JP2024005422A - Epoxy resin composition, prepreg and fiber-reinforced plastic including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition that has a sufficiently long pot life before the reaction, allows the polymerization reaction to sufficiently progress, and becomes a thermoplastic epoxy resin through its reaction; a reinforced fiber-containing epoxy resin composition that includes the same; a prepreg; and a fiber-reinforced plastic including the same.

SOLUTION: A reinforced fiber-containing epoxy resin composition includes an epoxy resin composition that include a bifunctional epoxy compound, a bifunctional compound and a polymerization catalyst as essential components and becomes a thermoplastic epoxy resin through a polymerization reaction, and reinforced fibers. The polymerization catalyst is a phosphonium salt represented by the general formula (1) (where R¹, R², R³, R⁴, R⁵ and R⁶ each represent an alkyl group, an aryl group or an aralkyl group, and Z represents an oxygen atom or a sulfur atom).

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to epoxy resin compositions, prepregs, and fiber reinforced plastics using these.

Fiber-reinforced plastics (FRP) exhibit excellent physical properties such as light weight and high strength, and are used in many fields. Among these, those using carbon fibers as reinforcing fibers (CFRP) are known to have particularly excellent mechanical strength.

Epoxy resins are mainly used as matrix resins for FRP due to their excellent balance between price and physical properties. Among them, Patent Document 1 discloses that epoxy resins and phenolic hydroxyl group-containing compounds are pre-coated with reinforcing fibers. This paper proposes a method of molding a fiber-reinforced thermoplastic resin by mixing it with a polymer and polymerizing it by a polyaddition reaction using a polymerization catalyst and a reaction retarder. Patent Document 2 discloses 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 in-situ polymerizable thermoplastic epoxy resins, and FRP using them is expected to be excellent in mass production, moldability, and recyclability. In-situ polymerization type thermoplastic epoxy resin has good impregnation properties because it is impregnated into fibers in a low viscosity state before polymerization, and the proportion of reinforcing fibers can be increased, resulting in higher impact strength and toughness than general-purpose thermosetting epoxy resins. Excellent in

One of the required characteristics of FRP is improved heat resistance. Heat resistance of 120° C. or higher is useful because it expands the range of members to which it can be applied. Methods for improving the heat resistance of epoxy resins include increasing crosslink density and applying a rigid molecular skeleton. An increase in crosslink density is not suitable for in-situ polymerizable thermoplastic epoxy resins, which are thermoplastic resins. A change to a rigid skeleton results in an increase in resin viscosity and a deterioration in the compatibility of reaction components. This makes coating the resin film and impregnating the fibers difficult, and also reduces the reactivity within the fibers.

Addition of a solvent or raising the handling temperature of the resin can be cited as a method for reducing the viscosity of a resin having a rigid molecular structure and facilitating the process of coating a resin film or impregnating reinforcing fibers. Addition of a solvent reduces the physical properties of the final product by remaining in the polymer. As the handling temperature increases, the reaction rate of the resin increases, which shortens the pot life and makes handling difficult.

Although it is possible to extend the pot life of the resin by reducing the amount of polymerization catalyst added, there is a risk that the reactivity will deteriorate and the on-site polymerization will take time, reducing productivity. There is a risk that the activity will be deactivated for some reason before reaching the molecular weight of .

The example of Patent Document 3 describes an in-situ polymerization type thermoplastic epoxy using a phosphine-based polymerization catalyst and increasing the Tg to 139°C, but the resin composition contains 30 parts by weight or more of a solvent. There is a concern that the solvent may remain in the polymer and adversely affect the physical properties.
In Patent Document 4, an amine polymerization catalyst is considered as a polymerization catalyst, but there is no description regarding pot life.

Japanese Patent Application Publication No. 2006-321897 International Publication No. 2004/060981 International Publication No. 2006/123577 International Publication No. 2010/079832

The problem of the present invention is to obtain a thermoplastic epoxy resin by reacting a bifunctional epoxy resin with a compound having two phenolic hydroxyl groups and/or active ester groups as functional groups in one molecule. An object of the present invention is to provide an epoxy resin composition, a prepreg, and a fiber-reinforced plastic using the same, which can be used for a sufficiently long time and allow a sufficient polymerization reaction to proceed.

As a result of intensive studies to solve the above problems, the present inventors found that a bifunctional epoxy resin and a compound having two phenolic hydroxyl groups and/or active ester groups as functional groups in one molecule were used as raw materials to generate heat. The inventors have discovered that the above problems can be solved by using a specific phosphonium salt as a polymerization catalyst when obtaining a plastic epoxy resin, leading to the completion of the invention.
In addition, by using a specific phosphonium salt as a polymerization catalyst, sufficient pot life can be secured even if the amount of polymerization catalyst is increased, and the time required for on-site polymerization is significantly shortened, resulting in excellent productivity. I found out.

式中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５及びＲ^６は、それぞれ独立して、アルキル基、アリール基又はアラルキル基を表し、同一の基であっても異なる基であってもよい。Ｚは酸素原子又は硫黄原子を表す。 That is, the present invention provides an epoxy compound (A) having two epoxy groups in the molecule, a compound (B) having two phenolic hydroxyl groups and/or active ester groups (acyloxy groups) as functional groups in one molecule, and This is an epoxy resin composition that contains a polymerization catalyst (C) as an essential component and becomes a thermoplastic plastic through a polymerization reaction, and the polymerization catalyst (C) is a phosphonium salt represented by the following general formula (1).

In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent an alkyl group, an aryl group or an aralkyl group, and even if they are the same group, they may be different groups. Good too. Z represents an oxygen atom or a sulfur atom.

