WO2023167049A1 - Epoxy resin composition, reinforcing fiber-containing epoxy resin composition, prepreg, fiber reinforced plastic employing same, and thermoplastic epoxy resin - Google Patents

Abstract

The present invention addresses the problem of providing an epoxy resin composition that contains a bifunctional epoxy resin, a bifunctional compound, and a polymerization catalyst, that has sufficiently long pre-reaction working life, that is capable of sufficiently promoting a polymerization reaction, and that is converted to a thermoplastic epoxy resin as a result of said reaction. The present invention also addresses the problem of providing a reinforcing fiber-containing epoxy resin composition and a prepreg that contain said epoxy resin composition and a fiber reinforced plastic employing said materials.　The present invention provides an epoxy resin composition that contains a bifunctional epoxy compound, a bifunctional compound, and a polymerization catalyst as essential components and that is converted to a thermoplastic epoxy resin by a polymerization reaction, wherein the polymerization catalyst is an N-substituted aminopyridine compound represented by formula (1). In the formula, each of R1 and R2 independently represents a hydrocarbon group having 1-12 carbon atoms, additionally, R1 and R2 may form a heterocycle bonding with each other, and an atomic bonding thereof may include -O-, -NH-, or -NR4-. R4 is a hydrocarbon group having 1-12 carbon atoms. R3 is independently a hydrocarbon group having 1-12 carbon atoms, and k is an integer of 0-4.

Description

Epoxy resin composition, reinforcing fiber-containing epoxy resin composition, prepreg and fiber-reinforced plastic using these, and thermoplastic epoxy resin

The present invention relates to epoxy resin compositions, reinforcing fiber-containing epoxy resin compositions, prepregs, and fiber-reinforced plastics and thermoplastic epoxy resins 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 the improvement of 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. This makes it difficult to apply the resin film or impregnate the fibers, and the reactivity in the fibers also decreases.

Adding a solvent or raising the handling temperature of the resin can be mentioned as a method of making the viscosity of the resin with a rigid skeleton molecular structure low and facilitating the process of coating the resin film and impregnating the resin. Addition of a solvent deteriorates physical properties of the final product by remaining in the polymer. An increase in handling temperature increases the reaction rate of the resin, shortening the pot life and making handling difficult.

By reducing the amount of polymerization catalyst added, it is possible to extend the pot life of the resin. may be deactivated due to side reactions or the like before reaching the molecular weight of .

Examples of Patent Document 3 use a phosphine-based polymerization catalyst and show an in-situ polymerization type thermoplastic epoxy resin whose Tg is raised to 139°C. If the solvent remains in the polymer, there is concern that it may adversely affect physical properties. In Patent Document 4, an amine-based catalyst is studied as a polymerization catalyst, but there is no description regarding the pot life.

JP 2006-321897 A WO2004/060981 WO2006/123577 WO2010/079832

An object 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 that has a sufficiently long working time and allows a polymerization reaction to proceed sufficiently, a reinforcing fiber-containing epoxy resin composition containing the same, a prepreg, and a fiber-reinforced plastic using these.

The inventors of the present invention have made intensive studies to solve the above problems, and 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 and heat-treated. The inventors have found that the above problems can be solved by using a specific N-substituted aminopyridine compound as a polymerization catalyst in obtaining a plastic epoxy resin, and have completed the invention.

That is, the present invention provides an epoxy compound (A) having two epoxy groups in one molecule and a compound (B) having two phenolic hydroxyl groups and/or active ester groups (acyloxy groups) as functional groups in one molecule. and an epoxy resin composition containing a polymerization catalyst (C) as an essential component and becoming a thermoplastic epoxy resin by a polymerization reaction, wherein the polymerization catalyst (C) is an N-substituted aminopyridine represented by the following formula (1): It is a system compound.

In the formula, R1 and R2 are independently a hydrocarbon group having 1 to 12 carbon atoms, and R1 and R>2 may be combined to form a heterocyclic ring, and , -NH-, or -NR4-. However, R4 is a hydrocarbon group having 1 to 12 carbon atoms. R3 is independently a hydrocarbon group having 1-12 carbon atoms and k is an integer of 0-4.

It is preferable to blend 0.90 to 1.10 mol of the compound (B) with respect to 1 mol of the epoxy compound (A), and the amount of the polymerization catalyst (C) used is the epoxy compound (A) and the compound ( It is preferably 0.01 to 10 parts by weight per 100 parts by weight of B).

Polymerization catalyst (C) from 4-(dimethylamino)pyridine, 4-pyrrolidinopyridine, 4-piperidinopyridine, 4-(4-methylpiperidino)pyridine, 4-morpholinopyridine, and 4-piperazinopyridine is preferably selected from the group consisting of

Part or all of the epoxy compound (A) and/or compound (B) may be a phosphorus-containing compound, in which case the phosphorus content of the resulting thermoplastic epoxy resin should be 1 to 6% by weight. is preferred.

The epoxy equivalent of the obtained thermoplastic epoxy resin is 4,000 to 200,000 g/eq. is preferably

The epoxy resin composition does not contain an organic solvent, or when it contains an organic solvent, the content of the organic solvent is 0.01% by weight or more and 10% by weight or less of the epoxy resin composition, and heated to 85 ° C. It is preferable that the epoxy resin composition has a viscosity of 100 Pa·s or less when measured.

