Epoxy resin composition, cured product and electrical / electronic component

Abstract

To provide an epoxy resin composition excellent in moldability and relative permeability while being excellent in productivity.SOLUTION: There is provided an epoxy resin composition comprising an epoxy resin (A), a curing agent (B) and a magnetic filler (C) having a circularity of 0.9 or less, wherein the content of the magnetic filler (C) is more than 85 mass% relative to the epoxy resin composition, the viscosity measured at 23°C and 5 rpm is 1000 Pa s or less and the relative permeability of the cured product at a frequency of 100 MHz is 14 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin composition, a cured product, and an electric / electronic part. [Background technology]

[0002] Highly loaded magnetic filler pastes are used for through-hole filling and in the fabrication of inductor components. In the fabrication of inductor components, the higher the relative magnetic permeability, the better from the perspective of improving electrical circuit efficiency. Therefore, increasing the loading of magnetic filler is a common practice to increase the relative magnetic permeability, thereby improving the power supply efficiency of the device. Furthermore, since the higher the loading of magnetic filler, the higher the viscosity of the composition. Therefore, in through-hole filling applications, measures such as dilution with a solvent have been used to ensure moldability.

[0003] However, when diluted with a solvent, the solvent volatilizes during curing, which can cause voids and lead to poor physical properties. Therefore, although the relative permeability increases as the amount of magnetic filler added increases, the viscosity of the resin composition also increases, resulting in poor moldability. Therefore, it is known to use magnetic fillers with a high degree of circularity to ensure moldability, but when magnetic fillers with a high degree of circularity are used, it becomes difficult for the fillers to form paths between each other, which causes the problem of deteriorating electromagnetic properties such as relative permeability.In other words, pursuing relative permeability creates a trade-off between relative permeability and viscosity, in which moldability is no longer ensured.

[0004] To address this problem, Patent Document 1 discloses that by preparing and using magnetic powder having a predetermined particle size distribution, even when filled with magnetic filler having a high degree of circularity, a magnetic paste having moldability and a relatively high relative magnetic permeability can be obtained. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2020 / 075745 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the magnetic paste of Patent Document 1 requires the preparation of magnetic powder having a predetermined particle size distribution, and therefore there is room for improvement in productivity.

[0007] Under these circumstances, an object of the present invention is to provide an epoxy resin composition that is excellent in productivity, moldability, and relative magnetic permeability. [Means for solving the problem]

[0008] However, in view of the above circumstances, the present inventors have conducted extensive research and have found that by incorporating a large amount of magnetic filler with a low circularity, an epoxy resin composition can be obtained which is excellent in productivity, moldability and relative magnetic permeability, and have thus completed the present invention.

[0009] That is, the present invention has the following aspects. [1] An epoxy resin composition containing an epoxy resin (A), a curing agent (B), and a magnetic filler (C) having a circularity of 0.9 or less, the content of the magnetic filler (C) is more than 85% by mass relative to the epoxy resin composition, The epoxy resin composition has a viscosity of 1000 Pa s or less when measured at 23°C and 5 rpm, and a cured product of the epoxy resin composition has a relative magnetic permeability of 14 or more at a frequency of 100 MHz. [2] The epoxy resin composition according to [1], further comprising a dispersant having a terminal phosphate group. [3] The epoxy resin composition according to [1] or [2], wherein the glass transition temperature of the epoxy resin composition is 100°C or higher. [4] The epoxy resin composition according to any one of [1] to [4], wherein the epoxy resin composition does not contain a solvent. [5] A cured product comprising the epoxy resin composition according to any one of [1] to [4]. [6] An electrical or electronic part comprising the cured product according to [5]. [Effects of the Invention]

[0010] The epoxy resin composition of the present invention is excellent in productivity, moldability and relative magnetic permeability. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described below based on examples of embodiments for carrying out the present invention, but the present invention is not limited to the embodiments described below.

[0012] In this specification, "x and / or y (x and y are optional configurations)" means at least one of x and y, and can mean three possibilities: x only, y only, or x and y. In this specification, when the expression "X to Y" (X and Y are any numbers) is used, unless otherwise specified, it means "X or more and Y or less," as well as "preferably larger than X" or "preferably smaller than Y." In this specification, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also means that "it is preferably greater than X" or "it is preferably less than Y." In the present specification, when numerical ranges are described in stages, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In addition, in the numerical ranges described in this specification, the upper or lower limit of the numerical range can also be replaced with the values ​​shown in the examples.

[0013] An epoxy resin composition according to one embodiment of the present invention (hereinafter, sometimes referred to as "the present epoxy resin composition") contains an epoxy resin (A), a curing agent (B), and a magnetic filler (C). Each component will be described below.

