JP7790348B2 - Compound, molded body, and cured product of the compound - Google Patents

Description

The present invention relates to a compound, a molded body, and a cured product of the compound.

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 wave shields (EMI shields), bonded magnets, etc. (See Patent Document 1 below).

JP 2014-13803 A

When industrial products are manufactured from compounds, the compound is supplied and filled into a mold through a channel, and components such as coils are embedded in the compound inside the mold. These processes require the compound to have good fluidity. Compound fluidity improves as the metal powder content in the compound decreases. However, to improve the magnetic properties of compounds used in inductors and other devices, a high metal powder content (filling rate) in the compound is desirable. However, as the metal powder content in the compound increases, the compound's melt viscosity increases, reducing its fluidity. Furthermore, during the heating process of a molded body made from the compound, cracks may form in the molded body. Therefore, compounds are required to have excellent fluidity during molding, as well as improved mechanical properties at high temperatures (e.g., high-temperature bending properties) of the molded body.

The present invention was made in consideration of the above circumstances, and aims to provide a compound that has excellent fluidity during molding and can form molded bodies with excellent mechanical properties at high temperatures, a molded body made from the compound, and a cured product of the compound.

A compound according to one aspect of the present invention comprises a resin composition containing metal powder, an epoxy resin, a curing agent, and a silane coupling agent, wherein the silane coupling agent contains a first silane compound having a functional group selected from an epoxy group, an amino group, a ureido group, and an isocyanate group, and a second silane compound having a chain hydrocarbon group having 6 or more carbon atoms, and the metal powder content is 90% by mass or more but less than 100% by mass.

A molded article according to one aspect of the present invention includes the above-described compound. A cured product according to one aspect of the present invention is a cured product of the above-described compound.

The present invention provides a compound that can form a molded body that has excellent fluidity during molding and excellent mechanical properties at high temperatures, a molded body made from the compound, and a cured product of the compound.

The following describes a preferred embodiment of the present invention. However, the present invention is not limited to the following embodiment.

[Compound]
The compound according to this embodiment includes a metal powder and a resin composition. The metal powder may contain, for example, at least one selected from the group consisting of an elemental metal, an alloy, an amorphous powder, and a metal compound. The resin composition contains at least an epoxy resin, a curing agent, and a coupling agent. The coupling agent includes a first silane compound having a functional group selected from an epoxy group, an amino group, a ureido group, and an isocyanate group, and a second silane compound having a chain hydrocarbon group having 6 or more carbon atoms. In the compound, the metal powder, the epoxy resin, the curing agent, and the coupling agent are mixed together. The resin composition may further contain other components such as a curing accelerator, a release agent, and an additive. The resin composition may include the epoxy resin, the curing agent, the coupling agent, the curing accelerator, the release agent, and the additive, and may be the remaining components (non-volatile components) excluding the organic solvent and the metal powder. The additive refers to the remaining components of the resin composition excluding the resin, the release agent, the curing agent, the curing accelerator, and the coupling agent. The additives are, for example, a flame retardant, a lubricant, etc. The compound may be a powder (compound powder).

The compound may comprise a metal powder and a resin composition adhered to the surface of each metal particle constituting the metal powder. The resin composition may cover the entire surface of the particle, or may cover only a portion of the surface of the particle. The compound may comprise an uncured resin composition and a metal powder. The compound may comprise a semi-cured resin composition (e.g., a B-stage resin composition) and a metal powder. The compound may comprise both an uncured resin composition and a semi-cured resin composition. The compound may consist of a metal powder and a resin composition.

The metal powder content in the compound is 90% by mass or more and less than 100% by mass of the total mass of the compound. If the metal powder content is too high, it becomes difficult to ensure the demoldability of the green body, and workability tends to be poor. From the viewpoint of the magnetic properties of the green body, the metal powder content is preferably 92% by mass or more, more preferably 94% by mass or more, even more preferably 95% by mass or more, and particularly preferably 96% by mass or more. The upper limit of the metal powder content may be 99% by mass or less, 98% by mass or less, or 97.5% by mass or less.