The present invention also provides a reinforcing fiber-containing epoxy resin composition characterized by containing the above epoxy resin composition and reinforcing fibers, and a prepreg made of the above reinforcing fiber-containing epoxy resin composition. The reinforcing fibers are preferably carbon fibers and preferably contained in a proportion of 50 to 80% by weight.

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

The present invention also provides a thermoplastic epoxy resin obtained from the above epoxy resin composition, which has a weight average molecular weight of 30,000 or more and 200,000 or less, and an impact strength of 12 kJ/ It is a thermoplastic epoxy resin with m ² or more.

The epoxy resin composition of the present invention can reduce the amount of catalyst added, and can exhibit good reactivity while maintaining a relatively long pot life. Therefore, it is useful as an in-situ polymerizable resin composition, and can provide a thermoplastic fiber reinforced plastic (FRP) having a low void content and 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 has an epoxy compound (A) having two epoxy groups in one molecule and two phenolic hydroxyl groups and/or active ester groups (acyloxy groups) in one molecule as functional groups. The composition contains the compound (B) and the N-substituted aminopyridine compound represented by the above formula (1) as essential components as a polymerization catalyst (C), and is polymerized by heating to form a thermoplastic epoxy resin. The composition may contain additives such as organic solvents, fillers and flame retardants.
In this specification, an epoxy compound (A) having two epoxy groups in one molecule may be referred to as "epoxy compound (A)" or "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 is sometimes referred to as "compound (B)" or "bifunctional compound (B)". Thermoplastic epoxy resins are sometimes referred to as "thermoplastic resins".

The epoxy compound (A) used in the epoxy resin composition of the present invention may be an 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 monofunctional impurities, the molecular weight after polymerization will 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 relative to the epoxy compound (A). 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 more functional impurities are preferably 1% by weight or less relative to the epoxy compound (A). If the purity as the epoxy compound (A) is high, positional isomers and oligomers may be included. Moreover, these epoxy compounds (A) may be used alone or in combination of two or more.

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, bisphenol acetophenone type epoxy resin. Resin, bisphenol trimethylcyclohexane 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 (Osaka Gas Chemical Co., Ltd.), tetramethylbisphenol A type epoxy resin, tetramethylbisphenol F type epoxy resin (e.g., YSLV-80XY (manufactured by Nippon Steel Chemical & Materials Co., Ltd.), etc.), tetra-t-butylbisphenol A type epoxy Resin, bisphenol type epoxy resin 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, YX-4000 (manufactured by Mitsubishi Chemical Corporation), etc.), dimethylbiphenol type epoxy resin, biphenol type epoxy resin such as tetra-t-butylbiphenol type epoxy resin, hydroquinone type epoxy resin, methylhydroquinone type epoxy resin, dibutyl Hydroquinone type epoxy resin, resorcinol type epoxy resin, benzenediol type epoxy resin such as methylresorcin type epoxy resin, dihydroxyanthracene type epoxy resin, hydroanthrahydroquinone type epoxy resin, dihydroxynaphthalene type epoxy resin, bisnaphtholfluorene type epoxy resin, A diphenyldicyclopentadiene type epoxy resin and the like are included.

The bifunctional epoxy compound (A) further includes a bifunctional epoxy compound obtained by adding hydrogen to the aromatic ring of the bifunctional epoxy compound, adipic acid, succinic acid, phthalic acid, tetrahydrophthalic acid, methylhexahydrophthalic acid, Glycidyl ester type epoxy resins produced from various dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, biphenyldicarboxylic acid, dimer acid, and epihalohydrin, and glycidyl produced from an amine compound such as aniline and epihalohydrin Amine type 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 (Poly)alkylene glycol consisting only of a chain structure such as ether, 1,8-octanediol diglycidyl ether, 1,10-decanediol diglycidyl ether, 2,2-dimethyl-1,3-propanediol diglycidyl ether type epoxy resins, alkylene glycol type epoxy resins having 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.), diphenylphosphinylhydroquinone diglycidyl ether, etc.).

In order to improve the heat resistance of thermoplastic epoxy resins, dihydroxynaphthalene-type epoxy resins, bisphenolfluorene-type epoxy resins, bis-cresol-fluorene-type epoxy resins, and bis-naphthol-fluorene-type epoxy resins are preferable. Bifunctional epoxy compounds having a fluorene ring structure, such as fluorene type epoxy resins and bisnaphtholfluorene type epoxy resins, are more preferred. Tetrabromobisphenol A-type epoxy resins and phosphorus-containing bifunctional epoxy resins are preferred for imparting flame retardancy, and phosphorus-containing bifunctional epoxy resins are more preferred.

In particular, when used in a reinforcing fiber-containing epoxy resin composition, it preferably contains an epoxy compound (a) represented by the following 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, and particularly preferably 80% by weight or more. Epoxy compound (a) constitutes a part of epoxy compound (A).

n is the number of repetitions, and its average value is 0-5, preferably 0-1. Moreover, 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 higher.