The epoxy resin composition (E) does not contain an organic solvent, or if 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, It is preferable that the epoxy resin composition has a viscosity of 100 Pa·s or less when heated to 85°C.
The blending amount of the above epoxy compound (A) and the above compound (B) is preferably 0.95 to 1.05 mol of the compound (B) per 1 mol of the epoxy compound (A), and the above polymerization catalyst ( The blending amount of C) is preferably 0.5 to 10 parts by weight per 100 parts by weight of the epoxy compound (A).
Part or all of the epoxy compound (A) and/or the compound (B) may be a phosphorus-containing compound, and in that case, the phosphorus content is 1 to 6% by weight as the epoxy resin composition. It is preferable.

The present invention is a reinforcing fiber-containing epoxy resin composition characterized by containing the above-mentioned epoxy resin composition (E) and reinforcing fibers (F). The reinforcing fiber (F) is preferably carbon fiber, and is preferably contained in a proportion of 50 to 80% by weight.

The present invention also provides a prepreg comprising the reinforcing fiber-containing epoxy resin composition.
Further, the present invention is a fiber-reinforced plastic using the above-mentioned reinforcing fiber-containing epoxy resin composition, and a fiber-reinforced plastic using the above-mentioned prepreg.

The epoxy resin composition of the present invention can provide a thermoplastic fiber-reinforced plastic (FRP) that has high heat resistance, excellent mechanical strength, completes the polymerization reaction in a short time, and has excellent productivity.

Hereinafter, the present invention will be explained in detail based on its preferred embodiments.
The epoxy resin composition (E) of the present invention comprises an epoxy compound (A) having two epoxy groups in one molecule, and a phenolic hydroxyl group and/or active ester group (acyloxy group) in one molecule as a functional group. This composition contains two compounds (B) and a phosphonium salt represented by the above general formula (1) as a polymerization catalyst (C), and is polymerized by heating to become a thermoplastic plastic. This composition may contain additives such as organic solvents, fillers, and flame retardants. The fiber-reinforced epoxy resin composition of the present invention contains this epoxy resin composition (E) and reinforcing fiber (F) as essential components.
In this specification, an epoxy compound (A) having two epoxy groups in one molecule may be referred to as an "epoxy compound (A)" or a "bifunctional epoxy compound (A)." A compound (B) having two phenolic hydroxyl groups and/or active ester groups (acyloxy groups) as functional groups in one molecule may be referred to as a "compound (B)" or a "bifunctional compound (B)."

The epoxy compound (A) used in the epoxy resin composition (E) may be any epoxy compound having two epoxy groups in one molecule. The purity of the epoxy compound (A) is preferably 95% or more. If the epoxy compound (A) contains a monofunctional impurity, the molecular weight after polymerization will not increase, so the mechanical properties of the obtained thermoplastic resin product may deteriorate. Therefore, it is preferable that the monofunctional impurity is 2% by weight or less based on the epoxy compound (A). When trifunctional or higher functional impurities are included, a crosslinked structure is likely to be formed starting from the impurities, which increases the dispersion of the polymer and may cause gelation, which may impair thermoplasticity. Therefore, the amount of trifunctional or higher functional impurities is preferably 1% by weight or less based on the epoxy compound (A). As long as the purity of the epoxy compound (A) is high, positional isomers and oligomers may be included. Further, these epoxy compounds (A) may be used alone or in combination.

Examples of the epoxy compound (A) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol Z type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, and bisphenol acetophenone type epoxy resin. resin, bisphenol trimethyl cyclohexane type epoxy resin, bisphenol fluorene type epoxy resin (for example, ZX-1201 (manufactured by Nippon Steel Chemical & Materials Co., Ltd.), etc.), biscresol fluorene type epoxy resin (for example, OGSOL CG-500 (manufactured by Osaka Gas Chemical Co., Ltd.)), ), tetramethylbisphenol A type epoxy resin, tetramethylbisphenol F type epoxy resin (for example, YSLV-80XY (manufactured by Nippon Steel Chemical & Materials Co., Ltd.), etc.), tetra-t-butylbisphenol A type epoxy Resins, bisphenol-type epoxy resins such as tetramethylbisphenol S-type epoxy resin, dihydroxydiphenyl ether-type epoxy resin, thiodiphenol-type epoxy resin, tetrabromobisphenol-A type epoxy resin, biphenol-type epoxy resin, tetramethylbiphenol-type epoxy resin ( For example, biphenol-type epoxy resins such as YX4000 (manufactured by Mitsubishi Chemical Corporation), dimethylbiphenol-type epoxy resin, tetra-t-butylbiphenol-type epoxy resin, hydroquinone-type epoxy resin, methylhydroquinone-type epoxy resin, dibutylhydroquinone-type epoxy resin, etc. Epoxy resins, benzenediol-type epoxy resins such as resorcinol-type epoxy resins, methylresorcin-type epoxy resins, dihydroxyanthracene-type epoxy resins, hydroanthrahydroquinone-type epoxy resins, dihydroxynaphthalene-type epoxy resins, bisnaphtholfluorene-type epoxy resins, diphenyldi Examples include cyclopentadiene type epoxy resin.

Examples of the epoxy compound (A) include bifunctional epoxy compounds obtained by adding hydrogen to the aromatic ring of the above bifunctional epoxy compounds, adipic acid, succinic acid, phthalic acid, tetrahydrophthalic acid, methylhexahydrophthalic acid, and terephthalic acid. , glycidyl ester type epoxy resins manufactured from various dicarboxylic acids such as isophthalic acid, orthophthalic acid, biphenyldicarboxylic acid, and dimer acid and epihalohydrin, and glycidyl amine type epoxy resins manufactured from amine compounds such as aniline and epihalohydrin. Epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, 1,5- Pentanediol diglycidyl ether, polypentamethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polyhexamethylene glycol diglycidyl ether, 1,7-heptanediol diglycidyl ether, polyheptamethylene glycol diglycidyl ether, (Poly)alkylene glycol type epoxy consisting only of a chain structure such as 1,8-octanediol diglycidyl ether, 1,10-decanediol diglycidyl ether, 2,2-dimethyl-1,3-propanediol diglycidyl ether, etc. resins, alkylene glycol type epoxy resins with a cyclic structure such as 1,4-cyclohexanedimethanol diglycidyl ether, aliphatic cyclic epoxy resins, and phosphorus-containing bifunctional epoxy resins (for example, FX-305 (Nippon Steel Chemical & Material Co., Ltd.), diphenylphosphinyl hydroquinone diglycidyl ether, etc.).

