TWI520980B - The epoxy resin composition and cured - Google Patents

Description

Epoxy resin composition and hardened material

The present invention relates to an epoxy resin composition having low viscosity and excellent workability, and an epoxy resin cured product which is excellent in heat resistance and mechanical properties obtained by curing.

The epoxy resin is cured by various curing agents to obtain a cured product excellent in general mechanical properties, water resistance, chemical resistance, heat resistance, electrical properties, etc., and can be used for an adhesive, a coating, a laminate, and a molding. A wide range of materials, mold materials, etc. Conventionally, in the liquid epoxy resin composition, a bisphenol A type epoxy resin or a bisphenol F type epoxy resin is mainly used for the epoxy resin, but the viscosity of the resin is relatively high, and a reactive diluent is often added. Representative examples of the reactive diluent are butyl glycidyl ether, allyl glycidyl ether, and phenyl glycidyl ether.

When a diluent such as a conventional butyl glycidyl ether, allyl glycidyl ether or phenyl glycidyl ether is added, when the amount is too large, there is a problem that the heat resistance or mechanical strength of the cured product is lowered. Therefore, as described in Patent Documents 1 and 2, a reactive diluent having a bifunctional or higher epoxy group has been proposed. However, the reaction diluent described in Patent Document 1 has a low viscosity but is an alicyclic epoxy group. Therefore, if it is less reactive than the conventional epichlorohydrin type epoxy compound, it can only be known as an acid anhydride hardening system, and its use is limited. Further, in Patent Document 2, a compound containing a cyclohexyl group has been proposed. However, the viscosity of the compound is 240 cps to 3200 cps, and the viscosity is high as compared with the conventional reactive diluent, and the function as a diluent is insufficient.

In order to solve such problems, the inventors first discovered the use of polyepoxy benzenes as reactive diluents. These are those which reduce the viscosity of the entire composition, have reactivity equivalent to an epichlorohydrin type epoxy group, and are reactive diluents which do not deteriorate the heat resistance and mechanical properties of the cured product. However, since it is an aromatic compound, it has a problem that transparency and light resistance are slightly inferior to those of an alicyclic compound.

[Previous Technical Literature]

[Patent Document 1] Japanese Patent Publication No. 7-97431

[Patent Document 2] Patent No. 3415047

[Disclosure of the Invention]

Therefore, in the case of the reactive diluent, it is desired to reduce the viscosity of the entire composition, have reactivity equivalent to that of the epichlorohydrin type epoxy group, and do not deteriorate the heat resistance and mechanical properties of the cured product. Thinner. Further, in electrical and electronic parts applications, an epoxy resin having a low chlorine concentration is desired, and a reactive diluent having a low chlorine content is expected to occur. Further, in the field of optical parts, transparency and light resistance are also sought.

The inventors of the present invention have found that a reactive diluent having a very low viscosity and a low chlorine content without lowering the heat resistance and mechanical properties of the cured product has been intensively studied. 1) The epoxy compound shown satisfies the requirements of these and the present invention is completed.

That is, the present invention relates to an epoxy resin composition comprising an epoxy resin having a viscosity of not more than 1000 mPa ‧ at 25 ° C and a polyepoxyethylcyclohexane represented by the following formula (1) The content of the polyepoxyethylcyclohexane is 1 part by weight or more and 90 parts by weight or less based on 100 parts by weight of the epoxy resin;

【化1】

(wherein E represents an epoxy group, R represents hydrogen, a vinyl group or an alkyl group, and n represents an integer of 2 to 3).

The present invention relates to an epoxy resin cured product characterized in that a hardener is blended in the above epoxy resin composition to harden it.

The present invention relates to an epoxy resin composition characterized in that the above polyepoxyethylcyclohexane is 1,2,4-trisethoxyethylcyclohexane.

The present invention relates to a reactive diluent for an epoxy resin characterized by the above polyepoxyethylcyclohexane.

[Best form for implementing the invention]

Hereinafter, the present invention will be described in detail.

The epoxy resin composition of the present invention contains an epoxy resin having a viscosity of not less than 1000 mPa·s at 25 ° C and a polyepoxyethylcyclohexane represented by the above formula (1) (hereinafter, Known as epoxy compound).

The epoxy compound represented by the formula (1) can be used by epoxidizing a corresponding vinyl compound by peroxide. When a part of R is a vinyl epoxy compound, when the polyvinylcyclohexane is epoxidized, a part of the ethylene is not epoxidized, and a part of the epoxy is not reacted. The epoxy compound obtained by this method does not use epichlorohydrin when it is synthesized, and therefore has a characteristic that the chlorine content is small. As the peroxide used in the epoxidation, a general peroxygen or organic peroxide can be used.

