Thermosetting resin composition, cured product thereof, fiber-reinforced composite material, and production method for molded body

Abstract

Provide are: a thermosetting resin composition containing (A) an epoxy resin that does not include a polybutadiene structure, (B) a (meth)acrylate compound, (C) a reactive diluent, (D) an epoxy resin curing agent, and (E) a thermal radical polymerization initiator; a cured product thereof; a fiber-reinforced composite material containing the cured product and reinforcing fibers; and a production method for a molded body including the fiber-reinforced composite material.

Description

Thermosetting resin composition and cured product thereof, fiber-reinforced composite material, and method for producing molded article

[0001] The present invention relates to a thermosetting resin composition and a cured product thereof, a fiber-reinforced composite material, and a method for producing a molded article containing the fiber-reinforced composite material.

[0002] Fiber-reinforced composite materials (hereinafter also referred to as "FRPs (Fiber Reinforced Plastics)") have attracted attention as alternative materials to metals due to their extremely high elastic modulus and strength. Demand for FRPs is expected to accelerate in applications such as automotive structural materials, wind power generation blades, pressure vessels, and aerospace. Demand for the reinforcing fibers used in FRPs and matrix resins such as epoxy resins has also been increasing in recent years.

[0003] As a method for producing a fiber-reinforced composite material in which the matrix resin is a cured product of a thermosetting resin composition, a method is known in which a prepreg is produced by pre-impregnating reinforcing fibers with the thermosetting resin composition, and then the prepreg is used to mold and cure the material.

[0004] Prepregs and curable resin compositions suitable for prepregs have also been studied. For example, Patent Document 1 discloses a prepreg useful for molding high-strength, high-toughness fiber-reinforced plastics, which includes a carbon fiber and a matrix resin. The matrix resin is a curable resin composition containing a bisphenol-type epoxy resin, a difunctional or higher (meth)acrylate compound, and a curing agent containing dicyandiamide and a radical polymerization agent. The cured product of the curable resin composition has a predetermined flexural modulus and elongation at break. Patent Document 2 also discloses a curable resin composition for prepregs useful for molding high-strength, high-toughness fiber-reinforced plastics, which includes two epoxy resins, a difunctional or higher (meth)acrylate compound, and a curing agent that meets predetermined requirements.

[0005] Japanese Patent No. 6993549 Japanese Patent Application Laid-Open No. 2022-27815

[0006] The thermosetting resin compositions for prepregs disclosed in Patent Documents 1 and 2 are often relatively viscous, from the viewpoint of ease of prepreg storage, etc. On the other hand, depending on the manufacturing method of a fiber-reinforced composite material or a molded article containing the same, the thermosetting resin composition used may be required to have a low viscosity. For example, in the production of fiber-reinforced composite materials using pultrusion molding or filament winding molding, the process involves immersing reinforcing fibers in a resin bath filled with the thermosetting resin composition to impregnate the composition, introducing the reinforcing fibers into a mold or molding by winding, and then heat-curing the reinforcing fibers. In these manufacturing methods, the steps from impregnation of the reinforcing fibers with the thermosetting resin composition to heat-curing are performed continuously or intermittently. Therefore, unlike when using prepregs, an increased impregnation rate of the thermosetting resin composition into the reinforcing fibers is required. From this perspective, it is desirable for the thermosetting resin composition used to have a low viscosity. Furthermore, the production of fiber-reinforced composite materials using the Vacuum Assisted Resin Transfer Molding (Va-RTM) method includes the steps of placing reinforcing fibers in a mold, filling the mold with a thermosetting resin composition, and impregnating the reinforcing fibers with the thermosetting resin composition. In this process, a low viscosity thermosetting resin composition is desirable from the viewpoint of improving the productivity of fiber-reinforced composite materials by increasing the rate at which the thermosetting resin composition is filled into the mold and the rate at which the reinforcing fibers are impregnated. Furthermore, in the pultrusion molding method and the filament winding molding method, if the thermosetting resin composition is fast-curing, there is a problem that the thermosetting resin composition will harden in the resin bath. On the other hand, in the Va-RTM method, depending on the shape or size of the fiber-reinforced composite material to be produced, it may take several tens of minutes to fill the thermosetting resin composition into the mold. Therefore, the thermosetting resin composition is required to have a long pot life.

[0007] Furthermore, in order to ensure the heat resistance and high toughness of the fiber-reinforced composite material produced, the thermosetting resin composition used in the production thereof is required to have a high glass transition temperature and high elongation in the cured product. However, the techniques disclosed in Patent Documents 1 and 2 have difficulty in satisfying all of the above required properties.

[0008] An object of the present invention is to provide a thermosetting resin composition that has a low viscosity and a long pot life and that can give a cured product with a high glass transition temperature and elongation; a cured product thereof; a fiber-reinforced composite material containing the cured product and reinforcing fibers; and a method for producing a molded article containing the fiber-reinforced composite material.

[0009] The present inventors have found that the above-mentioned problems can be solved by a thermosetting resin composition containing a predetermined epoxy resin, a (meth)acrylate compound, a reactive diluent, an epoxy resin curing agent, and a thermal radical polymerization initiator. Specifically, the present invention relates to the following: [1] A thermosetting resin composition containing: component (A): an epoxy resin not containing a polybutadiene structure; component (B): a (meth)acrylate compound; component (C): a reactive diluent; component (D): an epoxy resin curing agent; and component (E): a thermal radical polymerization initiator. [2] The thermosetting resin composition according to [1], wherein the viscosity of component (C) at 20°C is 200 mPa·s or less. [3] The thermosetting resin composition according to [1] or [2], wherein the content of component (C) in the thermosetting resin composition is 1 to 50 mass%. [4] The thermosetting resin composition according to any one of [1] to [3], wherein the component (B) comprises component (B1): poly(butadiene-co-acrylonitrile) having (meth)acryloyloxy groups at both ends. [5] The thermosetting resin composition according to any one of [1] to [4], wherein the component (B) comprises component (B2): a polyfunctional (meth)acrylate having an aromatic ring. [6] The thermosetting resin composition according to any one of [1] to [5], wherein the component (C) comprises a compound having two or more glycidyl groups. [7] The thermosetting resin composition according to any one of [1] to [6], wherein the component (D) comprises a boron amine complex. [8] The thermosetting resin composition according to [7], wherein the amine component in the boron amine complex is a trialkylamine. [9] The thermosetting resin composition according to any one of [1] to [8], wherein the viscosity of the thermosetting resin composition at 25°C is 1,000 mPa s or less.

[10] A cured product of the thermosetting resin composition according to any one of [1] to [9].

[11] A fiber-reinforced composite material comprising the cured product according to

[10] and reinforcing fibers.

[12] The fiber-reinforced composite material according to

[11] , wherein the reinforcing fibers are at least one type selected from the group consisting of carbon fibers, glass fibers, and basalt fibers.

[13] A method for producing a molded article containing the fiber-reinforced composite material according to

[11] or

[12] , the method comprising any one of a pultrusion molding method, a Va-RTM method, or a filament winding molding method.

[0010] According to the present invention, it is possible to provide a thermosetting resin composition that has a low viscosity and a long pot life and that can give a cured product with a high glass transition temperature and elongation; a cured product thereof; a fiber-reinforced composite material containing the cured product and reinforcing fibers; and a method for producing a molded article containing the fiber-reinforced composite material.

[0011] [Definitions] In this specification, "(meth)acrylate" includes both acrylate and methacrylate. The same applies to "(meth)acryloyloxy group", "(meth)acrylic acid", etc. In this specification, "room temperature" means 23°C unless otherwise specified.

[0012] [Thermosetting resin composition] The thermosetting resin composition of the present invention (hereinafter also simply referred to as "the composition of the present invention") contains: Component (A): an epoxy resin not containing a polybutadiene structure, Component (B): a (meth)acrylate compound, Component (C): a reactive diluent, Component (D): an epoxy resin curing agent, and Component (E): a thermal radical polymerization initiator. Because the composition of the present invention has the above-mentioned configuration, it has a low viscosity and a long pot life, and further, a cured product having a high glass transition temperature and elongation can be obtained.

