High-pressure gas storage tank

Abstract

A liner for a pressure vessel made from a fiber-reinforced composite material including a cured product of a thermosetting resin or a thermosetting resin composition and continuous reinforcing fibers, and a high-pressure gas storage tank equipped with said liner.

Description

Technical Field

[0001] The present invention relates to a liner for a pressure vessel and a high-pressure gas storage tank provided with the liner.

Background Art

[0002] In recent years, the spread of natural gas vehicles (CNG vehicles) and fuel cell vehicles (FCVs) that consider the environment has been progressing. A fuel cell vehicle uses a fuel cell as a power source, and it is essential to develop hydrogen stations that compress hydrogen, which is the fuel, to high pressure and fill it into the vehicle. As a high-pressure gas storage tank used for a hydrogen station for fuel cell vehicles or an in-vehicle fuel tank for CNG vehicles, fuel cell vehicles, etc., steel tanks have been used so far, but the development of a lighter high-pressure gas storage tank using a resin material for the liner or its outer layer of the tank has been underway. By reducing the weight of the in-vehicle fuel tank, there are advantages such as improving the fuel efficiency of the vehicle equipped with it.

[0003] As a resin material constituting a high-pressure gas storage tank, it is known to use a resin having gas barrier properties and a fiber-reinforced composite material (FRP) in which the resin is impregnated with reinforcing fibers. For example, Patent Document 1 discloses a resin liner having a resin such as nylon as a main material having gas barrier properties and an elastomer containing an additive having hydrogen adsorption performance, and a high-pressure hydrogen tank in which an FRP layer is laminated on the outer peripheral surface thereof. Patent Document 2 discloses a pressure vessel having a liner and an outer layer of the liner, the outer layer being composed of a composite material containing continuous fibers and a predetermined gas barrier polyamide resin impregnated with the continuous fibers, and a liner composed of the composite material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] For a liner for a high-pressure gas storage tank, barrier properties, strength of the gas to be stored, and heat resistance at a level that can withstand the temperature rise during tank use are also required. In the resin liner disclosed in Patent Document 1 and the liner for a pressure vessel disclosed in Patent Document 2, thermoplastic resins are both used. However, in the liner using a thermoplastic resin, there is a limitation that it is difficult to impart heat resistance exceeding the melting point or glass transition temperature of the resin used. In addition, a liner using a thermoplastic resin is usually thermoformed using a mold, but since it is necessary to go through a series of molding cycles of heating and melting the resin, filling it into the mold, and cooling, it is desired to further improve productivity. A thermoplastic resin with a lower melting point or glass transition temperature can perform heating and melting and filling into the mold in a shorter time, but the heat resistance of the resulting liner becomes lower.

[0006] An object of the present invention is to provide a liner for a pressure vessel having light weight, gas barrier properties, heat resistance, and high strength, and excellent in productivity, and a high-pressure gas storage tank equipped with the liner.

Means for Solving the Problems

[0007] The present inventors have found that a liner for a pressure vessel composed of a fiber-reinforced composite material containing a cured product of a thermosetting resin or a thermosetting resin composition and continuous reinforcing fibers can solve the above problems. That is, the present invention relates to the following [1] to [3]. [1] A liner for a pressure vessel composed of a fiber-reinforced composite material containing a cured product of a thermosetting resin or a thermosetting resin composition and continuous reinforcing fibers. [2] A process of forming a tow prepreg composed of the thermosetting resin or thermosetting resin composition and a continuous reinforcing fiber bundle by using a braiding method or a winding method, the manufacturing method of the liner for a pressure vessel described in [1] above. [3] A high-pressure gas storage tank equipped with the liner for a pressure vessel described in [1] above. [Advantages of the Invention]

[0008] According to the present invention, it is possible to provide a liner for a pressure vessel that has lightweight, gas barrier properties such as hydrogen gas, heat resistance, and high strength, and is also excellent in productivity. Since the liner for a pressure vessel of the present invention has high gas barrier properties, heat resistance, and strength, it can be used as it is as a pressure vessel such as a high-pressure gas storage tank without providing an outer layer. The high-pressure gas storage tank equipped with the liner for a pressure vessel is suitable as a high-pressure gas storage tank for vehicle-mounted use, and since it is lightweight, it is possible to improve the fuel consumption of the vehicle on which it is mounted. [Brief Description of the Drawings]

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0010] [Liner for Pressure Vessel] The liner for a pressure vessel of the present invention (hereinafter, also simply referred to as "the liner of the present invention") is composed of a fiber-reinforced composite material containing a cured product of a thermosetting resin or a thermosetting resin composition and continuous reinforcing fibers. In this specification, the "liner for a pressure vessel" means a member that constitutes the inner surface of a pressure vessel, that is, a member that directly contacts the contents of the pressure vessel. Therefore, a pressure vessel composed only of the liner for a pressure vessel of the present invention is also included in the "liner" defined in the present invention.

[0011] Since the liner of the present invention is composed of a fiber-reinforced composite material containing a cured product of a thermosetting resin or a thermosetting resin composition and continuous reinforcing fibers, it has light weight, gas barrier properties such as hydrogen gas, heat resistance, and high strength, and is also excellent in productivity. The reason is as follows. A conventionally known liner for a pressure vessel containing a thermoplastic resin as a matrix resin and continuous reinforcing fibers has limitations in imparting heat resistance because the thermoplastic resin inevitably has a melting point or a glass transition temperature (Tg). On the other hand, the liner of the present invention containing a cured product of a thermosetting resin or a thermosetting resin composition as a matrix resin can achieve higher heat resistance because the cured product either does not have a Tg or has a higher Tg than the thermoplastic resin if it has a Tg. Furthermore, in the molding of a liner containing a thermoplastic resin and continuous reinforcing fibers, a cycle of heating the material to a temperature exceeding the melting point or Tg of the thermoplastic resin, then molding, and then cooling is required, so the molding time tends to be long. Also, a mandrel, a mold, etc. for molding into a desired liner shape are essential. In contrast, for the liner of the present invention using a thermosetting resin or a thermosetting resin composition and continuous reinforcing fibers, if a braiding method or the like described later is used, a method of continuously molding can be adopted without using a mandrel, a mold, etc. after impregnating the continuous reinforcing fibers with the thermosetting resin or the thermosetting resin composition. Therefore, the liner of the present invention is also excellent in productivity.

[0012] The liner of the present invention only needs to have a space filled with gas inside, and is usually hollow. The shape of the liner of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an embodiment of the liner for a pressure vessel of the present invention, and FIG. 2 is a perspective view thereof. In FIGS. 1 and 2, the liner 100 has a cylindrical portion 1 and two dome portions 21 and 22 that seal both ends (1a and 1b) of the cylindrical portion 1. Both of the dome portions 21 and 22 are hollow, and it is preferable that at least one of the dome portions (the dome portion 21 in FIG. 1) is provided with an opening 3 at the top of the dome portion for joining a valve or the like for the pressure vessel. In addition, when it is a liner used for a pressure vessel provided with other members such as an outer layer, a detachable portion or the like (not shown) for detaching and attaching to other members can also be provided on the liner 100.

