonded magnets. When the compound contains a soft magnetic powder such as an Fe-Si-Cr-based alloy or ferrite as the metal powder, the compound may be used as a raw material for an inductor (for example, an EMI filter) or a transformer (for example, a magnetic core). When the compound contains iron and copper as the metal powder, a molded body (for example, a sheet) formed from the compound may be used as an electromagnetic wave shield.

[0020] (Resin composition) The resin composition has a function as a binder for metal particles constituting the metal powder, and imparts mechanical strength to a molded body and a cured product formed from the compound. For example, when the compound is molded under high pressure using a mold, the resin composition contained in the compound is filled between the metal particles and binds the particles to each other. By curing the resin composition, a cured product of the resin composition binds the metal particles more firmly together, and a molded body and a cured product having excellent mechanical strength are obtained.

[0021] The resin composition according to this embodiment contains an epoxy resin as a thermosetting resin, whereby the fluidity of the compound can be improved. The epoxy resin may be, for example, a resin having two or more epoxy groups in one molecule. The type of the epoxy resin is not particularly limited and can be selected according to the desired properties of the composition and the like.

[0022] Epoxy resins include, for example, 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, epoxy resins containing a bisphenol skeleton, glycidyl ether-type epoxy resins of alcohols, glycidyl ether-type epoxy resins of paraxylylene and / or metaxylylene-modified phenol resins, and glycidyl ether-type epoxy resins of terpene-modified phenol resins. It may contain at least one selected from the group consisting of 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.

[0023] In terms of fluidity, the epoxy resin may contain at least one selected from the group consisting of biphenyl-type epoxy resins, orthocresol novolac-type epoxy resins, phenol novolac-type epoxy resins, bisphenol-type epoxy resins, epoxy resins having a bisphenol skeleton, salicylaldehyde novolac-type epoxy resins, and naphthol novolac-type epoxy resins.

[0024] From the standpoint of mechanical strength, the epoxy resin may contain at least one selected from the group consisting of biphenylene aralkyl type epoxy resins and orthocresol novolac type epoxy resins.

[0025] The epoxy resin may be a crystalline epoxy resin. Despite having a relatively low molecular weight, crystalline epoxy resins have a relatively high melting point and excellent fluidity. A crystalline epoxy resin (highly crystalline epoxy resin) may include, for example, at least one selected from the group consisting of hydroquinone-type epoxy resins, bisphenol-type epoxy resins, thioether-type epoxy resins, and biphenyl-type epoxy resins. Examples of commercially available crystalline epoxy resins include Epiclon 860, Epiclon 1050, Epiclon 1055, Epiclon 2050, Epiclon 3050, Epiclon 4050, Epiclon 7050, Epiclon HM-091, Epiclon HM-101, Epiclon N-730A, Epiclon N-740, Epiclon N-770, Epiclon N-775, Epiclon Epiclon N-865, Epiclon HP-4032D, Epiclon HP-7200L, Epiclon HP-7200, Epiclon HP-7200H, Epiclon HP-7200HH, Epiclon HP-7200HHH, Epiclon HP-4700, Epiclon HP-4710, Epiclon HP-4770, Epiclon HP-5000, Epiclon HP-6000, N500P -2, and N500P-10 (all product names manufactured by DIC Corporation), NC-3000, NC-3000-L, NC-3000-H, NC-3100, CER-3000-L, NC-2 000-L, XD-1000, NC-7000-L, NC-7300-L, EPPN-501H, EPPN-501HY, EPPN-502H, EOCN-1020, EOCN-10 Examples include 2S, EOCN-103S, EOCN-104S, CER-1020, EPPN-201, BREN-S, BREN-10S (all product names manufactured by Nippon Kayaku Co., Ltd.), YX-4000, YX-4000H, YL4121H, and YX-8800 (all product names manufactured by Mitsubishi Chemical Corporation), and VG3101L (all product names manufactured by Printec Co., Ltd.).