[0013] The reason why the above-mentioned effects are achieved in the present invention is unclear, but is thought to be as follows. The thermosetting resin composition of the present invention contains an epoxy resin (A) (hereinafter simply referred to as "epoxy resin (A)") that does not contain a polybutadiene structure as a thermosetting resin, and a (meth)acrylate compound (B). The epoxy resin curing agent (D) serves as a curing agent for component (A), and the thermal radical polymerization initiator (E) acts as a polymerization initiator for curing component (B) by thermal polymerization. Thermosetting (epoxy) resin compositions comprising an epoxy resin and an epoxy resin curing agent generally exhibit excellent curability, heat resistance, etc., but the low elongation of the cured product has been a problem for applications requiring high toughness. Furthermore, because epoxy resin compositions typically cure quickly, an improvement in pot life has also been necessary for thermosetting resin compositions used in fiber-reinforced composites produced by pultrusion molding, Va-RTM, and the like. The thermosetting resin composition of the present invention is a hybrid of an epoxy resin curing system of component (A)-component (D) and a (meth)acrylate curing system of component (B)-component (E), which is believed to improve the elongation of the cured product compared to a single epoxy resin curing system, and further suppress a decrease in the pot life of the composition due to the high reactivity of component (A) and component (D). Furthermore, if component (A) used in the present invention is a modified epoxy resin containing a polybutadiene structure, the viscosity of the resulting thermosetting resin composition may increase and the glass transition temperature of the cured product may decrease. In the present invention, it is believed that a thermosetting resin composition with a lower viscosity can be obtained by using a component (A) that is not a modified epoxy resin containing a polybutadiene structure and by including a reactive diluent (C) in the thermosetting resin composition.

[0014] <Component (A): Epoxy Resin Containing No Polybutadiene Structure> From the viewpoints of improving curability and the Tg of the resulting cured product, the epoxy resin (A) used in the present invention is preferably a polyfunctional epoxy resin containing no polybutadiene structure and having two or more epoxy groups. Furthermore, the epoxy resin (A) is preferably a compound containing no (meth)acroyloxy group.

[0015] The epoxy resin (A) used in the present invention is a compound other than the reactive diluent (C) described below. From this viewpoint, the viscosity of the epoxy resin (A) at 20°C is preferably greater than 200 mPa·s, more preferably 400 mPa·s or greater, and even more preferably 500 mPa·s or greater. The viscosity of the epoxy resin (A) at 20°C can be measured using an E-type viscometer, as with the viscosity of the component (C) described below, specifically by the method described in the Examples. Furthermore, "an epoxy resin having a viscosity of greater than 200 mPa·s at 20°C" also includes epoxy resins that are solid at 20°C.

[0016] From the viewpoint of improving the Tg of the cured product, the epoxy resin (A) is more preferably a polyfunctional epoxy resin containing an aromatic ring or an alicyclic structure in the molecule. Specific examples of the epoxy resin (A) include at least one selected from the group consisting of polyfunctional epoxy resins having a glycidylamino group derived from meta-xylylenediamine, polyfunctional epoxy resins having a glycidylamino group derived from para-xylylenediamine, polyfunctional epoxy resins having a glycidylamino group derived from 1,3-bis(aminomethyl)cyclohexane, polyfunctional epoxy resins having a glycidylamino group derived from 1,4-bis(aminomethyl)cyclohexane, polyfunctional epoxy resins having a glycidylamino group derived from diaminodiphenylmethane, polyfunctional epoxy resins having a glycidylamino group and / or a glycidyloxy group derived from para-aminophenol, polyfunctional epoxy resins having a glycidyloxy group derived from resorcinol, polyfunctional epoxy resins having a glycidyloxy group derived from bisphenol A or hydrogenated products thereof, polyfunctional epoxy resins having a glycidyloxy group derived from bisphenol F or hydrogenated products thereof, and polyfunctional epoxy resins having a glycidyloxy group derived from phenol novolac. The polyfunctional epoxy resins may be used alone or in combination of two or more.

[0017] Among the above, from the viewpoint of improving the Tg of the cured product, the epoxy resin (A) is preferably one whose main component is at least one selected from the group consisting of polyfunctional epoxy resins having glycidylamino groups derived from meta-xylylenediamine, polyfunctional epoxy resins having glycidylamino groups derived from para-xylylenediamine, polyfunctional epoxy resins having glycidyloxy groups derived from bisphenol A, and polyfunctional epoxy resins having glycidyloxy groups derived from bisphenol F, and more preferably one whose main component is at least one selected from the group consisting of epoxy resins having glycidyloxy groups derived from bisphenol A and epoxy resins having glycidyloxy groups derived from bisphenol F. Here, the term "main component" means that the resin may contain other components within the scope of the present invention, and preferably represents 50 to 100 mass%, more preferably 70 to 100 mass%, and even more preferably 90 to 100 mass% of the total.

[0018] The polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A is bisphenol A diglycidyl ether or an oligomer thereof, and is preferably a polyfunctional epoxy resin represented by the following structural formula: (In the above formula, s represents the average number of repeating units and is a number from 0 to 20.) From the viewpoint of improving the Tg of the cured product, s in the above formula is preferably 0 to 15, more preferably 0 to 10, even more preferably 0 to 5.0, and still more preferably 0 to 2.0.

[0019] The polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol F is bisphenol F diglycidyl ether or an oligomer thereof, and is preferably a polyfunctional epoxy resin represented by the following structural formula: (In the above formula, t represents the average number of repeating units and is a number from 0 to 20.) From the viewpoint of improving the Tg of the cured product, t in the above formula is preferably 0 to 15, more preferably 0 to 10, even more preferably 0 to 5.0, and still more preferably 0 to 2.0.

[0020] The epoxy resin (A) may be either a solid epoxy resin or a liquid epoxy resin, but preferably contains a liquid epoxy resin from the viewpoint of obtaining a low-viscosity thermosetting resin composition. The term "liquid epoxy resin" refers to an epoxy resin that has fluidity at 25°C. From the viewpoint of obtaining a low-viscosity thermosetting resin composition, the content of the liquid epoxy resin in the epoxy resin (A) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 85% by mass or more, and still more preferably 90% by mass or more, but not more than 100% by mass.

[0021] The epoxy equivalent (functional group equivalent) of the epoxy resin (A) is not particularly limited, but from the viewpoint of obtaining a low-viscosity thermosetting resin composition, it is preferably 1,500 g / equivalent or less, more preferably 1,200 g / equivalent or less, even more preferably 1,000 g / equivalent or less, still more preferably 800 g / equivalent or less, still more preferably 500 g / equivalent or less, still more preferably 350 g / equivalent or less, and still more preferably 250 g / equivalent or less, and from the viewpoint of improving curability and pot life, it is preferably 120 g / equivalent or more, more preferably 140 g / equivalent or more, and even more preferably 150 g / equivalent or more. When a mixture of two or more epoxy resins is used as the epoxy resin (A), the epoxy equivalent of the epoxy resin (A) means the epoxy equivalent of the mixture.

[0022] As the component (A), a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A, commercially available products such as "jER825," "jER827," "jER828," "jER834," and "jER1001," manufactured by Mitsubishi Chemical Corporation, can be used. As the polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol F, commercially available products such as "jER806," "jER806H," "jER807," "jER4005P," "jER4007P," and "jER4010P," manufactured by Mitsubishi Chemical Corporation, can be used.

[0023] <Component (B): (Meth)Acrylate Compound> Component (B) used in the present invention may be a compound that does not contain a glycidyl group and has at least one (meth)acryloyloxy group. From the viewpoint of improving the Tg and elongation of the cured product, component (B) preferably contains a polyfunctional (meth)acrylate compound having two or more (meth)acryloyloxy groups. The number of (meth)acryloyloxy groups in the polyfunctional (meth)acrylate compound is preferably 2 to 6, more preferably 2 to 4, even more preferably 2 to 3, and still more preferably 2. If the number of (meth)acryloyloxy groups in the polyfunctional (meth)acrylate compound is 2 or more, it is likely to contribute to an improvement in the Tg of the cured product, and if it is 6 or less, it is possible to suppress a decrease in the elongation of the cured product.

[0024] From the viewpoint of improving the Tg and elongation of the cured product, the content of the polyfunctional (meth)acrylate compound in component (B) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and still more preferably 98% by mass or more, but is 100% by mass or less.

[0025] From the viewpoint of improving the Tg and elongation of the cured product, component (B) preferably contains, as a polyfunctional (meth)acrylate compound, at least one selected from the group consisting of component (B1): poly(butadiene-co-acrylonitrile) having (meth)acryloyloxy groups at both ends; and component (B2): polyfunctional (meth)acrylate having an aromatic ring, and more preferably contains both component (B1) and component (B2).

