JP6202978B2 - Fiber-reinforced composite material and pressure vessel using the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a fiber reinforced composite material and a pressure vessel, and more specifically, a fiber reinforced composite material obtained by impregnating a reinforcing fiber with an epoxy resin composition containing a specific rubber-modified epoxy resin, and the use thereof for a reinforcing layer. It is related with the pressure vessel obtained.

  Epoxy resins have excellent adhesion to various substrates, and cured products obtained by curing epoxy resins with curing agents have relatively good heat resistance, chemical resistance, electrical properties, mechanical properties, etc. Therefore, it is used for a wide range of applications such as paints, adhesives, and various molding materials.

  For example, an epoxy resin is used as a matrix resin in a fiber-reinforced composite material obtained by impregnating a matrix resin into a reinforcing fiber. Patent Document 1 proposes a specific epoxy resin composition for fiber-reinforced composite materials comprising an epoxy resin, dicyandiamide and a curing accelerator. However, the epoxy resin composition has a problem that the reinforcing effect on the fiber is insufficient because the impregnation property to the reinforcing fiber is insufficient and the flexibility is insufficient.

  Moreover, the fiber reinforced composite material is used, for example in formation of a reinforcement layer in a pressure vessel (for example, refer patent document 2). The fiber reinforced composite material used for the reinforcing layer of the pressure vessel is required to have excellent strength that can withstand the pressure in the vessel, specifically, excellent tensile strength in the direction perpendicular to the fiber orientation in the material.

Japanese Patent No. 3867377 JP 2007-107557 A

  Accordingly, an object of the present invention is to provide a fiber-reinforced composite material having a good reinforcing effect and excellent tensile strength in the direction perpendicular to the fiber orientation in the material.

  As a result of intensive studies, the present inventors have obtained a fiber-reinforced composite material obtained by impregnating reinforcing fibers with a resin composition containing a specific rubber-modified epoxy resin, a curing agent for epoxy resin and a curing accelerator, The inventors have found that the above object can be achieved, and have reached the present invention.

That is, the present invention relates to an epoxy resin composition containing (A) 100 parts by mass of a rubber-modified epoxy resin, (B) 50 to 150 parts by mass of an epoxy resin curing agent, and (C) 0.1 to 5 parts by mass of a curing accelerator. (A) a rubber-modified epoxy resin is reacted with (a) an aromatic epoxy resin that is liquid at room temperature and (b) a nitrile butadiene rubber containing a terminal carboxyl group that is liquid at room temperature. The present invention provides a fiber-reinforced composite material characterized by comprising a reaction product as a main component.
Further, the present invention provides a pressure vessel having an airtight liner and a reinforcing layer formed of a fiber reinforced composite material that reinforces the outside of the liner, wherein the fiber reinforced composite material comprises (A) to (C The pressure vessel is characterized by being the above-mentioned fiber-reinforced composite material obtained by impregnating reinforcing fibers with an epoxy resin composition containing the component.

  The fiber-reinforced composite material of the present invention has a good reinforcing effect and an excellent tensile strength in the direction perpendicular to the fiber orientation in the material. Moreover, since the pressure vessel of the present invention obtained by using the fiber-reinforced composite material of the present invention for the reinforcing layer can reduce the amount of material used by using a material having excellent strength, the pressure vessel is lightweight and excellent in strength. Become.

FIG. 1 is a schematic view showing a rotating mold (mandrel) used for manufacturing a fiber-reinforced composite material by a filament winding method in Examples and Comparative Examples. FIG. 2A is an optical micrograph (magnification 20) of a cut surface obtained by cutting the specimen of the fiber-reinforced composite material produced in Example 1 in a direction orthogonal to the reinforcing fiber, and FIG. 2 (a) is an enlarged photograph (magnification 100). FIG. 3A is an optical micrograph (magnification 20) of a cut surface obtained by cutting the specimen of the fiber-reinforced composite material manufactured in Comparative Example 1 in a direction orthogonal to the reinforcing fiber, and FIG. 3A is an enlarged photograph (magnification 100). FIG. 4A is an optical micrograph (magnification 20) of a cut surface obtained by cutting the specimen of the fiber-reinforced composite material produced in Comparative Example 2 in a direction orthogonal to the reinforcing fiber, and FIG. It is an enlarged photograph (magnification 100) of 4 (a).

