Epoxy resin hardener, epoxy resin composition, sealing material, conductive material, thermally conductive material, adhesive for camera module, structural adhesive, matrix resin for fiber-reinforced plastic, impregnation fixing material, interlayer insulating film, film-type solder resist, sealing sheet, conductive film, anisotropic conductive film, thermally conductive film, and method for producing dyed cured product

Abstract

To provide an epoxy resin hardener or the like that imparts superior stability and reactivity to an epoxy resin composition mixed with a low-molecular-weight epoxy compound, a solvent, or a low-molecular-weight acryl compound, and that enables provision of superior appearance even in fine regions when curing an epoxy resin composition containing a filler.SOLUTION: An epoxy resin hardener comprises: a core (A) containing a nitrogen-containing compound; and a layer (B) that covers the core (A). In the epoxy resin hardener, after staining the epoxy resin hardener with ruthenium tetroxide and osmium tetroxide, observing it via transmission electron microscopy, and deriving a luminance graph through image processing, the inside of the layer (B) includes a region having luminance α, wherein the luminance α is higher than a luminance β at the outermost surface of the layer (B) and a luminance γ at the boundary between the layer (B) and the core (A).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an epoxy resin curing agent, an epoxy resin composition, a sealing material, a conductive material, a heat conductive material, an adhesive for a camera module, a structural adhesive, a matrix resin for a fiber reinforced plastic, an impregnating and fixing material, an interlayer insulating film, a film type solder resist, a sealing sheet, a conductive film, an anisotropic conductive film, a heat conductive film, and a method for producing a dyed cured product.

Background Art

[0002] Epoxy resins are used in a wide range of applications as epoxy resin compositions containing an epoxy resin curing agent, such as insulating materials, sealing materials, adhesives, conductive materials, matrix resins for fiber reinforced plastics, impregnating and fixing agents for motor coils, and structural adhesives for automobiles, for electrical and electronic components such as semiconductor packages and camera modules.

[0003] In recent years, in semiconductor packages, film materials such as underfill materials for protecting bump connection portions and chip circuit surfaces, die attach films for chip bonding, films for forming interlayer insulating layers, and films for forming solder resist layers are used, and the epoxy resin composition is used as the aforementioned underfill materials and various film materials.

[0004] As an epoxy resin composition applicable to an underfill material, for example, an epoxy resin composition containing a microcapsule type curing agent is disclosed (see, for example, Patent Document 1). Further, as an epoxy resin composition applicable to a film material, for example, an epoxy resin composition containing a microcapsule type curing agent is disclosed (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] Epoxy resin compositions are used in various applications as described above, and the components in the compositions are appropriately selected for each application. As typical compositional systems that can be envisioned, for example, in the case of underfill materials, an epoxy resin composition containing a low molecular weight epoxy compound as a reactive diluent can be mentioned. In the case of film materials, an epoxy resin composition containing a solvent such as methyl ethyl ketone (MEK) or cyclohexanone during varnish preparation can be mentioned. In the case of dual-curing adhesives that cure with both light and heat, an epoxy resin composition containing a low molecular weight acrylic compound can be mentioned. As epoxy resin curing agents, those that can impart storage stability and reactivity are required in such various compositional systems.

[0007] In addition, when the epoxy resin composition contains a filler, in the cured product obtained by curing the epoxy resin composition, an excellent appearance, that is, an appearance in which the filler is uniformly dispersed in the cured product is required. In recent years, with the high functionality of electronic materials, an excellent appearance in a minute region has been required more than ever. In other words, even aggregates of fillers and curing agents that could be evaluated as relatively small sizes at the conventional level may be regarded as a problem in terms of appearance in recent years.

[0008] The microcapsule type curing agent and the epoxy resin composition containing the same disclosed in Patent Documents 1 and 2 still have room for improvement from the above viewpoints.

[0009] An object of the present invention is to provide an epoxy resin curing agent or the like that imparts excellent stability and reactivity to an epoxy resin composition mixed with a low molecular weight epoxy compound, a solvent, or a low molecular weight acrylic compound, and can impart an excellent appearance even in a minute region when curing an epoxy resin composition containing a filler. MEANS FOR SOLVING THE PROBLEM

[0010] As a result of intensive studies, the present inventors have found that an epoxy resin curing agent having a predetermined configuration can solve the above problems, and have thus completed the present invention. That is, the present invention includes the following aspects. [1] A core (A) containing a nitrogen-containing compound, A layer (B) covering the core (A), An epoxy resin curing agent having: when the epoxy resin curing agent is stained with ruthenium tetroxide and osmium tetroxide and observed with a transmission electron microscope to obtain a luminance graph by image processing, the inside of the layer (B) has a region having a luminance α, and the luminance α is higher than the luminance β at the outermost part of the layer (B) and the luminance γ at the boundary between the layer (B) and the core (A). [2] The epoxy resin curing agent according to [1], wherein the core (A) contains 0.001 to 20% by mass of an amine compound (a) having a molecular weight of 50 to 300. [3] The epoxy resin curing agent according to [1] or [2], wherein the core (A) contains at least one selected from the group consisting of imidazoles, aliphatic amine compounds, and cyclic amine compounds containing a tertiary amine. [4] The epoxy resin curing agent according to any one of [1] to [3], wherein the core (A) contains an imidazole-based amine adduct compound. [5] The particle size D of 50% undersize cumulative fraction of the core (A) 50 is more than 0.3 μm and 12 μm or less. The epoxy resin curing agent according to any one of [1] to [4]. [6] The ratio of the particle size D of 99% undersize cumulative fraction of the core (A) 99 to the D 50 is 8 or less as D 99 / D 50 The epoxy resin curing agent according to [5]. [7] ​​​​The value obtained by multiplying the specific surface area value Y (m 2 / g) of the core (A) by the D 50 (μm) is 3.0 or more and 9.0 or less, and the epoxy resin curing agent according to [5] or [6]. [8] The value obtained by multiplying the specific surface area value Y (m 2 / g) of the core (A) by the D 50 (μm) is more than 9.0 and 18.0 or less, and the epoxy resin curing agent according to any one of [5] to [7]. [9] [1] to [8], and an epoxy resin composition containing an epoxy resin (C).

[10] The mass ratio of the epoxy resin curing agent to the epoxy resin (C) is 0.1:100 to 1000:100 as the epoxy resin curing agent:epoxy resin (C), and the epoxy resin composition according to [9].

[11] The epoxy resin composition according to [9] or

[10] , further containing an alcohol compound (D) represented by the following formula (1).

Chemical formula

[12] The content of the alcohol compound (D) is 0.0001% by mass or more and 5% by mass or less based on the total amount of the epoxy resin composition, and the epoxy resin composition according to

[11] .

[13] The epoxy resin composition according to

[11] or

[12] , wherein the alcohol compound (D) contains at least one selected from the group consisting of 3-phenoxy-1-propanol, 3-phenoxy-1,2-propanediol, 3-phenoxy-1,3-propanediol, 3-(ortho-tolyloxy)-1,2-propanediol, 3-(2-methoxyphenoxy)propane-1,2-diol, bisphenol A (3-hydroxypropyl) glycidyl ether, and bisphenol A (2,3-dihydroxypropyl) glycidyl ether.

[14] The core (A) contains 0.001 to 20% by mass of an amine compound (a) having a molecular weight of 50 to 300. The epoxy resin composition according to any one of [9] to

[13] , wherein the amine compound (a) contains at least one selected from the group consisting of imidazoles, aliphatic amine compounds, and cyclic amine compounds containing a tertiary amine.

[15] A sealing material containing the epoxy resin curing agent according to any one of [1] to [8] or the epoxy resin composition according to any one of [9] to

[14] .

[16] A conductive material containing the epoxy resin curing agent according to any one of [1] to [8] or the epoxy resin composition according to any one of [9] to

[14] .

[17] A heat conductive material containing the epoxy resin curing agent according to any one of [1] to [8] or the epoxy resin composition according to any one of [9] to

[14] .

[18] An insulating material containing the epoxy resin curing agent according to any one of [1] to [8] or the epoxy resin composition according to any one of [9] to

[14] .

[19] An adhesive for a camera module containing the epoxy resin curing agent according to any one of [1] to [8] or the epoxy resin composition according to any one of [9] to

[14] .

[20] A structural adhesive comprising an epoxy resin curing agent described in any one of [1] to [8] or an epoxy resin composition described in any one of [9] to

[14] .

[21] A matrix resin for fiber-reinforced plastics comprising an epoxy resin curing agent described in any one of [1] to [8] or an epoxy resin composition described in any one of [9] to

[14] .

[22] An impregnating and fixing material comprising an epoxy resin curing agent described in any one of [1] to [8] or an epoxy resin composition described in any one of [9] to

[14] .

[23] An interlayer insulating film comprising an epoxy resin curing agent described in any one of [1] to [8] or an epoxy resin composition described in any one of [9] to

[14] .

[24] A film-type solder resist comprising an epoxy resin curing agent described in any one of [1] to [8] or an epoxy resin composition described in any one of [9] to

[14] .

[25] A sealing sheet comprising an epoxy resin curing agent described in any one of [1] to [8] or an epoxy resin composition described in any one of [9] to

[14] .

[26] A conductive film comprising an epoxy resin curing agent described in any one of [1] to [8] or an epoxy resin composition described in any one of [9] to

[14] .

[27] An anisotropic conductive film comprising an epoxy resin curing agent described in any one of [1] to [8] or an epoxy resin composition described in any one of [9] to

[14] .

[28] A thermally conductive film comprising an epoxy resin curing agent described in any one of [1] to [8] or an epoxy resin composition described in any one of [9] to

[14] .

[29] A step (S1) of electron staining an epoxy resin curing agent having a core (A) and a layer (B) covering the core (A) with ruthenium tetroxide; A step (S2) of obtaining a cured product of the composition containing the epoxy resin curing agent that has undergone the step (S1); A step (S3) of electron-staining a section of the cured product with osmium tetroxide; A method for producing a stained cured product, comprising the above steps.

Advantages of the Invention

[0011] According to the present invention, it is possible to provide an epoxy resin curing agent or the like that imparts excellent stability and reactivity to an epoxy resin composition mixed with a low-molecular epoxy compound, a solvent, or a low-molecular acrylic compound, and imparts an excellent appearance even in a minute region when curing an epoxy resin composition containing a filler.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0013] Hereinafter, the mode for carrying out the present invention (hereinafter also referred to as "the present embodiment") will be described in detail. The following present embodiment is an exemplification for explaining the present invention, and is not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of its gist.

[0014] 〔Epoxy Resin Hardener〕 The epoxy resin hardener of the present embodiment includes a core (A) containing a nitrogen-containing compound, a layer (B) covering the core (A), and after staining the epoxy resin hardener with ruthenium tetroxide and osmium tetroxide and observing it with a transmission electron microscope (hereinafter also referred to as "TEM") to obtain a luminance graph by image processing, the inside of the layer (B) has a region having a luminance α, and the luminance α is higher than the luminance β at the outermost part of the layer (B) and the luminance γ at the boundary between the layer (B) and the core (A) (hereinafter, the layer (B) having the above region is also referred to as "having a desired stainability"). Since the epoxy resin hardener of the present embodiment is configured as described above, even when it is mixed with a low molecular weight epoxy compound, a solvent or a low molecular weight acrylic compound to form an epoxy resin composition, excellent stability and reactivity can be imparted, and an epoxy resin composition containing a filler can be formed. When it is cured, an excellent appearance can be imparted even in minute regions. In the present embodiment, it is sufficient that at least a part of the epoxy resin hardener has a desired stainability, and the more regions having a desired stainability, the better. In particular, it is preferable that the entire region of the epoxy resin hardener has a desired stainability.

[0015] (Staining Method and TEM Observation) The epoxy resin curing agent of this embodiment will be described below in terms of the staining method and the observation method after staining. First, 10.6 mL of the main agent (Quetol 812, manufactured by Nisshin EM Co., Ltd.), 9.4 mL of the curing agent (Methyl nadic anhydride: MNA, manufactured by Nisshin EM Co., Ltd.), and 0.34 mL of the reaction accelerator (2,4,6-Tris(dimethyl amino methyl)phenol, manufactured by Nisshin EM Co., Ltd.: DMP-30) were mixed and stirred with a stirrer for 15 minutes, and then the air bubbles were removed by vacuum degassing to obtain an epoxy resin composition for staining. Next, the epoxy resin curing agent of this embodiment was electron-stained by coexisting with ruthenium tetroxide for 10 minutes in a sealed and light-shielded container at room temperature and atmospheric pressure, and then mixed with the above epoxy resin composition for staining and cured at 40°C for 42 hours. After preparing an 80-nm section of the cured product embedded with the epoxy resin curing agent using an ultramicrotome, the section was coexisted with osmium tetroxide for 2 hours in a sealed and light-shielded container at room temperature and atmospheric pressure to obtain an observation sample electron-stained with osmium tetroxide vapor. An electron beam was irradiated onto the observation sample with a TEM and adjusted so that the focus matched the material, and observation was performed at an acceleration voltage of 120 kV and a magnification of 30,000 times to obtain a TEM observation image. These operations can be more specifically carried out based on the methods described in the examples described later. (Obtaining the luminance graph of layer (B) by image processing) The obtained TEM observation image was loaded into the image analysis software ImageJ, and after applying a median filter (Radius 2.0 pixels), a line segment was drawn from the outermost part of layer (B) to include the boundary between core (A) and layer (B), and the luminance was graphed along the line segment. These operations can be more specifically carried out based on the methods described in the examples described later.

[0016] [Core (A) containing a nitrogen-containing compound] The core (A) containing a nitrogen-containing compound is a particle or a group of particles containing a nitrogen-containing compound (hereinafter, these are also collectively referred to as "core (A) particles"). The nitrogen-containing compound is not particularly limited, and examples thereof include low molecular weight amine compounds, amine adduct compounds, modified polyamine compounds, aliphatic polyamine compounds, heterocyclic polyamine compounds, alicyclic polyamine compounds, aromatic amine compounds, polyamideamine compounds, ketimine compounds, urethaneamine compounds, amide compounds, and the like. These may be used alone or in combination of two or more kinds.