[0026] (Component (B1): Poly(butadiene-co-acrylonitrile) terminated with (meth)acryloyloxy groups at both ends) From the viewpoint of improving the elongation of the cured product, component (B) preferably contains, as a polyfunctional (meth)acrylate compound, component (B1): poly(butadiene-co-acrylonitrile) terminated with (meth)acryloyloxy groups at both ends. Because component (B1) has a highly flexible structure, it is believed that it can suppress a decrease in elongation even in cured products with a high crosslink density. Component (B1) used in the present invention is a di(meth)acrylate having (meth)acryloyloxy groups at both ends of a main chain containing a copolymer structure of butadiene and acrylonitrile. From the viewpoint of improving the Tg and elongation of the cured product, the content of acrylonitrile-derived structural units in component (B1) is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, and even more preferably 10 to 25% by mass. The weight-average molecular weight (Mw) of component (B1) is preferably 1,000 to 30,000, more preferably 2,000 to 10,000, and even more preferably 3,000 to 8,000. An Mw of 1,000 or more contributes to improving the elongation of the cured product, while an Mw of 30,000 or less contributes to suppressing a decrease in the Tg of the cured product. Commercially available products such as "Hypro 1300X33LC" manufactured by Chori GLEX can also be used as component (B1).

[0027] The content of component (B1) in component (B) is preferably 1 to 70 mass%, more preferably 5 to 60 mass%, even more preferably 10 to 60 mass%, still more preferably 15 to 60 mass%, still more preferably 15 to 50 mass%, still more preferably 15 to 40 mass%, still more preferably 15 to 30 mass%, still more preferably 15 to 25 mass%, and still more preferably 15 to 20 mass%. When the content of component (B1) in component (B) is 1 mass% or more, it is likely to contribute to improving the elongation of the cured product, and when it is 70 mass% or less, it is possible to suppress a decrease in the Tg of the cured product.

[0028] (Component (B2): Polyfunctional (meth)acrylate having an aromatic ring) From the viewpoint of improving the Tg and elongation of the cured product, component (B) preferably contains, as a polyfunctional (meth)acrylate compound, component (B2): a polyfunctional (meth)acrylate having an aromatic ring. The number of (meth)acryloyloxy groups in component (B2) is preferably 2 to 6, more preferably 2 to 4, even more preferably 2 to 3, and still more preferably 2. If the number of (meth)acryloyloxy groups in component (B2) is 2 or more, this tends to contribute to an improvement in the Tg of the cured product, while if it is 6 or less, a decrease in the elongation of the cured product can be suppressed.

[0029] The aromatic ring contained in component (B2) may be a single ring or a condensed ring, and examples thereof include, but are not limited to, a benzene ring, a naphthalene ring, an anthracene ring, and a tetracene ring. Among these, at least one ring selected from the group consisting of a benzene ring and a naphthalene ring is preferred, and a benzene ring is more preferred. The number of aromatic rings contained in component (B2) may be one or more, and from the viewpoint of improving the Tg and elongation of the cured product, it is preferably two or more.

[0030] Specific examples of the polyfunctional (meth)acrylate having an aromatic ring, which is used as component (B2), include polyfunctional (meth)acrylates having a structure derived from biphenol, polyfunctional (meth)acrylates having a structure derived from bisphenol A, polyfunctional (meth)acrylates having a structure derived from bisphenol F, polyfunctional (meth)acrylates having a fluorene structure, and polyfunctional (meth)acrylates having a structure derived from an aromatic hydrocarbon formaldehyde resin, and one or more of these can be used. Among the above, from the viewpoint of improving the Tg and elongation of the cured product, component (B2) preferably comprises at least one selected from the group consisting of polyfunctional (meth)acrylates having a structure derived from bisphenol A, polyfunctional (meth)acrylates having a structure derived from bisphenol F, and polyfunctional (meth)acrylates having a structure derived from an aromatic hydrocarbon formaldehyde resin, more preferably at least one selected from the group consisting of polyfunctional (meth)acrylates having a structure derived from bisphenol A and polyfunctional (meth)acrylates having a structure derived from an aromatic hydrocarbon formaldehyde resin, and even more preferably a polyfunctional (meth)acrylate having a structure derived from bisphenol A. The polyfunctional (meth)acrylate may be any of polyester (meth)acrylates having a main skeleton derived from a polyol, epoxy (meth)acrylates having a main skeleton derived from an epoxy compound, and urethane (meth)acrylates having main skeletons derived from a polyisocyanate and a polyol, but is preferably at least one selected from the group consisting of polyester (meth)acrylates and epoxy (meth)acrylates.

[0031] The aromatic hydrocarbon-formaldehyde resin is a resin obtained by reacting an aromatic hydrocarbon with formaldehyde. Examples of the aromatic hydrocarbon include at least one selected from the group consisting of benzene, xylene, toluene, mesitylene, pseudocumene, ethylbenzene, propylbenzene, decylbenzene, cyclohexylbenzene, biphenyl, methylbiphenyl, naphthalene, methylnaphthalene, dimethylnaphthalene, ethylnaphthalene, anthracene, methylanthracene, dimethylanthracene, ethylanthracene, and binaphthyl. Preferably, at least one selected from the group consisting of xylene, toluene, and mesitylene is used, and more preferably, xylene. Xylene-formaldehyde resins are also referred to as "xylene resins," toluene-formaldehyde resins as "toluene resins," and mesitylene-formaldehyde resins as "mesitylene resins."

[0032] From the viewpoint of improving the Tg and elongation of the cured product, the polyfunctional (meth)acrylate having an aromatic ring used as component (B2) more preferably includes at least one selected from the group consisting of a compound represented by the following general formula (B2-1), a compound represented by the following general formula (B2-2), a compound represented by the following general formula (B2-3), and a polyfunctional (meth)acrylate having a structure derived from an aromatic hydrocarbon formaldehyde resin, and even more preferably includes a compound represented by the following general formula (B2-1): In the formula, R １ and R ２ each independently represents a hydrogen atom or a methyl group, R ３ and R ４ each independently represents a hydrogen atom or a methyl group, k and l each independently represent the number of repeating units and are a number from 0 to 20. In the formula, R １ ~R ４ is the same as above. In the formula, R １ and R ２ is the same as above, and R ５is an alkylene group having 2 to 6 carbon atoms. X is a residue of a diisocyanate, and Y is a residue of a diol. Either X or Y contains an aromatic ring. r represents the number of repeating units and is a number of 1 or more. The r+1 Xs and the r Ys may all be the same or different from one another.

[0033] In the general formula (B2-1), R １ and R ２ is preferably a methyl group, and R ３ and R ４ is preferably a methyl group. From the viewpoint of improving the Tg and elongation of the cured product, k and l in the general formula (B2-1) are each independently a number of preferably 1 to 15, more preferably 1 to 10, and even more preferably 2 to 6. Furthermore, k+l is a number of 0 to 40, and from the viewpoint of improving the Tg and elongation of the cured product, it is preferably a number of 2 to 30, more preferably 2 to 20, even more preferably 4 to 20, and still more preferably 8 to 20.

[0034] As the compound represented by the general formula (B2-1), commercially available products such as "BPE-500" and "BPE-900" manufactured by Shin-Nakamura Chemical Co., Ltd. can be used.

[0035] In the general formula (B2-2), R １ and R ２ is preferably a methyl group, and R ３ and R ４ is preferably a methyl group. Specific examples of the compound represented by general formula (B2-2) include a (meth)acrylic acid adduct of bisphenol A diglycidyl ether [bisphenol A-type epoxy di(meth)acrylate] and a (meth)acrylic acid adduct of bisphenol F diglycidyl ether [bisphenol F-type epoxy di(meth)acrylate], of which bisphenol A-type epoxy di(meth)acrylate is preferred, and bisphenol A-type epoxy dimethacrylate is more preferred.