Hereinafter, the fiber-reinforced composite material of the present invention will be described in detail.
The (A) rubber-modified epoxy resin used in the fiber-reinforced composite material of the present invention comprises: (a) an aromatic epoxy resin that is liquid at room temperature; and (b) a nitrile butadiene rubber containing a terminal carboxyl group that is liquid at room temperature. The obtained reaction product is the main component.
The content of the main component composed of the reaction product is preferably 5 to 70% by mass, more preferably 10 to 50% by mass in the (A) rubber-modified epoxy resin. (A) The rubber-modified epoxy resin preferably contains a diluent having a reactive group as an optional component, as described later, in addition to the main component. Content of the arbitrary component with respect to the main component which consists of the said reaction material is as below-mentioned.

Examples of the aromatic epoxy resin that is liquid at room temperature as the component (a) used in the present invention include polyglycidyl ether compounds of mononuclear polyhydric phenol compounds such as hydroquinone, resorcin, pyrocatechol, and phloroglucinol; Dihydroxynaphthalene, biphenol, methylene bisphenol (bisphenol F), methylene bis (orthocresol), ethylidene bisphenol, isopropylidene bisphenol (bisphenol A), isopropylidene bis (orthocresol), tetrabromobisphenol A, 1,3-bis (4- Hydroxycumylbenzene), 1,4-bis (4-hydroxycumylbenzene), 1,1,3-tris (4-hydroxyphenyl) butane, 1,1,2,2-tetra (4-hydroxyphenyl) D Polyglycidyl ether compounds of polynuclear polyhydric phenol compounds such as thiobisphenol, sulfobisphenol, oxybisphenol, phenol novolak, orthocresol novolak, ethylphenol novolak, butylphenol novolak, octylphenol novolak, resorcin novolak, terpene phenol, etc. . The term “liquid at room temperature” here means more specifically liquid at 23 ° C.
Among these, the component (a) is preferably a polyglycidyl ether compound of isopropylidene bisphenol (bisphenol A), that is, a bisphenol A type epoxy resin, from the viewpoint of low temperature reactivity, strength, and chemical resistance.

  Commercially available products can be used as the terminal carboxyl group-containing nitrile butadiene rubber that is liquid at room temperature, which is the component (b) used in the present invention, and examples of commercially available products include CTBN series manufactured by CVC Thermoset Specialities. . The nitrile butadiene rubber containing a terminal carboxyl group that is liquid at room temperature as component (b) has a nitrile content of 10 to 30%; a carboxyl group equivalent of 1000 to 2000; a number average molecular weight of 2500 to 4000, The compatibility with the aromatic epoxy resin that is liquid at room temperature, which is the component (a), is good, and particularly high flexibility performance can be imparted. The term “liquid at room temperature” here means more specifically liquid at 23 ° C.

  The reaction product of the component (a) and the component (b) constituting the rubber-modified epoxy resin (A) used in the present invention is, for example, (a) an aromatic epoxy resin that is liquid at room temperature and (b ) It can be easily obtained by reacting a terminal carboxyl group-containing nitrile butadiene rubber that is liquid at room temperature at 100 to 160 ° C. for 3 to 6 hours in the presence of a catalyst such as triphenylphosphine. The reaction is preferably performed at a reaction ratio of 5 to 100 parts by mass of component (b) with respect to 100 parts by mass of component (a).

  For the rubber-modified epoxy resin constituting the component (A) used in the present invention, a diluent having a reactive group can be further used. When the diluent is used, an effect of improving workability can be obtained. As for the usage-amount of this diluent, 20-500 mass parts is preferable with respect to 100 mass parts of reaction materials of (a) component and (b) component.

