Thermosetting resin composition, cured product of same, prepreg, fiber-reinforced composite material, and high-pressure gas container

Abstract

Disclosed are: a thermosetting resin composition which contains an epoxy resin (component (A)), a (meth)acrylate compound (component (B)), an epoxy resin curing agent (component (C)) and a thermal radical polymerization initiator (component (D)), wherein the component (B) contains a poly(butadiene-CO-acrylonitrile) having acryloyloxy groups at both ends (component (B1)) and a multifunctional (meth)acrylate (component (B2)) other than the component (B1), and the component (C) contains a boron amine complex; a cured product of this thermosetting resin composition; a prepreg; a fiber-reinforced composite material; and a high-pressure gas container which comprises this fiber-reinforced composite material.

Description

Thermosetting resin compositions and their cured products, prepregs, fiber-reinforced composite materials, and high-pressure gas cylinders

[0001] The present invention relates to a thermosetting resin composition and a cured product thereof, a prepreg, a fiber-reinforced composite material, and a high-pressure gas container containing the fiber-reinforced composite material.

[0002] In recent years, environmentally friendly natural gas vehicles (CNG vehicles) and fuel cell vehicles (FCVs) have become increasingly popular. Fuel cell vehicles are powered by fuel cells, making it essential to develop hydrogen stations where hydrogen, the fuel used for fueling these vehicles, is compressed to high pressure and filled into the vehicles. Until now, steel tanks have been used as high-pressure gas storage tanks at hydrogen stations for fuel cell vehicles, or as on-board fuel tanks for CNG vehicles and fuel cell vehicles. However, progress has been made in the development of lighter high-pressure gas storage tanks that use resin materials for the tank liner or outer layer. Reducing the weight of on-board fuel tanks has the advantage of improving the fuel efficiency of vehicles equipped with them.

[0003] Pressure vessels such as high-pressure gas storage tanks typically have a metal liner and an outer layer that covers the outer surface of the liner. However, in recent years, in order to produce lighter pressure vessels, the production of pressure vessels with plastic liners and linerless pressure vessels has also been considered.

[0004] A known method for producing a pressure vessel is to manufacture the pressure vessel by filament winding molding using a tow prepreg (also called a towpreg), in which reinforcing fibers are pre-impregnated with an epoxy resin composition.

[0005] 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.

[0006] Japanese Patent No. 6993549 Japanese Patent Application Laid-Open No. 2022-27815

[0007] The thermosetting resin composition used as the matrix resin of the prepreg is required to have a long pot life to ensure the long-term storage stability of the prepreg. Furthermore, in order to ensure heat resistance and high toughness in the fiber-reinforced composite material obtained by curing the prepreg, the thermosetting resin composition used as the matrix resin of the prepreg is required to have both a high glass transition temperature and a high elongation percentage in the cured product. However, the techniques disclosed in Patent Documents 1 and 2 have difficulty in satisfying all of these required properties.

[0008] An object of the present invention is to provide a thermosetting resin composition which gives a cured product having a high glass transition temperature and elongation and which has a long pot life; a cured product thereof, a prepreg, a fiber-reinforced composite material; and a high-pressure gas container containing the fiber-reinforced composite material.

[0009] The present inventors have discovered that the above-mentioned problems can be solved by using a specific (meth)acrylate compound and epoxy resin curing agent in a thermosetting resin composition containing an epoxy resin, a (meth)acrylate compound, 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, component (B): a (meth)acrylate compound, component (C): an epoxy resin curing agent, and component (D): a thermal radical polymerization initiator, wherein component (B) contains poly(butadiene-co-acrylonitrile) (B1) having acryloyloxy groups at both ends and a polyfunctional (meth)acrylate (B2) other than component (B1), and component (C) contains a boron amine complex. [2] The thermosetting resin composition according to item [1] above, wherein component (B2) contains a polyfunctional (meth)acrylate containing an aromatic ring. [3] The thermosetting resin composition according to [1] or [2] above, wherein the content of component (B) is 5 to 50 parts by mass per 100 parts by mass of component (A) in the thermosetting resin composition. [4] The thermosetting resin composition according to any one of [1] to [3] above, wherein the content of component (B1) in component (B) is 1 to 70% by mass. [5] The thermosetting resin composition according to any one of [1] to [4] above, wherein the boron amine complex is a boron trichloride amine complex. [6] The thermosetting resin composition according to any one of [1] to [5] above, wherein the amine component in the boron amine complex is a trialkylamine. [7] A cured product of the thermosetting resin composition according to any one of [1] to [6] above. [8] A prepreg comprising the thermosetting resin composition according to any one of [1] to [6] above and reinforcing fibers. [9] The prepreg according to the above item [8], wherein the prepreg is a tow prepreg.

[10] A fiber-reinforced composite material obtained by curing the prepreg according to the above item [8] or [9].

[11] A high-pressure gas container comprising the fiber-reinforced composite material according to the above item

[10] .

[0010] According to the present invention, it is possible to provide a thermosetting resin composition which gives a cured product having a high glass transition temperature and elongation and which has a long pot life, a cured product thereof, a prepreg, a fiber-reinforced composite material, and a high-pressure gas container containing the fiber-reinforced composite material. The high-pressure gas container can be produced by filament winding molding using the prepreg of the present invention, and it is also possible to produce a high-pressure gas container with a plastic liner or a linerless high-pressure gas container.

[0011] [Definitions] In this specification, "(meth)acrylate" includes both acrylate and methacrylate. In this specification, "room temperature" means 25°C unless otherwise specified.

