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

Abstract

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, a cured product thereof, a prepreg, a fiber-reinforced composite material, and a high-pressure gas container comprising the fiber-reinforced composite material, the component (B) contains a poly (butadiene-CO-acrylonitrile) (B1) having acryloyloxy groups at both ends and a polyfunctional (meth) acrylate (B2) other than the component (B1), and the component (C) contains a boron-amine complex.

Description

Technical Field

[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 comprising the fiber-reinforced composite material. Background Art

[0002] In recent years, natural gas vehicles (CNG vehicles) and fuel cell vehicles (FCVs) have become popular in consideration of the environment. Fuel cell vehicles use fuel cells as their power source, and hydrogen refueling stations are indispensable for compressing hydrogen as their fuel into high pressure and filling the vehicle.

[0003] As a high-pressure gas storage tank used as a fuel cell vehicle hydrogen refueling station or a vehicle-mounted fuel tank for a CNG vehicle or a fuel cell vehicle, steel tanks have been used so far, but a lighter high-pressure gas storage tank using a resin material for the tank liner or the outer layer is being developed. By making the vehicle-mounted fuel tank lighter, there is an advantage of being able to improve the fuel efficiency of the vehicle on which it is mounted.

[0004] Pressure vessels such as high-pressure gas storage tanks generally have a metal lining and an outer layer provided to cover the outer surface of the lining. However, in recent years, in order to produce lighter pressure vessels, studies have been conducted on the production of plastic-lined pressure vessels and unlined pressure vessels.

[0005] As a method for producing a pressure vessel, there is known a method of producing a pressure vessel by filament winding molding using a tow prepreg (also called Towpreg) in which reinforcing fibers are pre-impregnated with an epoxy resin composition.

[0006] Prepregs and curable resin compositions suitable for prepregs have also been studied. For example, in Patent Document 1, as a prepreg useful for forming high-strength and high-toughness fiber-reinforced plastics, a prepreg comprising carbon fibers and a matrix resin is disclosed, wherein the matrix resin is a curable resin composition comprising a bisphenol-type epoxy resin, a (meth)acrylate compound having more than two functions, and a curing agent, wherein the curing agent comprises dicyandiamide and a free radical polymerization agent, and the cured product of the curable resin composition has a prescribed bending elastic modulus and elongation at break. In addition, a method for making a tubular body by winding the prepreg around a mandrel is also described.

[0007] Patent Document 2 discloses a curable resin composition for prepreg useful for molding high-strength and high-toughness fiber-reinforced plastics, comprising two epoxy resins satisfying prescribed requirements, bifunctional or higher-functional (meth)acrylate compounds, and a curing agent.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent No. 6993549

[0011] Patent Document 2: Japanese Patent Application Publication No. 2022-27815 Summary of the invention

[0012] Problem that the invention aims to solve

[0013] For the thermosetting resin composition used in the matrix resin of the prepreg, in order to ensure the long-term storage of the prepreg, a long pot life is required. In addition, in order to ensure heat resistance and high toughness in the fiber-reinforced composite material obtained by curing the prepreg, for the thermosetting resin composition used in the matrix resin of the prepreg, the glass transition temperature and elongation of the cured product are required to be high. However, in the disclosed technologies of Patent Documents 1 and 2, it is difficult to meet all these required properties.

[0014] The present invention aims to provide a thermosetting resin composition which can produce a cured product having a high glass transition temperature and elongation and a long pot life, a cured product thereof, a prepreg, a fiber-reinforced composite material, and a high-pressure gas container comprising the fiber-reinforced composite material.

[0015] Solutions for solving problems

[0016] The present inventors have found that the above-mentioned problems can be solved by using a predetermined (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.

[0017] That is, the present invention relates to the following contents.

[0018] [1] A thermosetting resin composition comprising: component (A): an epoxy resin, component (B): a (meth)acrylate compound, component (C): an epoxy resin curing agent, and component (D): a thermal free radical polymerization initiator, wherein the component (B) comprises poly(butadiene-co-acrylonitrile) (B1) having acryloyloxy groups at both ends and a multifunctional (meth)acrylate (B2) other than the component (B1), and the component (C) comprises a boron amine complex.

[0019] [2] The thermosetting resin composition according to [1] above, wherein the component (B2) comprises a polyfunctional (meth)acrylate containing an aromatic ring.

[0020] [3] The thermosetting resin composition according to [1] or [2], wherein the content of the component (B) is 5 to 50 parts by mass based on 100 parts by mass of the component (A) in the thermosetting resin composition.

[0021] [4] The thermosetting resin composition according to any one of [1] to [3] above, wherein the content of the component (B1) in the component (B) is 1 to 70% by mass.

[0022] [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.

[0023] [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.

[0024] [7] A cured product, which is a cured product of the thermosetting resin composition according to any one of [1] to [6] above.

[0025] [8] A prepreg comprising the thermosetting resin composition according to any one of [1] to [6] above and reinforcing fibers.

[0026] [9] The prepreg according to [8] above, wherein the prepreg is a tow prepreg.

[0027]

[10] A fiber-reinforced composite material obtained by curing the prepreg described in [8] or [9] above.

[0028]

[11] A high-pressure gas container comprising the fiber-reinforced composite material described in

[10] above.

[0029] Effects of the Invention

[0030] According to the present invention, a thermosetting resin composition having a high glass transition temperature and high elongation and a long pot life, a cured product thereof, a prepreg, a fiber-reinforced composite material, and a high-pressure gas container comprising the fiber-reinforced composite material can be provided. The high-pressure gas container can be manufactured by filament winding using the prepreg of the present invention, or can be made into a plastic-lined high-pressure gas container or an unlined high-pressure gas container. DETAILED DESCRIPTION

[0031] [definition]

[0032] In this specification, "(meth)acrylate" includes both acrylate and methacrylate.

[0033] In this specification, "normal temperature" means 25°C unless otherwise specified.

[0034] [Thermosetting resin composition]

[0035] The thermosetting resin composition of the present invention (hereinafter also referred to as "the composition of the present invention") contains:

[0036] Ingredient (A): Epoxy resin,

[0037] Component (B): (meth)acrylate compound,

[0038] Component (C): epoxy resin curing agent, and

[0039] Component (D): a thermal radical polymerization initiator, wherein the component (B) comprises poly(butadiene-co-acrylonitrile) (B1) having acryloyloxy groups at both ends and a polyfunctional (meth)acrylate (B2) other than the component (B1), and the component (C) comprises a boron amine complex.

[0040] The composition of the present invention has the above-mentioned structure, and can obtain a cured product having a high glass transition temperature (Tg) and elongation, and further has a long pot life.

[0041] The reason why the above-mentioned effects are obtained in the present invention is not yet clear, but is considered to be as follows.

[0042] 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) functions as a thermal radical polymerization initiator for curing the (meth)acrylate compound (B).

[0043] Thermosetting (epoxy) resin compositions containing epoxy resins and epoxy resin curing agents generally have excellent curability and heat resistance, but when used in high-pressure gas containers that require high toughness, the low elongation of the cured product becomes a problem. In addition, epoxy resin compositions generally cure quickly, so, in particular, for use in prepregs stored at room temperature, it is also necessary to improve the pot life.

