JP7480565B2 - Compound, molded body, and cured product of 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, sealing materials, electromagnetic shields (EMI shields), bonded magnets, etc. (see Patent Document 1 below).

JP 2014-13803 A

When manufacturing industrial products from a compound, the compound is supplied and filled into a mold through a flow path, or parts such as coils are embedded in the compound in the mold. However, when the metal powder content in the compound is 96% by mass or more, the fluidity of the compound is significantly reduced, making it difficult for the compound to be filled into a mold, and the strength of the molded body formed from the compound is likely to decrease. Therefore, there is a demand to improve the mechanical strength of the molded body.

The present invention aims to provide a compound capable of forming a molded body having excellent mechanical strength, a molded body using the compound, and a cured product of the compound.

The compound according to one aspect of the present invention comprises a metal powder and a resin composition, the metal powder content being 96% by mass or more and less than 100% by mass, and the resin composition containing an epoxy resin, a curing agent, a wax, and a coupling agent having a mercapto group.

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

The present invention provides a compound capable of forming a molded body having excellent mechanical strength, a molded body using the compound, and a cured product of the compound.

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

[compound]
The compound according to the present embodiment includes a metal powder and a resin composition. The metal powder may contain at least one selected from the group consisting of, for example, a metal element, an alloy, an amorphous powder, and a metal compound. The resin composition contains at least an epoxy resin, a curing agent, a wax, and a coupling agent having a mercapto group. In the compound, the metal powder, the epoxy resin, the curing agent, the wax, and the coupling agent are mixed. The resin composition may further contain a curing accelerator, an additive, and the like as other components. The resin composition may be a component that may include an epoxy resin, a curing agent, a curing accelerator, a wax, a coupling agent, and an additive, and may be the remaining component (non-volatile component) excluding the organic solvent and the metal powder. The additive is the remaining component of the resin composition excluding the resin, the wax, the coupling agent, the curing agent, and the curing accelerator. The additive is, for example, a flame retardant, a lubricant, and the like. The compound may be a powder (compound powder).

The compound may comprise a metal powder and a resin composition attached 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 product of the 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 product of the resin composition. The compound may be composed of a metal powder and a resin composition.

The content of metal powder in the compound is 96% by mass or more and less than 100% by mass. As the content of metal powder increases, the filling rate of the metal powder in the compound increases, and the relative permeability of the compound increases. Compounds with high relative permeability are suitable, for example, as sealing materials for inductors or raw materials for inductor cores. However, if the content of metal powder in a compound that does not contain wax is 96% by mass or more, the fluidity of the compound is significantly reduced. The content of metal powder in the compound may preferably be 96% by mass or more and 99.8% by mass or less, 96% by mass or more and 99% by mass or less, 96% by mass or more and 98% by mass or less, or 96.1% by mass or more and 97.5% by mass or less.

The average particle size of the metal powder is not particularly limited, but may be, for example, 1 μm or more and 300 μm or less. The average particle size may be measured, for example, by a particle size distribution analyzer. The shape of the individual metal particles constituting the metal powder is not limited, but may be, for example, spherical, flat, prismatic, or acicular. The compound may contain multiple types of metal powder with different average particle sizes.

Depending on the composition or combination of the metal powders contained in the compound, the various properties such as the electromagnetic properties of the molded body formed from the compound can be freely controlled, and the molded body can be used as various industrial products or their raw materials. Examples of industrial products manufactured using the compound include automobiles, medical equipment, electronic devices, electrical equipment, information and communication devices, home appliances, audio equipment, and general industrial equipment. When the compound contains a permanent magnet such as an Sm-Fe-N alloy or an Nd-Fe-B alloy as the metal powder, the compound may be used as a raw material for bonded magnets. When the compound contains a soft magnetic powder such as an Fe-Si-Cr alloy or ferrite as the metal powder, the compound may be used as a raw material for inductors (e.g., EMI filters) or transformers (e.g., magnetic cores). When the compound contains iron and copper as the metal powder, the molded body (e.g., a sheet) formed from the compound may be used as an electromagnetic wave shield.

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

The resin composition according to the present embodiment contains an epoxy resin as a thermosetting resin, which can improve the fluidity of the compound. The epoxy resin may be, for example, a resin having two or more epoxy groups in one molecule. The type of epoxy resin is not particularly limited and can be selected according to the desired properties of the composition. The resin composition may contain multiple types of epoxy resins.