[0012] [Thermosetting Resin Composition] The thermosetting resin composition of the present invention (hereinafter also referred to as "the composition of the present invention") is a thermosetting resin composition containing: component (A): an epoxy resin; component (B): a (meth)acrylate compound; component (C): an epoxy resin curing agent; and component (D): a thermal radical polymerization initiator, wherein component (B) contains poly(butadiene-co-acrylonitrile) (B1) having acryloyloxy groups at both ends and a polyfunctional (meth)acrylate (B2) other than component (B1), and component (C) contains a boron amine complex. The composition of the present invention has the above-mentioned configuration, thereby enabling the production of a cured product having a high glass transition temperature (Tg) and elongation, and further having a long pot life.

[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) and a (meth)acrylate compound (B) as thermosetting resins. The epoxy resin curing agent (C) is a curing agent for the epoxy resin (A), and the thermal radical polymerization initiator (D) acts as a thermal radical polymerization initiator for curing the (meth)acrylate compound (B). Thermosetting (epoxy) resin compositions comprising an epoxy resin and an epoxy resin curing agent generally have excellent curability, heat resistance, etc., but the low elongation of the cured product has been a problem for use in high-pressure gas containers and the like, which require high toughness. Furthermore, because epoxy resin compositions usually cure quickly, an improvement in pot life has also been necessary, particularly for use in prepregs stored at room temperature. The inclusion of a boron amine complex in component (C) used in the thermosetting resin composition of the present invention improves pot life. Furthermore, by forming the composition of the present invention into a hybrid of an epoxy resin curing system of component (A)-component (C) and a (meth)acrylate curing system of component (B)-component (D), the probability of contact between component (A) and component (C) in the composition is reduced, which is believed to further improve pot life. Furthermore, component (B) used in the present invention contains poly(butadiene-co-acrylonitrile) (B1) terminated with acryloyloxy groups at both ends and a polyfunctional (meth)acrylate (B2) other than component (B1). The inclusion of component (B1), a specific diacrylate having a rubber structure, in component (B) is believed to improve the elongation of the cured product, and the inclusion of component (B2) in component (B) is believed to have suppressed an excessive decrease in the Tg of the cured product caused by the use of component (B1).

[0014] <Component (A): Epoxy Resin> The epoxy resin (A) used in the present invention is not particularly limited as long as it is a polyfunctional epoxy resin having two or more epoxy groups. From the viewpoint of improving the Tg of the cured product, however, a polyfunctional epoxy resin containing an aromatic ring or an alicyclic structure in the molecule is preferred.

[0015] Specific examples of the epoxy resin (A) include at least one selected from the group consisting of epoxy resins having a glycidylamino group derived from meta-xylylenediamine, epoxy resins having a glycidylamino group derived from para-xylylenediamine, epoxy resins having a glycidylamino group derived from 1,3-bis(aminomethyl)cyclohexane, epoxy resins having a glycidylamino group derived from 1,4-bis(aminomethyl)cyclohexane, epoxy resins having a glycidylamino group derived from diaminodiphenylmethane, epoxy resins having a glycidylamino group and / or a glycidyloxy group derived from para-aminophenol, epoxy resins having a glycidyloxy group derived from resorcinol, epoxy resins having a glycidyloxy group derived from bisphenol A, epoxy resins having a glycidyloxy group derived from bisphenol F, and epoxy resins having a glycidyloxy group derived from phenol novolac. One or more of the above epoxy resins can be used.

[0016] 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 epoxy resins having a glycidylamino group derived from meta-xylylenediamine, epoxy resins having a glycidylamino group derived from para-xylylenediamine, epoxy resins having a glycidyloxy group derived from bisphenol A, and epoxy resins having a glycidyloxy group derived from bisphenol F, and more preferably one whose main component is at least one selected from the group consisting of epoxy resins having a glycidyloxy group derived from bisphenol A and epoxy resins having a glycidyloxy group derived from bisphenol F. Here, the term "main component" means that other components may be contained within the scope of the present invention, and preferably means 50 to 100 mass%, more preferably 70 to 100 mass%, and even more preferably 90 to 100 mass% of the total.

[0017] The epoxy resin (A) may be either a solid epoxy resin or a liquid epoxy resin, but from the viewpoint of facilitating impregnation into reinforcing fibers when applied to prepregs, it is preferable that the epoxy resin (A) contains a liquid epoxy resin as its main component. A "solid epoxy resin" refers to an epoxy resin that does not have fluidity at 25°C, and a "liquid epoxy resin" refers to an epoxy resin that has fluidity at 25°C.

[0018] The epoxy equivalent (functional group equivalent) of the epoxy resin (A) is not particularly limited, but from the viewpoint of facilitating impregnation into reinforcing fibers when applied to prepregs, it is preferably 1,500 g / eq or less, more preferably 1,200 g / eq or less, even more preferably 1,000 g / eq or less, still more preferably 800 g / eq or less, even more preferably 500 g / eq or less, more preferably 300 g / eq or less, even more preferably 250 g / eq or less, still more preferably 220 g / eq or less, and even more preferably 200 g / eq or less, and from the viewpoint of curing property, it is preferably 120 g / eq 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.

[0019] <Component (B): (Meth)acrylate Compound> The (meth)acrylate compound (B) used in the present invention includes poly(butadiene-co-acrylonitrile) (B1) having acryloyloxy groups at both ends thereof, and a polyfunctional (meth)acrylate (B2) other than component (B1).