[0044] By making the component (C) used in the thermosetting resin composition of the present invention contain a boron amine complex, the pot life is improved. In addition, it is believed that by making the composition of the present invention a mixture of the epoxy resin curing system of the component (A)-component (C) and the (meth)acrylate curing system of the component (B)-component (D), the probability of contact between the component (A) and the component (C) in the composition becomes low, and the pot life is further improved.

[0045] Furthermore, the component (B) used in the present invention comprises poly(butadiene-co-acrylonitrile) (B1) having acryloyloxy groups at both ends and a multifunctional (meth)acrylate (B2) other than the component (B1). It is believed that by making the component (B) contain the specific diacrylate having a rubber structure, namely the component (B1), the elongation of the cured product is improved, and by making the component (B) contain the component (B2), the excessive decrease in Tg of the cured product caused by the use of the component (B1) can be suppressed.

[0046] <Ingredient (A): Epoxy resin>

[0047] The epoxy resin (A) used in the present invention is not particularly limited as long as it is a multifunctional epoxy resin having two or more epoxy groups, but is preferably a multifunctional epoxy resin containing an aromatic ring or an alicyclic structure in the molecule from the viewpoint of increasing Tg of the cured product.

[0048] Specific examples of the epoxy resin (A) include at least one selected from the group consisting of epoxy resins having glycidylamino groups derived from m-phenylenediamine, epoxy resins having glycidylamino groups derived from p-phenylenediamine, epoxy resins having glycidylamino groups derived from 1,3-bis(aminomethyl)cyclohexane, epoxy resins having glycidylamino groups derived from 1,4-bis(aminomethyl)cyclohexane, epoxy resins having glycidylamino groups derived from diaminodiphenylmethane, epoxy resins having glycidylamino groups and / or glycidyloxy groups derived from p-aminophenol, epoxy resins having glycidyloxy groups derived from resorcinol, epoxy resins having glycidyloxy groups derived from bisphenol A, epoxy resins having glycidyloxy groups derived from bisphenol F, and epoxy resins having glycidyloxy groups derived from phenol novolac. One or more of the above epoxy resins may be used.

[0049] Among the above, from the viewpoint of increasing Tg of the cured product, the epoxy resin (A) preferably contains as a main component at least one selected from the group consisting of epoxy resins having a glycidyl amino group derived from m-phenylenediamine, epoxy resins having a glycidyl amino group derived from p-phenylenediamine, epoxy resins having a glycidyl ether group derived from bisphenol A, and epoxy resins having a glycidyl ether group derived from bisphenol F, and more preferably contains as a main component at least one selected from the group consisting of epoxy resins having a glycidyl ether group derived from bisphenol A and epoxy resins having a glycidyl ether group derived from bisphenol F.

[0050] It should be noted that the "main component" mentioned here means that other components may be contained within the scope not departing from the gist of the present invention, and preferably 50 to 100 mass %, more preferably 70 to 100 mass %, and even more preferably 90 to 100 mass % of the whole.

[0051] The epoxy resin (A) may be any of a solid epoxy resin and a liquid epoxy resin. From the viewpoint of easy impregnation into reinforcing fibers when applied to prepreg, the epoxy resin (A) preferably contains a liquid epoxy resin as a main component. "Solid epoxy resin" refers to an epoxy resin that has no fluidity at 25°C, and "liquid epoxy resin" refers to an epoxy resin that has fluidity at 25°C.

[0052] The epoxy equivalent (functional group equivalent) of the epoxy resin (A) is not particularly limited, but is preferably 1,500 g / equivalent or less, more preferably 1,200 g / equivalent or less, further preferably 1,000 g / equivalent or less, further preferably 800 g / equivalent or less, further preferably 500 g / equivalent or less, further preferably 300 g / equivalent or less, further preferably 250 g / equivalent or less, further preferably 220 g / equivalent or less, further preferably 200 g / equivalent or less, and is preferably 120 g / equivalent or more from the viewpoint of curability.

[0053] 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.

[0054] <Component (B): (meth)acrylate compound>

[0055] The (meth)acrylate compound (B) used in the present invention comprises poly(butadiene-co-acrylonitrile) (B1) having acryloyloxy groups at both ends and a polyfunctional (meth)acrylate (B2) other than the component (B1).

[0056] (Poly(butadiene-co-acrylonitrile) having acryloyloxy groups at both ends) (B1)

[0057] The component (B1) used in the present invention is a diacrylate having acryloyloxy groups at both ends of a main chain having a copolymer structure of butadiene and acrylonitrile.

[0058] From the viewpoint of increasing Tg and elongation of the cured product, the content of the structural unit derived from acrylonitrile in the 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.

[0059] 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. When Mw is 1,000 or more, it is easy to contribute to an improvement in the elongation of the cured product, while when it is 30,000 or less, it is easy to suppress a decrease in Tg of the cured product.

[0060] Examples of commercially available products of the component (B1) include "Hypro1300X33LC" manufactured by CHORI GLEX CO., LTD.

[0061] The content of component (B1) in component (B) is preferably 1 to 70% by mass, more preferably 5 to 60% by mass, further preferably 10 to 60% by mass, further preferably 15 to 60% by mass, further preferably 15 to 50% by mass. If the content of component (B1) in component (B) is 1% by mass or more, it is easy to contribute to the improvement of the elongation of the cured product, and if it is 70% by mass or less, it is possible to suppress the reduction of the Tg of the cured product and reduce the deviation of the physical properties of the cured product.

[0062] (Multifunctional (meth)acrylate (B2) other than component (B1))

[0063] The component (B2) used in the present invention may be any (meth)acrylate other than the component (B1) having two or more (meth)acryloyl groups. In addition, the component (B2) is preferably a (meth)acrylate having no glycidyl group.

[0064] 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 polyisocyanates and polyols, polyester (meth)acrylates having a main skeleton derived from polyols, etc. Among them, from the viewpoint of increasing Tg and elongation of the cured product, at least one selected from the group consisting of urethane (meth)acrylates and polyester (meth)acrylates is preferred.

[0065] The number of (meth)acrylic acid groups in component (B2) is preferably 2 to 6, more preferably 2 to 4, further preferably 2 to 3, and further preferably 2. If the number of (meth)acrylic acid groups in component (B2) is 2 or more, it is easy to contribute to the improvement of Tg of the cured product, while if it is 6 or less, the elongation of the cured product can be maintained.

[0066] From the viewpoint of increasing Tg of the cured product, the component (B2) preferably contains a polyfunctional (meth)acrylate containing an aromatic ring.

[0067] 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 selected from the group consisting of a benzene ring and a naphthalene ring is preferred, and a benzene ring is more preferred.

[0068] The number of aromatic rings possessed by the component (B2) may be 1 or more, and is preferably 2 or more from the viewpoint of increasing Tg of the cured product.