[0013] The liner 100 of the present invention is composed of a fiber-reinforced composite material 10 containing a cured product of a thermosetting resin or a thermosetting resin composition and continuous reinforcing fibers. From the viewpoints of gas barrier properties, strength, impact resistance, and productivity, the fiber-reinforced composite material 10 constituting the liner 100 is preferably formed using a tow pre-preg composed of a thermosetting resin or a thermosetting resin composition and a continuous reinforcing fiber bundle. By molding using the tow pre-preg by a braiding method, a winding method, or the like, a liner 100 composed of a fiber-reinforced composite material 10 having a helical structure, a braided structure, a spiral structure, or the like can be obtained.

[0014] From the viewpoints of improving gas barrier properties, strength, impact resistance, etc., the fiber-reinforced composite material 10 constituting the liner 100 preferably has a braided structure (FIG. 3) or a spiral structure (FIG. 4). FIG. 3 and FIG. 4 are schematic plan views (partial enlarged views) showing an embodiment of the fiber-reinforced composite material 10 constituting the liner 100, and are obtained by cutting out the region A on the side surface of the liner 100 shown in FIG. 2. As shown in FIGS. 3 and 4, the braided structure and the spiral structure are structures in which the cured product 11 of the tow pre-preg composed of a thermosetting resin or a thermosetting resin composition and a continuous reinforcing fiber bundle is arranged in a braided shape or a spiral shape without gaps, thereby forming a hollow structure of the liner 100.

[0015] From the viewpoints of gas barrier properties, strength, impact resistance, and productivity, it is preferable that at least the cylindrical portion 1 constituting the liner 100 has a braided structure or a spiral structure. The dome portions 21 and 22 constituting the liner 100 may also be composed of the fiber-reinforced composite material 10 having a braided structure or a spiral structure, but are not particularly limited.

[0016] For example, if a tow pre-preg composed of a thermosetting resin or a thermosetting resin composition and a continuous reinforcing fiber bundle is used and formed by a braiding method, a liner having a braided structure can be manufactured. Further, if the tow pre-preg is used for one-way braiding or formed by a winding method, a liner having a spiral structure can be manufactured. A liner having a braided structure or a spiral structure is excellent in gas barrier properties, strength, and impact resistance, and is also advantageous in terms of productivity.

[0017] The liner 100 in FIGS. 1 and 2 may be formed by separately manufacturing and joining the cylindrical portion and the dome portion, or may be integrally formed with the cylindrical portion and the dome portion. From the viewpoint of the productivity of the liner, it is preferable that the cylindrical portion 1 and at least one dome portion are integrally formed. By using the braiding method or the winding method, the cylindrical portion and the dome portion of the liner can be easily integrally formed using the tow pre-preg. When separately manufacturing the dome portion of the liner, the manufacturing method is not particularly limited. For example, it can be manufactured by thermally pressing and molding a prepreg in which reinforcing fibers are impregnated in advance with a thermosetting resin or a thermosetting resin composition using a mold. When the thermosetting resin and the thermosetting resin composition to be used are solvent-free types, they can also be manufactured by known molding methods such as the Va-RTM (Vacuum assisted resin transfer molding) method, the RTM (Resin transfer molding) method, and the HP-RTM (High pressure resin transfer molding) method. At this time, examples of the thermosetting resin or the thermosetting resin composition constituting the dome portion and the reinforcing fibers include the same materials as those constituting the liner cylindrical portion. Alternatively, when separately manufacturing the dome portion of the liner, the dome portion can also be manufactured using a thermoplastic resin or a thermoplastic resin composition. The dome portion may be manufactured using a prepreg in which reinforcing fibers are impregnated or laminated with a thermoplastic resin or a thermoplastic resin composition. Examples of the thermoplastic resin include polyamide resin, polyester resin, polyolefin resin, polyimide resin, polycarbonate resin, polyetherimide resin, polyamideimide resin, polyphenylene etherimide resin, polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyarylate resin, liquid crystal polymer, polyetheretherketone resin, polyetherketone resin, polyetherketoneketone resin, polyetheretherketoneketone resin, polybenzimidazole resin, etc. One or more of these can be used in combination.

[0018] The thickness of the liner 100 (t in FIG. 1) can be appropriately selected according to the capacity and shape of the pressure vessel, the thickness of the continuous reinforcing fibers used, the outer diameter of the fiber bundle, etc. From the viewpoint of ensuring sufficient gas barrier properties and pressure resistance for gases such as hydrogen gas when used in a pressure vessel, the thickness of the liner is preferably 100 μm or more, more preferably 200 μm or more, still more preferably 400 μm or more. From the viewpoint of miniaturization and weight reduction of the liner and the pressure vessel, it is preferably 60 mm or less, more preferably 40 mm or less.

[0019] <Thermosetting resin, thermosetting resin composition> The thermosetting resin used for the liner of the present invention is not particularly limited as long as it is a resin that can be cured by heating. Further, the thermosetting resin composition used in the present invention is a composition containing the thermosetting resin. Examples of the thermosetting resin include at least one selected from the group consisting of epoxy resins, phenol resins, urea resins, melamine resins, unsaturated polyimide resins, silicone resins, urethane resins, casein resins, furan resins, alkyd resins, and xylene resins. Among these, an epoxy resin is preferable from the viewpoints of ease of impregnation into continuous reinforcing fibers and the heat resistance, strength, and gas barrier properties of the resulting cured product against gases such as hydrogen gas.

[0020] Examples of the epoxy resin composition containing an epoxy resin as the thermosetting resin include a two-component curing type epoxy resin composition containing an epoxy resin (epoxy group-containing compound) as the main agent and an epoxy resin curing agent. From the viewpoint of obtaining higher gas barrier properties and impact resistance, the thermosetting resin composition is preferably an epoxy resin composition, and the epoxy resin composition preferably contains an epoxy resin (A) and an epoxy resin curing agent (B) containing a reaction product (X) of the following component (x1) and component (x2). (x1) At least one selected from the group consisting of metaxylylenediamine and p-xylylenediamine (x2) At least one selected from the group consisting of unsaturated carboxylic acids represented by the following general formula (1) and derivatives thereof [Chem.] (In formula (1), R 1 , R 2 each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms.) From the viewpoint of enhancing the impregnation property into continuous reinforcing fibers, it is preferable that the epoxy resin composition further contains a solvent. Hereinafter, the above epoxy resin composition, which is a preferred embodiment of the thermosetting resin composition used in the present invention, will be described in detail.