(Resin composition)
The resin composition functions as a binder for the metal particles that make up the metal powder, imparting mechanical strength to a molded body formed from the compound. For example, when the compound is molded under high pressure using a mold, the resin composition contained in the compound fills between the metal particles and binds the particles together. By curing the resin composition in the molded body, the cured resin composition more firmly binds the metal particles together, improving the mechanical strength of the molded body.

The resin composition according to this embodiment contains an epoxy resin as a thermosetting resin, thereby improving the fluidity of the compound. The epoxy resin may be, for example, a resin having two or more epoxy groups per molecule. There are no particular restrictions on the type of epoxy resin, and it can be selected depending on the desired properties of the composition.

Epoxy resins include, for example, biphenyl-type epoxy resins, stilbene-type epoxy resins, diphenylmethane-type epoxy resins, sulfur-containing epoxy resins, novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, salicylaldehyde-type epoxy resins, naphthol- and phenol-copolymerized epoxy resins, epoxidized aralkyl-type phenolic resins, bisphenol-type epoxy resins, epoxy resins containing a bisphenol skeleton, glycidyl ether-type epoxy resins of alcohols, glycidyl ether-type epoxy resins of paraxylylene and/or metaxylylene-modified phenolic resins, and terpene-modified phenolic resins. Examples of epoxy resins include glycidyl ether type epoxy resins of phenol 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 type 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 a peracid such as peracetic acid.

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, salicylic aldehyde novolac-type epoxy resins, and naphthol novolac-type epoxy resins.

In terms of mechanical strength, the epoxy resin may contain at least one selected from the group consisting of biphenylene aralkyl epoxy resins and orthocresol novolac epoxy resins.

The epoxy resin may be a crystalline epoxy resin. Although the molecular weight of a crystalline epoxy resin is relatively low, the crystalline epoxy resin has a relatively high melting point and excellent fluidity. The 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.

Commercially available crystalline epoxy resins include, for example, Epicron 860, Epicron 1050, Epicron 1055, Epicron 2050, Epicron 3050, Epicron 4050, Epicron 7050, Epicron HM-091, Epicron HM-101, Epicron N-730A, Epicron N-740, Epicron N-770, and Epicron N- 775, Epicron N-865, Epicron HP-4032D, Epicron HP-7200L, Epicron HP-7200, Epicron HP-7200H, Epicron HP-7200HH, Epicron HP-7200HHH, Epicron HP-4700, Epicron HP-4710, Epicron HP-4770, Epicron HP-5000, Epicron HP-6000, N500P-2, and N500P-10 (all product names manufactured by DIC Corporation); NC-3000, NC-3000-L, NC-3000-H, NC-310 0, CER-3000-L, NC-2000-L, XD-1000, NC-7000-L, NC-7300-L, EPPN-501H, EPPN-501HY, EPPN-50 2H, EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, CER-1020, EPPN-201, BREN-S, and BREN-10S (all of which are trade names manufactured by Nippon Kayaku Co., Ltd.); and YX-4000, YX-4000H, YL4121H, and YX-8800 (all of which are trade names manufactured by Mitsubishi Chemical Corporation).

The resin composition may contain one type of epoxy resin from the above. The resin composition may also contain multiple types of epoxy resins from the above. Among the above epoxy resins, the resin composition may contain an epoxy resin containing a biphenyl skeleton, an orthocresol novolac epoxy resin, or a multifunctional epoxy resin containing two or more epoxy groups.

Curing agents are classified into those that cure epoxy resins at low to room temperatures, and heat-curing curing agents that cure epoxy resins when heated. Examples of curing agents that cure epoxy resins at low to room temperatures include aliphatic polyamines, polyaminoamides, and polymercaptans. Examples of heat-curing curing agents include aromatic polyamines, acid anhydrides, phenolic novolac resins, and dicyandiamide (DICY). There are no particular restrictions on the type of curing agent, and it can be selected depending on the desired properties of the composition.

When a curing agent that cures epoxy resins at temperatures ranging from low to room temperature is used, the glass transition point of the cured epoxy resin tends to be low and the cured epoxy resin tends to be soft. As a result, molded articles formed from the compound also tend to be soft. On the other hand, from the perspective of improving the heat resistance of the molded article, the curing agent is preferably a heat-curing curing agent, more preferably a phenolic resin, and even more preferably a phenolic novolac resin. In particular, using a phenolic novolac resin as the curing agent makes it 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 article are likely to be improved.

