JP2823056B2 - Epoxy resin composition and cured product thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition which gives a cured product having excellent moisture resistance and toughness, and more particularly to an epoxy resin composition suitably used in the field of electric and electronic parts and as a composite material, and its curing. About things.

[0002]

2. Description of the Related Art Epoxy resins are widely used in the fields of electric and electronic parts due to their excellent electrical properties, heat resistance, mechanical properties and adhesiveness.

[0003] However, in recent years, particularly with the development of the electric and electronic fields, higher performance epoxy resins have been demanded. For example, I. C. In order to achieve high density and high integration, not only heat resistance but also high moisture resistance and further toughness have been required for a cured product of a resin used as a sealing material. For example, I. C. For surface mount devices of
It is immersed in a solder bath at 0 ° C. or higher. At this time, cracks are caused by rapid evaporation of moisture contained in the cured product, and therefore, crack resistance is strongly required.

[0004] Therefore, many proposals have been made for epoxy resins and compositions thereof. For example, JP-A-63-2
The epoxidized polyphenol described in No. 646 gives a cured product having excellent heat resistance. However, all of the cured products of the epoxidized products lack toughness and moisture resistance. Particularly, those obtained by increasing the crosslink density and increasing the heat resistance have significantly reduced toughness and moisture resistance.

[0005]

SUMMARY OF THE INVENTION The present invention is to provide a resin composition which provides a cured product realizing high moisture resistance and toughness capable of withstanding increasingly severe conditions, and a cured product thereof. is there.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to obtain a cured product of an epoxy resin having high moisture resistance and toughness, which cannot be obtained with a conventional epoxy resin composition. Using the epoxy resin composition of
The inventors have found that the moisture resistance and toughness of the cured product are significantly improved, and have completed the present invention.

That is, the present invention provides: (A) Formula (1)

[0008]

Wherein X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group or a halogen atom, and (B) a formula (2)

[0010]

A phenol aralkyl novolak resin represented by the formula: wherein the average value of n is a value of 0 to 15;
And (C) an epoxy resin composition characterized by containing a curing accelerator.

2. (A ') Equation (3)

[0013]

Wherein X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group or a halogen atom, and a dimethylol compound represented by the formula (4):

[0015]

An epoxide of a naphthol reactant represented by the formula (1), wherein the epoxy resin contains 30% by weight or more of the epoxy compound of the formula (1) of the above item (1); An epoxy resin composition comprising: a phenol aralkyl novolak resin; and (C) a curing accelerator.

3. 3. A cured product of the epoxy resin composition according to the above item 1 or 2.

The epoxy resin composition of the present invention has good moldability and gives a cured product having excellent moisture resistance and toughness.

Hereinafter, the present invention will be described in detail. Equation (1)
In the compound X, examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group. And a methyl group and a t-butyl group are particularly preferable. As the aryl group, a phenyl group, 4
Examples thereof include a -methylphenyl group and a 2-methylphenyl group, and a phenyl group is particularly preferable. Examples of the halogen atom include a chlorine atom, a fluorine atom, a bromine atom and an iodine atom, and a chlorine atom and a bromine atom are particularly preferable.

The compound of the formula (1) and the epoxy resin containing 30% by weight or more thereof can be produced as follows. That is, it can be produced by subjecting the compound represented by the formula (3) and the naphthol represented by the formula (4) to dehydration condensation in the presence of an acid catalyst, followed by epoxidation.

As the dimethylol compound represented by the formula (3), a 4-methylphenol dimethylol compound,
-Ethylphenol dimethylol compound, 4-n-propylphenol dimethylol compound, 4-i-propylphenol dimethylol compound, 4-n-butylphenol dimethylol compound, 4-sec-butylphenol dimethylol compound, 4-t-butylphenol Alkylphenol dimethylol compound such as dimethylol compound, 4-phenylphenol dimethylol compound, or 4-fluorophenol dimethylol compound;
Examples include, but are not limited to, halogen-substituted phenol dimethylol compounds such as chlorophenol dimethylol compound and 4-bromophenol dimethylol compound.

The naphthol represented by the formula (4) includes 1-naphthol and 2-naphthol.