[0021] (Epoxy resin (A)) The epoxy resin (A) (hereinafter, also simply referred to as "component (A)") is not particularly limited as long as it is a polyfunctional epoxy resin having two or more epoxy groups. However, in consideration of the expression of high gas barrier properties, a polyfunctional epoxy resin containing an aromatic ring or an alicyclic structure in the molecule is preferable. Specific examples of the polyfunctional epoxy resin include an epoxy resin having a glycidylamino group derived from metaxylylenediamine, an epoxy resin having a glycidylamino group derived from paraxylylenediamine, an epoxy resin having a glycidylamino group derived from 1,3-bis(aminomethyl)cyclohexane, an epoxy resin having a glycidylamino group derived from 1,4-bis(aminomethyl)cyclohexane, an epoxy resin having a glycidylamino group derived from diaminodiphenylmethane, an epoxy resin having a glycidylamino group and / or a glycidyloxy group derived from para-aminophenol, an epoxy resin having a glycidyloxy group derived from bisphenol A, an epoxy resin having a glycidyloxy group derived from bisphenol F, an epoxy resin having a glycidyloxy group derived from phenol novolak, and an epoxy resin having a glycidyloxy group derived from resorcinol. At least one resin selected from these can be mentioned. In order to improve various properties such as flexibility, impact resistance, and heat and moisture resistance, the above epoxy resins can also be used by mixing two or more of them in an appropriate ratio. Among these, from the viewpoint of gas barrier properties, as the epoxy resin (A), those mainly composed of at least one selected from the group consisting of an epoxy resin having a glycidylamino group derived from metaxylylenediamine, an epoxy resin having a glycidylamino group derived from paraxylylenediamine, and an epoxy resin having a glycidyloxy group derived from bisphenol F are preferable, and those mainly composed of an epoxy resin having a glycidylamino group derived from metaxylylenediamine are more preferable. Here, the "main component" means that other components may be included without departing from the gist of the present invention, preferably 50 to 100% by mass of the whole, more preferably 70 to 100% by mass, and still more preferably 90 to 100% by mass.

[0022] (Epoxy resin curing agent (B)) The epoxy resin curing agent (B) (hereinafter, also simply referred to as "component (B)") contains an epoxy resin curing agent (B) containing a reaction product (X) of the following component (x1) and component (x2) from the viewpoint of exhibiting high gas barrier properties and impact resistance. (x1) At least one selected from the group consisting of metaxylylenediamine and paraxylylenediamine (x2) At least one selected from the group consisting of unsaturated carboxylic acids represented by the following general formula (1) and derivatives thereof

Chemical formula

[0023] 〔Reaction product (X)〕 The reaction product (X) is a reaction product of the component (x1) and the component (x2). Component (x1) is used from the viewpoint of gas barrier properties, and metaxylylenediamine is preferable from the viewpoint of gas barrier properties. Component (x1) may be used alone or in combination of two.

[0024] Component (x2) is at least one selected from the group consisting of unsaturated carboxylic acids represented by the general formula (1) and derivatives thereof. From the viewpoint of exhibiting high gas barrier properties and impact resistance, R 1 in the general formula (1) is preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, still more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom. Also, from the viewpoint of exhibiting high gas barrier properties and impact resistance, R 2is preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, still more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom.

[0025] Examples of the derivative of the unsaturated carboxylic acid represented by the general formula (1) include esters, amides, acid anhydrides, and acid chlorides of the unsaturated carboxylic acid. As the ester of the unsaturated carboxylic acid, an alkyl ester is preferable, and from the viewpoint of obtaining good reactivity, the number of carbon atoms of the alkyl is preferably 1 to 6, more preferably 1 to 3, and still more preferably 1 to 2.

[0026] Examples of the unsaturated carboxylic acid and its derivative represented by the general formula (1) include acrylic acid, methacrylic acid, α-ethylacrylic acid, α-propylacrylic acid, α-isopropylacrylic acid, α-n-butylacrylic acid, α-t-butylacrylic acid, α-pentylacrylic acid, α-phenylacrylic acid, α-benzylacrylic acid, crotonic acid, 2-pentenoic acid, 2-hexenoic acid, 4-methyl-2-pentenoic acid, 2-heptenoic acid, 4-methyl-2-hexenoic acid, 5-methyl-2-hexenoic acid, 4,4-dimethyl-2-pentenoic acid, 4-phenyl-2-butenoic acid, cinnamic acid, o-methylcinnamic acid, m-methylcinnamic acid, p-methylcinnamic acid, 2-octenoic acid and other unsaturated carboxylic acids, and esters, amides, acid anhydrides, acid chlorides, etc. thereof. Among the above, from the viewpoint of exhibiting high gas barrier properties and impact resistance, component (x2) is preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid and their derivatives, more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid and their alkyl esters, still more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid and their alkyl esters, even more preferably an alkyl ester of acrylic acid, and even more preferably methyl acrylate. Component (x2) may be used alone or in combination of two or more.

[0027] When using unsaturated carboxylic acids, esters, or amides as component (x2), the reaction between component (x1) and component (x2) is carried out by mixing component (x1) and component (x2) under the conditions of 0 to 100 °C, more preferably 0 to 70 °C, and then performing a Michael addition reaction and an amide group formation reaction by dehydration, dealcoholization, or deamination under the conditions of 100 to 300 °C, preferably 130 to 250 °C. In this case, during the amide group formation reaction, in order to complete the reaction, the inside of the reaction apparatus can be depressurized at the final stage of the reaction as necessary. Also, it can be diluted using a non-reactive solvent as necessary. Furthermore, a catalyst such as phosphites can be added as a dehydrating agent or a dealcoholizing agent.

[0028] On the other hand, when using acid anhydrides or acid chlorides of unsaturated carboxylic acids as component (x2), it is carried out by performing a Michael addition reaction and an amide group formation reaction after mixing under the conditions of 0 to 150 °C, preferably 0 to 100 °C. In this case, during the amide group formation reaction, in order to complete the reaction, the inside of the reaction apparatus can be depressurized at the final stage of the reaction as necessary. Also, it can be diluted using a non-reactive solvent as necessary. Furthermore, a tertiary amine such as pyridine, picoline, lutidine, or trialkylamine can be added.

[0029] Since the amide group site formed by the reaction between component (x1) and component (x2) has a high cohesive force, the cured product of the epoxy resin composition using the epoxy resin curing agent (B) containing the reaction product (X) of component (x1) and component (x2) has high gas barrier properties and good adhesiveness to reinforcing fibers.

[0030] In the reaction product (X), the reaction molar ratio of component (x2) to component (x1) [(x2) / (x1)] is preferably in the range of 0.3 to 1.0, more preferably in the range of 0.6 to 1.0. If the above reaction molar ratio is 0.3 or more, a sufficient amount of amide groups is generated in the epoxy resin curing agent, and high-level gas barrier properties and adhesiveness to reinforcing fibers are exhibited. On the other hand, if the above reaction molar ratio is in the range of 1.0 or less, the amount of amino groups required for the reaction with epoxy groups in the epoxy resin (A) is sufficient, and it is also excellent in heat resistance and solubility in organic solvents.