[0014] <Epoxy resin (A)> The epoxy resin (A) used in the present epoxy resin composition preferably contains an epoxy resin (A1) having an aliphatic structural unit, from the viewpoint of reducing the viscosity of the composition and improving moldability. Furthermore, since epoxy resins (A1) having aliphatic structural units tend to have low glass transition temperatures, it is preferable to use an epoxy resin (A2) having a relatively high glass transition temperature in addition to the epoxy resin (A1). In other words, by using the epoxy resin (A1) and the epoxy resin (A2) in combination, it is possible to increase the glass transition temperature while reducing the viscosity.

[0015] The epoxy resin (A1) is not particularly limited as long as it is an epoxy resin having an aliphatic structural unit and no aromatic ring. Examples thereof include monoepoxy compounds such as monoglycidyl ether compounds of aliphatic alcohols and glycidyl esters of alkylcarboxylic acids; polyglycidyl ether compounds of aliphatic polyhydric alcohols or their alkylene oxide adducts; polyfunctional epoxy compounds such as polyglycidyl esters of aliphatic long-chain polybasic acids; epoxy resins having an alicyclic structure; and alicyclic epoxy resins having an ester skeleton.

[0016] Specific examples of the epoxy resin (A1) include alkyl glycidyl ethers such as allyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, and C11-13 mixed alkyl glycidyl ether (a mixture of alkyl glycidyl ethers in which the alkyl group has 11 to 13 carbon atoms); diglycidyl ethers of dihydric alcohols such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and propylene glycol diglycidyl ether; triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, and tripropylene glycol diglycidyl ether. Examples of suitable glycidyl ethers include glycidyl ethers of polyhydric alcohols such as glycidyl ether, tetraglycidyl ether of sorbitol, hexaglycidyl ether of dipentaerythritol, diglycidyl ether of polyethylene glycol, diglycidyl ether of polypropylene glycol, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerin polyglycidyl ether; polyglycidyl ether compounds of polyether polyols obtained by adding one or more alkylene oxides to aliphatic polyhydric alcohols such as propylene glycol, trimethylolpropane, and glycerin; and diglycidyl esters of aliphatic long-chain dibasic acids. Further examples include monoglycidyl ethers of aliphatic higher alcohols, glycidyl ester compounds of higher fatty acids, epoxidized soybean oil, octyl epoxy stearate, butyl epoxy stearate, and epoxidized polybutadiene.

[0017] Among these, from the viewpoint of reducing the viscosity of the composition and improving the handleability, glycidyl ether compounds of aliphatic alcohols, or polyglycidyl ether compounds of aliphatic polyhydric alcohols or their alkylene oxide adducts are preferred. The epoxy resin (A1) having an aliphatic structural unit may be an epoxy resin having a monofunctional aliphatic structural unit, or an epoxy resin having a difunctional or higher aliphatic structural unit.

[0018] The epoxy resin (A1) preferably has an epoxy equivalent of 50 g / equivalent or more and 500 g / equivalent or less, and more preferably 80 g / equivalent or more and 200 g / equivalent or less. When the epoxy equivalent is equal to or greater than the lower limit, the heat resistance of the composition is good, and when the composition is used in an electronic device, reliability such as long-term hydrolysis resistance is good. On the other hand, when the epoxy equivalent is equal to or less than the upper limit, the viscosity of the composition tends to be low, and handling is good. The epoxy resin (A1) may be one of the compounds exemplified above, or two or more of them may be mixed in any combination and ratio, and the epoxy equivalent in the case of a mixture is the equivalent of the mixture.

[0019] The epoxy resin (A2) in the present embodiment is an epoxy resin other than the epoxy resin (A1), and is preferably an epoxy resin having an aromatic structural unit, from the viewpoints of increasing the glass transition temperature of the composition and improving reliability such as long-term heat resistance when the composition is used in an electronic device.

[0020] Examples of the epoxy resin (A2) include those having, as structural units, benzene rings; condensed aromatic ring structures such as naphthalene rings, anthracene rings, and pyrene rings; structures containing multiple aromatic ring structures such as biphenol rings, cardo structures, and fluorene rings; and heterocyclic structures such as pyrrole rings and thiophene rings. More specifically, examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, biphenyl type epoxy resins, naphthalene ring-containing epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, triphenylmethane type epoxy resins, aminophenol type epoxy resins, anthracene type epoxy resins, dihydroanthracene type epoxy resins, tetraphenylethane type epoxy resins, and bisphenol AF type epoxy resins. The epoxy resin (A2) is preferably an epoxy resin having a bifunctional or higher aromatic structural unit.

[0021] The epoxy resin (A2) preferably has an epoxy equivalent of 50 g / equivalent or more and 500 g / equivalent or less, and more preferably 80 g / equivalent or more and 250 g / equivalent or less. When the epoxy equivalent is equal to or greater than the lower limit, the heat resistance of the composition is good, and the reliability of the composition when used in an electronic device is good. On the other hand, when the epoxy equivalent is equal to or less than the upper limit, the viscosity of the composition tends to be low, and the handleability is good. The epoxy resin (A2) may be a single compound selected from the compounds exemplified above, or a mixture of two or more compounds in any combination and ratio. In the case of a mixture, the epoxy equivalent is the equivalent of the mixture.

