JP2023049343A - Epoxy resin composition and fiber-reinforced plastic - Google Patents

Abstract

To provide an in-situ polymerization type epoxy resin composition which has excellent heat resistance and impact resistance and causes less gel formation.SOLUTION: There is provided an epoxy resin composition which comprises a bifunctional epoxy resin, a bifunctional acetyl compound and a polymerization catalyst and becomes thermoplastic through a polymerization reaction, wherein 50 wt.% or more of the bifunctional epoxy resin is an epoxy resin (a) represented by the following formula (1), the amount of the bifunctional epoxy resin is 0.95 to 1.05 moles based on 1 mole of the bifunctional acetyl compound, the bifunctional acetyl compound is uniformly dissolved in the bifunctional epoxy resin and a polymer of the epoxy resin composition has a weight average molecular weight of 35,000 or more and to 200,000 or less and an impact strength of 48 kJ/m2 or more. (Here, A is a bivalent group and n is an average value of 0 to 5.)SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to epoxy resin compositions, reinforcing fiber-containing epoxy resin compositions, prepregs, and fiber-reinforced plastics and thermoplastics using these.

Fiber reinforced plastic (FRP) exhibits excellent physical properties such as light weight and high strength, and is used in many fields. Among them, those using carbon fiber as a reinforcing fiber (CFRP) are known to be particularly excellent in mechanical strength.

Epoxy resins are mainly used as base material resins for FRP because of their excellent balance between price and physical properties. , a method of polymerizing by polyaddition reaction using a polymerization catalyst and a reaction retardant to form a fiber-reinforced thermoplastic resin. Patent Document 2 discloses a polyaddition reaction between a bifunctional epoxy compound and a bifunctional compound having a functional group selected from the group consisting of a phenolic hydroxyl group, an amino group, a carboxyl group, a mercapto group, an isocyanate group and a cyanate ester group. is also proposed. Such epoxy resins are also called on-site polymerization type thermoplastic epoxy resins, and FRPs using them are expected to be excellent in mass productivity, moldability, and recyclability. In-situ polymerizable thermoplastic epoxy resins have good impregnation properties because they are impregnated into fibers in a low viscosity state before polymerization. Excellent for

One of the required properties of FRP is an improvement in heat resistance. Heat resistance of 120° C. or more is useful because it expands the range of applicable members. Techniques for improving the heat resistance of epoxy resins include increasing the crosslink density and applying a skeleton with a rigid molecular structure. The increase in crosslink density is unsuitable for in-situ thermoplastic epoxy resins, which are thermoplastic resins. A change to a rigid skeleton results in an increase in resin viscosity and deterioration in compatibility of reaction components. As a result, the process of impregnating the fibers with the resin becomes difficult, and the reactivity within the fibers also decreases.

Patent Documents 3 to 5 propose acylation of secondary hydroxyl groups present in epoxy resins, but do not discuss in-situ polymerization type thermoplastic epoxy resins.

JP 2006-321897 A WO2004/060981 JP-A-8-333437 JP-A-10-168287 JP 2016-89165 A

According to the studies of the present inventors, when a phenolic compound with a rigid skeleton is used as a technique for increasing the heat resistance of a thermoplastic epoxy resin, the melting point of the phenolic compound is high and the solubility is poor. It is difficult to dissolve uniformly. If the reaction components are not uniformly dissolved in the epoxy resin and precipitated, the polymerization reaction of the in-situ polymerizable epoxy resin cannot proceed sufficiently in the fiber. If a solvent is used, it is possible to dissolve the phenolic compound with a rigid skeleton in the epoxy resin, but the solvent component inhibits the polymerization reaction, and if it remains in the molded product, it leads to deterioration of physical properties, which is not preferable. .

With the aim of imparting heat resistance without impairing the reactivity of thermoplastic epoxy resins, the present inventors conducted intensive studies and found that acetylation lowers the melting point of phenolic compounds. We found that by using an acetyl compound, it is possible to uniformly dissolve a compound having a rigid skeleton in an epoxy resin without using a solvent, and that the polymerization reaction can proceed sufficiently even in the fiber.

ここで、Ａは式（２）で表される２価の基であり、ｎは繰り返し数であり、その平均値は０～５である。Ｘは単結合、炭素数１～１３の炭化水素基、－Ｏ－、－ＣＯ－、－ＣＯＯ－、－Ｓ－、又は－ＳＯ_２－であり、Ｙ^１は独立に、炭素数１～４のアルキル基、又は炭素数６～１０のアリール基であり、Ｙ^２及びＹ^３はそれぞれ独立に、水素原子、炭素数１～４のアルキル基、又は炭素数６～１０のアリール基である。 That is, the present invention provides an epoxy resin composition that contains a difunctional epoxy resin, a difunctional acetyl compound, and a polymerization catalyst as essential components and becomes a thermoplastic by a polymerization reaction, wherein 50% by weight or more of the bifunctional epoxy resin is It is an epoxy resin (a) represented by the following formula (1), with respect to 1 mol of a bifunctional acetyl compound, the bifunctional epoxy resin is 0.95 to 1.05 mol, and the bifunctional acetyl compound is a bifunctional It is uniformly dissolved in the epoxy resin, and the polymer obtained by polymerizing the epoxy resin composition has a weight-average molecular weight of 35,000 or more and 200,000 or less, and an impact strength measured by an unnotched Izod impact test of 48 kJ/ The epoxy resin composition is characterized by having a ^m2 or more.