In order to improve heat resistance, dihydroxynaphthalene type epoxy resin, bisphenol fluorene type epoxy resin, biscresol fluorene type epoxy resin, bisnaphthol fluorene type epoxy resin are preferable, and bisphenol fluorene type epoxy resin, biscresol fluorene type epoxy resin, A bifunctional epoxy compound having a fluorene ring structure such as a bisnaphtholfluorene type epoxy resin is more preferred. For imparting flame retardancy, a tetrabromobisphenol A type epoxy resin and a phosphorus-containing bifunctional epoxy resin are preferred, and a phosphorus-containing bifunctional epoxy resin is more preferred.

In particular, it is preferable to include an epoxy compound (a) represented by the following general formula (2). In that case, the content in the epoxy compound (A) is preferably 50% by weight or more, more preferably 66% by weight or more, still more preferably 75% by weight or more, particularly preferably 80% by weight or more. The epoxy compound (a) constitutes a part of the epoxy compound (A).

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、エポキシ化合物（ａ）のエポキシ当量は、１５０～３５０ｇ／ｅｑ．が好ましい。エポキシ化合物（ａ）の純度は９５％以上であることが好ましい。

n is the number of repetitions, and its average value is 0 to 5, preferably 0 to 1. Further, the epoxy equivalent of the epoxy compound (a) is 150 to 350 g/eq. is preferred. The purity of the epoxy compound (a) is preferably 95% or more.

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

In formula (2a), 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 group Ren 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 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. can be mentioned. In addition, Ph represents a phenyl group.
Among these, X is a 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, 1,1-fluorene group is preferable, 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 group and 1,1-fluorene group are more preferred. In addition, Ph represents a phenyl group. The alkylene group is meant to include alkylidene groups.

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 the alkyl group 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, t-butyl group, etc. Can be 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 preferable, and methyl group, ethyl group, 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 groups other than hydrogen atoms are preferred. Examples of the alkyl group and aryl group are the same as those exemplified for ^Y1 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 those exemplified for ^Y1 . Preferred Y ³ is a hydrogen atom or the same as Y ¹ .

Examples of the epoxy compound (a) include tetramethylbisphenol F type epoxy resin, tetramethylbiphenol type epoxy resin, biscresol fluorene type epoxy resin, and the like.

The bifunctional compound (B) used in the epoxy resin composition (E) includes a diphenol compound (B1) having two hydroxyl groups bonded to an aromatic ring, and a diester compound having two acyloxy groups bonded to an aromatic ring. (B2) or a monoester compound (B3) having one hydroxyl group and one acyloxy group bonded to an aromatic ring. Note that the diester compound (B2) and the monoester compound (B3) may be referred to as "ester compound" without distinction.
The purity of the bifunctional compound (B) is preferably 95% by weight or more. If a monofunctional impurity is contained, the molecular weight after polymerization will not increase, and the mechanical properties of the produced thermoplastic resin may deteriorate. Therefore, the monofunctional impurity is preferably 2% by weight or less based on the bifunctional compound (B). If trifunctional 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, which may impair thermoplasticity. Therefore, it is preferable that the amount of trifunctional or higher functional impurities is 1% by weight or less based on the bifunctional compound (B). As long as the bifunctional compound (B) has high purity, positional isomers may be included. Further, these bifunctional compounds (B) may be used alone or in combination. The acyloxy group is represented by R-CO-O-, where R is a hydrocarbon group having 1 to 19 carbon atoms. The hydrocarbon group having 1 to 19 carbon atoms is preferably an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms.

The alkyl group having 1 to 12 carbon atoms may be linear, branched, or cyclic, such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, n-pentyl group, isopentyl group, neopentyl group, t-pentyl group, cyclopentyl group, n-hexyl group, isohexyl group, cyclohexyl group, n-heptyl group, cycloheptyl group, methylcyclohexyl group, n- Examples include octyl group, cyclooctyl group, n-nonyl group, 3,3,5-trimethylcyclohexyl group, n-decyl group, cyclodecyl group, n-undecyl group, n-dodecyl group, and cyclododecyl group.
Examples of the aryl group having 6 to 12 carbon atoms include phenyl group, tolyl group, ethylphenyl group, xylyl group, n-propylphenyl group, isopropylphenyl group, mesityl group, naphthyl group, and methylnaphthyl group.
Examples of the aralkyl group having 7 to 13 carbon atoms include benzyl group, methylbenzyl group, dimethylbenzyl group, trimethylbenzyl group, phenethyl group, 2-phenylisopropyl group, and naphthylmethyl group.
Among these, an acyloxy group having a hydrocarbon group having 1 to 7 carbon atoms is preferred, an acetyloxy group, a propanoyloxy group, a butanoyloxy group, a benzoyloxy group, and a methylbenzoyloxy group are more preferred, and an acetyloxy group, A benzoyloxy group is more preferred, and an acetyloxy group is particularly preferred.

