JP2537736B2 - Epoxy resin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition in which the toughness of a polyfunctional naphthalene type epoxy resin is improved.

[0002]

2. Description of the Related Art Epoxy resins have excellent electrical properties, adhesiveness, thermal properties, etc., but are generally fragile and easily cracked by stress distortion during curing or use, heat or mechanical shock. There is. For this problem, use of a curing agent having a long-chain aliphatic group and a rubber-like property, addition of a compound having an elastomeric property, addition of a plasticizer such as asphalt substance or glycol, glass fiber, aramid fiber, carbon Fibers and other fibers have been added, and the epoxy compound itself has been introduced with a molecular group exhibiting rubber elasticity to strengthen the structure (Koichi Ochi, Polymer 38
(3), 200 (1989)).

[0003]

Among these epoxy resins, the naphthalene type epoxy resin has been attracting attention as an epoxy resin that provides high heat resistance and low hygroscopicity.
There is a problem that it is extremely brittle and its characteristics cannot be fully exhibited. The present invention has been made in view of this problem, and an epoxy resin composition that provides improved toughness without reducing features such as excellent heat resistance and low hygroscopicity of a polyfunctional naphthalene-type epoxy resin. To provide.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has found that an epoxy resin composition comprising a polyfunctional naphthalene type epoxy resin and a curing agent contains a phenolic hydroxyl group. The polyamide-polybutadiene-acrylonitrile block copolymer contained in the epoxy resin composition is contained in the epoxy resin composition as a polyfunctional modified naphthalene type epoxy resin modified product through the phenolic hydroxyl group, whereby the toughness is remarkably improved. I found it. Furthermore, in the epoxy resin composition containing the polyamide-polybutadiene-acrylonitrile block copolymer containing a phenolic hydroxyl group, a polybutadiene-acrylonitrile copolymer having functional groups capable of reacting with the epoxy resin at both ends is further contained. Thus, the toughness is further improved by allowing the cured epoxy resin composition to have an island structure.

The polyfunctional naphthalene type epoxy resin of the present invention means an epoxy resin having two or more epoxy groups in the naphthalene ring, and such an epoxy resin has two or more hydroxyl groups or carboxy groups, or one or more hydroxyl groups. It is obtained by a method such as reacting a naphthalene compound having an amino group added thereto with chloroglycidyl. Specific examples thereof include 1,3-diglycidyl ether naphthalene, 1,4
-Diglycidyl ether naphthalene, 1,5-diglycidyl ether naphthalene, 1,6-diglycidyl ether naphthalene, 2,6-diglycidyl ether naphthalene, 2,7-diglycidyl ether naphthalene, 1,3
-Diglycidyl ester naphthalene, 1,4-diglycidyl ester naphthalene, 1,5-diglycidyl ester naphthalene, 1,6-diglycidyl ester naphthalene, 2,6-diglycidyl ester naphthalene, 2,7
-Diglycidyl ester naphthalene, 1,3-tetraglycidyl amine naphthalene, 1,4-tetraglycidyl amine naphthalene, 1,5-tetraglycidyl amine naphthalene, 1,6-tetraglycidyl amine naphthalene, 1,8-tetraglycidyl amine naphthalene , 2,
There are 6-tetraglycidylamine naphthalene, 2,7-tetraglycidylamine naphthalene, and the like, but the present invention is not limited to these, and these can be used alone or in combination. In addition, other epoxies can be mixed and used as needed.

The above block copolymer used in the present invention can be synthesized by the following method. For example, an excess amount of diamine is added to a dicarboxylic acid component containing a dicarboxylic acid having a phenolic hydroxyl group, and these are added, for example, using a condensing agent in the presence of a phosphite ester and a pyridine derivative to produce N-methyl- Heating and stirring in an organic solvent represented by 2-pyrrolidone under an inert atmosphere such as nitrogen,
A condensation reaction is performed to generate a polyamide oligomer containing a phenolic hydroxyl group. As a result, to the obtained phenolic hydroxyl group-containing polyamide oligomer solution having amino groups at both ends, polybutadiene-acrylonitrile copolymer having carboxyl groups at both ends was added,
It can be obtained by polycondensation. Further, this dicarboxylic acid was added to diamine in excess to synthesize the polyamide having both carboxylic acid groups at both ends, and a polybutadiene-acrylonitrile copolymer having both amino terminals at both ends was used as a block. It can also be converted. Furthermore, it is also possible to modify the terminals of these polyamides or polybutadiene-acrylonitrile copolymers to make them functional groups capable of blocking. Other combinations of functional groups include combinations of vinyl groups and -NH groups or -SH groups. In order to allow the polyamide portion of the block copolymer thus synthesized to contain a phenolic hydroxyl group, the dicarboxylic acid or diamine is allowed to contain a dicarboxylic acid containing a phenolic hydroxyl group or a diamine containing a phenolic hydroxyl group. It is possible to carry out the above polycondensation.