The phenolic resin may include at least one selected from the group consisting of aralkyl phenolic resins, dicyclopentadiene phenolic resins, salicylaldehyde phenolic resins, novolac phenolic resins, copolymerized phenolic resins of benzaldehyde phenols and aralkyl phenols, paraxylylene and/or metaxylylene-modified phenolic resins, melamine-modified phenolic resins, terpene-modified phenolic resins, dicyclopentadiene naphthol resins, cyclopentadiene-modified phenolic resins, polycyclic aromatic ring-modified phenolic resins, biphenyl phenolic resins, and triphenylmethane phenolic resins. The phenolic resin may also be a copolymer composed of two or more of the above. Commercially available phenolic resins include, for example, Tamanol 758 manufactured by Arakawa Chemical Industries, Ltd. and HP-850N manufactured by Hitachi Chemical Co., Ltd.

Phenol novolac resins may be resins obtained by, for example, 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.

The curing agent may be, for example, a compound having two phenolic hydroxyl groups per molecule. The compound having two phenolic hydroxyl groups per 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.

The resin composition may contain one type of phenolic resin from among the above. The resin composition may contain multiple types of phenolic resins from among the above. The resin composition may contain one type of curing agent from among the above. The resin composition may contain multiple types of curing agents from among the above.

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 molded articles formed from the compound after curing tends to decrease. However, the effects of the present invention can be obtained even if the ratio of active groups in the curing agent is outside the above range.

The coupling agent improves adhesion between the resin composition and the metal element-containing particles that make up the metal powder, thereby improving the flexibility and mechanical strength of molded articles formed from the compound. The resin composition of this embodiment contains a specific silane compound as a coupling agent, thereby improving the fluidity and curing characteristics of the compound. The coupling agent includes a first silane compound having a functional group selected from an epoxy group, an amino group, a ureido group, and an isocyanate group, and a second silane compound having a chain hydrocarbon group with six or more carbon atoms. In this specification, a chain hydrocarbon group with six or more carbon atoms may be referred to as a long-chain hydrocarbon group.

By including the first silane compound in the resin composition, a molded article with excellent high-temperature bending properties can be formed. The functional group possessed by the first silane compound can react with the epoxy resin or the curing agent. The first silane compound is a silane compound that does not have a long-chain hydrocarbon group.

Examples of the first silane compound having an epoxy group include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane.

Examples of the first silane compound having an amino group include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, N-phenyl-3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropylmethyldiethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

Examples of the first silane compound having a ureido group include 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-ureidopropylmethyldimethoxysilane, and 3-ureidopropylmethyldiethoxysilane.

Examples of the first silane compound having an isocyanate group include 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-isocyanatepropylmethyldimethoxysilane, and 3-isocyanatepropylmethyldiethoxysilane.

In order to further improve high-temperature bending properties, the content of the first silane compound may be 0.5 parts by mass or more and 10 parts by mass or less, 1.0 parts by mass or more and 8.0 parts by mass or less, or 2.0 parts by mass or more and 7.0 parts by mass or less per 100 parts by mass of epoxy resin.

The inclusion of a second silane compound in the resin composition can improve the fluidity of the compound during molding. The number of carbon atoms in the chain hydrocarbon group of the second silane compound is 6 or more, or may be 7 or more or 8 or more, and may be 20 or less, 16 or less, or 14 or less. The second silane compound may have a styryl group, a (meth)acryloyl group, or a vinyl group.

Examples of the second silane compound include hexyltrimethoxysilane, hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, acryloxyhexyltrimethoxysilane, acryloxyhexyltriethoxysilane, methacryloxyhexyltrimethoxysilane, methacryloxyhexyltriethoxysilane, acryloxyheptyltrimethoxysilane, acryloxyheptyltriethoxysilane, methacryloxyheptyltrimethoxysilane, methacryloxyheptyltriethoxysilane, acryloxyoctyltrimethoxysilane, acryloxyoctyltriethoxysilane, methacryloxyoctyltrimethoxysilane, and methacryloxyoctyltriethoxysilane.