[0022] The content of the epoxy resin (A) in the composition of the present embodiment is preferably from 1 to 20% by mass, more preferably from 2 to 15% by mass, and even more preferably from 5 to 10% by mass. When the content of the epoxy resin (A) is equal to or greater than the lower limit, the viscosity of the composition tends to be low, resulting in good handleability. On the other hand, when the content of the epoxy resin (A) is equal to or less than the upper limit, the content of the magnetic filler (C) can be relatively increased, resulting in a low coefficient of thermal expansion.

[0023] When the epoxy resins (A1) and (A2) are used in combination as the epoxy resin (A), the mass ratio (A2) / (A1) is preferably 1 or more and 4 or less, more preferably 1.5 or more and 3.5 or less, and even more preferably 2 or more and 3 or less. When the mass ratio (A2) / (A1) is equal to or greater than the lower limit, the glass transition temperature of the composition is high and the heat resistance is good. Therefore, the reliability of the composition when used in an electronic device is good. On the other hand, when the mass ratio (A2) / (A1) is equal to or less than the upper limit, the viscosity of the composition tends to be low, resulting in good handleability.

[0024] The content of the epoxy resin (A1) relative to the epoxy resin (A) in the composition of the present embodiment is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less. When the content of the epoxy resin (A1) is equal to or greater than the lower limit, the viscosity of the composition tends to be low, resulting in good handleability. On the other hand, when the content of the epoxy resin (A1) is equal to or less than the upper limit, the heat resistance of the composition is good, resulting in good reliability when the composition is used in an electronic device.

[0025] The content of the epoxy resin (A2) relative to the epoxy resin (A) in the composition of the present embodiment is preferably from 0.5 to 20% by mass, more preferably from 1 to 15% by mass, and even more preferably from 2 to 10% by mass. When the content of the epoxy resin (A2) is equal to or greater than the lower limit, the heat resistance of the composition is good, and the reliability of the composition when used in an electronic device is good. On the other hand, when the content of the epoxy resin (A2) is equal to or less than the upper limit, the viscosity of the composition is unlikely to increase, and therefore the handleability is good.

[0026] <Curing agent (B)> The curing agent (B) in the present epoxy resin composition refers to a component that contributes to the crosslinking reaction between crosslinking groups of the epoxy resin, and those generally known as epoxy resin curing agents can be used. Examples of such curing agents include phenol-based curing agents, amine-based curing agents such as aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, acid anhydride-based curing agents, amide-based curing agents, tertiary amines, imidazole and its derivatives, organic phosphines, phosphonium salts, tetraphenylboron salts, organic acid dihydrazides, boron halide amine complexes, polymercaptan-based curing agents, isocyanate-based curing agents, blocked isocyanate-based curing agents, and dicyandiamine compounds.

[0027] Specific examples of the phenol-based curing agent include bisphenol A, bisphenol F, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenyl ether, 1,4-bis(4-hydroxyphenoxy)benzene, 1,3-bis(4-hydroxyphenoxy)benzene, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, phenol novolac, bisphenol A novolac, o-cresol novolac, m-cresol novolac, p-cresol novolac, xylenol novolac, poly-p-hydroxystyrene, hydroquinone, resorcinol, catechol, and t-butyl catechol. ethanol, t-butylhydroquinone, fluoroglycinol, pyrogallol, t-butylpyrogallol, allylated pyrogallol, polyallylated pyrogallol, 1,2,4-benzenetriol, 2,3,4-trihydroxybenzophenone, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene Examples of such allylated bisphenols include allylated bisphenol A, allylated bisphenol F, allylated phenol novolak, and allylated pyrogallol.

[0028] Specific examples of the amine-based curing agent include aliphatic amines such as ethylenediamine, 1,3-diaminopropane, 1,4-diaminopropane, hexamethylenediamine, 2,5-dimethylhexamethylenediamine, trimethylhexamethylenediamine, diethylenetriamine, iminobispropylamine, bis(hexamethylene)triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, N-hydroxyethylethylenediamine, and tetra(hydroxyethyl)ethylenediamine.

[0029] Examples of the polyetheramines include triethylene glycol diamine, tetraethylene glycol diamine, diethylene glycol bis(propylamine), polyoxypropylene diamine, and polyoxypropylene triamines. Examples of alicyclic amines include isophoronediamine, methacenediamine, N-aminoethylpiperazine, bis(4-amino-3-methyldicyclohexyl)methane, bis(aminomethyl)cyclohexane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro(5,5)undecane, and norbornenediamine. Examples of aromatic amines include tetrachloro-p-xylylenediamine, m-xylylenediamine, p-xylylenediamine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 2,4-diaminoanisole, 2,4-toluenediamine, 2,4-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diamino-1,2-diphenylethane, 2,4-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, m-aminophenol, m-aminobenzylamine, benzyldimethylamine, 2-dimethylaminomethylphenol, triethanolamine, methylbenzylamine, α-(m-aminophenyl)ethylamine, α-(p-aminophenyl)ethylamine, diaminodiethyldimethyldiphenylmethane, and α,α'-bis(4-aminophenyl)-p-diisopropylbenzene.

