TWI891891B - Composite, molded body, and cured composite - Google Patents

Abstract

One aspect of the present invention provides a composite comprising metal powder and a resin composition containing an epoxy resin, a curing agent, and a coupling agent. The coupling agent comprises a first silane compound and a second silane compound. The first silane compound has a functional group selected from an epoxy group, an amine group, a urea group, and an isocyanate group. The second silane compound has a chain hydrocarbon group with at least 6 carbon atoms. The metal powder content is at least 90% by mass and less than 100% by mass.

Description

Composite, molded body, and cured composite

The present invention relates to a composite, a formed body, and a cured product of the composite.

Composites composed of metal powder and resin compositions are used as raw materials for various industrial products due to the various physical properties of the metal powder. For example, composites are used as raw materials for inductors, sealing materials, electromagnetic shielding (EMI shielding), and bonded magnets (see Patent Document 1 below).

[Patent Document 1] Japanese Patent Application Laid-Open No. 2014-13803

When manufacturing industrial products from a composite, the composite is fed through a flow path and filled into a mold, or parts such as coils are embedded in the composite within the mold. These steps require the composite to have excellent fluidity. The composite's fluidity improves as the metal powder content in the composite decreases. However, to improve the magnetic properties of composites used in inductors and other applications, a high metal powder content (filling ratio) is desirable. However, as the metal powder content in the composite increases, the composite's melt viscosity increases, decreasing the composite's fluidity. Furthermore, during the heating step of the composite molded body, cracks may form in the molded body. Therefore, the composite is required to have excellent fluidity during molding and to improve the mechanical properties of the molded body at high temperatures (e.g., high-temperature bending properties).

The present invention has been made in view of the above circumstances, and its object is to provide a composite material capable of forming a molded body having excellent fluidity during molding and excellent mechanical properties at high temperatures, a molded body using the composite material, and a cured product of the composite material.

One aspect of the present invention provides a composite comprising metal powder and a resin composition containing an epoxy resin, a curing agent, and a silane coupling agent. The silane coupling agent comprises a first silane compound and a second silane compound. The first silane compound has a functional group selected from an epoxy group, an amine group, a urea group, and an isocyanate group. The second silane compound has a chain hydrocarbon group with at least 6 carbon atoms. The metal powder content is 90% by mass or more and less than 100% by mass.

The molded article on one side of the present invention comprises the aforementioned composite. The cured product on one side of the present invention is a cured product of the aforementioned composite. [Effects of the Invention]

According to the present invention, a composite material capable of forming a molded body having excellent fluidity during molding and excellent mechanical properties at high temperatures, a molded body using the composite material, and a cured product of the composite material can be provided.

Hereinafter, preferred embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments.

[Compound] The complex of this embodiment comprises metal powder and a resin composition. The metal powder may contain, for example, at least one selected from the group consisting of metal monomers, alloys, amorphous powders, and metal compounds. The resin composition contains at least an epoxy resin, a curing agent, and a coupling agent. The coupling agent comprises a first silane compound having a functional group selected from an epoxy group, an amine group, a urea group, and an isocyanate group, and a second silane compound having a chain hydrocarbon group having 6 or more carbon atoms. The metal powder, epoxy resin, curing agent, and coupling agent are mixed in the complex. The resin composition may further contain a curing accelerator, a mold release agent, an additive, and the like as other components. The resin composition may include an epoxy resin, a curing agent, a coupling agent, a curing accelerator, a mold release agent, and additives, excluding the remaining components (non-volatile components) other than the organic solvent and metal powder. Additives are the remaining components in the resin composition other than the resin, mold release agent, curing agent, curing accelerator, and coupling agent. Examples of additives include flame retardants and lubricants. The compound may be in the form of a powder (compound powder).

The composite may comprise metal powder and a resin composition attached to the surface of each metal particle comprising the metal powder. The resin composition may cover the entire surface of the particle or only a portion of the surface. The composite may also comprise an uncured resin composition and metal powder. The composite may also comprise a semi-cured resin composition (e.g., a resin composition in the B-stage) and metal powder. The composite may also comprise both an uncured resin composition and a semi-cured resin composition. The composite may also be formed from metal powder and a resin composition.