Examples of the diphenol compound (B1) include bisphenol A, bisphenol F, bisphenol E, bisphenol Z, bisphenol S, bisphenol AD, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol G, bisphenol M, bisphenol P, Bisphenol PH, bisphenolacetophenone, bisphenol trimethylcyclohexane, bisphenol fluorene, biscresol fluorene, tetramethylbisphenol A, tetramethylbisphenol F, tetra-t-butylbisphenol A, tetramethylbisphenol S, dihydroxydiphenyl ether, dihydroxydiphenylmethane, bis(hydroxyphenoxy) ) Bisphenol compounds such as benzene, thiodiphenol, dihydroxystilbene, biphenol compounds such as biphenol, tetramethylbiphenol, dimethylbiphenol, tetra-t-butylbiphenol, hydroquinone, methylhydroquinone, dibutylhydroquinone, resorcinol, methylresorcinol, etc. Benzenediol compounds, dihydroxyanthracene, dihydroxynaphthalene, dihydroanthrahydroquinone, etc., 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO- HQ), 10-(2,7-dihydroxynaphthyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-NQ), 10-(1,4-dihydroxy-2- naphthyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,5-dihydroxyphenyl)-8-benzyl-9,10-dihydro-9-oxa-10-phosphaphenanthrene- 10-oxide, 10-(2,7-dihydroxy-1-naphthyl)-8-benzyl-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, diphenylphosphinylhydroquinone, diphenylphos Phosphorus-containing materials such as finyl-1,4-dioxynaphthalene, 1,4-cyclooctylenephosphinyl-1,4-phenyldiol, and 1,5-cyclooctylenephosphinyl-1,4-phenyldiol Examples include phenol compounds.
In order to improve the heat resistance of the thermoplastic epoxy resin, dihydroxynaphthalene, bisphenol fluorene, and bis-cresol fluorene are preferred, and bisphenol fluorene and bis-cresol fluorene are more preferred. In particular, when used in the reinforcing fiber-containing epoxy resin composition (E), bisphenol compounds or biphenyl compounds are preferred. Further, a phosphorus-containing phenol compound may be used for the purpose of imparting flame retardancy.

Examples of the diester compound (B2) and the monoester compound (B3) include compounds in which two or one hydroxyl group of the diphenol compound (B1) is substituted with an acyloxy group (active ester). The diester compound (B2) is obtained by acylating the diphenol compound (B1) through a condensation reaction with an acylating agent such as an organic acid anhydride, an organic acid halide, or an organic acid. Monoester compound (B3) is also obtained by adjusting the molar ratio of the acylating agent during acylation of diphenol compound (B1), monoester compound (B3), diester compound (B2), and diphenol. It can be obtained by isolation from a mixture of compound (B1).

Examples of acid components used in the acylation include acetic acid, propionic acid, butyric acid, isobutyric acid, pentanoic acid, octanoic acid, caprylic acid, lauric acid, stearic acid, oleic acid, benzoic acid, t-butylbenzoic acid, Organic acids such as hexahydrobenzoic acid, phenoxyacetic acid, acrylic acid, and methacrylic acid, acid anhydrides of organic acids, halides of organic acids, and esterified products of organic acids can be used.
Examples of organic acid anhydrides include acetic anhydride, benzoic anhydride, phenoxyacetic anhydride, and the like.
Examples of esterified organic acids include methyl acetate, ethyl acetate, butyl acetate, methyl benzoate, and ethyl benzoate. Examples of halides of organic acids include acetic acid chloride, benzoic acid chloride, phenoxyacetic acid chloride, and the like.
These acylating agents include halides of organic acids such as acetic acid chloride, benzoic acid chloride, and phenoxyacetic acid chloride; acid halides and acid anhydrides of organic acids such as acetic anhydride, benzoic anhydride, and phenoxyacetic anhydride; is preferable, and acid anhydrides such as acetic anhydride and benzoic anhydride are more preferable, and acetic anhydride is even more preferable, in the sense that washing with water after esterification is unnecessary and to avoid contamination with halogen, which is disliked in electrical material applications.

In the epoxy resin composition (E), the ratio of compound (B) is 0.90 to 1.10 mol, preferably 0.95 to 0.99 mol, per 1.00 mol of epoxy compound (A). mol, more preferably 0.97 to 0.98 mol.
In the epoxy resin composition (E), the epoxy compound (A) and the compound (B) react sequentially to form a linear structure, thereby exhibiting thermoplasticity. If the epoxy compound (A) is in excess, the reaction will end with an epoxy group, and if the compound (B) is in excess, the reaction will end with a phenol group or an acyloxy group.
If the proportion of compound (B) exceeds 0.99 mol, the reaction ends with the polymer having a phenol group or acyloxy group at its end, which may make it difficult to increase the molecular weight. On the other hand, if the proportion of compound (B) is less than 0.95 mol, the excess epoxy groups may cause a side reaction, resulting in gelation of the polymer and loss of thermoplasticity.

In the epoxy resin composition (E), if the compound (B) is present in the epoxy compound (A) in a crystalline state, the molar ratio will deviate from the design when viewed microscopically. If the reaction is started in this state, polymerization may not proceed sufficiently. In order to allow the polymerization to proceed sufficiently, it is preferable to use an epoxy resin composition (E) in which the compound (B) and the epoxy compound (A) are uniformly compatible with each other.
In addition, it is desirable that the epoxy resin composition (E) is completely dissolved or in a uniform liquid state before adding reinforcing fibers, etc., but for example, in a glass petri dish with a thickness of 2 mm without containing air bubbles. When the haze value in the thickness direction is measured after adding the molten mixture, if the haze value in the thickness direction is less than 30%, it is assumed that the mixture has dissolved or become a uniform liquid to a level that does not affect the polymerization reaction. to decide. The haze value is more preferably less than 20%, still more preferably less than 10%. Note that the method for measuring the haze value follows the conditions described in Examples.