[0026] The resin composition may contain one of the epoxy resins listed above. The resin composition may contain multiple types of epoxy resins listed above. Among the epoxy resins listed above, the resin composition may contain epoxy resins containing a biphenyl skeleton, orthocresol novolac type epoxy resins, and polyfunctional epoxy resins containing two or more epoxy groups.

[0027] 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. Examples of curing agents that cure epoxy resins in a low temperature to room temperature range include aliphatic polyamines, polyaminoamides, and polymercaptans. Examples of heat-curing curing agents include aromatic polyamines, acid anhydrides, phenol novolac resins, and dicyandiamide (DICY). The type of curing agent is not particularly limited and can be selected according to the desired properties of the composition.

[0028] When a curing agent is used that cures epoxy resin in the low to room temperature range, the glass transition point of the cured epoxy resin is low, and the cured epoxy resin tends to be soft. As a result, the molded body formed from the compound also tends to be soft. On the other hand, from the viewpoint of improving the heat resistance of the molded body, the curing agent may preferably be a heat-curing type curing agent, more preferably a phenolic resin, and even more preferably a phenol novolac resin. In particular, by using a phenol novolac resin as the curing agent, it is easier to obtain a cured epoxy resin with a high glass transition point. As a result, the heat resistance and mechanical strength of the molded body tend to improve.

[0029] The phenol resin may include, for example, at least one selected from the group consisting of aralkyl phenol resin, dicyclopentadiene phenol resin, salicylaldehyde phenol resin, novolac phenol resin, copolymer phenol resin of benzaldehyde phenol and aralkyl phenol, paraxylylene and / or metaxylylene modified phenol resin, melamine modified phenol resin, terpene modified phenol resin, dicyclopentadiene naphthol resin, cyclopentadiene modified phenol resin, polycyclic aromatic ring modified phenol resin, biphenyl phenol resin, biphenylene aralkyl phenol resin, and triphenylmethane phenol resin. The phenol resin may also be a copolymer composed of two or more of the above. As commercially available phenol resins, for example, Tamanol 758 manufactured by Arakawa Chemical Industries, Ltd., HP-850N manufactured by Hitachi Chemical Co., Ltd., MEHC-7500-3S, MEHC-7851SS manufactured by Meiwa Chemical Co., Ltd. may be used.

[0030] The 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 include, for example, 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 include, for example, at least one selected from the group consisting of α-naphthol, β-naphthol, and dihydroxynaphthalene. The aldehydes constituting the phenol novolac resin may include, for example, at least one selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde.

[0031] The curing agent may be, for example, a compound having two phenolic hydroxyl groups in one molecule. The compound having two phenolic hydroxyl groups in one molecule may include, for example, at least one selected from the group consisting of resorcinol, catechol, bisphenol A, bisphenol F, and substituted or unsubstituted biphenols.

[0032] The resin composition may contain one of the above-mentioned phenolic resins. The resin composition may comprise multiple of the above-mentioned phenolic resins. The resin composition may contain one of the above-mentioned curing agents. The resin composition may comprise multiple of the above-mentioned curing agents.

[0033] The ratio of active groups (phenolic OH groups) in the curing agent that react with epoxy groups in the epoxy resin is preferably 0.5 to 1.5 equivalents, more preferably 0.6 to 1.4 equivalents, and even more preferably 0.7 to 1.2 equivalents per equivalent of epoxy groups in the epoxy resin. If the ratio of active groups in the curing agent is less than 0.5 equivalents, it is difficult to obtain a sufficient elastic modulus of the resulting cured product. On the other hand, if the ratio of active groups in the curing agent exceeds 1.5 equivalents, the mechanical strength of the molded article formed from the compound tends to decrease after curing. However, even if the ratio of active groups in the curing agent is outside the above range, the effects of the present invention can still be obtained.

[0034] The fluidity of the compound can be improved by including a dispersant containing a phosphate ester in the resin composition. This suppresses unfilled areas during molding and the generation of voids in the molded product. The reason why the fluidity of the compound is improved is not entirely clear, but the inventors surmise that the phosphate groups of the phosphate ester are selectively adsorbed onto the metal powder, thereby improving the dispersibility of the metal powder and thus improving the fluidity.