[0020] (Poly(butadiene-co-acrylonitrile) (B1) with Acryloyloxy Groups at Both Ends) Component (B1) used in the present invention is a diacrylate containing a copolymer structure of butadiene and acrylonitrile and having acryloyloxy groups at both ends of the main chain. 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 mass%, more preferably 10 to 30 mass%, and even more preferably 10 to 25 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 of component (B1) include "Hypro 1300X33LC" manufactured by Chori GLEX.

[0021] 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%, and even more preferably 15 to 50 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 and reduce variation in the physical properties of the cured product.

[0022] (Polyfunctional (meth)acrylate (B2) other than component (B1)) Component (B2) used in the present invention may be any (meth)acrylate other than component (B1) that has two or more (meth)acrylic groups. Component (B2) is preferably a (meth)acrylate that does not have a glycidyl group. Examples of (meth)acrylates other than component (B1) include epoxy (meth)acrylates having a main skeleton derived from an epoxy compound, urethane (meth)acrylates having a main skeleton derived from a polyisocyanate and a polyol, and polyester (meth)acrylates having a main skeleton derived from a polyol. Among these, at least one selected from the group consisting of urethane (meth)acrylates and polyester (meth)acrylates is preferred from the viewpoint of improving the Tg and elongation of the cured product.

[0023] The number of (meth)acrylic groups in component (B2) is preferably 2 to 6, more preferably 2 to 4, even more preferably 2 to 3, and even more preferably 2. When the number of (meth)acrylic groups in component (B2) is 2 or more, this tends to contribute to an improvement in the Tg of the cured product, while when the number is 6 or less, the elongation of the cured product can be maintained.

[0024] From the viewpoint of improving the Tg of the cured product, it is preferable that component (B2) contains a polyfunctional (meth)acrylate containing an aromatic ring. The aromatic ring 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 preferable, and a benzene ring is more preferable. The number of aromatic rings contained in component (B2) may be one or more, and from the viewpoint of improving the Tg of the cured product, it is preferably two or more.

[0025] Specific examples of the polyfunctional (meth)acrylate containing an aromatic ring used as component (B2) include di(meth)acrylates having a structure derived from biphenol, di(meth)acrylates having a structure derived from bisphenol A, di(meth)acrylates having a structure derived from bisphenol F, di(meth)acrylates having a fluorene structure, and di(meth)acrylates having a structure derived from an aromatic hydrocarbon formaldehyde resin, and one or more of these can be used. The di(meth)acrylate may be any of epoxy di(meth)acrylate, urethane di(meth)acrylate, and polyester di(meth)acrylate.

[0026] 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."

[0027] From the viewpoint of improving the Tg and elongation of the cured product, the aromatic ring-containing polyfunctional (meth)acrylate used as component (B2) is more preferably at least one selected from the group consisting of compounds represented by the following general formula (B2-1), compounds represented by the following general formula (B2-2), and di(meth)acrylates having a structure derived from an aromatic hydrocarbon-formaldehyde resin: In the formula, R １ and R ２ each independently represents a hydrogen atom or a methyl group, R ３ and R４ each independently represents a hydrogen atom or a methyl group, m and n represent the number of repeating units, and each independently represents a number from 0 to 20. In the formula, R １ and R ２ is the same as above, and R ５ is 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.

[0028] 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 further improving the Tg and elongation of the cured product, m and n in 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, m+n is a number of 0 to 40, and from the viewpoint of further improving the Tg and elongation of the cured product, is a number of preferably 2 to 30, more preferably 2 to 20, and even more preferably 4 to 12.

[0029] In the general formula (B2-2), R １ and R ２ is preferably a methyl group. ５ is 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.

[0030] X in the general formula (B2-2) 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.

[0031] When Y in the general formula (B2-2) does not contain an aromatic ring, the diisocyanate is a diisocyanate that contains an aromatic ring. When Y in the general formula (B2-2) contains an aromatic ring, the diisocyanate is, from the viewpoint of improving the elongation of the cured product, preferably at least one selected from the group consisting of linear 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.

[0032] In the general formula (B2-2), 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.

[0033] 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.

[0034] Y in the general formula (B2-2) 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.

[0035] In the general formula (B2-2), r is a number of 1 or more, and preferably a number of 1 or more and 200 or less.

[0036] Furthermore, examples of commercially available di(meth)acrylates having a structure derived from aromatic hydrocarbon formaldehyde resins, which are used as component (B2), include "NIKANOL XUAT" (urethane acrylate xylene resin) manufactured by Fudow Co., Ltd.

[0037] From the viewpoint of improving the Tg of the cured product, the content of the aromatic ring-containing polyfunctional (meth)acrylate in component (B2) 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 100% by mass or less.

[0038] As component (B2), polyfunctional (meth)acrylates containing no aromatic ring, such as α,ω-alkanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate, can also be used.

[0039] The content of component (B2) in component (B) is preferably 30 to 99 mass%, more preferably 40 to 95 mass%, even more preferably 40 to 90 mass%, still more preferably 40 to 85 mass%, and even more preferably 50 to 85 mass%. If the content of component (B2) in component (B) is 30 mass% or more, it is likely to contribute to an improvement in the Tg of the cured product, while if it is 99 mass% or less, it is possible to maintain the elongation of the cured product and reduce variation in the physical properties of the cured product.

[0040] In addition to components (B1) and (B2), component (B) may also contain a (meth)acrylate other than components (B1) and (B2), such as a monofunctional (meth)acrylate, for the purpose of lowering the viscosity of the composition, etc. However, from the viewpoint of improving the Tg 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, and even more preferably 90% by mass or more, but 100% by mass or less.