Here, A is a divalent group represented by formula (2), n is the number of repetitions, and its average value is 0-5. X is a single bond, a hydrocarbon group having 1 to 13 carbon atoms, —O—, —CO—, —COO—, —S—, or —SO ₂ —, and Y ¹ independently represents 1 to 4 carbon atoms; or an aryl group having 6 to 10 carbon atoms, and Y ² and Y ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

The epoxy resin composition further contains a bifunctional phenol compound, the molar ratio of the bifunctional acetyl compound and the bifunctional phenol compound is 1/99 to 99/1, and the total amount of the bifunctional acetyl compound and the bifunctional phenol compound is 1 mol. On the other hand, the bifunctional epoxy resin is 0.95 to 1.05 mol, and the bifunctional acetyl compound and the bifunctional phenol compound may be uniformly dissolved in the epoxy resin, and the bifunctional phenol compound content The amount is preferably 5% or more and 40% or less by weight of the epoxy resin composition.

The epoxy resin composition preferably contains no organic solvent, or when it contains an organic solvent, the content of the organic solvent is preferably 0.05% by weight or more and 10% by weight or less of the epoxy resin composition.

The glass transition temperature of the polymer is preferably 120° C. or higher.

The present invention also provides a reinforcing fiber-containing epoxy resin composition comprising the above epoxy resin composition and reinforcing fibers, and a prepreg comprising the above reinforcing fiber-containing epoxy resin composition. The reinforcing fibers are preferably PAN-based or pitch-based carbon fibers.

The present invention also relates to a fiber-reinforced plastic using the reinforcing fiber-containing epoxy resin composition, and a fiber-reinforced plastic using the prepreg.

The present invention also provides a thermoplastic obtained from the epoxy resin composition, having a weight average molecular weight of 35,000 or more and 200,000 or less, and an impact strength of 48 kJ/m ² or more as measured by an unnotched Izod impact test. , is a thermoplastic having a glass transition temperature of 120° C. or higher.

The epoxy resin composition of the present invention can provide fiber reinforced plastics (FRP) with excellent heat resistance and impact resistance.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to its preferred embodiments.
The epoxy resin composition of the present invention contains a bifunctional acetyl compound, an epoxy resin, and a polymerization catalyst as essential components, and is polymerized by heating to form a thermoplastic. This composition may contain additives such as bifunctional phenol compounds, organic solvents, fillers and flame retardants.

好ましくは６６重量％以上であり、より好ましくは７５重量％以上であり、更に好ましくは８０重量％以上である。エポキシ樹脂（ａ）はエポキシ樹脂の一部を構成する。
ｎは繰り返し数でその平均値は０～５であり、好ましくは０～１である。また、エポキシ樹脂（ａ）のエポキシ当量は、１５０～３５０ｇ／ｅｑ．が好ましい。エポキシ樹脂（ａ）の純度は９５％以上であることが好ましい。 The epoxy resin used in the epoxy resin composition contains 50% by weight or more of the epoxy resin (a) represented by formula (1) as an essential component.

It is preferably 66% by weight or more, more preferably 75% by weight or more, and still more preferably 80% by weight or more. Epoxy resin (a) constitutes a part of the epoxy resin.
n is the number of repetitions, and its average value is 0-5, preferably 0-1. Also, the epoxy equivalent of the epoxy resin (a) is 150 to 350 g/eq. is preferred. The purity of the epoxy resin (a) is preferably 95% or more.

In formula (1), A is a divalent group represented by formula (2).

In formula (2), X is a single bond, a hydrocarbon group having 1 to 13 carbon atoms, -O-, -CO-, -COO-, -S- or -SO ₂ -.
The hydrocarbon group having 1 to 13 carbon atoms is preferably an alkylene group having 1 to 9 carbon atoms or an arylene group having 6 to 13 carbon atoms, such as —CH ₂ —, —CH(CH ₃ )—, —C( CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, —CHPh—, —C(CH ₃ )Ph—, 1,1-cyclopropylene group, 1,1-cyclobutylene group, 1,1-cyclopentyl rene group, 1,1-cyclohexylene group, 4-methyl-1,1-cyclohexylene group, 3,3,5-trimethyl-1,1-cyclohexylene group, 1,1-cyclooctylene group, 1, 1-cyclononylene group, 1,2-ethylene group, 1,2-cyclopropylene group, 1,2-cyclobutylene group, 1,2-cyclopentylene group, 1,2-cyclohexylene group, 1,2-phenylene group, 1,3-propylene group, 1,3-cyclobutylene group, 1,3-cyclopentylene group, 1,3-cyclohexylene group, 1,3-phenylene group, 1,4-butylene group, 1, 4-cyclohexylene group, 1,4-phenylene group, 1,1-fluorene group, 1,2-xylylene group, 1,4-xylylene group, tetrahydrodicyclopentadienylene group, tetrahydrotricyclopentadienylene group, etc. is mentioned. In addition, Ph represents a phenyl group.
Among these, single bond, —O—, —CO—, —COO—, —S—, —SO ₂ —, —CH ₂ —, —CH(CH ₃ )—, —C(CH ₃ ) ₂ —, —CHPh—, —C(CH ₃ )Ph—, 1,1-cyclohexylene group, 4-methyl-1,1-cyclohexylene group, 3,3,5-trimethyl-1,1-cyclohexylene group, 1 ,4-cyclohexylene group, 1,4-phenylene group and 1,1-fluorene group are preferred, single bond, -O-, -CO-, -COO-, -S-, -SO ₂ -, -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CH ₃ )Ph-, 1,1-cyclohexylene group, 3,3,5-trimethyl-1,1-cyclohexylene A 1,1-fluorene group is more preferred. In addition, Ph represents a phenyl group. An alkylene group is meant to include an alkylidene group.