Examples of the dicarboxylic acid having a phenolic hydroxyl group include 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, 2-hydroxyphthalic acid, 3-hydroxyphthalic acid, 2-hydroxyterephthalic acid and dicarboxylic acid having no phenolic hydroxyl group. Examples of the acid include phthalic acid, isophthalic acid, terephthalic acid, dicarboxylic naphthalene, succinic acid, fumaric acid, glutaric acid, adipic acid, 1,3-cyclohexanedicarboxylic acid, 4,4′-
Examples thereof include diphenyldicarboxylic acid and 3,3′-methylenedibenzoic acid. As the diamine component, 3,3′-diamine-4,4′-dihydroxyphenylmethane, 2,2-as a diamine containing a phenolic hydroxyl group.
Bis (3-amino-4-hydroxyphenyl) hexafluoroporane, 2,2-bis (3-amino-4-hydroxyphenyl) difluoromethane, 3,4-diamino-
1,5-benzenediol, 3,3'-dihydroxy-
4,4'-diaminobisphenyl, 3,3'-diamino-4,4'-dihydroxybiphenyl, 2,2-bis (3-amino-4-hydroxyphenyl) ketone, 2,
2-bis (3-amino-4-hydroxyphenyl) sulfide, 2,2-bis (3-amino-4-hydroxyphenyl) ether, 2,2-bis (3-amino-4-hydroxyphenyl) sulfone, 2 , 2-bis (3-amino-4-hydroxyphenyl) propane, 2,2-bis (3-hydroxy-4-aminophenyl) propane,
2,2-bis (3-hydroxy-4-aminophenyl)
As diamines containing no phenolic hydroxyl group such as methane, 3,3'-oxydianiline, 3,4'-oxydianiline, 4,4'-oxydianiline, diaminonaphthalene, piperazine, hexanetylenediamine, tetra Methylenediamine, m-xylenediamine, 4,4 '
-Diaminodiphenylmethane, 4,4'-diaminobenzophenone, 2,2'-bis (4-aminophenyl) propane, 3,3'-diaminodiphenylsulfone, 3,
Examples thereof include 3'-diaminodiphenyl, but the present invention is not limited thereto.

Further, a polybutadiene-acrylonitrile copolymer having various functional groups at both ends is commercially available from Goodrich as Hycar CTBN, which is used for blocking with the above-mentioned phenolic hydroxyl group-containing polyamide. be able to.

The method of introducing the phenol-hydroxyl group-containing polyamide-polybutadiene-acrylonitrile block copolymer used in the present invention into an epoxy resin composition comprising a polyfunctional naphthalene type epoxy resin and a curing agent is the block copolymer. There are a method of mixing with an epoxy resin composition and a method of introducing this block copolymer after modifying it with the epoxy resin, but both methods can be used in the present invention. In the former case, a solvent may be used if necessary. The latter method of denaturation is
The reaction is performed through the reaction between the phenolic hydroxyl group and the epoxide group of the polyfunctional naphthalene type epoxy resin. This reaction can be carried out by heating and mixing this compound in a solvent or without a solvent. In this case, a reaction accelerator represented by triphenylphosphine can be used if necessary. As the reaction solvent, an amide solvent represented by N, N-dimethylacetamide or an ether solvent represented by tetrahydrofuran can be used.
In addition, this reaction temperature is generally 250 ° C. or lower, preferably 180 ° C. or lower because side reactions are less likely to occur, which is preferable.