[0069] Specific examples of the polyfunctional (meth)acrylate containing an aromatic ring used as component (B2) include di(meth)acrylate having a structure derived from biphenol, di(meth)acrylate having a structure derived from bisphenol A, di(meth)acrylate having a structure derived from bisphenol F, di(meth)acrylate having a fluorene structure, di(meth)acrylate having a structure derived from an aromatic hydrocarbon formaldehyde resin, and the like, and one or more of these can be used. The above di(meth)acrylate may be any of epoxy di(meth)acrylate, urethane di(meth)acrylate, and polyester di(meth)acrylate.

[0070] The aromatic hydrocarbon formaldehyde resin is a resin obtained by reacting an aromatic hydrocarbon with formaldehyde. As the aromatic hydrocarbon, at least one selected from the group consisting of benzene, xylene, toluene, mesitylene, unimerized trimethylolbenzene, ethylbenzene, propylbenzene, decylbenzene, cyclohexylbenzene, biphenyl, methylbiphenyl, naphthalene, methylnaphthalene, dimethylnaphthalene, ethylnaphthalene, anthracene, methylanthracene, dimethylanthracene, ethylanthracene and binaphthyl can be cited, preferably at least one selected from the group consisting of xylene, toluene and mesitylene, more preferably xylene. It should be noted that xylene formaldehyde resin is also called "xylene resin", toluene formaldehyde resin is also called "toluene resin", and mesitylene formaldehyde resin is also called "mesitylene resin".

[0071] As the polyfunctional (meth)acrylate containing an aromatic ring used as component (B2), from the viewpoint of improving the Tg and elongation of the cured product, it is further preferred to be 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), and a di(meth)acrylate having a structure derived from an aromatic hydrocarbon formaldehyde resin.

[0072]

[0073] 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. m and n represent the number of repeating units and each independently represents a number of 0 to 20.

[0074]

[0075] In the formula, R 1 and R 2 Same as above, 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 greater than 1. r+1 Xs and r Ys may all be the same or different from each other.

[0076] In the above general formula (B2-1), R 1 and R 2 Preferably, methyl, R 3 and R 4 Preferred is methyl.

[0077] From the viewpoint of further improving the Tg and elongation of the cured product, in the general formula (B2-1), m and n are each independently preferably a number of 1 to 15, more preferably 1 to 10, and even more preferably a number of 2 to 6. In addition, m+n is a number of 0 to 40, and from the viewpoint of further improving the Tg and elongation of the cured product, it is preferably a number of 2 to 30, more preferably 2 to 20, and even more preferably a number of 4 to 12.

[0078] In the general formula (B2-2), R 1 and R 2 Preferably it is methyl. 5 R is an alkylene group having 2 to 6 carbon atoms, and the alkylene group may be a linear or branched chain. 5 It is preferably an alkylene group having 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

[0079] X in the general formula (B2-2) is a divalent group, which is a residue of a diisocyanate represented by OCN-X-NCO. Examples of the diisocyanate include chain aliphatic 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; and chain aliphatic diisocyanates such as 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, and 1,5-pentamethylene diisocyanate. Aliphatic diisocyanates containing alicyclic structures such as methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,2-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, and norbornane diisocyanate; diisocyanates containing aromatic rings such as m-phenylene diisocyanate, p-phenylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, naphthylene-1,4-diisocyanate, and naphthylene-1,5-diisocyanate. One or more of these diisocyanates can be used.

[0080] When Y in the general formula (B2-2) does not contain an aromatic ring, the diisocyanate is a diisocyanate containing an aromatic ring. When Y in the general formula (B2-2) contains an aromatic ring, from the viewpoint of improving the elongation of the cured product, the diisocyanate is preferably at least one selected from the group consisting of a linear aliphatic diisocyanate and an aliphatic diisocyanate containing an alicyclic structure, more preferably at least one selected from the group consisting of hexamethylene diisocyanate, 1,2-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane and isophorone diisocyanate, and further preferably hexamethylene diisocyanate.

[0081] Y in the general formula (B2-2) is a divalent group, which is a residue of a diol represented by HO-Y-OH. Examples of the diol include chain aliphatic diols such as ethylene glycol, propylene glycol, 1,3-propylene glycol, 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 alicyclic structures such as cyclohexanedimethanol and tricyclodecane dimethanol; diols containing aromatic rings such as biphenol, bisphenol A, bisphenol F, bisphenoxyfluorene ethanol, and diols obtained by adding ethylene oxide, propylene oxide, or caprolactone to these diols. One or more of these diols can be used.

[0082] From the viewpoint of improving Tg and elongation of the cured product, the diol is preferably at least one selected from the group consisting of linear aliphatic diols and diols containing an aromatic ring, more preferably a diol containing an aromatic ring, and still 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 thereto.

[0083] It is more preferable that Y in the above-mentioned general formula (B2-2) is a divalent group represented by the following general formula (Y1).

[0084]

[0085] 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, and each independently represents a number of 0 to 20. * represents a connecting bond.

[0086] 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.

[0087] Moreover, as a commercially available item of the di(meth)acrylate which has a structure derived from an aromatic hydrocarbon formaldehyde resin used as a component (B2), "NIKANOL XUAT" (urethane acrylate xylene resin) manufactured by Fudow Co., Ltd. etc. are mentioned.

[0088] From the viewpoint of increasing the Tg of the cured product, the content of the polyfunctional (meth)acrylate containing an aromatic ring in component (B2) is preferably 30% by mass or more, more preferably 50% by mass or more, further preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, and is 100% by mass or less.

[0089] As component (B2), polyfunctional (meth)acrylates not containing an aromatic ring, such as α,ω-alkanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate, can also be used.

[0090] The content of component (B2) in component (B) is preferably 30 to 99% by mass, more preferably 40 to 95% by mass, further preferably 40 to 90% by mass, further preferably 40 to 85% by mass, further preferably 50 to 85% by mass. If the content of component (B2) in component (B) is 30% by mass or more, it is easy to contribute to the improvement of Tg of the cured product, and if it is 99% by mass or less, the elongation of the cured product can be maintained and the deviation of the physical properties of the cured product can be reduced.

[0091] Component (B) may contain (meth)acrylates other than components (B1) and (B2) such as monofunctional (meth)acrylates in addition to components (B1) and (B2) for the purpose of reducing the viscosity of the composition.

[0092] Among them, from the viewpoint of increasing Tg of the cured product, the total content of component (B1) and component (B2) in component (B) is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and is 100% by mass or less.

[0093] The content of the component (B) in the thermosetting resin composition is preferably 5 to 50 parts by mass, more preferably 5 to 45 parts by mass, and further preferably 10 to 45 parts by mass relative to 100 parts by mass of the component (A). If the content of the component (B) in the thermosetting resin composition is 5 parts by mass or more relative to 100 parts by mass of the component (A), it is easy to achieve a long pot life, and if it is 50 parts by mass or less, it is easy to maintain the Tg of the cured product.

[0094] <Epoxy resin curing agent (C)>

[0095] From the viewpoint of achieving a long pot life, the epoxy resin curing agent (C) used in the present invention contains a boron amine complex.

[0096] 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, further preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, and is 100% by mass or less.

[0097] Examples of the boron amine complex include halogenated boron amine complexes, etc. Examples of the halogenated boron amine complex include boron trifluoride amine complexes and boron trichloride amine complexes, and boron trichloride amine complexes are preferred from the viewpoint of achieving a long pot life.