Y ¹ is independently either an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 10 carbon atoms.
Examples of alkyl groups having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, iso-butyl group and t-butyl group. mentioned.
Examples of the aryl group having 6 to 10 carbon atoms include phenyl group, tolyl group, ethylphenyl group, xylyl group, n-propylphenyl group, isopropylphenyl group, mesityl group and naphthyl group.
Among these, methyl group, ethyl group, n-propyl group, n-butyl group, t-butyl group, phenyl group, tolyl group, xylyl group or naphthyl group are preferred, and methyl group, ethyl group and n-propyl group. , n-butyl group, t-butyl group, phenyl group, or tolyl group are more preferred.

Y ² is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and is preferably a group other than a hydrogen atom. Examples of the alkyl group and the aryl group are the same as the groups exemplified for Y ¹ above. Preferred ^Y2 is the same as ^Y1 .
Y ³ is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Examples of the alkyl group and aryl group are the same as the groups exemplified for ^Y1 . Preferred ^Y3 is a hydrogen atom or the same as ^Y1 .

As the epoxy resin (a), for example, tetramethylbisphenol F type epoxy resin (eg, YSLV-80XY (manufactured by Nippon Steel Chemical & Materials Co., Ltd.), etc.), tetramethylbiphenol type epoxy resin (eg, YX-4000 (Mitsubishi Chemical Co., Ltd.), etc.), biscresol fluorene type epoxy resins (eg, OGSOL CG-500 (manufactured by Osaka Gas Chemicals Co., Ltd.), etc.).

Epoxy resins other than the epoxy resin (a) can also be used in combination with other bifunctional epoxy resins in a range of less than 50% by weight based on the total epoxy resin, as long as the effects of the present invention are not impaired. Its purity is preferably 95% or higher. If the purity as a bifunctional epoxy resin is high, positional isomers and oligomers may be included.
Examples of epoxy resins that can be used in combination with the epoxy resin (a) include bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol S-type epoxy resin, bisphenolacetophenone-type epoxy resin, diphenyl sulfide-type epoxy resin, diphenyl ether-type epoxy resin, and bisphenol. Bisphenol-type epoxy resins such as fluorene-type epoxy resins, biphenol-type epoxy resins, diphenyldicyclopentadiene-type epoxy resins, alkylene glycol-type epoxy resins, dihydroxynaphthalene-type epoxy resins, dihydroxybenzene-type epoxy resins, etc., can be mentioned. Not exclusively.

The epoxy resin used in the epoxy resin composition of the present invention is desirably mainly composed of bifunctional components.
When monofunctional impurities are contained in the epoxy resin, the molecular weight after polymerization does not increase, and the resulting thermoplastic resin product may have poor mechanical properties. Therefore, the content of monofunctional impurities is preferably 2% by weight or less with respect to the bifunctional epoxy resin.
If tri- or higher-functional impurities are contained, a crosslinked structure is likely to be formed starting from the impurities, which may increase the dispersion of the polymer and may cause gelation to impair thermoplasticity. Therefore, it is preferable that the tri- or higher-functional impurities be 1% by weight or less relative to the difunctional epoxy resin.

The bifunctional acetyl compound used in the epoxy resin composition of the present invention is a compound having two acetyl groups in one molecule. Its purity is preferably 95% by weight or more. If the purity as a bifunctional acetyl compound is high, positional isomers may be contained.
When monofunctional impurities are contained, the molecular weight after polymerization does not increase, so that the produced thermoplastic resin may have poor mechanical properties. Therefore, the content of monofunctional impurities is preferably 2% by weight or less with respect to the bifunctional acetyl compound.
If tri- or higher-functional impurities are contained, a crosslinked structure is likely to be formed starting from the impurities, which may increase the dispersion of the polymer and may cause gelation to impair thermoplasticity. Therefore, trifunctional or higher functional impurities are preferably 1% by weight or less with respect to the bifunctional acetyl compound.