As described above, the epoxy compound can be advantageously obtained by epoxidation of oxidation of polyvinylcyclohexanes (hereinafter also referred to as vinyl compounds). In this case, when the polyvinylcyclohexane is a mixture of stereoisomers, the epoxy compound also becomes a mixture of stereoisomers, but it is no problem.

The polyepoxyethylcyclohexane represented by the formula (1) has n, that is, 2 or 3 epoxy groups, but when it is intended for high heat resistance and high strength, it is used for crosslinking at the time of hardening. Density, it is preferably trisethoxycyclohexane. Further, it may be a mixture of n=2 and n=3. In the formula (1), R is hydrogen, a vinyl group or an alkyl group, and the alkyl group is an alkyl group having 1 to 6 carbon atoms, and the viscosity is low, and the effect as a diluent is particularly high. Further, 6-n of the R systems may be the same or different. In order to lower the viscosity, all of R is hydrogen, or 1 to 3 of R are hydrogen, and the remainder is a vinyl group or an alkyl group, and the total number of carbon atoms derived from a vinyl group or an alkyl group is preferably 4 or less.

The epoxy resin used in the epoxy resin composition of the present invention having a viscosity at 25 ° C of not more than 1000 mPa ‧ s is not particularly limited as long as it satisfies the above viscosity. For example, bisphenol A type, bisphenol F type, bisphenol AD type, bromine-containing bisphenol A type, phenol novolak type, cresol novolak type, polyphenol type, linear aliphatic type, butadiene a glycidyl ether type epoxy resin such as a urethane type; a glycidyl hexahydrophthalate, a glycidyl acid ester, an aromatic system, a cyclic aliphatic system, or an aliphatic system Glyceryl ester type epoxy resin; bisphenol type, ester type, high molecular weight ether ester type, ether ester type, bromine type, novolak type, methyl substituted type epoxy resin; heterocyclic epoxy resin; triglycidyl a glycidylamine type epoxy resin such as a trimeric isocyanate or a tetraglycidyldiaminodiphenylmethane; a linear aliphatic epoxy resin such as an epoxidized polybutadiene or an epoxy soybean oil; An epoxy resin such as an aliphatic epoxy resin, a naphthalene novolac type epoxy resin or a diglycidyl phthalocyanine epoxy resin has a viscosity at 25 ° C of 1000 mPa ‧ s or more, but performance and Economically, it is especially suitable for bisphenol A type, bisphenol F type, bisphenol AD type, cresol novolak type Ether type epoxy resin of 2 or more functional epoxy resin. Specific examples of such an epoxy resin include EPICLON 850 (epoxy equivalent weight: 188 g/eq) manufactured by Dainippon Ink Chemical Industry Co., Ltd., and Epiclon 1050 (epoxy equivalent weight: 475 g/eq). Alcohol condensate epoxy resin, bisphenol F-epichlorohydrin condensate epoxy resin such as EPICLON 830 (epoxy equivalent weight 172 g/eq), EPICLON N-740 (epoxy equivalent weight 180 g/eq), EPICLON N- a tetrabromobisphenol A-epichlorohydrin condensate ring of phenolic varnish resin such as 670 (epoxy equivalent 210 g/eq), epichlorohydrin condensate epoxy resin, EPICLON 152 (epoxy equivalent 360 g/eq) An aromatic glycidyl ether type epoxy resin such as an oxygen resin or an ethylene carbonate-based epoxy resin such as EPICLON 430 (epoxy equivalent weight: 120 g/eq). The epoxy resin having a viscosity of less than 1000 mPa·s at 25 ° C has a low viscosity reduction effect of the epoxy compound of the formula (1).

The epoxy compound represented by the formula (1) which can be used in the epoxy resin composition of the present invention has a function of lowering the viscosity of the epoxy resin composition. In particular, if the viscosity of the epoxy compound is in the range of 10 to 500 mPa ‧ s, the function of lowering the viscosity is excellent. Further, since the epoxy resin having a viscosity of not less than 1000 mPa ‧ at 25 ° C is a general epoxy resin, it has the unique properties of the epoxy resin, but has a high viscosity. Hereinafter, an epoxy resin having a viscosity at 25 ° C of 1000 mPa ‧ or more is also referred to as a high-viscosity epoxy resin.