[0098] Examples of the amine component in the boron amine complex include alkylamines, alkanolamines, and cyclic aliphatic amines.

[0099] Examples of the alkylamine 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.

[0100] Examples of the alkanolamine include monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, N-methylethanolamine, N-methylisopropanolamine, N-butylethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, and N-methyldiisopropanolamine.

[0101] Examples of the cyclic aliphatic amine include piperidine and N,N-dicyclohexylmethylamine.

[0102] 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 further preferably N,N-dimethyloctylamine.

[0103] Examples of commercially available products of the boron amine complex used as the component (C) include "Accelerator DY9577" (boron trichloride amine complex, amine component: N,N-dimethyl-n-octylamine) manufactured by HUNTSMAN.

[0104] Component (C) may also contain epoxy resin curing agents other than boron amine complexes. Examples of epoxy resin curing agents other than boron amine complexes include amine curing agents, phenol curing agents, acid anhydride curing agents, hydrazide curing agents, and the like, and one or more of these can be used.

[0105] However, from the viewpoint of achieving a long pot life, the content of the epoxy resin curing agent other than the boron amine complex in component (C) is preferably 70% by mass or less, more preferably 50% by mass or less, further preferably 30% by mass or less, further preferably 20% by mass or less, further preferably 10% by mass or less, further preferably 5% by mass or less, and the lower limit is 0% by mass.

[0106] 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 further preferably 1 to 10 parts by mass relative to 100 parts by mass of component (A). If the content of component (C) in the thermosetting resin composition is 0.1 parts by mass or more relative to 100 parts by mass of component (A), it is easy to ensure curability, and if it is 40 parts by mass or less, it is easy to achieve a long pot life.

[0107] <Component (D): Thermal Radical Polymerization Initiator>

[0108] The component (D) used in the present invention may be any compound as long as it generates radicals by heating to cure the component (B), and examples thereof include azo compounds and organic peroxides.

[0109] Examples of the azo compound include azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (ABVN), 4,4'-azobis(4-cyanovaleric acid) (ABCVA), 2,2'-azobis(2-methylbutyronitrile) (AMBN), 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH), 2,2'-azobis(2-methylpropionic acid) dimethyl ester, and 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride. One or more of these may be used.

[0110] Examples of the organic peroxide 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 hydroperoxide, and tert-butyl cumyl peroxide. dialkyl peroxides such as diisobutyl peroxide, di(3,5,5-trimethylhexanol) peroxide, dilauroyl peroxide, disuccinic acid peroxide, benzoyl peroxide, etc.; diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, bis(4-tert-butylcyclohexyl) peroxydicarbonate, di(-2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, etc.; cumyl peroxyneodecanoate, 1,1,3,3-tetramethyl peroxyneodecanoate, etc. 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 peroxy-laurate, tert-Butyl peroxy-3,5,5-trimethylhexanoate, tert-Hexyl peroxyisopropyl monocarbonate, tert-Butyl peroxyisopropyl monocarbonate, tert-Butyl Peroxyesters such as tert-butyl peroxyacetate, tert-hexyl peroxybenzoate and tert-butyl peroxybenzoate; dialkyl peroxides such as diisopropyl peroxide, α,α'-di(tert-butyl peroxy)diisopropylbenzene, tert-butyl peroxyisopropylbenzene, 2,5-dimethyl-2,5-di(tert-butyl peroxy)hexane and 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexyne-3, and one or more thereof can be used.

[0111] Among the above, from the viewpoint of the curability of the component (B) and the viewpoint of achieving a long pot life when the composition is stored at room temperature, as the component (D), an organic peroxide is preferred, more preferably at least one selected from the group consisting of peroxyketal, hydroperoxide, diacyl peroxide, peroxydicarbonate, peroxyester and dialkyl peroxide, further preferably dialkyl peroxide, and further preferably 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0112] 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, further preferably 0.1 to 2 parts by mass, and further preferably 0.5 to 2 parts by mass relative to 100 parts by mass of component (B). If the content of component (D) in the thermosetting resin composition is 0.01 parts by mass or more relative to 100 parts by mass of component (B), it is easy to ensure curability, and if it is 5 parts by mass or less, it is easy to achieve a long pot life.

[0113] <Ingredient (E): Natural silica powder>

[0114] The thermosetting resin composition may further contain natural silica powder as a component (E). When the thermosetting resin composition contains the component (E), the hardness of the obtained cured product can be increased while suppressing a decrease in elongation.

[0115] Natural silica is a general term for natural siliceous rocks produced in Japan and around the world, and examples thereof include quartz sand containing SiO2 and further containing impurities such as Al and Fe. Natural silica pulverizer is obtained by finely pulverizing the above-mentioned natural silica.

[0116] From the viewpoint of improving the hardness of the obtained cured product, D50 of component (E) measured by laser scattering / diffraction method is preferably 0.5 to 10 μm, and the uniformity coefficient K represented by D60 / D10 is preferably 2 to 8.

[0117] When the thermosetting resin composition contains component (E), the content of component (E) in the thermosetting resin composition is preferably 0.01 to 10% by mass, more preferably 0.05 to 5.0% by mass, and further preferably 0.1 to 3.0% by mass. If the content of component (E) in the thermosetting resin composition is 0.01% by mass or more, it helps to improve the hardness of the obtained cured product, and if it is 10% by mass or less, it can improve the hardness while suppressing the decrease in the elongation of the cured product.

[0118] It should be noted that the content of the component (E) includes not only the natural silica powder intentionally blended in the thermosetting resin composition but also the natural silica powder mixed in the raw materials derived from the composition or in the production process of the composition.

[0119] <Other ingredients>

[0120] The thermosetting resin composition may contain other components such as fillers, modifying components such as plasticizers, flow regulating components such as thixotropic agents, reactive or non-reactive diluents, pigments, leveling agents, thickeners, and stress relaxation components, depending on the application.

[0121] Among the above, as stress relieving components, elastomer particles such as silicone elastomer particles, butyl acrylate elastomer particles, polyetheramine elastomer particles, and other rubber particles can be cited. In addition, liquid rubber components such as epoxidized polybutadiene can also be used. Commercially available products of stress relieving components include "KaneAce" B series, FM series, M series, MX series manufactured by Kaneka Co., Ltd., and liquid epoxidized polybutadiene, i.e., "EPOLEA DPB3600" and "EPOLEAD PB4700" manufactured by Daicel Co., Ltd.

[0122] When the thermosetting resin composition contains a stress relaxing component, the content of the stress relaxing component is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass in the solid content of the thermosetting resin composition. It should be noted that the "solid content of the thermosetting resin composition" refers to the amount after removing water and organic solvent from the total amount of the thermosetting resin composition.

[0123] <Solvent>

[0124] From the viewpoint of improving the impregnation property into the reinforcing fibers, the thermosetting resin composition of the present invention may further contain a solvent.

[0125] Examples of the solvent include alcohol 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 solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ether solvents such as diethyl ether and diisopropyl ether; hydrocarbon solvents such as toluene, and one or more of them can be used.