[0031] The reaction product (X) may be a reaction product of the component (x1) and component (x2) with at least one compound selected from the group consisting of the following component (x3), component (x4) and component (x5). (x3)R 3 At least one selected from the group consisting of monocarboxylic acids represented by -COOH and their derivatives (R 3 represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms which may have a hydroxyl group, or an aryl group having 6 to 12 carbon atoms.) (x4) Cyclic carbonate (x5) Monoepoxy compound having 2 to 20 carbon atoms

[0032] Component (x3), R 3 The monocarboxylic acid represented by -COOH and its derivatives are used from the viewpoint of reducing the reactivity between the epoxy resin curing agent (B) containing the reaction product (X) and the epoxy resin (A) as necessary, and improving workability, pot life, etc. R 3 represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms which may have a hydroxyl group, or an aryl group having 6 to 12 carbon atoms, and R 3 is preferably an alkyl group having 1 to 3 carbon atoms or a phenyl group. Also R 3Examples of the derivative of the monovalent carboxylic acid represented by -COOH include esters, amides, acid anhydrides, and acid chlorides of the carboxylic acid. As the ester of the carboxylic acid, an alkyl ester is preferred, and the number of carbon atoms of the alkyl is preferably 1 to 6, more preferably 1 to 3, and even more preferably 1 to 2. Examples of the component (x3) include monovalent carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, lactic acid, glycolic acid, benzoic acid, and derivatives thereof. The component (x3) may be used alone or in combination of two or more.

[0033] The cyclic carbonate as the component (x4) is used as necessary from the viewpoint of reducing the reactivity between the epoxy resin curing agent (B) containing the reaction product (X) and the epoxy resin (A) and improving workability, pot life, etc. From the viewpoint of reactivity with the component (x1), the component (x4) is preferably a cyclic carbonate having a six-membered ring or less. For example, ethylene carbonate, propylene carbonate, glycerin carbonate, 1,2-butylene carbonate, vinylene carbonate, 4-vinyl-1,3-dioxolan-2-one, 4-methoxymethyl-1,3-dioxolan-2-one, 1,3-dioxan-2-one, etc. may be mentioned. Among these, from the viewpoint of gas barrier properties, at least one selected from the group consisting of ethylene carbonate, propylene carbonate, and glycerin carbonate is preferred. The component (x4) may be used alone or in combination of two or more.

[0034] The monoepoxy compound as the component (x5) is a monoepoxy compound having 2 to 20 carbon atoms and is used as necessary from the viewpoint of reducing the reactivity between the epoxy resin curing agent (B) containing the reaction product (X) and the epoxy resin (A) and improving workability, pot life, etc. From the viewpoint of gas barrier properties, the component (x5) is preferably a monoepoxy compound having 2 to 10 carbon atoms, and more preferably a compound represented by the following formula (2).

[0035] [Chemical formula] (In formula (2), R 4 represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group, a chloromethyl group, or R 5 -O-CH2-, and R 5 represents a phenyl group or a benzyl group.) Examples of the monoepoxy compound represented by the formula (2) include ethylene oxide, propylene oxide, 1,2-butylene oxide, styrene oxide, epichlorohydrin, phenyl glycidyl ether, and benzyl glycidyl ether. Component (x5) may be used alone or in combination of two or more.

[0036] When component (x3), component (x4), or component (x5) is used in the reaction product (X), any one compound selected from the group consisting of component (x3), component (x4), and component (x5) may be used alone or in combination of two or more.

[0037] Note that the reaction product (X) may be a reaction product obtained by further reacting with other components within a range not impairing the effects of the present invention, in addition to the above components (x1) to (x5). Examples of the other components herein include aromatic dicarboxylic acids or their derivatives. However, the usage amount of the "other components" is preferably 30% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less of the total amount of the reaction components constituting the reaction product (X).

[0038] The reaction product of component (x1) and component (x2) with at least one compound selected from the group consisting of component (x3), component (x4), and component (x5) is obtained by reacting at least one compound selected from the group consisting of component (x3), component (x4), and component (x5) with polyamine compound component (x1) in combination with component (x2). The reaction may be carried out by adding components (x2) to (x5) in any order and reacting with component (x1), or by mixing components (x2) to (x5) and reacting with component (x1).

[0039] The reaction between component (x1) and component (x3) can be carried out under the same conditions as the reaction between component (x1) and component (x2). When using component (x3), components (x2) and (x3) may be mixed and reacted with component (x1), or component (x1) and component (x2) may be reacted first and then component (x3) may be reacted. On the other hand, when using component (x4) and / or component (x5), it is preferable to first react component (x1) and component (x2), and then react with component (x4) and / or component (x5). The reaction between component (x1) and component (x4) and / or component (x5) is carried out by mixing component (x1) and component (x4) and / or component (x5) under the conditions of 25 to 200 °C, and performing an addition reaction under the conditions of 30 to 180 °C, preferably 40 to 170 °C. Also, a catalyst such as sodium methoxide, sodium ethoxide, potassium t-butoxide, etc. can be used as necessary. During the above reaction, in order to accelerate the reaction, component (x4) and / or component (x5) can be melted as necessary, or diluted with a non-reactive solvent and used.

[0040] Even when the reaction product (X) is a reaction product of the component (x1) and the component (x2) with at least one compound selected from the group consisting of the component (x3), the component (x4), and the component (x5), the reaction molar ratio [(x2) / (x1)] of the component (x2) to the component (x1) is preferably in the range of 0.3 to 1.0, more preferably in the range of 0.6 to 1.0, for the same reasons as described above. On the other hand, the reaction molar ratio [{(x3)+(x4)+(x5)} / (x1)] of the component (x3), the component (x4), and the component (x5) to the component (x1) is preferably in the range of 0.05 to 3.1, more preferably in the range of 0.07 to 2.5, and even more preferably in the range of 0.1 to 2.0. However, from the viewpoints of gas barrier properties, workability, pot life, etc., the reaction molar ratio [{(x2)+(x3)+(x4)+(x5)} / (x1)] of the components (x2) to (x5) to the component (x1) is preferably in the range of 0.35 to 2.5, more preferably in the range of 0.35 to 2.0.

[0041] The epoxy resin curing agent (B) may contain a curing agent component other than the reaction product (X). The "curing agent component other than the reaction product (X)" is a component other than the reaction product (X) having two or more functional groups capable of reacting with the epoxy groups in the epoxy resin (A). From the viewpoints of reactivity with the epoxy resin (A) and gas barrier properties, polyamine compounds having two or more amino groups in the molecule other than the component (x1), and modified products of polyamine compounds are preferably mentioned as components. However, from the viewpoint of exhibiting high gas barrier properties and impact resistance, the epoxy resin curing agent (B) preferably has a high content of the reaction product (X). From the above viewpoints, the content of the reaction product (X) in the epoxy resin curing agent (B) is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and still more preferably 90% by mass or more. The upper limit is 100% by mass.