The amount of the epoxy compound to be added in the formula (1) is required to be in the range of 1 to 90 parts by weight based on 100 parts by weight of the high-viscosity epoxy resin. It is preferably 5 to 80 parts by weight, more preferably 10 to 60 parts by weight. When the amount is less than 1 part by weight, the effect of lowering the viscosity is insufficient, and if it exceeds 90 parts by weight, the physical properties of the original epoxy resin are lowered.

The epoxy compound represented by the formula (1) is excellent as an epoxy resin diluent. The conventional epoxy resin diluent sufficiently reduces the Tg or strength of the cured product obtained by curing the epoxy resin composition, but the epoxy compound represented by the formula (1) used in the present invention is low in viscosity and The dilution effect is high, but if it is hardened, it becomes high Tg and high strength. Moreover, since this epoxy compound has an alicyclic structure, it has an effect of high transparency.

Further, the epoxy resin composition may further contain a flexible agent, a coupling agent, a flame retardant, a flame resistant auxiliary, a coloring agent which are generally blended in the field of use thereof, as long as the performance of the present invention is not impaired. Additives such as fillers.

A hardener is added to the epoxy resin composition of the present invention to be hardened to obtain an epoxy resin cured product.

The hardener to be used in the epoxy resin composition of the present invention may be a known hardener for a hardener of a general epoxy resin, and examples thereof include ethylenediamine, diethylenetriamine, and trisium. The first of ethylenetetramine, tetraethylenepentamine, dipropylenetriamine, diethylaminopropylamine, m-phenylenediamine, p,p'-diaminodiphenylmethane, diaminodiphenylanthracene, etc. Amines; second amines such as diethanolamine, N-methylethanolamine, bishydroxyethyldiethylenetriamine; triethylamine, hexahydropyridine, benzyldimethylamine 2-(dimethylamino a third amine such as methyl)phenol; an anhydride such as phthalic anhydride, hexahydrophthalic anhydride, dodecenyl succinic anhydride, pyromellitic anhydride, trimellitic anhydride, chlorendic anhydride; One or more of these are blended.

The blending ratio of the epoxy resin to the hardener is preferably in the range of from 0.8 to 1.5 in terms of the equivalent ratio of the epoxy group to the functional group in the hardener. Outside of this range, the epoxy group which is not reacted after hardening or the functional group in the hardener remains, and the physical properties of the cured product are lowered. Here, the epoxy compound represented by the formula (1) is calculated by forming an epoxy resin.

The use of the epoxy resin composition of the present invention may be, for example, a composite material such as a paint, an injection material, a mold product, or a CFRP, a laminate or a laminate of a molded article or a printed substrate, or a sealing material for an electric or electronic component. Adhesives, laminates, optical materials, FRP molded articles, repair materials for civil engineering, flooring materials, road paving materials, and the like.

[Examples]

Next, in order to make the features of the present invention more specific, the embodiments will be specifically described. Also, all parts and % of the text indicate the weight basis.

Synthesis Example 1

80 g (0.49 mol) of 1,2,4-trivinylcyclohexane, 323 g (7.87 mol) of acetonitrile, 560 g (17.5 mol) of methanol, and 175 g (1.27 mol) of potassium carbonate were placed in a thermometer, a cooling tube, and nitrogen. Introduce a tube and stir the leaves in a 2-liter five-necked flask. After the substitution with nitrogen, the internal temperature was adjusted to 20 to 25 ° C, and 630 g (5.55 mol) of 30% hydrogen peroxide water was added dropwise over 2 hours. After the completion of the dropwise addition, the reaction was carried out for 5 hours while maintaining the internal temperature at 25 to 45 °C. After the completion of the reaction, 186.6 g (0.15 mol) of a 10% aqueous sodium sulfite solution was allowed to decompose the residual peroxide in the reaction liquid. 600 g (6.51 mol) of toluene was added to separate the aqueous layer from the organic layer. After separation, the organic layer was washed three times with water and dried over sodium sulfate. After the organic layer (toluene layer) was distilled off using an evaporator, the epoxy mixture (containing a monoepoxy group, a diepoxy group, or a tricyclooxy group) was distilled off under reduced pressure to purify and separate. 8.74 g (0.049 mol, yield 10%) of monoepoxy group, 27.22 g (0.140 mol, 29%) of dicyclopentoxide, and 1,2,4-trisethoxyethylcyclohexane (TEpCH) were obtained. 29.87 g (0.142 mol, yield 29%). The 1,2,4-trisethoxyethylcyclohexane (TEpCH) had an epoxy equivalent weight of 93 g/eq and a viscosity of 115 mPa ‧ s.