[0030] Specific examples of the acid anhydride curing agent include dodecenyl succinic anhydride, polyadipic anhydride, polyazelaic anhydride, polysebacic anhydride, poly(ethyloctadecanedioic) anhydride, poly(phenylhexadecanedioic) anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, methylhimic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, methylcyclohexene dicarboxylic anhydride, methylcyclohexene tetracarboxylic anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzyl methyl phthalate. Examples of the dianhydride include benzophenone tetracarboxylic acid anhydride, ethylene glycol bistrimellitate dianhydride, HET anhydride, Nadic anhydride, methylnadic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexane-1,2-dicarboxylic acid anhydride, 3,4-dimethyl-6-(2-methyl-1-propenyl)-4-cyclohexene-1,2-dicarboxylic acid anhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic acid dianhydride, and 1-methyl-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic acid dianhydride.

[0031] Examples of the amide-based curing agent include dicyandiamide and polyamide resins.

[0032] Examples of the tertiary amine include 1,8-diazabicyclo(5,4,0)undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol. Examples of the imidazole and its derivatives include 1-cyanoethyl-2-phenylimidazole, 2-phenylimidazole, 2-ethyl-4(5)-methylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyano-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazole], 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazole], 1-cyanoethyl ...phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2- Examples include 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and adducts of the above imidazoles with epoxy resins or polymer-encapsulated imidazole.

[0033] Examples of the organic phosphines include tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, and phenylphosphine. Examples of the phosphonium salts include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium ethyltriphenylborate, and tetrabutylphosphonium tetrabutylborate. Examples of the tetraphenylboron salts include 2-ethyl-4-methylimidazole tetraphenylborate and N-methylmorpholine tetraphenylborate.

[0034] These curing agents (B) may be used singly or as a mixture of two or more kinds in any combination and ratio.

[0035] Among the above-mentioned curing agents, it is preferable to use an acid anhydride curing agent (a compound having an acid anhydride group). When an acid anhydride curing agent is used, the viscosity of the composition tends to be low, so that a large amount of magnetic filler (C) can be added while maintaining a constant viscosity. Furthermore, acid anhydride curing agents generally have excellent electrical properties, mechanical properties, and particularly long-term reliability at high temperatures, and are widely used as electrical insulating materials, making them suitable for a variety of applications.

[0036] When the curing agent (B) is a phenol-based curing agent, an amine-based curing agent, or an acid anhydride-based curing agent, it is preferably used so that the equivalent ratio of the epoxy groups in the epoxy resin (A) to the functional groups in the curing agent (B) (functional groups in the curing agent (B) / epoxy groups in the epoxy resin (A)) is in the range of 0.8 to 2.0, and more preferably in the range of 0.8 to 1.5. When the equivalent ratio is in this range, the effects of residual unreacted epoxy groups or functional groups in the curing agent (B) are less likely to occur. When the curing agent (B) is an amide-based curing agent, a tertiary amine, imidazole and its derivatives, organic phosphines, phosphonium salts, tetraphenylboron salts, organic acid dihydrazides, boron halide amine complexes, polymercaptan-based curing agents, isocyanate-based curing agents, or blocked isocyanate-based curing agents, it is preferably used in an amount of 0.1 part by mass or more, more preferably 0.5 parts by mass or more, per 100 parts by mass of the epoxy resin (A), while it is preferably used in an amount of 20 parts by mass or less, more preferably 10 parts by mass or less. When the curing agent (B) is a dicyandiamine compound, it is preferably used in an amount of 0.1 part by mass or more, more preferably 0.5 part by mass or more, per 100 parts by mass of the epoxy resin (A), and is preferably used in an amount of 10 parts by mass or less, more preferably 6 parts by mass or less.

[0037] <Magnetic filler (C)> The magnetic filler (C) in the present epoxy resin composition has a circularity of 0.9 or less, preferably 0.85 or less, more preferably 0.8 or less, and even more preferably 0.75 or less, with the lower limit being 0.5. By setting the circularity within the above range, it is possible to produce a resin composition that is excellent in productivity, moldability, and relative magnetic permeability.