[0042] Regarding the mixing ratio of the epoxy resin (A) and the epoxy resin curing agent (B) in the epoxy resin composition, it may generally be within the standard mixing range when producing a cured product by reacting the epoxy resin and the epoxy resin curing agent. Specifically, the ratio of the number of active amine hydrogens in the epoxy resin curing agent (B) to the number of epoxy groups in the epoxy resin (A) (number of active amine hydrogens in the epoxy resin curing agent (B) / number of epoxy groups in the epoxy resin (A)) is preferably in the range of 0.2 to 12.0. From the viewpoint of exhibiting high gas barrier properties and impact resistance, (number of active amine hydrogens in the epoxy resin curing agent (B) / number of epoxy groups in the epoxy resin (A)) is more preferably 0.4 to 10.0, still more preferably 0.6 to 8.0, even more preferably 0.9 to 6.0, and even more preferably in the range of more than 1.0 and 5.0 or less. From the viewpoint of further improving the impact resistance, (number of active amine hydrogens in the epoxy resin curing agent (B) / number of epoxy groups in the epoxy resin (A)) is even more preferably 1.1 or more, even more preferably 1.4 or more, and even more preferably 2.0 or more. From the viewpoint of further improving the barrier property of hydrogen gas, it is more preferably 4.0 or less, and even more preferably 3.2 or less.

[0043] (Solvent) The epoxy resin composition preferably further contains a solvent from the viewpoint of reducing the viscosity of the composition and enhancing the impregnation property into continuous reinforcing fibers. As the solvent, a non-reactive solvent is preferred. Specific examples thereof 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, 1-propoxy-2-propanol; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone and methyl isobutyl ketone; ether solvents such as diethyl ether and diisopropyl ether; hydrocarbon solvents such as toluene, etc. One or more of these can be used. From the viewpoints of the solubility of the epoxy resin (A) and the epoxy resin curing agent (B) and the ease of removing the solvent, at least one selected from the group consisting of alcohol solvents, ester solvents, and hydrocarbon solvents having 8 or less carbon atoms is preferable as the solvent, and at least one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, ethyl acetate, and toluene is more preferable, and at least one selected from the group consisting of methanol and ethyl acetate is even more preferable.

[0044] When the epoxy resin composition contains a solvent, its content is not particularly limited, but from the viewpoint of enhancing the impregnation property of the epoxy resin composition into the continuous reinforcing fiber, it is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably 30% by mass or more, and even more preferably 40% by mass or more. From the viewpoint of the ease of removing the solvent, it is preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0045] In the epoxy resin composition, within a range not impairing the effects of the present invention, if necessary, a thermosetting resin other than the epoxy resin (A), a coupling agent, a reactive diluent, a non-reactive diluent other than the solvent, a curing accelerator, a wetting agent, a tackifier, an antifoaming agent, a rust inhibitor, a lubricant, a pigment, an oxygen scavenger, an ultraviolet absorber, an antioxidant, and other additives may be further blended. When the epoxy resin composition contains the above additives, the total content of the above additives in the composition is preferably 20.0 parts by mass or less, more preferably 0.001 to 15.0 parts by mass, based on 100 parts by mass of the total amount of the epoxy resin (A) and the epoxy resin curing agent (B).

[0046] However, from the viewpoint of obtaining the effects of the present invention, the total content of the epoxy resin (A) and the epoxy resin curing agent (B) in the solid content of the epoxy resin composition is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and even more preferably 85% by mass or more, and the upper limit is 100% by mass. The "solid content of the epoxy resin composition" means the components excluding water and solvents in the epoxy resin composition.

[0047] The epoxy resin composition can be prepared by, for example, blending predetermined amounts of an epoxy resin (A), an epoxy resin curing agent (B), a solvent, and additives used as necessary, and then stirring and mixing using known methods and apparatuses.

[0048] <Continuous reinforcing fiber> The continuous reinforcing fiber used for the liner of the present invention is a reinforcing fiber having a fiber length exceeding 100 mm. Examples of the shape of the continuous reinforcing fiber include tows, sheets, tapes, etc. Examples of the continuous reinforcing fiber constituting the sheet or tape include unidirectional (UD) materials, woven fabrics, non-woven fabrics, etc. From the viewpoint of molding the liner of the present invention by the braiding method, winding method, etc. described later, the shape of the continuous reinforcing fiber is preferably a tow or a tape, and more preferably a tow (continuous reinforcing fiber bundle). The number of fiber bundles (filament number) constituting the tow is preferably 3K to 50K, more preferably 6K to 40K, from the viewpoint of easily obtaining high strength and high elastic modulus.

[0049] There is no particular limitation on the average fiber length of the continuous reinforcing fiber bundle, but from the viewpoint of moldability, it is preferably 1 to 10,000 m, more preferably 100 to 10,000 m. The average fineness of the continuous reinforcing fiber bundle is preferably 50 to 2000 tex (g / 1000 m), more preferably 200 to 1500 tex, still more preferably 500 to 1500 tex, from the viewpoints of moldability and easily obtaining high strength and high elastic modulus. The average tensile elastic modulus of the continuous reinforcing fiber bundle is preferably 50 to 1000 GPa.

[0050] Examples of the types of continuous reinforcing fibers include inorganic fibers such as glass fibers, carbon fibers, metal fibers, boron fibers, basalt fibers, and ceramic fibers; and organic fibers such as aramid fibers, polyoxymethylene fibers, aromatic polyamide fibers, polyparaphenylene benzobisoxazole fibers, and ultra-high molecular weight polyethylene fibers. Among these, from the viewpoint of obtaining high strength, inorganic fibers are preferred as the continuous reinforcing fibers, and at least one selected from the group consisting of glass fibers, carbon fibers, and basalt fibers is more preferred because of their light weight, high strength, and high elastic modulus, and carbon fibers are even more preferred. Examples of the carbon fibers include polyacrylonitrile-based carbon fibers and pitch-based carbon fibers. In addition, carbon fibers derived from plant-derived raw materials such as lignin and cellulose can also be used.

[0051] The continuous reinforcing fibers used in the present invention may be those treated with a treatment agent. Examples of the treatment agent include a surface treatment agent or a sizing agent. As the above surface treatment agent, a silane coupling agent is preferred. Examples of the silane coupling agent 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.

[0052] Examples of the above sizing agent include, for example, 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 one or more of these can be used in combination. Examples of the sizing agent combined with two or more types include, for example, urethane / epoxy-based sizing agents, urethane / acrylic-based sizing agents, and urethane / carboxylic acid-based sizing agents.

[0053] Among these, from the viewpoint of improving the interfacial adhesiveness with a cured product of a thermosetting resin, particularly an epoxy resin composition, and further improving the strength and impact resistance of the resulting liner, the continuous reinforcing fiber is preferably treated with one or more selected from the group consisting of a urethane-based sizing agent, an epoxy-based sizing agent, and a urethane / epoxy-based sizing agent, and more preferably treated with an epoxy-based sizing agent.

[0054] From the viewpoint of improving the interfacial adhesiveness with a cured product of a thermosetting resin or a thermosetting resin composition and further improving the strength and impact resistance of the resulting liner, the amount of the treatment agent is preferably 0.001 to 5% by mass, more preferably 0.1 to 3% by mass, and still more preferably 0.5 to 2% by mass based on the continuous reinforcing fiber.