[0017] Examples of the low molecular weight amine compound include, but are not limited to, compounds having no tertiary amines such as methylamine, ethylamine, propylamine, butylamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, ethanolamine, propanolamine, cyclohexylamine, isophoronediamine, aniline, toluidine, diaminodiphenylmethane, diaminodiphenylsulfone, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, dimethanolamine, diethanolamine, dipropanolamine, dicyclohexylamine, piperidine, piperidone, diphenylamine, phenylmethylamine, phenylethylamine; amino alcohols such as 2-dimethylaminoethanol, 1-methyl-2-dimethylaminoethanol, 1-phenoxymethyl-2-dimethylaminoethanol, 2-diethylaminoethanol, 1-butoxymethyl-2-dimethylaminoethanol, methyldiethanolamine, triethanolamine, N-β-hydroxyethylmorpholine; aminophenols such as 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol; imidazoles such as imidazole, 2-methylimidazole, 4-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-aminoethyl-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-ethyl-4-methylimidazole, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazole, 1-(2-hydroxy-3-butoxypropyl)-2-ethyl-4-methylimidazole;1-(2-Hydroxy-3-phenoxypropyl)-2-phenylimidazoline, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazoline, 2-methylimidazoline, 2,4-dimethylimidazoline, 2-ethylimidazoline, 2-ethyl-4-methylimidazoline, 2-benzylimidazoline, 2-phenylimidazoline, 2-(o-tolyl)-imidazoline, tetramethylene-bis-imidazoline, 1,1,3-trimethyl-1,4-tetramethylene-bis-imidazoline, 1,3,3-trimethyl-1,4-tetramethylene-bis-imidazoline, 1,1,3-trimethyl-1,4-tetramethylene-bis-4-methylimidazoline, 1,3,3-trimethyl-1,4-tetramethylene-bis-4-methylimidazoline, 1,2-phenylene-bis-imidazoline, 1,3-phenylene-bis-imidazoline, 1,4-phenylene-bis-imidazoline, 1,4-phenylene-bis-4-methylimidazoline and other imidazolines; trimethylamine, triethylamine, benzyldimethylamine, N,N-dimethyl-ethylamine, N,N-dimethyl-butylamine, N,N-dimethyldecylamine, N,N-dimethyl-m-toluidine, N,N-dimethyl-p-toluidine, 2,6,10-trimethyl-2,6,10-triazoundecane, N,N'-dimethylpiperazine, 1,4-diazabicyclo[2.2.2]octane (DABCO), 1-azabicyclo[2.2.2]octan-3-one, 1,8-diazabicyclo(5,4,0)-undecene-7, 1,5-diazabicyclo(4,3,0)-nonene-5, hexamethylenetetramine, dimethylaminopropylamine, diethylaminopropylamine, dipropylaminopropylamine, dibutylaminopropylamine, dimethylaminoethylamine, diethylaminoethylamine, dipropylaminoethylamine, dibutylaminoethylamine, N-methylpiperazine, N-aminoethylpiperazine, diethylaminoethylpiperazine, 2-dimethylaminopyridine, 4-dimethylaminopyridine and other tertiary aminoamines; 2-dimethylaminoethanethiol, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptopyridine, 4-mercaptopyridine and other aminomercaptans;Amino carboxylic acids such as N,N-dimethylaminobenzoic acid, N,N-dimethylglycine, nicotinic acid, isonicotinic acid, picolinic acid; amino hydrazides such as N,N-dimethylglycine hydrazide, nicotinic acid hydrazide, isonicotinic acid hydrazide, etc. These may be used alone or in combination of two or more.

[0018] Examples of the amine adduct compounds include, but are not limited to, compounds obtained by reacting any one or more of carboxylic acid compounds, sulfonic acid compounds, urea compounds, isocyanate compounds, and epoxy resins with the above-mentioned low-molecular amine compounds. In the present embodiment, the amine adduct compound preferably includes an imidazole-based amine adduct compound. The imidazole-based amine adduct may be a reaction product of imidazoles with any one or more of, for example, carboxylic acid compounds, sulfonic acid compounds, urea compounds, isocyanate compounds, and epoxy resins. From the viewpoint of the formability of layer (B), the imidazole-based amine adduct compound preferably includes a reaction product of imidazoles and an epoxy resin, and from the viewpoint of mechanical strength, it is particularly preferable to include a reaction product of imidazole and a bisphenol-type epoxy resin.

[0019] Examples of the carboxylic acid compounds include, but are not limited to, succinic acid, adipic acid, sebacic acid, phthalic acid, dimer acid, etc.

[0020] Examples of the sulfonic acid compounds include, but are not limited to, ethanesulfonic acid, p-toluenesulfonic acid, etc.

[0021] Examples of the urea compounds include, but are not limited to, urea, methylurea, dimethylurea, ethylurea, t-butylurea, etc.

[0022] Examples of the isocyanate compounds include, but are not limited to, aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, aliphatic triisocyanates, polyisocyanates, etc. Examples of the aliphatic diisocyanate include, but are not limited to, ethylene diisocyanate, propylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, etc. Examples of the alicyclic diisocyanate include, but are not limited to, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, norbornane diisocyanate, 1,4-isocyanatocyclohexane, 1,3-bis(isocyanatomethyl)-cyclohexane, 1,3-bis(2-isocyanatopropyl-2-yl)-cyclohexane, etc. Examples of the aromatic diisocyanate include, but are not limited to, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylene diisocyanate, 1,5-naphthalene diisocyanate, etc. Examples of the aliphatic triisocyanate include, but are not limited to, 1,6,11-undecane triisocyanate, 1,8-diisocyanate-4-isocyanatemethyloctane, 1,3,6-triisocyanatemethylhexane, etc. Examples of the polyisocyanate include, but are not limited to, polymethylene polyphenyl polyisocyanate and polyisocyanates derived from the diisocyanate compounds. Examples of the polyisocyanates derived from the diisocyanate compounds include isocyanurate-type polyisocyanates, biuret-type polyisocyanates, urethane-type polyisocyanates, allophanate-type polyisocyanates, carbodiimide-type polyisocyanates, etc.

[0023] Examples of the epoxy resin include, but are not limited to, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, bisphenol M type epoxy resin, bisphenol P type epoxy resin, tetrabromobisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, tetrabromobiphenyl type epoxy resin, diphenyl ether type epoxy resin, benzophenone type epoxy resin, phenyl benzoate type epoxy resin, diphenyl sulfide type epoxy resin, diphenyl sulfoxide type epoxy resin, diphenyl sulfone type epoxy resin, diphenyl disulfide type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, hydroquinone type epoxy resin, methyl hydroquinone type epoxy resin, dibutyl hydroquinone type epoxy resin, resorcin type epoxy resin, methyl resorcin type epoxy resin, catechol type epoxy resin and other bifunctional epoxy resins; N,N-diglycidylaminobenzene type epoxy resin, triazine type epoxy resin and other trifunctional epoxy resins; tetraglycidyldiaminodiphenylmethane type epoxy resin, diaminobenzene type epoxy resin and other tetrafunctional epoxy resins; phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene type epoxy resin, naphthol aralkyl type epoxy resin, brominated phenol novolac type epoxy resin and other polyfunctional epoxy resins; butyl glycidyl ether, hexyl glycidyl ether, phenyl glycidyl ether, allyl glycidyl ether, para-tert-butylphenyl glycidyl ether, ethylene oxide, propylene oxide, para xylyl glycidyl ether, glycidyl acetate, glycidyl butyrate, glycidyl hexoate, glycidyl benzoate and other monoepoxy compounds, and alicyclic epoxy resins. These may be used alone or in combination of two or more kinds.

[0024] Examples of the amide compounds include, but are not limited to, guanidine compounds such as dicyandiamide and its derivatives, compounds obtained by adding an acid anhydride to an amine compound, and hydrazide compounds. Examples of the hydrazide compounds include, but are not limited to, succinic acid dihydrazide, adipic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, p - hydroxybenzoic acid hydrazide, salicylic acid hydrazide, phenylaminopropionic acid hydrazide, maleic acid dihydrazide, and the like. Examples of the guanidine compounds include, but are not limited to, dicyandiamide, methylguanidine, ethylguanidine, propylguanidine, butylguanidine, dimethylguanidine, trimethylguanidine, phenylguanidine, diphenylguanidine, toluyguanidine, and the like. These may be used alone or in combination of two or more.

[0025] Among these compounds having nitrogen atoms, from the viewpoint of achieving both the reactivity during thermosetting and the stability during storage when used as an epoxy resin composition, low - molecular - weight amine compounds, amine adduct - type compounds, and amide compounds are preferred, low - molecular - weight amine compounds and amine adduct - type compounds are more preferred, and it is particularly preferred to contain both a low - molecular - weight amine and an amine adduct - type compound.

[0026] The low - molecular - weight amine compound preferably contains an amine compound (a) having a molecular weight of 50 to 300. That is, when used as an epoxy resin composition, from the viewpoint of suppressing thickening by passing through the layer (B) from the core (A) and reacting with the epoxy resin, a molecular weight of 50 or more is preferred, a molecular weight of 60 or more is more preferred, and a molecular weight of 70 or more is even more preferred. Also, from the viewpoint of exhibiting high reactivity due to excellent diffusibility, a molecular weight of 300 or less is preferred, a molecular weight of 270 or less is more preferred, and a molecular weight of 240 or less is even more preferred.

[0027] As the amine compound (a), from the viewpoint of excellent reactivity with an epoxy resin, imidazoles, aliphatic amine compounds, and cyclic amine compounds containing a tertiary amine are preferable. As the imidazole-based compound, imidazole, 2-methylimidazole, 4-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, and 2-phenylimidazole are more preferable. As the aliphatic amine compound, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, ethanolamine, propanolamine, cyclohexylamine, isophoronediamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, and piperidine are more preferable. As the cyclic amine compound containing a tertiary amine, 1,4-diazabicyclo[2.2.2]octane, 1-azabicyclo[2.2.2]octan-3-one, 1,8-diazabicyclo(5,4,0)-undecene-7, and 1,5-diazabicyclo(4,3,0)-nonene-5 are more preferable.

[0028] From the viewpoint of achieving both the reactivity during thermosetting and the stability during storage when the epoxy resin composition is formed, the content of the low-molecular amine compound in the core (A) is preferably 0.001% by mass or more and 20% by mass or less, more preferably 0.003% by mass or more and 18% by mass or less, still more preferably 0.005% by mass or more and 16% by mass or less, even more preferably 0.008% by mass or more and 14% by mass or less, and particularly preferably 0.01% by mass or more and 12% by mass or less, based on the total mass of the core (A). From the same viewpoint as above, the content of the amine compound (a) in the core (A) is preferably 0.001% by mass or more and 20% by mass or less, more preferably 0.003% by mass or more and 18% by mass or less, still more preferably 0.005% by mass or more and 16% by mass or less, even more preferably 0.008% by mass or more and 14% by mass or less, and particularly preferably 0.01% by mass or more and 12% by mass or less, based on the total mass of the core (A).

[0029] The amine adduct compound is preferably a compound obtained by the reaction of an epoxy resin and a low molecular weight amine compound from the viewpoint of mechanical strength. As the epoxy resin, bisphenol A type epoxy resin and bisphenol F type epoxy resin are preferable from the viewpoint of toughness. As the low molecular weight amine compound, among the above-mentioned low molecular weight amine compounds, imidazole compounds, compounds having at least one primary amino group and / or secondary amino group but no tertiary amino group, and compounds having at least one tertiary amino group and at least one active hydrogen group are more preferable from the viewpoint of imparting excellent reactivity with the epoxy resin to the obtained amine adduct compound.

[0030] The low molecular weight amine compound contained in the core (A) may be a diverted unreacted low molecular weight amine compound when obtaining an amine adduct compound by reacting any one or more of a carboxylic acid compound, a sulfonic acid compound, a urea compound, an isocyanate compound, and an epoxy resin with the above-mentioned low molecular weight amine compound.

[0031] The core (A) can also contain components other than nitrogen-containing compounds and is not limited to the following. For example, phenolic curing agents, acid anhydride curing agents, catalyst-type curing agents, etc. can be mentioned.

[0032] Examples of the phenolic curing agent include, but are not limited to, phenolic novolak resin, cresol novolak resin, phenol aralkyl resin, cresol aralkyl resin, naphthol aralkyl resin, biphenyl-modified phenol resin, biphenyl-modified phenol aralkyl resin, dicyclopentadiene-modified phenol resin, aminotriazine-modified phenol resin, naphthol novolak resin, naphthol-phenol co-condensed novolak resin, naphthol-cresol co-condensed novolak resin, allyl acrylic phenol resin, etc.

[0033] Examples of the acid anhydride curing agent include, but are not limited to, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, etc.

[0034] Examples of the catalyst-type curing agent include, but are not limited to, cationic thermosetting catalysts, BF3-amine complexes, etc.

[0035] From the viewpoint of storage stability, it is preferable that the core (A) is solid at 25 °C and 1013 hPa. Thereby, when obtaining an epoxy resin composition by mixing with other components, even if the layer (B) is damaged, the components of the core (A) can be suppressed from eluting out of the layer (B), and the storage stability tends to be maintained.

[0036] The particle size D at the 50% cumulative undersize fraction of the core (A) 50 is preferably more than 0.3 μm and 12 μm or less. For the D of the core (A) 50 being larger than 0.3 μm can further prevent aggregation of the cores, make the formation of the layer (B) easier, and tend to further improve the storage stability when made into an epoxy resin composition. For the D of the core (A) 50 being 12 μm or less can prevent the formation of large-particle aggregates when blending a diluent, filler, pigment, dye, flow regulator, thickener, reinforcing agent, release agent, wetting agent, stabilizer, flame retardant, surfactant, organic solvent, conductive fine particles, crystalline alcohol, other resins, etc. when obtaining a desired epoxy resin composition, and tend to obtain sufficient long-term reliability of the cured product. For the D of the core (A) 50 is preferably larger than 0.3 μm as the lower limit value, more preferably 0.4 μm or more, and even more preferably 0.5 μm or more. As the upper limit value, 12 μm or less is preferable, 10 μm or less is more preferable, and 9 μm or less is even more preferable.

[0037] The D of the core (A) 50It means the average particle diameter defined by the median diameter. More specifically, it refers to the Stokes diameter measured by the laser diffraction / light scattering method using a particle size distribution analyzer (manufactured by Horiba, Ltd., "HORIBA LA-920").

[0038] The D of the core (A) 50 As a method for controlling the D within the above-described numerical range, although not limited to the following, for example, a method of performing precise control in the pulverization process of the massive core material, a method of performing a coarse pulverization process and a fine pulverization process as the pulverization process of the massive core material, and further using a precise classification device to obtain the desired D 50 by classification, a method of spray-drying a solution in which the massive core material is dissolved in a solvent, etc. can be mentioned. As the device used for pulverization, for example, a ball mill, an attritor, a bead mill, a jet mill, etc. can be adopted as needed, but it is preferable to use an impact pulverization device. Examples of the impact pulverization device include jet mills such as a rotary fluidized bed powder collision type jet mill and a powder collision type counter jet mill. A jet mill is a device that atomizes solid materials by colliding them with each other by a high-speed jet flow using air or the like as a medium. As a method of performing precise control in the pulverization process, methods of controlling the temperature, humidity, pulverization amount per unit time, etc. during pulverization can be mentioned. As a method of obtaining the desired D 50 by classification using a precise classification device after the pulverization process, for example, after pulverization, a predetermined D 50In order to obtain the powder or granule, a method of classification using a sieve (for example, a standard sieve such as 325 mesh or 250 mesh) or a classifier, or a method of classification by wind power according to the specific gravity of the particles can be mentioned. The classifier used can be a wet classifier or a dry classifier, but a dry classifier is generally preferred. Examples of such classifiers include "Elbow Jet" manufactured by Nittetsu Mining Co., Ltd., "Fine Sharp Separator" manufactured by Hosokawa Micron Corporation, "Variable Impactor" manufactured by Sankyo Denki Co., Ltd., "Spedic Classifier" manufactured by Seishin Enterprise Co., Ltd., "Donaserec" manufactured by Nippon Donaldson Co., Ltd., "YM Microcassette" manufactured by Yaskawa Shoji Co., Ltd., "Turbo Classifier" manufactured by Nisshin Engineering Co., Ltd., and various other air separators, micron separators, Microbrex, Accucut, and other dry classification devices, but are not limited thereto.

[0039] As a method for directly granulating the particles constituting the core, instead of pulverizing, there is a method for spray-drying a solution in which a lump of core material is dissolved in a solvent. Specifically, there is a method for uniformly dissolving the core material in an appropriate organic solvent, spraying the solution as fine droplets, and then drying with hot air or the like. In this case, a typical spray dryer can be used as the drying device. As a method for granulating the core particles, the core material is uniformly dissolved in a suitable organic solvent, and then, while vigorously stirring the homogeneous solution, a poor solvent for the nitrogen-containing compound constituting the core (A) is added to precipitate the core (A) in the form of fine particles. Next, the precipitated particles are separated by filtration, and the solvent is then dried and removed at a low temperature below the melting point of the core (A). D of the core (A) in particle state 50 As a method for adjusting the amount of 50 By mixing multiple particles with different D 50 For example, in the case of a large-particle-size core (A) that is difficult to crush or classify, a separate small-particle-size core (A) can be added and mixed to adjust the D 50 It is also possible to use a curing agent having a content within the above range. The curing agent thus obtained may be further classified as necessary. Examples of the mixer used for the purpose of mixing such powders include a container rotation type mixer that rotates the container body containing the powders to be mixed, a container fixed type mixer that does not rotate the container body containing the powders and performs mixing by mechanical stirring or air flow stirring, and a composite type mixer that rotates the container containing the powders and uses other external forces for mixing.