Epoxy resins include, for example, biphenyl type epoxy resins, stilbene type epoxy resins, diphenylmethane type epoxy resins, sulfur atom-containing epoxy resins, novolac type epoxy resins, dicyclopentadiene type epoxy resins, salicylaldehyde type epoxy resins, naphthol and phenol copolymer type epoxy resins, epoxidized products of 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 glycidyl ether type epoxy resins of terpene modified phenolic resins. The epoxy resin may contain at least one selected from the group consisting of epoxy resins, cyclopentadiene type epoxy resins, glycidyl ether type epoxy resins of polycyclic aromatic ring modified phenolic resins, glycidyl ether type epoxy resins of naphthalene ring-containing phenolic resins, glycidyl ester type epoxy resins, glycidyl or methylglycidyl type epoxy resins, alicyclic type epoxy resins, halogenated phenol novolac type epoxy resins, orthocresol novolac type epoxy resins, trisphenol methane 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, trisphenolmethane type epoxy resins, orthocresol novolac type epoxy resins, phenol novolac type epoxy resins, bisphenol type epoxy resins, epoxy resins having a bisphenol skeleton, salicylaldehyde novolac type epoxy resins, and naphthol novolac type epoxy resins.

From the viewpoint of further increasing the mechanical strength of the molded body, the epoxy resin may contain at least one selected from the group consisting of trisphenolmethane type epoxy resins and orthocresol novolac type epoxy resins.

The epoxy resin may be a crystalline epoxy resin. Although the molecular weight of the crystalline epoxy resin is relatively low, the crystalline epoxy resin has a relatively high melting point and excellent flowability. The crystalline epoxy resin (highly crystalline epoxy resin) may contain at least one selected from the group consisting of hydroquinone type epoxy resin, bisphenol type epoxy resin, thioether type epoxy resin, and biphenyl type epoxy resin. 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, 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 of which are product 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-502 H, 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).

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, phenol novolac resins, and dicyandiamide (DICY). There are no particular restrictions on the type of curing agent, and it can be selected according to the desired properties of the resin composition.

When a curing agent that cures epoxy resins in the range of low 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 compound also tends to be soft. On the other hand, from the viewpoint of improving the heat resistance of the molded body, the curing agent may preferably be a heat-curing type curing agent, more preferably a phenolic resin, and even more preferably a phenolic novolac resin. In particular, by using a phenolic 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 at least one selected from the group consisting of aralkyl-type phenolic resin, dicyclopentadiene-type phenolic resin, salicylaldehyde-type phenolic resin, novolac-type phenolic resin, copolymerized phenolic resin of benzaldehyde-type phenol and aralkyl-type phenol, paraxylylene- and/or metaxylylene-modified phenolic resin, melamine-modified phenolic resin, terpene-modified phenolic resin, dicyclopentadiene-type naphthol resin, cyclopentadiene-modified phenolic resin, polycyclic aromatic ring-modified phenolic resin, biphenyl-type phenolic resin, and triphenylmethane-type phenolic resin. The phenolic resin may be a copolymer composed of two or more of the above. As a commercially available phenolic resin, for example, Tamanol 758 manufactured by Arakawa Chemical Industries Co., Ltd. or HP-850N manufactured by Hitachi Chemical Co., Ltd. may be used.

The phenol novolac resin may be, for example, a resin obtained by condensing or co-condensing phenols and/or naphthols with aldehydes under an acid catalyst. The phenols constituting the phenol novolac resin may include, for example, at least one selected from the group consisting of phenol, cresol, xylenol, resorcin, 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 in one molecule. The compound having two phenolic hydroxyl groups in one molecule may include, for example, at least one selected from the group consisting of resorcinol, catechol, bisphenol A, bisphenol F, and substituted or unsubstituted biphenol.

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 resin composition may contain one type of phenolic resin from among the above. The resin composition may comprise multiple types of phenolic resins 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 may be preferably 0.5 to 1.5 equivalents, more preferably 0.6 to 1.4 equivalents, and even more preferably 0.7 to 1.2 equivalents per equivalent of epoxy groups in the epoxy resin. If the ratio of active groups in the curing agent is less than 0.5 equivalents, it is difficult to obtain a sufficient elastic modulus of the resulting cured product. On the other hand, if the ratio of active groups in the curing agent exceeds 1.5 equivalents, the mechanical strength of the molded product formed from the compound after curing tends to decrease. However, even if the ratio of active groups in the curing agent is outside the above range, the effects of the present invention can be obtained.

