JPH0827052A - Polyphenol, epoxy resin, epoxy resin composition and its cured material - Google Patents

Abstract

PURPOSE:To provide a polyphenol and an epoxy resin capable of producing a cured material excellent in heat resistance, water resistance and mechanical strength and useful as a molding material, a coating material, etc. CONSTITUTION:A polyphenol compound of formula I (P and R are each H, a halogen, a 1 to 8C alkyl or an aryl; Q is a 1 to 3C alkyl), e.g. a compound of formula II. The compound of formula I can be synthesized, e.g. by conducting condensation reaction between a compound of formula III and a phenol in the presence of an acid catalyst. In addition, if the compound of formula I is reacted with an epihalohydrin in the presence of an alkaline metal hydroxide, an epoxy resin of formula IV (G is glycidyl) can be synthesized. An epoxy resin composition prepared by using a polyphenol compound of formula I and/or an epoxy resin of formula IV as the essential components can produce a cured material more excellent in heat resistance, water resistance and mechanical resistance than the conventional general-purpose epoxy resin composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin curing agent or an epoxy resin and an epoxy resin composition which give a cured product excellent in heat resistance, water resistance and mechanical strength, and a cured product thereof.

[0002]

2. Description of the Related Art Heretofore, in the field of electric / electronic parts, particularly IC sealants, epoxy resin compositions containing an epoxy resin, a phenol novolac resin and a curing accelerator as main components have been widely used. The high density and high integration of ICs in recent years have required the sealants to have high heat resistance and low water absorption. In particular, the harsh condition of immersion in a solder bath in high-density mounting of ICs further increases the requirements for cured products with high heat resistance, low water absorption, and high toughness.

However, in the conventional epoxy resin composition, the cresol novolac type epoxy resin generally used as an epoxy resin has high heat resistance, but has a drawback that it is inferior in terms of water absorption and toughness.

On the other hand, the phenol novolac resin which is generally used as a curing agent is still insufficient in heat resistance and does not give satisfactory results under the above-mentioned conditions which become more and more severe. Therefore, development of a resin that gives a cured product having heat resistance, low water absorption, and high toughness has been awaited.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a resin, a resin composition and a resin and resin composition which give a cured product having high heat resistance, low water absorption and high toughness which can withstand such severe conditions. It provides a cured product.

[0006]

In view of these circumstances, the present inventors have earnestly studied for an epoxy resin which gives a cured product having excellent heat resistance, water resistance and mechanical strength, and as a result, have a specific molecular structure. A polyphenol compound and an epoxy resin obtained by epoxidizing the same,
The inventors have found that the cured product imparts excellent heat resistance, water resistance and mechanical strength, and completed the present invention.

That is, the present invention is based on the equation (1)

Embedded image

(In the formula (1), P and R each represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group, and each P and R may be the same or different. And Q represents an alkyl group having 1 to 3 carbon atoms),

Equation (2) Equation (2)

[Chemical 4]

(In the formula (2), P, R and Q have the same meanings as in the formula (1), and G represents a glycidyl group.)
(3) (a) Epoxy resin (b) Epoxy resin composition containing the polyphenol compound of formula (1) described in (1) above, (4) (a) above ( 2) An epoxy resin composition containing the epoxy resin of the formula (2) described in (2) (b) a curing agent,

(5) (a) Epoxy resin of the formula (2) described in the above (2) (b) Epoxy resin composition containing the polyphenol compound of the formula (1) described in the above (1), 6) The epoxy resin composition according to the above (3), (4) or (5) containing a curing accelerator, (7) The epoxy resin according to the above (3), (4), (5) or (6). A cured product obtained by curing a composition is provided.

The compound represented by the formula (1) is represented by, for example, the formula (3)

[0013]

Embedded image

(In the formula (3), P and Q have the same meanings as in the formula (1).)

It can be obtained by subjecting a compound represented by and a phenol to a condensation reaction in the presence of an acid catalyst.

The compound represented by the formula (2) can be obtained by reacting the compound represented by the formula (1) with epihalohydrin in the presence of an alkali metal hydroxide.

The compound represented by the formula (3) is J.Org.Chem.1
986,51 (14), 2627-37, Eur.Pat.Appl / EP199,661 and the like, as well as those obtained by any known method can be used.