The metal powder content in the composite can be 90% by mass or greater and less than 100% by mass relative to the overall composite mass. If the metal powder content increases, it becomes difficult to ensure mold release properties of the formed body, and workability tends to deteriorate. From the perspective of the magnetic properties of the formed body, the metal powder content is preferably 92% by mass or greater, more preferably 94% by mass or greater, even more preferably 95% by mass or greater, and particularly preferably 96% by mass or greater. The upper limit of the metal powder content can 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 binding material (binder) for the metal particles that comprise the metal powder, imparting mechanical strength to the resulting composite molded body. For example, when the composite is molded under high pressure using a mold, the resin composition within the composite fills the spaces between the metal particles, bonding them together. Curing the resin composition within the molded body further strengthens the bonds between the metal particles, enhancing the mechanical strength of the molded body.

The resin composition of this embodiment includes an epoxy resin as a thermosetting resin, thereby enhancing the fluidity of the composite. The epoxy resin may, for example, contain two or more epoxy groups per molecule. The type of epoxy resin is not particularly limited and can be selected based on the desired properties of the composition.

Examples of epoxy resins include biphenyl epoxy resins, stilbene epoxy resins, diphenylmethane epoxy resins, sulfur-containing epoxy resins, novolac epoxy resins, dicyclopentadiene epoxy resins, salicylic aldehyde epoxy resins, naphthol-phenol copolymer epoxy resins, aralkyl phenolic resin epoxides, bisphenol epoxy resins, bisphenol skeleton-containing epoxy resins, alcohol epoxy propyl ether epoxy resins, para- and/or inter-modified phenolic resin epoxy propyl ether epoxy resins, terpene-modified phenolic resins. epoxy resins of epoxy propyl ether type, epoxy resins of cyclopentadiene type, epoxy resins of epoxy propyl ether type of polycyclic aromatic modified phenolic resin, epoxy resins of epoxy propyl ether type of phenolic resin containing naphthalene ring, epoxy propyl ester type epoxy resin, epoxy propyl type or methyl epoxy propyl type Epoxy resins, aliphatic epoxy resins, halogenated phenol novolac epoxy resins, o-cresol novolac epoxy resins, hydroquinone epoxy resins, trihydroxymethylpropane epoxy resins, and linear aliphatic epoxy resins obtained by oxidizing olefinic bonds with peracids such as peracetic acid.

From the viewpoint of fluidity, the epoxy resin may include at least one selected from the group consisting of biphenyl-type epoxy resins, o-cresol novolac-type epoxy resins, phenol novolac-type epoxy resins, bisphenol-type epoxy resins, epoxy resins having a bisphenol skeleton, salicylic novolac-type epoxy resins, and naphthol novolac-type epoxy resins.

From the viewpoint of mechanical strength, the epoxy resin may include at least one selected from the group consisting of biphenylene aralkyl type epoxy resins and o-cresol novolac type epoxy resins.

The epoxy resin may be a crystalline epoxy resin. Although crystalline epoxy resins have a relatively low molecular weight, they have a relatively high melting point and excellent fluidity. Crystalline epoxy resins (highly crystalline epoxy resins) 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 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 trade names manufactured by DIC Corporation); NC-3000, NC-3000-L, NC-3000-H, NC-3100, CER-3000-L, NC-2000-L, XD-1000, NC-7000-L, NC-7300-L, EPPN-501H, EPPN-501HY, EPPN-502H, EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, CER-1020, EPPN-201, BREN-S, and BREN-10S (all trade names manufactured by Nippon Kayaku Co., Ltd.); YX-4000, YX-4000H, YL4121H, and YX-8800 (all trade names manufactured by Mitsubishi Chemical Corporation).

The resin composition may contain one of the aforementioned epoxy resins. Alternatively, the resin composition may contain a plurality of the aforementioned epoxy resins. Among the aforementioned epoxy resins, the resin composition may also contain an epoxy resin containing a biphenyl backbone, an o-cresol novolac-type epoxy resin, or a multifunctional epoxy resin containing two or more epoxy groups.

Curing agents are categorized into two types: those that cure epoxy resins at temperatures ranging from low to room temperature, and heat-curing curing agents that cure epoxy resins upon heating. Examples of curing agents that cure epoxy resins at temperatures ranging from low to room temperature include aliphatic polyamines, polyaminoamides, and polythiols. 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 based on the desired properties of the composition.