In order to further improve fluidity, the content of the second silane compound may be 0.1 parts by mass or more and 5.0 parts by mass or less, 0.5 parts by mass or more and 4.0 parts by mass or less, or 1.0 parts by mass or more and 3.0 parts by mass or less per 100 parts by mass of the epoxy resin.

The coupling agent may further include a third silane compound having a mercapto group. The third silane compound is a silane compound that does not have a long-chain hydrocarbon group. Examples of the third silane compound include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropylmethyldithoxysilane.

From the viewpoint of achieving both fluidity and mechanical properties, the content of the coupling agent may be 1.0 parts by mass or more and 20 parts by mass or less, 2.0 parts by mass or more and 15 parts by mass or less, or 3.0 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the epoxy resin.

The curing accelerator is not limited to any particular composition, as long as it reacts with the 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 including a curing accelerator in the resin composition, the moldability and releasability of the compound can be improved. Furthermore, by including a curing accelerator in the resin composition, the mechanical strength of molded articles (e.g., electronic components) produced using the compound can be improved, and the storage stability of the compound in high-temperature, high-humidity environments can be improved.

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

Commercially available imidazole curing accelerators include 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 manufactured by Shikoku Chemicals Corporation).

Urea-based curing accelerators are not particularly limited as long as they contain a urea group, but from the perspective of improving storage stability, alkylurea-based curing accelerators containing an alkylurea group are preferred. Examples of alkylurea-based curing accelerators containing an alkylurea group include aromatic alkylureas and aliphatic alkylureas. Commercially available alkylurea-based curing accelerators include U-CAT3512T (trade name, manufactured by San-Apro Co., Ltd., aromatic dimethylurea) and U-CAT3513N (trade name, manufactured by San-Apro Co., Ltd., aliphatic dimethylurea). Of these, aromatic alkylureas are preferred because they have a moderately low cleavage temperature and facilitate efficient curing of the compound.

The amount of curing accelerator used is not particularly limited, as long as it achieves a curing acceleration effect. To improve the curing and fluidity of the resin composition upon moisture absorption, the amount of curing accelerator used is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1.0 to 10 parts by mass, per 100 parts by mass of epoxy resin. A curing accelerator content of 0.1 parts by mass or more is likely to provide a sufficient curing acceleration effect. A curing accelerator content of 30 parts by mass or less is unlikely to reduce the storage stability of the compound. The amount of curing accelerator used is preferably 0.001 to 5 parts by mass, per 100 parts by mass of the combined weight of the epoxy resin and phenolic resin. However, the effects of the present invention can be achieved even if the amount and content of the curing accelerator used are outside the above ranges.

The resin composition may contain a compound having a siloxane bond (siloxane compound) as an additive, as this tends to reduce the molding shrinkage of the compound and 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 by -Si-O-Si-. The compound having a siloxane bond may be a polysiloxane compound.

The content of the siloxane compound may be 1 part by mass or more and 50 parts by mass or less, 5 parts by mass or more and 45 parts by mass or less, or 10 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the epoxy resin.

The compound may contain a flame retardant to improve the compound's environmental safety, recyclability, moldability, and low cost. The flame retardant may be, for example, at least one selected from the group consisting of bromine-based 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 or more of the above flame retardants.

When a molded article is formed from the compound using a mold, the resin composition may contain wax. The wax increases the fluidity of the compound during molding (e.g., transfer molding) and also functions as a mold release agent. The wax may be at least one of a fatty acid, such as a higher fatty acid, and a fatty acid ester.

Waxes include, for example, fatty acids such as montanic acid, stearic acid, 12-hydroxystearic acid, and lauric acid, or their esters; fatty acid salts such as zinc stearate, calcium stearate, barium stearate, aluminum stearate, magnesium stearate, calcium laurate, zinc laurate, zinc linoleate, calcium ricinoleate, and zinc 2-ethylhexanoate; and fatty acid salts such as stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, palmitic acid amide, lauric acid amide, hydroxystearic acid amide, methylene bisstearic acid amide, ethylene bisstearic acid amide, ethylene bislauric acid amide, distearyl adipamide, ethylene bisoleic acid amide, dioleyl adipamide, and N-stearyl stearyl. fatty acid esters such as butyl stearate; alcohols such as ethylene glycol and stearyl alcohol; polyethers such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol and modified products thereof; polysiloxanes such as silicone oil and silicone grease; fluorine compounds such as fluorine-based oil, fluorine-based grease and fluorine-containing resin powder; and waxes such as paraffin wax, polyethylene wax, amide wax, polypropylene wax, ester wax, carnauba wax and microwax.

