JP2019077763A - Epoxy resin composition, epoxy resin cured product, prepreg, and fiber-reinforced composite material - Google Patents

Abstract

To provide an epoxy resin composition which gives an epoxy resin cured product maintaining a high elastic modulus and having excellent toughness, and to provide a fiber-reinforced composite material excellent in compressive strength and interlayer toughness by using the epoxy resin composition.SOLUTION: The epoxy resin composition comprises at least the following constituent elements [A]-[D], and [B] and [C] are dissolved in [A]: [A] an epoxy resin; [B] a polysulfone-based resin having a weight average molecular weight of 2,000-20,000 g/mol; [C] a polysulfone-based resin having a weight average molecular weight of greater than 20,000 g/mol and 100,000 g/mol or less; and [D] an epoxy resin curing agent.SELECTED DRAWING: None

Description

  The present invention relates to a fiber-reinforced composite material suitable for aerospace applications, a prepreg for obtaining the same, and an epoxy resin composition suitably used as a matrix resin thereof.

  In recent years, fiber reinforced composite materials using reinforcing fibers such as carbon fibers and aramid fibers make use of their high specific strength and specific elastic modulus to construct structural materials for aircrafts and automobiles, tennis rackets, golf shafts, fishing rods, etc. It has been used for sports and general industrial applications.

  The method for producing the fiber-reinforced composite material uses a prepreg, which is a sheet-like intermediate material in which reinforcing fibers are impregnated with uncured matrix resin, and a plurality of sheets are laminated and heat-cured, or in a mold A liquid resin is poured into the arranged reinforcing fiber to obtain an intermediate, and a resin transfer molding method or the like in which the intermediate is heat-cured is used. Among these production methods, the method using a prepreg has an advantage that it is easy to obtain a high-performance fiber-reinforced composite material because the orientation of reinforcing fibers can be strictly controlled and the degree of freedom in design of the laminate configuration is high. A thermosetting resin is mainly used as the matrix resin used for this prepreg from the viewpoint of productivity such as heat resistance and processability, and among them, the adhesiveness and dimensional stability between the resin and the reinforcing fiber, and obtained An epoxy resin is preferably used from the viewpoint of mechanical properties such as strength and rigidity of the composite material.

  Among them, fiber reinforced composite materials for aerospace applications are required to have strength properties and durability stability, and high elasticity and heat resistance have been secured by using an amine type epoxy resin as a matrix resin. However, amine type epoxy resins tend to be highly crosslinked, and the cured product tends to be brittle. Then, the method of mix | blending the polysulfone type-resin which is excellent in heat resistance and toughness with respect to such resin is known. However, in this method, as the blending amount of the thermoplastic resin is increased, the elastic modulus of the cured product is decreased, and the viscosity of the resin is further increased, which may cause deterioration of the processability.

  Therefore, a method has been proposed in which the infiltration of the reinforcing fiber is improved by blending a large amount of low molecular weight polyether sulfone, and the in-plane shear strength of the fiber-reinforced composite material is developed (see Patent Document 1). . In addition, by arranging polysulfone resin particles not soluble in epoxy resin on the surface of the prepreg, adhesion with the substrate is enhanced, and a high elongation matrix resin is obtained by dissolving polysulfone resin in epoxy resin. There has also been proposed a technique for achieving a practical improvement in toughness (see Patent Document 2). Furthermore, Patent Document 3 discloses a method of blending a low molecular weight polyether sulfone having a weight average molecular weight of 21,000 to obtain excellent processability of a prepreg and to obtain high toughness of a fiber reinforced composite material. ing.

International Publication No. 2016/136052 JP, 2016-169381, A JP, 2016-147925, A

  When a low molecular weight polyethersulfone is blended in a large amount as in Patent Document 1, although a decrease in elastic modulus and heat resistance is suppressed, a certain toughness effect may not be obtained.

  Further, in the method of Patent Document 2, the polysulfone-based resin which is not dissolved in the epoxy resin may be unevenly present on the surface of the prepreg, and the toughness may not be sufficiently expressed.

  Moreover, although the low molecular-weight polyether sulfone is used for patent document 3, when a weight average molecular weight is 21,000, it is difficult on a process to mix | blend abundantly, and it was not able to fully express toughness.

  Therefore, an object of the present invention is to provide an epoxy resin composition which maintains a high elastic modulus and gives an epoxy resin cured product having excellent toughness. Furthermore, it is providing a fiber reinforced composite material excellent in compressive strength and interlayer toughness by using such an epoxy resin composition.