[0040] The core (A) is D 50 The particle size D of the cumulative undersize fraction of 99% with respect to D 99 The ratio (hereinafter, may be simply referred to as "D 99 / D 50 "), represented by the particle size distribution, is preferably 8.0 or less, more preferably 7.0 or less, still more preferably 6.0 or less, and particularly preferably 5.5 or less from the viewpoint of preventing aggregation of particles. D 99 / D 50 When D / D is 8.0 or less, there are few coarse particles in the powder particles of the core (A), the generation of aggregates is suppressed, and the physical properties of the cured product obtained by curing this as an epoxy resin composition tend to be prevented from being impaired. D 99 / D 50 The smaller the value of D / D, the sharper the particle size distribution of the core (A), and when it is made into an epoxy resin composition, it tends to be easy to obtain a homogeneous cured product and good curing performance. D 99 / D 50 is preferably 1.0 or more. When D / D is 1.0 or more, there is a tendency to suppress the formation of many gaps between the core (A) particles. D 99 / D 50 is more preferably 1.2 or more, still more preferably 1.5 or more, still more preferably 1.7 or more, and particularly preferably 2.0 or more. 99 / D 50 The particle size D of the cumulative undersize fraction of 99% 99It means the average particle diameter defined by the median diameter. More specifically, it refers to the Stokes diameter measured by the laser diffraction and light scattering method using a particle size distribution analyzer (manufactured by Horiba, Ltd., "HORIBA LA-920"). The D of the core (A) 99 / D 50 As a method for controlling the / D to the numerical range described above, the conditions of the method for controlling the aforementioned D 50 are adjusted so as to obtain the desired D 99 / D 50 It can be mentioned that the adjustment is made so that it becomes

[0041] In one embodiment, the core (A) has a specific surface area value Y (m 2 / g) multiplied by the particle diameter D 50 (μm) of the 50% sieve residue integration fraction may be 3.0 or more and 9.0 or less. When the above value is 3.0 or more, there is a tendency to suppress the aggregation of the core (A) particles, and when the above value is 9.0 or less, there is a tendency for the formation of the layer (B) to be facilitated. From the viewpoint of suppressing the aggregation of the core (A) particles, the above value may be 3.5 or more, and may be 4.0 or more. From the viewpoint of facilitating the formation of the layer (B), the above value may be 8.6 or less, and may be 8.3 or less. The specific surface area value Y (m 2 / g) of the core (A) can be measured based on the method described in the examples.

[0042] In one embodiment, the core (A) has a specific surface area value Y (m 2 / g) multiplied by the particle diameter D 50 (μm) may be more than 9.0 and 18.0 or less. When the above value is more than 9.0, there is a tendency to improve the reactivity, and when the above value is 18.0 or less, there is a tendency for a layer (B) having sufficient stability to be formed. From such a viewpoint, the above value may be 17.0 or less, and may be 16.5 or less.

[0043] As a method for adjusting the value obtained by multiplying the specific surface area value Y (m 2 / g) by the particle diameter D 50 (μm) within the range of 3.0 to 18.0, for example, the aforementioned D50 Examples include a method of adjusting the conditions of a method for controlling [a certain element], and a method of modifying the surface of the core (A). Examples of the method of modifying the surface include mechanically rounding particles, hot air treatment, etc. In this case, the above value tends to decrease. On the other hand, by appropriately setting the above-mentioned grinding device, grinding conditions, classification device, classification conditions, etc., the above value can also be increased.

[0044] [Layer (B)] The layer (B) is not particularly limited as long as it has the desired dyeability. Examples include a layer containing a synthetic resin or an inorganic oxide. Among these, it is preferable to contain a synthetic resin from the viewpoints of stability during storage and ease of destruction during heating.

[0045] The synthetic resin used for the layer (B) is not limited to the following. Examples include epoxy resins, phenolic resins, polyester resins, polyethylene resins, nylon resins, polystyrene resins, urethane resins, etc. Among these, from the viewpoint of the balance between the stability of the layer (B) and the destructibility during heating, epoxy resins, phenolic resins, and urethane resins are preferable.

[0046] The epoxy resin used for the layer (B) is not limited to the following. Examples include epoxy resins having two or more epoxy groups, resins produced by the reaction of an epoxy resin having two or more epoxy groups with a compound having two or more active hydrogens, reaction products of a compound having two or more epoxy groups with a compound having one active hydrogen and a carbon-carbon double bond, etc. Among these, from the viewpoint of stability, resins produced by the reaction of a compound having two or more epoxy groups with a compound having two or more active hydrogens are preferable, and particularly, reaction products of an amine-based curing agent and an epoxy resin having two or more epoxy groups are more preferable. Examples of the epoxy resin include the aforementioned epoxy resins, and examples of the amine-based curing agent include the nitrogen-containing compounds used for the core (A).

[0047] Examples of phenolic resins include, but are not limited to, phenol-formaldehyde polycondensates, cresol-formaldehyde polycondensates, resorcinol-formaldehyde polycondensates, bisphenol A-formaldehyde polycondensates, polyethylene polyamine-modified phenol-formaldehyde polycondensates, and the like.

[0048] Examples of polyester resins include, but are not limited to, ethylene glycol-terephthalic acid-polypropylene glycol polycondensates, ethylene glycol-butylene glycol-terephthalic acid polycondensates, terephthalic acid-ethylene glycol-polyethylene glycol polycondensates, and the like.

[0049] Examples of polyethylene resins include, but are not limited to, ethylene-propylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, ethylene-vinyl acetate-acrylic acid copolymers, and the like.

[0050] Examples of nylon resins include, but are not limited to, adipic acid-hexamethylene diamine polycondensates, sebacic acid-hexamethylene diamine polycondensates, p-phenylenediamine-terephthalic acid polycondensates, and the like.

[0051] Examples of polystyrene resins include, but are not limited to, styrene-butadiene copolymers, styrene-butadiene-acrylonitrile copolymers, acrylonitrile-styrene-divinylbenzene copolymers, styrene-propenyl alcohol copolymers, and the like.

[0052] Examples of the urethane resin include, but are not limited to, isocyanate monomers such as butyl isocyanate, cyclohexyl isocyanate, octadecyl isocyanate, phenyl isocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolidine diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, etc., or condensates or polymers thereof, and polycondensates of these with monoalcohols or polyhydric alcohols. Among these, urethane resins that are addition polymers of monoalcohols or polyhydric alcohols and monoisocyanates or polyisocyanates are preferred.

[0053] Examples of the inorganic oxide include, but are not limited to, boron compounds such as boron oxide and boric acid esters, silicon dioxide, calcium oxide, etc. Among these, boron oxide is preferred from the viewpoints of the stability of the film constituting the shell and the ease of destruction during heating.

[0054] Further, from the viewpoint of the balance between storage stability and curability when the epoxy resin composition of the present embodiment is used, layer (B) preferably contains a reaction product of two or more selected from the group consisting of isocyanate compounds, active hydrogen compounds, nitrogen-containing compounds, and epoxy resins.

[0055] As the isocyanate compound, nitrogen-containing compound, and epoxy resin, the compounds described above for core (A) can be used.

[0056] Examples of the active hydrogen compound include, but are not limited to, water, compounds having at least one primary amino group and / or secondary amino group, compounds having at least one hydroxyl group, etc. These active hydrogen compounds may be used alone or in combination of two or more.

[0057] Examples of the compound having at least one primary amino group and / or secondary amino group include, but are not limited to, aliphatic amines, alicyclic amines, aromatic amines and the like. Examples of the aliphatic amine include, but are not limited to, alkylamines such as methylamine, ethylamine, propylamine, butylamine and dibutylamine; alkylenediamines such as ethylenediamine, propylenediamine, butylenediamine and hexamethylenediamine; polyalkylenepolyamines such as diethylenetriamine, triethylenetetramine and tetraethylenepentamine; polyoxyalkylenepolyamines such as polyoxypropylenediamine and polyoxyethylenediamine. Examples of the alicyclic amine include, but are not limited to, cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine and isophoronediamine. Examples of the aromatic amine include, but are not limited to, aniline, toluidine, benzylamine, naphthylamine, diaminodiphenylmethane and diaminodiphenylsulfone.

[0058] Examples of the compound having at least one hydroxyl group include alcohol compounds, phenol compounds and the like. Examples of the alcohol compound include, but are not limited to, monohydric alcohols such as methyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, dodecyl alcohol, stearyl alcohol, eicosyl alcohol, allyl alcohol, crotyl alcohol, propargyl alcohol, cyclopentanol, cyclohexanol, benzyl alcohol, cinnamyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and diethylene glycol monobutyl; polyhydric alcohols such as ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3 - butanediol, 1,4 - butanediol, hydrogenated bisphenol A, neopentyl glycol, glycerin, trimethylolpropane, and pentaerythritol; and polyhydric alcohols such as compounds having two or more secondary hydroxyl groups in one molecule, which are obtained by reacting a compound having at least one epoxy group with a compound having at least one hydroxyl group, carboxyl group, primary amino group, secondary amino group, or thiol group, etc. These alcohol compounds may be any of primary alcohol, secondary alcohol, and tertiary alcohol. Examples of the phenol compound include, but are not limited to, monophenols such as phenol, cresol, xylenol, carvacrol, thymol, and naphthol; and polyhydric phenols such as catechol, resorcinol, hydroquinone, bisphenol A, bisphenol F, pyrogallol, phloroglucin, 2 - (dimethylaminomethyl)phenol, and 2,4,6 - tris(dimethylaminomethyl)phenol, etc. From the viewpoints of latency and solvent resistance, the compound having at least one hydroxyl group is preferably a polyhydric alcohol or a polyhydric phenol, and more preferably a polyhydric alcohol.

[0059] The reaction conditions for preparing two or more reaction products selected from the group consisting of an isocyanate compound, an active hydrogen compound, a nitrogen-containing compound, and an epoxy resin, which are contained in layer (B) as described above, are not particularly limited, but are usually in the temperature range of -10°C to 150°C and the reaction time is 10 minutes to 12 hours.

[0060] When an isocyanate compound and an active hydrogen compound are used to prepare the reaction product contained in layer (B), the mixing ratio is preferably in the range of (isocyanate groups in the isocyanate compound):(active hydrogen in the active hydrogen compound) (equivalent ratio) of 1:0.1 to 1:1000.

[0061] The reaction can be carried out in a predetermined dispersion medium if necessary. Examples of the dispersion medium include solvents, plasticizers, resins, etc. Examples of the solvent include, but are not limited to, hydrocarbons such as benzene, toluene, xylene, cyclohexane, mineral spirit, and naphtha; ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone; esters such as ethyl acetate, n-butyl acetate, and propylene glycol monomethyl ethyl ether acetate; alcohols such as methanol, isopropanol, n-butanol, butyl cellosolve, and butyl carbitol; and water. Examples of the plasticizer include, but are not limited to, phthalic acid diester plasticizers such as dibutyl phthalate and di(2-ethylhexyl) phthalate; aliphatic dibasic acid ester plasticizers such as di(2-ethylhexyl) adipate; phosphoric acid triester plasticizers such as tricresyl phosphate; and glycol ester plasticizers such as polyethylene glycol ester. Examples of the resins include, but are not limited to, silicone resins, epoxy resins, and phenolic resins. These may be used alone or in combination of two or more.

[0062] Among these, the reaction between the epoxy resin and the nitrogen-containing compound is usually carried out at a temperature range of -10°C to 150°C, preferably 0°C to 100°C, for a reaction time of 1 hour to 168 hours, preferably 2 hours to 72 hours. Further, as the dispersion medium, preferably a solvent and a plasticizer are used.

[0063] In addition, the mass percentage of the above-mentioned reaction product in layer (B) is usually 1% by mass or more, preferably 50% by mass or more, and may be 100% by mass.

[0064] Examples of the method for forming layer (B) include the following methods (1) to (3). (1): A method in which core (A) particles and a material for forming layer (B) (layer (B) forming material) are dissolved and dispersed in a solvent as a dispersion medium, and then the solubility of the layer (B) forming material in the dispersion medium is decreased to deposit it on the surface of the core (A) particles. (2): A method in which core (A) particles are dispersed in a dispersion medium, and the above-mentioned layer (B) forming material is added to this dispersion medium to deposit it on the core (A) particles. (3): A method in which a layer (B) forming material is added to a dispersion medium, and layer (B) is generated there using the surface of the core (A) particles as the reaction site. Here, the methods (2) and (3) are preferable because the reaction and the coating can be carried out simultaneously.

[0065] In addition, in the methods (1) to (3) above, examples of the dispersion medium include a solvent, a plasticizer, a resin, etc. Further, as the solvent, plasticizer, and resin, the same ones as those used in the reaction for preparing two or more reaction products selected from the group consisting of an isocyanate compound, an active hydrogen compound, a nitrogen-containing compound, and an epoxy resin, which are contained in the aforementioned layer (B), can be used.

[0066] After forming layer (B) by the methods (2) and (3), the method for separating the epoxy resin curing agent from the dispersion medium is not particularly limited, and examples include a method of removing the dispersion medium and the raw materials for forming the unreacted layer (B) by filtration. After removing the dispersion medium, it is preferable to wash the epoxy resin curing agent. The washing method is not particularly limited. However, when separation by filtration is performed, the residue can be washed with a solvent that does not dissolve it. By drying after filtration and washing, the epoxy resin curing agent can be obtained in a powdery form. The drying method is not particularly limited, but it is preferably dried at a temperature equal to or lower than the melting point or softening point of core (A) and layer (B). For example, drying under reduced pressure can be mentioned. By making it powdery, the compounding operation of the epoxy resin curing agent and the epoxy resin can be easily performed. Further, when an epoxy resin is used as the dispersion medium, it is preferable because an epoxy resin composition integrated with the epoxy resin can be obtained simultaneously with the formation of layer (B).

[0067] The formation reaction of layer (B) is carried out in a temperature range of -10°C to 150°C, preferably 0°C to 100°C, and a reaction time of 10 minutes to 72 hours, preferably 30 minutes to 24 hours. After the formation reaction of layer (B) is completed, it is preferable to leave the epoxy resin curing agent standing in an environment of 5 to 12°C or lower for 8 hours or more (through a standing step). When passing through the standing step, layer (B) tends to have the desired dyeability. In addition, in the standing step in this embodiment, it is preferable that the difference between the measured temperature and the set temperature is small. For example, the lowest temperature T L and the highest temperature T H The difference between them is preferably 4°C or less. In this case, layer (B) having the desired dyeability is more easily obtained. As described above, the formation reaction can be carried out using a dispersion medium, and an operation of removing the dispersion medium may be performed between the formation reaction and the standing step. Further, the set temperature in the standing step may be lower than the temperature conditions of the formation reaction. As an example, the set temperature in the standing step may be set 40°C or more lower than the reaction temperature in the formation reaction, or may be set 45°C or more lower. Furthermore, the formation reaction and the standing step may be carried out in the same system or in different systems.