  Examples of the reactive group possessed by the diluent include a glycidyl group and a hydroxyl group. Examples of the diluent include IPU-22G (manufactured by Okamura Oil Co., Ltd.) and SB-20G (manufactured by Okamura Oil Co., Ltd.) which are liquid bisphenol F type epoxy resin, tertiary carboxylic acid glycidyl ester, and higher dibasic acid diglycidyl ester. Glycidyl esters such as dimer acid diglycidyl ester, phenyl glycidyl ether, cresyl glycidyl ether, Pt-butylphenol glycidyl ether, and aromatic glycidyl ethers. Among these, from the viewpoint of reactivity and dilution efficiency, it is preferable to use liquid bisphenol F type epoxy resin and / or tertiary carboxylic acid glycidyl ester, and in particular, a reaction product of component (a) and component (b). The liquid bisphenol F type epoxy resin 20 to 300 parts by mass (particularly 40 to 250 parts by mass) and / or the tertiary carboxylic acid glycidyl ester 30 to 150 parts by mass (particularly 50 to 100 parts by mass) are used for 100 parts by mass. It is preferable. The liquid bisphenol F type epoxy resin is preferably liquid at room temperature (23 ° C.).

  When a diluent having a reactive group is used, a reaction product is obtained by reacting the component (a) and the component (b), and then the diluent is added and mixed therein, and the resulting mixture is mixed. (A) What is necessary is just to use as rubber-modified epoxy resin. When adding and mixing this diluent to the reaction product of component (a) and component (b), it is preferable to mix at 70 to 130 ° C. for 0.5 to 10 hours.

Examples of the curing agent for epoxy resin that is the component (B) used in the present invention include an acid anhydride type curing agent and a polyamine type curing agent.
Examples of the acid anhydride type curing agent include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, 4-methyl-tetrahydrophthalic anhydride, hexahydrophthalic anhydride. Acid anhydrides such as maleic anhydride, succinic anhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride Can be mentioned.
Examples of the polyamine type curing agent include aliphatic polyamines such as ethylenediamine, diethylenetriamine, and triethylenetetramine; mensendiamine, isophoronediamine, bis (4-amino-3-methylcyclohexyl) methane, bis (aminomethyl) cyclohexane, 3 , 9-bis (3-aminopropyl) 2,4,8,10-tetraoxaspiro [5,5] undecane and other alicyclic polyamines; m-xylenediamine and other aliphatic amines having an aromatic ring, m- Phenylenediamine, 2,2-bis (4-aminophenyl) propane, diaminodiphenylmethane, diaminodiphenylsulfone, α, α-bis (4-aminophenyl) -p-diisopropylbenzene, 2,2-bis (4-aminophenyl) ) -1,1,1,3,3,3-hexafluo Aromatic polyamines such as lopropane; 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl 2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 2,4-diamino-6 (2′-methylimidazole (1 ′ )) Ethyl-s-triazine, 2,4-diamino-6 (2′-undecylimidazole (1 ′)) ethyl-s-triazine, 2,4-diamino-6 (2′-ethyl, 4-methylimidazole) (1 ′)) Ethyl-s-triazine, 2,4-diamino-6 (2′-methyl) Ruimidazole (1 ′)) ethyl-s-triazine isocyanuric acid adduct, 2-methylimidazole isocyanuric acid 2: 3 adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-3,5-dihydroxymethyl Various imidazoles such as imidazole, 2-phenyl-4-hydroxymethyl-5-methylimidazole, 1-cyanoethyl-2-phenyl-3,5-dicyanoethoxymethylimidazole, and imidazoles and phthalic acid, isophthalic acid, terephthalic acid Imidazole compounds such as acids, trimellitic acid, pyromellitic acid, naphthalenedicarboxylic acid, maleic acid, salts with polyvalent carboxylic acids such as succinic acid; triazole compounds such as 2-phenyl-4-hydroxy-5-methyltriazole, etc. Examples include polyamine compounds That.
As the component (B), among these curing agents for epoxy resins, acid anhydride type curing agents are preferable from the viewpoint of long pot life and chemical resistance.