When a curing agent that cures epoxy resin at temperatures ranging from low temperatures to room temperature is used, 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 composite also tends to become soft. On the other hand, from the perspective of improving the heat resistance of the molded body, the curing agent is preferably a heat-curing curing agent, more preferably a phenolic resin, and even more preferably a phenol novolac resin. In particular, by using a phenol novolac resin as a curing agent, it is easy 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 are easily improved.

The phenolic resin may include, for example, at least one selected from the group consisting of aralkyl phenolic resins, dicyclopentadiene phenolic resins, salvinyl phenolic resins, novolac phenolic resins, copolymerized phenolic resins of benzaldehyde phenol and aralkyl phenol, para- and/or meta-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 foregoing. As commercially available phenolic resins, for example, Tamanol 758 manufactured by Arakawa Chemical Industries, Ltd. or HP-850N manufactured by Hitachi Chemical Co., Ltd. can be used.

Phenol novolac resins can be, for example, resins obtained by condensing or co-condensing phenols and/or naphthols with aldehydes under an acidic catalyst. The phenols comprising the phenol novolac resin can include, for example, at least one selected from the group consisting of phenol, cresol, xylenol, resorcinol, o-catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol. The naphthols comprising the phenol novolac resin can include, for example, at least one selected from the group consisting of α-naphthol, β-naphthol, and dihydroxynaphthalene. The aldehydes comprising the phenol novolac resin can include, for example, at least one selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylic aldehyde.

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, o-catechol, bisphenol A, bisphenol F, and substituted or unsubstituted diphenols.

The resin composition may contain one of the phenolic resins listed above. It may also contain multiple phenolic resins listed above. The resin composition may contain one of the curing agents listed above. It may also contain multiple curing agents listed above.

The ratio of active groups (phenolic OH groups) in the curing agent that react with the epoxy groups in the epoxy resin per equivalent of the 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. If the ratio of active groups in the curing agent is less than 0.5 equivalents, the resulting cured product may not have sufficient elastic modulus. 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 composite after curing tends to decrease. However, the effects of the present invention can be achieved even when the ratio of active groups in the curing agent is outside the above range.

The coupling agent can improve the adhesion between the resin composition and the metal-containing particles constituting the metal powder, thereby improving the flexibility and mechanical strength of the molded body formed from the composite. The resin composition of this embodiment can improve the fluidity and curing properties of the composite by containing a specific silane compound as a coupling agent. The coupling agent includes a first silane compound and a second silane compound, wherein the first silane compound has a functional group selected from an epoxy group, an amino group, a urea group, and an isocyanate group, and the second silane compound has a chain alkyl group with 6 or more carbon atoms. In this specification, a chain alkyl group with 6 or more carbon atoms is sometimes referred to as a long-chain alkyl group.

By including a first silane compound in the resin composition, a molded article having excellent high-temperature bending properties can be formed. The first silane compound has a functional group that reacts with the epoxy resin or 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.

From the perspective of further improving high-temperature bending properties, the content of the first silane compound relative to 100 parts by mass of the epoxy resin may be 0.5 parts by mass to 10 parts by mass, 1.0 parts by mass to 8.0 parts by mass, or 2.0 parts by mass to 7.0 parts by mass.

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

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

From the perspective of further improving fluidity, the content of the second silane compound may be 0.1 to 5.0 parts by mass, 0.5 to 4.0 parts by mass, or 1.0 to 3.0 parts by mass, relative to 100 parts by mass of the epoxy resin.

The coupling agent may further include a third silane compound having a butyl group. The third silane compound is a silane compound without a long-chain alkyl group. Examples of the third silane compound include 3-butylpropyltrimethoxysilane, 3-butylpropyltriethoxysilane, 3-butylpropylmethyldimethoxysilane, and 3-butylpropylmethyldiethoxysilane.

From the perspective of balancing fluidity and mechanical properties, the coupling agent content can be 1.0 to 20 parts by mass, 2.0 to 15 parts by mass, or 3.0 to 10 parts by mass, per 100 parts by mass of the epoxy resin.

The curing accelerator is not limited to any other composition, as long as it reacts with the epoxy resin to accelerate the curing of the epoxy resin. Examples of the curing accelerator include phosphorus-based curing accelerators, imidazole-based curing accelerators, and urea-based curing accelerators. The inclusion of a curing accelerator in the resin composition can improve the formability and demoldability of the composite. Furthermore, the inclusion of a curing accelerator in the resin composition can enhance the mechanical strength of molded articles (e.g., electronic components) manufactured using the composite, and improve the composite's storage stability in high-temperature/high-humidity environments.