[0035] Phosphate esters are O=P(OH) 3-n (OR) nThe compound is represented by (n=1~3). The phosphate ester may be any of phosphate monoester, phosphate diester, or phosphate triester, but from the viewpoint of improving the fluidity of the compound, it may be a phosphate monoester or phosphate diester in which n in the above formula is 1 or 2.

[0036] The phosphate ester may preferably have a group represented by -OR (where R represents an organic group with 4 or more carbon atoms). Having 4 or more carbon atoms in the organic group included in the ester moiety makes it easier to improve the fluidity of the compound. From this viewpoint, the number of carbon atoms in R may be 5 or more, or 6 or more. Also, from the viewpoint of metal powder dispersibility, the number of carbon atoms in R may be 20 or less, or 15 or less.

[0037] The organic group may be an alkyl group having 4 or more carbon atoms, or a group in which an ether bond is inserted into at least some of the carbon-carbon bonds in an alkyl group having 4 or more carbon atoms. This makes it easier to improve the fluidity of the compound. The alkyl group may be linear or branched.

[0038] Alkyl groups, and groups in which an ether bond is inserted into at least a portion of the carbon-carbon bond within the alkyl group, may have substituents (reactive groups). This further improves the compatibility between the resin and the dispersant contained in the resin composition. Examples of substituents include amino groups, ureido groups, epoxy groups, thiol groups, (meth)acryloyl groups, and hydroxyl groups. Note that the "number of carbon atoms" in the organic group R mentioned above does not include the number of carbon atoms included in the substituents.

[0039] Examples of commercially available phosphate esters include JP-504, JP-506H, JP-508, and JP-513, manufactured by Johoku Chemical Industry Co., Ltd. Compound 1, represented by the following chemical formula 1, may be, for example, JP-504. Compound 2, represented by the following chemical formula 2, may be, for example, JP-506H. Compound 3, represented by the following chemical formula 3, may be, for example, JP-508. Compound 4 represented by the following Chemical Formula 4 may be, for example, the above JP-513. (C4H9O) n OP(OH) 3-n (1) n in the above Chemical Formula 1 may be 1 or 2. n in the above Chemical Formula 1 may be 1 or more and 3 or less. (C4H9OCH2CH2O) n OP(OH) 3-n (2) n in the above Chemical Formula 2 may be 1 or 2. n in the above Chemical Formula 2 may be 1 or more and 3 or less. (C4H9C2H5CHCH2O) n OP(OH) 3-n (3) n in the above Chemical Formula 3 may be 1 or 2. n in the above Chemical Formula 3 may be 1 or more and 3 or less. (isо-C 13 H 27 O) n OP(OH) 3-n (4) n in the above Chemical Formula 4 may be 1 or 2. n in the above Chemical Formula 4 may be 1 or more and 3 or less.

[0040] From the viewpoint of improving the fluidity of the compound, the blending amount of the dispersant may be 1 part by mass or less, 0.5 part by mass or less, 0.1 part by mass or less, or 0.05 part by mass or less with respect to 100 parts by mass of the metal powder. From the same viewpoint, the blending amount may be 0.01 part by mass or more.

[0041] The curing accelerator is not limited as long as it is, for example, a composition that reacts with an epoxy resin to accelerate the curing of the epoxy resin. The curing accelerator may be, for example, a phosphorus-based curing accelerator, an imidazole-based curing accelerator, or a urea-based curing accelerator. By the resin composition containing the curing accelerator, the moldability and releasability of the compound can be improved. Further, by the resin composition containing the curing accelerator, the mechanical strength of a molded body or cured product (for example, an electronic component) produced using the compound is improved, or the storage stability of the compound in a high-temperature and high-humidity environment is improved.

[0042] Examples of phosphorus-based curing accelerators include phosphine compounds and phosphonium salt compounds.