As the curing agent for the epoxy resin used in the present invention, for example, bis (4-aminophenyl) sulfone, bis (4-aminophenyl) methane, 1,5-diaminonaphthalene, p-phenylenediamine, m- Aromatic amine curing agents such as phenylenediamine, o-phenylenediamine, 2,6-dichloro-1,4-benzenediamine, 1,3-di (p-aminophenyl) propane, m-xylenediamine, ethylenediamine, diethylenetriamine , Tetraethylenepentamine, diethylaminopropylamine, hexamethylenediamine, mentenediamine, isophoronediamine, bis (4-amino-3)
-Methyldicyclohexyl) methane, polymethylenediamine, polyetherdiamine and other aliphatic amine compounds, polyaminoamide compounds, dodecyl succinic anhydride, polyadipic acid anhydride, polyazelaic acid anhydride and other aliphatic acid anhydrides, hexahydro Aliphatic acid anhydrides such as phthalic anhydride, methylhexahydrophthalic anhydride, phthalic anhydride, trimellitic anhydride, benzophenone tetracarboxylic acid anhydride, aromatics such as ethylene glycol bis trimellitate, glycerol tris trimellitate Acid anhydrides, phenol compounds, phenol resins, amino resins, urea resins, melamine resins, guanidines represented by dicyandiamide, dihydrazines, imidazoles, Lewis acids, Bronsted acid salts, polymercaptons, isocyanates Block isocyanates, and the like, but not limited thereto.

In the present invention, a modified epoxy resin obtained by reacting a polyfunctional naphthalene type epoxy resin with a phenolic hydroxyl group-containing polyamide-polybutadiene-acrylonitrile block copolymer through the phenolic hydroxyl group,
The toughened epoxy resin composition of the present invention can be obtained by uniformly mixing the epoxy resin and the curing agent in a solvent or without solvent and then curing the mixture. This curing includes catalysts around room temperature, oxygen, and room temperature curing caused by humidity, heat curing, and photocuring caused by a catalyst caused by an acid generated by ultraviolet irradiation. In the present invention, the curing is not limited to these. You can

A curing accelerator may be used for this curing, if necessary. Specific examples of the curing accelerator include phosphorus-based compounds such as triphenylphosphine and tertiary amine-based compounds such as triethylamine, tetraethanolamine and 1,8-diaza-bicyclo [5,4,0] -7-.
Undecene (DBU), N, N-dimethylbenzylamine, 1,1,3,3-tetramethylguanidine, 2-ethyl-4-methylimidazole, N-methylpiperazine, etc., boron-based, for example, 1,8-diaza -Bicyclo [5,4,0] -7-undecenium tetraphenylborate and the like are used.

In the present invention, an epoxy resin composition containing the above-mentioned phenolic hydroxyl group-containing polyamide-polybutadiene-acrylonitrile block copolymer is further added to a polybutadiene-acrylonitrile copolymer having a functional group capable of reacting with an epoxy resin at both ends. By including a coalescence and curing the epoxy resin composition to form an island structure of this polybutadiene-acrylonitrile copolymer,
Further, the toughness of the epoxy resin can be improved. Although the reason for this is not yet clear, the phenolic hydroxyl group-containing polyamide-polybutadiene-acrylonitrile block copolymer promotes the formation of island structures in which the polybutadiene-acrylonitrile copolymer is more uniformly and finely dispersed in the epoxy resin. It is estimated to be because. Further, by forming an island structure in a state where the polybutadiene-acrylonitrile copolymer reacts with the epoxy resin, the toughness is further improved.

As the polybutadiene-acrylonitrile copolymer having a functional group capable of reacting with such an epoxy resin, a polybutadiene-acrylonitrile copolymer having amino groups at both ends, a polybutadiene-acrylonitrile copolymer having an epoxy group, A polybutadiene-acrylonitrile copolymer having a hydroxyl group, a polybutadiene-acrylonitrile copolymer having a vinyl group and the like can be used. Moreover, these can also be mixed and used as needed.