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 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, 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 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 group and 1,1-fluorene group are more preferred. In addition, Ph represents a phenyl group. An alkylene group is meant to include an alkylidene group.

Y1 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, naphthyl group and the like.
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.

Y2 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 aryl group are the same as those exemplified for Y1 above. Preferred Y2 is the same as Y1.
Y3 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 Y3 is a hydrogen atom or the same as Y1.

Examples of the epoxy compound (a) include tetramethylbisphenol F-type epoxy resin, tetramethylbiphenol-type epoxy resin, bisphenolfluorene-type epoxy resin, biscresolfluorene-type epoxy resin, and the like.

The bifunctional compound (B) used in the epoxy resin composition of the present invention 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. The diester compound (B2) and the monoester compound (B3) are sometimes referred to as "ester compounds" without distinction.
The purity of the bifunctional compound (B) is preferably 95% by weight or more. 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 relative to the bifunctional compound (B). 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 relative to the bifunctional compound (B). If the purity of the bifunctional compound (B) is high, positional isomers may be contained. Moreover, these bifunctional compounds (B) may be used alone or in combination of two or more. 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, and examples thereof include 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- octyl group, cyclooctyl group, n-nonyl group, 3,3,5-trimethylcyclohexyl group, n-decyl group, cyclodecyl group, n-undecyl group, n-dodecyl group, cyclododecyl group and the like.
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, methylnaphthyl group and the like.
The aralkyl group having 7 to 13 carbon atoms includes, for example, benzyl group, methylbenzyl group, dimethylbenzyl group, trimethylbenzyl group, phenethyl group, 2-phenylisopropyl group, naphthylmethyl group and the like.
Among these, an acyloxy group having a hydrocarbon group having 1 to 7 carbon atoms is preferable, and an acetyloxy group, a propanoyloxy group, a butanoyloxy group, a benzoyloxy group and a methylbenzoyloxy group are more preferable, 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, bisphenoltrimethylcyclohexane, bisphenolfluorene, biscresolfluorene, tetramethylbisphenol A, tetramethylbisphenol F, tetra-t-butylbisphenol A, tetramethylbisphenol S, dihydroxydiphenyl ether, dihydroxydiphenylmethane, bis(hydroxyphenoxy ) Biphenol compounds such as benzene, thiodiphenol, and dihydroxystilbene; biphenol compounds such as biphenol, tetramethylbiphenol, dimethylbiphenol, and tetra-t-butylbiphenol; 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, diphenylphosph Phosphorus-containing compounds such as finyl-1,4-dioxynaphthalene, 1,4-cyclooctylenephosphinyl-1,4-phenyldiol, and 1,5-cyclooctylenephosphinyl-1,4-phenyldiol A phenol compound etc. are mentioned.
Dihydroxynaphthalene, bisphenol fluorene, and bis-cresol fluorene are preferred, and bisphenol fluorene and bis-cresol fluorene are more preferred for improving the heat resistance of thermoplastic epoxy resins. A bisphenol compound or a biphenyl compound is particularly preferred when used in a reinforcing fiber-containing epoxy resin composition. A phosphorus-containing phenol compound may also be used for the purpose of imparting flame retardancy.

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

Acid components used for the above acylation include, for example, 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, esters of organic acids, and the like can be used.
Acid anhydrides of organic acids include, for example, acetic anhydride, benzoic anhydride, and phenoxyacetic anhydride.
Examples of esterified organic acids include methyl acetate, ethyl acetate, butyl acetate, methyl benzoate, and ethyl benzoate. Halides of organic acids include, for example, acetic acid chloride, benzoic acid chloride, phenoxyacetic acid chloride and the like.
Examples of these acylating agents include halides of organic acids such as acetic acid chloride, benzoic acid chloride and phenoxyacetic acid chloride; acid halides such as acetic anhydride, benzoic acid anhydride and phenoxyacetic acid anhydride; and acid anhydrides of organic acids. 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 contamination of halogen, which is disliked in electronic materials, is avoided.

In the epoxy resin composition of the present invention, the ratio of compound (B) is 0.90 to 1.10 mol, preferably 0.95 to 0.99, per 1.00 mol of epoxy compound (A). mol, more preferably 0.97 to 0.98 mol.
In the epoxy resin composition of the present invention, the epoxy compound (A) and the compound (B) react successively to form a straight chain structure, thereby exhibiting thermoplasticity. When the epoxy compound (A) is in excess, it becomes an epoxy group terminal, and when the compound (B) is excessive, it becomes a phenol group terminal or an acyloxy group terminal, and the reaction is completed.
If the proportion of the compound (B) exceeds 0.99 mol, the polymer will end up with a phenol group terminal or an acyloxy group terminal, and the reaction will end, which may make it difficult to increase the molecular weight. On the other hand, if the proportion of the compound (B) is less than 0.95 mol, excess epoxy groups may cause a side reaction, resulting in gelation of the polymer and loss of thermoplasticity.