[0043] Commercial imidazole-based curing accelerators may include, for example, at least one selected from the group consisting of 2MZ-H, C11Z, C17Z, 1,2DMZ, 2E4MZ, 2PZ-PW, 2P4MZ, 1B2MZ, 1B2PZ, 2MZ-CN, C11Z-CN, 2E4MZ-CN, 2PZ-CN, C11Z-CNS, 2P4MHZ, TPZ, and SFZ (all trade names of Shikoku Chemicals, Inc.).

[0044] While the urea-based curing accelerator is not particularly limited as long as it has a urea group, it is preferable to use an alkylurea-based curing accelerator having an alkylurea group from the viewpoint of improving storage stability. Examples of alkylurea-based curing accelerators having an alkylurea group include aromatic alkylureas and aliphatic alkylureas. Examples of commercially available alkylurea-based curing accelerators include U-CAT3512T (trade name, manufactured by Sunapro Co., Ltd., aromatic dimethylurea) and U-CAT3513N (trade name, manufactured by Sunapro Co., Ltd., aliphatic dimethylurea). Among these, aromatic alkylureas are preferred because they have a moderately low cleavage temperature and can efficiently cure compounds.

[0045] The amount of curing accelerator added is not particularly limited, as long as it is sufficient to achieve a curing-accelerating effect. However, from the viewpoint of improving the curability and fluidity of the resin composition when it absorbs moisture, the amount of curing accelerator added may be preferably 0.1 parts by mass or more and 30 parts by mass or less, and more preferably 1 part by mass or more and 15 parts by mass or less, per 100 parts by mass of epoxy resin. The content of the curing accelerator is preferably 0.001 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the total mass of epoxy resin and phenolic resin. If the amount of curing accelerator added is less than 0.1 parts by mass, it is difficult to obtain a sufficient curing-accelerating effect. If the amount of curing accelerator added exceeds 30 parts by mass, the storage stability of the compound tends to decrease. However, even if the amount and content of the curing accelerator are outside the above ranges, the effects of the present invention can still be obtained.

[0046] The coupling agent improves the adhesion between the resin composition and the metal element-containing particles constituting the metal powder, thereby improving the flexibility and mechanical strength of the molded article formed from the compound. The coupling agent may be at least one selected from the group consisting of, for example, silane compounds (silane coupling agents), titanium compounds, aluminum compounds (aluminum chelates), and aluminum / zirconium compounds. The silane coupling agent may be at least one selected from the group consisting of, for example, epoxysilane, mercaptosilane, aminosilane, alkylsilane, ureidosilane, acid anhydride silane, vinylsilane, and (meth)acryloyloxysilane. The resin composition may contain one of the above coupling agents, or may contain multiple of the above coupling agents.

[0047] The resin composition may contain a compound having a siloxane bond (siloxane compound) because it is easier to reduce the molding shrinkage rate of the compound and to improve the heat resistance and voltage resistance of the molded article. A siloxane bond is a bond containing two silicon atoms (Si) and one oxygen atom (O), and may be represented as -Si-O-Si-. The compound having a siloxane bond may be a polysiloxane compound.

[0048] For environmental safety, recyclability, moldability, and low cost, the compound may contain a flame retardant. The flame retardant may be at least one selected from the group consisting of, for example, 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 resin composition may contain one of the above flame retardants, or may contain multiple of the above flame retardants.

[0049] When forming a molded body from a compound using a mold, the resin composition may contain a release agent. The release agent also functions as an agent to improve the fluidity of the compound during molding (e.g., transfer molding). Examples of release agents include fatty acids such as higher fatty acids, fatty acid esters, and fatty acid metal salts.

[0050] Release agents include, for example, fatty acids such as montanic acid, stearic acid, 12-oxystearic acid, and lauric acid, or their esters (e.g., alkyl esters); fatty acid salts such as zinc stearate, calcium stearate, barium stearate, aluminum stearate, magnesium stearate, calcium laurate, zinc linoleate, calcium ricinoleate, and zinc 2-ethylhexoate; stearamide, oleamide, erucamide, behenamide, palmitamide, lauamide, hydroxystearamide, methylenebisstearateamide, ethylenebisstearateamide, ethylenebislaurateamide, distearyl adipic acid amide, and ethylenebisoleamide. It may be at least one selected from the group consisting of: fatty acid amides such as dioleyl adipic acid amide, N-stearyl stearate amide, N-oleyl stearate amide, N-stearyl erucate amide, methylol stearate amide, and methylol behenate amide; alcohols such as ethylene glycol and stearyl alcohol; polyethers consisting of polyethylene glycol, polypropylene glycol, polytetramethylene glycol and modified products thereof; fluorine compounds such as fluorine-based oils, fluorine-based greases, and fluorine-containing resin powders; and waxes such as paraffin wax, polyethylene wax, amide wax, polypropylene wax, ester wax, carnauba wax, and microwax.