Synthesis Example 2

Into a 3-liter reactor, 300 g of divinylbenzene (97-% of DVB-960 divinylbenzene, m-body/p-body = 62:38) and 1200 g of ethyl acetate were charged and stirred. . Then, 1640 g of an ethyl acetate solution containing 30% of peracetic acid was added dropwise for 3 hours. Control was carried out during the dropwise addition so that the reaction temperature became 30 °C. After the dropwise addition, the mixture was further stirred at 30 ° C for 3 hours. After cooling the reaction mixture to room temperature, 1208 g of a 20% aqueous NaOH solution was added, and after stirring for 1 hour, the aqueous layer was separated to remove unreacted peracetic acid and the resulting acetic acid. Ethyl acetate was distilled off under reduced pressure using an evaporator, and then subjected to purification distillation (distillation temperature: 10 torr, 150 ° C) to obtain 151.6 g of diethoxyethylbenzene (DEpEB). The epoxy equivalent of the obtained di-epoxyethylbenzene was 81 g/eq, the viscosity at 25 ° C was 18 mPa ‧ , the purity was 97.1% (% of gas chromatographic analysis area), m-body/p-body =64:36 (1H-NMR integration ratio).

Example 1~3

The 1,2,4-trisethoxyethylcyclohexane (TEpCH) 10 obtained in Synthesis Example 1 was added to 100 parts by weight of bisphenol A type epoxy resin (YD-128; manufactured by Tosho Kasei Co., Ltd.). The parts by weight, 25 parts by weight or 50 parts by weight are mixed to obtain an epoxy resin composition. The viscosity of the resin composition at 25 ° C was measured by a B type viscometer. Rikacid MH-700 (manufactured by Shin-Nippon Chemical Co., Ltd.) was added to the epoxy resin composition so that the equivalent ratio became 0.9 and uniformly mixed, and then flowed into the mold to heat-harden at 120 ° C for 1 hour, then 150 ° C for 3 hours. A test piece for bending test of 125 mm in length × 13 mm in width × 9 mm in thickness, and a test piece for measuring glass transition point of 5 mm in diameter × 3 mm in thickness were produced.

The bending test specified in JIS K 7171 was carried out at 25 ° C using the test piece for bending test produced, and the bending strength was determined from the maximum strength. Further, the bending elastic modulus was obtained from the initial slope of the deformation-stress curve. Further, using the produced test piece for measuring glass transition point, a glass mechanical transfer was obtained by a thermomechanical analyzer (TMA/SS) manufactured by SII. Nanotechnology Co., Ltd. under a nitrogen atmosphere at a temperature increase rate of 7 ° C /min. Point (Tg). The results are shown in Table 1.

Comparative example 1~3

10 parts by weight, 25 parts by weight, or 50 parts by weight of phenyl glycidyl ether (PGE; manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 100 parts by weight of bisphenol A type epoxy resin (YD-128), and mixed. Epoxy resin composition. After adding Rikacid MH-700 to the epoxy resin composition so that the equivalent ratio became 0.9 and uniformly mixed, a test piece for bending test and a test piece for measuring glass transition point were prepared in the same manner as in Examples 1 to 3. Bending strength, flexural modulus and glass transition point.

Comparative Example 4~6

10 parts by weight, 25 parts by weight, or 50 parts by weight of butyl glycidyl ether (BGE; manufactured by Tokyo Chemical Industry Co., Ltd.) was added to 100 parts by weight of the bisphenol A type epoxy resin (YD-128), and the mixture was mixed. Epoxy resin composition. After adding Rikacid MH-700 to the epoxy resin composition so that the equivalent ratio became 0.9 and uniformly mixed, a test piece for bending test and a test piece for measuring glass transition point were prepared in the same manner as in Examples 1 to 3. Bending strength, flexural modulus and glass transition point.

Example 4

The 1,2,4-trisethoxyethylcyclohexane (TEpCH) 50 obtained in Synthesis Example 1 was added to 100 parts by weight of bisphenol F-type epoxy resin (YD-170; manufactured by Tosho Kasei Co., Ltd.). The parts by weight were mixed to obtain an epoxy resin composition. The viscosity of the resin composition at 25 ° C was measured by a B type viscometer. After adding Rikacid MH-700 to the epoxy resin composition so that the equivalent ratio became 0.9 and uniformly mixed, a test piece for bending test and a test piece for measuring glass transition point were prepared in the same manner as in Examples 1 to 3. Bending strength, flexural modulus and glass transition point.