In order to achieve both fluidity and releasability, the wax content may be 1 part by mass or more and 20 parts by mass or less, 2 parts by mass or more and 15 parts by mass or less, or 3 parts by mass or more and 10 parts by mass or less per 100 parts by mass of epoxy resin.

(metal powder)
The metal powder (metal element-containing particle) may contain, for example, at least one selected from the group consisting of a simple metal, an alloy, and a metal compound. The metal element-containing powder may be, for example, at least one selected from the group consisting of a simple metal, an alloy, and a metal compound. The alloy may include at least one selected from the group consisting of a solid solution, a eutectic, and an intermetallic compound. The alloy may be, for example, stainless steel (Fe-Cr alloy, Fe-Ni-Cr alloy, etc.). The metal compound may be, for example, an oxide such as ferrite. The metal powder may contain one metal element or multiple metal elements. The metal element contained in the metal powder may be, for example, a base metal element, a noble metal element, a transition metal element, or a rare earth element. The compound may contain one metal element-containing powder, or multiple metal element-containing powders with different compositions.

The metal element contained in the metal powder may be at least one selected from the group consisting of iron (Fe), copper (Cu), titanium (Ti), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), tin (Sn), chromium (Cr), niobium (Nb), barium (Ba), strontium (Sr), lead (Pb), silver (Ag), praseodymium (Pr), neodymium (Nd), samarium (Sm), and dysprosium (Dy). From the perspective of improving magnetic properties, the metal powder preferably contains at least one metal element selected from the group consisting of iron, cobalt, and nickel. The metal powder may further contain elements other than the metal element. The metal powder may contain, for example, carbon (C), oxygen (O), beryllium (Be), phosphorus (P), sulfur (S), boron (B), or silicon (Si).

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, for example, a magnetic powder consisting of at least one material selected from the group consisting of an Fe-Si alloy, an Fe-Si-Al alloy (Sendust), an Fe-Ni alloy (Permalloy), an Fe-Cu-Ni alloy (Permalloy), an Fe-Co alloy (Permendur), an Fe-Cr-Si alloy (electromagnetic stainless steel), an Nd-Fe-B alloy (rare earth magnet), an Sm-Fe-N alloy (rare earth magnet), an Al-Ni-Co alloy (Alnico magnet), and a ferrite. The ferrite may be, for example, a spinel ferrite, a hexagonal ferrite, or a garnet ferrite. The metal powder may 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 may contain a plurality of the above elements and compositions.

The metal powder may be Fe alone. 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 element-containing powder may be at least one of amorphous iron powder and carbonyl iron powder. When the metal powder contains at least one of Fe alone and an Fe-based alloy, it is easy to produce a compact from the compound that has a high space factor and excellent magnetic properties. The metal powder may be an Fe-amorphous alloy.

Commercially available Fe amorphous alloy powders may include, for example, at least one selected from the group consisting of AW2-08, KUAMET-6B2 (all trade names manufactured by Epson Atmix Corporation), DAP MS3, DAP MS7, DAP MSA10, DAP PB, DAP PC, DAP MKV49, DAP 410L, DAP 430L, DAP HYB series (all trade names manufactured by Daido Steel Co., Ltd.), MH45D, MH28D, MH25D, and MH20D (all trade names manufactured by Kobe Steel, Ltd.).

<Compound manufacturing method>
In producing the compound, the metal powder and the resin composition (each component constituting the resin composition) are mixed while being heated. For example, the metal powder and the resin composition may be kneaded using a kneader, roll, agitator, or the like while being heated. By heating and mixing the metal powder and the resin composition, the resin composition adheres to part or all of the surface of the metal element-containing particles constituting the metal powder, coating the metal element-containing particles, and part or all of the epoxy resin in the resin composition becomes semi-cured. As a result, the compound is obtained. The compound may also be obtained by further adding wax to the powder obtained by heating and mixing the metal powder and the resin composition. The resin composition and wax may be mixed in advance.