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 contain a fatty acid, a metal salt of a fatty acid, or an ester of a fatty acid. The fatty acid ester may be saponified.

Waxes include, for example, fatty acids such as montanic acid, stearic acid, 12-oxystearic acid, and lauric acid, or esters thereof; fatty acid salts such as calcium montanate, zinc stearate, calcium stearate, barium stearate, aluminum stearate, magnesium stearate, calcium laurate, zinc linoleate, calcium ricinoleate, and zinc 2-ethylhexanoate; 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 adipate amide, ethylene bisoleic acid amide, dioleyl adipate amide, and N-stearyl stearin. may contain at least one selected from the group consisting of fatty acid amides such as N-oleyl stearic acid amide, N-stearyl erucic acid amide, methylol stearic acid amide, and methylol behenic acid amide; fatty acid esters such as butyl stearate; alcohols such as ethylene glycol and stearyl alcohol; polyether compounds consisting of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and modified products thereof; polysiloxane compounds 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 improve the fluidity and filling properties of the compound, the wax may contain a partially saponified montanic acid ester. The partially saponified montanic acid ester may be a mixture of a montanic acid ester and a metal salt of montanic acid. The metal salt of montanic acid may be calcium montanate.

The wax content in the compound may be 0.5 parts by mass or more and 20 parts by mass or less, 1 part by mass or more and 18 parts by mass or less, or 2 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the epoxy resin. By having the wax content within the above range, the fluidity and filling properties of the compound are easily improved, and the mechanical strength of the molded body formed from the compound is easily improved.

The coupling agent having a mercapto group improves the adhesion between the resin composition and the metal element-containing particles that make up the metal powder, and improves the mechanical strength of the molded body formed from the compound. The coupling agent may be, for example, a silane compound (silane coupling agent) having a mercapto group. Examples of silane coupling agents having a mercapto group include 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and silicone alkoxy oligomers having a mercapto group.

From the viewpoint of further increasing the mechanical strength of the molded body, the content of the coupling agent having a mercapto group may be 0.01 parts by mass or more and 6 parts by mass or less, 0.1 parts by mass or more and 5 parts by mass or less, 0.3 parts by mass or more and 4 parts by mass or less, or 0.5 parts by mass or more and 3 parts by mass or less, relative to 100 parts by mass of the epoxy resin.

The resin composition may further contain a curing accelerator. The curing accelerator is not limited to any particular composition, so long as it reacts with the epoxy resin to promote 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 containing a curing accelerator in the resin composition, the moldability and releasability of the compound can be improved. In addition, by containing a curing accelerator in the resin composition, the mechanical strength of a molded body (e.g., an electronic component) produced using the compound is improved, and the storage stability of the compound in a high-temperature and high-humidity environment is improved.

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

As a commercially available imidazole curing accelerator, 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 of which are product names manufactured by Shikoku Chemical Industry Co., Ltd.) may be used.

The urea-based curing accelerator is not particularly limited as long as it is a curing accelerator having a urea group, but from the viewpoint of improving storage stability, an alkylurea-based curing accelerator having an alkylurea group is preferable. Examples of alkylurea-based curing accelerators having an alkylurea group include aromatic alkylureas and aliphatic alkylureas. Examples of commercially available alkylurea-based curing accelerators include U-CAT3512T (aromatic dimethylurea) and U-CAT3513N (aliphatic dimethylurea) manufactured by San-Apro Co., Ltd. Among these, aromatic alkylureas are preferable because they have a moderately low cleavage temperature and are easy to efficiently cure the compound.

The amount of the curing accelerator to be used is not particularly limited as long as it is an amount that can achieve a curing acceleration effect. From the viewpoint of improving the curing property and flowability of the resin composition when it absorbs moisture, the content of the curing accelerator may be 0.1 parts by mass or more and 30 parts by mass or less, 1 part by mass or more and 15 parts by mass or less, or 1 part by mass or more and 10 parts by mass or less, per 100 parts by mass of the epoxy resin.

For the purpose of the environmental safety, recyclability, moldability, and low cost of the compound, the compound may contain a flame retardant. 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 of the above flame retardants, or may contain multiple of the above flame retardants.

(Metal powder)
The metal powder (metal element-containing particle) may contain at least one selected from the group consisting of, for example, a metal element, an alloy, and a metal compound. The metal powder may be, for example, at least one selected from the group consisting of a metal element, an alloy, and a metal compound. The alloy may contain 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 type of metal element or multiple types of metal elements. The metal element contained in the metal powder may be, for example, a base metal element, a precious metal element, a transition metal element, or a rare earth element. The compound may contain one type of metal element-containing powder, or may contain multiple types of metal element-containing powders with different compositions.