In the epoxy resin composition of the present invention, if the compound (B) is present in the epoxy compound (A) 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. In order to allow the polymerization to proceed sufficiently, an epoxy resin composition in which the compound (B) and the epoxy compound (A) are uniformly compatible with each other is preferred.
In addition, it is desirable that the epoxy resin composition is completely dissolved or in a uniform liquid state before the reinforcing fibers are 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 method for measuring the haze value follows the conditions described in Examples.

Examples of the diester compound (B2) include compounds represented by the following formula (3).

Here, X, Y1, Y2 and Y3 are synonymous with X, Y1, Y2 and Y3 in formula (2a) above.

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

From the viewpoint of imparting flame retardancy, the phosphorus content is preferably 1% by weight or more and 6% by weight or less, and 1.5% by weight or more and 5% by weight or less, based on the total amount of the epoxy compound (A) and the compound (B). is more preferable, and 2% by weight or more and 4% by weight is even more preferable.

In addition, even for impurity components that do not have an active group that reacts with either the epoxy compound (A) or the compound (B) and that do not inhibit the polymerization reaction by themselves, there is a risk that the molecular weight after polymerization will decrease if the amount increases. Therefore, the content of impurities is preferably 2% by weight or less with respect to both the bifunctional epoxy compound (A) and the bifunctional compound (B).

The epoxy resin composition of the present invention contains, as a polymerization catalyst (C), at least one N-substituted aminopyridine compound represented by the following formula (1) as an essential component. The N-substituted aminopyridine compound acts as a catalyst for the reaction between the bifunctional epoxy compound (A) and the bifunctional compound (B).

In formula (1), R1 and R2 are independently a hydrocarbon group having 1 to 12 carbon atoms, and R1 and R2 may be bonded to each other to form a heterocyclic ring. -, -NH-, or -NR4- may be present. However, R4 is a hydrocarbon group having 1 to 12 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms.
R1 and R2 are preferably alkyl groups having 1 to 3 carbon atoms, or groups having a cyclopentane ring or cyclohexane ring formed by mutual bonding.

R3 is independently a hydrocarbon group having 1 to 12 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms.
The hydrocarbon group having 1 to 12 carbon atoms is the same as the non-bonded case exemplified for R1 and R2.
k represents the number of substituents R3 and is an integer of 0 to 4, preferably 0 or 1, more preferably 0.

The substitution position of the N-substituted amino group may be the 2-, 3- or 4-position of pyridine, preferably the 4-position, and more preferably the compound represented by the following formula (5).

In formula, R1 and R2 are synonymous with R1 and R2 of formula (1).

Examples of the polymerization catalyst (C) include 2-dimethylaminopyridine, 2-pyrrolidinopyridine, 2-(dimethylamino)-6-methylpyridine, 2-methylethylaminopyridine, 2-methylbutylaminopyridine, 2- diethylaminopyridine, 2-methylpropylaminopyridine, 2-pyrrolidino-4-methylpyridine, 2-pyrrolidino-5-methylpyridine, 2-pyrrolidino-6-methylpyridine, 2-morpholinopyridine, 3-dimethylaminopyridine, N, N-diethyl-3-pyridinamine, 4-dimethylaminopyridine, 4-diethylaminopyridine, 4-dipropylaminopyridine, 4-dibutylaminopyridine, 4-dibenzylaminopyridine, 4-dihexylaminopyridine, 4-dihexylamino pyridine, 4-dioctylaminopyridine, 4-dinonylaminopyridine, 4-didecylaminopyridine, 4-undecylaminopyridine, 4-dodecylaminopyridine, 4-dibenzylaminopyridine, 4-diphenylaminopyridine, 4- pyrrolidinopyridine, 4-piperidinopyridine, 4-(4-methylpiperidino)pyridine, 4-morpholinopyridine, 4-methylethylaminopyridine, 4-methylpropylaminopyridine, 4-methylbenzylaminopyridine, 4-methylphenyl Aminopyridine, 2-methyl-4-(dimethylamino)pyridine, 2-ethyl-4-(dimethylamino)pyridine, 2-phenyl-4-(dimethylamino)pyridine, 3-methyl-4-(dimethylamino)pyridine , 3-ethyl-4-(dimethylamino)pyridine, 3-phenyl-4-(dimethylamino)pyridine, 3,5-dimethyl-4-(dimethylamino)pyridine, 2,5-di-t-butyl-4 -(dimethylamino) pyridine, 1-(pyridin-4-yl) azocane and the like, 4-dimethylaminopyridine, 4-diethylaminopyridine, 4-dipropylaminopyridine, 4-dibutylaminopyridine, 4-dibenzyl Aminopyridine, 4-dihexylaminopyridine, 4-dihexylaminopyridine, 4-dioctylaminopyridine, 4-dinonylaminopyridine, 4-didecylaminopyridine, 4-undecylaminopyridine, 4-dodecylaminopyridine, 4- Dibenzylaminopyridine, 4-diphenylaminopyridine, 4-pyrrolidinopyridine, 4-piperidinopyridine, 4-(4-methylpiperidino)pyridine, 4-morpholinopyridine, 4-methylethylaminopyridine, 4-methylpropylamino Pyridine, 4-methylbenzylaminopyridine, 4-methylphenylaminopyridine are preferred, 4-(dimethylamino)pyridine (formula (5a) below), 4-pyrrolidinopyridine (formula (5b) below), 4-piperidine nopyridine (the following formula (5c)), 4-(4-methylpiperidino)pyridine (the following formula (5d)), 4-morpholinopyridine (the following formula (5e)), 4-piperazinopyridine (the following formula (5f) ) is more preferred, and 4-(dimethylamino)pyridine, 4-pyrrolidinopyridine, and 4-piperazinopyridine are even more preferred. These N-substituted aminopyridine compounds may be used singly or in combination.