Examples of the alkyl group represented by Q in the formulas (1) to (3) include a methyl group, an ethyl group and a propyl group, and a methyl group and an ethyl group are preferable.

Here, the phenols are compounds having at least one phenolic hydroxyl group, and examples thereof include phenol, cresol, ethylphenol, n-propylphenol, isobutylphenol, t-butylphenol, octylphenol, nonylphenol, xylenol, methyl. Various o-, m-, p- isomers of alkylphenol represented by butylphenol, di-t-butylphenol, etc., or vinylphenol,
Various o-m-p-isomers of allylphenol, propenylphenol, ethynylphenol, or cycloalkylphenol typified by cyclopentylphenol, cyclohexylphenol, cyclohexylcresol, or substituted phenols such as phenylphenol, or α-naphthol. , Β-naphthol and other naphthols. These phenols are 1
Only one kind may be used, or two or more kinds may be used in combination.

When carrying out the condensation reaction, the amount of phenols used is preferably in the range of 4 to 30 mol, particularly preferably 5 to 25 mol, per 1 mol of the compound represented by the formula (3).

An acid catalyst is preferably used in the above condensation reaction, and various acid catalysts can be used, but hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, oxalic acid, boron trifluoride, anhydrous aluminum chloride, chloride Zinc and the like are preferable, and p-toluenesulfonic acid, sulfuric acid, hydrochloric acid and the like are particularly preferable. When using a gas such as hydrogen chloride that is in a gas state at room temperature, the reaction may be performed while blowing the gas into the reaction mixture. The amount of these acid catalysts used is not particularly limited, but is not limited to the formula (3).
0.001 to 0.1 based on the amount of the compound represented by
It can be selected in a double molar range. At this time, as a co-catalyst, methyl mercaptan, methyl mercaptoacetic acid,
You may add n-dodecyl mercaptan etc. in the reaction mixture. The amount of these co-catalysts used is not particularly limited, but it can be used in a range of 0.01 to 10 times the molar amount of the acid catalyst used.

The condensation reaction can be carried out without a solvent or in the presence of an organic solvent. Specific examples of the case of using an organic solvent include toluene, xylene, and methyl isobutyl ketone. The amount of the organic solvent used is preferably 50 to 300% by weight, and particularly preferably 100 to 250% by weight, based on the total weight of the raw materials charged. The reaction temperature is preferably 20 to 200 ° C, particularly preferably 25 to 190 ° C. The reaction time is preferably 3 to 30 hours, particularly preferably 5 to 25 hours.

After completion of the reaction, neutralization or washing is carried out to adjust the pH value to 3 to 7, preferably 5 to 7. When washing with water, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, ammonia, sodium dihydrogen phosphate and diethylenetriamine and trihydrate. Various basic substances such as organic amines such as ethylene tetramine, aniline and phenylenediamine may be used as the neutralizing agent for treatment. In the case of washing with water, it may be carried out according to a conventional method. For example, water in which the above-mentioned neutralizing agent is dissolved is added to the reaction generation system, and the liquid separation and extraction operation is repeated.

After the neutralization treatment, unreacted phenols and solvent are distilled off under reduced pressure heating to concentrate the product,
The polyphenol compound of the present invention represented by the formula (1) (hereinafter, simply referred to as polyphenol compound unless otherwise specified) can be obtained.

As a method for obtaining the epoxy resin of the present invention represented by the formula (2) from a polyphenol compound, a known method can be adopted. For example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is added to a dissolved mixture of the obtained polyphenol compound and an excess of epihalohydrin such as epichlorohydrin or epibromhydrin, or at 20 to 120 ° C. while being added. 0.5 at temperature
The epoxy resin of the present invention can be obtained by reacting for 10 hours.

In the reaction for obtaining the epoxy resin of the present invention, an aqueous solution of the alkali metal hydroxide may be used, in which case an aqueous solution of the alkali metal hydroxide is continuously added to the reaction mixture. A method may be used in which water and epihalohydrin are continuously flowed out under reduced pressure or normal pressure, and liquid separation is performed to remove water and epihalohydrin is continuously returned to the reaction system.