An impurity component that does not have an active group that reacts with either the epoxy resin or the acetyl compound and that does not inhibit the polymerization reaction by itself may decrease the molecular weight after polymerization if the amount thereof increases. Therefore, it is preferably 2% by weight or less for both the bifunctional epoxy resin and the bifunctional acetyl compound.
The total amount of impurity components in the bifunctional acetyl compound is preferably 5% by weight or less, more preferably 3% by weight or less.

A bifunctional acetyl compound can be easily obtained by reacting a bisphenol compound or a bifunctional phenol compound such as a biphenol compound as a starting material with acetic anhydride.
Examples of bisphenol compounds include bisphenol A, bisphenol F (manufactured by Nippon Steel Chemical & Materials Co., Ltd.), bisphenol fluorene (manufactured by Osaka Gas Chemicals Co., Ltd.), Bis-E, Bis-Z, BisOC-FL, BisP- AP, BisP-CDE, BisP-HTG, BisP-MIBK, BisP-3MZ, S-BOC (manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol S and the like. Examples of biphenol compounds include biphenol, dimethylbiphenol, tetramethylbiphenol and the like. Examples of other bifunctional phenol compounds include benzenediols such as hydroquinone, methylhydroquinone, dibutylhydroquinone, resorcinol, methylresorcinol, catechol and methylcatechol, and naphthalene diols such as naphthalene diol. For the purpose of imparting flame retardancy, 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Chemical Co., Ltd.) is used as a phenol compound. , HCA-HQ) may also be used. The bifunctional acetyl compound may be obtained by acetylating a phenol compound, or may be synthesized by other methods.

ここで、Ｘ、Ｙ^１、Ｙ^２及びＹ^３は上記式（２）のＸ、Ｙ^１、Ｙ^２及びＹ^３と同義である。 Examples of bifunctional acetyl compounds include compounds represented by the following formula (3).

Here, X, Y ¹ , Y ² and Y ³ are synonymous with X, Y ¹ , Y ² and Y ³ in formula (2) above.

The bifunctional acetyl compound may be a phosphorus-containing acetyl compound, and examples of phosphorus-containing acetyl compounds include diacetylated cyclic phosphorus compounds (HCA-HQ) represented by the following formula (4).

In the epoxy resin composition of the present invention, a part of the bifunctional acetyl compound may be replaced with a bifunctional phenol compound in order to adjust the viscosity, solubility, reactivity and physical properties of the polymer. By dissolving a plurality of components, the effect of suppressing reprecipitation due to crystallization and improving the solubility is expected.
A bisphenol compound or a biphenyl compound is preferable as the bifunctional phenol compound. Examples of bisphenol compounds include bisphenol A, bisphenol F (manufactured by Nippon Steel Chemical & Materials Co., Ltd.), bisphenol fluorene (manufactured by Osaka Gas Chemicals Co., Ltd.), Bis-E, Bis-Z, BisOC-FL, BisP- AP, BisP-CDE, BisP-HTG, BisP-MIBK, BisP-3MZ, S-BOC (manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol S and the like. Examples of biphenol compounds include biphenol, dimethylbiphenol, tetramethylbiphenol and the like. Examples of other bifunctional phenol compounds include benzenediols such as hydroquinone, methylhydroquinone, dibutylhydroquinone, resorcinol, methylresorcinol, catechol and methylcatechol, and naphthalene diols such as naphthalene diol. A phosphorus-containing phenol compound may also be used for the purpose of imparting flame retardancy.

When the epoxy resin composition of the present invention contains a bifunctional phenol compound, the ratio of the bifunctional phenol compound is preferably 40% by weight or less, more preferably 5 to 20% by weight, based on the total composition. If it exceeds 40% by weight, the proportion of the bifunctional acetyl compound will decrease, and there is a risk that the heat resistance will not be improved.

In the epoxy resin composition of the present invention, the ratio of the epoxy resin is 0.95 per 1 mol of the bifunctional acetyl compound (when the bifunctional phenol compound is contained, the bifunctional acetyl compound and the bifunctional phenol compound). It is up to 1.05 mol, preferably 1.00 to 1.05 mol, more preferably 1.02 to 1.03 mol.
In the epoxy resin composition of the present invention, the epoxy resin and the acetyl compound or the phenol compound react successively to form a straight chain structure, thereby exhibiting thermoplasticity. If the epoxy resin is excessive, the epoxy group will be terminated, and if the acetyl compound is excessive, the acetyl group will be terminated and the reaction will be terminated.
If the proportion of the epoxy resin is less than 1.01 mol, the polymer will end up with an acetyl group and the reaction will end, which may make it difficult to increase the molecular weight. On the other hand, if the proportion of the epoxy resin exceeds 1.05 mol, excess epoxy groups may cause side reactions, resulting in gelation of the polymer and loss of thermoplasticity.