[0051] (metal powder) Metal powder (metal element-containing particles) may contain, for example, at least one selected from the group consisting of elemental metals, alloys, and metal compounds. Metal powder may consist of, for example, at least one selected from the group consisting of elemental metals, alloys, and metal compounds. Alloys may contain at least one selected from the group consisting of solid solutions, eutectics, and intermetallic compounds. Alloys may be, for example, stainless steel (Fe-Cr alloys, Fe-Ni-Cr alloys, etc.). Metal compounds may be oxides such as ferrite. Metal powder may contain one metal element or multiple metal elements. Metal elements contained in metal powder may be, for example, base metals, noble metals, transition metals, or rare earth elements. Compounds may contain one type of metal powder, or multiple types of metal powders with different compositions.

[0052] The metal powder is not limited to the above composition. The metal element contained in the metal powder may be at least one selected from the group consisting of, for example, iron (Fe), copper (Cu), titanium (Ti), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), tin (Sn), chromium (Cr), niobium (Nb), barium (Ba), strontium (Sr), lead (Pb), silver (Ag), praseodymium (Pr), neodymium (Nd), samarium (Sm), and dysprosium (Dy). The metal powder may further contain elements other than metal elements. For example, the metal powder may contain carbon (C), oxygen (O), beryllium (Be), phosphorus (P), sulfur (S), boron (B), or silicon (Si).

[0053] The metal powder may be magnetic powder. The metal powder may be a soft magnetic alloy or a ferromagnetic alloy. The metal powder may be a magnetic powder consisting of at least one selected from the group consisting of, for example, Fe-Si alloys, Fe-Si-Al alloys (Sendust), Fe-Ni alloys (Permalloy), Fe-Cu-Ni alloys (Permalloy), Fe-Co alloys (Permendur), Fe-Cr-Si alloys (electromagnetic stainless steel), Nd-Fe-B alloys (rare earth magnets), Sm-Fe-N alloys (rare earth magnets), Al-Ni-Co alloys (Alnico magnets), and ferrite. The ferrite may be, for example, spinel ferrite, hexagonal ferrite, or garnet ferrite. The metal powder may also be a copper alloy such as a Cu-Sn alloy, a Cu-Sn-P alloy, a Cu-Ni alloy, or a Cu-Be alloy. The metal powder may contain one of the above elements and compositions, or more of the above elements and compositions.

[0054] The metal powder may be pure Fe. The metal powder may be an alloy containing iron (Fe-based alloy). The Fe-based alloy may be, for example, an Fe-Si-Cr alloy or an Nd-Fe-B alloy. The metal powder may be at least one of amorphous iron powder and carbonyl iron powder. When the metal powder contains at least one of pure Fe and Fe-based alloy, it is easy to produce a molded body from the compound that has a high packing density and excellent magnetic properties. The metal powder may be an Fe amorphous alloy.

[0055] As commercially available Fe amorphous alloy powders, at least one selected from the group consisting of, for example, AW2-08, KUAMET-6B2, 9A4-II (all product names of Epson Atomics Corporation), DAP MS3, DAP MS7, DAP MSA10, DAP PB, DAP PC, DAP MKV49, DAP 410L, DAP 430L, DAP HYB series (all product names of Daido Steel Co., Ltd.), MH45D, MH28D, MH25D, and MH20D (all product names of Kobe Steel Ltd.) may be used.