[0055] Commercially available products can also be used as the continuous reinforcing fiber. Examples of commercially available products of carbon fiber as the continuous reinforcing fiber include, for example, Torayca yarns "T300", "T300B", "T400HB", "T700SC", "T800SC", "T800HB", "T830HB", "T1000GB", "T100GC", "M35JB", "M40JB", "M46JB", "M50JB", "M55J", "M55JB", "M60JB", "M30SC", "Z600" series, Torayca cloth "CO6142", "CO6151B", "CO6343", "CO6343B", "CO6347B", "CO6644B", "CK6244C", "CK6273C", "CK6261C", "UT70" series, "UM46" series, "BT70" series, etc.

[0056] The content of the continuous reinforcing fiber in the liner of the present invention is not particularly limited, but from the viewpoint of obtaining high strength and high elastic modulus, the volume fraction (Vf) of the continuous reinforcing fiber is preferably 10% or more, more preferably 20% or more, still more preferably 30% or more, and even more preferably 40% or more. Also, from the viewpoints of gas barrier properties and impact resistance, the volume fraction is preferably 98% or less, more preferably 95% or less, still more preferably 80% or less, and even more preferably 70% or less. The volume fraction (Vf) of the continuous reinforcing fibers in the liner can be calculated from the following formula. Vf = {mass (g) of continuous reinforcing fibers in the liner / specific gravity of continuous reinforcing fibers} ÷ {mass (g) of the liner / specific gravity of the liner} × 100

[0057] Although the liner of the present invention is composed of a fiber-reinforced composite material, optional layers such as a protective layer, a paint layer, a rust preventive-containing layer, etc. can be provided as necessary. However, from the viewpoint of obtaining the effects of the present invention, the total content of the cured product of the thermosetting resin or thermosetting resin composition and the continuous reinforcing fibers in the liner of the present invention is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and the upper limit is 100% by mass.

[0058] [Method for manufacturing a liner for a pressure vessel] The method for manufacturing a liner for a pressure vessel of the present invention (hereinafter, also simply referred to as "the manufacturing method of the present invention") is not particularly limited. For example, a method of molding using a prepreg composed of the thermosetting resin or thermosetting resin composition and continuous reinforcing fibers by a braiding method, a winding method, a 3D printer method, etc. can be mentioned. From the viewpoints of molding a liner having the above-described twisted structure or spiral structure, molding the cylindrical portion and at least one dome portion of the liner in one batch, and productivity, the method for manufacturing a liner for a pressure vessel of the present invention preferably has a step of molding a tow prepreg composed of a thermosetting resin or thermosetting resin composition and a continuous reinforcing fiber bundle using a braiding method or a winding method. From the viewpoint that it is also possible to mold a liner without using a mandrel or the like, it is more preferable to use a braiding method.

[0059] The tow prepreg is obtained by impregnating the continuous reinforcing fiber bundle with the thermosetting resin or thermosetting resin composition. As the thermosetting resin or thermosetting resin composition, it is preferable to use the above-described epoxy resin composition, and from the viewpoint of enhancing the impregnation property into the continuous reinforcing fiber bundle, it is more preferable that the composition contains a solvent.

[0060] The method of impregnating a continuous reinforcing fiber with a thermosetting resin or a thermosetting resin composition is not particularly limited, and known methods can be used. For example, there is a method in which a continuous reinforcing fiber bundle unwound from a roll is immersed in a resin bath filled with a thermosetting resin or a thermosetting resin composition to impregnate the thermosetting resin or the thermosetting resin composition, and then pulled up from the resin bath. Thereafter, a step of removing the excess thermosetting resin or thermosetting resin composition using a squeezing roll or the like may be performed. The impregnation of the thermosetting resin or the thermosetting resin composition can also be carried out under pressure conditions or reduced pressure conditions as necessary. When the thermosetting resin composition contains a solvent, then the continuous reinforcing fiber impregnated with the thermosetting resin composition is subjected to a drying step to remove the solvent. The drying conditions in the drying step are not particularly limited, but it is preferable that the solvent can be removed and the curing of the thermosetting resin in the composition does not proceed excessively. From this viewpoint, for example, the drying temperature can be selected in the range of 30 to 100°C, and the drying time can be selected in the range of 10 seconds to 5 minutes. The above drying step can be carried out by a known method using a hot air dryer, a heater, a heating roll, a hot plate, etc. For example, a method of running in a heating atmosphere by a hot air dryer, a heater, etc.; a method of contacting a heating body such as a heating roll, a hot plate; etc. Among these, the method using a hot air dryer is preferable.

[0061] The obtained tow prepreg may be wound around a bobbin once, but from the viewpoint of improving productivity, it is preferable to continuously supply it to the braiding method or the winding method without winding.

[0062] The forming by the braiding method and the winding method using the tow prepreg can be carried out by a known method using a braider or a winding device. When using the braiding method, for example, a mandrel made of metal or the like is used, and the tow prepreg is braided by a braider so as to be in a unidirectional or a braided structure to form a prepreg having a cylindrical shape or a shape in which one or both ends thereof are sealed by a dome portion. Next, a step of heating the prepreg to cure the thermosetting resin is performed. The heating is performed by a known method at a temperature and for a time sufficient to cure the thermosetting resin contained in the prepreg. From the viewpoint of improving productivity, the heating temperature is preferably in the range of 80 to 140 ° C, more preferably 80 to 120 ° C, and the heating time is preferably in the range of 10 minutes to 5 hours. In addition, in the braiding method, it is also possible to form a prepreg having a cylindrical shape or a shape in which one or both ends thereof are sealed by a dome portion by braiding the tow prepreg without using a mandrel.

[0063] When using the winding method, for example, using a winding device, the tow prepreg is spirally wound around the outer surface of a mandrel made of metal or the like to form a prepreg having a cylindrical shape or a shape in which one or both ends thereof are sealed by a dome portion. Next, a step of heating the prepreg in the same manner as described above to cure the thermosetting resin is performed.

[0064] When a member in which only the cylindrical portion of the liner or only one end of the liner cylindrical portion is sealed is formed by the braiding method and the winding method, a separately produced dome portion is joined and sealed to one or both ends of the cylindrical portion to manufacture the liner of the present invention.

[0065] The liner of the present invention is a liner for a pressure vessel, and from the viewpoint of the effectiveness of the present invention, the pressure vessel is preferably a high-pressure gas storage tank. The gas to be stored in the high-pressure gas storage tank may be a gas at 25 ° C and 1 atm, and examples thereof include hydrogen, oxygen, carbon dioxide, nitrogen, argon, LPG, alternative freon, methane and the like. Among these, from the viewpoint of the effectiveness of the present invention, hydrogen is preferred.