[0068] The presence of layer (B) can be confirmed by TEM observation described later. The thickness of layer (B) is preferably from 1 nm to 1000 nm, more preferably from 2 nm to 800 nm, still more preferably from 3 nm to 600 nm, and even more preferably from 4 nm to 400 nm. When the thickness of layer (B) is 1 nm or more, sufficient stability tends to be imparted. Also, when layer (B) is 1000 nm or less, sufficient reactivity tends to be imparted. Here, the thickness of layer (B) is defined as the distance between the points where the line segment connecting an arbitrary point on the boundary corresponding to the luminance γ of the boundary between layer (B) and core (A) and the point corresponding to the luminance β of the outermost part of layer (B) from this point is the shortest. Also, the thickness of layer (B) may vary depending on the location, and in that case, the width of the thickness is preferably in the range of 1 nm to 1000 nm, more preferably in the range of 2 nm to 800 nm, still more preferably 3 nm to 600 nm, and even more preferably 4 nm to 400 nm.

[0069] 〔Dyeability of layer (B)〕 When the epoxy resin curing agent of the present embodiment is stained with ruthenium tetroxide and osmium tetroxide and then observed by TEM to obtain a luminance graph by image processing, the interior of the layer (B) has a region having a luminance α, and the luminance α is higher than the luminance β of the outermost part of the layer (B) and the luminance γ of the boundary between the layer (B) and the core (A). That the interior of layer (B) has the above region can be confirmed based on the method described in the examples below. When the epoxy resin curing agent is the masterbatch type epoxy resin curing agent composition described later, if necessary, after adding a dispersion medium, separating the epoxy resin and the curing agent component with a centrifuge, and collecting and drying the curing agent component, a single epoxy resin curing agent can also be obtained. Examples of the dispersion medium include solvents, plasticizers, resins, etc., and it can be selected from commercially available dispersion media according to the solubility of layer (B).

[0070] In this specification, when there is a layer with different stainability from both the region of the epoxy resin composition for staining and the core (A) between them in the above-described TEM observation, this layer is defined as layer (B). Whether the stainability is the same or different can be confirmed by visually observing the TEM image. Also, the difference in stainability can be confirmed by the fact that the brightness from the region of the epoxy resin composition for staining to the core (A) is not monotonic in the above-described brightness graph.

[0071] Layer (B) may be a single layer or multiple layers.

[0072] In this specification, the outermost part of layer (B) is defined as the location with the lowest brightness near the boundary between layer (B) and the region of the epoxy resin composition for staining, and the boundary between the core (A) and layer (B) is defined as the location with the lowest brightness near the boundary between the core (A) and layer (B). When layer (B) is a multiple layer, at least one layer (B) may have the desired stainability, and it is preferable that all layers (B) have the desired stainability. The epoxy resin curing agent of this embodiment may have a circularity of 0.90 or more, 0.93 or more, 0.95 or more, or 0.98 or more. Circularity represents the degree of proximity to a perfect sphere, and the circularity of a perfect sphere is 1. Also, the surface of the epoxy resin curing agent (the surface of layer (B)) may be smooth or may have irregularities. When the surface of layer (B) is smooth, as a result of TEM image analysis, an image in which the boundary between layer (B) and the region of the epoxy resin composition for staining appears linear or curved can be observed (see FIGS. 1 and 3 described later). On the other hand, when irregularities are seen on the surface of layer (B), as a result of TEM image analysis, an image in which the boundary between layer (B) and the region of the epoxy resin composition for staining appears wavy or ridged can be observed (see FIG. 5 described later). Also, in this embodiment, whether the brightness of the location with the highest brightness in layer (B) is higher than the maximum value of the brightness of the core (A) as shown in FIG. 2 described later, or whether the brightness of the location with the highest brightness in layer (B) is lower than the maximum value of the brightness of the core (A) as shown in FIG. 4 described later, can be included. Any aspect can be preferably used as long as a brightness α higher than brightness β and brightness γ is observed.

[0073] As a result of intensive studies by the present inventors, after the formation reaction of layer (B) is completed, by subjecting the epoxy resin curing agent to the above-described standing step, the epoxy resin curing agent of the present embodiment having a region in layer (B) where the dyeability with ruthenium tetroxide or osmium tetroxide by the above-described staining method is significantly reduced (hereinafter, also referred to as a low-dyeability epoxy resin curing agent) can be obtained. This low-dyeability epoxy resin curing agent has improved resistance to low-molecular epoxy resin compounds, solvents, and low-molecular acrylic resins while maintaining reactivity as compared with an epoxy resin curing agent having a coating layer that can be easily dyed as a whole with ruthenium tetroxide or osmium tetroxide (hereinafter, also referred to as a high-dyeability epoxy resin curing agent), and excellent storage stability can be imparted even when applied to an epoxy resin composition containing these. In addition, an epoxy resin composition containing a filler was prepared using a low-dyeability epoxy resin curing agent, and after curing this, as a result of observing the appearance of the cured product in a minute region, a cured product having an excellent appearance in which the filler is more uniformly dispersed was obtained as compared with a high-dyeability epoxy resin curing agent.

[0074] Regarding the mechanism by which the low-dyeability epoxy resin curing agent of the present embodiment improves resistance to low-molecular epoxy compounds, solvents, and low-molecular acrylic compounds while maintaining reactivity, although it is not intended to be limiting, it is presumed as follows. The layer (B) of the low-dyeability epoxy resin exhibits low dyeability because the crosslink density is high, making it difficult for ruthenium tetroxide or osmium tetroxide to penetrate into the layer during dyeing. That is, due to the presence of crosslinking points and molecular chains in a high-density state, penetration of low-molecular epoxy compounds, solvents, and low-molecular acrylic compounds into layer (B) is suppressed, and dissolution of core (A) by these low-molecular compounds is prevented, showing excellent storage stability. On the other hand, in the high-temperature range during the reaction, the reactivity is maintained because the influence on strength improvement is very small.

[0075] An epoxy resin composition containing a filler was prepared using the low-staining epoxy resin curing agent of the present embodiment. After curing this, regarding the mechanism by which a cured product having an excellent appearance in which the filler is more uniformly dispersed is obtained when observing the appearance of the cured product in a minute region, although it is not intended to be limiting, it is presumed as follows. Since the layer (B) of the low-staining epoxy resin curing agent has crosslinking points and molecular chains in a high-density state, the surface hardness is high. As a result, the contact area when colliding with the filler during compounding becomes small, so the probability of aggregation of the curing agent and the filler is reduced, and the state in which the filler is uniformly dispersed can be maintained until the curing stage.

[0076] As described above, when evaluating the staining property of the epoxy resin curing agent of the present embodiment, a stained cured product is obtained. That is, the method for producing a stained cured product of the present embodiment includes a step (S1) of electron-staining an epoxy resin curing agent having a core (A) and a layer (B) covering the core (A) with ruthenium tetroxide, a step (S2) of obtaining a cured product of the composition containing the epoxy resin curing agent that has undergone the step (S1), and a step (S3) of electron-staining a section of the cured product with osmium tetroxide. The epoxy resin curing agent in the step (S1) corresponds to the epoxy resin curing agent of the present embodiment. The steps (S2) and (S3) can be carried out in the same manner as the method for evaluating the staining property of the layer (B) described above. By subjecting the stained cured product to the above-described TEM observation and image processing, typically, it is confirmed that the inside of the layer (B) has a region having a higher luminance than the luminance of the outermost part and the luminance of the above boundary.

[0077] 〔Epoxy resin composition〕 The epoxy resin curing agent of the present embodiment can be an epoxy resin composition containing an epoxy resin (C). The above-described epoxy resin composition can also be used as a masterbatch-type epoxy resin curing agent composition. That is, the masterbatch-type epoxy resin curing agent composition containing the epoxy resin curing agent of the present embodiment is also included in the present embodiment.

[0078] 〔Epoxy resin (C)〕 As the epoxy resin (C), the aforementioned epoxy resins can be used. The epoxy resin (C) may be used alone or in combination of two or more.

[0079] From the viewpoint of imparting sufficient reactivity, suppressing aggregation between the epoxy resin curing agents, and imparting sufficient mechanical strength to the cured product, the mass ratio of the epoxy resin curing agent to the epoxy resin (C) in this embodiment (epoxy resin curing agent: epoxy resin) is preferably 0.1:100 to 1000:100, more preferably 0.5:100 to 500:100, and particularly preferably 1:100 to 200:100. Further, when the above-mentioned epoxy resin composition is used as a masterbatch type curing agent, from the viewpoint of imparting sufficient reactivity as a curing agent and suppressing aggregation between the curing agents, the mass ratio of the epoxy resin curing agent to the epoxy resin (C) in this embodiment (epoxy resin curing agent: epoxy resin) is preferably 0.1:100 to 1000:100, more preferably 1:100 to 500:100, further preferably 5:100 to 300:100, even more preferably 10:100 to 200:100, and particularly preferably 20:100 to 150:100.

[0080] The epoxy resin composition of this embodiment preferably contains a bisphenol type epoxy resin as the epoxy resin (C) from the viewpoints of handleability and heat resistance, and more preferably contains one or more of bisphenol A type epoxy resin and bisphenol F type epoxy resin from the viewpoint of imparting sufficient mechanical properties.

[0081] From the viewpoint of obtaining an epoxy resin composition having excellent electrical properties and an excellent balance between curability and storage stability, the total chlorine content contained in the epoxy resin (C) is preferably 2500 ppm or less, more preferably 2000 ppm or less, further preferably 1500 ppm or less, and particularly preferably 900 ppm or less. Also, from the viewpoint of achieving a predetermined technical significance, the total chlorine content contained in the (A) epoxy resin is preferably 0.01 ppm or more, more preferably 0.05 ppm or more, further preferably 0.1 ppm or more, and particularly preferably 0.5 ppm or more.

[0082] Here, the total chlorine content contained in the epoxy resin (C) indicates the total amount of organic chlorine and inorganic chlorine contained in the epoxy resin (C), and is a value based on mass with respect to the epoxy resin (C). The total chlorine content of the epoxy resin (C) is measured by the following method. The epoxy resin (C) is washed with xylene, and washing and filtration are repeated until there is no epoxy resin left in the xylene as the washing liquid. Next, the filtrate is distilled off under reduced pressure at 100°C or lower to obtain an epoxy resin. 1 to 10 g of the obtained epoxy resin sample is precisely weighed so that the titration amount becomes 3 to 7 mL, dissolved in 25 mL of ethylene glycol monobutyl ether, 25 mL of a propylene glycol solution of 1N KOH is added thereto, boiled for 20 minutes, and then calculated from the titration amount titrated with an aqueous silver nitrate solution.

[0083] Here, among the total chlorine, the chlorine contained in the 1,2-chlorohydrin group is generally called hydrolyzable chlorine. The amount of hydrolyzable chlorine in the epoxy resin (C) is preferably 100 ppm or less, more preferably 50 ppm or less, still more preferably 0.01 ppm or more and 20 ppm or less, and even more preferably 0.05 ppm or more and 10 ppm or less. When the amount of hydrolyzable chlorine in the epoxy resin (C) is 100 ppm or less, it is advantageous from the viewpoint of achieving both high curability and storage stability in the epoxy resin composition of the present embodiment, and the cured product of the epoxy resin composition of the present embodiment tends to exhibit excellent electrical properties.

[0084] Here, the hydrolyzable chlorine in the epoxy resin (C) is measured by the following method. 3 g of the sample is dissolved in 50 mL of toluene, 20 mL of a 0.1N KOH methanol solution is added thereto, boiled for 15 minutes, and then calculated from the titration amount titrated with an aqueous silver nitrate solution.

[0085] [Alcohol compound (D) represented by formula (1)] The epoxy resin composition of this embodiment can further contain an alcohol compound (D) represented by the following formula (1) (hereinafter also referred to as "component (D)"). By containing component (D), the epoxy resin composition of this embodiment tends to improve its low-temperature curability while maintaining its storage stability.

[0086]

Chemical formula

[0087] In formula (1), X1 represents an alkylene group having 2 to 5 carbon atoms which may have a substituent R, and the substituents R and R1 to R5 each independently represent a hydrogen atom, an alkyl group, an unsaturated aliphatic group, an aromatic group, a substituent containing a hetero atom, or a halogen atom, where any one selected from R1 to R5 may be a condensed ring compound constituting the same ring. Examples of the substituent containing a hetero atom may be a substituent containing a halogen atom.

[0088] Examples of the alcohol compound represented by the above formula (1) include, but are not limited to, 3-phenoxy-1-propanol, 3-phenoxy-1,2-propanediol, 3-phenoxy-1,3-propanediol, 3-(ortho-tolyloxy)-1,2-propanediol, 3-(2-methoxyphenoxy)propane-1,2-diol, bisphenol A (3-hydroxypropyl) glycidyl ether, and bisphenol A (2,3-dihydroxypropyl) glycidyl ether. Bisphenol A (2,3-dihydroxypropyl) glycidyl ether is particularly preferred. These may be used alone or in combination of two or more.

[0089] When added to the epoxy resin composition of the present embodiment, the addition amount of component (D) is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, still more preferably 0.005% by mass or more, and particularly preferably 0.01% by mass or more, from the viewpoint of sufficiently exerting the effect of improving reactivity with respect to the entire epoxy resin composition. Further, from the viewpoint of suppressing deterioration of storage stability due to excessive addition, it is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2.5% by mass or less, and even more preferably 2% by mass or less.

[0090] Component (D) may be added during mixing with other components, may be generated in the system after mixing, or may be generated in the system when producing the core (A), the layer (B), and the epoxy resin (C).

[0091] 〔Other Additives〕 The epoxy resin composition of the present embodiment may further contain, if necessary, in addition to the above-described components, an epoxy resin curing agent other than the epoxy resin curing agent of the present embodiment, a low-molecular epoxy compound, a solvent, a low-molecular acrylic compound, an organic filler, an inorganic filler, a pigment, a dye, a flow regulator, a thickener, a release agent, a wetting agent, a flame retardant, a surfactant, resins other than epoxy resins, and the like.

[0092] Examples of the epoxy resin curing agent other than the epoxy resin curing agent of the present embodiment include nitrogen-containing compounds, phenolic curing agents, acid anhydride curing agents, and catalyst-type curing agents mentioned as components of the aforementioned core (A), and in addition, active ester-based curing agents, cyanate ester-based curing agents, thiol-based curing agents, and the like.

[0093] An active ester-based curing agent is one that functions as a curing agent for an epoxy resin and has an active ester in its molecule. When the epoxy resin composition of the present embodiment contains an active ester-based curing agent, since a hydroxyl group, which is a factor for increasing the dielectric loss tangent, is not generated in the epoxy resin composition due to the reaction between the active ester and the epoxy group, the dielectric loss tangent tends to be lowered. The active ester curing agent is not particularly limited, but from the viewpoint of ensuring the crosslinking density, a compound having two or more active ester groups in one molecule is preferable. Further, from the viewpoints such as heat resistance of the epoxy resin composition of the present embodiment, an active ester compound obtained by reacting a carboxylic acid compound and / or a thiocarboxylic acid compound with a hydroxy compound and / or a thiol compound is more preferable, and an active ester compound obtained by reacting a carboxylic acid compound with one or more selected from a phenol compound, a naphthol compound, and a thiol compound is even more preferable. And an aromatic compound having two or more active ester groups in one molecule, which is obtained by reacting a carboxylic acid compound with an aromatic compound having a phenolic hydroxyl group, is even more preferable. And an aromatic compound which is obtained by reacting a compound having at least two or more carboxylic acids in one molecule with an aromatic compound having a phenolic hydroxyl group, and which has two or more active ester groups in one molecule of the aromatic compound is even more preferable. Further, the active ester curing agent may be linear or multi-branched. Also, if the compound having at least two or more carboxylic acids in one molecule is a compound containing an aliphatic chain, the compatibility with the epoxy resin can be increased, and if it is a compound having an aromatic ring, the heat resistance tends to be increased.