The metal powder is not limited to the above composition. The metal element contained in the metal powder may be at least one selected from the group consisting of iron (Fe), copper (Cu), titanium (Ti), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), tin (Sn), chromium (Cr), niobium (Nb), barium (Ba), strontium (Sr), lead (Pb), silver (Ag), praseodymium (Pr), neodymium (Nd), samarium (Sm), and dysprosium (Dy). The metal powder may further contain elements other than 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 a 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 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 (Alnico magnets) and ferrite. The ferrite may be, for example, spinel ferrite, hexagonal ferrite, or 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 multiple 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-based alloy or an Nd-Fe-B-based alloy. The metal element-containing powder may be at least one of an amorphous iron powder and a 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 having a high space factor and excellent magnetic properties from the compound. The metal powder may be an Fe amorphous alloy.

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

<Compound manufacturing method>
In the manufacture of 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 with a kneader, roll, stirrer, etc. while being heated. By heating and mixing the metal powder and the resin composition, the resin composition adheres to a part or the whole of the surface of the metal element-containing particles constituting the metal powder to cover the metal element-containing particles, and a part or the whole of the epoxy resin in the resin composition becomes a semi-cured product. As a result, a compound is obtained. The compound may 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 the wax may be mixed in advance.

In the kneading, the metal powder, epoxy resin, hardener, hardening accelerator, wax, and coupling agent may be kneaded in a tank. After the metal powder and coupling agent are charged into the tank and mixed, the wax, epoxy resin, hardener, and hardening accelerator may be charged into the tank and the raw materials in the tank may be kneaded. After the epoxy resin, hardener, and coupling agent are kneaded in the tank, the hardening accelerator may be charged into the tank and the raw materials in the tank may be further kneaded. A mixed powder (resin mixed powder) of wax, epoxy resin, hardener, and hardening accelerator may be prepared in advance. The metal powder and coupling agent may be kneaded in advance to prepare the metal mixed powder. The metal mixed powder and resin mixed powder may be kneaded to obtain a compound.

The kneading time depends on the type of kneading machine, the volume of the kneading machine, and the amount of compound produced, but is preferably 1 minute or more, more preferably 2 minutes or more, and even more preferably 3 minutes or more. The kneading time is preferably 20 minutes or less, more preferably 15 minutes or less, and even more preferably 10 minutes or less. If the kneading time is less than 1 minute, the kneading is insufficient, the moldability of the compound is impaired, and the degree of hardening of the compound varies. If the kneading time exceeds 20 minutes, for example, the hardening of the resin composition (e.g., epoxy resin and phenolic resin) progresses in the tank, and the fluidity and moldability of the compound are easily impaired. When the raw materials in the tank are kneaded with a kneader while being heated, the heating temperature may be, for example, a temperature at which a semi-cured product of the epoxy resin (epoxy resin in B stage) is generated and the generation of a hardened product of the epoxy resin (epoxy resin in C stage) is suppressed. The heating temperature may be a temperature lower than the activation temperature of the hardening 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, a semi-cured epoxy resin is easily produced, and complete curing of the epoxy resin during kneading is easily suppressed.

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

The cured product of the compound is a cured product of metal powder and a resin composition, and the content of metal powder is 96% by mass or more and less than 100% by mass. From the viewpoint of increasing the mechanical strength of the cured product, the bending strength of the cured product at 140°C may be 24 MPa or more, 26 MPa or more, or 28 MPa or more. Since a higher bending strength is preferable, the upper limit is not particularly limited, and for example, the bending strength at 140°C may be 100 MPa or less, 80 MPa or less, or 50 MPa or less.

<Method of manufacturing molded body>
The method for producing a molded body according to this embodiment may include a step of pressurizing the compound in a mold. The method for producing a molded body may include a step of pressurizing the compound covering a part or the entire surface of the metal member in a mold. The method for producing a molded body may include only the step of pressurizing the 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 covering a part or the entire surface of the metal member may be pressed in a mold to obtain a molded body (B-stage molded body). In the second step, the 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.

As the second step, transfer molding of the compound may be performed. In the 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 body with excellent mechanical strength. When considering the mass productivity of the molded body 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 body formed by transfer molding may be preferably 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 body is 75% or more and 86% or less, a molded body with excellent mechanical strength is easily obtained. In the transfer molding, the second step and the third step may be performed together.