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

As commercially available imidazole curing accelerators, 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 manufactured by Shikoku Chemicals Corporation) can be used.

Urea-based curing accelerators are not particularly limited as long as they contain urea groups. However, from the perspective of improving storage stability, alkyl urea-based curing accelerators containing alkyl urea groups are preferred. Examples of alkyl urea-based curing accelerators containing alkyl urea groups include aromatic alkyl ureas and aliphatic alkyl ureas. Commercially available alkyl urea-based curing accelerators include U-CAT3512T (trade name, manufactured by San-Apro Ltd., aromatic dimethyl urea) and U-CAT3513N (trade name, manufactured by San-Apro Ltd., aliphatic dimethyl urea). Among these, aromatic alkyl ureas are preferred because they have a relatively low decomposition temperature, allowing for efficient curing of the composite.

The amount of curing accelerator added is not particularly limited, as long as it is an amount that achieves a curing-accelerating effect. From the perspective of improving the curability and fluidity of the resin composition upon moisture absorption, the amount of curing accelerator added is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 15 parts by mass or less, and even more preferably 1.0 parts by mass or more and 10 parts by mass or less, per 100 parts by mass of the epoxy resin. When the amount of curing accelerator is 0.1 parts by mass or more, a sufficient curing-accelerating effect is easily achieved. When the amount of curing accelerator is 30 parts by mass or less, the storage stability of the composite is less likely to decrease. The curing accelerator content is preferably 0.001 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the combined epoxy resin and phenolic resin. However, the effects of the present invention can be achieved even when the curing accelerator content and amount are outside of the above ranges.

The resin composition may contain a compound with a siloxane bond (siloxane compound) as an additive. This helps reduce the shrinkage during molding of the composite and improves the heat resistance and voltage resistance of the molded article. A siloxane bond is a bond consisting of two silicon atoms (Si) and one oxygen atom (O) and can be represented by -Si-O-Si-. The compound with a siloxane bond can be a polysiloxane compound.

The content of the siloxane compound relative to 100 parts by mass of the epoxy resin 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.

To ensure environmental safety, recyclability, processability, and low cost, the composite may contain a flame retardant. For example, the flame retardant may be at least one 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 resin composition may contain one or more of these flame retardants.

When forming a molded article from the composite using a mold, the resin composition may contain wax. Wax improves the composite's fluidity during molding (e.g., transfer molding) and also acts 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.

The wax may be, for example, at least one selected from the group consisting of montanic acid, stearic acid, 12-hydroxystearic acid, acid), lauric acid and other fatty acids or their esters; zinc stearate, calcium stearate, barium stearate, aluminum stearate, magnesium stearate, calcium laurate, zinc laurate, zinc linoleate, calcium ricinoleate, zinc 2-ethylhexanoate and other fatty acid salts; stearamide, oleamide, erucamide, behenamide, palmitic acid amide, lauamide, hydroxystearamide, methylenebisstearamide, ethylenebisstearamide, ethylenebislaurate, distearyl adipamide, ethylenebisoleamide, dioleyl adipamide, N Fatty acid amides such as stearyl stearamide, N-oleyl stearamide, N-stearyl erucamide, hydroxymethyl stearamide, and hydroxymethyl behenamide; fatty acid esters such as butyl stearate; alcohols such as ethylene glycol and stearyl alcohol; polyethers including polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and their modifications; polysiloxanes such as silicone oil and silicone grease; fluorinated compounds such as fluorinated oil, fluorinated grease, and fluorinated resin powder; and waxes such as paraffin wax, polyethylene wax, amide wax, polypropylene wax, ester wax, carnauba wax, and microcrystalline wax.

From the perspective of balancing fluidity and mold release properties, the wax content per 100 parts by mass of the epoxy resin can 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.