In the epoxy resin composition, if the acetyl compound (and phenolic compound) is present in the epoxy resin in a crystalline state, the molar ratio deviates from the design when viewed microscopically. If the reaction is started in this state, the polymerization may not progress sufficiently. An epoxy resin composition in which the acetyl compound (and the phenol compound) and the epoxy resin are uniformly compatible with each other is preferable for sufficiently progressing the polymerization.
In addition, it is desirable that the epoxy resin composition is completely dissolved or in a uniform liquid state before the reinforcing fiber is blended. When the haze value in the thickness direction is measured by adding the molten mixture, if the haze value in the thickness direction is less than 30%, it is determined that the mixture has dissolved or become a uniform liquid to a level that does not affect the polymerization reaction. The haze value is more preferably less than 20%, still more preferably less than 10%.

The epoxy resin composition of the present invention contains a polymerization catalyst as an essential component. Specific examples of the polymerization catalyst include amine compounds such as 4-dimethylaminopyridine, triethylamine and tributylamine, imidazole compounds such as 4-methylimidazole, 1B2MZ, 1B2PZ, and TBZ (manufactured by Shikoku Kasei Kogyo), triphenylphosphine, Phosphorus compounds such as tris(para-toluyl)phosphine, tris(orthotoluyl)phosphine, tris(paramethoxyphenyl)phosphine, quaternary ammonium salts such as tetramethylammonium chloride and tetramethylammonium bromide, 18-crown-6(18 -C-6)/AcOK complex, crown ether complexes such as 18-C-6/KF complex, and metal chlorides. Preferred are amine compounds such as 4-dimethylaminopyridine, triethylamine and tributylamine.

The blending amount of the polymerization catalyst is desirably 0.01% by weight or more and 5% by weight or less with respect to the total amount of the resin composition comprising the epoxy resin and the bifunctional acetyl compound (and the bifunctional phenol compound). If the content is less than 0.01% by weight, in situ polymerization may take a long time, resulting in a decrease in productivity, and there is also a risk of deactivation for some reason before the target molecular weight is reached. On the other hand, if it exceeds 5% by weight, while the polymerization reaction proceeds rapidly, the storage stability may be impaired, which may cause problems with process compatibility. Therefore, there is a possibility that the physical properties after polymerization may be impaired, and it is simply expensive, which is economically disadvantageous. More preferably 0.05 to 1.0% by weight.

The epoxy resin composition of the present invention desirably does not contain an organic solvent, but if necessary, it may contain an organic solvent as a solvent for the polymerization catalyst or for viscosity adjustment. The organic solvent is not particularly limited as long as it does not inhibit the reaction between the epoxy resin and the acetyl compound (and phenol compound). is preferred. Specific examples include toluene, xylene, acetone, methyl ethyl ketone, isobutyl ketone, cyclopentanone, cyclohexanone, and diethylene glycol dimethyl ether. However, if a large amount of organic solvent is present during the reaction, the polymerization reaction will be inhibited, and if the organic solvent remains in the polymer, the mechanical properties and heat resistance will be deteriorated. Therefore, when an organic solvent is blended, its proportion in the epoxy resin composition is 10% by weight or less, preferably 5% by weight or less, and particularly preferably 2% by weight or less.

The progress of the polymerization of the epoxy resin composition of the present invention can be judged by transition of the weight average molecular weight of the polymer. If the heating is performed for less than 1 hour, the weight average molecular weight tends to increase, and the polymerization may not proceed sufficiently. After heating for 1 hour or more, the epoxy equivalent did not substantially increase from the value at the time of 1 hour, and it can be judged that the polymerization proceeded sufficiently. Accordingly, the polymerization conditions for obtaining the thermoplastic polymer from the epoxy resin composition are preferably, for example, heating at 180° C. for 1 hour. Here, the physical property values of the polymer are the measured values of those polymerized under these conditions.

The weight average molecular weight (Mw) of the polymer obtained by polymerizing the epoxy resin composition of the present invention is 35000 or more and 200000 or less. If the weight-average molecular weight of the polymer is less than the lower limit of the range, the polymer may contain a large amount of compounds whose polymerization has not progressed sufficiently, resulting in deterioration in mechanical strength. On the other hand, when the weight average molecular weight of the polymer exceeds the upper limit of the range, the cross-linking reaction may proceed and the thermoplasticity may be impaired. Mw is preferably 35,000 or more and 100,000 or less, more preferably 40,000 or more and 70,000 or less. The epoxy equivalent of the polymer is 10000 g/eq. It is desirable to be above. Epoxy equivalent is 10,000 g/eq. If it is less than that, the polymerization may not proceed sufficiently. The epoxy equivalent is preferably 20,000 g/eq. above, more preferably 25,000 g/eq. That's it. The glass transition temperature (Tg) of the polymer is preferably 120°C or higher, more preferably 125°C or higher.

The impact strength of the polymer is evaluated by the non-notched Izod impact test (specifically, the measurement method described in the Examples), and the impact strength must be 48 kJ/m ² or more. For the sake of convenience, when the sample did not break in the same test, the breaking strength was judged to be 48 kJ/m ² or more. Preferred impact strength is non-breaking.

The epoxy resin composition of the present invention can contain additives. Examples of additives include fillers such as fumed silica, flame retardants such as aluminum hydroxide and red phosphorus, modifiers such as core-shell rubber, and viscosity modifiers such as xylene resin. From the viewpoint of stabilizing the polymerization reaction, it is desirable to add an additive different from the resin phase, but a plasticizer and a compatible flame retardant may be included as long as they do not affect the reaction.