As the acid catalyst, hydrochloric acid, sulfuric acid, phosphoric acid, p
-Toluenesulfonic acid, oxalic acid and the like can be used, and the acid catalyst is preferably used in an amount of 0.1 to 30% by weight of the compound represented by the formula (3). In addition, naphthol is preferably used in an amount of 2 to 15 times by mole the compound represented by the formula (3).

The reaction can be carried out without a solvent in a solvent such as benzene, toluene, methyl isobutyl ketone, or the like. The reaction temperature is preferably in the range of 20 to 150 ° C.
After completion of the reaction, the used catalyst is removed by washing with water or the like, and the solvent and excess naphthol are distilled off under reduced pressure to obtain a dehydrated condensate.

Next, the dehydration condensate thus obtained is added to the formula (5)

[0026]

(Wherein X represents a halogen atom) by reacting an epihalohydrin compound represented by the formula (1) in the presence of a basic compound to obtain an epoxy resin containing the compound represented by the formula (1) in an amount of 30% by weight or more. Can be easily obtained.

In the above formula (5), examples of the halogen atom represented by X include Cl, Br, I and the like.
Specific examples of the compound include epichlorohydrin,
Epibromhydrin, epiiodohydrin and the like can be mentioned, and a mixture thereof can be used, but epichlorohydrin is preferably used industrially.

The reaction between the dehydration condensate and the epihalohydrin compound can be carried out by a known method.

For example, the dehydration condensate and an epihalohydrin compound in an excess molar amount with respect to the hydroxyl equivalent are
The reaction is carried out in the presence of a quaternary ammonium salt such as tetramethylammonium chloride, tetramethylammonium bromide or triethylammonium chloride or an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide to form a quaternary ammonium salt or the like. When used, the reaction stops at the stage of the ring-opening addition reaction, and then the above alkali metal hydroxide is added to cause a ring-closing reaction.

When the reaction is carried out by adding an alkali metal hydroxide from the beginning, a ring-opening addition reaction and a ring-closing reaction are performed at once.

The proportion of the epihalohydrin compound used is usually in the range of 1 to 50 mol, preferably 3 to 15 mol, per 1 hydroxyl equivalent of the dehydrated condensate.

At this time, to make the reaction proceed smoothly,
Alcohols such as methanol, or aprotic polar solvents such as acetone or dimethylsulfoxide, dimethylsulfone and dimethylformamide can be used, and dimethylsulfoxide is particularly preferable.

The alkali metal hydroxide can be added in the form of an aqueous solution or in a solid state. The amount of the alkali metal hydroxide to be used is usually 0.8 to 1.5 with respect to 1 hydroxyl equivalent of the dehydrated condensate.
Mol, preferably in the range of 0.9 to 1.3 mol. When the quaternary ammonium salt is used, the amount of the quaternary ammonium salt is usually 0.001 to 1 with respect to the hydroxyl equivalent 1 of the dehydration condensate.
Mole, preferably in the range of 0.005 to 0.5 mole. The reaction temperature is usually 30 to 130 ° C., preferably 40 to 1
20 ° C.

The reaction can be allowed to proceed while removing the water produced by the reaction outside the reaction system. After the reaction is completed, salts produced as by-products are removed by washing with water, filtration and the like, and an excess epihalohydrin compound is distilled off to obtain an epoxy resin containing the compound represented by the formula (1) in an amount of 30% by weight or more.

The epoxy resin thus obtained is
The compound represented by the formula (1) is contained in an amount of 30% by weight or more, preferably 35% by weight or more.

Hereinafter, the epoxy resin composition of the present invention will be described. Compound of formula (1) or 30% by weight thereof
The above-mentioned epoxy resin can be used alone or in combination with another epoxy resin. When used in combination, the proportion of the compound of formula (1) or the epoxy resin containing 30% by weight or more of the compound to the total epoxy resin is 30% by weight.
The above is preferable, and especially 50% by weight or more is preferable.

As other epoxy resins to be used in combination, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, alicyclic epoxy resin, biphenyl type epoxy resin and the like can be used. Epoxy resins are advantageous in terms of heat resistance. For example, a cresol novolak type epoxy resin, a phenol novolak type epoxy resin, a brominated phenol novolak type epoxy resin and the like are exemplified, but not limited thereto. These may be used alone or in combination of two or more.