  The present invention has any of the following configurations in order to achieve the above object. That is, the present invention is configured as follows.

Epoxy resin composition [A] epoxy resin [B] weight average molecular weight 2,000 to 20 having at least components [A] to [D], and [B] and [C] dissolved in [A] Polysulfone-based resin [C] having a weight average molecular weight of 20,000 and 100,000 g / mol or less, which is 1,000 g / mol, polysulfone-based resin [D] epoxy resin curing agent A prepreg obtained by impregnating a resin composition with a reinforcing fiber can be used, and a fiber reinforced composite material including a cured product of the epoxy resin composition and a reinforcing fiber can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the epoxy resin composition which maintains an elasticity modulus and gives the epoxy resin cured material which has the outstanding toughness is obtained. Furthermore, by using such an epoxy resin composition, a fiber-reinforced composite material excellent in compressive strength and interlayer toughness can be obtained.

The epoxy resin composition of the present invention is characterized by having at least the following components [A] to [D], and [B] and [C] dissolved in [A].
[A] Epoxy resin [B] polysulfone resin having a weight average molecular weight of 2,000 to 20,000 g / mol, polysulfone based resin [C] having a weight average molecular weight of 20,000 and 100,000 g / mol or less [D] Epoxy resin curing agent Component [A] (sometimes referred to as component [A] as component [A]) in the present invention is an epoxy resin, and the basis of mechanical properties and handleability of the cured epoxy resin It is eggplant. The epoxy resin in the present invention means a compound having one or more epoxy groups in one molecule.

  Specific examples of the epoxy resin in the present invention include an aromatic glycidyl ether obtained from a phenol having a plurality of hydroxyl groups, an aliphatic glycidyl ether obtained from an alcohol having a plurality of hydroxyl groups, a glycidyl amine obtained from an amine, and a carboxylic acid having a plurality of carboxyl groups. The glycidyl ester obtained from an acid, the epoxy resin which has an oxirane ring, etc. are mentioned.

  Among them, glycidyl amine type epoxy resins can be suitably used because they are low in viscosity and excellent in impregnating properties to reinforcing fibers and excellent in heat resistance and mechanical properties such as elastic modulus when made into fiber reinforced composite materials. Such glycidyl amine type epoxy resins can be roughly classified into polyfunctional amine type epoxy resins and bifunctional amine type epoxy resins.

  The multifunctional amine epoxy resin refers to a glycidyl amine epoxy resin containing three or more epoxy groups in one epoxy resin molecule. For example, tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, tetraglycidyl xylylenediamine, halogen-substituted products thereof, alkyl-substituted products, alkyl-substituted products, aralkyl-substituted products, allyl-substituted products, alkoxy-substituted products, aralkoxy-substituted products, allyloxy-substituted products, water An accessory etc. can be used.

  The polyfunctional amine type epoxy resin is not particularly limited, but tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, tetraglycidyl xylylene diamine and substituted products thereof, hydrogenated products thereof and the like are suitably used.

  As said tetraglycidyl diamino diphenyl methane, "Sumi epoxy (registered trademark)" ELM 434 (Sumitomo Chemical Industry Co., Ltd. product), YH 434L (Nippon Steel Sumikin Chemical Co., Ltd. product), "jER (registered trademark)" 604 (Mitsubishi Chemical Co., Ltd. ), "Araldite (registered trademark)" MY720, "Araldite (registered trademark)" MY 721 (manufactured by Huntsman Advanced Materials, Inc.) and the like can be used. As triglycidyl aminophenol and its alkyl-substituted product, “Sumiepoxy (registered trademark)” ELM 100, “Sumiepoxy (registered trademark)” ELM 120 (all manufactured by Sumitomo Chemical Co., Ltd.), “araldite (registered trademark)” MY0500, Use “Araldite®” MY0510, “Araldite®” MY0600 (above, made by Huntsman Advanced Materials, Inc.), “jER®” 630 (made by Mitsubishi Chemical Corporation), etc. be able to. As tetraglycidyl xylylene diamine and a hydrogenated product thereof, “TETRAD (registered trademark)”-X, “TETRAD (registered trademark)”-C (all manufactured by Mitsubishi Gas Chemical Co., Ltd.) and the like can be used.