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 the diester compound (B2) include a compound represented by the following formula (3).

Here, X, Y ¹ , Y ² and Y ³ have the same meanings as X, Y ¹ , Y ² and Y ³ in the above formula (2).

The diester compound (B2) may be a phosphorus-containing compound, and examples of the phosphorus-containing compound include a diacetylated cyclic phosphorus-containing compound (DOPO-HQ) represented by the following formula (4). .

When imparting flame retardancy to the epoxy resin composition (E), the phosphorus content is preferably 1% by weight or more and 6% by weight or less, based on the total amount of the epoxy compound (A) and the compound (B), and 1 The content is more preferably .5% by weight or more and 5% by weight or less, and even more preferably 2% by weight or more and 4% by weight. Further, the epoxy resin composition (E) may contain a phosphorus-containing compound (for example, red phosphorus) other than the epoxy compound (A) and the compound (B).

Also, regarding impurity components that do not have active groups that react with either the bifunctional epoxy compound (A) or the bifunctional compound (B) and do not inhibit the polymerization reaction when used alone, the molecular weight after polymerization decreases when the amount increases. There is a fear. Therefore, it is preferable that the amount is 2% by weight or less for both the bifunctional epoxy compound (A) and the bifunctional compound (B).

The epoxy resin composition (E) contains at least one phosphonium salt represented by the following general formula (1) as an essential component as a polymerization catalyst (C). The phosphonium salt acts as a polymerization catalyst for the reaction between the difunctional epoxy compound (A) and the difunctional compound (B).

In formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent an alkyl group, an aryl group or an aralkyl group, and even if they are the same group, they may be different groups. It may be. The alkyl group preferably has 1 to 12 carbon atoms, more preferably 1 to 4 carbon atoms. The aryl group preferably has 6 to 10 carbon atoms, more preferably the phenyl group, and the aralkyl group preferably has 7 to 12 carbon atoms.
Z is an oxygen atom (O) or a sulfur atom (S).

Examples of the polymerization catalyst (C) include tributyl(methyl)phosphonium dimethylphosphate, tributyl(ethyl)phosphonium diethylphosphate, methyltributylphosphonium dimethylphosphate (for example, Hishicolin PX-4MP (manufactured by Nihon Kagaku Kogyo Co., Ltd.)), etc. ), methyltrioctylphosphonium dimethylphosphate, tetrabutylphosphonium o,o-diethylphosphorodithioate (eg, Hishicorin PX-4ET (manufactured by Nihon Kagaku Kogyo Co., Ltd.)), and the like. These phosphonium salts may be used alone or in combination.

The blending amount of the polymerization catalyst (C) is preferably 0.5 to 10 parts by weight based on 100 parts by weight of the epoxy compound (A). Even if the amount of the polymerization catalyst (C) of the present invention is increased, a sufficient pot life can be ensured, and the time required for on-site polymerization can be significantly shortened. If the amount is less than 0.5 part by weight, in-situ polymerization may take time, which may reduce productivity, and there may be a risk of deactivation for some reason before the target molecular weight is reached. On the other hand, if the amount exceeds 10 parts by weight, the polymerization reaction will proceed rapidly, but storage stability may be impaired, causing problems with process suitability, and components that participate in the reaction but are not incorporated into the skeleton. Because of this, there is a risk that the physical properties after polymerization may be impaired, and since it is simply expensive, it is also economically disadvantageous. More preferably 0.5 to 5.0 parts by weight, still more preferably 0.5 to 3.0 parts by weight. It can be selected as appropriate by comprehensively considering the balance between pot life and polymerization time.

Although it is desirable that the epoxy resin composition (E) does not contain an organic solvent, it may contain an organic solvent as a solvent for the polymerization catalyst (C) or for viscosity adjustment, if necessary. The organic solvent is not particularly limited as long as it does not inhibit the reaction between the epoxy compound (A) and the compound (B), but hydrocarbon-based, ketone-based, and ether-based is preferred. Specific examples include toluene, xylene, acetone, methyl ethyl ketone, isobutyl ketone, cyclopentanone, cyclohexanone, diethylene glycol dimethyl ether, and the like. 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 deteriorate. 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 epoxy resin composition desirably has a low viscosity in order to maintain its ability to impregnate reinforcing fibers. The viscosity when heated to 85° C. is preferably 100 Pa·s or less, more preferably 50 Pa·s or less, still more preferably 10 Pa·s or less. Further, the time required for the viscosity to double the initially measured viscosity (viscosity doubling time) is preferably 30 minutes or more, more preferably 60 minutes or more.

The progress of polymerization of the epoxy resin composition (E) is preferably judged by the change in the weight average molecular weight of the polymer. If the weight average molecular weight tends to increase, there is a possibility that the polymerization reaction has not been completed. The polymerization conditions for obtaining a thermoplastic polymer from an epoxy resin composition are preferably, for example, heating conditions at 160°C for 1 hour or less, more preferably 30 minutes or less because it is superior in productivity. preferable.

The progress of polymerization of the reinforcing fiber-containing epoxy resin composition can also be determined by the change in the weight average molecular weight of the polymer. The polymerization conditions for obtaining a fiber-reinforced thermoplastic polymer from a reinforcing fiber-containing epoxy resin composition are, for example, preferably heating at 160°C for 4 hours or less, more preferably 2 hours or less. It is more preferable because it has excellent properties.