In the kneading process, the metal powder, epoxy resin, curing agent, curing accelerator, and coupling agent may be kneaded in a tank. After the metal powder and coupling agent are introduced into the tank and mixed, the epoxy resin, curing agent, and curing accelerator may be introduced into the tank and the raw materials in the tank may be kneaded. After the siloxane compound, epoxy resin, curing agent, and coupling agent are kneaded in the tank, the curing accelerator may be introduced into the tank and the raw materials in the tank may be further kneaded. Alternatively, a mixed powder of epoxy resin, curing agent, and curing accelerator (resin mixed powder) may be prepared in advance, and then the metal powder and coupling agent may be kneaded to prepare the metal mixed powder, and then the metal mixed powder and the above-mentioned resin mixed powder may be kneaded.

The mixing time depends on the type of mixing machine, the capacity of the mixing machine, and the amount of compound produced, but is preferably at least 1 minute, more preferably at least 2 minutes, and even more preferably at least 3 minutes. 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, the mixing will be insufficient, the compound's moldability will be impaired, and the compound's degree of cure will vary. If the mixing time exceeds 20 minutes, for example, the resin composition (e.g., epoxy resin and phenolic resin) will harden rapidly in the tank, which will likely impair the compound's fluidity and moldability.

When the raw materials in the tank are heated and kneaded in a kneader, the heating temperature may 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, for example, 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 and tends to coat the surfaces of the metal element-containing particles that make up the metal powder, which tends to produce a semi-cured epoxy resin and suppress complete curing of the epoxy resin during kneading.

[Molded body]
The molded article according to this embodiment may include the above-described compound. The molded article according to this embodiment may include a cured product of the above-described compound. The molded article may include at least one selected from the group consisting of an uncured resin composition, a semi-cured product of the resin composition (a B-stage resin composition), and a cured product of the resin composition (a C-stage resin composition). The molded article according to this embodiment may be used as an encapsulant for electronic components or electronic circuit boards. According to this embodiment, cracks in the molded article caused by the difference in thermal expansion coefficient between the metal member of the electronic component or electronic circuit board and the molded article (encapsulant) can be suppressed.

The cured product of the compound is a cured product of metal powder and a resin composition, and the metal powder content is 90% by mass or more but less than 100% by mass. The flexural strength of the cured product at 250°C is preferably 7.0 MPa or more, more preferably 8.0 MPa or more, and even more preferably 8.5 MPa or more, from the viewpoint of increasing the strength of the cured product. The upper limit of the flexural strength is approximately 10 MPa. The flexural modulus of the cured product at 250°C may be 1.3 GPa or less, 1.2 GPa or less, or 1.1 GPa or less, from the viewpoint of imparting flexibility to the cured product. The lower limit of the flexural modulus is approximately 0.1 GPa. The value obtained by dividing the flexural strength (MPa) at 250°C by the flexural modulus (GPa) at 250°C can be used as an index of the reliability of the cured product. This index is preferably 9.0 x ^10-3 or more, more preferably 9.2 x ^10-3 or more, and even more preferably 10.4 x ^10-3 or more. The upper limit of this index is not particularly limited, and may be, for example, 5×10 ⁻² or less.

<Method of manufacturing molded body>
The method for producing a molded body according to this embodiment may include a step of pressurizing a compound in a mold. The method for producing a molded body may include a step of pressurizing a compound that covers a part or the entire surface of a metal member in a mold. The method for producing a molded body may include only the step of pressurizing a compound in a mold, or may include other steps in addition to the step. The method for producing a molded body may include a first step, a second step, and a third step. Each step will be described in detail below.

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

In the second step, the compound is pressed in a mold to obtain a molded body (B-stage molded body). In the second step, the compound that covers part or all of the surface of the metal component may be pressed in a mold to obtain a molded body (B-stage molded body). In the second step, a resin composition is filled between the individual metal element-containing particles that make up the metal element-containing powder. The resin composition then functions as a binding material (binder) to bind the metal element-containing particles together.