  The polyfunctional amine type epoxy resin is preferably used as the epoxy resin in the present invention because it is excellent in the heat resistance of the obtained cured epoxy resin product and the balance with mechanical properties such as elastic modulus. According to a further preferred embodiment, 30 to 80 parts by mass of the polyfunctional amine epoxy resin is desirably contained with respect to 100 parts by mass of the total epoxy resin in the epoxy resin composition.

  The bifunctional amine type epoxy resin refers to a glycidyl amine type epoxy resin containing two epoxy groups in one molecule. For example, diglycidyl aniline, a halogen-substituted product thereof, an alkyl-substituted product, an aralkyl-substituted product, an allyl-substituted product, an allyl-substituted product, an alkoxy-substituted product, an aralkoxy-substituted product, an allyloxy-substituted product, a hydrogenated product or the like can be used.

  The bifunctional amine type epoxy resin is not particularly limited, and examples thereof include diglycidyl aniline, diglycidyl toluidine, halogens thereof, alkyl-substituted products, hydrogenated products and the like.

  As said diglycidyl aniline, GAN (made by Nippon Kayaku Co., Ltd.), PxGAN (made by Toray Fine Chemical Co., Ltd.) etc. can be used. As diglycidyl toluidine, GOT (Nippon Kayaku Co., Ltd. product) etc. can be used.

  The bifunctional amine type epoxy resin is preferably used as the epoxy resin in the present invention because the fiber reinforced composite material is excellent in strength development, has a low viscosity, and the impregnation property to the reinforcing fiber is improved. According to a further preferred embodiment, the bifunctional amine type epoxy resin is desirably contained in an amount of 10 to 60 parts by mass with respect to 100 parts by mass of the total epoxy resin in the epoxy resin composition. Also, in view of the balance between adhesion to reinforcing fibers and mechanical properties, a combination with a polyfunctional amine type epoxy resin is preferable, and 40 to 70 parts by mass of a multifunctional amine type epoxy resin in all epoxy resin compositions, bifunctional amine More preferably, 20 to 50 parts by mass of the epoxy resin is contained.

  Moreover, in the range which does not impair the effect of this invention, you may contain the other epoxy resin component other than an amine type epoxy resin as epoxy resin [A]. Specifically, bisphenol A type, bisphenol F type, bisphenol S type, bisphenol AD type, halogen of these bisphenols, alkyl-substituted product, hydrogenated product and the like are used as the bisphenol type epoxy resin. The following are mentioned as a specific example of this epoxy resin.

  As a commercial item of bisphenol A type epoxy resin, "Epotote (registered trademark)" YD128 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), "jER (registered trademark)" 825, "jER (registered trademark)" 828, " jER (registered trademark) 834, jER (registered trademark) 1001, jER (registered trademark) 1004, jER (registered trademark) 1007, jER (registered trademark) 1009, jER (registered trademark) “1010 (above, manufactured by Mitsubishi Chemical Co., Ltd.) and the like.

  Commercial products of bisphenol F type epoxy resin include “Epiclon (registered trademark)” 830, “Epiclon (registered trademark)” 835 (all manufactured by DIC Corporation), “jER (registered trademark)” 806, “jER (registered trademark)”. “Registered Trademark” “807”, “jER (registered trademark)” 4004 P, “jER (registered trademark)” 4007 P, “jER (registered trademark)” 4009 P, “jER (registered trademark)” 4010 P (all manufactured by Mitsubishi Chemical Corporation) And “Epototh (registered trademark)” YDF-170, and “Epototh (registered trademark)” YDF-2001 (all manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.).

  As a bisphenol S-type epoxy resin, "Epiclon (registered trademark)" EXA-1514 (made by DIC Corporation) etc. are mentioned.

  Examples of commercially available products of bisphenol AD type epoxy resin include "EPOMIK (registered trademark)" R710, and "EPOMIK (registered trademark)" R1710 (manufactured by PRINTEC CO., LTD.).

  Component [B] (sometimes referred to as component [B]) and component [C] (sometimes referred to as component [C]) in the present invention are polysulfone-based resins that are soluble in epoxy resin [A]. The term "dissolving" as used herein refers to heating and kneading the epoxy resin [A] at 100 to 180 ° C. for 30 to 120 minutes and not existing in the form of particles in the epoxy resin. It is a state where it can be confirmed that it does not exist in the form of particles by an optical method such as an optical microscope that the resin does not exist in the form of indeterminate form, spherical form, plate form or the like in the epoxy resin. By dissolving the component (B) and the component (C) in the epoxy resin (A), the polysulfone resin can be uniformly present in the epoxy resin, which leads to the development of toughness.