Although the epoxy resin composition of the present invention can be produced by the above method, other additives can be added to the composition, if necessary. For example, organic solvents such as toluene, ethanol, cellosolve, tetrahydrofuran, dimethylformamide, natural waxes, synthetic waxes and plasticizers such as metal salts of long-chain aliphatic acids, acid amides, esters, paraffins, etc. Release agents, stress relaxation agents such as nitrile rubber and butadiene rubber, chlorinated paraffin, bromtoluene, hexabromobenzene, flame retardants such as antimony trioxide, silane coupling agents, titanate coupling agents, aluminum cups Coupling agents such as ring agents, fused silica, crystalline silica,
Low α ray silica, glass flakes, glass beads, glass balloons, talc, alumina, calcium silicate, aluminum hydroxide, calcium carbonate, barium sulfate, magnesia, silicon nitride, boron nitride, ferrite, rare earth cobalt, gold, silver, Metallic powder such as nickel, copper, lead, iron powder, iron oxide, iron sand, graphite, carbon, valve stem, inorganic filler such as lead, or conductive particles, colorant such as dye or pigment, carbon fiber, glass Inorganic fibers such as fibers, boron fibers, silicon carbide fibers, alumina fibers, silica-alumina fibers, aramid fibers, polyester fibers, cellulose fibers, organic fibers such as carbon fibers, oxidation stabilizers, light stabilizers, improved moisture resistance Agents, thixotropic agents, diluents, defoamers, various other resins, tackifiers, antistatic agents, lubricants, UV absorbers, etc. It is also possible to focus.

The curable resin composition of the present invention can be used in various forms such as solid form, powder form, pace form, liquid form and sheet form, and can take a form according to the purpose of use. As applications of these, coils, capacitors, diodes, transistors, ICs, thermistors, resistors, liquid crystals, etc. for casting, molding,
Its usefulness is exhibited by using it for potting, sealing, bonding, coating, etc.

[0017]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto. Synthesis Example 1 Synthesis of a phenolic hydroxyl group-containing polyamide-polybutadiene acrylonitrile-block copolymer (phenolic hydroxyl group contained in the aramid portion is 2 mol%). Isophthalic acid 19.60 g (118 mmol), 3,4'-oxydianiline 26.4 g (132 mmol), 5-hydroxyisophthalic acid 0.41 g (2.3 mmol), lithium chloride 3.9 g, calcium chloride 12.1 g, N-
Methyl-2-pyrrolidone 240 ml, pyridine 54 ml
Was placed in a 1-liter 4-necked round bottom flask, and dissolved by stirring. Then, 74 g of triphenyl phosphite was added to
The reaction was carried out at 0 ° C. for 4 hours to generate a phenolic hydroxyl group-containing aramid oligomer body. In addition to this, a polybutadiene-acrylonitrile copolymer having carboxyl groups at both ends (Hycar CTBN, manufactured by BF Goodrich, polybutadiene-
The acrylonitrile component contained in the acrylonitrile part is 17 mol% and the molecular weight is about 3600) 48 g 240 m
1 pyridine solution was added and the reaction was continued for 4 hours and then cooled to room temperature. A polyamide-polybutadiene-acrylonitrile block copolymer containing about 2 mol% of 50 wt% phenolic hydroxyl groups was deposited. The precipitated polymer was further purified by washing with methanol and refluxing with methanol. The intrinsic viscosity of this polymer was 0.85 dl / g (dimethylacetamide, 30 ° C). Was measured infrared spectra of polymer powder by diffusion reflection method, the amide carbonyl group to 1674cm ^-1, C-H of the butadiene part in 2856-2975Cm ^-1
Absorption based on binding and absorption based on nitrile group at 2245 cm ^-1 were observed.

Synthesis Example 2 Phenolic hydroxyl group-containing polyamide-polybutadiene-
Synthesis of acrylonitrile block copolymer (14 mol% of phenolic hydroxyl group contained in aramid part). Isophthalic acid 19.93 g (120 mmol), 3,4'-oxydianiline 30.63 g (153 mmol), 5-
3.64 g (20 mmol) of hydroxyisophthalic acid,
Lithium chloride 3.9g, calcium chloride 12.1g, N
-Methyl-2-pyrrolidone 240 ml, pyridine 54 m
1 was placed in a 1-liter 4-necked round bottom flask, dissolved by stirring, and then 74 g of triphenyl phosphite was added,
The reaction was carried out at 90 ° C. for 4 hours to generate a phenolic hydroxyl group-containing aramid oligomer body. 25.5 g of polybutadiene-acrylonitrile copolymer having a carboxyl group at both ends (Hycar CTBN, manufactured by BF Goodrich, polybutadiene-acrylonitrile part contains 17 mol% of acrylonitrile component and molecular weight is about 3600)
A liquid dissolved in 40 ml of pyridine was added, and the reaction was further continued for 4 hours. Thereafter, the same post-treatment as in Synthesis Example 1 was performed to precipitate a polyamide-polybutadiene-acrylonitrile block copolymer containing about 14 mol% of phenolic hydroxyl groups used in the present invention. The intrinsic viscosity of this polymer was 0.82 dl / g (dimethylacetamide, 30 ° C). Was measured infrared spectra of polymer powder by diffusion reflection method, the amide carbonyl group 1675 cm ^-1, C-H of the butadiene part in 2854-2971Cm ^-1
Absorption based on binding and absorption based on nitrile group at 2243 cm ^-1 were observed.