[0041] The content of component (B) in the thermosetting resin composition is preferably 5 to 50 parts by mass, more preferably 5 to 45 parts by mass, and even more preferably 10 to 45 parts by mass, per 100 parts by mass of component (A). When the content of component (B) in the thermosetting resin composition is 5 parts by mass or more per 100 parts by mass of component (A), a long pot life is easily achieved, and when it is 50 parts by mass or less, the Tg of the cured product is easily maintained.

[0042] <Epoxy Resin Curing Agent (C)> The epoxy resin curing agent (C) used in the present invention contains a boron amine complex from the viewpoint of achieving a long pot life. From the viewpoint of achieving a long pot life, the content of the boron amine complex in component (C) 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 still more preferably 90% by mass or more, but 100% by mass or less.

[0043] 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 achieving a long pot life, boron trichloride amine complexes are preferred.

[0044] Examples of the amine component in the boron amine complex include alkylamines, alkanolamines, and cyclic aliphatic 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.

[0045] Among the above, from the viewpoint of achieving a long pot life, the amine component in the boron amine complex is preferably a tertiary alkylated amine, i.e., a trialkylamine, more preferably 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 even more preferably N,N-dimethyloctylamine.

[0046] Commercially available boron amine complexes used as component (C) include "Accelerator DY 9577" (boron trichloride amine complex, amine component: N,N-dimethyl-n-octylamine) manufactured by HUNTSMAN.

[0047] Component (C) 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 achieving a long pot life, the content of the epoxy resin curing agent other than a boron amine complex in component (C) 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.

[0048] The content of component (C) in the thermosetting resin composition is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of component (A). When the content of component (C) 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 when it is 40 parts by mass or less, a long pot life is easily achieved.

[0049] <Component (D): Thermal Radical Polymerization Initiator> The component (D) used in the present invention may be any compound that generates radicals upon heating and can cure the component (B), and examples thereof include azo compounds and organic peroxides.

[0050] 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.

[0051] 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; and ter Dialkyl peroxides such as t-butylcumyl peroxide, di-tert-butyl peroxide, and di-tert-hexyl peroxide; 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-butyl peroxylaurate, tert-butylperoxy-3,5,5-trimethylhexanoate, tert-hexylperoxyisopropyl monocarbonate peroxyesters such as tert-butylperoxyisopropyl monocarbonate, tert-butylperoxy-2-ethylhexyl monocarbonate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butylperoxyacetate, tert-hexylperoxybenzoate, and tert-butylperoxybenzoate; and dialkyl peroxides such as dicumyl peroxide, α,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, and one or more of these can be used;

[0052] Among the above, from the viewpoint of the curability of component (B) and achieving a long pot life of the composition when stored at room temperature, organic peroxides are preferred as component (D), and at least one selected from the group consisting of peroxyketals, hydroperoxides, diacyl peroxides, peroxydicarbonates, peroxyesters, and dialkyl peroxides is more preferred, dialkyl peroxides are even more preferred, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane is even more preferred.

[0053] The content of component (D) in the thermosetting resin composition is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 2 parts by mass, even more preferably 0.1 to 2 parts by mass, and still more preferably 0.5 to 2 parts by mass, per 100 parts by mass of component (B). If the content of component (D) 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.

[0054] <Component (E): Crushed Natural Silica Stone> The thermosetting resin composition can further contain crushed natural silica stone as component (E). When the thermosetting resin composition contains component (E), it is possible to improve the hardness of the resulting cured product while suppressing a decrease in elongation. Natural silica stone is a general term for natural siliceous rocks produced in Japan and around the world, and examples thereof include SiO ２ and quartz sand containing impurities such as Al and Fe. The natural silica stone pulverized material is obtained by finely pulverizing the natural silica stone. From the viewpoint of improving the hardness of the resulting cured product, the D50 of component (E) measured by laser scattering / diffraction method is preferably 0.5 to 10 μm, and the uniformity coefficient K expressed as D60 / D10 is preferably 2 to 8.

[0055] When the thermosetting resin composition contains component (E), the content of component (E) in the thermosetting resin composition is preferably 0.01 to 10 mass%, more preferably 0.05 to 5.0 mass%, and even more preferably 0.1 to 3.0 mass%. When the content of component (E) in the thermosetting resin composition is 0.01 mass% or more, it contributes to improving the hardness of the resulting cured product, and when it is 10 mass% or less, it is possible to improve the hardness while suppressing a decrease in the elongation of the cured product. Note that the content of component (E) includes not only the ground natural silica stone intentionally blended into the thermosetting resin composition, but also the ground natural silica stone derived from the raw materials of the composition or mixed in during the production process of the composition.

[0056] <Other Components> The thermosetting resin composition may further contain other components depending on the application, such as a modifying component such as a filler or a plasticizer, a flow adjusting component such as a thixotropic agent, a reactive or non-reactive diluent, a pigment, a leveling agent, a tackifier, or a stress relaxation component.

[0057] 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 Evoraid PB3600 and Evoraid PB4700 manufactured by Daicel Corporation. When the thermosetting resin composition contains a stress relaxation component, the content of the component 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. The "solid content of the thermosetting resin composition" refers to the total amount of the thermosetting resin composition excluding water and organic solvents.

[0058] <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. From the viewpoint of the solubility of the blended components and the ease of removing the solvent, the solvent is preferably at least one selected from the group consisting of alcohol-based solvents, ester-based solvents, ketone-based solvents, and hydrocarbon-based solvents having 8 or less carbon atoms, and more preferably at least one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, and toluene.