[0056] Compounds are manufactured by mixing metal powder and a resin composition (each component constituting the resin composition) while heating. For example, the metal powder and resin composition may be kneaded using a kneader, rolls, or agitator while heating. Heating and mixing the metal powder and resin composition causes the resin composition to adhere to part or all of the surface of the metal element-containing particles constituting the metal powder, coating the particles, and causing part or all of the epoxy resin in the resin composition to become a semi-cured product. As a result, a compound is obtained. Alternatively, a compound may be obtained by further adding wax to the powder obtained by heating and mixing the metal powder and resin composition. The resin composition and wax may be mixed beforehand.

[0057] In the mixing process, metal powder, epoxy resin, curing agent, dispersant, curing accelerator, and coupling agent may be mixed in the tank. Alternatively, metal powder, dispersant, and coupling agent may be added to the tank and mixed, then epoxy resin, curing agent, and curing accelerator may be added to the tank and the raw materials in the tank may be mixed. Alternatively, metal powder, dispersant, epoxy resin, curing agent, and coupling agent may be mixed in the tank, then a curing accelerator may be added to the tank and the raw materials in the tank may be further mixed. Alternatively, a mixture of epoxy resin, curing agent, curing accelerator, and dispersant (resin mixture) may be prepared in advance, then metal powder and coupling agent may be mixed to prepare a metal mixture, and then the metal mixture and the above resin mixture may be mixed. If a release agent is used, it should be added at the same timing as the dispersant. If a siloxane compound is used, it should be added at the same timing as the coupling agent.

[0058] The mixing time depends on the type of mixing machine, the volume of the mixing machine, and the amount of compound to be produced, but it is preferably 1 minute or more, more preferably 2 minutes or more, and even more preferably 3 minutes or more. Furthermore, the mixing time is preferably 20 minutes or less, more preferably 15 minutes or less, and even more preferably 10 minutes or less. If the mixing time is less than 1 minute, mixing is insufficient, the moldability of the compound is impaired, and variations in the degree of hardening of the compound are likely to occur. If the mixing time exceeds 20 minutes, for example, the hardening of the resin composition (e.g., epoxy resin and curing agent) progresses in the tank, and the fluidity and moldability of the compound are likely to be impaired. When mixing the raw materials in the tank with a kneader while heating them, the heating temperature should be, for example, a temperature at which a semi-cured epoxy resin (B-stage epoxy resin) is produced and the production of a cured epoxy resin (C-stage epoxy resin) is suppressed. The heating temperature may be lower than the activation temperature of the curing accelerator. The heating temperature is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher. The heating temperature is preferably 150°C or lower, more preferably 120°C or lower, and even more preferably 110°C or lower. When the heating temperature is within the above range, the resin composition in the tank softens easily and coats the surface of the metal element-containing particles constituting the metal powder, a semi-cured epoxy resin is easily formed, and the complete curing of the epoxy resin during kneading is easily suppressed.

[0059] [Molded products and cured products] The molded body according to this embodiment may comprise the compound described above. The cured product according to this embodiment is obtained by curing the compound described above and may be included in the molded body. The molded body may comprise at least one selected from the group consisting of an uncured resin composition, a semi-cured resin composition (stage B resin composition), and a cured resin composition (stage C resin composition). The molded body according to this embodiment may be used as a encapsulant for electronic components or electronic circuit boards. This makes it possible to suppress cracks in the molded body caused by the difference in thermal expansion coefficients between the metal members of the electronic components or electronic circuit board and the molded body (encapsulant).

[0060] The molded body is manufactured by a manufacturing method that includes a step of pressurizing a compound in a mold. The manufacturing method for the molded body may include a step of pressurizing a compound that covers part or all of the surface of a metal member in a mold. The manufacturing method for the molded body may include only the step of pressurizing a compound in a mold, or it may include other steps in addition to this step. The manufacturing method for the molded body may include a first step, a second step, and a third step. The details of each step will be described below.

[0061] In the first step, the compound is prepared using the method described above.