(Metal Powder) Metal powder (particles containing metal elements) can contain, for example, at least one selected from the group consisting of metal monomers, alloys, and metal compounds. Metal element-containing powder can contain, for example, at least one selected from the group consisting of metal monomers, alloys, and metal compounds. Alloys can contain at least one selected from the group consisting of solid solutions, eutectics, and intermetallic compounds. Examples of alloys include stainless steel (Fe-Cr alloys, Fe-Ni-Cr alloys, etc.). Metal compounds can include oxides such as ferrous iron. Metal powder can contain a single metal element or multiple metal elements. The metal elements contained in the metal powder can be, for example, base metals, precious metals, transition metals, or rare earth elements. Composites can contain a single metal element-containing powder or multiple metal element-containing powders with different compositions.

The metal element contained in the metal powder can be, for example, 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), ferromagnetic element (Pr), neodymium (Nd), sulphurium (Sm), and dysentery (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 elements. The metal powder may contain, for example, carbon (C), oxygen (О), benzene (Be), phosphorus (P), sulfur (S), boron (B), or silicon (Si).

The metal powder may be a magnetic powder. The metal powder may also be a soft magnetic alloy or a ferromagnetic alloy. For example, the metal powder may be at least one magnetic powder selected from the group consisting of 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 (aluminum nickel cobalt magnets), and ferrous iron. The ferrous iron granules may be, for example, spinel ferrous iron granules, hexagonal ferrous iron granules, or garnet ferrous iron granules. 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 or more of the aforementioned elements and compositions.

The metal powder can also be Fe alone. The metal powder can also be an alloy containing iron (Fe-based alloy). Examples of Fe-based alloys include Fe-Si-Cr alloys and Nd-Fe-B alloys. The metal element-containing powder can also 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 easier to produce a molded article with a high space factor and excellent magnetic properties from the composite. The metal powder can also be an Fe amorphous alloy.

As commercially available products of Fe amorphous alloy powder, for example, at least one selected from the group consisting of AW2-08, KUAMET-6B2 (these are 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 (these are trade names manufactured by Daido Steel Co., Ltd.), MH45D, MH28D, MH25D, and MH20D (these are trade names manufactured by Kobe Steel, Ltd.) can be used.

<Compound Production Method> To produce the compound, metal powder and a resin composition (the components of the resin composition) are mixed while being heated. For example, the metal powder and resin composition are mixed while being heated using a kneader, roll, or mixer. As the metal powder and resin composition are heated and mixed, the resin composition adheres to part or all of the surface of the metal-containing particles that comprise the metal powder, coating the particles. This causes part or all of the epoxy resin in the resin composition to become semi-cured, resulting in a compound. Alternatively, a compound can 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 can also be pre-mixed.

During the mixing process, the metal powder, epoxy resin, curing agent, curing accelerator, and coupling agent can be mixed in a tank. Alternatively, the metal powder and coupling agent can be added to the tank for mixing, followed by adding the epoxy resin, curing agent, and curing accelerator to the tank and mixing the raw materials in the tank. Alternatively, the silicone compound, epoxy resin, curing agent, and coupling agent can be mixed in the tank, followed by adding the curing accelerator to the tank and mixing the raw materials in the tank. Alternatively, a mixed powder of epoxy resin, curing agent, and curing accelerator (resin mixed powder) may be prepared in advance, followed by mixing metal powder and coupling agent to prepare metal mixed powder, and then mixing the metal mixed powder with the resin mixed powder.

The mixing time also depends on the type and capacity of the mixing machine, as well as the production volume of the composite. For example, a mixing time of 1 minute or longer is preferred, 2 minutes or longer is more preferred, and 3 minutes or longer is even more preferred. Furthermore, a mixing time of 20 minutes or less is preferred, 15 minutes or less is even more preferred, and 10 minutes or less is even more preferred. A mixing time of less than 1 minute can lead to insufficient mixing, which can impair the composite's formability and cause variations in the composite's degree of cure. A mixing time exceeding 20 minutes can cause the resin component (e.g., epoxy resin or phenolic resin) to cure within the tank, which can easily impair the composite's fluidity and formability.

When the raw materials in the tank are heated and kneaded in a kneader, the heating temperature can be, for example, a temperature that produces a semi-cured epoxy resin (epoxy resin in the B stage) while suppressing the formation of a cured epoxy resin (epoxy resin in the C stage). The heating temperature can also be lower than the activation temperature of the curing accelerator. For example, 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 and easily covers the surface of the metal element-containing particles constituting the metal powder, thereby easily generating a semi-cured epoxy resin and easily inhibiting the complete curing of the epoxy resin during mixing.