[0059] From the viewpoint of effectively exhibiting the effects of the present invention, the total content of the components (A) to (D) 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.

[0060] When the thermosetting resin composition contains a solvent, its content is not particularly limited, but from the viewpoint of improving the impregnation into the reinforcing fibers, it is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more in the thermosetting resin composition, and from the viewpoint of ease of solvent removal, it is preferably 80% by mass or less, more preferably 70% by mass or less. The thermosetting resin composition may be a solvent-free composition that does not substantially contain a solvent. A solvent-free thermosetting resin composition is one 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.

[0061] There are no particular limitations on the method for preparing the thermosetting resin composition, and the thermosetting resin composition can be prepared by mixing components (A) to (D) and other components used as needed using known methods and equipment. There are also no particular limitations on the order in which the components contained in the thermosetting resin composition are mixed. However, when components (A) and (B) have high viscosity, it is preferable to first heat and mix components (A) and (B) at 80 to 120°C, then cool to below 80°C, and then mix components (C) and (D). This is to prevent thermal polymerization of component (C) from progressing during the preparation of the thermosetting resin composition.

[0062] [Cured Product] The cured product of the thermosetting resin composition of the present invention (hereinafter also simply referred to as "the cured product of the present invention") is obtained by thermally curing the above-mentioned thermosetting resin composition of the present invention by a known method. The curing conditions for the thermosetting resin composition are selected appropriately depending on the application and form, but the curing temperature is preferably 90 to 160°C, more preferably 100 to 150°C. 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 described below.

[0063] From the viewpoint of use as a matrix resin for a fiber-reinforced composite material described below, as well as in high-pressure gas containers and the like, the glass transition temperature (Tg) of the cured product of the present invention is preferably 80° C. or higher, more preferably 85° C. or higher, even more preferably 87° C. or higher, and still more preferably 90° C. or higher, and is usually 200° C. or lower. Specifically, the Tg of the cured product can be measured by the method described in the Examples.

[0064] [Prepreg] The prepreg of the present invention contains the thermosetting resin composition and reinforcing fibers. Examples of the reinforcing fibers used in the prepreg include short fibers, long fibers, and continuous fibers. Among these, from the viewpoint of using the resulting prepreg as a material for constructing a high-pressure gas container, which will be described later, long fibers or continuous fibers are preferred, and continuous fibers are more preferred. In this specification, short fibers refer to fibers having a length of 0.1 mm or more but less than 10 mm, and long fibers refer to fibers having a length of 10 mm or more but 100 mm or less. Furthermore, continuous fibers refer to fiber bundles having a fiber length of more than 100 mm.

[0065] Examples of the shape 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. From the viewpoint of producing high-pressure gas containers using prepregs by filament winding or tape winding, the shape of the continuous fiber is preferably tow or tape, and more preferably tow. The number of continuous fiber bundles constituting the tow (number of filaments) is preferably 3K to 50K, more preferably 6K to 40K, from the viewpoint of easily obtaining high strength and high elastic modulus.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] The amount of the treatment 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 with the cured product of the thermosetting resin composition and further improving the strength and impact resistance of the obtained prepreg and composite material.

[0071] 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.

[0072] The content of the reinforcing fibers in the prepreg is preferably in a range such that the volume fraction of the reinforcing fibers in the prepreg 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 obtaining high strength and high elastic modulus. Also, from the viewpoint of gas barrier properties, impact resistance, and moldability, the volume fraction of the reinforcing fibers in the prepreg is preferably 0.85 or less, more preferably 0.80 or less, and even more preferably 0.70 or less. １ can be calculated from the following formula: １ = {mass (g) of reinforcing fiber / specific gravity of reinforcing fiber} ÷ [{mass (g) of reinforcing fiber / specific gravity of reinforcing fiber} + {mass (g) of solid content of impregnated thermosetting resin composition / specific gravity of solid content of thermosetting resin composition}]

[0073] Furthermore, from the viewpoint of obtaining the effects of the present invention, the total content of the solids of the thermosetting resin composition constituting the prepreg and the reinforcing fibers is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, with the upper limit being 100% by mass.

[0074] <Shape of prepreg and manufacturing method> The shape of the prepreg varies depending on the form of the reinforcing fibers used, but from the viewpoint of manufacturing high-pressure gas containers by the filament winding method, tow prepreg is preferred. In addition, when continuous fibers in the form of unidirectional (UD) material, woven fabric, nonwoven fabric, etc. are used, tape-shaped or sheet-shaped prepreg can also be used. Among these, from the viewpoint of manufacturing high-pressure gas containers by the tape winding method, tape-shaped prepreg is preferred, and UD tape is more preferred.

[0075] The method for producing the prepreg is not particularly limited, and the prepreg can be produced according to a conventional method. For example, the prepreg can be obtained by impregnating the reinforcing fibers with the thermosetting resin composition, and then optionally subjecting the resultant to a drying step to remove the solvent.

[0076] The method for impregnating the reinforcing fibers with the thermosetting resin composition is not particularly limited, and any known method can be used as appropriate depending on the shape of the reinforcing fibers, etc. For example, when producing a tow prepreg, a method can be used in which a continuous fiber bundle unwound from a roll is immersed in a resin bath filled with the above-mentioned thermosetting resin composition, and after impregnation with the composition, the bundle is pulled out of the resin bath. A step of removing excess thermosetting resin composition using a squeeze roll or the like can then be performed. The impregnation with the thermosetting resin composition can also be performed under pressurized or reduced pressure as necessary.