The blending amount of the polymerization catalyst (C) is desirably 0.01% by weight or more and 10% by weight or less with respect to the total amount of the epoxy compound (A) and the compound (B). If it is less than 0.01% by weight, the polymerization reaction takes a long time, which may reduce the productivity, and may cause deactivation for some reason before the target molecular weight is reached. On the other hand, when it exceeds 10% by weight, while the polymerization reaction proceeds rapidly, the storage stability may be impaired, which may cause problems in process suitability. 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 0.03 to 5.0% by weight, still more preferably 0.05 to 1.0% by weight.

In the epoxy resin composition of the present invention, other catalysts may be used together with the N-substituted aminopyridine compound. Other catalysts are not particularly limited as long as they are catalysts used in the so-called "two-step method" for producing epoxy resins. Examples thereof include alkali metal compounds, organic phosphorus compounds, tertiary amines, quaternary ammonium salts, cyclic amines, imidazole compounds and the like. These other catalysts may be used alone or in combination of two or more. When used in a reinforcing fiber-containing epoxy resin composition, it is preferable not to contain other catalysts.

The epoxy resin composition of the present invention desirably does not contain an organic solvent, but may contain an organic solvent as a solvent for the polymerization catalyst 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). 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 may be inhibited. Further, if the organic solvent remains in the polymer, the mechanical properties and heat resistance are 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, more preferably 2% by weight or less, and particularly 1.5% by weight or less. desirable.

The progress of the polymerization of the epoxy resin composition of the present invention is preferably judged by the transition of the weight average molecular weight of the polymer (thermoplastic epoxy resin). 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. As a result, standard polymerization conditions for obtaining a polymer from an epoxy resin composition that allow the polymerization reaction to proceed sufficiently without overheating due to runaway or gelling due to side reactions are, for example, 130 to 130. A heating condition of 250° C. for 1 hour or more is preferable. Here, the physical property values of the polymers in the examples are the measured values of those polymerized under heating conditions of 160° C. for 1 hour.

The presence of fibers hinders the polymerization reaction of resins containing fibers, such as fiber-reinforced epoxy resin composites or prepregs. Is required. Therefore, the standard condition for polymerizing the fiber-reinforced epoxy resin composite or prepreg was heating at 160° C. for 4 hours.

The weight average molecular weight (Mw) of the polymer obtained by polymerizing the epoxy resin composition of the present invention 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, 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 40,000 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 4,000 g/eq. 200,000 g/eq. It is desirable that: Epoxy equivalent is 4,000 g/eq. If it is less than that, the polymerization may not proceed sufficiently. Epoxy equivalent weight of 200,000 g/eq. If it exceeds , the number of epoxy groups may be too small, which may adversely affect the adhesion to fibers. The epoxy equivalent is preferably 10,000 g/eq. 150,000 g/eq. Below, more preferably 20,000 g/eq. 100,000 g/eq. It is below.
The glass transition temperature (Tg) of the polymer is preferably 120°C or higher, more preferably 130°C or higher.

When a phosphorus-containing compound is used as a raw material, the phosphorus content of the polymer is preferably 1.0 to 6.0 wt%, more preferably 1.5 to 5.0 wt%, still more preferably 2.0 to 4.0% by weight.　

The impact strength of the polymer is evaluated by a notched Izod impact test (specifically, the measuring method described in Examples), and the impact strength is desirably 12 kJ/m ² or more.

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 epoxy resin 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 is obtained by mixing or impregnating the above epoxy resin composition and reinforcing fibers.

As a method for impregnating carbon fiber with the epoxy resin composition of the present invention and molding it, general FRP molding methods such as pultrusion molding, filament winding, RTM method, VaRTM method, hand lay-up method, PIF method, etc. can be used. can be done. 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 viscosity for coating the epoxy resin composition of the present invention is preferably 0.1 Pa s or more and 100 Pa s or less, more preferably 0.5 Pa s or more and 70 Pa s or less, still more preferably It is 1 Pa·s or more and 50 Pa·s or less. When the coating viscosity is less than 0.1 Pa·s, repeated coating is required to obtain the desired resin film thickness. When the coating viscosity exceeds 100 Pa·s, it becomes difficult to uniformly coat the desired resin film thickness. In addition, the measuring method complies with the conditions described in Examples.

The temperature for applying the epoxy resin composition of the present invention is preferably 120° C. or lower, more preferably 100° C. or lower, and still more preferably 85° C. or lower. There is no lower limit to the coating temperature as long as the viscosity is such that it can be applied.
When a rigid skeleton compound is used to improve the Tg of the polymer, it is necessary to raise the coating temperature in order to adjust the resin viscosity suitable for coating without adding a solvent. If the coating temperature exceeds 120° C., the viscosity of the resin will increase significantly due to the polymerization reaction, making stable coating difficult.
In the present invention, 85° C. was used as a standard condition as a temperature at which an epoxy resin composition having a thermoplastic epoxy resin Tg of 120° C. or higher has a viscosity suitable for coating.