[0126] From the viewpoint of solubility of the blended components and the viewpoint of ease of removal of the solvent, the solvent is preferably at least one selected from the group consisting of alcohol solvents, ester solvents, ketone solvents and hydrocarbon 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.

[0127] From the viewpoint of effectively exhibiting the effects of the present invention, the total content of components (A) to (D) in the thermosetting resin composition is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and even more preferably 95% by mass or more, and is 100% by mass or less in the solid content of the thermosetting resin composition.

[0128] When the thermosetting resin composition contains a solvent, the content thereof is not particularly limited, but from the viewpoint of improving the impregnation property into the reinforcing fibers, it is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more in the thermosetting resin composition, and from the viewpoint of easy removal of the solvent, it is preferably 80% by mass or less, and more preferably 70% by mass or less.

[0129] The thermosetting resin composition may be a solvent-free composition that does not substantially contain a solvent. A solvent-free thermosetting resin composition means that the content of the solvent in the thermosetting resin composition is preferably less than 5% by mass, more preferably 2% by mass or less, further preferably 1% by mass or less, further preferably 0.5% by mass or less, further preferably 0% by mass or less.

[0130] There is no particular limitation on the method for preparing the thermosetting resin composition, and the composition can be prepared by mixing components (A) to (D) and other components used as needed using a known method and apparatus. There is no particular limitation on the order in which the components contained in the thermosetting resin composition are mixed. When components (A) and (B) are high in viscosity, it is preferred to heat and mix components (A) and (B) at 80°C to 120°C in advance, cool to below 80°C, and then mix components (C) and (D). This is to avoid thermal polymerization of component (C) during the preparation of the thermosetting resin composition.

[0131] [cured material]

[0132] The cured product of the thermosetting resin composition of the present invention (hereinafter, also referred to as "cured product of the present invention") is obtained by thermally curing the thermosetting resin composition of the present invention described above by a known method. The curing conditions of the thermosetting resin composition can be appropriately selected according to the application and form, and the curing temperature is preferably 90°C to 160°C, and more preferably 100°C to 150°C.

[0133] The form of the cured product of the present invention is not particularly limited and can be selected according to the application. For example, when the application of the thermosetting resin composition is a coating, the cured product of the composition is usually in the form of a film. It should be noted that from the viewpoint of effectively exerting the effect of the present invention, the cured product of the present invention is preferably a matrix resin of a fiber-reinforced composite material described later.

[0134] From the viewpoint of the matrix resin used for the fiber-reinforced composite material described later and the high-pressure gas container, etc., 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, further preferably 87° C. or higher, further preferably 90° C. or higher, and usually 200° C. or lower. The Tg of the cured product can be specifically measured by the method described in the Examples.

[0135] [Prepreg]

[0136] The prepreg of the present invention comprises the aforementioned thermosetting resin composition and reinforcing fibers.

[0137] The reinforcing fibers used in the prepreg may be short fibers, long fibers, or continuous fibers. Among these, from the viewpoint of using the obtained prepreg as a material for constituting a high-pressure gas container described later, long fibers or continuous fibers are preferred, and continuous fibers are more preferred.

[0138] It should be noted that 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. In addition, continuous fibers refer to fiber bundles having a fiber length exceeding 100 mm.

[0139] Examples of the shape of the continuous fibers include tows, sheets, and tapes, and examples of the continuous fibers constituting the sheets or tapes include unidirectional (UD) materials, woven fabrics, and nonwoven fabrics.

[0140] From the viewpoint of manufacturing a high-pressure gas container using a prepreg by a filament winding method or a tape winding method, the shape of the continuous fiber is preferably a tow or a tape, and more preferably a tow. From the viewpoint of easily obtaining high strength and high elastic modulus, the number of continuous fiber bundles (number of fibers) constituting the tow is preferably 3K to 50K, and more preferably 6K to 40K.

[0141] In the continuous fibers, the average fiber length of the continuous fiber bundle is not particularly limited, but is preferably 1 to 10,000 m, more preferably 100 to 10,000 m, from the viewpoint of molding processability.

[0142] From the viewpoint of molding processability and the viewpoint of easily obtaining high strength and high elastic modulus, the average fineness of the continuous fiber bundle is preferably 50 to 2000 tex (g / 1000 m), more preferably 200 to 1500 tex, and further preferably 500 to 1500 tex.

[0143] Furthermore, the average tensile elastic modulus of the continuous fiber bundle is preferably 50 to 1000 GPa.

[0144] As the material of the reinforcing fiber, for example, inorganic fibers such as carbon fiber, glass fiber, basalt fiber, metal fiber, boron fiber, ceramic fiber, and organic fibers such as aramid fiber, polyoxymethylene fiber, aromatic polyamide fiber, poly(p-phenylene benzobisoxazole) fiber, and ultra-high molecular weight polyethylene fiber can be listed. Among them, from the viewpoint of obtaining high strength, inorganic fibers are preferred, from the viewpoint of light weight, high strength, and high elastic modulus, at least one selected from the group consisting of carbon fiber, glass fiber, and basalt fiber is preferred, and from the viewpoint of strength and lightness, carbon fiber is more preferred.

[0145] Examples of the carbon fiber include polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, etc. In addition, carbon fibers made from plant-derived raw materials such as lignin and cellulose may also be used.

[0146] The reinforcing fibers may be treated with a treatment agent. Examples of the treatment agent include a surface treatment agent and a sizing agent.

[0147] As the surface treatment agent, a silane coupling agent is preferred, and examples thereof 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)acryloyl group, and a silane coupling agent having a mercapto group.

[0148] Examples of the sizing agent include urethane sizing agents, epoxy sizing agents, acrylic sizing agents, polyester sizing agents, vinyl ester sizing agents, polyolefin sizing agents, polyether sizing agents, and carboxylic acid sizing agents, and one or more of these sizing agents may be used. Examples of sizing agents in combination of two or more of these sizing agents include urethane / epoxy sizing agents, urethane / acrylic sizing agents, and urethane / carboxylic acid sizing agents.

[0149] 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, 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 based on the reinforcing fiber.

[0150] As reinforcing fibers, commercial products may also be used. Commercial products of continuous carbon fibers (tows) include, for example, TORAYCAYARN "T300", "T300B", "T400HB", "T700SC", "T800SC", "T800HB", "T830HB", "T1000GB", "T100GC", "M35JB", "M40JB", "M46JB", "M50JB", "M55J", "M55JB", "M60JB", "M30SC", "Z600" series manufactured by Toray Industries, Ltd.; Tenax "HTA40" series and "HTS40" series manufactured by Teijin Limited. , "HTS45" series, "HTS45P12" 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, "HTS40MC" series, etc.; PYROFIL "HT", "IM", "HM" series, GRAFIL "HT" series, "DIALEAD" series carbon fiber tows manufactured by Mitsubishi Chemical Corporation, etc.