In the phenol aralkyl novolak resin represented by the formula (2), the average value of n is preferably from 2 to
12, more preferably 5 to 10. If the value of n is too large, the viscosity rises and causes a problem in workability. Examples of the phenol aralkyl novolak resin of the formula (2) include “Mirex XL” series resin manufactured by Mitsui Toatsu Chemicals, Inc.

The phenol aralkyl novolak resin (curing agent) of the formula (2) can be used alone or in combination with another curing agent. When used in combination, the proportion of the phenol aralkyl novolak resin of the formula (2) in the total curing agent is preferably at least 30% by weight, particularly preferably at least 50% by weight.

Other curing agents used in combination include, for example,
Polyamine-based curing agents such as aliphatic polyamines, aromatic polyamines and polyamide polyamines; acid anhydride-based curing agents such as hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride; phenol-based curing agents such as phenol novolak and cresol novolac; Examples thereof include, but are not limited to, Lewis acids such as boron fluoride or salts thereof, and curing agents such as dicyandiamides. These may be used alone or in combination of two or more.

In the epoxy resin composition of the present invention, the amount of the phenol aralkyl novolak resin of the formula (2) used is one equivalent of the epoxy compound of the formula (1) or one equivalent of the epoxy resin containing 30% by weight or more of the epoxy compound. for,
Preferably 0.3 to 2 equivalents, more preferably 0.5 to
1.5 equivalents. When another epoxy resin and / or another curing agent is used in combination, the total amount of the curing agent used is preferably 0.3 to 2 equivalents to 1 equivalent of the epoxy group in the total amount of the epoxy compound and the epoxy resin. More preferably 0.5
１．５1.5 equivalents.

As a curing accelerator for smoothly conducting a curing reaction, any of those used for ordinary epoxy resins can be used, and examples thereof include 2-methylimidazole and 2-ethyl-4-methylimidazole. , Imidazoles such as 2-phenylimidazole, benzyldimethylamine, 2,4,6-tris (dimethylaminomethyl)
Tertiary amines such as phenol, phosphines such as triphenylphosphine and salts thereof, 1,8 diazabicyclo (5,4,0) undecene-7 (DBU) and salts thereof,
Aluminum compounds, titanium compounds and the like can be mentioned. The amount used is preferably from 0.01 to 10 parts by weight, more preferably from 0.5 to 2 parts by weight, based on 100 parts by weight of the total amount of the epoxy compound and the epoxy resin used. If the amount of the curing accelerator is too large, the time until gelation is short, which may cause a problem in workability. If the amount is too small, a problem of insufficient curing may occur.

The epoxy resin composition of the present invention may contain, as optional components, various compounding agents such as a flame retardant, an inorganic or organic filler, a surface treating agent such as a silane coupling agent, a release agent, and a pigment. Can be added. The epoxy resin composition of the present invention is prepared by uniformly mixing and kneading the components by means of a mixer, roll, kneader or the like. Pre-curing of the epoxy resin composition of the present invention is possible as long as it is equal to or higher than the softening temperature of the composition.
At a temperature of The curing time varies greatly depending on the amount, type and curing temperature of the curing accelerator, but is usually in the range of 30 to 300 seconds using a transfer molding machine. The obtained pre-cured product does not have sufficient heat resistance for practical use because of insufficient curing, and is usually post-cured at 170 to 180 ° C. for 4 to 8 hours.

Since the cured product obtained from the epoxy resin composition of the present invention exhibits toughness and high moisture resistance, it is suitable for electric and electronic parts, particularly for sealing materials, insulating materials and laminates.

[0046]

The present invention will be specifically described below based on examples and comparative examples. Synthesis Example 1 162 g (1.5 mol) of paracresol, 90 g (3 mol) of paraformaldehyde and 100 ml of water were charged into a 1-liter flask equipped with a thermometer, a condenser, a dropping funnel and a stirrer, and stirred under a nitrogen atmosphere. At room temperature, 120 g of a 15% aqueous sodium hydroxide solution (0.45 mol as sodium hydroxide) was added at room temperature while paying attention to heat generation.
The solution was slowly dropped so as not to exceed 0 ° C. Thereafter, the mixture was heated to 50 ° C. in an oil bath and reacted for 10 hours. After completion of the reaction, 300 ml of water was added and the mixture was cooled to room temperature, neutralized with a 10% aqueous hydrochloric acid solution while paying attention to heat generation, and then the precipitated crystals were collected by filtration. The filtrate was washed with water until it became neutral, and the crystals were dried under reduced pressure (100 mmHg at 50 ° C to give white crystals (A1) 2).
02 g was obtained.