[0038] The circularity of the magnetic filler (C) can be determined, for example, by cutting out a cured product of an epoxy resin composition into a piece 5 mm wide and 18 mm long, measuring the average circularity of the magnetic filler on an SEM image, and using image analysis software ImageJ (National Institutes of Health, USA) to calculate the ratio L' / L of the actual circumferential circle L of the two-dimensional projection image of the filler when projected to the circumferential circle L' of a true circle having the same area as the projection image, and performing this process for any 20 magnetic fillers and calculating the average value. The circularity of the magnetic filler (C) does not change whether it is in the raw material stage or in the composition stage.

[0039] The magnetic filler (C) may be either a soft magnetic powder or a hard magnetic powder, but is preferably a soft magnetic powder from the viewpoint of suppressing uneven distribution of the magnetic filler (C).

[0040] Examples of the magnetic filler (C) include Fe-Mn ferrite, Mg-Zn ferrite, Mn-Zn ferrite, Mn-Mg ferrite, Cu-Zn ferrite, Mg-Mn-Sr ferrite, Ni-Zn ferrite, Ba-Zn ferrite, Ba-Mg ferrite, Ba-Ni ferrite, Ba-Co ferrite, Ba-Ni-Co ferrite, Y ferrite, iron oxide powder (III), triiron tetroxide, etc. Examples of suitable alloys include iron oxide powder, pure iron powder, iron alloy metal powders such as Fe-Si alloy powder, Fe-Si-Al alloy powder, Fe-Cr alloy powder, Fe-Cr-Si alloy powder, Fe-Ni-Cr alloy powder, Fe-Cr-Al alloy powder, Fe-Ni alloy powder, Fe-Ni-Mo alloy powder, Fe-Ni-Mo-Cu alloy powder, Fe-Co alloy powder, and Fe-Ni-Co alloy powder, and amorphous alloys such as Co-based amorphous alloys. Of these, Ni-Zn ferrite is preferred as the magnetic filler (C).

[0041] These magnetic fillers (C) may be used singly or as a mixture of two or more kinds in any combination and ratio.

[0042] The content of the magnetic filler (C) in the epoxy resin composition must exceed 85% by mass relative to the epoxy resin composition. While there is no particular upper limit, it is preferably 99% by mass or less. From the above perspectives, the content of the magnetic filler (C) is more preferably 85.2% by mass or more and 99% by mass or less, even more preferably 85.4% by mass or more and 98% by mass or less, and particularly preferably 85.6% by mass or more and 95% by mass or less.

[0043] The content of the magnetic filler (C) is preferably 60% by volume or more and 99% by volume or less, more preferably 65% ​​by volume or more and 95% by volume or less, and even more preferably 70% by volume or more and 90% by volume or less, based on the volume of the epoxy resin composition. When the content of the magnetic filler (C) is equal to or greater than the lower limit, the relative magnetic permeability of the composition is good. On the other hand, when the content of the magnetic filler (C) is equal to or less than the upper limit, the viscosity of the composition does not become too high, and handling becomes good.

[0044] The average particle size of the magnetic filler (C) is preferably 0.5 μm or more, more preferably 0.6 μm or more, even more preferably 0.7 μm or more, and particularly preferably 1.0 μm or more. On the other hand, the average particle size is preferably 30 μm or less, more preferably 20 μm or less, even more preferably 15 μm or less, and particularly preferably 10 μm or less.

[0045] Here, the method for measuring the average particle size of the magnetic filler (C) is not particularly limited, but a specific example of the measuring method is measurement using a laser diffraction particle size distribution analyzer (RODOS manufactured by SYMPATEC).

[0046] <Dispersant (D)> The epoxy resin composition further contains a dispersant (D), which improves the interfacial state between the epoxy resin (A) and the magnetic filler (C) and enhances compatibility, thereby reducing the viscosity of the composition and improving the dispersibility of the magnetic filler (C), thereby providing effects such as preventing aggregation and sedimentation of the magnetic filler (C).

[0047] Examples of the dispersant (D) include cationic dispersants such as alkylamine salts and quaternary ammonium salts having a substituent selected from aliphatic hydrocarbons and aromatic hydrocarbons, such as alkyltrimethylammonium salts, dialkyldimethylammonium chlorides, and alkylpyridinium chlorides; anionic dispersants such as sodium dodecylbenzelsulfonate, sodium laurate, and ammonium salts of polyoxyethylene alkyl ether sulfates; and nonionic dispersants such as organosiloxane dispersants, acetylene glycol, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, and polyoxyethylene alkylamides.

[0048] These dispersants (D) may be used singly or as a mixture of two or more kinds in any combination and ratio.

[0049] Among them, cationic dispersants are preferred as the dispersant (D), phosphate ester dispersants are more preferred, and compounds having a terminal phosphate group are even more preferred, which are particularly suitable when ferrite is used as the magnetic filler (C). Since the surface of the ferrite is nearly basic, the cationic dispersant is easily physically adsorbed, and as a result, the dispersant (D) can effectively exert a deaggregation effect due to steric hindrance of the polymer chain portion.