[0036] In the general formula (B2-3), R １ and R ２ is preferably a methyl group. ５is an alkylene group having 2 to 6 carbon atoms, and the alkylene group may be either a straight chain or a branched chain. ５ is preferably an alkylene group having 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

[0037] X in the general formula (B2-3) is a divalent group and is a residue of a diisocyanate represented by OCN-X-NCO. Examples of the diisocyanate include aliphatic chain diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, 1,3-pentamethylene diisocyanate, 1,5-pentamethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2-methyl-1,5-pentamethylene diisocyanate, and 3-methyl-1,5-pentamethylene diisocyanate; 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, and methyl-2-methyl-1,5-pentamethylene diisocyanate; aliphatic diisocyanates containing an alicyclic structure such as methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,2-bis(isocyanatemethyl)cyclohexane, 1,3-bis(isocyanatemethyl)cyclohexane, isophorone diisocyanate, and norbornane diisocyanate; and diisocyanates containing an aromatic ring such as m-phenylene diisocyanate, p-phenylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthylene-1,4-diisocyanate, and naphthylene-1,5-diisocyanate. These diisocyanates can be used alone or in combination.

[0038] When Y in the general formula (B2-3) does not contain an aromatic ring, the diisocyanate is a diisocyanate containing an aromatic ring. When Y in the general formula (B2-3) contains an aromatic ring, from the viewpoint of improving the elongation percentage of the cured product, the diisocyanate is preferably at least one selected from the group consisting of chain aliphatic diisocyanates and aliphatic diisocyanates containing an alicyclic structure, more preferably at least one selected from the group consisting of hexamethylene diisocyanate, 1,2-bis(isocyanatemethyl)cyclohexane, 1,3-bis(isocyanatemethyl)cyclohexane, and isophorone diisocyanate, and even more preferably hexamethylene diisocyanate.

[0039] In the general formula (B2-3), Y is a divalent group and is a residue of a diol represented by HO-Y-OH. Examples of such diols include linear aliphatic diols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; diols containing an alicyclic structure such as cyclohexanedimethanol and tricyclodecanedimethanol; and diols containing an aromatic ring such as biphenol, bisphenol A, bisphenol F, and bisphenoxyfluoreneethanol, as well as diols obtained by adding ethylene oxide, propylene oxide, or caprolactone to these diols. These diols may be used alone or in combination.

[0040] From the viewpoint of improving the Tg and elongation of the cured product, the diol is preferably at least one selected from the group consisting of chain aliphatic diols and diols containing an aromatic ring, more preferably a diol containing an aromatic ring, and even more preferably at least one selected from the group consisting of bisphenol A, bisphenol F, and diols obtained by adding ethylene oxide or propylene oxide to these.

[0041] Y in the general formula (B2-3) is more preferably a divalent group represented by the following general formula (Y1). In the formula, R ６ and R ７ each independently represents a hydrogen atom or a methyl group, preferably a methyl group. p and q represent the number of repeating units, each independently representing a number from 0 to 20. * represents a bond.

[0042] In the general formula (B2-3), r is a number of 1 or more, and preferably a number of 1 or more and 200 or less.

[0043] Furthermore, as the polyfunctional (meth)acrylate having a structure derived from an aromatic hydrocarbon formaldehyde resin, which is used as component (B2), commercially available products such as "NIKANOL XUAT" (urethane acrylate xylene resin) manufactured by Fudow Co., Ltd. can be used.

[0044] The content of component (B2) in component (B) is preferably 30 to 99% by mass, more preferably 40 to 95% by mass, even more preferably 40 to 90% by mass, still more preferably 40 to 85% by mass, even more preferably 50 to 85% by mass, even more preferably 60 to 85% by mass, even more preferably 70 to 85% by mass, even more preferably 75 to 85% by mass, and even more preferably 80 to 85% by mass. If the content of component (B2) in component (B) is 30% by mass or more, it is likely to contribute to an improvement in the Tg of the cured product, and if it is 99% by mass or less, the elongation of the cured product can be maintained.

[0045] In addition to components (B1) and (B2), component (B) may also contain a monofunctional (meth)acrylate and a polyfunctional (meth)acrylate other than components (B1) and (B2). However, from the viewpoint of improving the Tg and elongation of the cured product, the total content of components (B1) and (B2) in component (B) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more, but 100% by mass or less.

[0046] <Component (C): Reactive Diluent> Component (C): reactive diluent used in the present invention is a component other than component (A) and component (B), and is a compound having at least one reactive functional group and a viscosity of 200 mPa·s or less at 20°C. From the viewpoint of low viscosity, the viscosity of component (C) at 20°C is preferably 150 mPa·s or less, more preferably 130 mPa·s or less, even more preferably 120 mPa·s or less, still more preferably 100 mPa·s or less, still more preferably 80 mPa·s or less, still more preferably 60 mPa·s or less, still more preferably 50 mPa·s or less, and still more preferably 30 mPa·s or less. Furthermore, from the viewpoint of suppressing volatilization, the viscosity of component (C) at 20°C is preferably 2 mPa·s or more, more preferably 4 mPa·s or more. The viscosity of component (C) at 20°C can be measured using an E-type viscometer, specifically by the method described in the examples.

[0047] From the viewpoint of improving the Tg and elongation of the cured product, component (C) preferably has one or more reactive functional groups, more preferably two or more. From the viewpoint of achieving low viscosity and a long pot life and improving the Tg and elongation of the cured product, the number of reactive functional groups in component (C) is more preferably 2 to 4, even more preferably 2 to 3, and still more preferably 2. From the viewpoint of achieving low viscosity and a long pot life and improving the Tg and elongation of the cured product, the reactive functional group in component (C) is preferably a glycidyl group. That is, component (C) preferably contains a compound having one or more glycidyl groups, more preferably two or more glycidyl groups, and even more preferably contains a compound having 2 to 4, even more preferably 2 to 3, and still more preferably 2 glycidyl groups. In component (C), from the viewpoints of achieving low viscosity and a long pot life, and of improving the Tg and elongation of the cured product, the content of the compound having two or more glycidyl groups is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 95% by mass or more, but not more than 100% by mass.

[0048] From the viewpoint of low viscosity, component (C) is preferably a compound that does not have a ring structure. The ring structure here includes an aromatic ring, an alicyclic structure, a heterocyclic structure, and the like.

[0049] From the viewpoints of achieving a long pot life and improving the Tg of the cured product, the functional group equivalent of component (C) is preferably 90 g / equivalent or more, more preferably 100 g / equivalent or more, and even more preferably 110 g / equivalent or more. Furthermore, from the viewpoint of low viscosity, it is preferably 500 g / equivalent or less, more preferably 400 g / equivalent or less, even more preferably 300 g / equivalent or less, still more preferably 200 g / equivalent or less, and even more preferably 150 g / equivalent or less. The functional group equivalent of component (C) refers to the mass (g) of component (C) per mole of reactive functional group, and when the reactive functional group is a glycidyl group, it refers to the epoxy equivalent.

[0050] Specific examples of the compound having only one glycidyl group among the component (C) include alkyl monoglycidyl ethers such as butyl glycidyl ether and 2-ethylhexyl glycidyl ether; phenyl glycidyl ether, 2-phenylphenol glycidyl ether, and phenol (EO) ５ and aromatic ring-containing monoglycidyl ethers such as alkyl glycidyl ether, phenyl glycidyl ether, and p-tert-butylphenyl glycidyl ether; and one or more of these can be used. Among these, from the viewpoint of low viscosity, the compound having only one glycidyl group preferably includes at least one selected from the group consisting of alkyl monoglycidyl ether, phenyl glycidyl ether, and p-tert-butylphenyl glycidyl ether, and more preferably includes alkyl monoglycidyl ether.

[0051] Of the component (C), examples of the compound having two or more glycidyl groups include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, α,ω-linear alkanediol diglycidyl ethers having 3 or more carbon atoms, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, and diglycerol polyglycidyl ether, and one or more of these can be used.

[0052] The number of polyoxyalkylene units in the polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether is preferably 2 to 20, more preferably 2 to 15, even more preferably 2 to 10, and still more preferably 2 to 6, from the viewpoint of low viscosity.

[0053] From the viewpoint of low viscosity, the α,ω-linear alkanediol diglycidyl ether having 3 or more carbon atoms is preferably an α,ω-linear alkanediol diglycidyl ether having 3 to 12 carbon atoms, more preferably an α,ω-linear alkanediol diglycidyl ether having 4 to 8 carbon atoms. Examples of the α,ω-linear alkanediol diglycidyl ether having 3 or more carbon atoms include 1,3-propanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,8-octanediol diglycidyl ether, 1,10-decanediol diglycidyl ether, and 1,12-dodecanediol diglycidyl ether.