Further, a quaternary ammonium salt such as tetramethylammonium chloride, tetramethylammonium bromide or trimethylbenzylammonium chloride is added as a catalyst to a dissolved mixture of a polyphenol compound and epihalohydrin, and the mixture is added at 0.5 to 5 at 50 to 150 ° C.
The solid or aqueous solution of the alkali metal hydroxide exemplified above is added to the halohydrin ether compound obtained by the reaction for a period of time, and the mixture is again reacted at a temperature of 20 to 120 ° C. for 0.5 to 10 hours to dehydrohalogenate (ring closure ) May be used.

Usually, the amount of epihalohydrin used in these reactions depends on the hydroxyl group of the polyphenol compound.
It is usually 1 to 20 mol, preferably 2 to 10 mol, based on the equivalent amount. The amount of the alkali metal hydroxide used is 0.8 to 15 mol, preferably 0.9 to 11 mol, based on 1 equivalent of the hydroxyl group of the polyphenol compound. Further, in order to allow the reaction to proceed smoothly, it is preferable to carry out the reaction by adding an aprotic polar solvent such as dimethyl sulfone or dimethyl sulfoxide in addition to alcohols such as methanol and ethanol.

When alcohols are used, the amount used is 2 to 20% by weight, more preferably 4 to 15% by weight, based on the amount of epihalohydrin. When an aprotic polar solvent is used, it is 5 to 1 relative to the amount of epihalohydrin.
The amount is 00% by weight, more preferably 10 to 90% by weight.

After washing these reaction products of the epoxidation reaction with or without washing with water, under heating and reduced pressure at 150 to 250 ° C.,
Excessive epihalohydrin and other added solvents are removed at a pressure of 10 mmHg or less. In order to make the epoxy resin less hydrolyzable halogen, the recovered epoxy resin is dissolved again in a solvent such as toluene or methyl isobutyl ketone, and an aqueous solution of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is added. In addition, it is possible to carry out a further reaction to ensure ring closure. In this case, the amount of the alkali metal hydroxide used is preferably 0.01 to 0.3 mol, and particularly preferably 0.05 to 0.1 mol, per 1 equivalent of the hydroxyl group of the polyphenol compound used for the epoxidation.
2 moles. The reaction temperature is 50 to 120 ° C., and the reaction time is usually 0.5 to 2 hours.

After the completion of the reaction, the formed salt is removed by filtration, washing with water and the like, and the solvent such as toluene and methyl isobutyl ketone is distilled off under heating and reduced pressure to obtain the epoxy resin of the present invention.

The epoxy resin composition of the present invention will be described below. The epoxy resin composition of the present invention can be obtained by using the epoxy resin of the present invention and / or the polyphenol compound of the present invention as an essential component, and further adding a curing accelerator and the like if necessary. (3),
In the epoxy resin composition described in (5) and (6), the polyphenol compound of the present invention can be used as the component (b) alone or in combination with other curing agents. When used together, the proportion of the polyphenol compound of the present invention in the total curing agent is preferably 30% by weight or more, and particularly preferably 40% by weight or more.

As the other curing agent used in combination with the polyphenol compound of the present invention, for example, amine compounds, acid anhydride compounds, amide compounds, phenol compounds and the like can be used. Specific examples include diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, dicyandiamide, a polyamide resin synthesized from a dimer of linolenic acid and ethylenediamine, phthalic anhydride, trimellitic anhydride, pyromyl anhydride. Mellitic acid, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic acid anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, phenol novolac, and modified products thereof, imidazo-
, BF ₃ -amine complex, guanidine derivative and the like, but are not limited thereto. These may be used alone or in combination of two or more.

In the epoxy resin composition described in (4), (5) and (6), the epoxy resin of the present invention can be used as the component (a) alone or in combination with other epoxy resins. When used in combination, the proportion of the epoxy resin of the present invention in the total epoxy resin is preferably 30% by weight or more, and particularly preferably 40% by weight or more.

Other epoxy resins used in combination with the epoxy resin of the present invention include novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, biphenyl type epoxy resins, etc. Or two or more may be used in combination.