The viscosity doubling time of the epoxy resin composition of the present invention at 85°C is preferably 20 minutes or longer, more preferably 30 minutes or longer, and still more preferably 60 minutes or longer. There is no upper limit to the preferred viscosity doubling time. If the viscosity doubling time is less than 20 minutes, the viscosity increases significantly during the coating process, making it difficult to achieve a stable coating thickness.

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.
It is preferable to use carbon fiber as the reinforcing fiber because a composite material having high strength and rigidity in a well-balanced manner can be obtained. The carbon fiber may be either PAN-based or pitch-based, but PAN-based is particularly preferable.

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. Regarding the ratio of the reinforcing fibers, if the reinforcing fibers are 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.

The epoxy resin composition of the present invention has excellent storage stability. Therefore, it can be applied to fields such as carbon fiber reinforced resins.

The present invention will be described in more detail below based on examples, 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 fluorene type epoxy resin (manufactured by Nippon Steel Chemical & Materials Co., Ltd., ESF300, epoxy equivalent 250)
A3: Bisphenol A type liquid epoxy resin (manufactured by Nippon Steel Chemical & Materials Co., Ltd., YD-128, epoxy equivalent 188)

[Phenol compounds and ester compounds]
B1: Bisphenol A (manufactured by Nippon Steel Chemical & Materials Co., Ltd., hydroxyl equivalent 114)
B2: 4,4'-bis(3,3,5-trimethylcyclohexylidene) bisphenol (manufactured by Honshu Chemical Industry Co., Ltd., BisP-HTG, hydroxyl equivalent 155)
B3: 4,4'-(1-phenylethylidene) bisphenol (manufactured by Honshu Chemical Industry Co., Ltd., BisP-AP, hydroxyl equivalent 145)
B4: 4,4'-cyclododecane-1-ylidene) bisphenol (manufactured by Honshu Chemical Industry Co., Ltd., BisP-CDE, hydroxyl equivalent 176)
B5: 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Co., Ltd., HCA-HQ, hydroxyl equivalent 162)
B6: Bifunctional acetylated compound obtained in Synthesis Example 1 (10-(2,5-diacetoxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, formula (4 ), phosphorus content 7.6%, acetyl group equivalent 204)

[Polymerization catalyst]
C1: 4-dimethylaminopyridine (manufactured by Tokyo Chemical Industry Co., Ltd., DMAP, formula (5a))

C2: 4-pyrrolidinopyridine (manufactured by Tokyo Chemical Industry Co., Ltd., formula (5b))

C3: 1-(4-pyridyl)piperazine (manufactured by Tokyo Chemical Industry Co., Ltd., formula (5f))

C4: 2,3-dihydro-1H-pyrrolo-[1,2-a]benzimidazole (manufactured by Shikoku Kasei Co., Ltd., TBZ)

C5: Tris (para-methoxyphenyl) phosphine (manufactured by Hokko Chemical Industry Co., Ltd., TPAP)

C6: Tris-o-tolylphosphine (manufactured by Hokko Chemical Industry Co., Ltd., TOTP)

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

The evaluation methods in the examples are as follows.

Compatibility:
Whether or not the phenol compound and the ester compound were uniformly melted in the epoxy resin was judged 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 phenol compound and the ester compound are uniformly dissolved in the epoxy resin.

Viscosity and viscosity doubling time:
Viscosity and viscosity doubling time at 85° C. were measured according to JIS K6870 and JIS K5600-2-3 standards. Measured with 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 flat plate of 20 mm diameter, and a gap between the plates of 0.5 mm. Further, when the temperature was maintained at 85° C., the time until the viscosity doubled from the initially measured viscosity was measured, and this was taken 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 judged that there is sufficient latency, so the measurement time is set to 60 minutes, and "60<" is indicated in that case.

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. A measurement sample was obtained by dissolving 0.1 g of solid content in 10 mL of THF, filtering through a 0.45 μm membrane filter, and using an injection amount of 20 μL. 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 standard, DSC Tmg (glass state and rubber state) when measured with a differential scanning calorimeter (manufactured by Hitachi High-Tech Science Co., Ltd., EXSTAR6000 DSC6200) at a temperature increase of 10 ° C./min. It was expressed as the temperature at the midpoint of the mutation curve relative to the tangent line.

Solvent solubility:
1 g of the 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. 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 measurement was performed according to the JIS K7110 standard notched Izod impact test. As a tester, a digital impact tester DG-UB type (manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used, and the lifting angle was set to 150°. A hammer having a nominal pendulum energy of 0.5J, 1J, or 3J was selected and used. The sample had a thickness of 4 mm, a length of 80 mm, and a width of 10 mm, and was notched to form an A notch. (Notch width: 8.0 mm, radius: 0.25 mm). A hammer was shaken off the sample, and the impact strength was calculated from the swing-up angle of the hammer after measurement.