[0050] The content of the dispersant (D) in this embodiment is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.5% by mass or more and 3% by mass or less. When the content of dispersant (D) is equal to or greater than the lower limit, the magnetic filler (C) is easily dispersed uniformly in the composition. On the other hand, when the content of dispersant (D) is equal to or less than the upper limit, an increase in the thermal expansion coefficient due to phase separation between the epoxy resin (A) and the magnetic filler (C) is unlikely to occur.

[0051] <Other additives (E)> In addition to the above, the present epoxy resin composition may contain other additives selected from a curing accelerator, a coupling agent, an ultraviolet inhibitor, an antioxidant, a plasticizer, a flame retardant, a colorant, a flow improver, an antifoaming agent, an ion trapping agent, etc., as appropriate, within a range that does not impair the effects of the present invention (for example, 5% by mass or less).

[0052] These other additives (E) may be used singly or as a mixture of two or more kinds in any combination and ratio.

[0053] Furthermore, the present epoxy resin composition is preferably a solvent-free system. By using a solvent-free system, it is possible to prevent the solvent from volatilizing and generating voids when the composition is heat-cured. Note that the term "solvent" refers to a volatile component, and in this specification, this term encompasses water and organic solvents. A solvent-free liquid composition is one that does not substantially contain a solvent, and for example, the solvent content is preferably less than 3% by mass, more preferably less than 1% by mass, and even more preferably 0% by mass.

[0054] <Method of producing epoxy resin composition> The epoxy resin composition can be produced, for example, by stirring the ingredients using a stirring device such as a planetary mixer, a three-roll mill, a rotary mixer, a high-speed rotary mixer, etc. Among these, by kneading with a mixer that has an appropriately high shear force, such as a planetary mixer, a large amount of low-circularity magnetic filler (C) can be dispersed, and moldability and relative magnetic permeability can be improved. The epoxy resin composition may be degassed after production, etc. For example, degassing may be performed by leaving the composition to stand, by centrifugal separation, by vacuum degassing, by stirring, or by a combination of these methods.

[0055] The cured product of the epoxy resin composition can be obtained by curing the epoxy resin composition. There are no particular limitations on the curing method, and the product can be obtained, for example, by thermal curing. The thermal curing conditions may be those used for ordinary epoxy resins, such as a curing temperature in the range of 120 to 240°C and a curing time of about 5 to 120 minutes.

[0056] The glass transition temperature (Tg) of the epoxy resin composition obtained in this manner when cured is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher, from the viewpoint of durability of the cured product, with the upper limit being 200°C.

[0057] The glass transition temperature (Tg) of the cured product obtained by curing such an epoxy resin composition to a gel fraction of 80% or more can be measured using a thermomechanical analyzer (TMA). Specifically, measurements are performed using the same equipment and conditions as those used to evaluate the thermal expansion coefficient described below, and a graph is created with temperature on the X axis and the linear expansion coefficient on the Y axis. CTE'1 is determined from the slope of the tangent line from 15 to 75°C, and CTE'2 is determined from the slope of the tangent line from 150 to 200°C. The glass transition temperature (Tg) (°C) is determined from the intersection of CTE'1 and CTE'2.

[0058] Furthermore, the average coefficient of thermal expansion (CTE) of the present epoxy resin composition when cured is preferably from 0 ppm / K to 2000 ppm / K, more preferably from 2 ppm / K to 1000 ppm / K, even more preferably from 4 ppm / K to 60 ppm / K, and particularly preferably from 10 ppm / K to 50 ppm / K.

[0059] The average coefficient of thermal expansion of the cured product obtained by curing such an epoxy resin composition to a gel fraction of 80% or more can be measured by thermomechanical analysis according to JIS K7197 (2012). Specifically, measurements were performed using a thermomechanical analyzer (TMA SS7100, manufactured by SII NanoTechnology) using the compression method. Specifically, the cured product was cut into pieces measuring φ6 mm x 10 mm, and the temperature was measured using the thermomechanical analyzer by decreasing the temperature from 200 °C to 20 °C at a rate of 5 °C / min. The temperature change in the change in sample length from 25 to 100 °C was measured, and the slope of the tangent was taken as the average coefficient of thermal expansion (CTE).

[0060] The upper limit of the viscosity of the present epoxy resin composition at room temperature (23°C) is 1000 Pa / s or less, preferably 800 Pa / s or less, more preferably 500 Pa / s or less, even more preferably 300 Pa / s or less, and particularly preferably 250 Pa / s or less. The lower limit of the viscosity of the present epoxy resin composition is usually 1 Pa / s or more, preferably 2 Pa / s or more, more preferably 5 Pa / s or more, even more preferably 8 Pa / s or more, and particularly preferably 10 Pa / s or less. By setting the viscosity within the above range, the epoxy resin composition has excellent moldability. In the present epoxy resin composition, the viscosity can be adjusted to fall within the above range by kneading the composition with a magnetic filler (C) having a low circularity and preferably with an appropriate dispersant (D) in a mixer with an appropriately high shear force.