[0077] Next, if necessary, the reinforcing fibers impregnated with the thermosetting resin composition are subjected to a drying process to remove the solvent. The drying conditions in the drying process are not particularly limited, but are preferably conditions that allow the solvent to be removed and do not cause excessive 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.

[0078] The prepreg obtained through the drying step may be wound up or the like to form a prepreg product, or it may be subjected to the drying step without being wound up or the like and then continuously supplied to the production of a fiber-reinforced composite material.

[0079] [Fiber-reinforced composite material] The fiber-reinforced composite material of the present invention (hereinafter also simply referred to as "composite material") is obtained by curing the prepreg, and contains a cured product of the thermosetting resin composition and reinforcing fibers. By containing the cured product of the thermosetting resin composition, the fiber-reinforced composite material of the present invention has high heat resistance and impact resistance. The prepreg, thermosetting resin composition, reinforcing fibers, and preferred embodiments thereof used in producing the composite material are the same as those described above.

[0080] <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 gas barrier properties, 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}]

[0081] <Method for Producing Fiber-Reinforced Composite Material> A composite material can be produced by pre-molding the prepreg into a desired shape and then curing the prepreg. For example, when the composite material of the present invention is applied to a hollow molded article such as a pipe, shaft, cylinder, or tank, a tow- or tape-shaped prepreg can be molded by a filament winding method, tape winding method, braiding method, 3D printer method, or the like to produce the composite material. In the filament winding method or tape winding method, specifically, a tow- or tape-shaped prepreg is wound around the outer surface of a balloon, mandrel, or liner, and then heat-cured to produce a composite material of a desired shape. In the braiding method, for example, a tow- or tape-shaped prepreg is braided with a braider using a balloon or mandrel to form a unidirectional or braided structure, and then the prepreg is heat-cured. Note that the braiding method can also be used to braid and mold a tow- or tape-shaped prepreg without using a balloon or mandrel.

[0082] When using a sheet-shaped prepreg using unidirectional (UD) material, woven fabric, nonwoven fabric, or the like as continuous fibers, a composite material can be produced by placing one or more prepregs in a mold and heating and curing them under vacuum or pressurized conditions.

[0083] The method for curing the prepreg in the production of the composite material is not particularly limited, and is carried out by a known method at a temperature and for a time sufficient to cure the thermosetting resin composition contained in the prepreg. The prepreg curing conditions depend on the thickness of the prepreg and the composite material to be formed, but for example, the curing temperature can be selected in the range of 10 to 180°C and the curing time can be selected in the range of 5 minutes to 200 hours. From the viewpoint of productivity, the curing temperature is preferably 80 to 180°C and the curing time is preferably in the range of 10 minutes to 5 hours.

[0084] From the viewpoint of production using a tow- or tape-shaped prepreg, the composite material of the present invention is suitably used for moldings having a hollow shape such as pipes, shafts, cylinders, tanks, etc. The composite material is also suitable as a material for forming high-pressure gas containers.

[0085] [High-Pressure Gas Container] The high-pressure gas container of the present invention contains the fiber-reinforced composite material. It is sufficient that at least a portion of the high-pressure gas container of the present invention is made of the fiber-reinforced composite material. For example, in the case of a high-pressure gas container having a liner and an outer layer provided so as to cover the outer surface of the liner, at least one of the liner and the outer layer may be made of the fiber-reinforced composite material. Furthermore, in the case of a linerless high-pressure gas container, the entire container may be made of the fiber-reinforced composite material.

[0086] Specific embodiments of high-pressure gas containers containing a fiber-reinforced composite material include (1) a configuration having a metal liner and an outer layer made of the fiber-reinforced composite material of the present invention, (2) a configuration having a resin liner and an outer layer made of the fiber-reinforced composite material of the present invention, (3) a configuration having a liner made of the fiber-reinforced composite material of the present invention and an outer layer made of a material other than the fiber-reinforced composite material, and (4) a configuration consisting only of a container made of the fiber-reinforced composite material of the present invention (linerless).

[0087] Examples of the metal used for the "metallic liner" in (1) above include light alloys such as aluminum alloys and magnesium alloys.

[0088] The resin used for the "resin liner" in (2) above is not particularly limited as long as it has excellent gas barrier properties and pressure resistance, and examples thereof include thermoplastic resins, cured products of thermosetting resins, and cured products of photocurable resins. Among these, thermoplastic resins are preferred from the viewpoint of ease of molding the liner. Examples of such thermoplastic resins include polyamide resins, polyester resins, polyolefin resins, polyimide resins, polycarbonate resins, polyetherimide resins, polyamideimide resins, polyphenylene etherimide resins, polyphenylene sulfide resins, polysulfone resins, polyethersulfone resins, polyarylate resins, liquid crystal polymers, polyetheretherketone resins, polyetherketone resins, polyetherketoneketone resins, polyetheretherketoneketone resins, and polybenzimidazole resins. One or more of these resins may be used in combination. From the viewpoint of gas barrier properties and pressure resistance, the thermoplastic resin is preferably at least one resin selected from the group consisting of polyamide resins and polyolefin resins, and more preferably polyamide resins. In addition, from the viewpoint of improving impact resistance, the resin liner may contain the above-mentioned stress relaxation component.

[0089] The "outer layer made of a material other than the fiber-reinforced composite material" in (3) above is preferably an outer layer made of a fiber-reinforced composite material other than the fiber-reinforced composite material of the present invention, from the viewpoint of improving reinforcement.