[0054] Among the above, from the viewpoints of achieving low viscosity and a long pot life, and improving the Tg and elongation of the cured product, component (C) preferably contains a compound having two or more glycidyl groups, more preferably contains a compound having two or more glycidyl groups but not having a ring structure, even more preferably contains at least one selected from the group consisting of ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and α,ω-linear alkanediol diglycidyl ethers having 3 or more carbon atoms, and even more preferably contains ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and α,ω-linear alkanediol diglycidyl ethers having 3 or more carbon atoms. The glycerin-modified α,ω-alkanediol diglycidyl ether preferably contains at least one selected from the group consisting of ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and neopentyl glycol diglycidyl ether, and more preferably contains at least one selected from the group consisting of ethylene glycol diglycidyl ether and neopentyl glycol diglycidyl ether.

[0055] As component (C), commercially available products such as the Denacol series "EX-121", "EX-141", "EX-142-IM", "EX-145", "EX-146", "EX-192", "EX-810", "EX-811", "EX-850", "EX-850", "EX-851", "EX-821", "EX-830", "EX-832", "EX-841", "EX-211", "EX-212", "EX-214L", "EX-920", and "EX-931" manufactured by Nagase ChemteX Corporation can be used.

[0056] <Component (D): Epoxy Resin Curing Agent> Component (D) used in the present invention may be any curing agent capable of reacting with the epoxy groups in component (A) to thermoset the resin. Examples include amine-based curing agents, phenol-based curing agents, acid anhydride-based curing agents, hydrazide-based curing agents, and boron amine complexes. One or more of these may be used. From the viewpoint of improving the pot life of the thermosetting resin composition, component (D) preferably contains a boron amine complex. From the viewpoint of improving the pot life of the composition, the content of the boron amine complex in component (D) is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, and even more preferably 90% by mass or more, but not more than 100% by mass.

[0057] Examples of the boron amine complex include boron halide amine complexes, such as boron trifluoride amine complexes and boron trichloride amine complexes, and from the viewpoint of improving the pot life of the composition, preferably contains boron trichloride amine complexes.

[0058] Examples of the amine component in a boron amine complex such as a boron trichloride amine complex include alkylamines, alkanolamines, and alicyclic amines. Examples of alkylamines include monoalkylamines such as monoethylamine, monopropylamine, monobutylamine, monohexylamine, monooctylamine, and monolaurylamine; dialkylamines such as dimethylamine, diethylamine, dipropylamine, dibutylamine, dihexylamine, dioctylamine, and dilaurylamine; and trialkylamines such as triethylamine, tripropylamine, tributylamine, trihexylamine, trioctylamine, trilaurylamine, N,N-dimethylethylamine, N,N-dimethylpropylamine, N,N-dimethylbutylamine, N,N-dimethylhexylamine, N,N-dimethyloctylamine, and N,N-dimethyllaurylamine. Examples of alkanolamines include monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, N-methylethanolamine, N-methylisopropanolamine, N-butylethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, N-methyldiisopropanolamine, etc. Examples of cyclic aliphatic amines include piperidine, N,N-dicyclohexylmethylamine, etc.

[0059] Among the above, from the viewpoint of improving the pot life of the composition, the amine component in the boron amine complex such as the boron trichloride amine complex is preferably a trialkylamine, more preferably contains at least one selected from the group consisting of N,N-dimethylethylamine, N,N-dimethylpropylamine, N,N-dimethylbutylamine, N,N-dimethylhexylamine, N,N-dimethyloctylamine, and N,N-dimethyllaurylamine, and further preferably contains N,N-dimethyloctylamine.

[0060] As the boron amine complex used as component (D), commercially available products such as "Accelerator DY 9577" (boron trichloride amine complex, amine component: N,N-dimethyl-n-octylamine) manufactured by HUNTSMAN can be used.

[0061] Component (D) may also contain an epoxy resin curing agent other than a boron amine complex. Examples of epoxy resin curing agents other than a boron amine complex include amine-based curing agents, phenol-based curing agents, acid anhydride-based curing agents, and hydrazide-based curing agents, and one or more of these may be used. However, from the viewpoint of improving the pot life of the composition, the content of the epoxy resin curing agent other than a boron amine complex in component (D) is preferably 70% by mass or less, more preferably 50% by mass or less, even more preferably 30% by mass or less, still more preferably 20% by mass or less, still more preferably 10% by mass or less, and even more preferably 5% by mass or less, with the lower limit being 0% by mass.

[0062] <Component (E): Thermal Radical Polymerization Initiator> The component (E) used in the present invention may be any compound that generates radicals upon heating and can polymerize the (meth)acryloyloxy groups in the component (B), and examples thereof include azo compounds and organic peroxides.

[0063] Examples of the azo compound include azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (ABVN), 4,4'-azobis(4-cyanopentanoic acid) (ABCVA), 2,2'-azobis(2-methylbutyronitrile) (AMBN), 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH), 2,2'-azobis(2-methylpropionate) dimethyl, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, and the like, and one or more of these may be used.

[0064] Examples of organic peroxides include peroxyketals such as 2,2-bis(4,4-di-tert-butylperoxycyclohexyl)propane, 1,1-di(tert-hexylperoxy)cyclohexane, 1,1-di(tert-butylperoxy)cyclohexane, n-butyl-4,4-di(tert-butylperoxy)valerate, and 2,2-di(tert-butylperoxy)butane; hydroperoxides such as tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, and 1,1,3,3-tetramethylbutyl hydroperoxide; tert-butylcumyl peroxide, di-tert-butyl peroxide, di-tert-hexyl peroxide, dicumyl peroxide, α, Dialkyl peroxides such as α'-di(tert-butylperoxy)diisopropylbenzene, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3; diacyl peroxides such as diisobutyl peroxide, di(3,5,5-trimethylhexanol) peroxide, dilauroyl peroxide, disuccinic acid peroxide, and benzoyl peroxide; peroxydicarbonates such as diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, bis(4-tert-butylcyclohexyl)peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and di-sec-butyl peroxydicarbonate;Cumyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, tert-hexyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, tert-hexyl peroxy-2-ethylhexanoate, tert-butyl peroxy-2-ethylhexanoate, tert- Examples of peroxyesters include butyl peroxylaurate, tert-butylperoxy-3,5,5-trimethylhexanoate, tert-hexylperoxyisopropyl monocarbonate, tert-butylperoxyisopropyl monocarbonate, tert-butylperoxy-2-ethylhexyl monocarbonate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butyl peroxyacetate, tert-hexyl peroxybenzoate, and tert-butyl peroxybenzoate, and one or more of these can be used;

[0065] Among the above, from the viewpoint of improving the pot life of the composition, component (E) is preferably a thermal radical polymerization initiator having a 10-hour half-life temperature of 100° C. or higher, and more preferably an organic peroxide having a 10-hour half-life temperature of 100° C. or higher. Examples of organic peroxides having a 10-hour half-life temperature of 100° C. or higher include at least one selected from the group consisting of peroxyketals, hydroperoxides, dialkyl peroxides, and peroxyesters.

[0066] From the viewpoint of the curability of component (B) and improving the pot life of the composition, component (E) preferably contains a dialkyl peroxide, and more preferably contains 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0067] <Content> The content of component (A) in the thermosetting resin composition is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, even more preferably 40 to 60% by mass, and still more preferably 45 to 60% by mass, from the viewpoints of achieving low viscosity and a long pot life, and improving the Tg and elongation of the cured product.

[0068] The content of component (B) in the thermosetting resin composition is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, even more preferably 20 to 40% by mass, and still more preferably 25 to 35% by mass, from the viewpoints of achieving low viscosity and a long pot life, and improving the Tg and elongation of the cured product.

[0069] The content of component (B) in the thermosetting resin composition is preferably 10 to 80 parts by mass, more preferably 20 to 70 parts by mass, even more preferably 30 to 65 parts by mass, even more preferably 40 to 65 parts by mass, even more preferably 45 to 65 parts by mass, and even more preferably 50 to 60 parts by mass, per 100 parts by mass of component (A). When the content of component (B) in the thermosetting resin composition is 10 parts by mass or more per 100 parts by mass of component (A), low viscosity and a long pot life are easily achieved. When the content is 80 parts by mass or less, the Tg of the cured product is easily maintained.

[0070] The content of component (C) in the thermosetting resin composition is preferably 1 to 50% by mass, more preferably 3 to 40% by mass, even more preferably 5 to 30% by mass, still more preferably 7 to 25% by mass, and still more preferably 8 to 20% by mass, from the viewpoints of achieving low viscosity and a long pot life, and improving the Tg and elongation of the cured product.