[0062] In the second step, a molded body (a molded body in stage B) is obtained by pressurizing the compound in a mold. In the second step, a molded body (a molded body in stage B) may be obtained by pressurizing the compound that covers part or all of the surface of the metal member in a mold. In the second step, the resin composition is filled between the individual metal element-containing particles that make up the metal powder. The resin composition then functions as a binder, binding the metal element-containing particles together.

[0063] As a second step, transfer molding of the compound may be performed. In transfer molding, the compound may be pressurized at 3 MPa to 50 MPa. The higher the molding pressure, the easier it is to obtain a molded body with superior mechanical strength. Considering the mass productivity of the molded body and the lifespan of the mold, the molding pressure is preferably 8 MPa to 20 MPa. The density of the molded body formed by transfer molding may preferably be 75% to 86%, more preferably 80% to 86%, of the true density of the compound. When the density of the molded body is 75% to 86%, it is easier to obtain a molded body with superior mechanical strength. In transfer molding, the second and third steps may be performed together.

[0064] In the third step, the molded body is cured by heat treatment to obtain a molded body in stage C. The heat treatment temperature should be such that the resin composition in the molded body is sufficiently cured. Preferably, the heat treatment temperature is 100°C to 300°C, more preferably 110°C to 250°C. To suppress the oxidation of metal powder in the molded body, it is preferable to perform the heat treatment in an inert atmosphere. If the heat treatment temperature exceeds 300°C, the metal powder may be oxidized or the cured resin may deteriorate due to the trace amounts of oxygen inevitably contained in the heat treatment atmosphere. In order to sufficiently cure the resin composition while suppressing the oxidation of metal powder and the deterioration of the cured resin, the holding time of the heat treatment temperature may be preferably several minutes to 10 hours, more preferably 3 minutes to 8 hours. [Examples]

[0065] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited in any way by these examples.

[0066] The details of each component used in the preparation of the compounds in the examples and comparative examples are shown below.

[0067] (Epoxy resin) • Biphenylene aralkyl epoxy resin (product name: NC-3000, manufactured by Nippon Kayaku Co., Ltd.; epoxy equivalent: 275 g / eq) • Trifunctional epoxy resin (product name: VG3101L, manufactured by Printec Co., Ltd., epoxy equivalent: 212g / eq)

[0068] (Hardening agent) • Triphenylmethane-type phenolic resin (product name: MEHC-7500-3S, manufactured by Meiwa Chemicals Co., Ltd., hydroxyl group equivalent: 103 g / eq) • Biphenylene aralkyl type phenolic resin (product name: MEHC-7851SS, manufactured by Meiwa Kasei Co., Ltd., hydroxyl group equivalent: 202 g / eq)

[0069] (Curing accelerator) • Imidazole-based curing accelerator (product name: 2E4MZ, manufactured by Shikoku Chemicals Co., Ltd.)

[0070] (Coupling agent) • Methacryloxyoctyltrimethoxysilane (product name: KBM-5803, manufactured by Shin-Etsu Chemical Co., Ltd.) • 3-Glycidoxypropyltriethoxysilane (Product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0071] (Siloxane compounds) • Caprolactone-modified dimethyl silicone (product name: DBL-C32, manufactured by Gelest Corporation)

[0072] (Dispersant) The following phosphate esters having a group represented by "-OR" • R is a phosphate ester with 4 carbon atoms (product name: JP-504, manufactured by Johoku Chemical Industry Co., Ltd.) • R is a phosphate ester with 6 carbon atoms (product name: JP-506H, manufactured by Johoku Chemical Industry Co., Ltd.) • R is a phosphate ester with an 8-carbon organic group (product name: JP-508, manufactured by Johoku Chemical Industry Co., Ltd.) • R is a phosphate ester with 13 carbon atoms (product name: JP-513, manufactured by Johoku Chemical Industry Co., Ltd.)