[0151] In addition, as commercially available products of continuous carbon fibers other than tows, TORAY CACLOTH "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 manufactured by Toray Industries, Ltd. " Series, "M40JB" series, "M46JB" series, "M50JB" series, "M55J" series, "M55JB" series, "M60JB" series, "M30SC" series, "Z600GT" series; PYROFIL "TR3110M", "TR3523M", "TR3524M", "TR6110HM", "TR6120HM", "TRK101M", "TRK510M", "TR3160TMS", "TRK979PQRW", "TRK976PQRW", "TR6185HM", "TRK180M" and other carbon fiber fabrics manufactured by Mitsubishi Chemical Corporation.

[0152] Regarding the content of reinforcing fibers in the prepreg, from the viewpoint of obtaining high strength and high elastic modulus, the volume fraction of reinforcing fibers in the prepreg is preferably in the range of 0.10 or more, more preferably 0.20 or more, further preferably 0.30 or more, and further preferably 0.40 or more. In addition, from the viewpoint of gas barrier properties, impact resistance, and formability, it is preferably in the range of 0.85 or less, more preferably 0.80 or less, and further preferably 0.70 or less.

[0153] The volume fraction Vf1 of the reinforcing fibers in the prepreg can be calculated by the following formula.

[0154] Vf1 = {mass of reinforcing fiber (g) / specific gravity of reinforcing fiber}÷[{mass of reinforcing fiber (g) / specific gravity of reinforcing fiber}+{mass of solid content of impregnated thermosetting resin composition (g) / specific gravity of solid content of thermosetting resin composition}]

[0155] In addition, from the viewpoint of obtaining the effects of the present invention, the total content of the solid content and reinforcing fibers constituting the thermosetting resin composition of the prepreg is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and the upper limit is 100% by mass.

[0156] <Shape and Manufacturing Method of Prepreg>

[0157] The shape of the prepreg varies depending on the form of the reinforcing fibers used, but a tow prepreg is preferred from the viewpoint of producing a high-pressure gas container by a filament winding method.

[0158] In addition, when using continuous fibers in the form of unidirectional (UD) materials, fabrics, nonwoven fabrics, etc., tape-shaped or sheet-shaped prepregs can also be made. Among them, from the viewpoint of manufacturing a high-pressure gas container by a tape winding method, a tape-shaped prepreg is preferred, and a UD tape is more preferred.

[0159] The method for producing the prepreg is not particularly limited, and the prepreg can be produced according to a conventional method. For example, after the reinforcing fibers are impregnated with the thermosetting resin composition, the prepreg is subjected to a drying step to remove the solvent as required, thereby obtaining the prepreg.

[0160] The method for impregnating the reinforcing fiber with the thermosetting resin composition is not particularly limited, and a known method can be appropriately used according to the form of the reinforcing fiber. For example, in the case of manufacturing a tow prepreg, the following method can be cited: the continuous fiber bundle unwound from the reel is immersed in a resin bath filled with the above-mentioned thermosetting resin composition, and the composition is impregnated and then pulled out from the resin bath. Then, a step of removing the excess thermosetting resin composition using a squeeze roller or the like can be performed.

[0161] The impregnation with the thermosetting resin composition may be performed under pressurized conditions or reduced pressure conditions as required.

[0162] Next, as needed, 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 can remove the solvent and do not excessively cure the thermosetting resin composition. From this viewpoint, for example, the drying temperature can be selected within the range of 30° C. to 120° C., and the drying time can be selected within the range of 10 seconds to 5 minutes.

[0163] The prepreg obtained through the drying step may be temporarily wound up to form a prepreg product, or may be continuously used for the production of a fiber-reinforced composite material after the drying step without being wound up.

[0164] [Fiber-reinforced composite materials]

[0165] The fiber-reinforced composite material of the present invention (hereinafter also referred to as "composite material") is obtained by curing the above-mentioned prepreg, and comprises a cured product of the above-mentioned thermosetting resin composition and reinforcing fibers. The fiber-reinforced composite material of the present invention has high heat resistance and impact resistance due to the presence of the cured product of the above-mentioned thermosetting resin composition.

[0166] The prepreg, thermosetting resin composition, reinforcing fiber, and preferred embodiments thereof used in the production of the composite material are the same as those described above.

[0167] <Content>

[0168] Regarding the content of reinforcing fibers in the fiber-reinforced composite material, from the viewpoint of obtaining high strength and high elastic modulus, the volume fraction of reinforcing fibers in the fiber-reinforced composite material is preferably in the range of 0.10 or more, more preferably 0.20 or more, further preferably 0.30 or more, and further preferably 0.40 or more. In addition, from the viewpoint of gas barrier properties, impact resistance, and formability, it is preferably in the range of 0.85 or less, more preferably 0.80 or less, and further preferably 0.70 or less.

[0169] The volume fraction Vf of the reinforcing fibers in the fiber-reinforced composite material can be calculated by the following formula.

[0170] Vf = {mass of reinforcing fiber (g) / specific gravity of reinforcing fiber} ÷ [{mass of reinforcing fiber (g) / specific gravity of reinforcing fiber} + {mass of cured product of thermosetting resin composition (g) / specific gravity of cured product of thermosetting resin composition}]

[0171] <Method for producing fiber-reinforced composite material>

[0172] The composite material can be manufactured by preforming the prepreg into a desired shape using the above-mentioned prepreg, and then curing the prepreg. For example, when the composite material of the present invention is applied to a hollow shaped body such as a pipe, a shaft, a gas cylinder, or a tank, a prepreg in a tow or tape shape can be used to form the composite material by a filament winding method, a tape winding method, a braiding method, a 3D printer, or the like.

[0173] In the filament winding method or the tape winding method, specifically, a composite material of a desired shape can be produced by winding a prepreg in the shape of a filament bundle or a tape around the outer surface of a balloon, a mandrel or a liner and then heating and curing it.

[0174] In the weaving method, for example, the following steps are performed: using a balloon or a mandrel, a prepreg in the shape of a tow or a tape is weaved in a unidirectional manner or in a braided structure by a braiding machine to form the prepreg, and then the prepreg is heated and cured. It should be noted that in the weaving method, the prepreg in the shape of a tow or a tape can also be formed into a tape without using a balloon or a mandrel.

[0175] When using a sheet-shaped prepreg using unidirectional (UD) materials, fabrics, non-woven fabrics, etc. as continuous fibers, one sheet or multiple sheets of prepreg can be placed in a mold and heated and cured under vacuum or pressure conditions to produce a composite material.

[0176] The curing method of the prepreg in the manufacture of the composite material is also not particularly limited, and is carried out by a known method at a temperature and time sufficient to cure the thermosetting resin composition contained in the prepreg. The curing conditions of the prepreg also depend on the thickness of the prepreg and the composite material formed, for example, the curing temperature can be selected in the range of 10°C 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 in the range of 80°C to 180°C and the curing time is preferably in the range of 10 minutes to 5 hours.

[0177] From the viewpoint of manufacturing using a prepreg in the form of a tow or a tape, the composite material of the present invention is suitable for use in hollow shaped bodies such as pipes, shafts, gas cylinders, tanks, etc. The composite material is suitable as a material for forming a high-pressure gas container.