168 g (1.0 mol) of this white crystal (A1) and 576 g (4.0 mol) of 1-naphthol were charged into a glass vessel equipped with a warm clock and a stirrer, and 1500 ml of methyl isobutyl ketone was added as a solvent. While stirring at room temperature under a nitrogen atmosphere, 1.7 g of P-toluenesulfonic acid was gradually added to the mixture while paying attention to heat generation so that the liquid temperature did not exceed 50 ° C. After the addition, warm to 50 ° C on an oil bath and add 2
After reacting for an hour, 500 ml of methyl isobutyl ketone was added, and the mixture was transferred to a separating funnel and washed with water until the washing water became neutral. After washing with water, the organic layer was concentrated under reduced pressure to obtain 368 g of a pale yellow viscous substance (A2). The softening temperature of the product (A2) (measured by a ring and ball method according to JIS K2425) was 117 ° C. and the hydroxyl equivalent (g / mol) was 137.

137 g of the product (A2) was transferred to a 1-liter reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, and a product water separator, and then 460 g of epichlorohydrin was charged and replaced with nitrogen. 85 g of a 48% aqueous sodium hydroxide solution was added dropwise over 5 hours. During the dropwise addition, the produced water and water of the aqueous sodium hydroxide solution were continuously removed from the reaction system by azeotropic distillation with epichlorohydrin at a reaction temperature of 60 ° C. under a reduced pressure of 100 to 150 mmHg, and epichlorohydrin was returned to the system. Then, after recovering excess unreacted epichlorohydrin under reduced pressure, 500 ml of methyl isobutyl ketone was added, and the mixture was washed with 100 ml of water until the aqueous layer became neutral. The methyl isobutyl ketone was removed from the methyl isobutyl ketone layer under reduced pressure, and a pale yellow viscous substance (A3) 1
72 g were obtained. The product (A3) is an epoxy resin having a softening temperature of 89 ° C. and an epoxy equivalent (g / mol) of 215,
The compound represented by the formula (1) (where X is a methyl group) is
It was confirmed by mass spectrum that the content was contained by weight.

Synthesis Example 2 222 g (1.5 mol) of 4-t-butylphenol, 90 g (3 mol) of paraformaldehyde and 100 ml of water were equipped with a thermometer, a cooling tube, a dropping funnel and a stirrer.
The mixture was charged into a liter flask, and stirred while blowing nitrogen. 15% aqueous sodium hydroxide solution 120 at room temperature
g (0.45 mol as sodium hydroxide) was slowly added dropwise while paying attention to heat generation so that the liquid temperature did not exceed 50 ° C. Thereafter, the reaction was carried out at 50 ° C. for 10 hours in a water bath.
After completion of the reaction, 300 ml of water was added, the mixture was cooled to room temperature, and neutralized with a 10% hydrochloric acid aqueous solution while paying attention to heat generation. The oil layer was separated by adding 500 ml of chloroform, washed with a water-methanol solution (water: methanol = 80/20 (% by weight)), and dried by adding anhydrous sodium sulfate. Subsequently, chloroform was removed under reduced pressure to obtain 256 g of a yellow-green sticky liquid (B1).

254 g of the liquid (B1) thus obtained was placed in a glass container equipped with a warm clock and a stirrer, and further 1 g of the liquid (B1) was added.
576 g of naphthol and 15 methyl isobutyl ketone
After adding 00 ml, the mixture was stirred at room temperature under a nitrogen atmosphere.
Then, 1.7 g of p-toluenesulfonic acid was gradually added so that the liquid temperature did not exceed 50 ° C. while paying attention to heat generation. After the addition, the mixture was reacted at 50 ° C. for 2 hours in a hot water bath, then transferred to a separating funnel and washed with water. After washing with water until the washing water became neutral, the solvent and unreacted substances were removed from the organic layer under reduced pressure to obtain 414 g of a product (B2). The softening temperature (JIS K2425 ring and ball type) of the product (B2) was 121 ° C., and the hydroxyl equivalent (g / mol) was 151.