The weight average molecular weight (Mw) of the polymer obtained by polymerizing the epoxy resin composition (E) is 30,000 or more and 200,000 or less. If the weight average molecular weight of the polymer is less than the lower limit of the range, it will contain a large amount of compounds whose polymerization has not progressed sufficiently, and there is a possibility that the mechanical strength will deteriorate. On the other hand, when the weight average molecular weight of the polymer exceeds the upper limit of the range, the crosslinking reaction is progressing, and thermoplasticity may be impaired. Preferably, Mw is 30,000 or more and 150,000 or less, more preferably 50,000 or more and 100,000 or less. The epoxy equivalent of the polymer is 10,000 g/eq. The above is desirable. Epoxy equivalent is 10,000g/eq. If it is less than that, polymerization may not proceed sufficiently. The epoxy equivalent is preferably 20,000 g/eq. Above, more preferably 25,000g/eq. That's all. The glass transition temperature (Tg) of the polymer is preferably 120°C or higher, more preferably 130°C or higher, even more preferably 140°C or higher.

The epoxy resin composition (E) 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 that additives different from those in the resin phase be blended, but a plasticizer and a compatible flame retardant may be included as long as they do not affect the reaction.

The epoxy resin composition (E) becomes a thermoplastic plastic by polymerizing. 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 can be obtained by mixing or impregnating the above-mentioned epoxy resin composition with reinforcing fibers. Moreover, prepreg can be obtained as follows.

An epoxy resin composition film can be obtained by coating the epoxy resin composition (E) on a paper or plastic film that has been subjected to a release treatment, and if necessary, applying a cover film that has been treated with a release treatment. can. As for the release paper, release plastic film, and cover film, known ones can be used and there are no particular limitations. The thickness of the epoxy resin composition film is determined by the design thickness of the prepreg and the resin ratio, but the usual thickness is 1 μm or more and 300 μm or less. If it is less than 1 μm, there is a problem that the opening of the fibers becomes noticeable unless the reinforcing fibers are defibrated properly, and if it exceeds 300 μm, it becomes difficult to uniformly impregnate the reinforcing fibers. Preferably it is 5 μm or more and 150 μm or less, more preferably 10 μm or more and 100 μm or less.

The reinforcing fiber (F) used in the present invention is for reinforcing plastics such as carbon fiber, aramid fiber, and cellulose fiber, and is not particularly limited. Furthermore, the form of the fibers is not particularly limited, and examples include UD sheets with aligned fibers, woven fabrics, tows, chopped fibers, nonwoven fabrics, and papermaking. However, from the viewpoint of impregnation, the thickness of each fiber bundle is 1 mm or less, preferably 0.5 mm or less, and 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-mentioned epoxy resin composition and/or epoxy resin composition film and reinforcing fibers. The weight ratio of the reinforcing fibers to the epoxy resin composition is preferably 5:5 to 8:2. In terms of resin content (Rc), it is 20 to 50% by weight, and it is possible to increase the proportion of reinforcing fibers, and if necessary, Rc can be reduced to 35% by weight or less. If the ratio of reinforcing fibers is too small, the strength required of the fiber-reinforced material may not be fully satisfied, and if the ratio of reinforcing fibers is too large, defects such as voids may occur.

EXAMPLES Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the following Examples. Unless otherwise specified, "parts" represent parts by weight, and "%" represent weight %.

The raw materials, polymerization catalysts, solvents, and reinforcing fibers used in the examples are as follows.

[Epoxy compound]
A1: Tetramethylbiphenol type epoxy resin (manufactured by Mitsubishi Chemical Corporation, YX4000, epoxy equivalent: 186 g/eq.)
A2: Bisphenol fluorene type epoxy resin (Nippon Steel Chemical & Materials Co., Ltd., ESF-300, epoxy equivalent 250g/eq.)

Ｂ３：１０－（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、下記構造式、水酸基当量１６２ｇ／ｅｑ．）

Ｂ４：合成例１で得られたジエステル系化合物（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）で表されるリン含有化合物、リン含有率７．６％、アセチル基当量２０４ｇ／ｅｑ．）

[Phenol compounds, ester compounds]
B1: Bisphenol A (manufactured by Nippon Steel Chemical & Materials Co., Ltd., hydroxyl equivalent: 114 g/eq.)
B2: 4,4'-bis(3,3,5-trimethylcyclohexylidene) bisphenol (manufactured by Honshu Chemical Industry Co., Ltd., BisP-HTG, hydroxyl equivalent weight 155 g/eq.)

B3: 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Co., Ltd., HCA-HQ, the following structural formula, hydroxyl group equivalent: 162 g/ eq.)

B4: Diester compound obtained in Synthesis Example 1 (10-(2,5-diacetoxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, with formula (4) Phosphorus-containing compound represented, phosphorus content 7.6%, acetyl group equivalent 204g/eq.)

Ｃ２：テトラブチルホスホニウム・ｏ，ｏ－ジエチルホスホロジチオエート（日本化学工業株式会社製、ヒシコーリン ＰＸ－４ＥＴ）

Ｃ３：２，３－ジヒドロ－１Ｈ－ピロロ－［１，２－ａ］ベンズイミダゾール（四国化成工業株式会社製、キュアゾール ＴＢＺ）

[Polymerization catalyst]
C1: Methyltributylphosphonium dimethylphosphate (Hishicorin PX-4MP, manufactured by Nihon Kagaku Kogyo Co., Ltd.)

C2: Tetrabutylphosphonium o,o-diethylphosphorodithioate (Nihon Kagaku Kogyo Co., Ltd., Hishicorin PX-4ET)

C3: 2,3-dihydro-1H-pyrrolo-[1,2-a]benzimidazole (Curezol TBZ, manufactured by Shikoku Kasei Kogyo Co., Ltd.)