[0071] The content of component (C) in the thermosetting resin composition is preferably 2 to 45 parts by mass, more preferably 3 to 40 parts by mass, even more preferably 5 to 30 parts by mass, and even more preferably 7 to 25 parts by mass, per 100 parts by mass of the total amount of components (A) to (C). When the content of component (C) in the thermosetting resin composition is 2 parts by mass or more per 100 parts by mass of the total amount of components (A) to (C), low viscosity and a long pot life are easily achieved. When the content is 45 parts by mass or less, the Tg of the cured product is easily maintained.

[0072] The content of component (D) in the thermosetting resin composition is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 20 parts by mass, even more preferably 1 to 10 parts by mass, and even more preferably 3 to 10 parts by mass, per 100 parts by mass of component (A). If the content of component (D) in the thermosetting resin composition is 0.1 part by mass or more per 100 parts by mass of component (A), curability is easily ensured, and if it is 40 parts by mass or less, a long pot life is easily achieved.

[0073] The content of component (E) in the thermosetting resin composition is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 4 parts by mass, even more preferably 0.5 to 3 parts by mass, and still more preferably 0.7 to 2 parts by mass, per 100 parts by mass of component (B). If the content of component (E) in the thermosetting resin composition is 0.01 part by mass or more per 100 parts by mass of component (B), curability is easily ensured, and if it is 5 parts by mass or less, a long pot life is easily achieved.

[0074] From the viewpoint of effectively exhibiting the effects of the present invention, the total content of components (A) to (E) in the thermosetting resin composition is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more, but 100% by mass or less, of the solid content of the thermosetting resin composition. Note that the "solid content of the thermosetting resin composition" refers to the amount obtained by excluding water and organic solvents from the total amount of the thermosetting resin composition.

[0075] <Other Components> The thermosetting resin composition may further contain other components, such as a modifying component such as a filler or a plasticizer, a flow adjusting component such as a thixotropic agent, a non-reactive diluent, a pigment, a leveling agent, a tackifier, or a stress relaxation component, depending on the application.

[0076] Among the above, examples of the stress relaxation component include elastomer particles such as silicone-based elastomer particles, butyl acrylate-based elastomer particles, polyetheramine-based elastomer particles, and other rubber particles. Liquid rubber components such as epoxidized polybutadiene can also be used. Commercially available stress relaxation components include Kane Ace B series, FM series, M series, and MX series manufactured by Kaneka Corporation, and liquid epoxidized polybutadienes such as Epolead PB3600 and Epolead PB4700 manufactured by Daicel Corporation. When the thermosetting resin composition contains a stress relaxation component, the content thereof is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass, of the solid content of the thermosetting resin composition.

[0077] <Solvent> The thermosetting resin composition of the present invention may further contain a solvent from the viewpoint of improving impregnation into reinforcing fibers. Examples of the solvent include alcohol-based solvents such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and 1-propoxy-2-propanol; ester-based solvents such as ethyl acetate and butyl acetate; ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ether-based solvents such as diethyl ether and diisopropyl ether; and hydrocarbon-based solvents such as toluene. One or more of these may be used. When the thermosetting resin composition contains a solvent, the content thereof is not particularly limited, but from the viewpoint of improving the impregnation ability into the reinforcing fibers, the content thereof in the thermosetting resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, and from the viewpoint of ease of removing the solvent, the content thereof is preferably 80% by mass or less, more preferably 70% by mass or less.

[0078] However, the thermosetting resin composition of the present invention is preferably a solventless composition that substantially does not contain a solvent. A solventless thermosetting resin composition is a thermosetting resin composition in which the solvent content in the thermosetting resin composition is preferably less than 5% by mass, more preferably 2% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and even more preferably 0% by mass. The thermosetting resin composition of the present invention is also preferably a non-aqueous thermosetting resin composition, and preferably has a low water content. The water content in the thermosetting resin composition is preferably less than 10% by mass, more preferably less than 5% by mass, even more preferably less than 2% by mass, even more preferably less than 1% by mass, even more preferably less than 0.1% by mass, and even more preferably 0% by mass. The water content here refers to the amount of water intentionally added to the thermosetting resin composition, and does not exclude the presence of a small amount of water as an impurity.

[0079] <Viscosity> The thermosetting resin composition of the present invention has a low viscosity. Specifically, the viscosity of the thermosetting resin composition at 25°C is preferably 1,500 mPa·s or less, more preferably 1,000 mPa·s or less, even more preferably 900 mPa·s or less, and still more preferably 800 mPa·s or less. Furthermore, the viscosity of the thermosetting resin composition at 25°C is preferably 50 mPa·s or more, more preferably 100 mPa·s or more. The viscosity of the thermosetting resin composition at 25°C can be measured using an E-type viscometer, specifically by the method described in the examples.

[0080] <Pot Life> The thermosetting resin composition of the present invention has a long pot life, and can achieve a pot life of, for example, 180 days or more when stored at room temperature (23°C).

[0081] There are no particular limitations on the method for preparing the thermosetting resin composition, and the composition can be prepared by mixing components (A) to (E) and other components used as needed using known methods and devices.

[0082] [Cured Product] The cured product of the thermosetting resin composition of the present invention (hereinafter simply referred to as the "cured product of the present invention") is obtained by thermally curing the above-described thermosetting resin composition of the present invention using a known method. The curing conditions for the thermosetting resin composition are appropriately selected depending on the application and form. The curing temperature is preferably 80 to 180°C, more preferably 100 to 160°C, and the curing time is preferably 1 minute to 12 hours, more preferably 5 minutes to 6 hours. The form of the cured product of the present invention is also not particularly limited and can be selected depending on the application. For example, when the thermosetting resin composition is used as a paint, the cured product of the composition is usually in the form of a film. From the viewpoint of effectively exerting the effects of the present invention, the cured product of the present invention is preferably a matrix resin for a fiber-reinforced composite material, as described below.

[0083] The glass transition temperature (Tg) of the cured product of the present invention is preferably 90° C. or higher, more preferably 95° C. or higher, and even more preferably 100° C. or higher, from the viewpoint of improving heat resistance when used as a matrix resin for a fiber-reinforced composite material, which will be described later, and is usually 200° C. or lower. Specifically, the Tg of the cured product can be measured by the method described in the Examples.

[0084] The tensile elongation of the cured product of the present invention is preferably 3.0% or more, more preferably 5.0% or more, and even more preferably 7.0% or more from the viewpoint of improving impact resistance when used as a matrix resin for a fiber-reinforced composite material, etc., as described below, and is preferably 20% or less, more preferably 10% or less from the viewpoint of obtaining high hardness. The tensile elongation of the cured product can be measured in accordance with JIS K7161-1:2014 and JIS K7161-2:2014, specifically by the method described in the Examples.

[0085] [Fiber-reinforced composite material] The fiber-reinforced composite material of the present invention (hereinafter also simply referred to as "composite material") comprises a cured product of the thermosetting resin composition and reinforcing fibers. By including the cured product of the thermosetting resin composition, the fiber-reinforced composite material of the present invention has high heat resistance and impact resistance due to the high glass transition temperature and elongation of the cured product.

[0086] Examples of the form of reinforcing fibers used in composite materials include short fibers, long fibers, and continuous fibers. Among these, from the viewpoint of producing large structures, long fibers or continuous fibers are preferred, and continuous fibers are more preferred. In this specification, short fibers refer to fibers having a fiber length of 0.1 mm or more and less than 10 mm, and long fibers refer to fibers having a fiber length of 10 mm or more and 100 mm or less. Furthermore, continuous fibers refer to fiber bundles having a fiber length of more than 100 mm.

[0087] Examples of the form of the continuous fiber include tow, sheet, tape, etc., and examples of the continuous fiber constituting the sheet or tape include unidirectional (UD) materials, woven fabrics, nonwoven fabrics, etc. The number of continuous fiber bundles (number of filaments) constituting the continuous fiber is preferably 3K to 50K, more preferably 6K to 40K, from the viewpoint of easily obtaining high strength and high elastic modulus.

[0088] In the case of continuous fibers, the average fiber length of the continuous fiber bundle is not particularly limited, but from the viewpoint of molding processability, it is preferably 1 to 10,000 m, more preferably 100 to 10,000 m. From the viewpoint of molding processability and the viewpoint that high strength and high elastic modulus can be easily obtained, the average fineness of the continuous fiber bundle is preferably 50 to 2,000 tex (g / 1,000 m), more preferably 200 to 1,500 tex, and even more preferably 500 to 1,500 tex. The average tensile elastic modulus of the continuous fiber bundle is preferably 50 to 1,000 GPa.