In the second step, transfer molding of the compound may be performed. In transfer molding, the compound may be pressurized at 5 MPa or more and 50 MPa or less. The higher the molding pressure, the easier it is to obtain a molded product with excellent mechanical strength. When considering the mass productivity of the molded product and the life of the mold, the molding pressure is preferably 8 MPa or more and 20 MPa or less. The density of the molded product formed by transfer molding may preferably be 75% or more and 86% or less, more preferably 80% or more and 86% or less, of the true density of the compound. When the density of the molded product is 75% or more and 86% or less, a molded product with excellent mechanical strength is more likely to be obtained. In transfer molding, the second and third steps may be performed together.

In the third step, the molded body is cured by heat treatment to obtain a C-stage molded body. The heat treatment temperature may be any temperature that sufficiently cures the resin composition in the molded body. The heat treatment temperature may be preferably 100°C or higher and 300°C or lower, more preferably 110°C or higher and 250°C or lower. To suppress oxidation of the metal powder in the molded body, the heat treatment is preferably performed 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. To sufficiently cure the resin composition while suppressing oxidation of the metal powder and deterioration of the cured resin, the heat treatment temperature may be maintained for a period of preferably several minutes to 10 hours, more preferably 3 minutes to 8 hours.

The present invention will be explained in more detail below using examples and comparative examples, but the present invention is not limited to these examples in any way.

Details of each component used in preparing the compounds of the examples and comparative examples are shown below.

(epoxy resin)
Biphenylene aralkyl epoxy resin (trade name: NC-3000, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 275 g/eq)
Multifunctional epoxy resin (product name: TECHMORE VG3101L, manufactured by Printec Co., Ltd., epoxy equivalent: 215 g/eq)

(hardening agent)
Triphenylmethane phenolic resin (product name: HE910-09, manufactured by Air Water Inc., hydroxyl group equivalent: 101 g/eq)
Biphenylene aralkyl phenolic resin (trade name: MEHC-7841-4S, manufactured by Meiwa Kasei Co., Ltd., hydroxyl group equivalent: 166 g/eq)

(Coupling Agent)
3-glycidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)
3-mercaptopropyltrimethoxysilane (trade name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.)
Methacryloxyoctyltrimethoxysilane (trade name: KBM-5803, manufactured by Shin-Etsu Chemical Co., Ltd.)

(Curing accelerator)
Imidazole-based curing accelerator (product name: 2P4MHZ-PW, manufactured by Shikoku Chemicals Corporation)
(Release agent)
Zinc laurate (product name: Powder Base L, manufactured by NOF Corporation)
Partially saponified Montan acid ester wax (trade name: Licowax-OP, manufactured by Clariant Chemicals Co., Ltd.)
(Additives)
Caprolactone-modified dimethyl silicone (trade name: DBL-C32, manufactured by Gelest Co., Ltd.)

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

[Compound Preparation]
Examples 1 to 5
The epoxy resin, curing agent, curing accelerator, and release agent shown in Table 1 were placed in a plastic container in the amounts (unit: g) shown in the table. These materials were mixed in the plastic container for 10 minutes to prepare a resin mixture. The resin mixture corresponds to all components of the resin composition except for the coupling agent and additives.

The two types of amorphous iron powder shown in Table 1 were uniformly mixed in a pressure-type twin-screw kneader (Nihon Spindle Manufacturing Co., Ltd., 5 L capacity) for 5 minutes to prepare a metal powder. The coupling agent and additives shown in Table 1 were added to the metal powder in the twin-screw kneader. The contents of the twin-screw kneader were then heated to 90°C and mixed for 10 minutes while maintaining that temperature. The resin mixture was then added to the contents of the twin-screw kneader, and the contents were melted and kneaded for 15 minutes while maintaining the temperature at 120°C. The resulting mixture was cooled to room temperature and then pulverized with a hammer until it reached the specified particle size. Note that "melting" in this context refers to the melting of at least a portion of the resin composition in the twin-screw kneader. The metal powder in the compound did not melt during the compound preparation process. The compounds of Examples 1 to 5 were prepared using the above method.