The epoxy resin composition of the present invention becomes a thermoplastic by polymerizing it. This thermoplastic epoxy resin is excellent as a resin component for fiber-reinforced plastics.
The reinforcing fiber-containing epoxy resin composition of the present invention is obtained by mixing or impregnating the above epoxy resin composition and reinforcing fibers. Also, the prepreg can be obtained as follows.

An epoxy resin composition film can be obtained by applying the epoxy resin composition of the present invention to a release-treated paper or plastic film and, if necessary, providing a release-treated cover film. can. As for the release paper, release plastic film, and cover film, known ones can be used, and they are not particularly limited. The thickness of the epoxy resin composition film is determined by the design thickness of the prepreg and the resin ratio, but the normal thickness is 1 μm or more and 300 μm or less. When the thickness is less than 1 μm, there is a problem that the opening of the fibers becomes conspicuous unless the reinforcing fibers are defibrated cleanly. It is preferably 5 μm or more and 150 μm or less, more preferably 10 μm or more and 100 μm or less.

The reinforcing fibers used in the present invention are for reinforcing plastics such as carbon fibers, aramid fibers, and cellulose fibers, and are not particularly limited. Also, the form of the fibers is not particularly limited and includes UD sheets, woven fabrics, tows, chopped fibers, non-woven fabrics, papermaking, and the like. However, from the viewpoint of impregnation, the thickness of each fiber bundle is 1 mm or less, preferably 0.5 mm or less, more preferably 0.2 mm or less.

The reinforcing fiber-containing epoxy resin composition or prepreg of the present invention is obtained from the above epoxy resin composition and/or epoxy resin composition film and reinforcing fibers. The weight ratio of the reinforcing fiber to the epoxy resin composition is preferably 5:5 to 8:2. If the ratio of the reinforcing fibers is too small, the strength required of the fiber-reinforced material may not be sufficiently satisfied, and if the reinforcing fibers are too large, defects such as voids may occur.

EXAMPLES The present invention will be described in more detail based on examples below, but the present invention is not limited to the following examples. "Parts" means parts by weight and "%" means % by weight unless otherwise specified.

Raw materials, catalysts, solvents, and reinforcing fibers used in the examples are as follows.
[Epoxy resin]
A1: Tetramethylbiphenol type epoxy resin (Mitsubishi Chemical Corporation, YX-4000, epoxy equivalent 186)
A2: Bisphenol A type epoxy resin (manufactured by Nippon Steel Chemical & Materials Co., Ltd., YD-8125, epoxy equivalent 173)

Ｂ２：合成例２で得られたジアセチル化合物（フェノールフタレインジアセタート、アセチル基当量２０１）

Ｂ３：合成例３で得られたジアセチル化合物（１０－（２，５－ジアセトキシフェニル）－９，１０－ジヒドロ９－オキサ－１０－ホスファフェナントレン－１０－オキサイド、式（４）で表されるリン化合物、アセチル基当量２０４）
Ｂ４：４，４’－ジアセトキシビフェニル（東京化成工業株式会社製、アセチル基当量１３５）

Ｂ５：２，２－ビス（４－アセトキシフェニル）プロパン（東京化成工業株式会社製、アセチル基当量１５６）

[Acetyl compound]
B1: Diacetyl compound obtained in Synthesis Example 1 (4,4′-bis(3,3,5-trimethylcyclohexylidene) bisphenol diacetate, acetyl group equivalent 197)

B2: diacetyl compound obtained in Synthesis Example 2 (phenolphthalein diacetate, acetyl group equivalent 201)

B3: Diacetyl compound obtained in Synthesis Example 3 (10-(2,5-diacetoxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, represented by formula (4) phosphorus compound, acetyl group equivalent 204)
B4: 4,4'-diacetoxybiphenyl (manufactured by Tokyo Chemical Industry Co., Ltd., acetyl group equivalent 135)

B5: 2,2-bis(4-acetoxyphenyl)propane (manufactured by Tokyo Chemical Industry Co., Ltd., acetyl group equivalent 156)

Ｃ４：フェノールフタレイン（東京化成工業株式会社製、水酸基当量１５９）

Ｃ５：ビスフェノールフルオレン（東京化成工業株式会社製、水酸基当量１８９）

Ｃ６：１０－（２，５－ジヒドロキシフェニル）－９，１０－ジヒドロ－９－オキサ－１０－ホスファフェナントレン－１０－オキサイド（三光株式会社製、ＨＣＡ－ＨＱ、水酸基当量１６２）

[Phenolic compound]
C1: Bisphenol A (manufactured by Nippon Steel Chemical & Materials Co., Ltd., hydroxyl equivalent 114)
C2: Bisphenol F (manufactured by Nippon Steel Chemical & Materials Co., Ltd., SP2000P, hydroxyl equivalent 100)
C3: 4,4′-bis(3,3,5-trimethylcyclohexylidene) bisphenol (manufactured by Honshu Chemical Industry Co., Ltd., BisP-HTG, hydroxyl equivalent 155)

C4: phenolphthalein (manufactured by Tokyo Chemical Industry Co., Ltd., hydroxyl equivalent 159)

C5: Bisphenol fluorene (manufactured by Tokyo Chemical Industry Co., Ltd., hydroxyl equivalent 189)

C6: 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Co., Ltd., HCA-HQ, hydroxyl equivalent 162)

[Polymerization catalyst]
D1: 4-dimethylaminopyridine (DMAP, manufactured by Tokyo Chemical Industry Co., Ltd.)