In the epoxy resin composition described in (3) and (6), when the polyphenol compound of the present invention is used as a curing agent, the other epoxy resin described above or the epoxy resin of the present invention is used as the epoxy resin. You can

In the epoxy resin composition described in (4) and (6), when the epoxy resin of the present invention is used as the epoxy resin, the other curing agent described above or the polyphenol compound of the present invention is used as the curing agent. Can be used.

In the epoxy resin composition of the present invention, the amount of the curing agent (component (b)) used is preferably 0.7 to 1.2 equivalents relative to 1 equivalent of epoxy groups of the epoxy resin of component (a). If the amount is less than 0.7 equivalent or more than 1.2 equivalent to 1 equivalent of epoxy group, curing may be incomplete and good cured physical properties may not be obtained.

When the above curing agent is used, a curing accelerator may be used in combination. As the curing accelerator, for example, 2
-Methylimidazole, 2-ethylimidazole, 2-
Imidazoles such as ethyl 4-methyl-imidazole, 2
-(Dimethylaminomethyl) phenol, tertiary amines such as 1,8-diaza-bicyclo (5,4,0) undecene-7, phosphines such as triphenylphosphine,
Examples thereof include metal compounds such as tin octylate. The amount of the curing accelerator used is 0.
1 to 5.0 parts by weight is preferable. Furthermore, to the epoxy resin composition of the present invention, various compounding agents such as a filler such as silica, alumina and talc, a silane coupling agent, a release agent and a pigment can be added, if necessary.

The epoxy resin composition of the present invention can be obtained by uniformly mixing the above components. The epoxy resin composition of the present invention can be easily made into a cured product by a method similar to a conventionally known method. For example, the epoxy resin (component (a)) and the curing agent (component (b)), fillers and other additives are used, if necessary, until uniform using an extruder, a kneader, a roll or the like. The epoxy resin composition is sufficiently mixed to obtain an epoxy resin composition, and the epoxy resin composition is melted and then molded using a casting or transfer molding machine, and further heated at 80 to 200 ° C. for 2 to 10 hours to obtain a cured product. Can be obtained.

Further, the resin composition of the present invention is dissolved in a solvent such as toluene, xylene, acetone, methylethylketone, methylisobutylketone or the like to prepare a base such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber or paper. It is also possible to obtain a cured product by hot press-molding a prepreg obtained by impregnating a material with a material and heating and drying.

The amount of the diluent solvent used in this case is usually 10 to 70% by weight, preferably 15 to 65% by weight in the mixture of the epoxy resin composition of the present invention and the diluent solvent.

Since the cured product thus obtained is excellent in heat resistance, water resistance and mechanical strength, it can be used in a wide range of fields where heat resistance, water resistance and high mechanical strength are required.
Specifically, it is useful as any electric / electronic material such as a sealing material, a laminated plate, an insulating material, and the like. It can also be used in the fields of molding materials, adhesives, composite materials, paints and the like.

[0044]

EXAMPLES Next, the present invention will be described more specifically by way of Examples and Comparative Examples. In the following, parts are parts by weight unless otherwise specified.

Example 1 Phenol 940 was placed in a flask equipped with a thermometer, a dropping funnel, a cooling tube, a stirrer and a hydrogen chloride gas blowing tube.
Section, the following formula (4)

[0046]

[Chemical 6]

119 parts of the compound represented by and 3.0 parts of ethyl mercaptan were charged into a solution, and the solution was reacted at 40 ° C. for 20 hours while blowing hydrogen chloride gas. Then, a 20 wt% sodium dihydrogen phosphate aqueous solution 2.5
Parts, and after stirring, washing with water and removing excess phenol under heating and reduced pressure, the following formula (5)

[0048]

[Chemical 7]

269 parts of the compound (A) represented by the formula (polyphenol compound of the present invention) were obtained. The obtained polyphenol compound had a softening point of 116.2 ° C. and a hydroxyl group equivalent of 145 g / eq.

Example 2 Reaction was carried out in the same manner as in Example 1 except that m-cresol portion was used instead of phenol, and the following formula (6) was used.

[0050]

Embedded image

302 parts of the compound (B) represented by the formula (polyphenol compound of the present invention) were obtained. The softening point of the obtained polyphenol compound was 121.1 ° C., and the hydroxyl equivalent was 159 g / eq.