[0178] [High-pressure gas container]

[0179] The high-pressure gas container of the present invention comprises the aforementioned fiber-reinforced composite material. The high-pressure gas container of the present invention only needs to be at least partially composed of the aforementioned fiber-reinforced composite material. For example, if it is a high-pressure gas container having a liner and an outer layer provided in a manner covering the outer surface of the liner, then at least one of the liner and the outer layer can be cited as being composed of the aforementioned fiber-reinforced composite material. In addition, if it is an unlined high-pressure gas container, then the container can be cited as a container in which the entire container is composed of the aforementioned fiber-reinforced composite material.

[0180] Specific embodiments of high-pressure gas containers containing fiber-reinforced composite materials include (1) a structure having a metal lining and an outer layer formed by the fiber-reinforced composite material of the present invention, (2) a structure having a resin lining and an outer layer formed by the fiber-reinforced composite material of the present invention, (3) a structure having a lining formed by the fiber-reinforced composite material of the present invention and an outer layer formed by a material other than the fiber-reinforced composite material, and (4) a structure including only a container (without lining) formed by the fiber-reinforced composite material of the present invention.

[0181] Examples of the metal used for the "metal lining" in (1) above include light alloys such as aluminum alloys and magnesium alloys.

[0182] The resin used in the "resin lining" of (2) above is not particularly limited as long as it is a resin having excellent gas barrier properties and pressure resistance, and examples thereof include thermoplastic resins, cured products of thermosetting resins, cured products of photocurable resins, etc. Among them, thermoplastic resins are preferred from the viewpoint of being able to easily form the lining.

[0183] Examples of the thermoplastic resin 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, polyetherketoneketone resins, polyetheretherketoneketone resins, polybenzimidazole resins, and the like. One of these resins or a combination of two or more thereof may be used.

[0184] From the viewpoint of gas barrier properties and pressure resistance, the thermoplastic resin is preferably at least one selected from the group consisting of polyamide resins and polyolefin resins, and more preferably a polyamide resin.

[0185] Furthermore, from the viewpoint of improving impact resistance, the resin lining may contain the above-mentioned stress relaxing component.

[0186] From the viewpoint of improving reinforcement, the "outer layer formed of a material other than the fiber-reinforced composite material" in (3) above is preferably an outer layer formed of a fiber-reinforced composite material other than the fiber-reinforced composite material of the present invention.

[0187] In the above-mentioned aspects (1) to (3), the outer layer may be formed so as to cover the outer surface of the main body portion of the liner without a gap.

[0188] The outer layer may also be directly disposed on the outer surface of the lining. Alternatively, one or more other layers may be disposed on the outer surface of the lining and disposed on the surface of the other layers. For example, in order to improve the closeness between the lining and the outer layer, an adhesive layer may be disposed between the lining and the outer layer.

[0189] In the case where the high-pressure gas container is of the above-mentioned form (1) or (2), the thickness of the outer layer formed by the fiber-reinforced composite material of the present invention can be appropriately selected according to the capacity, shape, etc. of the high-pressure gas container. From the viewpoint of imparting high gas barrier properties and impact resistance, it is preferably 100 μm or more, more preferably 200 μm or more, and further preferably 400 μm or more. From the viewpoint of miniaturization and lightweight of the high-pressure gas container, it is preferably 80 mm or less, and more preferably 60 mm or less.

[0190] In the case where the high-pressure gas container is of the aforementioned embodiment (3), the thickness of the lining formed by the fiber-reinforced composite material of the present invention can be appropriately selected according to the capacity, shape, etc. of the high-pressure gas container. From the viewpoint of gas barrier properties and pressure resistance, it is preferably 100 μm or more, more preferably 200 μm or more, and further preferably 400 μm or more. From the viewpoint of miniaturization and lightweight of the high-pressure gas container, it is preferably 60 mm or less, and more preferably 40 mm or less.

[0191] In the case where the high-pressure gas container is of the aforementioned embodiment (4), the thickness of the container formed by the fiber-reinforced composite material of the present invention can be appropriately selected according to 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 further preferably 5 mm or more. From the viewpoint of miniaturization and lightweight of the high-pressure gas container, the thickness is preferably 80 mm or less, and more preferably 60 mm or less.

[0192] Regarding the content of reinforcing fibers in the liner, outer layer or high-pressure gas container formed of the fiber-reinforced composite material of the present invention, from the viewpoint of obtaining high strength and high elastic modulus, the volume fraction of the reinforcing fibers is preferably in the range of 0.10 or more, more preferably 0.20 or more, further preferably 0.30 or more, and further preferably 0.40 or more. In addition, from the viewpoint of gas barrier properties, impact resistance and formability, it is preferably in the range of 0.85 or less, more preferably 0.80 or less, further preferably 0.75 or less, and further preferably 0.70 or less.

[0193] The volume fraction of the reinforcing fibers can be calculated by the same method as described above.

[0194] Among the above, from the viewpoint of lightness and the high gas barrier properties required of fiber-reinforced composite materials, the high-pressure gas container is preferably any one of the above (2), (3) or (4), and more preferably (3) or (4).

[0195] It should be noted that the high-pressure gas container may also have parts made of materials other than the fiber-reinforced composite material such as joints and valves. In addition, any layers such as a protective layer, a coating layer, and a rust-inhibiting agent layer may also be formed on the surface of the high-pressure gas container.

[0196] The gas to be stored in the high-pressure gas container may be any gas at 25°C and 1 atm, and may include, in addition to hydrogen, oxygen, carbon dioxide, nitrogen, argon, LPG, freon substitutes, methane, etc. Among them, hydrogen is preferred from the viewpoint of effectiveness of the present invention.

[0197] <Method for manufacturing high-pressure gas container>

[0198] As a method for manufacturing a high-pressure gas container of the present invention, the manufacturing method described in the manufacturing method of the above-mentioned fiber-reinforced composite material can be appropriately used according to the form of the reinforcing fiber or prepreg used. In the case of using a prepreg in the shape of a tow or a tape to manufacture a high-pressure gas container, the prepreg in the shape of a tow or a tape can be formed by a fiber winding method, a tape winding method, a braiding method, a 3D printer method, etc. to manufacture a high-pressure gas container.

[0199] In the case where the high-pressure gas container is of the above-mentioned method (1) or (2), a fiber winding method or a tape winding method can be used to wind a filament bundle or a tape-shaped prepreg in a manner that covers the outer surface of a metal or resin liner, and then heat and cure it to form an outer layer composed of a fiber-reinforced composite material to manufacture a high-pressure gas container.

[0200] In the case where the high-pressure gas container is of the aforementioned method (3) or (4), the high-pressure gas container can be manufactured by forming a filament or tape-shaped prepreg into a container shape by a fiber winding method, a tape winding method, a weaving method, a 3D printer method, etc., and then heating and curing it.

[0201] Example

[0202] The present invention will be described in detail below by way of examples and comparative examples, but the present invention is not limited to the following examples. It should be noted that the measurements and evaluations in the present examples were performed by the following methods.

[0203] <Glass transition temperature (Tg)>

[0204] Using a differential scanning calorimeter "DSC25" (manufactured by TA Instruments), about 5 mg of the thermosetting resin composition of each example was heated to 30°C to 250°C at a heating rate of 10°C / min to completely cure. The cured product was cooled to 30°C and then heated again to 30°C to 225°C at a heating rate of 10°C / min twice, and the Tg of the cured product was determined from the measurement chart during the second heating.