[0066] [High-pressure gas storage tank] The high-pressure gas storage tank of the present invention includes the liner for the pressure vessel. By including the liner for the pressure vessel, the high-pressure gas storage tank of the present invention has good gas barrier properties for gases such as hydrogen gas, and is also excellent in light weight, pressure resistance, and impact resistance. The main body of the high-pressure gas storage tank of the present invention may be composed only of the liner for the pressure vessel, or may include the liner for the pressure vessel and an outer layer for reinforcing the liner. Since the liner of the present invention is excellent in pressure resistance and impact resistance, even when an outer layer is further provided, it is possible to reduce its thickness.

[0067] The high-pressure gas storage tank having the liner and the outer layer of the present invention will be described with reference to FIG. 5. FIG. 5 is a schematic cross-sectional view showing an embodiment of the high-pressure gas storage tank of the present invention. The high-pressure gas storage tank 200 has a liner 100' and an outer layer 4. The outer layer 4 is formed so as to cover the outer surface of the liner 100' without any gaps.

[0068] The outer layer 4 is not particularly limited as long as it can reinforce the liner 100'. From the viewpoints of gas barrier properties and impact resistance for gases such as hydrogen gas, the outer layer 4 is preferably composed of a fiber-reinforced composite material. As the fiber-reinforced composite material constituting the outer layer 4, the same material as the fiber-reinforced composite material constituting the liner 100' can be used.

[0069] The thickness of the outer layer can be appropriately selected according to the capacity, shape, etc. of the high-pressure gas storage tank. 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 still more preferably 400 μm or more. From the viewpoint of miniaturization and weight reduction of the high-pressure gas storage tank, it is preferably 80 mm or less, more preferably 60 mm or less.

[0070] The outer layer 4 may be provided directly on the outer surface of the liner 100'. Alternatively, one or more other layers may be provided on the outer surface of the liner, and it may be provided on the surface of the other layer. For example, in order to improve the adhesion between the liner and the outer layer, an adhesive layer may be provided between the liner and the outer layer. Also, an arbitrary layer such as a protective layer, a paint layer, a rust preventive-containing layer, etc. may be formed on the surface of the outer layer 4.

[0071] The base 5 is, for example, substantially cylindrical, and is fitted and fixed between the liner 100' and the outer layer 4. The substantially cylindrical opening of the base 5 functions as the opening of the high-pressure gas storage tank 200. The base 5 may be made of other metals such as stainless steel and aluminum, or may be made of resin. The boss 6 is made of, for example, aluminum, and is assembled with a part of it exposed to the outside, and functions to conduct the heat generation and heat absorption inside the tank to the outside. The valve 7 is, for example, in a shape in which male threads are formed on a cylindrical portion, and is screwed into female threads formed on the inner surface of the base 5, so that the opening of the base 5 is closed by the valve 7. In the high-pressure gas storage tank of the present invention, the base 5, the boss 6, and the valve 7 can also be replaced by other means.

[0072] Note that the high-pressure gas storage tank in which the main body is composed only of the liner of the present invention can have the same configuration as the high-pressure gas storage tank shown in FIG. 5 except that the outer layer 4 is provided. Alternatively, the base 5 and the valve 7 can be attached to the opening 3 of the liner 100 shown in FIGS. 1 and 2 and used as a high-pressure gas storage tank.

Example

[0073] Next, the present invention will be specifically described by way of examples. However, the present invention is not limited by these examples in any way. The measurements and evaluations in this example were performed by the following methods.

[0074] <Hydrogen gas permeation coefficient [cc 3 ·cm / (cm2 ·s·cmHg)]> The epoxy resin composition prepared in the production example was applied to a smooth metal plate coated with a release agent using a bar coater to a thickness of 100 μm and a size of 200 mm square, and then heated at 100 °C for 5 minutes to cure, thereby producing a cured product. Using this cured product, a hydrogen gas permeation coefficient was measured in a dry state at 23 °C using a vapor transmission rate measuring device ("G2700T·F" manufactured by GTR Tech Co., Ltd.).

[0075] <Glass transition temperature> The glass transition temperature Tg of the cured product of the epoxy resin composition used in the liner produced in each example was measured using a differential scanning calorimeter device ("DSC25" manufactured by TA Instruments). Under a nitrogen atmosphere, a heat history under the following conditions was imposed on about 5 mg of a sample (epoxy resin composition). The conditions of the heat history were the first heating (heating rate 10 °C / min), then cooling (cooling rate 10 °C / min), and then the second heating (heating rate 10 °C / min). The heating temperature was from room temperature to 225 °C, and the peak temperature of the glass transition temperature observed during the second heating was read and shown in Table 1.

[0076] <Tensile strength> Using a plate made of the same material as the fiber-reinforced composite material constituting the liner produced in each example, a Type 1A test piece defined in JIS K7161-2:2014 was prepared and used for measurement. Using a tensile testing machine ("AGX-100kNplus" manufactured by Shimadzu Corporation), a tensile test was conducted in accordance with JIS K7161-1:2014 and K7161-2:2014 at a temperature of 23 °C, a grip distance of 50 mm, and a test speed of 1 mm / min to measure the tensile strength.

[0077] Production Example 1 (Preparation of epoxy resin curing agent solution A) 1 mol of metaxylylenediamine (MXDA) was charged into a reaction vessel. The temperature was raised to 60 °C under a nitrogen stream, and 0.93 mol of methyl acrylate was added dropwise over 1 hour. While distilling off the generated methanol, the temperature was raised to 165 °C and maintained at 165 °C for 2.5 hours to obtain an epoxy resin curing agent, which is a reaction product of MXDA and methyl acrylate. Methanol was added dropwise thereto over 1.5 hours to obtain an epoxy resin curing agent solution A in which the epoxy resin curing agent was 65% by mass and methanol was 35% by mass. (Preparation of Epoxy Resin Composition 1) To 14.4 g of the obtained epoxy resin curing agent solution A, 1.5 g of methanol as a solvent, 9.9 g of ethyl acetate, and 4.5 g of an epoxy resin having a glycidylamino group derived from metaxylylenediamine (「TETRAD-X」manufactured by Mitsubishi Gas Chemical Company, Inc.) (active amine hydrogens in the epoxy resin curing agent / number of epoxy groups in the epoxy resin = 1.2) were added and stirred to prepare Epoxy Resin Composition 1 having a solid content concentration of 40% by mass. The hydrogen gas permeation coefficient of the cured product of Epoxy Resin Composition 1 measured by the above method was 3.9×10 -11 [cc 3 ·cm / (cm 2 ·s·cmHg)].