Examples 3 to 4 and Comparative Example 1 o-cresol novolac type epoxy resin (EOCN1020, manufactured by Nippon Kayaku Co., Ltd., softening point 65.1 ° C., epoxy equivalent 200 g / eq) as an epoxy resin and a curing agent. The obtained polyphenol compounds (A) to (B),
For comparison, phenol novolac resin (softening point 80.2
C., hydroxyl group equivalent: 106 g / eq), triphenylphosphine (TPP) was used as a curing accelerator, compounded in the composition shown in Table 1, and kneaded with a roll at 70 ° C. for 15 minutes to obtain 150.
Transfer molding at 180 ° C for 180 seconds at a molding pressure of 50 kg / cm ² , then at 160 ° C for 2 hours, then 180 ° C.
After curing for 8 hours, a test piece is prepared.
The water absorption rate and bending strength were measured. The results are shown in Table 1.
The conditions for measuring the glass transition point, water absorption and bending strength are as follows. Further, in the table, the numerical value in the column of composition of formulation shows parts by weight.

Glass transition temperature thermomechanical measuring device (TMA): TM-7000 manufactured by Vacuum Riko Co., Ltd. Temperature rising rate: 2 ° C./min Water absorption rate Test piece (cured product): Diameter 50 mm, thickness 3 mm Disk 100 ° C. in water Increase rate (%) after boiling in water for 24 hours Bending strength Value measured in accordance with JIS K-6911

[0054]

Table 1 Example 3 Example 4 Comparative Example 1 Composition of formulation EOCN1020 100 100 100 Compound (A) 72.5 Compound (B) 79.5 Phenol novolac resin 53.0 TPP 1 1 1 Physical properties of cured product Glass transition point (° C ) 185 188 153 Water absorption (%) 0.96 0.87 1.30 Bending strength 12.1 11.9 9.0

Example 5 The compound (A) obtained in Example 1 was subjected to a nitrogen gas purge in a flask equipped with a thermometer, a condenser and a stirrer.
145 parts, 370 parts of epichlorohydrin, and 92.5 parts of dimethyl sulfoxide were charged and dissolved. Flake-shaped sodium hydroxide (99% pure) heated to 50 ° C 4
0.4 parts were added in portions over 90 minutes, and then 60 ° C
For 2 hours and at 70 ° C. for 1 hour. After completion of reaction, 1
Dimethyl sulfoxide and epichlorohydrin were distilled off under heating and reduced pressure at 30 ° C., and 390 parts of methyl isobutyl ketone was added to the residue and dissolved.

Further, this methyl isobutyl ketone solution was heated to 70 ° C. to prepare a 30% by weight aqueous sodium hydroxide solution 1.
After adding 3.3 parts and reacting for 1 hour, washing with water was repeated 3 times to make the pH neutral. Further, the water layer is separated and removed, and methyl isobutyl ketone is distilled off from the oil layer under reduced pressure by heating using a rotary evaporator to obtain a compound represented by the following formula (7).

[0057]

[Chemical 9]

(G in the formula (7) represents a glycidyl group.)
188 parts of the epoxy resin (C) of the present invention represented by The obtained epoxy resin had a softening point of 85.2 ° C. and an epoxy equivalent of 216 g / eq.

Example 6 The reaction was carried out in the same manner as in Example 5 except that 159 parts of the compound (B) obtained in Example 2 was used in place of the compound (A), and the following formula (8) was used.

[0060]

[Chemical 10]

(In the formula (8), G represents a glycidyl group.)
204 parts of the epoxy resin (D) of the present invention represented by The obtained epoxy resin had a softening point of 93.2 ° C. and an epoxy equivalent of 233 g / eq.

Examples 7 to 8 and Comparative Example 2 Epoxy resins (C) to (D) obtained above, and as a comparison, o-cresol novolac type epoxy resin (EOCN)
1020, manufactured by Nippon Kayaku Co., Ltd., softening point 65.1 ° C., epoxy equivalent 200 g / eq, phenol novolac resin as a curing agent (hydroxyl group equivalent 106 g / eq, softening point 8)
0.2 ° C.), triphenylphosphine (TPP) was used as a curing accelerator, and compounded in the composition shown in Table 2 to 70 ° C.
Kneading with a roll for 15 minutes at 150 ℃, molding pressure 50kg
/ Cm ² in to 180 seconds transfer molding, 2 hours then 160 ° C., further create a 8 hours curing allowed test piece at 180 ° C., was measured glass transition point, the water absorption and mechanical strength. Table 2 shows the results. The conditions for measuring the glass transition point, the water absorption rate and the bending strength are as described above. Also,
In the table, the numerical value in the column of composition of formulation shows parts by weight.