[0094] Here, examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid and the like. In particular, from the viewpoint of the heat resistance of the epoxy resin composition of the present embodiment, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, and terephthalic acid are preferable, and isophthalic acid and terephthalic acid are more preferable. Examples of the thiocarboxylic acid compound include thioacetic acid, thiobenzoic acid and the like, but are not particularly limited thereto. Examples of the phenolic compound or naphthol compound include, but are not limited to, hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadienyldiphenol, phenol novolac, and the like.Among these, from the viewpoints of the heat resistance of the epoxy resin composition of the present embodiment and the solubility in epoxy resins and solvents, bisphenol A, bisphenol F, bisphenol S, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, benzenetriol, dicyclopentadienyl diphenol, and phenol novolak are preferable, catechol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, benzenetriol, dicyclopentadienyl diphenol, and phenol novolak are more preferable, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, dicyclopentadienyl diphenol, and phenol novolak are further preferable, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, dicyclopentadienyl diphenol, and phenol novolak are even more preferable, dicyclopentadienyl diphenol and phenol novolak are still more preferable, and dicyclopentadienyl diphenol is particularly preferable. Examples of the thiol compound include, but are not particularly limited to, benzenedithiol, triazine dithiol, and the like.

[0095] As the active ester compound which is an active ester-based curing agent, the active ester compounds disclosed in JP-A-2004-277460 and JP-A-2013-40270 may be used, or commercially available active ester compounds may also be used. Examples of commercially available active ester compounds include, for example, products manufactured by DIC Corporation, trade names: EXB9451, EXB9460, EXB9460S, HPC-8000-65T (an active ester compound containing a dicyclopentadiene type diphenol structure), EXB9416-70BK (an active ester compound containing a naphthalene structure), EXB9050L-62M (a phosphorus atom-containing active ester compound); products manufactured by Mitsubishi Chemical Corporation, trade names: DC808 (an active ester compound containing an acetylated product of phenol novolak), YLH1026 (an active ester compound containing a benzoylated product of phenol novolak), etc. These may be used alone or in combination of two or more kinds.

[0096] The cyanate ester-based curing agent functions as a curing agent for an epoxy resin and has a cyanato group in the molecule. Since the epoxy resin composition of the present embodiment contains a cyanate ester-based curing agent as other additives, an oxazoline ring or an oxazolidinone ring is formed by reaction with an epoxy group to impart flexibility to the epoxy resin composition, and at the same time, a triazine skeleton formation due to trimerization of the cyanato group occurs, so that the warpage can be reduced and particularly the heat resistance can be improved. Further, since a hydroxyl group is hardly generated during the reaction, the dielectric loss tangent can be kept low.

[0097] Examples of the cyanate ester curing agent include, but are not limited to, for example, novolak type (phenol novolak type, alkylphenol novolak type, etc.) cyanate ester resins, dicyclopentadiene type cyanate ester resins, bisphenol type (bisphenol A type, bisphenol F type, bisphenol S type, etc.) cyanate ester resins, and prepolymers in which part of these is triazine-formed. Specific examples of the cyanate ester resin include, for example, bisphenol A dicyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidenebisphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanate phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanate phenyl-1-(methylethylidene))benzene, bis(4-cyanate phenyl)thioether, bis(4-cyanate phenyl)ether and other bifunctional cyanate resins, polyfunctional cyanate resins derived from phenol novolak, cresol novolak, dicyclopentadiene structure-containing phenol resins, etc., prepolymers in which part of these cyanate resins is triazine-formed, and the like. These may be used alone or in combination of two or more.

[0098] The thiol-based curing agent may be any compound that contains two or more thiol groups in one molecule, and is not limited to the following. For example, 3,3'-dithiobipropionic acid, trimethylolpropane tris(thioglycolate), pentaerythritol tetrakis(thioglycolate), ethylene glycol dithioglycolate, 1,4-bis(3-mercaptobutyryloxy)butane, tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), dipentaerythritol hexakis(3-mercaptopropionate), 1,3,4,6-tetrakis(2-mercaptoethyl)glycoluril, 4-butanedithiol, 1,6-hexanedithiol, 1,10-decanedithiol, etc. can be mentioned. From the viewpoint of impact resistance, 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate) are preferred, and from the viewpoint of low-temperature curability, pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate) are more preferred. These may be used alone or in combination of two or more.

[0099] In this specification, the low-molecular-weight epoxy compound excludes the compounds exemplified in the above epoxy resin (C), and is a compound having a viscosity at 25°C of 1 mPa·s or more and less than 3 Pa·s. The low-molecular-weight epoxy compound is sometimes called a reactive diluent.

[0100] Examples of the low molecular weight epoxy compounds include, but are not limited to, for example, epoxy compounds having no aromatic ring and epoxy compounds having an aromatic ring described below. Examples of the monofunctional epoxy compound having no aromatic ring include compounds such as n-butyl glycidyl ether, t-butyl glycidyl ether, allyl glycidyl ether, and 2-ethylhexyl glycidyl ether. Examples of the monofunctional epoxy compound having one or more aromatic rings include compounds such as styrene oxide, phenyl glycidyl ether, cresyl glycidyl ether, p-sec-butylphenyl glycidyl ether, t-butylphenyl glycidyl ether, and a compound with the trade name SY-OPG manufactured by Sakamoto Yakuhin Kogyo Co., Ltd. Examples of the difunctional epoxy compound having no aromatic ring include, for example, 1,4-cyclohexanedimethanol diglycidyl ether, 1,3-cyclohexanedimethanol diglycidyl ether, (3,4-epoxycyclohexyl)methyl-3,4-epoxycyclohexyl carboxylate, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, dicyclopentadiene dimethanol diglycidyl ether, vinylcyclohexene dioxide, a compound with the trade name YX-8000 manufactured by Mitsubishi Chemical Corporation, and a compound with the trade name SR-8EGS manufactured by Sakamoto Yakuhin Kogyo Co., Ltd. Examples of the difunctional epoxy compound having one or more aromatic rings include, for example, hexahydrophthalic acid diglycidyl ether, resorcinol diglycidyl ether, tert-butyl hydroquinone diglycidyl ether, diglycidyl ether of polyoxyalkylene bisphenol A, N,N-diglycidylaniline, and N,N-diglycidyl-o-toluidine. Examples of the trifunctional epoxy compound include, for example, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, and N,N-bis(2,3-epoxypropyl)-4-(2,3-epoxypropoxy)aniline.

[0101] Examples of the solvent include, but are not limited to, hydrocarbons such as toluene, xylene, cyclohexane, mineral spirit, and solvent naphtha; ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone; esters such as ethyl acetate, n-butyl acetate, and propylene glycol monomethyl ethyl ether acetate; alcohols such as isopropanol, n-butanol, butyl cellosolve, butyl carbitol, and 1-methoxy-2-propanol; amide solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0102] The low-molecular-weight acrylic compound means an acrylic compound having a molecular weight of 700 or less, and examples include, but are not limited to, compounds having (meth)acryloyl groups at both ends of a polyalkylene oxide, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polybutylene glycol di(meth)acrylate, trimethylolpropane type polyfunctional (meth)acrylate, pentaerythritol type polyfunctional (meth)acrylate, dipentaerythritol type polyfunctional (meth)acrylate, and epoxy (meth)acrylate.

[0103] The organic filler has a function as an impact modifier that can relieve the stress generated by impact. By containing the organic filler, the epoxy resin composition of the present embodiment can further improve the adhesiveness to various connecting members. In addition, it tends to suppress the generation and progression of fillet cracks. Examples of the organic filler include, but are not limited to, acrylic resin, silicone resin, butadiene rubber, polyester, polyurethane, polyvinyl butyral, polyarylate, polymethyl methacrylate, acrylic rubber, polystyrene, NBR, SBR, silicone-modified resin, and organic fine particles of copolymers containing these as components. From the perspective of improving adhesion, examples of the organic fine particles include (meth)acrylic acid alkyl-butadiene-styrene copolymers, (meth)acrylic acid alkyl-silicone copolymers, silicone-(meth)acrylic copolymers, composites of silicone and (meth)acrylic acid, composites of (meth)acrylic acid alkyl-butadiene-styrene and silicone, and composites of (meth)acrylic acid alkyl and silicone. In addition, as the organic fine particles, organic fine particles having a core-shell structure and different compositions in the core layer and the shell layer can also be used. Examples of the core-shell type organic fine particles include particles obtained by grafting an acrylic resin onto a silicone-acrylic rubber as the core, and particles obtained by grafting an acrylic resin onto an acrylic copolymer. These organic fillers may be used alone or in combination of two or more.

[0104] Since the inorganic filler can adjust the coefficient of thermal expansion of the epoxy resin composition of the present embodiment, containing the inorganic filler tends to contribute to improving the heat resistance and moisture resistance when the epoxy resin composition of the present embodiment is used as an underfill material. Examples of the inorganic filler include, but are not limited to, silicates such as talc, calcined clay, uncalcined clay, mica, and glass; oxides such as titanium oxide, aluminum oxide (alumina), fused silica (e.g., fused spherical silica and fused crushed silica), synthetic silica, and crystalline silica; carbonates such as calcium carbonate, magnesium carbonate, and hydrotalcite; hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; sulfates such as barium sulfate and calcium sulfate; sulfites such as calcium sulfite; borates such as zinc borate, barium metaborate, aluminum borate, calcium borate, and sodium borate; nitrides such as aluminum nitride, boron nitride, and silicon nitride. Among these, from the viewpoint of improving heat resistance, moisture resistance, and strength, fused silica, crystalline silica, and synthetic silica powder are preferable, and either aluminum oxide or boron nitride is also preferable. By using these, the coefficient of thermal expansion can be suppressed, and thus improvement in the thermal cycle test and the like can be expected. The shape of the inorganic filler is not particularly limited, and may be any form such as amorphous, spherical, and flaky, for example. These inorganic fillers may be used alone or in combination of two or more.

[0105] Examples of the pigment include, but are not limited to, kaolin, aluminum oxide trihydrate, aluminum hydroxide, chalk powder, gypsum, calcium carbonate, antimony trioxide, penton, silica, aerosol, lithopone, barite, titanium dioxide, and the like.

[0106] Examples of the dye include, but are not limited to, natural dyes such as plant-derived dyes such as madder and indigo, and mineral-derived dyes such as loess and red clay, synthetic dyes such as alizarin and indigo, and fluorescent dyes.

[0107] Examples of the flow regulator include, but are not limited to, organic silane compounds such as silane coupling agents; organic titanium compounds such as titanium tetraisopropoxide and titanium diisopropoxide bis(acetylacetonate); and organic zirconium compounds such as zirconium tetranormal butoxide and zirconium tetraacetylacetonate.

[0108] Examples of the thickener include, but are not limited to, animal-derived thickeners such as gelatin; plant-derived thickeners such as polysaccharides and cellulose; and chemically synthesized thickeners such as polyacrylic-based thickeners, modified polyacrylic-based thickeners, polyether-based thickeners, urethane-modified polyether-based thickeners, and carboxymethyl cellulose.

[0109] Examples of the release agent include, but are not limited to, fluorine-based release agents, silicone-based release agents, acrylic-based release agents composed of a copolymer of glycidyl (meth)acrylate and a linear alkyl (meth)acrylate having 16 to 22 carbon atoms, and the like.

[0110] Examples of the wetting agent include, but are not limited to, unsaturated polyester copolymer-based wetting agents having an acidic group, such as acrylic polyphosphate esters, and the like.

[0111] Examples of the flame retardant include, but are not limited to, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, halogen-based flame retardants such as chlorine compounds and bromine compounds, phosphorus-based flame retardants such as condensed phosphate esters, antimony-based flame retardants such as antimony trioxide and antimony pentoxide, inorganic oxides such as silica, and the like.

[0112] Examples of the surfactant include, but are not limited to, anionic surfactants such as alkylbenzene sulfonates and alkyl polyoxyethylene sulfates, cationic surfactants such as alkyl dimethyl ammonium salts, amphoteric surfactants such as alkyl dimethyl amine oxides and alkyl carboxy betaines, nonionic surfactants such as linear alcohols having 25 or more carbon atoms and fatty acid esters, and the like.

[0113] Examples of resins other than epoxy resins include, but are not limited to, silicone resins, phenolic resins, phenoxy resins, polyvinyl butyral resins, polyvinyl acetal resins, polyacrylic resins, polyimide resins, and elastomers having functional groups such as carboxyl groups, hydroxyl groups, vinyl groups, and amino groups.

[0114] [Method for Producing Epoxy Resin Composition] The method for producing the epoxy resin composition of the present embodiment includes a step of obtaining a mixture of the epoxy resin curing agent having the core (A) and the layer (B) of the present embodiment described above and the epoxy resin (C). The step of obtaining the mixture is not limited to the following, (1) Step of adding epoxy resin (C) to the epoxy resin curing agent of the present embodiment (2) Step of adding the epoxy resin curing agent of the present embodiment to epoxy resin (C) (3) Step of adding epoxy resin (C) to the masterbatch in which the epoxy resin curing agent of the present embodiment and the dispersion medium are integrated etc. can be mentioned. The mixing method included in the method for producing the epoxy resin composition of the present embodiment is not particularly limited either, and can be appropriately selected from, for example, a method using a planetary mixer or a method using a three-roll mill. Also, the method for producing the epoxy resin curing agent of the present embodiment is as described above.

[0115] In addition, an epoxy resin composition obtained by treating the epoxy resin composition of the present embodiment as a masterbatch-type epoxy resin curing agent composition and adding and mixing epoxy resin (C) and other additive components to the masterbatch-type epoxy resin curing agent composition is also included in the present embodiment. Examples of the mixing method include sufficiently mixing using a mixing roll such as a three-roll mill, a dissolver, a planetary mixer, a kneader, an extruder, etc. until it becomes uniform.

[0116] The epoxy resin curing agent, epoxy resin composition, and epoxy resin composition preparation liquid for a film described later of the present embodiment can also be heat-treated at a temperature of 30°C to 80°C for 1 to 168 hours. The heating method is not particularly limited, and examples include heating methods such as using an oven, an incubator, a water bath, an oil bath, etc. Also, the temperature history is not particularly limited, and for example, the temperature can be raised stepwise or all at once. When heating the epoxy resin curing agent, after the formation reaction of layer (B) is completed, the epoxy resin curing agent is allowed to stand in an environment of 5 to 12°C or lower for 8 hours or more and then heated.

[0117] 〔Specific embodiments of the epoxy resin composition〕 The epoxy resin composition of this embodiment is not limited to the following, but for example, it is suitable as a sealing material for electric and electronic components such as underfill materials and relay encapsulants, a conductive material such as a conductive paste, a heat conductive material, an insulating material, an adhesive for camera modules, a structural adhesive, a matrix resin for fiber reinforced plastics, an impregnating and fixing material for motor coils, etc. In addition to the above, the epoxy resin composition of this embodiment is not limited to the following, but for example, it is suitable for an interlayer insulating film, a film type solder resist, a sealing sheet, a conductive film, an anisotropic conductive film, a heat conductive film, etc. Regarding each of the above applications, the epoxy resin composition of one embodiment of the present invention may also serve multiple applications. Examples of such cases include, but are not limited to, when the epoxy resin composition of this embodiment contains silver particles as a filler, the conductive material obtained from the epoxy resin composition can also be a heat conductive material. As described above, the epoxy resin composition of this embodiment can be preferably applied as a sealing material, a conductive material, a heat conductive material, an insulating material, an adhesive for camera modules, a structural adhesive, a matrix resin for fiber reinforced plastics, an impregnating and fixing material, an interlayer insulating film, a film type solder resist, a sealing sheet, a conductive film, an anisotropic conductive film, and / or a heat conductive film. In other words, the sealing material, conductive material, heat conductive material, insulating material, adhesive for camera modules, structural adhesive, matrix resin for fiber reinforced plastics, impregnating and fixing material, interlayer insulating film, film type solder resist, sealing sheet, conductive film, anisotropic conductive film, and heat conductive film of this embodiment all contain the epoxy resin composition (epoxy resin curing agent) of this embodiment.