[others]
D: Cyclohexanone (first class reagent, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.)
E: PAN-based carbon fiber (manufactured by Toray Industries, Inc., trading card T700-12K-60E)

The evaluation method in Examples is as follows.
(1) Compatibility:
Whether the phenol compound was uniformly melted in the epoxy compound was determined by the haze value. Specifically, the epoxy resin composition was placed in a colorless and transparent glass petri dish to a thickness of 2 mm, and the haze value was adjusted to "less than 5% (<5)" using a haze standard plate manufactured by Murakami Color Research Institute as a reference. ” “5% or more and less than 10% (<10)” “10% or more and less than 20% (<20)” “20% or more and less than 30% (<30)” “30% or more (30<)” evaluated. If the haze value is less than 30%, it can be determined that the phenol compound is uniformly dissolved in the epoxy compound.

(2) Viscosity and viscosity doubling time:
The viscosity and viscosity doubling time at 85°C were measured in accordance with the JIS K6870 standard and the JIS K5600-2-3 standard. Specifically, it was measured using MCR 102 (manufactured by Anton Paar). The viscosity was measured when heated to 85° C. under the conditions of a measurement frequency of 3 Hz, a load strain of 1%, a 20 mm diameter flat plate, and a gap between the plates of 0.5 mm. Further, when the sample was kept at 85° C., the time required for the viscosity to double from the initially measured viscosity was measured, and this was defined as the viscosity doubling time. If the viscosity is less than twice the initial viscosity even after being kept warm for 60 minutes or more, it can be determined that there is sufficient potential, so the measurement time was limited to 60 minutes, and in that case, it was written as "60<".

(3) Molecular weight:
The weight average molecular weight (Mw) and number average molecular weight (Mn) were determined by GPC measurement. Specifically, we used a main body HLC8320GPC (manufactured by Tosoh Corporation) equipped with a column (TSKgel SuperH-H, SuperH2000, SuperHM-H, SuperHM-H, manufactured by Tosoh Corporation) in series, and the column temperature was The temperature was set to 40°C. In addition, tetrahydrofuran (THF) was used as the eluent at a flow rate of 1.0 mL/min, and a differential refractive index detector was used as the detector. The measurement sample used was one in which 0.1 g of solid content was dissolved in 10 mL of THF and filtered through a 0.45 μm microfilter, and the injection amount was 50 μL. Mw and Mn were calculated using a calibration curve obtained from standard polystyrene (manufactured by Tosoh Corporation, PStQuick A, PStQuick B, PStQuick C). Note that GPC8020 Model II version 6.00 manufactured by Tosoh Corporation was used for data processing.

(4) Glass transition temperature (Tg):
In accordance with the JIS K7121 standard, DSC Tmg (glass state and rubber state) was measured using a differential scanning calorimeter (EXSTAR6000 DSC6200, manufactured by Hitachi High-Tech Science Co., Ltd.) at a temperature increase of 10°C/min. The temperature is expressed as the midpoint temperature of the mutation curve with respect to the tangent line.

(5) Solvent solubility:
1 g of sample and 50 mL of tetrahydrofuran were added to a 100 mL vial, subjected to ultrasonic diffusion at room temperature for 1 hour, and then allowed to stand at room temperature for 23 hours or more to dissolve. When the polymer was dissolved in the solvent and no solid matter was observed, the solvent solubility was evaluated as ○. When a portion remained undissolved and was observed as a gel state, it was marked as △. When the polymer did not dissolve in the solvent, it was marked as ×.

(6) Bending strength and bending modulus:
Measurement was performed in a 90 degree direction using a three-point bending test (method A) according to the JIS K7074 standard. A testing machine (Autograph AGS-X manufactured by Shimadzu Science) was used, the sample dimensions were 2 mm in thickness, 100 mm in length, and 15 mm in width, the bending span was 70 mm, and the test was conducted at a test speed of 1 mm/min. .

Synthesis example 1 (ester compound)
162 parts of bifunctional phenol compound B3, 105 parts of acetic anhydride, and 79 parts of pyridine were charged at room temperature into a glass reaction vessel equipped with a stirring device, a thermometer, a nitrogen gas introduction device, a cooling tube, and a dropping device. The temperature was raised to 60° C. while stirring while flowing nitrogen gas, and the reaction was carried out for 2 hours. Thereafter, vacuum drying was performed for 2 hours at 150° C. and 1.3 kPa (10 torr) to obtain 203 parts of phosphorus-containing compound B4 represented by the above formula (4).

Synthesis example 2 (precursor mixture)
722 parts of A1, 971 parts of A2, 500 parts of B1, and 500 parts of B2 were each weighed and ground and mixed using a Henschel mixer. Subsequently, melt mixing was performed using an S1KRC kneader (manufactured by Kurimoto Iron Works Co., Ltd.) whose barrel temperature was preheated to 190°C, the entire amount was collected in a metal can, and cooled to 85°C while stirring to form an epoxy resin composition. A precursor mixture (F1) was obtained.

Synthesis example 3 (precursor mixture)
A precursor mixture (F2) of an epoxy resin composition was obtained by carrying out the same operation as in Synthesis Example 2, except that A1 was changed to 1356 parts, A2 was changed to 0 parts, B1 was changed to 300 parts, and B2 was changed to 700 parts.

Synthesis example 4 (precursor mixture)
A precursor mixture (F3) of an epoxy resin composition was obtained by performing the same operation as in Synthesis Example 2, except that A1 was changed to 1136 parts, A2 was changed to 0 parts, B1 was changed to 280 parts, and B4 was changed to 720 parts. The phosphorus content of the precursor mixture (F3) was 2.6%.

The formulations (parts by weight) of Synthesis Examples 2 to 4 are summarized in Table 1.

Example 1 (epoxy resin composition)
One part of C1 (polymerization catalyst) was heated to 50° C. in advance to bring it into a molten state. 100 parts of the precursor mixture (F1) was placed in a planetary mixer set at 85°C, and the above polymerization catalyst was added and mixed. After mixing, the mixture was quickly taken out and immediately cooled to 40° C. or lower to obtain an epoxy resin composition (G1).