Comparative Example 1 Bifunctional naphthalene type epoxy resin (EPICOLON HP-4032D
, Manufactured by Dainippon Ink and Chemicals, Inc., epoxy equivalent: 140)
100 g, triethanolamine which is a curing accelerator 1.
0 g and 33.6 g of 4,4'-diaminodiphenylmethane which is a curing agent were added, stirred and uniformly mixed to obtain a comparative epoxy resin composition.

Example 1 5 g of a phenolic hydroxyl group-containing aramid-polybutadiene-acrylonitrile block copolymer containing 2 mol% of the phenolic hydroxyl group obtained in Synthesis Example 1 was dissolved in 200 g of dimethylformamide, and then the bifunctional naphthalene was obtained. Type epoxy resin (EPICOLON HP-4032D, manufactured by Dainippon Ink and Chemicals, Inc., epoxy equivalent: 140) 95 g, and 0.1 g of triphenylphosphine which is a reaction accelerator,
The reaction was carried out at 0 ° C for 2 hours. This was added to water to precipitate the resin, which was repeatedly washed with warm water, and tetrahydrofuran was further added to azeotropically evaporate these solvents under pressure, followed by vacuum drying, and the polyamide resin was reacted with the epoxy resin. An epoxy resin composition containing the modified product was obtained. To a solution of 1 mg of this product in about 30 ml of pyridine, a color indicator of phenolic hydroxyl group (1 g of anhydrous iron (III) chloride was dissolved in 100 ml of chloroform, and 8 ml of pyridine was added).
Was added, and the precipitate was filtered to prepare a red solution), and a few drops were added and stirred, but no discoloration was observed, and all phenolic hydroxyl groups in this resin reacted with the glycidyl group. Then, it was confirmed that no unreacted phenol residue was contained. To 100 g of this epoxy resin composition, 4,4'-diaminodiphenylmethane 33.
6 g, 1.0 g of triethanolamine which is a curing accelerator
Was added to obtain an epoxy resin composition of the present invention.

Example 2 Phenolic hydroxyl group-containing aramid-polybutadiene-containing 14% by mole of the phenolic hydroxyl group obtained in Synthesis Example 2
5 g of acrylonitrile block copolymer, 95 g of the epoxy resin, and 0.1 g of triphenylphosphine as a reaction accelerator were dissolved in 200 g of dimethylformamide and reacted at 90 ° C. for 2 hours. This was added to water to precipitate the resin, which was repeatedly washed with warm water, and tetrahydrofuran was added to azeotrope these solvents under reduced pressure, followed by vacuum drying, and the epoxy resin reacted with the aramid part. An epoxy resin composition containing the modified product was obtained. By the same method as in Example 1, it was confirmed that all of the phenolic hydroxyl groups reacted with the glycidyl group and no unreacted phenol residue was contained. To 100 g of this epoxy resin composition, 3,4'-diaminodiphenylmethane 33.6 which is a curing agent was added.
g, and 1 g of triethanolamine, which is a curing accelerator, were melted, added, stirred and uniformly mixed to obtain an epoxy resin composition of the present invention.

Example 3 Phenolic hydroxyl group-containing aramid-polybutadiene-containing 14 mol% of the phenolic hydroxyl group obtained in Synthesis Example 2
Epoxy resin composition in which 5 g of acrylonotryl block copolymer and 95 g of the epoxy resin are dissolved in 150 ml of tetrahydroxyfuran solvent and then the tetrahydroxyfuran solvent is removed by a vacuum pump to uniformly mix the block copolymer with the epoxy resin. I got a thing. Bis (4-aminophenyl) methane 3 which is an epoxy resin curing agent is added to this composition.
3.6 g, sodium alcoholate 1 as a curing accelerator
g was dissolved and uniformly mixed to obtain an epoxy resin composition of the present invention.