Example 5

The 1,2,4-trisethoxyethylcyclohexane (TEpCH) 50 obtained in Synthesis Example 1 was added to 100 parts by weight of a phenol novolac type epoxy resin (YDPN-638; manufactured by Tohto Kasei Co., Ltd.). The parts by weight were mixed to obtain an epoxy resin composition. After adding Rikacid MH-700 to the epoxy resin composition so that the equivalent ratio became 0.9 and uniformly mixed, a test piece for bending test and a test piece for measuring glass transition point were prepared in the same manner as in Examples 1 to 3. Bending strength, flexural modulus and glass transition point.

The blending composition and the viscosity of the resin compositions of Examples 1 to 5 and Comparative Examples 1 to 6 and the measured values of the physical properties of the cured product are shown in Table 1. Further, the amount of the compound added is the amount of the epoxy compound blended with respect to 100 parts by weight of the epoxy resin. The viscosity was measured at 25 °C. Further, the viscosity is the viscosity of the epoxy resin composition before the hardener is blended.

Comparative Example 7

After adding Rikacid MH-700 to the bisphenol A type epoxy resin (YD-128) so that the equivalent ratio became 0.9 and uniformly mixed, a test piece for bending test and glass transfer were produced in the same manner as in Examples 1 to 3. The test piece for measurement was used, and the bending strength, the bending elastic modulus, and the glass transition point were determined.

Comparative Example 8

After adding Rikacid MH-700 to the bisphenol F-type epoxy resin (YD-170) so that the equivalent ratio became 0.9 and uniformly mixed, a test piece for bending test and glass transfer were produced in the same manner as in Examples 1 to 3. The test piece for measurement was used, and the bending strength, the bending elastic modulus, and the glass transition point were determined.

Comparative Example 9

After adding Rikacid MH-700 to the phenol novolak type epoxy resin (YDPN-638) so that the equivalent ratio became 0.9 and uniformly mixed, a test piece for bending test and glass transfer were produced in the same manner as in Examples 1 to 3. The test piece for measurement was used, and the bending strength, the bending elastic modulus, and the glass transition point were determined.

The measured values of the viscosity at 25 ° C and the physical properties of the cured product of the epoxy resins used in Comparative Examples 7 to 9 are shown in Table 2. Further, the amount of the compound added was 0.

Reference example

After measuring the hydrolyzable chlorine concentration of phenyl glycidyl ether (PGE), butyl glycidyl ether (BGE) and TEpCH, the following is as follows.

TEpCH: not detected

PGE: 53ppm

BGE: 16ppm

The hydrolyzable chlorine content was analyzed by the following method. That is, about 1 g of the sample was accurately taken into a 100 ml Erlenmeyer flask and accurately weighed to a unit of 1 mg. 30 ml of dioxane was added and completely dissolved using an ultrasonic cleaner. After 5 ml of a 1 N potassium hydroxide ‧ ethanol solution was correctly added, the mixture was sufficiently shaken and mixed, and then zeolite was added to install a cooling tube. Heat to about 180 ° C and reflux. The reflux time was 30 minutes after the start of boiling. After cooling to room temperature, the cooling tube was washed with 5 ml of methanol, and the washing liquid was added to the sample liquid. The flask was removed from the cooling tube and the sample was transferred to a 200 ml beaker. The mixture was washed three times in 50 ml of 80% acetone water, and the washing liquid was added to the sample liquid. 5 ml of N/400 sodium chloride solution was added correctly, and the rotor was placed. After adding 3 ml of acetic acid and stirring for 2 minutes, potentiometric titration was carried out using N/100 silver nitrate solution under the following conditions. Perform the empty test in the same operation as above.

The hydrolyzable chlorine concentration was determined according to the following formula.