  In the epoxy resin composition used for the fiber-reinforced composite material of the present invention, the content of the (B) epoxy resin curing agent is 50 to 150 parts by mass with respect to 100 parts by mass of the (A) rubber-modified epoxy resin, Preferably it is 70-100 mass parts. If it is less than 50 parts by mass, curing will be insufficient, and if it exceeds 150 parts by mass, the strength will be insufficient.

  Examples of the curing accelerator as the component (C) used in the present invention include trimethylamine, ethyldimethylamine, propyldimethylamine, N, N′-dimethylpiperazine, pyridine, picoline, 1,8-diazabiscyclo (5,5). 4,0) Undecene-1 (DBU), dimethylbenzylamine, 2- (dimethylaminomethyl) phenol (DMP-10), 2,4,6-tris (dimethylaminomethyl) phenol (DMP-30), etc. Triamines; phenols such as phenol novolak, o-cresol novolak, p-cresol novolak, t-butylphenol novolak, dicyclopentadiene cresol; p-toluenesulfonic acid, 1-aminopyrrolidine salt of thiocyanic acid (Otsuka Chemical Co., Ltd.) ); NR-S), triphenylphenol Sphine, methyltributylphosphonium dimethyl phosphate (manufactured by Nippon Chemical Industry Co., Ltd .; Hishicolin PX-4MP), tetra-n-butylphosphonium benzotriazolate (manufactured by Nippon Chemical Industry Co., Ltd .; Hishicolin PX-4BT), Tetra-n-butylphosphonium O, O-diethylphosphorosiate (manufactured by Nippon Chemical Industry Co., Ltd .; Hishicolin PX-4ET), tetra-n-butylphosphonium tetraphenylborate (Nippon Chemical Industry Co., Ltd.) And phosphonium salts such as Hishicolin PX-4PB). Among these, tertiary amines are preferable, and dimethylbenzylamine is more preferable.

  In the epoxy resin composition used for the fiber-reinforced composite material of the present invention, the content of the curing accelerator (C) is 0.1 to 5 masses per 100 mass parts of the (A) rubber-modified epoxy resin. Part, preferably 0.3 to 3 parts by mass. If the amount is less than 0.1 parts by mass, the problem that the curing rate becomes slow is caused.

  Here, it is preferable that the epoxy resin composition containing the components (A) to (C) has a mixed viscosity of 2000 mPa · s or less at 25 ° C. because the reinforcing fibers are easily impregnated. This is because, in order to suppress the increase in the viscosity of the epoxy resin composition and sufficiently impregnate the reinforcing fiber, it is preferable to carry out the process at a temperature of 25 to 50 ° C. This is because it is easy to impregnate the reinforcing fiber. The mixed viscosity is more preferably 500 to 1000 mPa · s at 25 ° C. Adjustment of mixing viscosity can be performed by selecting suitably the kind and content of (A)-(C) component, for example. In the present invention, the mixed viscosity is measured with a B-type viscometer by measuring an epoxy resin composition which is a mixture of the component (A), the component (B) and the component (C) and the additives used as necessary. Value.

  In addition, since the epoxy resin composition containing the components (A) to (C) has a curing temperature of 100 ° C. or less, an uncrosslinked portion is present, a stress relaxation action works, and ductility is improved. preferable. The curing temperature is preferably 80 ° C. or higher. Adjustment of hardening temperature can be performed by selecting suitably the kind and content of (A)-(C) component, for example.

  On the other hand, examples of the reinforcing fiber used in the fiber-reinforced composite material of the present invention include glass fiber, carbon fiber, aramid fiber, boron fiber, alumina fiber, and silicon carbide fiber. Among these, glass fiber is preferable from the viewpoint of being easily available on the market and inexpensive, and carbon fiber is preferable from the viewpoint of light weight and high strength.

  The fiber-reinforced composite material of the present invention is obtained by impregnating reinforcing fibers with an epoxy resin composition containing the components (A) to (C). When the reinforcing fiber is impregnated with the epoxy resin composition, the volume content of the epoxy resin composition in the fiber reinforced composite material is desirably 25% to 45%, particularly 30% to 40%.