[0078] Example 1 (Production of Liner for Pressure Vessel and High-Pressure Gas Storage Tank) A liner for a pressure vessel and a high-pressure gas storage tank were produced in the following manner. [Production of Cylindrical Portion of Liner] Epoxy Resin Composition 1 obtained in Production Example 1 was used as the thermosetting resin composition, and continuous carbon fiber 「TORAYCA T800SC-24000」(number of filaments: 24,000, linear density: 1,030 tex, tensile modulus of elasticity: 294 GPa) manufactured by Toray Industries, Inc. was used as the continuous reinforcing fiber. After impregnating the continuous carbon fiber with the epoxy resin composition 1, it was dried by heating in a hot air dryer at 80°C for 80 seconds to produce a tow prepreg. Next, by the braiding method, the tow prepreg was braided on a metal mandrel with a diameter of 250 mm and a length of 1200 mm to form a braided structure as shown in Fig. 3, and a cylindrical prepreg with an outer diameter of 300 mm, a length of 1000 mm, and a thickness of 25 mm was produced. After heat-curing this cylindrical prepreg on the metal mandrel at 120°C for 30 minutes, the metal mandrel was removed to produce a liner cylindrical part 1 composed of a carbon fiber reinforced composite material as shown in Figs. 1 and 2. The volume fraction (Vf) of the continuous carbon fiber in the liner cylindrical part 1 was 55%. 〔Fabrication of the dome part of the liner〕 Epoxy resin composition 1 obtained in Production Example 1 was used as the thermosetting resin composition, and continuous carbon fiber "Trekacros UT70-30G" (unidirectional cross, sheet thickness 0.167 mm) manufactured by Toray Industries, Inc. was used as the continuous reinforcing fiber. After impregnating the continuous carbon fiber with the epoxy resin composition 1, it was dried by heating in a hot air dryer at 80°C for 80 seconds to produce a prepreg. Next, using a mold, by the hot press molding method, a hollow dome part 21 having an opening with a diameter of 50 mm and a hollow dome part 22 without an opening, both having the shapes shown in Figs. 1 and 2, were produced at a press pressure of 0.5 MPa, a press temperature of 140°C, and a press time of 120 minutes. The dome parts 21 and 22 had an outer diameter of 300 mm, a dome part height of 125 mm, and a thickness of 25 mm, and the volume fraction (Vf) of the continuous carbon fiber was 55%. 〔Fabrication of the liner and the high-pressure gas storage tank〕 The dome parts 21 and 22 were respectively joined to both ends of the liner cylindrical part 1 obtained by the above method with bolts to obtain a liner 100 as shown in Figs. 1 and 2. Further, on the outer surface of the liner 100, the same tow prepreg as that used for the production of the cylindrical part of the liner was wound by the filament winding method and heated at 120°C for 240 minutes to form an outer layer with a thickness of 60 mm, thereby obtaining a high-pressure gas storage tank.

[0079] Example 2 (Fabrication of a liner for a pressure vessel and a high-pressure gas storage tank) A tow prepreg was produced in the same manner as in Example 1. Then, by the braiding method, the tow prepreg was braided on a metal mandrel with a diameter of 250 mm and a length of 1200 mm to form a braided structure as shown in FIG. 3, and a prepreg having a shape in which one end of the cylindrical portion was sealed by a hollow dome portion was produced. The prepreg cylindrical portion had an outer diameter of 300 mm, a length of 1000 mm, and a thickness of 25 mm, and the dome portion of the prepreg had an outer diameter of 300 mm, a dome portion height of 125 mm, and a thickness of 25 mm. After heating and curing this prepreg on the metal mandrel at 120 °C for 30 minutes, the metal mandrel was removed to produce a member in which one end of the liner cylindrical portion 1 was sealed by the dome portion 22. The volume fraction (Vf) of continuous carbon fibers in the member was 55%. Next, in the same manner as in Example 1, a hollow dome portion 21 having an outer diameter of 300 mm, a dome portion height of 125 mm, a thickness of 25 mm, and an opening with a diameter of 50 mm was produced, and it was joined to the member with bolts to obtain a liner 100. Further, an outer layer was formed on the outer surface of the liner 100 in the same manner as in Example 1 to obtain a high-pressure gas storage tank.

[0080] Table 1 shows the results of measuring the glass transition temperature of the cured epoxy resin and the tensile strength of the fiber-reinforced composite material for the cured epoxy resin and the fiber-reinforced composite material constituting the liner cylindrical portion obtained in Example 1 and Example 2 by the above method. In Table 1, instead of the fiber-reinforced composite materials used in Example 1 and Example 2, the glass transition temperature and tensile strength of polyethylene resin (「UF420」manufactured by Nippon Polyethylene Co., Ltd.), which is a thermoplastic resin, were measured by the above method, and the results are shown together (Reference Example 1).

[0081]

Table 1

Industrial Applicability

[0082] According to the present invention, it is possible to provide a liner for a pressure vessel that has light weight, gas barrier properties such as hydrogen gas, heat resistance, and high strength, and is also excellent in productivity. Since the liner for a pressure vessel of the present invention has high gas barrier properties, heat resistance, and strength, it can be used directly as a pressure vessel such as a high-pressure gas storage tank without providing an outer layer. The high-pressure gas storage tank equipped with the liner for a pressure vessel is suitable as a vehicle-mounted high-pressure gas storage tank, and because it is lightweight, it is possible to improve the fuel efficiency of the vehicle on which it is mounted.

Explanation of Reference Numerals

[0083] 100, 100’ Liners for pressure vessels 1 Cylindrical portion 1a, 1b Ends of the cylindrical portion 21, 22 Dome portions 3 Opening 10 Fiber-reinforced composite material 11 Cured product of tow prepreg 200 High-pressure gas storage tank 4 Outer layer 5 Base 6 Boss 7 Valve

Claims

A high-pressure gas storage tank comprising a liner for a pressure vessel composed of a cured product of a thermosetting resin composition and a continuous reinforcing fiber, wherein the thermosetting resin composition is an epoxy resin composition containing an epoxy resin (A) and an epoxy resin curing agent (B) containing a reaction product (X) of the following component (x1) and component (x2), the high-pressure gas is hydrogen gas, a high-pressure gas storage tank. (x1) At least one selected from the group consisting of metaxylylenediamine and paraxylylenediamine (x2) At least one selected from the group consisting of an unsaturated carboxylic acid represented by the following general formula (1) and its derivatives 【Chemical 1】 (In formula (1), R1 and R2 each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms.)

2. The high-pressure gas storage tank according to claim 1, wherein the fiber-reinforced composite material constituting the liner has a braided structure or a helical structure.

3. The high-pressure gas storage tank according to claim 1 or 2, having a cylindrical portion and two dome portions for sealing both ends of the cylindrical portion.

4. The high-pressure gas storage tank according to claim 3, wherein the cylindrical portion and at least one of the dome portions are integrally molded.

5. The high-pressure gas storage tank according to any one of claims 1 to 4, wherein the epoxy resin (A) is mainly composed of an epoxy resin having a glycidylamino group derived from metaxylylenediamine.

6. The high-pressure gas storage tank according to any one of claims 1 to 5, wherein the continuous reinforcing fiber is at least one selected from the group consisting of glass fiber, carbon fiber, and basalt fiber.

7. The method for manufacturing the liner for a pressure vessel has a step of molding a tow prepreg composed of the thermosetting resin composition and a continuous reinforcing fiber bundle using a braiding method or a winding method. The method for manufacturing a high-pressure gas storage tank according to any one of claims 1 to 6.

Images