In Synthesis Example 1, 151 g of the above product (B2) was used in place of the product (A2), and epoxidation was carried out in the same manner as in the other cases to obtain 186 g of a product (B3). The product (B3) is an epoxy resin having a softening temperature of 89 ° C. and an epoxy equivalent (g / mol) of 240, and contains 35% by weight of a compound represented by the formula (1) (where X is a t-butyl group). Was confirmed by mass spectrum.

Synthesis Example 3 193 g (1.5 mol) of 4-chlorophenol, 90 g (3 mol) of paraformaldehyde and 100 ml of water were charged into a 1-liter flask equipped with a thermometer, a condenser, a dropping funnel and a stirrer. The mixture was stirred while blowing nitrogen. 120 g of a 15% aqueous sodium hydroxide solution at room temperature
(0.45 mol as sodium hydroxide) was slowly added dropwise while paying attention to heat generation so that the liquid temperature did not exceed 50 ° C. Thereafter, the reaction was carried out at 50 ° C. for 10 hours in a water bath. After completion of the reaction, 300 ml of water was added, the mixture was cooled to room temperature, and neutralized with a 10% hydrochloric acid aqueous solution while paying attention to heat generation. Thereafter, the precipitated crystals were collected by filtration, washed until the pH of the filtrate became 6 to 7, and dried under reduced pressure (10 mmHg) at 50 ° C. to obtain white crystals (C
1) 226 g was obtained.

The white crystal (C1) 189 thus obtained was obtained.
g in a glass container equipped with a warm watch and a stirrer, 576 g of 1-naphthol and 1500 ml of methyl isobutyl ketone were added, and the mixture was stirred at room temperature under a nitrogen atmosphere. Then, 1.7 g of p-toluenesulfonic acid was gradually added so that the liquid temperature did not exceed 50 ° C. while paying attention to heat generation. After the addition, the mixture was reacted at 50 ° C. for 2 hours in a hot water bath, then transferred to a separating funnel and washed with water. After washing with water until the washing water showed neutrality, the solvent and unreacted substances were removed from the organic layer under reduced pressure to obtain 388 g of a product (C2). The softening temperature (JIS K2425 ring and ball type) of the product (C2) was 118 ° C. and the hydroxyl equivalent (g / mol) was 142.

In Synthesis Example 1, epoxidation was carried out in the same manner as in Synthesis Example 1 except for using 142 g of the above product (C2) in place of the product (A2) to obtain 176 g of a product (C3). The product (C3) is an epoxy resin having a softening temperature of 95 ° C. and an epoxy equivalent (g / mol) of 230, and contains 37% by weight of a compound represented by the formula (1) (where X is a chlorine atom). , And mass spectra.

Synthesis Example 4 255 g (1.5 mol) of 4-phenylphenol, 90 g (3 mol) of paraformaldehyde and 100 ml of water were charged into a 1-liter flask equipped with a thermometer, a condenser, a dropping funnel and a stirrer. The mixture was stirred while blowing nitrogen.
At room temperature, 120 g of a 15% aqueous sodium hydroxide solution (0.45 mol as sodium hydroxide) was slowly added dropwise while paying attention to heat generation so that the liquid temperature did not exceed 50 ° C.
Thereafter, the mixture was heated to 50 ° C. in a water bath and reacted for 20 hours. After completion of the reaction, 300 ml of water was added, the mixture was cooled to room temperature, and neutralized with a 10% aqueous hydrochloric acid solution while paying attention to heat generation. 500 ml of chloroform was added thereto to separate an oil layer, which was washed with a water-methanol aqueous solution [water: methanol = 80: 20 (% by weight)], and dried by adding anhydrous sodium sulfate. Subsequently, chloroform was removed under reduced pressure to obtain 305 g of a yellow viscous liquid (D1).