Evaluation methods in the examples are as follows.

Compatibility:
Whether the acetyl compound and the phenol compound were uniformly melted in the epoxy resin was determined by the haze value. Specifically, the epoxy resin composition was placed in a colorless and transparent glass Petri dish so as to have a thickness of 2 mm, and the haze value was adjusted to "less than 5% (<5)" with reference to a haze standard plate manufactured by Murakami Color Research Laboratory. "5% to less than 10% (<10)""10% to less than 20% (<20)""20% to less than 30% (<30)""30% or more (30<)" evaluated. If the haze value is less than 30%, it can be determined that the acetyl compound and the phenol compound are uniformly dissolved in the epoxy resin.

Epoxy equivalent weight:
The measurement was performed according to the JIS K7236 standard, and the unit was expressed as "g/eq.". Specifically, a potentiometric titrator was used, chloroform was used as a solvent, a tetraethylammonium bromide acetic acid solution was added, and a 0.1 mol/L perchloric acid-acetic acid solution was used.

Molecular weight:
Weight average molecular weight (Mw) and number average molecular weight (Mn) were determined by GPC measurement. Specifically, a column (TSKgel SuperH-H, SuperH2000, SuperHM-H, SuperHM-H, manufactured by Tosoh Corporation) is used in series with the main body HLC8320GPC (manufactured by Tosoh Corporation), and the column temperature is The temperature was brought to 40°C. Tetrahydrofuran (THF) was used as an eluent at a flow rate of 0.3 mL/min, and a differential refractive index detector was used as a detector. As a measurement sample, 0.1 g of solid content was dissolved in 10 mL of THF, filtered through a 0.45 μm microfilter, and 20 μL of the solution was used. Mw and Mn were obtained by converting from a calibration curve obtained from standard polystyrene (manufactured by Tosoh Corporation, PStQuick A, PStQuick B, PStQuick C). For data processing, GPC8020 model II version 6.00 manufactured by Tosoh Corporation was used.

Glass transition temperature (Tg):
According to JIS K7121, DSC Tmg (tangent line between glass state and rubber state It was expressed as the temperature of the middle temperature of the mutation curve for ).

Solvent solubility of polymer:
About 1 g of the sample was accurately weighed into a 100 mL vial, 50 mL of tetrahydrofuran was added, ultrasonic diffusion was performed at room temperature for 1 hour, and the mixture was left standing at room temperature for 23 hours or more to dissolve. Solvent solubility was evaluated as ◯ when the polymer dissolved in the solvent and no solid matter was observed. When a gel state was observed due to undissolved portions, the sample was evaluated as Δ. When the polymer did not dissolve in the solvent, it was marked as x.

Impact strength:
The impact strength was measured according to the JIS K7110 non-notched Izod impact test. A digital impact tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used as the tester. When the lifting angle was set to 150° and the idling angle was measured, it was 147.5°. As for the hammer, a hammer that gave an impact energy of 2 J to the sample under the condition of the lifting angle was used. The dimensions of the sample were 4 mm thick, 80 mm long and 10 mm wide. When a hammer was dropped on the sample and the sample was destroyed, the impact strength was calculated from the swing angle of the hammer after the measurement. If the sample did not break, it was recorded as NB and judged to have an impact strength of 48 KJ/m ² or greater.

Synthesis example 1
155 parts of bifunctional phenol compound C3, 105 parts of acetic anhydride and 79 parts of pyridine are charged at room temperature into a glass reaction vessel equipped with a stirring device, thermometer, nitrogen gas introduction device, cooling tube and dropping device, The temperature was raised to 60° C. while nitrogen gas was flowed and the mixture was stirred, and the reaction was carried out for 2 hours. Then, it was dried under reduced pressure for 2 hours under conditions of 150° C. and 1.3 kPa (10 torr) to obtain diacetyl compound B1.

Synthesis example 2
A diacetyl compound B2 was obtained in the same manner as in Synthesis Example 1, except that 155 parts of C3 was changed to 159 parts of C4 as the bifunctional phenol compound.

Synthesis example 3
A diacetyl compound B3 was obtained in the same manner as in Synthesis Example 1, except that 155 parts of C3 was changed to 162 parts of C6 as the bifunctional phenol compound.

Example 1
96 parts of A1 and 100 parts of B1 were weighed, pulverized and mixed using a Henschel mixer, and sealed in a metal can. Subsequently, the metal can was placed in a hot-air circulating oven preheated to 170° C. for 30 minutes to dissolve the resin, and then cooled to room temperature to obtain a precursor mixture of an epoxy resin composition. The haze value of the obtained precursor mixture was 5% or more and less than 10% (<10), and it was judged that the precursor mixture was uniformly dissolved.