[Molded Article] The molded article of this embodiment may comprise the above-described composite. The molded article of this embodiment may also comprise a cured product of the above-described composite. The molded article may comprise at least one selected from the group consisting of an uncured resin composition, a semi-cured resin composition (resin composition in the B-stage), and a cured resin composition (resin composition in the C-stage). The molded article of this embodiment can be used as a sealing material for electronic components or electronic circuit boards. This embodiment can suppress cracking in the molded article caused by differences in thermal expansion between the metal components of the electronic components or electronic circuit boards and the molded article (sealing material).

The cured composite material is a cured product of a metal powder and resin composition, with the metal powder content being 90% by mass or greater and less than 100% by mass. To enhance the strength of the cured material, the flexural strength of the cured material at 250°C is preferably 7.0 MPa or greater, more preferably 8.0 MPa or greater, and even more preferably 8.5 MPa or greater. The upper limit of the flexural strength is approximately 10 MPa. To impart flexibility to the cured material, the flexural modulus of elasticity of the cured material at 250°C can be 1.3 GPa or less, 1.2 GPa or less, or 1.1 GPa or less. The lower limit of the flexural modulus of elasticity 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 a reliability indicator for the cured product. This value is preferably 9.0× ^10⁻³ or higher, more preferably 9.2× ^10⁻³ or higher, and even more preferably 10.4× ^10⁻³ or higher. The upper limit of this value is not particularly limited, but can be, for example, 5× ^10⁻² or lower.

<Method for Producing a Molded Article> The method for producing a molded article of this embodiment may include the step of pressurizing the composite in a mold. The method for producing a molded article may include the step of pressurizing the composite covering a portion or the entire surface of a metal member in a mold. The method for producing a molded article may include only the step of pressurizing the composite in a mold or may include other steps in addition to this step. The method for producing a molded article may also include a first step, a second step, and a third step. The details of each step are described below.

In the first step, the composite is prepared using the above method.

In the second step, the composite is pressed in a mold to obtain a molded body (the molded body in stage B). In the second step, the composite can be pressed in a mold to cover a portion or the entire surface of a metal component. In the second step, the resin composition is filled between the individual metal-containing particles that make up the metal-containing powder. The resin composition acts as a binder, bonding the metal-containing particles to one another.

As a second step, transfer molding of the composite can also be implemented. In transfer molding, the composite can be pressurized at a pressure of 5 MPa to 50 MPa. The higher the molding pressure, the easier it is to obtain a molded body with excellent mechanical strength. When considering the mass production of the molded body and the life of the mold, the molding pressure is preferably 8 MPa to 20 MPa. Relative to the true density of the composite, the density of the molded body formed by transfer molding can be preferably 75% to 86%, more preferably 80% to 86%. When the density of the molded body is 75% to 86%, it is easy to obtain a molded body with excellent mechanical strength. In transfer molding, the second and third steps can also be performed together.

In the third step, the molded body is cured by heat treatment to obtain a molded body in stage C. The heat treatment temperature can be any temperature at which the resin composition in the molded body is fully cured. The heat treatment temperature is preferably from 100°C to 300°C, more preferably from 110°C to 250°C. To suppress oxidation of the metal powder in the molded body, heat treatment is preferably performed in an inert atmosphere. If the heat treatment temperature exceeds 300°C, the trace amounts of oxygen inevitably contained in the heat treatment atmosphere may oxidize the metal powder or degrade the cured resin. To prevent oxidation of the metal powder and degradation of the cured resin, and to ensure sufficient curing of the resin composition, the heat treatment temperature should be maintained for a period of at least several minutes and no more than 10 hours, more preferably at least 3 minutes and no more than 8 hours. [Example]

The present invention is further described below with reference to embodiments and comparative examples, but the present invention is not limited to these examples.