(Comparative Examples 1 to 3)
Compounds of Comparative Examples 1 to 3 were prepared in the same manner as in Examples, except that the types and amounts of each component were changed as shown in Table 2.

[Compound evaluation]
The compounds obtained in the examples and comparative examples were evaluated as follows, and the results are shown in Tables 1 and 2.

(Liquidity)
The fluidity evaluation was carried out using a flow tester CFT-100 manufactured by Shimadzu Corporation. 7 g of the compound was molded to prepare a tablet. Using the tablet, the fluidity was evaluated under the conditions of 130°C, preheating for 20 seconds, and a load of 100 kg. The plunger depression distance (unit: mm) until the flow of the compound stopped was defined as the flow tester stroke, and the time until the flow of the compound stopped was measured as the flow time, which was used as an index of fluidity.

(Gel time)
The gel time of the compound was measured by the following method. Using a Curastometer (manufactured by JSR Trading Co., Ltd.), the gel time was measured under the conditions of a sample amount of 1.5 mL and 140°C. The time at which the torque on the obtained chart started to rise was taken as the gel time. A shorter gel time indicates higher curability.

(Bending test)
The compound was transfer molded under conditions of a mold temperature of 140°C, a molding pressure of 13.5 MPa, and a curing time of 360 seconds, and then post-cured at 180°C for 2 hours to obtain a test specimen, which measured 80 mm in length, 10 mm in width, and 3.0 mm in thickness.

A three-point support bending test was carried out on the test specimen at 250°C using an autograph equipped with a thermostatic bath. The autograph used was an AGS-500A manufactured by Shimadzu Corporation. In the bending test, one side of the test specimen was supported by two supports. A load was applied to the other side of the test specimen at the center position between the two supports. The load at which the test specimen broke was measured. The measurement conditions for the bending test were as follows:
Distance between two fulcrums Lv: 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)

The bending strength σ (unit: MPa) was calculated based on the following formula (A). The bending modulus E (unit: GPa) was calculated based on the following formula (B). In the formulas below, "P" is the load (unit: N) when the test piece breaks. "Lv" is the distance between two supports (unit: mm). "W" is the width of the test piece (unit: mm). "t" is the thickness of the test piece (unit: mm). "F/Y" is the gradient of the linear portion of the load-deflection curve (unit: N/mm).
σ=(3×P×Lv)/(2×W× ^t2 ) (A)
E=[ ^Lv3 /(4×W× ^t3 )]×(F/Y) (B)

(Reliability)
The value obtained by dividing the bending strength (MGa) at 250° C. by the bending modulus (GPa) at 250° C. was used as an index for evaluating reliability. A larger value indicates a better balance between strength and modulus.

(reflow processing)
A copper metal member was sealed with a compound by transfer molding, and the compound was hardened to obtain a molded body. The molded body was subjected to a reflow treatment. The maximum heating temperature in the reflow treatment was 260°C. The heating time was 300 seconds. After the reflow treatment, the molded body was observed to check for the presence or absence of cracks in the molded body. "A" in the table means that no cracks were formed in the molded body, and "B" means that cracks were formed in the molded body.

Claims (7)

The metal powder and a resin composition containing an epoxy resin, a curing agent, and a coupling agent are included,
the coupling agent comprises a first silane compound having a functional group selected from an epoxy group, an amino group, a ureido group, and an isocyanate group, a second silane compound having a styryl group, a (meth)acryloyl group, or a vinyl group and a chain hydrocarbon group having 6 or more carbon atoms , and a third silane compound having a mercapto group ;
The compound has a metal powder content of 90% by mass or more and less than 100% by mass. The compound of claim 1 , wherein the first silane compound has an epoxy group. 3. The compound according to claim 1, wherein the content of the coupling agent is 1.0 part by mass or more and 20 parts by mass or less per 100 parts by mass of the epoxy resin. 4. The compound according to claim 1 , wherein the metal powder contains at least one metal element selected from the group consisting of iron, cobalt, and nickel. The compound according to any one of claims 1 to 4 , wherein the metal powder is a magnetic powder. A molded article comprising the compound according to any one of claims 1 to 5 . A cured product of the compound according to any one of claims 1 to 5 .