[0089] Examples of materials for the reinforcing fibers include inorganic fibers such as carbon fiber, glass fiber, basalt fiber, metal fiber, boron fiber, and ceramic fiber; and organic fibers such as aramid fiber, polyoxymethylene fiber, aromatic polyamide fiber, polyparaphenylene benzobisoxazole fiber, and ultra-high molecular weight polyethylene fiber. Among these, inorganic fibers are preferred from the viewpoint of achieving high strength. Because they are lightweight, have high strength, and have a high elastic modulus, at least one fiber selected from the group consisting of carbon fiber, glass fiber, and basalt fiber is preferred. From the viewpoint of strength and light weight, carbon fiber is more preferred. Examples of carbon fibers include polyacrylonitrile-based carbon fiber and pitch-based carbon fiber. Carbon fibers derived from plant-derived materials such as lignin and cellulose can also be used.

[0090] The reinforcing fibers may be treated with a treatment agent. Examples of the treatment agent include a surface treatment agent and a sizing agent. The surface treatment agent is preferably a silane coupling agent. Examples include a silane coupling agent having a vinyl group, a silane coupling agent having an amino group, a silane coupling agent having an epoxy group, a silane coupling agent having a (meth)acrylic group, and a silane coupling agent having a mercapto group.

[0091] Examples of the sizing agent include urethane-based sizing agents, epoxy-based sizing agents, acrylic-based sizing agents, polyester-based sizing agents, vinyl ester-based sizing agents, polyolefin-based sizing agents, polyether-based sizing agents, and carboxylic acid-based sizing agents, and these can be used alone or in combination of two or more. Examples of sizing agents that combine two or more types include urethane / epoxy-based sizing agents, urethane / acrylic-based sizing agents, and urethane / carboxylic acid-based sizing agents.

[0092] The amount of the treating agent is preferably 0.001 to 5% by mass, more preferably 0.1 to 3% by mass, and even more preferably 0.5 to 2% by mass relative to the reinforcing fiber, from the viewpoint of improving the interfacial adhesion between the thermosetting resin composition and the cured product and further improving the strength and impact resistance of the resulting fiber-reinforced composite material.

[0093] Commercially available products can also be used as reinforcing fibers. Commercially available continuous carbon fibers (tows) include, for example, the Torayca yarns "T300", "T300B", "T400HB", "T700SC", "T800SC", "T800HB", "T830HB", "T1000GB", "T100GC", "M35JB", "M40JB", "M46JB", "M50JB", "M55J", "M55JB", "M60JB", "M30SC", and "Z600" series manufactured by Toray Industries, Inc.; and Tenax "HTA40" series, "HTS40" series, "HTS45" series, and "HTS45P12" manufactured by Teijin Limited. series, "STS40" series, "UTS50" series, "ITS50" series, "ITS55" series, "IMS40" series, "IMS60" series, "IMS65" series, "IMS65P12" series, "HMA35" series, "UMS40" series, "UMS45" series, "UMS55" series, and "HTS40MC" series; carbon fiber tows of PYROFIL "HT", "IM", and "HM" series, GRAFIL "HT" series, and "DIALEAD" series manufactured by Mitsubishi Chemical Corporation; and the like.Commercially available continuous carbon fibers other than tow include Toray Industries, Inc.'s Torayca cloths "CO6142," "CO6151B," "CO6343," "CO6343B," "CO6347B," "CO6644B," "CK6244C," "CK6273C," "CK6261C," "UT70" series, "UM46" series, "BT70" series, "T300" series, "T300B" series, "T400HB" series, "T700SC" series, "T800SC" series, "T800HB" series, "T1000GB" series, "M35JB" series, and "M40 JB series, M46JB series, M50JB series, M55J series, M55JB series, M60JB series, M30SC series, and Z600GT series; carbon fiber fabrics such as PYROFIL "TR3110M", "TR3523M", "TR3524M", "TR6110HM", "TR6120HM", "TRK101M", "TRK510M", "TR3160TMS", "TRK979PQRW", "TRK976PQRW", "TR6185HM", and "TRK180M" manufactured by Mitsubishi Chemical Corporation; and the like.

[0094] <Content> From the viewpoint of obtaining high strength and high modulus of elasticity, the content of reinforcing fibers in the fiber reinforced composite is preferably in a range such that the volume fraction of the reinforcing fibers in the fiber reinforced composite is 0.10 or more, more preferably 0.20 or more, even more preferably 0.30 or more, and even more preferably 0.40 or more. From the viewpoint of improving impact resistance and moldability, the content is preferably 0.85 or less, more preferably 0.80 or less, and even more preferably 0.70 or less. The volume fraction Vf of the reinforcing fibers in the fiber reinforced composite can be calculated using the following formula: Vf = {mass (g) of reinforcing fibers / specific gravity of reinforcing fibers} ÷ [{mass (g) of reinforcing fibers / specific gravity of reinforcing fibers} + {mass (g) of cured product of thermosetting resin composition / specific gravity of cured product of thermosetting resin composition}]

[0095] <Method for producing fiber-reinforced composite material> The method for producing a fiber-reinforced composite material is not particularly limited, and any known method can be used as appropriate depending on the form of the reinforcing fibers, the size and shape of the composite material to be obtained, etc. Preferably, the composite material can be produced using a method similar to the method for producing a molded product described below.

[0096] [Molded Article] According to the present invention, a molded article containing the fiber-reinforced composite material can be provided. The molded article may be at least partially composed of the fiber-reinforced composite material. The shape and use of the molded article are not particularly limited, and may be, for example, a large structural material such as an automotive structural material or a building material. Furthermore, the molded article may be a hollow molded article such as a pipe, a shaft, a cylinder, or a tank.

[0097] [Method for producing a molded article containing a fiber-reinforced composite material] The present invention further provides a method for producing a molded article containing the fiber-reinforced composite material (hereinafter also simply referred to as the "method of the present invention"), the method comprising any one of a pultrusion method, a Va-RTM method, or a filament winding method. The thermosetting resin composition of the present invention used for producing a fiber-reinforced composite material has a low viscosity and a long pot life, and is therefore suitable for production methods including a pultrusion method, a Va-RTM method, or a filament winding method.

[0098] More specifically, the method of the present invention includes at least a step of impregnating a reinforcing fiber with a thermosetting resin composition (impregnation step) and a step of heat-curing the reinforcing fiber impregnated with the thermosetting resin composition (heating step).

[0099] The production of composites and molded articles using the pultrusion molding method can be carried out, for example, by the following procedure. First, reinforcing fibers unwound from a roll are immersed in a resin bath filled with the aforementioned thermosetting resin composition, impregnated with the composition, and then removed from the resin bath. Impregnation of the reinforcing fibers with the thermosetting resin composition can also be carried out under pressurized or reduced pressure as necessary. Subsequently, if necessary, a step of removing excess thermosetting resin composition using a squeeze roll or the like, a drying step to remove the solvent, and a degassing step may be carried out. The drying conditions in the drying step are not particularly limited, but are preferably conditions that allow for the removal of the solvent and do not excessively promote curing of the thermosetting resin composition. From this perspective, for example, the drying temperature can be selected in the range of 30 to 120°C, and the drying time can be selected in the range of 10 seconds to 5 minutes. Next, the reinforcing fibers impregnated with the thermosetting resin composition are introduced into a mold, heat-cured, and further pulled out using a pultrusion device to perform molding. The heat curing conditions are appropriately selected, but the curing temperature is preferably 80 to 180°C, more preferably 100 to 160°C, and the curing time is preferably 1 minute to 12 hours, more preferably 5 minutes to 6 hours.

[0100] The production of composites and molded articles using the Va-RTM method can be carried out, for example, by the following procedure. First, reinforcing fibers are placed in a pair of upper and lower molds, which are then sealed, and the pressure inside the molds is reduced. Next, a separately prepared thermosetting resin composition is injected into the molds to impregnate the reinforcing fibers, and the composition is then heated and cured to form the composite. The heat-curing conditions are the same as those described above.