100 parts of the precursor mixture preheated to 80° C. is weighed into a disposable cup, 0.1 part of polymerization catalyst D1 is added, and a rotation/revolution mixer (Awatori Mixer, ARV-310, manufactured by Shinki Co., Ltd.) is used. was mixed for 2 minutes under vacuum conditions (degree of vacuum 4 kPa) at a rotation speed of 2000 rpm. After mixing, the mixture was quickly withdrawn and immediately cooled to 40° C. or lower to obtain an epoxy resin composition E1.

The resulting epoxy resin composition E1 was heated to about 80°C with stirring, poured into an iron chromium-plated mold container with a clearance of 4 mm in advance, and thermally polymerized at 180°C for 60 minutes in a hot air circulating oven. , to obtain a polymer.
The resulting polymer had an epoxy equivalent of 30,000 g/eq. , Mw was 46,000, Mn was 9,000, Tg was 130° C., and the solvent solubility was ◯. Moreover, the impact strength was NB (not broken).

Examples 2-10, Comparative Examples 1-10
Example in which precursor mixtures, epoxy resin compositions (E2 to E10, EH1 to EH10), and polymers were obtained by blending in the amounts (parts) of the formulations shown in Tables 1 and 2 and performing the same operations as in Example 1. 1 and the evaluation results are shown in Tables 1 and 2. The "molar ratio" in the table represents the equivalent ratio of the epoxy groups of the epoxy resin to the functional groups of the acetyl and phenolic compounds.
The polymers obtained in Examples 1 to 8 were remelted by heating at 200° C. for 5 minutes, and could be easily bent, confirming that they were thermoplastic epoxy resins. rice field. In Comparative Examples 1 and 3 to 6, the haze value of the resin composition was 30% or more (30<), and a polymer with non-uniform color was obtained after the polymerization reaction. Further, since the solvent solubility of the polymers of Comparative Examples 1, 3 to 7, and 9 was poor, the epoxy equivalent was not measured. Molecular weight measurements were performed only on the eluted components.

Claims (11)

An epoxy resin composition that contains a bifunctional epoxy resin, a bifunctional acetyl compound, and a polymerization catalyst as essential components and that becomes a thermoplastic through a polymerization reaction,
50% by weight or more of the bifunctional epoxy resin is the epoxy resin (a) represented by the following formula (1), and the bifunctional epoxy resin is 0.95 to 1.05% per 1 mol of the bifunctional acetyl compound. The bifunctional acetyl compound is uniformly dissolved in the bifunctional epoxy resin, and the weight average molecular weight of the polymer obtained by polymerizing the epoxy resin composition is 35,000 or more and 200,000 or less. , an epoxy resin composition having an impact strength of 48 kJ/m ² or more as measured by an unnotched Izod impact test.

(Here, A is a divalent group represented by formula (2), n is the number of repetitions, and its average value is 0 to 5. X is a single bond, a carbonized group having 1 to 13 carbon atoms, a hydrogen group, —O—, —CO—, —COO—, —S—, or —SO ₂ —, and Y ¹ is independently an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 10 carbon atoms and Y ² and Y ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbon atoms.) Furthermore, a bifunctional phenol compound is included, and the molar ratio of the bifunctional acetyl compound and the bifunctional phenol compound is 1/99 to 99/1. 2. The epoxy resin composition according to claim 1, wherein the epoxy resin is 0.95 to 1.05 mol, and the bifunctional acetyl compound and the bifunctional phenol compound are uniformly dissolved in the epoxy resin. 3. The epoxy resin composition according to claim 2, wherein the content of the bifunctional phenol compound is 5% by weight or more and 40% by weight or less of the epoxy resin composition. 4. The epoxy resin composition according to any one of claims 1 to 3, wherein the epoxy resin composition does not contain an organic solvent, or when it contains an organic solvent, the content of the organic solvent is 0.05% by weight or more and 10% by weight or less of the epoxy resin composition. The epoxy resin composition described. 5. The epoxy resin composition according to any one of claims 1 to 4, wherein the polymer has a glass transition temperature of 120°C or higher. A reinforcing fiber-containing epoxy resin composition comprising the epoxy resin composition according to any one of claims 1 to 5 and reinforcing fibers. 7. The epoxy resin composition containing reinforcing fibers according to claim 6, wherein the reinforcing fibers are PAN-based or pitch-based carbon fibers. A prepreg comprising the reinforcing fiber-containing epoxy resin composition according to claim 6 or 7. A fiber-reinforced plastic using the reinforcing fiber-containing epoxy resin composition according to claim 6 or 7. A fiber-reinforced plastic using the prepreg according to claim 8. A thermoplastic obtained from the epoxy resin composition according to any one of claims 1 to 5, having a weight average molecular weight of 35,000 or more and 200,000 or less, and an impact measured by an unnotched Izod impact test. A thermoplastic having a strength of 48 kJ/m ² or more and a glass transition temperature of 120° C. or more.