The details of the components used in the preparation of the complexes of 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 weight: 275 g/eq) Multifunctional epoxy resin (trade name: TECHMORE VG3101L, manufactured by Printec Corporation, epoxy equivalent weight: 215 g/eq)

(Curing Agent) Triphenylmethane-type phenolic resin (trade name: HE910-09, manufactured by Air Water Inc., hydroxyl equivalent weight: 101 g/eq) Biphenyl-aralkyl-type phenolic resin (trade name: MEHC-7841-4S, manufactured by Meiwa Plastic Industries, Ltd., hydroxyl equivalent weight: 166 g/eq)

(Coupling Agent) 3-Glycyrrhizic Acid (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) 3-Hydroxypropyltrimethoxysilane (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 Curing Accelerator (Shikoku Chemicals Corporation, trade name: 2P4MHZ-PW) (Release Agent) Zinc Laurate (NOF Corporation, trade name: Powder Base L) Partially Saponified Montanic Acid Wax (Clariant Chemicals Co., Ltd., trade name: Licowax-OP) (Additive) Caprolactone-modified Dimethyl Silicone (Gelest, Inc., trade name: DBL-C32)

(Metal Powder) Amorphous iron powder (Epson Atmix Corporation, trade name: 9A4-II, average particle size 24μm) Amorphous iron powder (Epson Atmix Corporation, trade name: AW2-08, average particle size 5.3μm)

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

The two types of amorphous iron powder listed in Table 1 were uniformly mixed in a pressurized double-screw kneader (Nihon Spindle Manufacturing Co., Ltd., 5L capacity) for 5 minutes to prepare metal powder. The coupling agent and additives listed in Table 1 were added to the metal powder in the double-screw kneader. The contents of the double-screw kneader were then heated to 90°C and mixed for 10 minutes while maintaining this temperature. The resin mixture was then added to the contents of the double-screw kneader and melted and kneaded for 15 minutes while maintaining the temperature at 120°C. After cooling the mixture obtained from the above melting/kneading process to room temperature, the mixture was pulverized with a hammer until the mixture had a predetermined particle size. The term "melting" herein refers to the melting of at least a portion of the resin composition within the contents of the double-screw kneader. The metal powder in the composite does not melt during the composite preparation process. The composites of Examples 1 to 5 were prepared using the above method.

(Comparative Examples 1-3) Except for varying the types and amounts of the components as shown in Table 2, the same procedures as in Example 1 were followed to prepare the complexes of Comparative Examples 1-3.

[Evaluation of the Complexes] The complexes obtained in the Examples and Comparative Examples were evaluated as follows. The results are shown in Tables 1 and 2.

(Flowability) Flowability was evaluated using a CFT-100 flow tester manufactured by Shimadzu Corporation. 7 g of the compound was molded into tablets. The tablets were subjected to flowability evaluation at 130°C, afterheating for 20 seconds, and a load of 100 kg. The plunger's displacement (unit: mm) until the compound stopped flowing was defined as the flow tester stroke. The time until the compound stopped flowing was measured as the flow time, which was used as an indicator of flowability.

(Gel Time) The gel time of the composite was measured using the following method. Using a Curemeter (manufactured by JSR Trading Co., Ltd.), the gel time was measured at 140°C using a 1.5 mL sample. The gel time was the time at which the torque onset in the resulting graph began to rise. A shorter gel time indicates a higher curability.

(Bending Test) The composite was transfer molded at a mold temperature of 140°C, a molding pressure of 13.5 MPa, and a curing time of 360 seconds. The specimens were then post-cured at 180°C for 2 hours to produce test pieces. The test piece dimensions were 80 mm in width, 10 mm in width, and 3.0 mm in thickness.

A three-point supported bending test was conducted on a specimen at 250°C using an automatic stereo plotter equipped with a constant temperature bath. The AGS-500A, manufactured by Shimadzu Corporation, was used as the automatic stereo plotter. During the bending test, one surface of the specimen was supported by two supporting points. A load was applied to the other surface of the specimen, midway between the two supporting points. The load at which the specimen broke was measured. The bending test measurement conditions are as follows. Distance between two pivot 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)

Calculate the flexural strength σ (unit: MPa) using the following formula (A). Calculate the flexural modulus E (unit: GPa) using the following formula (B). In the following formulas, "P" is the load at which the specimen breaks (unit: N). "Lv" is the distance between the two support points (unit: mm). "W" is the width of the specimen (unit: mm). "t" is the thickness of the specimen (unit: mm). "F/Y" is the slope of the straight line portion of the load-deflection curve (unit: N/mm). σ = (3 × P × Lv) / (2 × W × t ² ) (A) E = [Lv ³ / (4 × W × t ³ )] × (F/Y) (B)

(Reliability) The value obtained by dividing the flexural strength (MGa) at 250°C by the flexural modulus (GPa) at 250°C is used as a reliability evaluation index. A larger value indicates a better balance between strength and modulus.