[0061] The viscosity of such an epoxy resin composition can be measured using a Brookfield type rotational viscometer. When the viscosity is 0.1 to 100 Pa·s, an "LVDV-1 Pri" Brookfield viscometer with spindles S64 and S63 is used, and when the viscosity exceeds 100 Pa·s, an "HBDV-E" Brookfield viscometer with spindle S-07 is used. The viscosity measured at 5 rpm is used as the representative viscosity value for each sample.

[0062] The relative magnetic permeability at a frequency of 100 MHz when the epoxy resin composition is cured is 14 or more, preferably 14.5 or more, more preferably 15 or more, even more preferably 15.5 or more, and particularly preferably 16 or more, with the upper limit being 20 or less. In the present epoxy resin composition, the relative magnetic permeability can be adjusted to fall within the above range by using a magnetic filler (C) with low circularity and preferably an appropriate dispersant (D) and kneading them in a mixer with an appropriately high shear force.

[0063] The relative magnetic permeability of the present epoxy resin composition can be measured using a Belts Network Analyzer (VNA) ("HP8362B" manufactured by Agilent Technologies) by the three-turn coil method at room temperature of 23°C and a frequency of 100 MHz.

[0064] Because this epoxy resin composition contains a high filling rate of the magnetic filler (C) and has low viscosity at room temperature, it can be used as a magnetic paste for a variety of applications, including inductor materials, circuit board materials, noise suppression shields, wireless power transfer, transformers, motors, antennas, and other electrical and electronic components. In particular, the inductor materials and substrate materials obtained from the present epoxy resin composition can be used as wiring board materials. The wiring boards can be used to manufacture various semiconductor devices, and can be applied to electronic devices such as computers, mobile phones, and digital cameras, other electrical appliances such as televisions, and transportation equipment such as automobiles, trains, ships, and aircraft.

[0065] Furthermore, since the cured product of the present epoxy resin composition contains a high content of magnetic filler, it has a high relative magnetic permeability and can be suitably used as a variety of materials. For example, it is suitable as an inductor material. A substrate using this inductor material can be used as a wiring board for mounting electronic components such as semiconductor chips, and further, the wiring board can be used as a multilayer printed wiring board. [Example]

[0066] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by mass.

[0067] First, the following ingredients were prepared:

[0068] <Epoxy resin (A)> (A-1): Mitsubishi Chemical Corporation, product name "YED188" (alkyl monoglycidyl ether, epoxy equivalent: 185g / equivalent) (A-2): Mitsubishi Chemical Corporation, product name "JER188" (p-aminophenol type epoxy resin, epoxy equivalent: 97 g / equivalent) (A-3): Nippon Steel Chemical & Material Co., Ltd., product name "ZX-1059" (alkyl monoglycidyl ether, epoxy equivalent: 170 g / equivalent) (A-4): Japan Epoxy Resin Co., Ltd., product name "jER188" (bisphenol F type epoxy resin, epoxy equivalent: 97g / equivalent)

[0069] <Curing agent (B)> (B-1): New Japan Chemical Co., Ltd., product name "HNA-100" (hydrogenated methyl nadic anhydride, amine equivalent: 100g) (B-2): Shikoku Chemicals Corporation, product name "2P4MZ" (2-phenyl-4-methylimidazole, amine equivalent: 100g)

[0070] <Magnetic filler (C)> (C-1): Toda Kogyo Co., Ltd., product name "BSN-125" (Ni-Zn soft ferrite, average particle size: 3.25 μm) (C-2): Powderdeck Co., Ltd., product name "Magnetic Powder d" (Ni-Zn soft ferrite, average particle size: 3.25 μm)

[0071] <Dispersant (D)> (D-1): BYK Japan, wetting and dispersing agent, product name "BYK-W9010" (phosphate polyester (containing terminal phosphate groups), solvent-free)

[0072] <Other Additives (E)> (E-1): Phosphorus-based curing accelerator, product name "Hishicolin PX-4MP" (methyltributylphosphonium-dimethylphosphate), manufactured by Nippon Chemical Industry Co., Ltd.

[0073] Example 1 The materials were weighed out according to the formulation shown in Table 1 below, and premixed at 16 rpm for 1 minute using a planetary mixer (PRIMIX, Hivis Dispermix 3D-2 type) and then mixed at 43 rpm for 5 minutes to prepare a composition. The resin composition was then cast onto the release surface of a polyethylene terephthalate (PET) film (Mitsubishi Chemical Corporation, "MRF-100") having a release layer, uniformly coated to a layer thickness of 200 μm, and cured at 80°C for 2 hours. The resulting cured product was peeled off from the PET film and heat-treated at 120°C for 2 hours to cure to a gel fraction of 80% or more, thereby obtaining a cured product.