In the third step, the molded body is cured by heat treatment to obtain a molded body in the C stage. The heat treatment temperature may be any temperature at which the resin composition in the molded body is sufficiently cured. The heat treatment temperature may be preferably 100°C or more and 300°C or less, more preferably 110°C or more and 250°C or less. In order to suppress oxidation of the metal powder in the molded body, it is preferable to perform the heat treatment in an inert atmosphere. If the heat treatment temperature exceeds 300°C, the metal powder may be oxidized or the resin cured product may deteriorate due to the trace amount of oxygen inevitably contained in the heat treatment atmosphere. In order to sufficiently cure the resin composition while suppressing oxidation of the metal powder and deterioration of the resin cured product, the heat treatment temperature may be held for a period of preferably several minutes to 10 hours, more preferably 3 minutes to 8 hours.

The present invention will be described in more detail below with reference to 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 given below.

(Epoxy resin)
Orthocresol novolac epoxy resin (DIC Corporation product name: Epicron N500P-10, epoxy equivalent: 200 g/eq)
Trisphenolmethane type epoxy resin (product name: EPPN-501HY, Nippon Kayaku Co., Ltd., epoxy equivalent: 169 g/eq)
(Hardening agent)
Novolac phenolic resin (product name: HP-850N, manufactured by Hitachi Chemical Co., Ltd., hydroxyl group equivalent: 106 g/eq)
(Cure Accelerator)
Urea-based curing accelerator (product name: U-CAT 3512T, manufactured by San-Apro Co., Ltd.)
(Coupling Agent)
3-Mercaptopropyltrimethoxysilane (trade name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.)
3-Glycidoxypropyltrimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)
(wax)
Partially saponified Montan acid ester wax (product name: LICOWAX-OP, manufactured by Clariant Chemicals Co., Ltd.)
(Metal powder)
Amorphous iron powder (product name: 9A4-II, manufactured by Epson Atmix Corporation, average particle size: 24 μm)
FeSiCr alloy powder (manufactured by Shinto Kogyo Co., Ltd., average particle size: 2.1 μm)

[Preparation of Compound]
The epoxy resin, curing agent, curing accelerator, and wax shown in Table 1 were charged into a plastic container in the amounts (unit: g) shown in the same 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.

The two types of metal powders shown in Table 1 were mixed uniformly for 5 minutes in a pressurized twin-axis kneader (manufactured by Nippon Spindle Manufacturing Co., Ltd., capacity 5 L) to prepare metal powder. The coupling agent shown in Table 1 was added to the metal powder in the twin-axis kneader. Next, the contents of the twin-axis kneader were heated to 90°C, and the contents of the twin-axis kneader were mixed for 10 minutes while maintaining that temperature. Next, the above resin mixture was added to the contents of the twin-axis kneader, and the contents were melted and kneaded for 15 minutes while maintaining the temperature of the contents at 120°C. The kneaded product obtained by the above melting and kneading was cooled to room temperature, and then crushed with a hammer until the kneaded product had a predetermined particle size. Note that the above "melting" means melting at least a part of the resin composition in the contents of the twin-axis kneader. The metal powder in the compound does not melt during the preparation process of the compound. The compounds of the examples and comparative examples were prepared by the above method.

(Bending test)
The compound was transfer molded under the 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. The dimensions of the test specimen were 80 mm long x 10 mm wide x 3.0 mm thick.

A three-point support bending test was carried out on the test specimen at 25°C and 140°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 center position between the two supports on the other side of the test specimen. 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). In the formula, "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).
σ=(3×P×Lv)/(2×W× ^t2 ) (A)

Claims (5)

The present invention comprises a metal powder and a resin composition,
The content of the metal powder is 96% by mass or more and less than 100% by mass,
The resin composition contains an epoxy resin, a curing agent, a wax, and a coupling agent having a mercapto group ,
the wax contains a partially saponified Montan acid ester, and the content of the wax is 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the epoxy resin;
The compound , wherein the content of the coupling agent is 0.01 parts by mass or more and 6 parts by mass or less per 100 parts by mass of the epoxy resin . The compound of claim 1 , wherein the coupling agent comprises a silane compound having a mercapto group. The compound according to claim 1 or 2 , wherein the resin composition further comprises a curing accelerator . A molded article comprising the compound according to any one of claims 1 to 3 . A cured product of the compound according to any one of claims 1 to 3 .