When the haze value (compatibility) of the epoxy resin composition (G1) was measured, it was 5% or more and less than 10% (<10), and it was determined that it was uniformly dissolved. When the viscosity at 85° C. was measured, it was 5.5 Pa·s, and the viscosity doubling time was 60 minutes or more.

The obtained epoxy resin composition (G1) was heated and stirred at 85°C, poured into a steel chrome-plated mold container with a clearance of 4 mm, and thermally polymerized at 160°C for 60 minutes in a hot air circulation oven. A polymer (H1), which is a thermoplastic resin, was obtained. The obtained polymer had Mw of 61,000, Mn of 12,000, glass transition temperature of 148° C., and solvent solubility of 0.

Examples 2 to 5, Comparative Examples 1 to 3 (epoxy resin composition)
Epoxy resin compositions (G2 to G8) and polymers (H2 to H8) were obtained by blending the formulations in the amounts (parts) shown in Table 2 and in the same manner as in Example 1. The same measurements as in Example 1 were performed, and the evaluation results are shown in Table 1. In addition, in the table, those having a value for D (organic solvent) were used in a state in which the polymerization catalyst was dissolved in the organic solvent in advance. The obtained epoxy resin compositions and polymers (G2 to G8, H2 to H8) were measured in the same manner as in Example 1, and the results are shown in Table 2.

Example 6
A release paper that had been subjected to release treatment was fixed on a hot plate preheated to 85°C with the release side facing upward, and the epoxy resin composition (G1) obtained in Example 1 was placed on the release paper. After mounting, coating was performed using a bar coater preheated to 85° C. so that the area weight of the resin was 79 g/m ² . Immediately after coating, it was removed from the hot plate and cooled in the air to obtain an epoxy resin composition sheet.
Subsequently, carbon fibers (E) were bonded onto the obtained epoxy resin composition sheet so that the area weight of the fibers was 153 g/ ^m2 , and a surface pressure of 0 was applied using a hot press preheated to 90°C. A pressure of .5 MPa was applied, and after 1 minute, it was taken out and air-cooled to obtain a prepreg (I1) with Rc=34%.

After 13 sheets of prepreg (I1) were laminated with the fibers oriented in the same direction, release films were attached to the top and bottom surfaces and sandwiched between 3 mm thick aluminum plates. After wrapping the coupler and the aluminum plate sandwiching the prepreg in bag film, the coupler and vacuum pump were connected to evacuate the air inside the bag film. The bug was placed in a hot air circulation oven preheated to 160° C. and cured while maintaining vacuum to form a unidirectional fiber-reinforced plastic (J1) with a thickness of 2 mm. Note that the curing temperature was 160° C. and the curing time was 120 minutes.

As a result of measuring the molecular weight of the resin component of the obtained unidirectionally reinforced fiber plastic (J1), the Mw was 67,000 and the Mn was 10,000. The glass transition temperature (Tg) of the unidirectionally reinforced fiber plastic was measured to be 148°C. The bending strength and bending elastic modulus were measured and found to be 78 MPa and 7.2 GPa.

Examples 7 to 12, Comparative Examples 4 to 6
Unidirectional fiber-reinforced plastics (J2 to J8) were obtained by molding according to the same procedure as in Example 6 and under the conditions shown in Table 3. The same evaluation as in Example 6 was performed. The results are shown in Table 3.

By using the epoxy resin composition of the present invention as a base material resin of fiber reinforced plastic (FRP), thermoplastic CFRP with high heat resistance, sufficiently long pot life, and excellent polymerizability can be obtained. be able to.

The epoxy resin composition of the present invention is useful as a base material resin for fiber-reinforced plastics (FRP), and is particularly suitable for in-situ polymerization type thermoplastic epoxy resin applications.

Claims (11)

An epoxy resin composition used as a base material resin for reinforced fiber plastics, comprising an epoxy compound (A) having two epoxy groups in one molecule, and a phenolic hydroxyl group and/or active ester group in one molecule as a functional group. An epoxy resin composition characterized by containing a compound (B) having two compounds, and a phosphonium salt represented by the following general formula (1) as a polymerization catalyst (C).

(In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represent an alkyl group, an aryl group, or an aralkyl group, and even if they are the same group, they may be different groups. (Z may represent an oxygen atom or a sulfur atom.) It does not contain an organic solvent, or if it contains an organic solvent, the content of the organic solvent is 0.05% by weight or more and 10% by weight or less in the epoxy resin composition, and the epoxy resin composition is heated to 85 ° C. The epoxy resin composition according to claim 1, which has a viscosity of 100 Pa·s or less. The epoxy resin composition according to claim 1, wherein the compounding amount of the epoxy compound (A) and the compound (B) is 0.95 to 1.05 mol of the compound (B) per 1 mol of the epoxy compound (A). . The epoxy resin composition according to claim 1, wherein the polymerization catalyst (C) is used in an amount of 0.5 to 10 parts by weight per 100 parts by weight of the epoxy compound (A). The epoxy resin composition according to claim 1, wherein a part or all of the epoxy compound (A) and/or the compound (B) is a phosphorus-containing compound. The epoxy resin composition according to claim 5, having a phosphorus content of 1 to 6% by weight. A reinforcing fiber-containing epoxy resin composition comprising the epoxy resin composition according to any one of claims 1 to 6 and reinforcing fibers. The reinforcing fiber-containing epoxy resin composition according to claim 7, which contains carbon fibers as reinforcing fibers in a proportion of 50 to 80% by weight. A prepreg comprising the reinforcing fiber-containing epoxy resin composition according to claim 7. A fiber-reinforced plastic using the reinforcing fiber-containing epoxy resin composition according to claim 7. A fiber reinforced plastic using the prepreg according to claim 9.