[0074] Comparative Examples 1 to 4 In Example 1, materials were weighed according to the formulation shown in Table 1 below, and a composition and a cured product thereof were obtained in the same manner as in Example 1 using a vacuum mixer (Thinky Corporation, "Awatori Rentaro ARV-310P").

[0075] The compositions prepared in the above Examples and Comparative Examples and their cured products were subjected to the following measurements and evaluations, the results of which are shown in Table 1 below.

[0076] <Glass transition temperature (Tg)> The glass transition temperature (Tg) of the cured product obtained by curing the composition to a gel fraction of 80% or more was measured using a thermomechanical analyzer (TMA). Specifically, measurements were performed using the same equipment and conditions as those used to evaluate the thermal expansion coefficient described below, and a graph was created with temperature on the X-axis and the linear expansion coefficient on the Y-axis. "CTE'1" was determined from the slope of the tangent line of this graph from 15 to 75°C, and "CTE'2" was determined from the slope of the tangent line from 150 to 200°C, and the glass transition temperature (Tg) (°C) was determined from the intersection of CTE'1 and CTE'2.

[0077] <Average coefficient of thermal expansion (CTE)> The average coefficient of thermal expansion of the cured product obtained by curing the composition to a gel fraction of 80% or more was measured using a thermomechanical analyzer (TMA SS7100, manufactured by SII NanoTechnology) by the compression method in accordance with JIS K7197 (2012). Specifically, the cured product was cut into pieces φ6 mm x 10 mm in size and measured by the compression method using the thermomechanical analyzer, decreasing the temperature from 200 °C to 20 °C at a rate of 5 °C / min. The temperature change in the sample length from 25 to 100 °C was measured, and the slope of the tangent was taken as the average coefficient of thermal expansion (CTE) (ppm / K).

[0078] <Viscosity of the composition> The viscosity of the composition at 23°C was measured using a Brookfield "LVDV-1 Pri" rotational viscometer with spindles S64 and S63 when the viscosity was 0.1 to 100 Pa·s, and a Brookfield "HBDV-E" rotational viscometer with spindle S-07 when the viscosity exceeded 100 Pa·s. The value measured at 5 rpm was used as the representative viscosity value for each sample.

[0079] <Relative permeability> The relative magnetic permeability (MHz) of the composition was measured at room temperature of 23° C. and a frequency of 100 MHz by a 3-turn coil method using a Belts Network Analyzer (VNA) (manufactured by Agilent Technologies, "HP8362B").

[0080] <Circularity> The cured product was cut into a piece 5 mm wide and 18 mm long, and the average circularity of the magnetic filler was measured using an SEM image. Using the image analysis software ImageJ (National Institutes of Health, USA), the ratio L' / L of the actual circumferential circle L of the two-dimensional projected image of the filler to the circumferential circle L' of a perfect circle having the same area as the projected image was calculated. This was performed for 20 random magnetic fillers, and the average value was calculated.

[0081] <Moldability> At room temperature of 23°C, each uncured resin composition was poured into a "Screw Cap Bottle Transparent Cap GL-32" (manufactured by DWK Life Science) until it was completely filled to the brim, and after leaving it to stand for 60 seconds, it was exposed to light to check the state of filling inside, and evaluated according to the following criteria. ◯: The resin composition is filled along the grooves of the screw. ×: Air bubbles remain inside.

[0082] [Table 1]

[0083] As shown in Example 1 above, the epoxy resin composition contained a specific amount of magnetic filler having a specific circularity, and thus had excellent magnetic permeability and moldability. On the other hand, Comparative Example 1, which contains a magnetic filler without a specific circularity, Comparative Example 2, which has a specific viscosity or higher, and Comparative Examples 3 and 4, which do not contain a specific amount of low-circularity magnetic filler, were not excellent in all respects of magnetic permeability and moldability. [Industrial Applicability]

[0084] The epoxy resin composition of the present invention has excellent moldability and magnetic permeability, and can therefore be suitably used in electric and electronic parts (for example, inductors and circuit boards).

Claims

1. An epoxy resin composition comprising an epoxy resin (A), a curing agent (B), and a magnetic filler (C) having a circularity of 0.9 or less, the content of the magnetic filler (C) is more than 85% by mass relative to the epoxy resin composition, The epoxy resin composition has a viscosity of 1000 Pa s or less when measured at 23°C and 5 rpm, and a cured product of the epoxy resin composition has a relative magnetic permeability of 14 or more at a frequency of 100 MHz.

2. 2. The epoxy resin composition according to claim 1, further comprising a dispersant having a terminal phosphate group.

3. 2. The epoxy resin composition according to claim 1, wherein the glass transition temperature of the epoxy resin composition is 100°C or higher.

4. The epoxy resin composition of claim 1 , wherein the epoxy resin composition is solvent-free.

5. A cured product comprising the epoxy resin composition according to any one of claims 1 to 4.

6. An electric or electronic part comprising the cured product according to claim 5.

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