Flexural strength and modulus:
It was measured at 90 degrees in a three-point bending test (method A) according to JIS K7074. A test machine (Autograph AGS-X manufactured by Shimadzu Science) was used, and the sample had a thickness of 2 mm, a length of 100 mm, a width of 15 mm, a bending span of 70 mm, and a test speed of 1 mm/min. .

Synthesis Example 1 (ester compound)
162 parts of bifunctional phenol compound B5, 105 parts of acetic anhydride, and 79 parts of pyridine are charged at room temperature into a glass reaction vessel equipped with a stirrer, 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 at 150° C. and 1.3 kPa (10 torr) to obtain 203 parts of the phosphorus-containing compound B6 represented by the above formula (4).

(precursor mixture)
722 parts of A1, 971 parts of A2, 500 parts of B1, and 500 parts of B2 were each weighed and pulverized and mixed using a Henschel mixer. Subsequently, melt mixing is performed using an S1KRC kneader (manufactured by Kurimoto, Ltd.) preheated to a barrel temperature of 190°C, the entire amount is collected in a metal can, and cooled to 85°C while stirring to obtain an epoxy resin composition. to obtain a precursor mixture (F1).

The blending amounts (parts) of the formulation in Table 1 were blended, and the precursor mixtures (F2 to F7) of the epoxy resin composition were obtained in the same procedure. The "molar ratio" in the table represents the equivalent ratio of the functional groups of the phenol compound and the ester compound to the epoxy groups of the epoxy resin.

Regarding F7, since the epoxy resin is liquid, it is pre-mixed using a planetary mixer and three rolls instead of a Henschel mixer, and then put into a kneader, preheating the barrel temperature of the kneader to 120 ° C. to perform melt mixing. The entire amount was collected in a metal can and cooled to 85° C. while stirring to obtain a precursor mixture (F7) of an epoxy resin composition.

Example 1
A polymerization catalyst solution was obtained by previously dissolving 0.1 part of C1 (polymerization catalyst) in 0.2 parts of D1 (organic solvent). 100 parts of the precursor mixture (F1) was placed in a planetary mixer set at 85° C., and the previous polymerization catalyst solution was added and mixed. After mixing, the mixture was quickly extracted and immediately cooled to 40° C. or less to obtain an epoxy resin composition (G1).

When the haze value (compatibility) of the epoxy resin composition (G1) was measured, it was found to be 5% or more and less than 10% (<10), and it was determined to be uniformly dissolved. The viscosity at 85° C. was measured to be 7.5 Pa·s, and the viscosity doubling time was 55 minutes.

The obtained epoxy resin composition G1 was heated to 85° C. with stirring, poured into an iron chromium-plated mold container with a clearance of 4 mm in advance, and thermally polymerized at 160° C. for 60 minutes in a hot air circulating oven. A polymer (H1), which is a thermoplastic resin, was obtained.
The resulting polymer had an Mw of 63,000, an Mn of 16,000, and a solvent solubility of ◯. Epoxy equivalent weight, glass transition temperature (Tg) and impact strength were measured and the results are also shown in Table 2.

Examples 2-9, Comparative Examples 1-7
Epoxy resin compositions and polymers (G2 to G16, H2 to H16) were obtained in the same manner as in Example 1 by blending in the amounts (parts) of the formulation shown in Table 2. G10 to G16 and H10 to H16 are comparative examples.
The physical properties of the obtained epoxy resin compositions and polymers (G2 to G16, H2 to H16) were measured in the same manner as in Example 1, and the evaluation results are shown in Table 2.

Example 10
A release paper that has been subjected to a release treatment is fixed on a hot plate preheated to 85°C so that the release surface faces upward, and 100 parts by weight of the epoxy resin composition (G1) obtained in Example 1 is removed. After being placed on the pattern paper, it was coated using a bar coater preheated to 85° C. so that the area weight of the resin was 79 g/m ² . Immediately after coating, the sheet was removed from the hot plate and air-cooled to obtain an epoxy resin composition sheet.
Subsequently, the carbon fibers (E) are laminated on the obtained epoxy resin composition sheet so that the area weight of the fibers is 153 g / m ² , and the surface pressure is 0 using a hot press preheated to 90 ° C. A pressure of 0.5 MPa was applied, and after 1 minute, it was taken out and air-cooled to obtain a prepreg (I1) having an Rc of 34%.

After laminating 13 sheets of prepreg (I1) with the same fiber orientation direction, release films were attached to the upper and lower surfaces and sandwiched between 3 mm thick aluminum plates. After wrapping the coupler and the aluminum plate with the prepreg sandwiched between them in a bag film, the coupler and the vacuum pump were connected to deaerate the air in the bag film. The bag was left still in a hot air circulating oven preheated to 160° C., and hardened while being vacuumed to mold a unidirectional fiber reinforced plastic (J1) having a thickness of 2 mm. The curing conditions were 160° C. and 240 minutes.