Comparative Example 2 Tetrafunctional naphthalene type epoxy resin (EPICOLON EXA-4700
, Dainippon Ink and Chemicals, epoxy equivalent: 161) 1
00 g, triethanolamine 1.0 as a curing accelerator
g, and 29.2 g of 4,4′-diaminodiphenylmethane as a curing agent were added, and the mixture was stirred at 100 ° C. and uniformly mixed to obtain a comparative epoxy resin composition.

Example 4 5 g of the product obtained in Synthesis Example 1, 95 g of a tetrafunctional naphthalene type epoxy resin (EPICOLON EXA-4700, manufactured by Dainippon Ink and Chemicals, Inc., epoxy equivalent: 161), and a curing agent 4,4. ′
An epoxy resin composition of the present invention was obtained in the same manner as in Example 1 except that 29.2 g of diaminodiphenylmethane was used and this stirring and mixing was performed at 100 ° C.

Example 5 The procedure of Example 4 was repeated except that 5 g of polyamide-polybutadiene-acrylonitrile block copolymer containing about 14 mol% of phenolic hydroxyl groups obtained in Synthesis Example 2 was used. An epoxy resin composition was obtained.

Comparative Example 3 In Comparative Example 1, 100 g of the epoxy resin composition had polybutadiene-acrylonitrile copolymer having carboxyl groups at both ends (Hycar CTBN, manufactured by BF Goodrich, polybutadiene-acrylonitrile containing 17 mol% of acrylonitrile). Then, 20 g of a molecular weight of about 3600) was further added, stirred and uniformly mixed to obtain a comparative epoxy resin composition containing a polybutadiene-acrylonitrile copolymer.

Example 6 100 g of the epoxy resin composition obtained in Example 2 had a polybutadiene-acrylonitrile copolymer having a carboxyl group at both ends (Hycar CTBN, manufactured by BF Goodrich, polyacrylonitrile-acrylonitrile part containing 17 acrylonitrile). Epoxy resin composition of the present invention containing polybutadiene-acrylonitrile copolymer and polyamide-polybutadiene-acrylonitrile block copolymer, which are rubber components, in the same manner except that 20 g of mol% and a molecular weight of about 3600) were further added. Got

Comparative Example 4 In Comparative Example 2, 100 g of the epoxy resin composition had polybutadiene-acrylonitrile copolymer having carboxyl groups at both ends (Hycar CTBN, manufactured by BF Goodrich, polybutadiene-acrylonitrile containing 17 mol% of acrylonitrile). Then, 20 g of a molecular weight of 3600) was further added, stirred and uniformly mixed to obtain a comparative epoxy resin composition containing a polybutadiene-acrylonitrile copolymer.

Example 7 The procedure of Example 6 was repeated except that the epoxy resin composition obtained in Example 5 was used instead of the epoxy resin composition, and a polybutadiene-acrylonitrile block copolymer and a polyamide-polybutadiene-acrylonitrile block copolymer were used. An epoxy resin composition of the invention was obtained.

After molding the epoxy resin compositions of Comparative Examples 1 to 4 and Examples 1 to 6 described above, at 80 ° C. for 3 hours and 120 ° C.
It was heated for 6 hours to prepare a test piece. Bending strength was measured by the following method using this sample piece, and the obtained results are shown in Table 1.
Summarized in. Flexural strength measurement: Specimen according to ASTM D790: 63.5
The measurement was performed with a size of × 12.7 × 2 (mm).

[0031]

[Table 1]

Claims (3)

(57) [Claims] 1. An epoxy resin composition comprising a polyfunctional naphthalene type epoxy resin, a curing agent and a phenolic hydroxyl group-containing polyamide-polybutadiene-acrylonitrile copolymer. 2. A polyfunctional naphthalene type epoxy resin, a curing agent, and a phenolic hydroxyl group-containing polyamide-polybutadiene-acrylonitrile copolymer are contained, and a part of the polyfunctional naphthalene type epoxy resin is a phenolic hydroxyl group-containing polyamide-polybutadiene. An epoxy resin composition characterized by reacting with an acrylonitrile copolymer to form a modified epoxy resin. 3. The epoxy resin composition according to claim 1, further comprising a polybutadiene-acrylonitrile copolymer having a functional group capable of reacting with an epoxy resin at both ends, and a cured product of the epoxy resin composition. The epoxy resin composition according to claim 1, which is present as an island structure.