[0118] For example, when applying the epoxy resin composition of this embodiment as an underfill material, stability against heating for rapid penetration between the semiconductor chip and the substrate and excellent curability at 120°C to 150°C are required. However, since the epoxy resin composition of this embodiment contains an epoxy resin curing agent, it can possess all of these characteristics. In the case of a conductive material, the conductive particles may include solder particles, nickel particles, nano-sized metal crystals, particles with the surface of a metal coated with another metal, metal particles such as gradient particles of copper and silver, and a solvent. However, the epoxy resin curing agent of the present embodiment has a strong layer (B), so it has resistance to metal particles and also has resistance to solvents. Therefore, an epoxy resin composition containing the epoxy resin curing agent of the present embodiment can provide a conductive material having excellent stability. In the case of a thermal conductive material, a metal such as silver having high thermal conductivity, a metal oxide such as zinc oxide, a ceramic such as boron nitride, aluminum nitride, or alumina, and an inorganic filler such as silica and a curing agent are integrated. Although the thermal conductive material is required to have stability during storage, it is difficult to impart excellent stability when the curing agent is not isolated from the liquid component. Even if there is a coating layer that isolates the curing agent component from the liquid component, if its strength is not sufficient, it will be broken when colliding with the filler. The epoxy resin composition containing the epoxy resin curing agent of the present embodiment has excellent characteristics in this regard and can provide a stable thermal conductive material. Typical examples of the structural adhesive include adhesives for automotive structures. The adhesive may be placed under high temperature and high humidity conditions when applied. In this case, excellent stability against both heat and moisture is required. The epoxy resin composition containing the epoxy resin curing agent of the present embodiment can provide a structural adhesive having excellent stability against both of these. In the case of an adhesive for a camera module, for example, when actively aligning an image sensor such as a lens holder and an electronic component equipped with a CMOS sensor, a dual-curing type adhesive that cures with both light and heat is used. The dual-curing type adhesive contains both an epoxy resin and an acrylic resin. The epoxy resin composition containing the epoxy resin curing agent of the present embodiment can provide an adhesive for a camera module that combines sufficient stability and reactivity even when containing both. Matrix resins for fiber-reinforced plastics and impregnating and fixing materials for motor coils are required to have performance in the process from impregnation to curing, i.e., permeability into gaps in fine fibers or coils, stability during permeation, and curing ability. The epoxy resin composition containing the epoxy resin curing agent of the present embodiment is suitable because it can combine all of these properties.

[0119] [Film Containing the Epoxy Resin Composition of the Present Embodiment] This embodiment also includes a film having a resin composition layer containing the epoxy resin curing agent and / or the epoxy resin composition of this embodiment. In this case, the epoxy resin composition can also function as an epoxy resin curing agent or a curing accelerator. The epoxy resin composition of the present embodiment has excellent solvent resistance and is suitable for films. The film of the present embodiment has, for example, a predetermined support and a resin composition layer formed on the support from an epoxy resin composition preparation liquid described below, and may have a protective layer on the surface of the resin composition layer opposite the support, as necessary.

[0120] The support is preferably a material that can withstand the temperature during drying of the organic solvent, and examples of such supports include, but are not limited to, polyethylene terephthalate film, polyvinyl alcohol film, polyvinyl chloride film, vinyl chloride copolymer film, polyvinylidene chloride film, vinylidene chloride copolymer film, polymethyl methacrylate copolymer film, polystyrene film, polyacrylonitrile film, styrene copolymer film, polyamide film, and cellulose derivative film. These films may be stretched as necessary.

[0121] As the protective layer, a material that can sufficiently maintain the smoothness of the surface of the resin composition layer is preferable. Examples of such a protective layer include, but are not limited to, a polyethylene film, a polypropylene film, a polyethylene terephthalate film subjected to an easy-peeling treatment, an oriented polypropylene film, etc., which can be preferably used.

[0122] 〔Method for preparing an epoxy resin composition preparation liquid for a film〕 As a method for preparing an epoxy resin composition preparation liquid for forming a resin composition layer of a film, for example, a method of mixing an epoxy resin curing agent and / or an epoxy resin composition of the present embodiment, other additives, a polymer for film formation, etc., further adding an organic solvent, and mixing with a planetary mixer or the like can be mentioned. As the polymer for film formation, when the epoxy resin composition preparation liquid is coated and then the organic solvent is dried to form a film, polymers in general that have an effect of suppressing cracking, peeling, and excessive flow and have an effect of maintaining the film shape can be used. Examples of such polymers for film formation include, but are not limited to, for example, phenoxy resin, polyvinyl butyral resin, polyvinyl acetal resin, polyacrylic resin, polyimide resin, and elastomers having functional groups such as carboxyl group, hydroxyl group, vinyl group, and amino group. The polymer for film formation is sometimes called a binder polymer. There is no particular limitation on the organic solvent, and known ones can be used. Examples include, but are not limited to, hydrocarbons such as toluene, xylene, cyclohexane, mineral spirit, and solvent naphtha; ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone; esters such as ethyl acetate, n-butyl acetate, and propylene glycol monomethyl ethyl ether acetate; alcohols such as methanol, isopropanol, n-butanol, butyl cellosolve, and butyl carbitol; amide solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0123] 〔Method for Manufacturing Film〕 The film of the present embodiment can be manufactured by sequentially laminating a support, a resin composition layer, and, if necessary, a protective layer. As the lamination method of the support, the resin composition layer, and the protective layer, a known method can be adopted. For example, a preparation liquid containing the epoxy resin composition of the present embodiment and an organic solvent is prepared. First, it is applied onto the support using a known method such as an applicator or a bar coater and dried to form a resin composition layer on the support. There is no particular limitation on the drying method, and examples include an oven and hot air blowing. Also, there is no particular limitation on the drying temperature and time, but from the viewpoint of sufficiently removing the solvent while suppressing deformation of the support due to excessive heating and excessive reaction of the resin composition layer during drying, it is preferably dried within a temperature range of 50°C to 160°C and a drying time of 1 minute to 30 minutes, and more preferably dried at 80°C to 150°C for 3 minutes to 25 minutes. Note that the drying temperature may be a constant temperature or a temperature gradient may be applied. Next, if necessary, a film can be manufactured by laminating a protective layer on the formed resin composition layer.

[0124] 〔Specific Embodiments of the Film Containing the Epoxy Resin Composition of the Present Embodiment〕 The film containing the epoxy resin composition of the present embodiment is not limited to the following, and can be used, for example, as an interlayer insulating film, a film type solder resist, a sealing sheet, a conductive film, an anisotropic conductive film, a heat conductive film, etc. Since the epoxy resin composition of the present embodiment is excellent in solvent resistance and storage stability, it is possible to extend the coating time of the preparation liquid for the film epoxy resin composition containing this, and it is possible to extend the storage period of the obtained film. In addition, since the epoxy resin composition of the present embodiment has excellent curability at 150°C or lower, the film of the present embodiment also has excellent curability. Since the above characteristics are common requirements for interlayer insulating films, film-type solder resists, encapsulation sheets, conductive films, anisotropic conductive films, and heat conductive films, the film of this embodiment is suitable for these aspects.

Examples

[0125] Hereinafter, this embodiment will be described with specific examples and comparative examples, but this embodiment is not limited to the following examples and comparative examples. In the following, "parts" and "%" are based on mass unless otherwise specified.

[0126] 〔Production of Core (A) Containing Nitrogen-Containing Compound〕 (Production Example 1) 1 equivalent (in terms of epoxy group) of bisphenol A-type epoxy resin E-1 (epoxy equivalent 186 g / eq, total chlorine content 600 ppm, hydrolyzable chlorine content 50 ppm) and 1 equivalent (in terms of active hydrogen) of 2-methylimidazole were reacted at 80 °C in a 1:1 mixed solvent of n-butanol and toluene. Then, unreacted 2-methylimidazole was distilled off together with the solvent under reduced pressure to obtain a solid substance 1 at 25 °C. Next, the substance 1 was pulverized with a jet mill, and further, a classification operation by a classifier was carried out to obtain a core component 1 having a specific surface area value of 3.71 m 2 / g, a sieve undersize average particle size D 50 of 2.63 μm, a D 99 / D 50 of 5.5, and containing 0.005 mass% of 2-methylimidazole (abbreviated as "2MI" in the table). D 50 and D 99 are based on the Stokes diameter obtained by measuring with a particle size distribution meter (manufactured by Horiba, Ltd., "HORIBA LA-920") using the laser diffraction / scattering method. The particle size at the 50% sieve undersize cumulative fraction of core (A) is defined as D 50 , and the particle size at the 99% sieve undersize cumulative fraction of core (A) is defined as D 99 (the same applies to the following production examples). The specific surface area value was measured using a fully automatic BET specific surface area measuring device HM model-1201 manufactured by Mounttech Co., Ltd., with a mixed gas of N2 / He = 30 / 70 (volume ratio) as the adsorption gas (the same applies to the following production examples).

[0127] (Production Example 2) Using the core component 1, a cryptron orb manufactured by Earth Technica Co., Ltd. was used, and in an environment of a temperature of 10°C and a humidity of 30%, at a rotational speed of 13,500 rpm, a supply speed of 10 kg / hr, and an air volume of 3 m 3 / min, a shape correction treatment was performed. A cyclone type collector and a bag filter were attached to the classifier, and a classification operation was carried out to obtain a core component 2 having a specific surface area value of 2.51 m 2 / g, D 50 being 2.80 μm, D 99 / D 50 being 3.8 and containing 0.005% by mass of 2-methylimidazole.

[0128] (Production Example 3) 1 equivalent (in terms of epoxy groups) of bisphenol A type epoxy resin E-1 (epoxy equivalent 186 g / eq, total chlorine content 600 ppm, hydrolyzable chlorine content 50 ppm) and 1.2 equivalents (in terms of active hydrogen) of 2-methylimidazole were reacted at 80°C in a 1:1 mixed solvent of n-butanol and toluene. Then, excess 2-methylimidazole was distilled off together with the solvent under reduced pressure to obtain a solid substance 2 at 25°C. Next, the substance 2 was pulverized with a turbo mill, and further, a classification operation by a classifier was carried out to obtain a core component 3 having a specific surface area value of 3.61 m 2 / g, the average particle size D 50 under the sieve being 2.41 μm, D 99 / D 50 being 5.1 and containing 0.2% by mass of 2-methylimidazole.

[0129] (Production Example 4) 1 equivalent (in terms of epoxy groups) of bisphenol F type epoxy resin E-2 (BisF resin, epoxy equivalent 172 g / eq, total chlorine content 500 ppm, hydrolyzable chlorine content 100 ppm) and 1 equivalent (in terms of active hydrogen) of 2-methylimidazole were reacted at 80 °C in a 1:1 mixed solvent of n-butanol and toluene. Thereafter, excess 2-methylimidazole and the solvent were distilled off under reduced pressure to obtain a solid substance 3 at 25 °C. The obtained substance 3 was pulverized with a turbo mill, and had a specific surface area value of 3.91 m 2 / g, an average particle size D 50 under the sieve of 2.55 μm, and a particle size distribution with D 99 / D 50 of 4.0, to obtain a core component 4 containing 0.01% by mass of 2-methylimidazole.

[0130] (Production Example 5) 1 equivalent (in terms of epoxy groups) of bisphenol A type epoxy resin E-1 (epoxy equivalent 186 g / eq, total chlorine content 600 ppm, hydrolyzable chlorine content 50 ppm) and 1 equivalent of diethylenetriamine (abbreviated as "DETA" in the table) were reacted at 80 °C in a 1:1 mixed solvent of xylene and isopropyl alcohol. Thereafter, excess diethylenetriamine and the solvent were distilled off under reduced pressure to obtain a solid substance 4 at 25 °C. 45 g of the substance 4, 45 g of the substance 1, and 11 g of 1,4-diazabicyclo[2.2.2]octane (abbreviated as "DABCO" in the table) were melt-mixed at 150 °C to obtain a solid substance 5 at 25 °C. Next, the substance 5 was pulverized with a turbo mill, and further subjected to a classification operation with a classifier, to obtain a core component 5 having a specific surface area value of 2.69 m 2 / g, an average particle size D 50 under the sieve of 2.88 μm, and a particle size distribution with D 99 / D 50 of 4.7, containing 10% by mass of 1,4-diazabicyclo[2.2.2]octane, and further containing 0.1% by mass of diethylenetriamine and 2-methylimidazole combined.

[0131] (Production Example 6) The substance 1 was pulverized with a jet mill, and further subjected to a classification operation using a classifier to obtain a core component 6 having a specific surface area value of 4.32 m 2 / g, a sieve bottom average particle size D 50 of 2.27 μm, a particle size distribution with D 99 / D 50 of 3.4, and containing 0.005% by mass of 2-methylimidazole.

[0132] [Example 1] 100 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent 186 g / eq, total chlorine content 600 ppm, hydrolyzable chlorine content 50 ppm), 100 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent 172 g / eq, total chlorine content 500 ppm, hydrolyzable chlorine content 100 ppm), 100 parts by mass of core component 1, and 10 parts by mass of core surface coating material C-1 (MR-400 manufactured by Nippon Polyurethane Co., Ltd.) were dispersed and mixed, and then reacted at 55°C for 5 hours. Then, it was allowed to stand for 12 hours under the condition set at 9°C (standing step) to obtain a masterbatch type epoxy resin curing agent composition 1. In the above standing step, the temperature was monitored, and it was confirmed that the difference between the lowest temperature T L and the highest temperature T H was 4°C or less. That is, it was confirmed that the temperature change when allowed to stand for 12 hours under the condition set at 9°C was in the range of 9°C ± 2°C (the temperature change in the standing step was confirmed in the same manner hereinafter).

[0133] (Evaluation of the Dyeability of Layer (B)) First, 10.6 mL of the main agent (Quetol 812, manufactured by Nisshin EM Co., Ltd.), 9.4 mL of the curing agent (Methyl nadic anhydride: MNA, manufactured by Nisshin EM Co., Ltd.), and 0.34 mL of the reaction accelerator (2,4,6-Tris(dimethyl amino methyl)phenol, manufactured by Nisshin EM Co., Ltd.: DMP-30) were mixed and stirred with a stirrer for 15 minutes, and then the bubbles were removed by vacuum degassing to obtain a dyeing epoxy resin composition. Next, after adding toluene to the masterbatch-type epoxy resin curing agent composition 1, the epoxy resin and the curing agent component were separated by a centrifuge, and the curing agent component was collected and dried to obtain the epoxy resin curing agent 1. After electron staining by allowing the obtained epoxy resin curing agent 1 to coexist with ruthenium tetroxide in a sealed and light-shielded container at room temperature and atmospheric pressure for 10 minutes, it was mixed with the aforementioned epoxy resin composition for staining and cured at 40°C for 42 hours. A cured product in which the epoxy resin curing agent 1 was embedded was sliced into 80 nm sections using an ultramicrotome. Then, the sections were allowed to coexist with osmium tetroxide in a sealed and light-shielded container at room temperature and atmospheric pressure for 2 hours to obtain an observation sample electron-stained with osmium tetroxide vapor. An electron beam was irradiated to the observation sample with a TEM, and the focus was adjusted so that it matched the sample. Observation was carried out at an acceleration voltage of 120 kV and a magnification of 30,000 times to obtain Image 1 of Core (A) and Layer (B). The obtained Image 1 was read using the image analysis software ImageJ (ImageJ 1.53t Java 1.8.0_345 (64-bit)), and after applying a median filter (Radius 2.0 pixels), a line segment was drawn from the outermost part of Layer (B) to include the boundary between Core (A) and Layer (B) to obtain Image 1' (Figure 1). A graph 1 was obtained by graphing the luminance along this line segment (Figure 2). In Graph 1, the vertical axis represents the luminance, and the horizontal axis represents the distance from the end on the outermost side of Layer (B) in the above line segment (the same applies to the following graphs).