The fiber reinforced composite material of the present invention can be produced by the same method as that of a conventional fiber reinforced composite material. As a method for producing a fiber-reinforced composite material of the present invention, a filament winding method can be cited as a method for forming a fiber-reinforced composite material that has excellent strength characteristics and excellent productivity.
This filament winding method is a method in which a roving continuously impregnated with resin in a resin bath is wound around a rotating mold (mandrel), tensioned at a certain angle with respect to the rotation axis, and wound to the required thickness. It is.

  The fiber-reinforced composite material of the present invention is suitable for use in forming a reinforcing layer of a pressure vessel. In addition, the fiber-reinforced composite material of the present invention can also be used for applications such as power parts such as shafts and body parts such as engine hoods.

Next, the pressure vessel of the present invention will be described.
The pressure vessel of the present invention has an airtight liner and a reinforcing layer formed of a fiber reinforced composite material that reinforces the outside of the liner, and the fiber reinforced composite material is a fiber reinforced composite of the present invention. It can be the same as that of the conventional pressure vessel except being a material. Below, a preferable example of the pressure vessel of this invention is demonstrated below.

  As the liner, a metal made of aluminum or the like, or a made of resin except for a base portion for further weight reduction is used. As the resin, polyethylene, polyamide, polypropylene, ABS, polycarbonate or the like is used. Such a resin liner can be manufactured by a blow molding method, and an airtight inner shell can be formed by integrally joining the base portions during blow molding.

  The reinforcing layer is typically composed of a hoop layer and a helical layer depending on the arrangement of rovings (fiber bundles) to be wound. The hoop layer is arranged at about ± 75 ° to ± 105 ° with respect to the axial direction of the container, the helical layer is arranged at about ± 25 ° to ± 75 °, and the hoop layer and the helical layer are formed by a plurality of layers, respectively. The hoop layer and the helical layer thus formed are alternately repeated. The layer thickness is designed to withstand the stresses calculated according to the pressure applied to the pressure vessel. Since the fiber reinforced composite material of the present invention has excellent strength characteristics in the fiber direction, the strength is designed in the fiber direction of each of the hoop layer and the helical layer.

  Since the pressure vessel of the present invention is mostly made of a resin, it is lighter than a metal vessel and is used for a hydrogen storage vessel for a fuel cell vehicle and a natural gas storage vessel for a natural gas vehicle. And improvement in fuel consumption can be expected. In addition to automotive applications, it can also be used for medical gas storage containers.

  Hereinafter, the fiber-reinforced composite material and pressure vessel of the present invention will be described in more detail with reference to production examples and examples, but the present invention is not limited thereto.

The following production examples 1 and 2 and the following comparative production examples 1 and 2 are production examples of the (A) rubber-modified epoxy resin and comparative production examples thereof. The following production examples 3 and 4 and the following comparative production examples 3 to 5 are: It is a manufacture example of an epoxy resin composition, and its comparative manufacture example.
The following Examples 1 and 2 and Comparative Examples 1 and 2 are examples of the fiber-reinforced composite material of the present invention and comparative examples thereof.

[Production Example 1] (A) Production of rubber-modified epoxy resin EPR-1 225 parts by mass of bisphenol A type epoxy resin (epoxy equivalent = 185, manufactured by ADEKA Corporation, Adeka Resin EP-4300E) at 23 ° C., 23 ° C. 150 parts by weight of a liquid terminal carboxyl group-containing nitrile butadiene rubber (1) (carboxyl equivalent = 1753, nitrile content = 26%, manufactured by CVC Thermoset Specialities, CTBN (1300X13)) was heated to 100 ° C. At 100 ° C., 0.1 part by mass of triphenylphosphine was added and reacted at 130 to 150 ° C. for 4 hours. After confirming that the acid value is 1 mgKOH / g or less, 625 parts by mass of liquid bisphenol F type epoxy resin (epoxy equivalent = 170, manufactured by ADEKA Corporation, Adeka Resin EP-4901E, liquid at 23 ° C.), 90 Mix for 1 hour at ~ 100 ° C. The obtained mixture was named rubber-modified epoxy resin EPR-1.