(Reflow Treatment) A copper metal component was sealed with a composite material by transfer molding, and the composite material was solidified to produce a molded body. The molded body was then reflowed. The maximum heating temperature during the reflow treatment was 260°C, and the heating time was 300 seconds. After the reflow treatment, the molded body was inspected for cracks. "A" in the table indicates no cracks, and "B" indicates cracks.

【Table 1】 Embodiment 1 2 3 4 5 epoxy resin NC-3000 50 50 50 50 50 VG-3101L 50 50 50 50 50 curing agent HE910-09 twenty two twenty two twenty two twenty two twenty two MEHC-7841-4S 29 29 29 29 29 Curing accelerator 2P4MHZ-PW 2.0 2.0 2.0 2.0 2.0 coupling agent KBM-403 3.0 3.0 3.0 4.0 6.0 KBM-803 1.0 1.0 0.5 0.5 1.0 KBM-5803 1.5 1.5 1.5 1.5 1.5 release agent Powder Base L 6.0 5.0 5.0 5.0 5.0 Licowax-OP 2.0 2.0 2.0 2.0 2.0 additives DBL-C32 30 30 30 30 30 metal powder 9A4-II 4314 4292 4281 4303 4358 AW2-08 947 942 940 944 957 Metal powder content (mass %) 96.4 96.4 96.4 96.4 96.4 Flow tester @130℃ Stroke length (mm) 10.6 10.6 10.7 10.7 9.7 Flow time (seconds) 17 18 18 19 17 Gelling time@140℃(seconds) 250 240 245 245 230 250℃ flexural modulus (GPa) 1.0 0.8 0.9 0.9 1.0 250℃ flexural strength (MPa) 9.4 8.6 8.5 9.2 9.7 Reliability index (×10 ^-3 ) 9.9 10.3 9.6 10.2 9.4 Return Evaluation A A A A A

【Table 2】 Comparative example 1 2 3 epoxy resin NC-3000 50 50 50 VG-3101L 50 50 50 curing agent HE910-09 twenty two twenty two twenty two MEHC-7841-4S 29 29 29 Curing accelerator 2P4MHZ-PW 2.0 2.0 2.0 coupling agent KBM-403 - 3.0 - KBM-803 - 2.0 3.0 KBM-5803 1.5 - 1.5 release agent Powder Base L 6.0 5.0 5.0 Licowax-OP 2.0 2.0 2.0 additives DBL-C32 30 30 30 metal powder 9A4-II 4226 4281 4270 AW2-08 928 940 937 Metal powder content (mass %) 96.4 96.4 96.4 Flow tester @130℃ Stroke length (mm) 10.7 7.5 9.0 Flow time (seconds) 13 31 30 Gelling time@140℃(seconds) 250 210 220 250℃ flexural modulus (GPa) 0.7 1.1 0.8 250℃ flexural strength (MPa) 6.5 10.6 8.7 Reliability index (×10 ^-3 ) 9.0 9.3 10.3 Return Evaluation B A A

Claims (7)

A composite material comprising metal powder and a resin composition containing an epoxy resin, a curing agent, and a coupling agent. The coupling agent comprises a first silane compound, a second silane compound, and a third silane compound having an alkyl group. The first silane compound has a functional group selected from an epoxy group, an amine group, a urea group, or an isocyanate group. The second silane compound has a carbon chain hydrocarbon group having 6 or more carbon atoms and a styryl group, a (meth)acryl group, or a vinyl group. The content of the metal powder is 90% by mass or more and less than 100% by mass. The complex as described in claim 1, wherein the first silane compound has an epoxy group. The composite of claim 1 or claim 2, wherein the coupling agent is present in an amount of not less than 1.0 part by mass and not more than 20 parts by mass relative to 100 parts by mass of the epoxy resin. The composite material of claim 1 or claim 2, wherein the metal powder comprises at least one metal element selected from the group consisting of iron, cobalt, and nickel. The composite material as described in claim 1 or claim 2, wherein the metal powder is magnetic powder. A shaped body comprising the composite according to any one of claims 1 to 5. A cured product, which is a cured product of the composite according to any one of claims 1 to 5.