[0134] From the obtained Image 1' and Graph 1, it was confirmed that the epoxy resin curing agent 1 has a region in the interior of Layer (B) that has a higher luminance than the outermost luminance and the luminance at the above boundary when obtaining a luminance graph between the outermost part of Layer (B) and the boundary between Layer (B) and Core (A).

[0135] [Example 2] 100 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent: 186 g / eq, total chlorine content: 600 ppm, hydrolyzable chlorine content: 50 ppm), 100 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent: 172 g / eq, total chlorine content: 500 ppm, hydrolyzable chlorine content: 100 ppm), 200 parts by mass of core component 2, and 10 parts by mass of core surface coating material C-1 (MR-400 manufactured by Nippon Polyurethane Co., Ltd.) were dispersed and mixed, and then reacted at 55°C for 5 hours. After that, it was allowed to stand for 12 hours under the condition set at 9°C to obtain masterbatch type epoxy resin curing agent composition 2. It should be noted that it was confirmed that the temperature change during standing for 12 hours under the condition set at 9°C was in the range of 9°C ± 2°C.

[0136] In the same manner as masterbatch type epoxy resin curing agent composition 1, the dyeability of epoxy resin curing agent 2 contained in masterbatch type epoxy resin curing agent composition 2 was confirmed. As a result, when obtaining the luminance graph between the outermost layer of layer (B) and the boundary between layer (B) and core (A), it was confirmed that the inside of layer (B) had a region with a luminance higher than that of the outermost layer and the luminance of the above boundary.

[0137] 〔Example 3〕 100 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent: 186 g / eq, total chlorine content: 600 ppm, hydrolyzable chlorine content: 50 ppm), 100 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent: 172 g / eq, total chlorine content: 500 ppm, hydrolyzable chlorine content: 100 ppm), 100 parts by mass of core component 3, and 10 parts by mass of core surface coating material C-2 (Coronate T100 manufactured by Tosoh Corporation) were dispersed and mixed, and then reacted at 55°C for 5 hours. After that, it was allowed to stand for 12 hours under the condition set at 9°C to obtain masterbatch type epoxy resin curing agent composition 3. It should be noted that it was confirmed that the temperature change during standing for 12 hours under the condition set at 9°C was in the range of 9°C ± 2°C.

[0138] The masterbatch-type epoxy resin curing agent composition 3 was used in the same manner as the masterbatch-type epoxy resin curing agent composition 1 to confirm the dyeability of the epoxy resin curing agent 3. That is, in the image 2 obtained by image analysis of the TEM observation image of the epoxy resin curing agent 3, an image 2' was drawn at a predetermined position to confirm the dyeability (Fig. 3). A graph 2 in which the luminance was graphed along this line segment was obtained (Fig. 4). From the image 2' and the graph 2, it was confirmed that the epoxy resin curing agent 3 has a region in the interior of the layer (B) having a luminance higher than the luminance of the outermost layer and the luminance of the boundary between the layer (B) and the core (A) when obtaining the luminance graph between the outermost layer of the layer (B) and the boundary between the layer (B) and the core (A).

[0139] 〔Example 4〕 100 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent 186 g / eq, total chlorine content 600 ppm, hydrolyzable chlorine content 50 ppm), 100 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent 172 g / eq, total chlorine content 500 ppm, hydrolyzable chlorine content 100 ppm), 100 parts by mass of core component 4, 4 parts by mass of core surface coating material C-1 (MR-400 manufactured by Nippon Polyurethane Co., Ltd.) and 3 parts by mass of core surface coating material C-3 (Duranate TPA-100 manufactured by Asahi Kasei Corporation) were dispersed and mixed, and then reacted at 55 °C for 5 hours, and then allowed to stand for 12 hours under conditions set at 9 °C to obtain a masterbatch-type epoxy resin curing agent composition 4. It was confirmed that the temperature change during standing for 12 hours under conditions set at 9 °C was in the range of 9 °C ± 2 °C.

[0140] The masterbatch-type epoxy resin curing agent composition 4 was examined for the dyeability of the epoxy resin curing agent 4 contained therein in the same manner as the masterbatch-type epoxy resin curing agent composition 1. That is, in the image I obtained by analyzing the TEM observation image of the epoxy resin curing agent 4, an image I’ was obtained by drawing a line at a predetermined position to confirm the dyeability (Fig. 5). A graph G was obtained by graphing the luminance along this line segment (Fig. 6). From the image I’ and the graph G, it was confirmed that the epoxy resin curing agent 4 has a region in the interior of layer (B) having a luminance higher than the luminance of the outermost layer and the luminance of the above-mentioned boundary when obtaining the luminance graph between the outermost layer of layer (B) and the boundary between layer (B) and core (A). Further, in Fig. 5, since the boundary between layer (B) and the epoxy resin composition region for dyeing appears wavy or wrinkled, it was suggested that the surface of layer (B) is a rough surface. When comparing Fig. 5 (epoxy resin curing agent 4) with Fig. 1 (epoxy resin curing agent 1) and Fig. 3 (epoxy resin curing agent 3), in Figs. 1 and 3, since the boundary between layer (B) and the epoxy resin composition region for dyeing appears linear, it was suggested that the surface of layer (B) in the epoxy resin curing agents 1 and 3 is a smoother surface compared to the epoxy resin curing agent 4 described later.

[0141] 〔Example 5〕 100 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent 186 g / eq, total chlorine content 600 ppm, hydrolyzable chlorine content 50 ppm), 100 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent 172 g / eq, total chlorine content 500 ppm, hydrolyzable chlorine content 100 ppm), 120 parts by mass of core component 5, and 10 parts by mass of core surface coating material C-1 (MR-400 manufactured by Nippon Polyurethane Co., Ltd.) were dispersed and mixed, and then reacted at 55°C for 5 hours, and then allowed to stand for 12 hours under the condition set at 9°C to obtain a masterbatch-type epoxy resin curing agent composition 5. It was confirmed that the temperature change during standing for 12 hours under the condition set at 9°C was in the range of 9°C ± 2°C.

[0142] The masterbatch type epoxy resin curing agent composition 5 was treated in the same manner as the masterbatch type epoxy resin curing agent composition 1, and as a result of confirming the dyeability of the epoxy resin curing agent 5 contained therein, when obtaining the luminance graph from the outermost layer of layer (B) to the boundary between layer (B) and core (A), it was confirmed that the interior of layer (B) has a region having a luminance higher than the luminance of the outermost layer and the luminance of the said boundary.

[0143] 〔Example 6〕 90 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent 186 g / eq, total chlorine content 600 ppm, hydrolyzable chlorine content 50 ppm), 90 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent 172 g / eq, total chlorine content 500 ppm, hydrolyzable chlorine content 100 ppm), 20 parts by mass of naphthalene type epoxy resin E-3 (epoxy equivalent 142 g / eq, total chlorine content 700 ppm, "HP4032D" manufactured by DIC Corporation), 100 parts by mass of core component 1, and 10 parts by mass of core surface coating material C-1 (MR-400 manufactured by Nippon Polyurethane Co., Ltd.) were dispersed and mixed, then reacted at 55°C for 5 hours, and then allowed to stand for 12 hours under the condition set at 9°C to obtain a masterbatch type epoxy resin curing agent composition 6. Incidentally, it was confirmed that the temperature change during standing for 12 hours under the condition set at 9°C was in the range of 9°C ± 2°C.

[0144] The masterbatch type epoxy resin curing agent composition 6 was treated in the same manner as the masterbatch type epoxy resin curing agent composition 1, and as a result of confirming the dyeability of the epoxy resin curing agent 6 contained therein, when obtaining the luminance graph from the outermost layer of layer (B) to the boundary between layer (B) and core (A), it was confirmed that the interior of layer (B) has a region having a luminance higher than the luminance of the outermost layer and the luminance of the said boundary.

[0145] 〔Example 7〕 100 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent 186 g / eq, total chlorine content 600 ppm, hydrolyzable chlorine content 50 ppm), 100 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent 172 g / eq, total chlorine content 500 ppm, hydrolyzable chlorine content 100 ppm), 100 parts by mass of core component 1, and 10 parts by mass of core surface coating material C-1 (MR-400 manufactured by Nippon Polyurethane Co., Ltd.) were dispersed and mixed, then reacted at 55°C for 5 hours, and then allowed to stand for 8 hours under the condition set at 6°C to obtain a masterbatch type epoxy resin curing agent composition 7. In addition, it was confirmed that the temperature change during standing for 8 hours under the condition set at 6°C was in the range of 6°C ± 2°C.

[0146] The masterbatch type epoxy resin curing agent composition 7 was used in the same manner as the masterbatch type epoxy resin curing agent composition 1 to confirm the dyeability of the epoxy resin curing agent 7 contained therein. As a result, when obtaining the luminance graph between the outermost layer of layer (B) and the boundary between layer (B) and core (A), it was confirmed that the inside of layer (B) had a region with a luminance higher than the luminance of the outermost layer and the luminance of the above boundary.

[0147] 〔Example 8〕 100 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent 186 g / eq, total chlorine content 600 ppm, hydrolyzable chlorine content 50 ppm), 100 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent 172 g / eq, total chlorine content 500 ppm, hydrolyzable chlorine content 100 ppm), 100 parts by mass of core component 1, and 10 parts by mass of core surface coating material C-1 (MR-400 manufactured by Nippon Polyurethane Co., Ltd.) were dispersed and mixed, then reacted at 55°C for 5 hours, and then allowed to stand for 24 hours under the condition set at 12°C to obtain a masterbatch type epoxy resin curing agent composition 8. In addition, it was confirmed that the temperature change during standing for 24 hours under the condition set at 12°C was in the range of 12°C ± 2°C.

[0148] The masterbatch type epoxy resin curing agent composition 8 was treated in the same manner as the masterbatch type epoxy resin curing agent composition 1, and as a result of confirming the dyeability of the epoxy resin curing agent 8 contained therein, when obtaining the luminance graph between the outermost layer of layer (B) and the boundary between layer (B) and core (A), it was confirmed that the interior of layer (B) had regions with luminance higher than the luminance of the outermost layer and the luminance of the said boundary.

[0149] 〔Example 9〕 100 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent 186 g / eq, total chlorine content 600 ppm, hydrolyzable chlorine content 50 ppm), 100 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent 172 g / eq, total chlorine content 500 ppm, hydrolyzable chlorine content 100 ppm), 100 parts by mass of core component 6, and 10 parts by mass of core surface coating material C-1 (MR-400 manufactured by Nippon Polyurethane Co., Ltd.) were dispersed and mixed, then reacted at 55 °C for 5 hours, and then allowed to stand for 12 hours under the condition set at 9 °C to obtain a masterbatch type epoxy resin curing agent composition 9. In addition, it was confirmed that the temperature change during standing for 12 hours under the condition set at 9 °C was in the range of 9 °C ± 2 °C.

[0150] The masterbatch type epoxy resin curing agent composition 9 was treated in the same manner as the masterbatch type epoxy resin curing agent composition 1, and as a result of confirming the dyeability of the epoxy resin curing agent 9 contained therein, when obtaining the luminance graph between the outermost layer of layer (B) and the boundary between layer (B) and core (A), it was confirmed that the interior of layer (B) had regions with luminance higher than the luminance of the outermost layer and the luminance of the said boundary.

[0151] 〔Comparative Example 1〕 100 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent: 186 g / eq, total chlorine content: 600 ppm, hydrolyzable chlorine content: 50 ppm), 100 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent: 172 g / eq, total chlorine content: 500 ppm, hydrolyzable chlorine content: 100 ppm), 100 parts by mass of core component 1, and 10 parts by mass of core surface coating material C-1 (MR-400 manufactured by Nippon Polyurethane Industry Co., Ltd.) were dispersed and mixed, then reacted at 55°C for 5 hours, and then allowed to stand at 25°C for 12 hours under set conditions to obtain masterbatch type epoxy resin curing agent R-1. It should be noted that it was confirmed that the temperature change during standing at 25°C for 12 hours under set conditions was in the range of 25°C ± 2°C.

[0152] The dyeability of the masterbatch type epoxy resin curing agent R-1 was confirmed in the same manner as that of the masterbatch type epoxy resin curing agent composition 1. That is, in image 3 obtained by image analysis of the TEM observation image of the epoxy resin curing agent 3, an image 3' was obtained by drawing a line at a predetermined position to confirm the dyeability (Fig. 7). A graph 3 was obtained by graphing the luminance along this line segment (Fig. 8). From image 3' and graph 3, it was confirmed that the epoxy resin curing agent R-1 does not have a region in the interior of layer (B) having a luminance higher than the luminance of the outermost layer and the luminance of the above-mentioned boundary when obtaining the luminance graph between the outermost layer of layer (B) and the boundary between layer (B) and core (A).

[0153] [Comparative Example 2] 100 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent: 186 g / eq, total chlorine content: 600 ppm, hydrolyzable chlorine content: 50 ppm), 100 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent: 172 g / eq, total chlorine content: 500 ppm, hydrolyzable chlorine content: 100 ppm), 100 parts by mass of core component 1, and 10 parts by mass of core surface coating material C-1 (MR-400 manufactured by Nippon Polyurethane Industry Co., Ltd.) were dispersed and mixed, then reacted at 55°C for 5 hours, and then allowed to stand at 50°C for 24 hours under set conditions to obtain epoxy resin curing agent R-2 of Comparative Example 2. It should be noted that it was confirmed that the temperature change during standing at 50°C for 24 hours under set conditions was in the range of 50°C ± 2°C.

[0154] The masterbatch type epoxy resin curing agent composition R-2 was treated in the same manner as the masterbatch type epoxy resin curing agent composition 1, and the dyeability of the contained epoxy resin curing agent R-2 was confirmed. As a result, when obtaining the luminance graph between the outermost layer of layer (B) and the boundary between layer (B) and core (A), it was confirmed that the interior of layer (B) has no region having a luminance higher than the luminance of the outermost layer and the luminance of the above-mentioned boundary.

[0155] [Comparative Example 3] 100 parts by mass of bisphenol A type epoxy resin E-1 (epoxy equivalent 186 g / eq, total chlorine content 600 ppm, hydrolyzable chlorine content 50 ppm), 100 parts by mass of bisphenol F type epoxy resin E-2 (epoxy equivalent 172 g / eq, total chlorine content 500 ppm, hydrolyzable chlorine content 100 ppm), 100 parts by mass of core component 1, and 20 parts by mass of core surface coating material C-1 (MR-400 manufactured by Nippon Polyurethane Co., Ltd.) were dispersed and mixed, and then reacted at 55°C for 5 hours, and then allowed to stand at 25°C for 12 hours under the set conditions to obtain the epoxy resin curing agent R-3 of Comparative Example 3. In addition, it was confirmed that the temperature change during standing at 25°C for 12 hours was in the range of 25°C ± 2°C.

[0156] The masterbatch type epoxy resin curing agent composition R-3 was treated in the same manner as the masterbatch type epoxy resin curing agent composition 1, and the dyeability of the contained epoxy resin curing agent R-3 was confirmed. As a result, when obtaining the luminance graph between the outermost layer of layer (B) and the boundary between layer (B) and core (A), it was confirmed that the interior of layer (B) has no region having a luminance higher than the luminance of the outermost layer and the luminance of the above-mentioned boundary.