[Production Example 2] (A) Production of rubber-modified epoxy resin EPR-2 225 parts by mass of bisphenol A type epoxy resin (epoxy equivalent = 185, manufactured by ADEKA Corporation, Adeka Resin EP-4300E) at 23 ° C., 23 ° C. 150 parts by weight of a liquid terminal carboxyl group-containing nitrile butadiene rubber (2) (carboxyl equivalent = 1935, nitrile content = 18%, manufactured by CVC Thermoset Specialities, CTBN (1300 × 8)) was heated to 100 ° C. At 100 ° C., 0.1 part by mass of triphenylphosphine was added and reacted at 130 to 150 ° C. for 4 hours. After confirming that the acid value is 1 mgKOH / g or less, 225 parts by mass of liquid bisphenol F type epoxy resin (epoxy equivalent = 170, manufactured by ADEKA Corporation, Adeka Resin EP-4901E, liquid at 23 ° C.) Carboxylic acid glycidyl ester (epoxy equivalent = 245, manufactured by HEXION Specially Chemicals, Cardura N10) was charged in 300 parts by mass and mixed at 90 to 100 ° C for 1 hour. The obtained mixture was named rubber-modified epoxy resin EPR-2.

[Comparative Production Example 1] Production of rubber-modified epoxy resin EPR-3 (comparative production example with respect to Production Example 1)
225 parts by mass of bisphenol A type epoxy resin (epoxy equivalent = 475, manufactured by ADEKA, Adeka Resin EP-5100) solid at 23 ° C., and terminal carboxyl group-containing nitrile butadiene rubber (1) (carboxyl equivalent = 23 ° C.) 1753, Nitrile content = 26%, CVC Thermoset Specialities, CTBN (1300 × 13)) was charged in 150 parts by mass and heated to 100 ° C. At 100 ° C., 0.1 part by mass of triphenylphosphine was added and reacted at 130 to 150 ° C. for 4 hours. After confirming that the acid value is 1 mgKOH / g or less, 625 parts by mass of liquid bisphenol F type epoxy resin (epoxy equivalent = 170, ADEKA Resin EP-4901E manufactured by ADEKA Corporation, liquid at 23 ° C.) is charged, Mix at 100 ° C. for 1 hour. The obtained mixture was named rubber-modified epoxy resin EPR-3.

[Comparative Production Example 2] Production of rubber combined epoxy resin EPR-4 (Comparative Production Example to Production Example 1)
225 parts by mass of liquid bisphenol A type epoxy resin (epoxy equivalent = 185, manufactured by ADEKA, Adeka Resin EP-4300E) at 23 ° C., powdered nitrile butadiene rubber (XER-91P, manufactured by JSR Corporation) at 23 ° C. 150 parts by mass, heated to 100 ° C., and mixed at 90-100 ° C. for 4 hours. Next, 625 parts by mass of liquid bisphenol F-type epoxy resin (epoxy equivalent = 170, manufactured by ADEKA, Adeka Resin EP-4901E, liquid at 23 ° C.) was mixed at 90 to 100 ° C. for 1 hour. The resulting mixture was designated as rubber combined epoxy resin EPR-4.

[Production Examples 3 to 4 and Comparative Production Examples 3 to 5]
An epoxy resin composition was produced with the formulation shown in [Table 1] below. About the obtained epoxy resin composition, the impregnation evaluation with respect to a reinforced fiber, an elongation test, and mixed viscosity measurement were performed by the following methods, respectively. The results are shown in [Table 1].

<Elongation test method>
In accordance with JIS K 6251, the elongation at break (%) and the maximum point stress (MPa) were measured. For both the elongation at break and the maximum point stress, the test piece was dumbbell No. 2 and the test speed was 5 mm / min. Moreover, the test piece was produced on the hardening conditions of heating at 100 degreeC for 4 hours, after heating at 80 degreeC for 2 hours.

<Mixed viscosity measurement method>
Measurement was performed at 25 ° C. using a B-type viscometer.