[0063]

Table 2 Table 7 Example 7 Example 8 Comparative Example 2 Composition of Formulation Epoxy Resin (C) 100 Epoxy Resin (D) 100 EOCN1020 100 (Epoxy Equivalent (g / eq)) 216 233 200 Phenol Novolac Resin 49.1 45.5 53.0 TPP 1 1 1 1 Physical properties of cured product Glass transition point (℃) 190 192 153 Water absorption rate (%) 0.92 0.88 1.30 Bending strength (Kg / mm ² ) 12.6 13.1 9.0

Example 9, Comparative Example 3 The epoxy resin (C) obtained in Example 5, the polyphenol compound (A) obtained in Example 1, o-
Cresol novolac type epoxy resin (EOCN102
0, manufactured by Nippon Kayaku Co., Ltd., softening point 65.1 ° C., epoxy equivalent 200 g / eq, and a phenol novolac resin (hydroxyl group equivalent 106 g / eq, softening point 80.
2 ° C.), triphenylphosphine (T
PP) and compounded in the composition shown in Table 3 to 1 at 70 ° C.
Kneading with a roll for 5 minutes, 150 ℃, molding pressure 50kg / c
Transfer molding at m ² for 180 seconds, then 16
A test piece was prepared by curing at 0 ° C. for 2 hours and further at 180 ° C. for 8 hours, and the glass transition point, water absorption and mechanical strength were measured. The results are shown in Table 3. The conditions for measuring the glass transition point, the water absorption rate and the bending strength are as described above. Further, in the table, the numerical value in the column of composition of formulation shows parts by weight.

[0065]

Table 3 Table 3 Example 9 Comparative Example 3 Composition of Formulation Epoxy Resin (C) 100 EOCN1020 100 (Epoxy Equivalent (g / eq)) 216 200 Polyphenol Compound (A) 67.1 Phenol Novolac Resin 53.0 TPP 1 1 Curing Physical properties of material Glass transition point (℃) 196 153 Water absorption rate (%) 0.89 1.30 Bending strength (Kg / mm ² ) 13.5 9.0

As described above, from Tables 1 to 3, the cured product of the epoxy resin composition using the polyphenols and / or the epoxy resin of the present invention has a higher glass transition point and lower water absorption than the cured product of the known resin composition. And showed high mechanical strength.

[0067]

The epoxy resin composition using the polyphenols and / or the epoxy resin of the present invention has heat resistance, water resistance and mechanical strength as compared with the epoxy resin compositions generally used conventionally. Gives an excellent cured product. Therefore, the epoxy resin composition of the present invention can provide a cured product having excellent properties such as heat resistance, water resistance and mechanical strength, and can be used as a molding material, a casting material, a laminating material, a paint, an adhesive, a resist. It is extremely useful for a wide range of applications such as.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C08G 59/62 NJF C09K 3/10 Z

Claims (7)

[Claims] 1. A formula (1): (In the formula (1), P and R each represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group, and each P and R may be the same or different from each other. In addition, Q represents a polyphenol compound represented by an alkyl group having 1 to 3 carbon atoms. 2. Formula (2): (In formula (2), P, R, and Q have the same meanings as in formula (1), and G represents a glycidyl group). 3. An epoxy resin composition comprising (a) an epoxy resin (b) a polyphenol compound of formula (1) according to claim 1. 4. An epoxy resin composition comprising (a) an epoxy resin of the formula (2) according to claim 2 and (b) a curing agent. 5. An epoxy resin composition comprising (a) an epoxy resin of the formula (2) according to claim 2 and (b) a polyphenol compound of the formula (1) according to claim 1. 6. The epoxy resin composition according to claim 3, 4 or 5 containing a curing accelerator. 7. A cured product obtained by curing the epoxy resin composition according to claim 3, 4, 5 or 6.