[0157] [Evaluation method of properties] (Stability evaluation to low molecular weight epoxy compounds) (Preparation method of epoxy resin composition for stability evaluation to low molecular weight epoxy compounds) 30 parts of the masterbatch-type epoxy resin curing agent composition described in Examples 1 to 9 and Comparative Examples 1 to 3, 100 parts of jER828 (manufactured by Mitsubishi Chemical Corporation), and 30 parts of the low-molecular-weight epoxy compound o-CGE (ortho-cresyl glycidyl ether; viscosity at 25°C: 7 mPa·s; manufactured by Sigma-Aldrich) were weighed, and these components were stirred for 2 minutes and defoamed for 3 minutes using a non-bubbling kneader, and then mixed to prepare an epoxy resin composition for evaluating the stability to the low-molecular-weight epoxy compound. (Stability to low-molecular-weight epoxy compound) The initial viscosity immediately after preparing the epoxy resin composition for evaluating the stability to the low-molecular-weight epoxy compound and the viscosity after storage of the epoxy resin composition for evaluating the stability after storing at 40°C for 21 days were measured at room temperature (25°C) using an E-type viscometer, and the viscosity magnification after storage was calculated by the following formula (2). Viscosity magnification after storage = Viscosity after storage / Initial viscosity ···· Formula (2) Evaluation was performed according to the following criteria according to the viscosity magnification after storage. 〇: 1.0 times ≤ Viscosity magnification after storage < 1.3 times △: 1.3 times ≤ Viscosity magnification after storage < 2.0 times ×: 2.0 times ≤ Viscosity magnification after storage

[0158] (Reactivity of epoxy resin composition containing low-molecular-weight epoxy compound) Approximately 10 mg of the epoxy resin composition for evaluating the stability to the low-molecular-weight epoxy compound (uncured state) was weighed, and using DSC EXSTER7020 (manufactured by Hitachi High-Tech Science Corporation), the temperature was raised from 25°C to 250°C at a rate of 20°C / min to obtain a DSC curve, and the temperature at the point where the heat flow was maximum was defined as the DSC exothermic peak temperature. Evaluation was performed according to the following criteria according to the exothermic peak temperature. ◎◎: Exothermic peak temperature ≤ 120°C ◎: 120°C < Exothermic peak temperature ≤ 130°C 〇: 130°C < Exothermic peak temperature ≤ 140°C △: 140°C < Exothermic peak temperature ≤ 150°C ×: 150°C < Exothermic peak temperature

[0159] (Stability evaluation to MEK) (Method for preparing epoxy resin composition for stability evaluation to MEK) A liquid obtained by mixing and dissolving 50 parts by mass of jER828 (manufactured by Mitsubishi Chemical), 50 parts by mass of PKHB (manufactured by Gabriel Phenoxies), and 100 parts by mass of MEK was obtained. Further, 15 parts by mass of the masterbatch type epoxy resin curing agent composition described in Examples 1 to 9 and Comparative Examples 1 to 3 was added to obtain an epoxy resin composition for stability evaluation to MEK. (Stability to MEK) The initial viscosity immediately after preparing the epoxy resin composition for stability evaluation to MEK and the viscosity after storage after leaving the stability evaluation epoxy resin composition at 25 ° C for 24 hours were measured at room temperature (25 ° C) using an E-type viscometer, and the viscosity magnification after storage was calculated by the following formula (3). Viscosity magnification after storage = Viscosity after storage / Initial viscosity ···· Formula (3) Evaluation was performed according to the following criteria according to the viscosity magnification after storage. 〇: 1.0 times ≤ Viscosity magnification after storage < 2.0 times △: 2.0 times ≤ Viscosity magnification after storage < 3.0 times ×: 3.0 times ≤ Viscosity magnification after storage

[0160] (Stability evaluation to low molecular weight acrylic compound) (Method for preparing epoxy resin composition for stability evaluation to low molecular weight acrylic compound) 50 parts by mass of the masterbatch type epoxy resin curing agent composition described in Examples 1 to 9 and Comparative Examples 1 to 3, 100 parts by mass of jER828 (manufactured by Mitsubishi Chemical), and 50 parts by mass of epoxy acrylate (epoxy ester 3000A manufactured by Kyoeisha Chemical Co., Ltd.) were weighed, and these components were stirred for 2 minutes and defoamed for 3 minutes with a non-bubbling kneader and mixed to prepare an epoxy resin composition for stability evaluation to low molecular weight acrylic compound. (Stability to low molecular weight acrylic compound) The initial viscosity immediately after preparing the epoxy resin composition for evaluating the stability to the low molecular weight acrylic compound and the viscosity after storage after leaving the epoxy resin composition for evaluating the stability at 40 °C for 7 days were measured at room temperature (25 °C) using an E-type viscometer, and the viscosity magnification after storage was calculated by the following formula (4). Viscosity magnification after storage = Viscosity after storage / Initial viscosity ···· Formula (4) Evaluation was performed according to the following criteria according to the viscosity magnification after storage. 〇: 1.0-fold ≤ Viscosity magnification after storage < 1.5-fold △: 1.5-fold ≤ Viscosity magnification after storage < 2.0-fold ×: 2.0-fold ≤ Viscosity magnification after storage

[0161] (Reactivity of epoxy resin composition containing low molecular weight acrylic compound) Approximately 10 mg of the epoxy resin composition for evaluating the stability to the low molecular weight acrylic compound (uncured state) was weighed, and using EXSTER7020 (manufactured by Hitachi High-Tech Science Corporation), the temperature was raised from 25 °C to 250 °C at a rate of 20 °C / min to obtain a DSC curve, and the temperature at the point where the heat flow was maximum was defined as the DSC exothermic peak temperature. Evaluation was performed according to the following criteria according to the exothermic peak temperature. ◎◎: Exothermic peak temperature ≤ 120 °C ◎ : 120 °C < Exothermic peak temperature ≤ 130 °C 〇 : 130 °C < Exothermic peak temperature ≤ 140 °C △ : 140 °C < Exothermic peak temperature ≤ 150 °C × : 150 °C < Exothermic peak temperature

[0162] (Appearance evaluation of micro region) (Method for preparing epoxy resin composition for appearance evaluation of micro region) 15 parts by mass of the masterbatch type epoxy resin curing agent composition described in Examples 1 to 9 and Comparative Examples 1 to 3, 30 parts by mass of jER828 (manufactured by Mitsubishi Chemical Corporation), 5 parts by mass of the low molecular weight epoxy compound o-CGE (ortho-cresyl glycidyl ether; viscosity at 25 °C: 7 mPa·s; manufactured by Sigma-Aldrich), and SO-E2 (spherical silica manufactured by Admatechs; D 50After weighing 50 parts by mass of (with a particle size of 0.8 μm), etc., these components were stirred for 2 minutes and defoamed for 3 minutes using a non-bubbling kneader, and then mixed to prepare an epoxy resin composition for evaluating the appearance of a micro region. (Appearance evaluation of the micro region) The epoxy resin composition for evaluating the appearance of the micro region was held in an open state at 180 °C for 1 hour to obtain a cured product. After cutting the obtained cured product with a diamond cutter, it was polished with sandpaper, and after vapor-depositing gold on the surface, the polished surface was observed with a SEM at a magnification of 1000 times. The obtained SEM image was binarized, and the area ratio of the region without fillers having an equivalent circle diameter of 3 μm or more was calculated. According to the area ratio of the region without fillers, evaluation was carried out according to the following criteria. 〇: Less than 5% ×: 5% or more

[0163] Table 1 shows the weight percentage of low molecular weight amines with a molecular weight of 50 to 300 contained in the core (A) of Examples 1 to 9 and Comparative Examples 1 to 3, the dyeability of the layer (B), and the properties of the epoxy resin composition adjusted for each evaluation item. In addition, the dyeability of the layer (B) was evaluated according to the following criteria. 〇: When obtaining the luminance graph between the outermost part of the layer (B) and the boundary between the layer (B) and the core (A), the inside of the layer (B) has a region having a luminance higher than the luminance of the outermost part and the luminance of the above boundary. ×: When obtaining the luminance graph between the outermost part of the layer (B) and the boundary between the layer (B) and the core (A), the inside of the layer (B) does not have a region having a luminance higher than the luminance of the outermost part and the luminance of the above boundary.

[0164]

Table 1

[0165] When comparing the examples and comparative examples, when obtaining the luminance graph from the outermost layer of layer (B) to the boundary between layer (B) and core (A), it was found that epoxy resin curing agents 1 to 9 having portions with higher luminance inside layer (B) than the outermost layer and the boundary between layer (B) and core (A) achieved both excellent stability and reactivity with respect to low-molecular epoxy compounds, MEK, and low-molecular acrylic resins.

[0166] Also, in terms of the appearance of the micro region, when obtaining the luminance graph from the outermost layer of layer (B) to the boundary between layer (B) and core (A), it was found to be excellent by having portions with higher luminance inside layer (B) than the outermost layer and the boundary between layer (B) and core (A). The appearance in Example 1 is shown in FIG. 9, and the appearance in Comparative Example 1 is shown in FIG. 10, respectively.

[0167] Here, from the results of Comparative Examples 1 to 3, when heat-treating the masterbatch-type epoxy resin curing agent composition, increasing the amount of the core surface coating material, and under conditions where the temperature is not controlled, when obtaining the luminance graph from the outermost layer of layer (B) to the boundary between layer (B) and core (A), it was found that an epoxy resin curing agent having portions with higher luminance inside layer (B) than the outermost layer and the boundary between layer (B) and core (A) could not be obtained.

[0168] (Effect of adding component (D)) To the epoxy resin composition for evaluating the stability to low-molecular epoxy compounds using the masterbatch-type epoxy resin curing agent composition of Example 1, 3 parts by mass of bisphenol A (2,3-dihydroxypropyl) glycidyl ether (manufactured by Merck) was further added as component (D), and the stability evaluation and reactivity evaluation to low-molecular epoxy compounds were carried out. As a result, the stability to low-molecular epoxy compounds was ○, and the reactivity of the epoxy resin composition containing the low-molecular epoxy compound was ◎◎. It was found that the reactivity was improved while maintaining the stability.

[0169] As described above, the present embodiment has been explained, but the present invention is not limited thereto and can be appropriately changed without departing from the gist of the invention.

Industrial Applicability

[0170] The epoxy resin curing agent and epoxy resin composition of this embodiment impart excellent reactivity and stability even when coexisting with a low-molecular epoxy compound, a solvent, and a low-molecular acrylic compound, and are also excellent in the appearance of a minute region. Therefore, they have industrial applicability in sealing materials for electric and electronic parts such as underfill materials and relay encapsulants, conductive materials such as conductive pastes, heat conductive materials, insulating materials, adhesives for camera modules, structural adhesives, matrix resins for fiber reinforced plastics, impregnating and fixing materials for motor coils, and the like. In addition, since the epoxy resin curing agent and epoxy resin composition of this embodiment have excellent solvent resistance, they also have industrial applicability in film applications such as interlayer insulation films, film-type solder resists, encapsulation sheets, conductive films, anisotropic conductive films, and heat conductive films.

Claims

1. A core (A) containing a nitrogen-containing compound, A layer (B) covering the core (A), An epoxy resin curing agent having, When the epoxy resin curing agent is stained with ruthenium tetroxide and osmium tetroxide and then observed with a transmission electron microscope to obtain a luminance graph by image processing, the interior of the layer (B) has a region having a luminance α, and the luminance α is higher than the luminance β at the outermost part of the layer (B) and the luminance γ at the boundary between the layer (B) and the core (A). An epoxy resin curing agent.

2. The epoxy resin curing agent according to claim 1, wherein the core (A) contains 0.001 to 20% by mass of an amine compound (a) having a molecular weight of 50 to 300.

3. The epoxy resin curing agent according to claim 1, wherein the core (A) contains at least one selected from the group consisting of imidazoles, aliphatic amine compounds, and cyclic amine compounds containing tertiary amines.

4. The epoxy resin curing agent according to claim 1, wherein the core (A) contains an imidazole-based amine adduct compound.

5. The particle size D of the undersize integrated fraction of 50% of the core (A) 50 is more than 0.3 μm and 12 μm or less, The epoxy resin curing agent according to claim 1

6. The particle size D of the undersize integrated fraction of 99% of the core (A) 99 and the D 50 The ratio with is D 99 / D 50 is 8 or less as, The epoxy resin curing agent according to claim 5.

7. The value obtained by multiplying the specific surface area value Y (m 2 / g) of the core (A) by the D 50 (μm) is 3.0 or more and 9.0 or less. The epoxy resin curing agent according to claim 5.

8. The value obtained by multiplying the specific surface area value Y (m 2 / g) of the core (A) by the D 50 (μm) is more than 9.0 and 18.0 or less. The epoxy resin curing agent according to claim 5.

9. An epoxy resin composition comprising the epoxy resin curing agent according to claim 1 and an epoxy resin (C).

10. The epoxy resin composition according to claim 9, wherein the mass ratio of the epoxy resin curing agent to the epoxy resin (C) is 0.1:100 to 1000:100 as the epoxy resin curing agent:epoxy resin (C).

11. The epoxy resin composition according to claim 9, further comprising an alcohol compound (D) represented by the following formula (1). 【Chemical 1】 (In formula (1), X 1 represents an alkylene group having 2 to 5 carbon atoms which may have a substituent R, and substituents R 1 to R 5 each independently represent a hydrogen atom, an alkyl group, an unsaturated aliphatic group, an aromatic group, a substituent containing a heteroatom, or a halogen atom, and where any one selected from R 1 to R 5 may be a condensed ring compound constituting the same ring.)

12. The epoxy resin composition according to claim 11, wherein the content of the alcohol compound (D) is 0.0001% by mass or more and 5% by mass or less based on the total amount of the epoxy resin composition.

13. The epoxy resin composition according to claim 11, wherein the alcohol compound (D) contains at least one selected from the group consisting of 3-phenoxy-1-propanol, 3-phenoxy-1,2-propanediol, 3-phenoxy-1,3-propanediol, 3-(ortho-tolyloxy)-1,2-propanediol, 3-(2-methoxyphenoxy)propane-1,2-diol, bisphenol A (3-hydroxypropyl) glycidyl ether, and bisphenol A (2,3-dihydroxypropyl) glycidyl ether.

14. The core (A) contains 0.001 to 20% by mass of an amine compound (a) having a molecular weight of 50 to 300, The epoxy resin composition according to claim 13, wherein the amine compound (a) contains at least one selected from the group consisting of imidazoles, aliphatic amine compounds, and cyclic amine compounds containing a tertiary amine.

15. A sealing material comprising the epoxy resin curing agent according to any one of claims 1 to 8, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

16. A conductive material comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

17. A thermally conductive material comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

18. An insulating material comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

19. An adhesive for a camera module comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

20. A structural adhesive comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

21. A matrix resin for a fiber-reinforced plastic comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

22. An impregnating fixing material comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

23. An interlayer insulating film comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

24. A film-type solder resist comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

25. A sealing sheet comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

26. A conductive film comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

27. An anisotropic conductive film comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

28. A thermally conductive film comprising the epoxy resin curing agent according to any one of claims 1 to 3, or the epoxy resin composition according to any one of claims 9, 11, 13, and 14.

29. A step (S1) of electron staining an epoxy resin curing agent having a core (A) and a layer (B) covering the core (A) with ruthenium tetroxide; A step (S2) of obtaining a cured product of the composition containing the epoxy resin curing agent that has undergone the step (S1); A step (S3) of electron staining a section of the cured product with osmium tetroxide; A method for producing a stained cured product, comprising the above steps.

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