[Examples 1 and 2 and Comparative Examples 1 and 2]
Using the epoxy resin compositions of Production Examples 3 and 4 and Comparative Production Examples 3 and 4, and glass fibers as reinforcing fibers, fiber reinforced composite materials were produced. The manufacturing method of a fiber reinforced composite material is as follows. In addition, the usage-amount of the epoxy resin composition was 38% by volume content.
(Manufacturing method of fiber reinforced composite material)
The production of the fiber reinforced composite material was performed by a filament winding method. The fiber reinforced composite material was formed into a 3 mm plate shape for use in evaluations such as a tensile test. Since the filament winding method winds roving around a rotating mold, the rotating mold is preferably a cylindrical mold. However, in the present invention, as shown in FIG. The mold (mandrel) was used. Moreover, in order to make a fiber into one direction, it shape | molded in the hoop winding, without giving an angle as much as possible. The resin was impregnated in a roving bundled with fibers in a state maintained at a predetermined temperature by a resin bath arranged just before winding around the mold. After roving was wound to a predetermined thickness, it was heated at 80 ° C. for 2 hours, and further heated at 100 ° C. for 4 hours to be cured to obtain a fiber-reinforced composite material.

About the obtained fiber reinforced composite material, the tension test, the impregnation evaluation with respect to the fiber reinforced composite material, and the tensile fatigue test were each performed by the following methods. The results are shown in [Table 2].
<Tensile test method>
In accordance with JIS K 7165, tensile strength (MPa) and breaking strain (%) were measured. As for the shape of the test piece, in accordance with JIS K7165, an A-type test piece was used for the tensile test in the fiber direction, and a B-type test piece was used for the tensile test in the direction perpendicular to the fiber.
<Impregnation evaluation method for fiber reinforced composite material>
The molded plate was cut in a direction orthogonal to the reinforcing fibers, and the polished cut surface was observed with an optical microscope, and the distribution states of the fibers and the resin were compared. The photographs of the cut surfaces of the plate materials of Example 1 and Comparative Examples 1 and 2 with an optical microscope are shown in FIG. 2 and FIG. 3, respectively.
In Table 2, “good” means that the resin was uniformly dispersed in the gap between the fibers.
<Tensile fatigue test method>
Using the A-type test piece used in the tensile test, stress was repeatedly applied in the fiber direction at a stress of 600 MPa and a frequency of 1 Hz, and the number of times until breakage was measured.

Claims (5)

An epoxy resin composition containing (A) 100 parts by mass of a rubber-modified epoxy resin, (B) 50 to 150 parts by mass of an epoxy resin curing agent, and (C) 0.1 to 5 parts by mass of a curing accelerator is impregnated into the reinforcing fiber. Being
(A) The rubber-modified epoxy resin is (a) 100 parts by mass of a reaction product obtained by reacting an aromatic epoxy resin that is liquid at room temperature with (b) a terminal carboxyl group-containing nitrile butadiene rubber that is liquid at room temperature . It is a rubber-modified epoxy resin obtained by mixing 20 to 300 parts by mass of liquid bisphenol F-type epoxy resin and / or 30 to 150 parts by mass of tertiary carboxylic acid glycidyl ester,
(B) A fiber-reinforced composite material, wherein the epoxy resin curing agent is an acid anhydride type curing agent .   (A) The fiber-reinforced composite material according to claim 1, wherein the aromatic epoxy resin which is liquid at room temperature is a bisphenol A type epoxy resin. The fiber-reinforced composite material according to claim 1 or 2 , wherein a mixed viscosity of the epoxy resin composition is 2000 mPa · s or less at 25 ° C. The fiber-reinforced composite material according to any one of claims 1 to 3 , wherein a curing temperature of the epoxy resin composition is 100 ° C or lower. The pressure vessel having an airtight liner and a reinforcing layer formed of a fiber reinforced composite material that reinforces the outside of the liner, wherein the fiber reinforced composite material is according to any one of claims 1 to 4 . A pressure vessel which is a fiber reinforced composite material.