The viscous liquid (D1) 295 thus obtained was obtained.
g in a glass vessel equipped with a warm watch and a stirrer, 576 g of 1-naphthol and 1500 ml of methyl isobutyl ketone were added, and the mixture was stirred at room temperature under a nitrogen atmosphere. Then, 1.7 g of p-toluenesulfonic acid was gradually added so that the liquid temperature did not exceed 50 ° C. while paying attention to heat generation. After the addition, the mixture was heated to 50 ° C. in an oil bath and reacted for 2 hours.
It was transferred to a separating funnel and washed with water. After washing with water until the washing water shows neutrality, the solvent and unreacted substances are removed from the organic layer under reduced pressure,
415 g of product (D2) were obtained. The softening temperature (JIS K2425 ring and ball method) of the product (D2) was 128 ° C. and the hydroxyl equivalent (g / mol) was 159.

In Synthesis Example 1, epoxidation was carried out in the same manner as in Synthesis Example 1 except that 159 g of the above product (D2) was used in place of the product (A2), and 194 g of a product (D3) was obtained. The product (D3) is an epoxy resin having a softening temperature of 95 ° C. and an epoxy equivalent (g / mol) of 233, and contains 42% by weight of a compound represented by the formula (1) (where X is a phenyl group). , And mass spectra.

Synthesis Example 5 94 g (1.0 mol) of phenol and 97 g (0.7 mol) of p-xylene glycol were charged into a 500 ml flask equipped with a thermometer, a condenser and a stirrer, and charged under a nitrogen atmosphere.
1.0 g of p-toluenesulfonic acid while stirring at 0 ° C.
Was added slowly paying attention to heat generation. Then, on an oil bath,
The mixture was heated to 0 ° C. and reacted for 6 hours. After completion of the reaction, 250 ml of methyl isobutyl ketone was added to the reaction solution, and the mixture was transferred to a separating funnel and washed with water until the washing water became neutral. After washing with water, methyl isobutyl ketone was removed under reduced pressure to obtain 143 g of a product (E) represented by the formula (2). The softening temperature of the product (E) (measured by the ring and ball method according to JIS K2425) was 89.8 ° C., the hydroxyl equivalent (g / mol) was 180, and the average value of n in the formula (2) was 7.9.

Examples 1 to 5 and Comparative Example 1 The components were blended at the ratios shown in Table 1 and uniformly kneaded with a roll kneader heated to 70 ° C. Thereafter, the mixture was cooled, pulverized by a pulverizer, and further tableted by a tablet machine to obtain a molding material. The tablet was preheated by a high frequency preheater, pressed and molded at 150 ° C. for 200 seconds using a transfer molding machine, and further molded at 160 ° C. for 2 hours and at 180 ° C. for 6 hours in an oven. To obtain a cured molded article test piece. Table 1 shows the results of measuring the moisture absorption rate, bending strength and breaking energy by a bending tester using this test piece.

The measurement conditions are as follows. (Moisture Absorption Rate) The weight increase rate after standing at 121 ° C. in a 100% atmosphere for 24 hours was determined. The test piece has the dimensions shown in JIS K-6911. (Bending strength and breaking energy) Based on JIS K-6911, the flexural modulus at 30 ° C,
The bending strength was measured, and the fracture energy was determined from the results.

[0061]

[0062]

The epoxy resin composition of the present invention provides an epoxy cured product having not only excellent toughness and mechanical properties but also high moisture resistance, and is extremely useful in industry.

Continuation of the front page (56) References JP-A-59-105018 (JP, A) JP-A-3-717 (JP, A) JP-A-3-163128 (JP, A) JP-A-3-220219 (JP) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C08G 59/32 C08G 59/06 C08G 59/62 H01L 23/29

Claims (3)

(57) [Claims] (A) Equation (1) (Wherein, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group or a halogen atom). (B) Formula (2) (In the formula, the average value of n is a value of 0 to 15.) An epoxy resin composition comprising: a phenol aralkyl novolak resin represented by the following formula: and (C) a curing accelerator. (A ') Equation (3) (Wherein X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group or a halogen atom), and a formula (4) An epoxide of a reaction product of naphthol represented by the formula: wherein the epoxy compound of the formula (1) of claim 1 is 30% by weight.
An epoxy resin composition comprising: an epoxy resin containing the above; (B) a phenol aralkyl novolak resin of the formula (2) according to claim 1; and (C) a curing accelerator. 3. A cured product of the epoxy resin composition according to claim 1 or 2.