[0101] Furthermore, the production of composites and molded articles by the filament winding molding method using tows as reinforcing fibers can be carried out, for example, by the following procedure. First, reinforcing fiber tows unwound from a roll are immersed in a resin bath filled with the above-mentioned thermosetting resin composition, and after impregnation with the composition, the tows are pulled out of the resin bath. The impregnation of the reinforcing fibers with the thermosetting resin composition can also be carried out under pressurized or reduced pressure conditions as necessary. Thereafter, the above-mentioned steps of removing excess thermosetting resin composition, drying, and degassing may be carried out as necessary. Next, the reinforcing fiber tows impregnated with the thermosetting resin composition are wound around the outer surface of a balloon, mandrel, or liner, and heated and cured to form a molded article. The heat curing conditions are the same as those described above.

[0102] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. Measurements and evaluations in the examples were carried out by the following methods.

[0103] <Viscosity> The viscosity (20°C) of the component (C) used in each example and the viscosity (25°C) of the thermosetting resin composition prepared in each example were measured at the respective predetermined temperatures using an E-type viscometer "TVE-22H type viscometer, cone-plate type" (manufactured by Toki Sangyo Co., Ltd.).

[0104] <Glass Transition Temperature (Tg)> The thermosetting resin composition prepared in each example was molded into a flat plate measuring 200 mm x 200 mm x 2 mm thick, and thermally cured in a hot air oven at 130°C for 180 minutes to produce a cured product. A strip measuring 50 mm x 10 mm x 2 mm thick was cut from the cured product to serve as a dynamic viscoelasticity (DMA) measurement sample. Using the sample, DMA bending measurement was performed under the following conditions using a rotational rheometer "ARES G2" (manufactured by TA Instruments). The peak top value of tan δ, plotted on the vertical axis and the measurement temperature on the horizontal axis, was taken as the Tg of the cured product. (Measurement Conditions) Measurement mode: bending DMA measurement Measurement temperature: 30 to 180°C Heating rate: 5°C / min

[0105] <Tensile elongation> The thermosetting resin composition prepared in each example was molded into a flat plate measuring 200 mm x 200 mm x 2 mm thick and thermally cured in a hot air oven at 130°C for 180 minutes to produce a cured product. A rectangular piece measuring 180 mm x 15 mm x 2 mm thick was cut from the cured product to serve as a tensile test specimen. Using the test specimen, a tensile test was performed under the following conditions (N = 3) in accordance with JIS K7161-1:2014 and JIS K7161-2:2014 using a precision universal testing machine ("Autograph AGX-plus" manufactured by Shimadzu Corporation), and the tensile elongation was calculated using the following formula. The length of the test specimen at break was calculated from the displacement of the load cell at break. (Measurement conditions) Distance between grippers: 115 mm Distance between gauge lines: 75 mm Load cell (tensile force): 1 kN Tensile speed: 1 mm / min (tensile direction: longitudinal direction of test piece) (Calculation formula) Tensile elongation (%) = (length of test piece at break - initial length of test piece) / (initial length of test piece) × 100

[0106] <Pot life> After measuring the initial viscosity at 23°C of the thermosetting resin composition prepared in each example, 10 g of the thermosetting resin composition was placed in a plastic cup (diameter 46 mm) and stored at 23°C. The time until the viscosity of the thermosetting resin composition became at least twice the initial viscosity was measured and is shown in Table 1. The viscosity of the thermosetting resin composition was measured using an E-type viscometer "TVE-22H cone-plate type viscometer" (manufactured by Toki Sangyo Co., Ltd.).

[0107] Examples 1 to 8 and Comparative Examples 1 to 4 (Preparation and Evaluation of Thermosetting Resin Compositions) The components shown in Table 1 were blended and mixed in the parts by mass shown in Table 1 to obtain thermosetting resin compositions. The obtained thermosetting resin compositions were evaluated by the methods described above. The results are shown in Table 1. The blend amounts (parts by mass) in Table 1 are all amounts of active ingredients.

[0108]

[0109] The components listed in Table 1 are as follows: <Epoxy resin (A)> Multifunctional epoxy resin having a glycidyloxy group derived from bisphenol A: "jER828" manufactured by Mitsubishi Chemical Corporation, liquid epoxy resin, epoxy equivalent: 186 g / equivalent, s = 0.11 in the following structural formula Multifunctional epoxy resin having a glycidyloxy group derived from bisphenol F: "jER807" manufactured by Mitsubishi Chemical Corporation, liquid epoxy resin, epoxy equivalent: 168 g / equivalent, t=0.09 in the following structural formula

[0110] <(Meth)acrylate Compound (B)> (B1) Poly(butadiene-co-acrylonitrile) terminated with methacryloyloxy groups at both ends, "Hypro1300X33LC" manufactured by Chori GLEX Co., Ltd. (B2) Ethoxylated bisphenol A dimethacrylate, k+l=approximately 10 in the following structural formula, "BPE-500" manufactured by Shin-Nakamura Chemical Co., Ltd.

[0111] <Reactive diluent (C)> Ethylene glycol diglycidyl ether, "Denacol EX-810" manufactured by Nagase ChemteX Corporation, epoxy equivalent: 113 g / equivalent, viscosity at 20°C: 20 mPa·s Neopentyl glycol diglycidyl ether, "Denacol EX-211" manufactured by Nagase ChemteX Corporation, epoxy equivalent: 138 g / equivalent, viscosity at 20°C: 20 mPa·s

[0112] <Epoxy resin curing agent (D)> Boron trichloride amine complex (amine component: N,N-dimethyl-n-octylamine), "Accelerator DY 9577" manufactured by HUNTSMAN

[0113] <Thermal radical polymerization initiator (E)> 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, "Perhexa 25B" manufactured by NOF Corporation, 10-hour half-life temperature: 117.9°C

[0114] Table 1 shows that the thermosetting resin compositions of the present invention have a viscosity of 1,000 mPa·s or less at 25°C and a long pot life. Furthermore, the cured products achieved a glass transition temperature of 90°C or higher and a tensile elongation of 3.0% or higher. In contrast, the cured products of the thermosetting resin compositions of Comparative Examples 1 and 2, which did not contain component (B) or component (E) (thermal radical polymerization components), had low tensile elongation, and the thermosetting resin compositions of Comparative Examples 3 and 4, which did not contain component (C), showed a significantly increased viscosity (initial viscosity) at 25°C.

[0115] According to the present invention, it is possible to provide a thermosetting resin composition that has a low viscosity and a long pot life and that can give a cured product with a high glass transition temperature and elongation; a cured product thereof; a fiber-reinforced composite material containing the cured product and reinforcing fibers; and a method for producing a molded article containing the fiber-reinforced composite material.

Claims

1. A thermosetting resin composition comprising: component (A): an epoxy resin not containing a polybutadiene structure; component (B): a (meth)acrylate compound; component (C): a reactive diluent; component (D): an epoxy resin curing agent; and component (E): a thermal radical polymerization initiator.

2. The thermosetting resin composition according to claim 1, wherein the viscosity of said component (C) at 20°C is 200 mPa·s or less.

3. The thermosetting resin composition according to claim 1 or 2, wherein the content of said component (C) in said thermosetting resin composition is 1 to 50 mass %.

4. A thermosetting resin composition according to any one of claims 1 to 3, wherein the component (B) comprises component (B1): poly(butadiene-co-acrylonitrile) having (meth)acryloyloxy groups at both ends.

5. The thermosetting resin composition according to any one of claims 1 to 4, wherein the component (B) comprises component (B2): a polyfunctional (meth)acrylate having an aromatic ring.

6. The thermosetting resin composition according to any one of claims 1 to 5, wherein the component (C) contains a compound having two or more glycidyl groups.

7. The thermosetting resin composition according to any one of claims 1 to 6, wherein component (D) comprises a boron amine complex.

8. The thermosetting resin composition according to claim 7, wherein the amine component in the boron amine complex is a trialkylamine.

9. The thermosetting resin composition according to any one of claims 1 to 8, wherein the viscosity of the thermosetting resin composition at 25°C is 1,000 mPa·s or less.

10. A cured product of the thermosetting resin composition according to any one of claims 1 to 9.

11. A fiber-reinforced composite material comprising the cured product according to claim 10 and reinforcing fibers.

12. The fiber-reinforced composite material according to claim 11, wherein the reinforcing fibers are at least one selected from the group consisting of carbon fibers, glass fibers, and basalt fibers.

13. A method for producing a molded article containing the fiber-reinforced composite material according to claim 11 or 12, the method comprising any one of a pultrusion method, a Va-RTM method, or a filament winding molding method.

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