[0205] <Elongation>

[0206] The thermosetting resin composition prepared in each example was formed into a flat plate of 200 mm × 200 mm × 2 mm thick, and heat cured in a hot air oven at 130°C for 180 minutes to produce a cured product. A strip piece of 180 mm × 15 mm × 2 mm thick was cut from the cured product to prepare a tensile test piece.

[0207] The test piece was subjected to a tensile test (N=3) using a precision universal testing machine (Autograph AGX-plus, Shimadzu Corporation) under the following conditions, and the elongation was calculated by the following formula: The length of the test piece at break was calculated from the displacement of the load cell at break.

[0208] Elongation (%) = (length of the test piece at break - initial length of the test piece) / (initial length of the test piece) × 100

[0209] Distance between fixtures: 115mm

[0210] Force sensor (tensile force): 1kN

[0211] Tensile speed: 1 mm / min (tensile direction: length direction of the test piece)

[0212] <Standard deviation of elongation>

[0213] The standard deviation of the elongation measurement performed three times using three test pieces was calculated and shown in the table. The smaller the value, the less variation in the physical properties of the cured product, which means that the cured product is better.

[0214] <Shore D Hardness>

[0215] The cured product (test piece) of the thermosetting resin composition was prepared by the same method as the elongation measurement described above. The test piece was placed in a horizontal place under a 23°C environment, and an ASKER rubber hardness meter type D (manufactured by Gaozheng Keiki Co., Ltd.) was pressed to measure the Shore D hardness, which is shown in the table. The larger the value, the higher the hardness.

[0216] <Applicable period>

[0217] After measuring the initial viscosity of the thermosetting resin composition prepared in each example at 23° C., 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 reached more than twice the initial viscosity was measured and shown in the table.

[0218] The viscosity of the thermosetting resin composition was measured using an E-type viscometer "TVE-22H Viscometer Cone-Plate Type" (manufactured by Toki Sangyo Co., Ltd.).

[0219] Examples 1 to 15, Comparative Examples 1 to 2 (Preparation and Evaluation of Thermosetting Resin Compositions)

[0220] The components shown in Table 1 were blended and mixed in the parts by mass shown in Table 1 to obtain a thermosetting resin composition.

[0221] The obtained thermosetting resin composition was evaluated by the above-mentioned method. The results are shown in Table 1.

[0222] In addition, the compounding amounts (parts by mass) in Table 1 are all amounts of effective ingredients.

[0223] [Table 1]

[0224]

[0225] The components described in Table 1 are as follows.

[0226] <Epoxy resin (A)>

[0227] (A) jER807: bisphenol F diglycidyl ether (liquid epoxy resin), "jER807" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 168 g / equivalent

[0228] (A) jER828: bisphenol A diglycidyl ether (liquid epoxy resin), "jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / equivalent

[0229] (A) jER1004: bisphenol A (polymer type) diglycidyl ether (polymer type / solid epoxy resin), "jER1004" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 1026 g / equivalent

[0230] <(Meth)acrylate compound (B)>

[0231] (B1) Poly(butadiene-co-acrylonitrile) having acryloyloxy groups at both ends: "Hypro1300X33LC" manufactured by Chori Glex Co., Ltd.

[0232] (B2-1) ethoxylated (2) bisphenol A dimethacrylate, wherein R1 =R 2 =CH3, R 3 =R 4 =CH3, m=n=1(m+n=2)

[0233] (B2-2) Urethane dimethacrylate: In the above 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 (R 6 and R 7 (methyl) urethane dimethacrylate

[0234] (B2-3) Urethane acrylate xylene resin: Urethane acrylate having a structure derived from a xylene resin, "NIKANOL XUAT" manufactured by Fudow Co., Ltd.

[0235] (B2-4): ethoxylated (5) bisphenol A dimethacrylate, R 1 =R 2 =CH3, R 3 =R 4 =CH3, m=n=5 (m+n=10), "SR-480" manufactured by Arkema

[0236] <Epoxy resin curing agent (C)>

[0237] (C) DY-9577: Boron trichloride amine complex (amine component: N,N-dimethyloctylamine), "Accelerator DY 9577" manufactured by HUNTSMAN

[0238] <Thermal Radical Polymerization Initiator (D)>

[0239] (D) PERHEXA25B: 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, "PERHEXA25B" manufactured by NOF Corporation

[0240] <Natural silica powder (E)>

[0241] (E-1) Natural silica powder, D50: 1.13 μm, uniformity coefficient K: 3.38

[0242] (E-2) Natural silica powder, D50: 4.00 μm, uniformity coefficient K: 3.99

[0243] (E-3) Natural silica powder, D50: 5.67 μm, uniformity coefficient K: 5.83

[0244] As can be seen from Table 1, the cured product of the thermosetting resin composition of the present invention can achieve a glass transition temperature of 80° C. or higher and an elongation of 4% or higher. In addition, the thermosetting resin composition has a long pot life.

[0245] Among them, the thermosetting resin compositions of Examples 1 to 7 and 10 to 15 had less variation in the measured values ​​of elongation, and furthermore, the cured products could achieve Tg of 85° C. or higher.

[0246] In contrast, the thermosetting resin composition (epoxy resin composition) of Comparative Example 1, which does not contain component (B) and component (D), has a short pot life and the elongation of the cured product does not reach 4%. In addition, the elongation of the cured product of the thermosetting resin composition of Comparative Example 2, which does not contain component (B1), does not reach 4%.

[0247] Industrial Applicability

[0248] According to the present invention, a thermosetting resin composition having a high glass transition temperature and high elongation and a long pot life, a cured product thereof, a prepreg, a fiber-reinforced composite material, and a high-pressure gas container comprising the fiber-reinforced composite material can be provided. The high-pressure gas container can be manufactured by filament winding using the prepreg of the present invention, or can be made into a plastic-lined high-pressure gas container or an unlined high-pressure gas container.

Claims

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

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

3. The thermosetting resin composition according to claim 1 or 2, wherein The content of the component (B) is 5 to 50 parts by mass based on 100 parts by mass of the component (A) in the thermosetting resin composition.

4. The thermosetting resin composition according to any one of claims 1 to 3, wherein The content of the component (B1) in the component (B) is 1 to 70% by mass.

5. The thermosetting resin composition according to any one of claims 1 to 4, wherein The boron amine complex is a boron trichloride amine complex.

6. The thermosetting resin composition according to any one of claims 1 to 5, wherein The amine component in the boron amine complex is a trialkylamine. 7 . A cured product, which is a cured product of the thermosetting resin composition according to claim 1 . 8 . A prepreg comprising the thermosetting resin composition according to claim 1 and reinforcing fibers.

9. The prepreg according to claim 8, wherein The prepreg is a tow prepreg. 10 . A fiber-reinforced composite material obtained by curing the prepreg according to claim 8 or 9.

11. A high-pressure gas container comprising the fiber-reinforced composite material according to claim 10.

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