[0090] In the above embodiments (1) to (3), the outer layer can be formed so as to cover the outer surface of the main body of the liner without any gaps. The outer layer may be provided directly on the outer surface of the liner. Alternatively, one or more other layers may be provided on the outer surface of the liner, and the outer layer may be provided on the surface of the other layers. For example, an adhesive layer may be provided between the liner and the outer layer to improve adhesion between the liner and the outer layer.

[0091] When the high-pressure gas container is of the above embodiment (1) or (2), the thickness of the outer layer made of the fiber-reinforced composite material of the present invention can be appropriately selected depending on the capacity, shape, etc. of the high-pressure gas container. From the viewpoint of imparting high gas barrier properties and impact resistance, the thickness is preferably 100 μm or more, more preferably 200 μm or more, and even more preferably 400 μm or more, and from the viewpoint of reducing the size and weight of the high-pressure gas container, the thickness is preferably 80 mm or less, more preferably 60 mm or less.

[0092] When the high-pressure gas container is of the above embodiment (3), the thickness of the liner made of the fiber-reinforced composite material of the present invention can be appropriately selected depending on the capacity, shape, etc. of the high-pressure gas container. From the viewpoints of gas barrier properties and pressure resistance, the thickness is preferably 100 μm or more, more preferably 200 μm or more, and even more preferably 400 μm or more, and from the viewpoints of miniaturization and weight reduction of the high-pressure gas container, the thickness is preferably 60 mm or less, more preferably 40 mm or less.

[0093] When the high-pressure gas container is of the above embodiment (4), the thickness of the container made of the fiber-reinforced composite material of the present invention can be appropriately selected depending on the capacity, shape, etc. of the high-pressure gas container. From the viewpoint of gas barrier properties and pressure resistance, the thickness is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 5 mm or more, and from the viewpoint of miniaturization and weight reduction of the high-pressure gas container, the thickness is preferably 80 mm or less, more preferably 60 mm or less.

[0094] The content of reinforcing fibers in a liner, outer layer, or high-pressure gas container made of the fiber-reinforced composite material of the present invention is preferably in a range such that the volume fraction of reinforcing fibers 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 obtaining high strength and high elastic modulus. Furthermore, from the viewpoint of gas barrier properties, impact resistance, and moldability, the volume fraction is preferably 0.85 or less, more preferably 0.80 or less, even more preferably 0.75 or less, and even more preferably 0.70 or less. The volume fraction of reinforcing fibers can be calculated in the same manner as above.

[0095] Among the above, from the viewpoint of light weight and the requirement for high gas barrier properties for the fiber reinforced composite material, the high-pressure gas container is preferably any one of the above-mentioned embodiments (2), (3) and (4), and embodiment (3) or (4) is more preferable.

[0096] The high-pressure gas container may further include components made of materials other than the fiber-reinforced composite material, such as a mouthpiece, a valve, etc. The surface of the high-pressure gas container may be formed with any layer, such as a protective layer, a paint layer, or a rust-preventing layer.

[0097] The gas to be stored in the high-pressure gas container may be any gas that is in a gaseous state at 25°C and 1 atm, and examples thereof include hydrogen, oxygen, carbon dioxide, nitrogen, argon, LPG, alternatives to chlorofluorocarbons, methane, etc. Among these, hydrogen is preferred from the viewpoint of the effectiveness of the present invention.

[0098] <Method for Manufacturing High-Pressure Gas Container> As a method for manufacturing a high-pressure gas container of the present invention, the manufacturing methods described above for manufacturing fiber-reinforced composite materials can be used as appropriate, depending on the form of the reinforcing fiber or prepreg used. When manufacturing a high-pressure gas container using a tow- or tape-shaped prepreg, the tow- or tape-shaped prepreg can be formed by a filament winding method, a tape winding method, a braiding method, a 3D printer method, or the like, to manufacture the high-pressure gas container. When the high-pressure gas container is in the form (1) or (2) above, the tow- or tape-shaped prepreg can be wound using a filament winding method or a tape winding method so as to cover the outer surface of a metal or resin liner, and then heat-cured to form an outer layer made of a fiber-reinforced composite material, thereby manufacturing the high-pressure gas container. When the high-pressure gas container is in the form (3) or (4) above, the high-pressure gas container can be manufactured by forming the tow- or tape-shaped prepreg into a container shape by a filament winding method, a tape winding method, a braiding method, a 3D printer method, or the like, and then heat-curing the prepreg.

[0099] 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.

[0100] <Glass transition temperature (Tg)> Using a differential scanning calorimeter "DSC25" (manufactured by TA Instruments), approximately 5 mg of the thermosetting resin composition of each example was heated to 30 to 250°C at a heating rate of 10°C / min to completely cure. This cured product was cooled to 30°C and then heated again to 30 to 225°C at a heating rate of 10°C / min, this operation being repeated twice, and the Tg of the cured product was determined from the measurement chart after the second heating.

[0101] <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) using a precision universal testing machine (Shimadzu Corporation's "Autograph AGX-plus"), and the 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: Elongation (%) = (length of test specimen at break - initial length of test specimen) / (initial length of test specimen) x 100 Grip distance: 115 mm Load cell (tensile force): 1 kN Tensile speed: 1 mm / min (tensile direction: longitudinal direction of the test specimen)

[0102] <Standard Deviation of Elongation> The elongation measurement was carried out three times using three test pieces, and the standard deviation was calculated and shown in Table 1. The smaller the value, the less variation there is in the physical properties of the cured product, and the better the results.