As a result of measuring the molecular weight of the resin component of the obtained unidirectionally reinforced fiber plastic (J1), Mw was 71,000 and Mn was 17,000. As a result of measuring the glass transition temperature (Tg) of the unidirectionally reinforced fiber plastic, it was 147°C. As a result of measuring the bending strength and bending elastic modulus, they were 76 MPa and 6.1 GPa.

The resulting unidirectionally reinforced fiber plastic (J1) was cut into pieces of 10 mm wide and 100 mm long, left to stand in a hot air circulating oven preheated to 200°C for 10 minutes, and then hand-bent to confirm secondary workability. By the way, it was confirmed that bending can be easily performed.

Comparative example 8
An epoxy resin composition (G17) was obtained by adding 20 parts of an organic solvent (D) to 100 parts of the epoxy resin composition (G13) obtained in Comparative Example 1 while preheating to 85°C and mixing. Ta. When the viscosity of the epoxy resin composition was measured at 65° C., it was 9.5 Pa·s, and the viscosity doubling time was 50 minutes.

An epoxy resin composition sheet, prepreg (I2), and unidirectional fiber reinforced plastic (J2) were obtained by the same procedure as in Example 10, except that the hot plate and bar coater were preheated to 65°C. The same evaluation as in Example 10 was performed. Table 3 shows the results.

From Table 3, it can be confirmed that the polymerizability, heat resistance and mechanical strength deteriorate when an organic solvent is added to the resin composition in order to adjust the coating viscosity and viscosity doubling time.
By using the epoxy resin composition of the present invention, the polymerization reaction proceeds sufficiently even in situ polymerization, and a thermoplastic CFRP having high heat resistance and a high fiber content can be obtained.

INDUSTRIAL APPLICABILITY The epoxy resin composition of the present invention is useful as an in-situ polymerizable resin composition, and can provide a thermoplastic fiber reinforced plastic (FRP) having a low void content and excellent heat resistance and impact resistance.

Claims (15)

1. An epoxy compound (A) having two epoxy groups in one molecule, a compound (B) having two phenolic hydroxyl groups and/or active ester groups as functional groups in one molecule, and a polymerization catalyst (C) are essential. As a component, an epoxy resin composition that becomes a thermoplastic epoxy resin by a polymerization reaction, and contains at least one N-substituted aminopyridine compound represented by the following formula (1) as a polymerization catalyst (C). An epoxy resin composition characterized by:
   

   

   In the formula, R1 and R2 are each independently a hydrocarbon group having 1 to 12 carbon atoms, and further R1 and R2 may be bonded together to form a heterocyclic ring, and the bonds are -O-, - NH- or -NR4- may be present. However, R4 is a hydrocarbon group having 1 to 12 carbon atoms. R3 is independently a hydrocarbon group having 1-12 carbon atoms and k is an integer of 0-4.
2. The epoxy resin composition according to claim 1, wherein the compounding amount of the epoxy compound (A) and the compound (B) is 0.90 to 1.10 mol of the compound (B) per 1 mol of the epoxy compound (A). .
3. The epoxy resin composition according to claim 1, wherein the polymerization catalyst (C) is used in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the total amount of the epoxy compound (A) and the compound (B).
4. Polymerization catalyst (C) from 4-(dimethylamino)pyridine, 4-pyrrolidinopyridine, 4-piperidinopyridine, 4-(4-methylpiperidino)pyridine, 4-morpholinopyridine, and 4-piperazinopyridine The epoxy resin composition according to claim 1, which is at least one compound selected from the group consisting of:
5. The epoxy resin composition according to claim 1, wherein part or all of the epoxy compound (A) and/or compound (B) is a phosphorus-containing compound.
6. The epoxy resin composition according to claim 5, wherein the thermoplastic epoxy resin obtained has a phosphorus content of 1 to 6% by weight.
7. If it does not contain an organic solvent, or if it contains an organic solvent, the content of the organic solvent is 0.01% by weight or more and 10% by weight or less of the epoxy resin composition, and the viscosity when heated to 85° C. is 0.00%. The epoxy resin composition according to claim 1, wherein the viscosity is 1 Pa·s or more and 100 Pa·s or less.
8. The epoxy equivalent of the obtained thermoplastic epoxy resin is 4,000 to 200,000 g/eq. The epoxy resin composition according to claim 1.
9. A reinforcing fiber-containing epoxy resin composition comprising the epoxy resin composition according to any one of claims 1 to 8 and reinforcing fibers.
10. The reinforcing fiber-containing epoxy resin composition according to claim 9, which contains 50 to 80% by weight of carbon fiber as the reinforcing fiber.
11. A prepreg characterized by comprising a mixture containing the epoxy resin composition according to any one of claims 1 to 8 and reinforcing fibers.
12. The prepreg according to claim 11, which contains 50 to 80% by weight of carbon fibers as reinforcing fibers.
13. A fiber-reinforced plastic using the reinforcing fiber-containing epoxy resin composition according to claim 9.
14. A fiber-reinforced plastic using the prepreg according to claim 11.
15. A thermoplastic epoxy resin obtained from the epoxy resin composition according to any one of claims 1 to 8, having a weight average molecular weight of 30,000 to 200,000 and measured by a notched Izod impact test. A thermoplastic epoxy resin having an impact strength of 12 kJ/m ² or more.