Hydrolyzable chlorine (%) = F × (V - B) × 0.0355 / S

F: factor of N/100 silver nitrate solution

V: The amount of N/100 silver nitrate solution required for the titration of the sample

B: The amount of N/100 silver nitrate solution required for the titration of the empty test

S: sample amount (g)

Example 6

The 1,2,4-three obtained in Synthesis Example 1 was added to 100 parts by weight of a hydrogenated bisphenol A glycidyl ether type epoxy resin (Rikresin HBE-100; viscosity (1950 cps 25 ° C) manufactured by Nippon Chemical and Chemical Co., Ltd.). Epoxyethylcyclohexane (TEpCH) 50 parts by weight, mixed to obtain an epoxy resin composition. In this epoxy resin composition, Rikacid MH-700 was added to uniformly mix the equivalent ratio to 0.9, and then vacuum After degassing, it was cured in a mold at 100 ° C for 4 hours and further at 140 ° C for 12 hours to prepare a resin plate having a thickness of 1 mm and 4 mm. The test piece was used to measure the initial transmittance and UV resistance of the cured product. In the same manner as in the first to third embodiments, a test piece for bending test and a test piece for measuring glass transition point were produced, and bending strength, bending elastic modulus, and glass transition point were determined.

Comparative Example 10

The dicyclohexylethylbenzene obtained in Synthesis Example 2 was added to 100 parts by weight of a hydrogenated bisphenol A glycidyl ether type epoxy resin (Rikresin HBE-100; viscosity (1950 cps 25 ° C) manufactured by Nippon Chemical and Chemical Co., Ltd.). (DEpEB) 50 parts by weight, mixed to obtain an epoxy resin composition. In this epoxy resin composition, Rikacid MH-700 was added to uniformly mix the equivalent ratio to 0.9, and then vacuum degassed in a mold to After curing at 100 ° C for 4 hours and further curing at 140 ° C for 12 hours, a resin plate having a thickness of 1 mm and 4 mm was produced. Using this test piece, the initial transmittance of the cured product, the measurement of the UV resistance, and the initial heat resistance were measured. In the same manner as in the examples 1 to 3, a test piece for bending test and a test piece for measuring glass transition point were produced, and the bending strength, the bending elastic modulus, and the glass transition point were determined.

In Example 6 and Comparative Example 10, the initial transparency, the UV resistance, and the initial heat resistance of the cured product were measured by the following methods.

Initial transparency

The transmittance of the cured product of 400 nm was measured using a self-recording spectrophotometer U-3410 manufactured by Hitachi, Ltd. on a resin plate having a thickness of 1 mm.

UV resistance

The resin plate having a thickness of 4 mm was measured in the same manner as the initial transmittance by using a weather resistance tester QUV manufactured by Q Panel Co., Ltd. and having a transmittance of 400 nm after UV irradiation for 600 hours. The lamp system used in the QUV uses UVA 340 nm and the black panel temperature is 55 °C.

Initial heat resistance

The transmittance of 400 nm after exposure to a resin plate having a thickness of 1 mm in an environment of 150 ° C for 72 hours was measured in the same manner as the initial transmittance.

The blending composition, the viscosity, the physical property value of the cured product, the initial transparency of the cured product, the UV resistance, and the initial heat resistance of the resin compositions of Example 6 and Comparative Example 10 are shown in Table 3. Further, the amount of the compound added was based on the amount of the epoxy compound blended with 100 parts by weight of the epoxy resin.

As shown in Table 3, the cured product of TEpCH was excellent in initial transmittance, UV resistance, and initial heat resistance. That is, it is excellent in transparency and light resistance, and can be used as an optical resin.

[Industry use possibility]

The epoxy resin composition of the present invention is low in viscosity and excellent in workability, and the cured epoxy resin obtained by curing is excellent in heat resistance, mechanical properties, transparency, and light resistance.

Claims (4)

An epoxy resin composition characterized by comprising an epoxy resin having a viscosity of not more than 1000 mPa·s at 25 ° C and a polyepoxyethyl ring represented by the following formula (1) having a viscosity of 10 to 500 Pa·s The content of hexane or polyepoxyethylcyclohexane is 10 parts by weight or more and 60 parts by weight or less based on 100 parts by weight of the epoxy resin; In the formula, E represents an epoxy group, R represents hydrogen, a vinyl group or an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 2 to 3. The epoxy resin composition of claim 1, wherein the polyepoxyethylcyclohexane is 1,2,4-trisethoxyethylcyclohexane. An epoxy resin cured product characterized by being blended in an epoxy resin composition as in the first aspect of the patent application, in an amount equivalent to a functional group equivalent ratio of an epoxy group to a hardener of 0.8 to 1.5. A hardener of the first amine, the second amine, the third amine, and the acid anhydride is hardened. A reactive diluent for epoxy resin, which is characterized by a polyepoxyethylcyclohexane represented by the following formula (1) having a viscosity of 10 to 500 Pa s at 25 ° C. In the formula, E represents an epoxy group, R represents hydrogen, a vinyl group or an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 2 to 3.