[0103] <Shore D Hardness> A cured product (test piece) of the thermosetting resin composition was prepared in the same manner as in the elongation measurement. The test piece was placed on a horizontal surface in an environment of 23°C, and the Shore D hardness was measured by pressing it against an Asker Rubber Hardness Tester Type D (manufactured by Kobunshi Keiki Co., Ltd.). The Shore D hardness was measured and shown in the table. A larger value indicates higher hardness.

[0104] <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 (weeks) until the viscosity of the thermosetting resin composition became at least twice the initial viscosity was measured and shown in the table. 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.).

[0105] Examples 1 to 15 and Comparative Examples 1 and 2 (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.

[0106]

[0107] The components listed in Table 1 are as follows: <Epoxy resin (A)> (A) jER807: bisphenol F diglycidyl ether (liquid epoxy resin), "jER807" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 168 g / equivalent (A) jER828: bisphenol A diglycidyl ether (liquid epoxy resin), "jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / equivalent (A) jER1004: bisphenol A (polymer type) diglycidyl ether (polymer type / solid epoxy resin), "jER1004" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 1026 g / equivalent

[0108] <(Meth)acrylate Compound (B)> (B1) Poly(butadiene-co-acrylonitrile) with acryloyloxy groups at both ends: "Hypro1300X33LC" manufactured by Chori GLEX (B2-1) Ethoxylated (2) Bisphenol A dimethacrylate, １ =R ２ =CH ３ , R ３ =R ４ =CH ３, m=n=1 (m+n=2) (B2-2) Urethane dimethacrylate: a compound in which, in the general formula (B2-2), R ５ is an alkylene group having 3 carbon atoms, X is a hexamethylene group, and Y is a divalent group represented by the general formula (Y1) (R ６ and R ７ is a methyl group). (B2-3) Urethane acrylate xylene resin: a urethane acrylate having a structure derived from xylene resin, "NIKANOL XUAT" manufactured by Fudow Co., Ltd. (B2-4): an ethoxylated (5) bisphenol A dimethacrylate, １ =R ２ =CH ３ , R ３ =R ４ =CH ３ , a compound in which m = n = 5 (m + n = 10), "SR-480" manufactured by Arkema

[0109] <Epoxy resin curing agent (C)> (C) DY-9577: boron trichloride amine complex (amine component: N,N-dimethyl-n-octylamine), manufactured by HUNTSMAN "Accelerator DY 9577"

[0110] <Thermal Radical Polymerization Initiator (D)> (D) PERHEXA 25B: 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, "PERHEXA 25B" manufactured by NOF Corporation

[0111] <Natural silica pulverized product (E)> (E-1) Natural silica pulverized product, D50: 1.13 μm, uniformity coefficient K: 3.38 (E-2) Natural silica pulverized product, D50: 4.00 μm, uniformity coefficient K: 3.99 (E-3) Natural silica pulverized product, D50: 5.67 μm, uniformity coefficient K: 5.83

[0112] Table 1 shows that the cured products of the thermosetting resin compositions of the present invention achieved a glass transition temperature of 80°C or higher and an elongation of 4% or higher. The thermosetting resin compositions also had a long pot life. Among these, the thermosetting resin compositions of Examples 1 to 7 and 10 to 15 showed little variance in the measured elongation values ​​and achieved a cured product Tg of 85°C or higher. In contrast, the thermosetting resin composition (epoxy resin composition) of Comparative Example 1, which did not contain component (B) or component (D), had a short pot life and the cured product elongation did not reach 4%. Furthermore, the thermosetting resin composition of Comparative Example 2, which did not contain component (B1), also did not achieve a cured product elongation of 4%.

[0113] According to the present invention, it is possible to provide a thermosetting resin composition which gives a cured product having a high glass transition temperature and elongation and which has a long pot life, a cured product thereof, a prepreg, a fiber-reinforced composite material, and a high-pressure gas container containing the fiber-reinforced composite material. The high-pressure gas container can be produced by filament winding molding using the prepreg of the present invention, and it is also possible to produce a high-pressure gas container with a plastic liner or a linerless high-pressure gas container.

Claims

1. Component (A): epoxy resin, Component (B): (meth)acrylate compound, Component (C): an epoxy resin curing agent, and Component (D): a thermal radical polymerization initiator, A thermosetting resin composition comprising: The component (B) contains poly(butadiene-co-acrylonitrile) (B1) having acryloyloxy groups at both ends, and a polyfunctional (meth)acrylate (B2) other than the component (B1), The thermosetting resin composition, wherein the component (C) comprises a boron amine complex.

2. The thermosetting resin composition according to claim 1 , wherein the component (B2) comprises a polyfunctional (meth)acrylate containing an aromatic ring.

3. The thermosetting resin composition according to claim 1, wherein the content of the component (B) in the thermosetting resin composition is 5 to 50 parts by mass based on 100 parts by mass of the component (A).

4. The thermosetting resin composition according to claim 1, wherein the content of the component (B1) in the component (B) is 1 to 70 mass%.

5. 2. The thermosetting resin composition of claim 1, wherein the boron amine complex is a boron trichloride amine complex.

6. 2. The thermosetting resin composition according to claim 1, wherein the amine component in the boron amine complex is a trialkylamine.

7. A cured product of the thermosetting resin composition according to any one of claims 1 to 6.

8. A prepreg comprising the thermosetting resin composition according to any one of claims 1 to 6 and reinforcing fibers.

9. The prepreg of claim 8 , wherein the prepreg is a tow prepreg.

10. A fiber-reinforced composite material obtained by curing the prepreg according to claim 8.

11. A high pressure gas bottle comprising the fiber reinforced composite material of claim 10.