[0073] (Release agent) • Partially saponified montanate wax (product name: LICOWAX-OP, manufactured by Clariant Chemicals Co., Ltd.) • Zinc stearate (product name: Zinc Stearate, manufactured by NOF Corporation)

[0074] (metal powder) • Amorphous iron powder (product name: 9A4-II, manufactured by Epson Atomics Corporation, average particle size 24 μm) • Amorphous iron powder (product name: AW2-08, manufactured by Epson Atomics Corporation, average particle size 5.3 μm)

[0075] [Compound preparation] (Examples) The epoxy resin, curing agent, curing accelerator, dispersant, and mold release agent shown in Table 1 were placed in a plastic container in the amounts (in grams) shown in the same table. A resin mixture was prepared by mixing these materials in the plastic container for 10 minutes. The resin mixture represents all components of the resin composition except for the coupling agent and siloxane compound.

[0076] Metal powder was prepared by uniformly mixing two types of amorphous iron powder shown in Table 1 for 5 minutes in a pressurized twin-screw kneader (manufactured by Nippon Spindle Manufacturing Co., Ltd., 5L capacity). The coupling agent and siloxane compound shown in Table 1 were added to the metal powder in the twin-screw kneader. Subsequently, the contents of the twin-screw kneader were heated to 90°C and mixed for 10 minutes while maintaining that temperature. Next, the above resin mixture was added to the contents of the twin-screw kneader, and the contents were melted and kneaded for 15 minutes while maintaining the temperature of the contents at 120°C. After the kneaded material obtained from the above melting and kneading was cooled to room temperature, the kneaded material was crushed with a hammer until it had a predetermined particle size. Note that "melting" above means the melting of at least a portion of the resin composition in the contents of the twin-screw kneader. The metal powder in the compound does not melt during the compound preparation process. The compound of the example was prepared by the above method.

[0077] (Comparative example) The comparative compound was prepared in the same manner as the examples, except that a dispersant was not used and the amount of metal powder was changed as shown in Table 1.

[0078] [Compound evaluation] The compounds obtained in the examples and comparative examples were evaluated as follows. The results are shown in Table 1.

[0079] (Flow properties: Minimum melt viscosity at 140°C) The minimum melt viscosity (in Pa·s) of the compound at 140°C was measured as described below. A CFT-100 (flow tester) manufactured by Shimadzu Corporation was used as the measuring device. A tablet was prepared from 7 g of the compound as the sample for measurement. The fluidity of the compound was evaluated under conditions of 140°C, 20 seconds of preheating, and a load of 100 kg. The plunger insertion distance (in mm) until the compound flow stopped was measured as the flow tester stroke. The time until the compound flow stopped was measured as the flow time. These measured values ​​were used as indicators of fluidity.

[0080] (Flow characteristics: 140°C disc flow) 5 g of compound (powder) was used as the sample for measurement. The 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 8 kg for 360 seconds, a roughly disc-shaped molded body made of the compound was formed. The temperature of the compound was maintained at 140°C during compression. 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 (unit: mm).

[0081] [Table 1]

Claims

1. A resin composition containing metal powder, epoxy resin, a curing agent, and a dispersant, The aforementioned metal powder is magnetic powder, The content of the aforementioned metal powder is 90% by mass or more and 98% by mass or less. The epoxy resin comprises a biphenylene aralkyl type epoxy resin and a polyfunctional epoxy resin containing two or more epoxy groups, which is different from the biphenylene aralkyl type epoxy resin. The curing agent comprises a triphenylmethane-type phenolic resin and a biphenylene aralkyl-type phenolic resin. A compound for molding a molded article, wherein the dispersant contains a phosphate ester.

2. The compound according to claim 1, wherein the phosphate ester has a group represented by -OR (where R represents an organic group having 4 or more carbon atoms).

3. The compound according to claim 2, wherein the organic group is an alkyl group having 4 or more carbon atoms, or a group in which an ether bond is inserted into at least a portion of the carbon-carbon bond in an alkyl group having 4 or more carbon atoms.

4. The compound according to claim 3, wherein the alkyl group and the group in which an ether bond is inserted into at least a portion of the carbon-carbon bond in the alkyl group have substituents.

5. The compound according to any one of claims 1 to 4, wherein the content of the dispersant is 1 part by mass or less per 100 parts by mass of the metal powder.

6. A molded article comprising the compound according to any one of claims 1 to 5.

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

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