  The polysulfone-based resin in the present invention refers to a thermoplastic resin having a sulfone bond in the main chain. Such polysulfone-based resin may have a partially crosslinked structure. Specific examples thereof include polysulfone, polyethersulfone and polyetherethersulfone. Among them, polyethersulfone having high heat resistance and high compatibility with epoxy resin can be suitably used.

  Examples of commercially available products of the component [B] include polysulfones such as “Virantage (registered trademark)” VW-30500RP (manufactured by Solvay Advanced Polymers).

  The component [B] can be produced, for example, by the methods described in JP-B-42-7799, JP-B-45-21318, and JP-A-48-19700. According to the document, in the presence of an alkali metal compound such as sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate, 4,4 in an aprotic polar solvent such as N-methylpyrrolidone, DMF, DMSO or sulfolane It can be obtained by polycondensation of a dihydric phenol compound such as' -dihydroxydiphenyl sulfone and a dihydric dihalogeno diphenyl compound such as 4,4'-dichlorodiphenyl sulfone. However, in the method, if conditions are carefully selected, polyether sulfone which is a preferable embodiment of the target [B] component is obtained, but depending on polymerization conditions, the terminal hydroxyphenyl group of the obtained polyether sulfone The ratio is low, and when it is attempted to further increase the ratio of terminal hydroxyphenyl groups, the polymer molecular weight decreases significantly, and it is difficult to recover polyether sulfone, which is a preferred embodiment of the target [B] component from the reaction solution May be Therefore, as a preferred method for producing polyether sulfone, which is a preferred embodiment of the component [B] used in the present invention, first, a generally known method, that is, a high molecular weight obtained by polycondensation of a dihydric phenol compound and a dihalogeno diphenyl compound The method of introducing the hydroxyphenyl group at the terminal and producing by using the polyether sulfone of the following as a raw material and subsequently heating the high molecular weight polyether sulfone and the dihydric phenol compound obtained in an aprotic polar solvent .

Moreover, as for the terminal of the polyether sulfone which is a preferable aspect of a [B] component, it is preferable that 60 mol% or more of the terminal is a hydroxyphenyl group. By reacting this functional group with the epoxy resin or the curing agent of the epoxy resin, the affinity with the phase consisting of the epoxy resin becomes high, and it is uniformly compatible, and a high elastic modulus can be secured when the epoxy resin composition is formed. From this point of view, the ratio of the hydroxyphenyl group at the end of the polyethersulfone, which is a preferred embodiment of the component [B], is preferably as high as possible, and most preferably all the ends are hydroxyphenyl groups. Depending on the type of epoxy resin and the curing temperature of the matrix resin, the hydroxyphenyl group is less than 60 mol% of the end (meaning that the proportion of the hydroxyphenyl group at the end of the polyethersulfone is less than 60 mol%. And the compatibility may not be sufficient and the elastic modulus may not be sufficient. The ratio of the terminal being a hydroxyphenyl group is, for example, to a chlorine atom substituted with chlorinated aromatic carbon at 7.7 ppm by using 400 MHz ¹ H-NMR in deuterated DMSO solvent, using 100 MHz of integration times. Adjacent proton ( ¹ HCl) and proton ( ¹ HOH) adjacent to aromatic carbon substituted with hydroxyl group at 6.9 ppm can be observed with high resolution, ¹ H-NMR area ratio reflects the number of moles From the above, the terminal functional group composition (mol%) can be calculated by the following formula.

[Terminal hydroxyl group composition (mol%)] = [peak area of ¹ HOH] / ([peak area of ¹ HOH] + [peak area of ¹ HCl]) × 100.

  As a commercially available product of polyether sulfone which is a preferable embodiment of the [C] component in the present invention, "Sumica Excel (registered trademark)" PES 3600 P, "Sumica Excel (registered trademark)" PES 5003 P, "Sumica Excel (registered trademark)" PES 5200 P, "Sumika Excel (registered trademark)" PES 7600P (above, Sumitomo Chemical Co., Ltd.), "Ultrason (registered trademark)" E2020P SR, "Ultrason (registered trademark)" E6020P (above, BASF Corporation), " Virantage (registered trademark) “VW-10700RP (manufactured by Solvay Advanced Polymers), etc. can be used, and polyether sulfone and polyether ether sulfone as described in JP-A-2004-506789 are also usable. Copolymer oligomers etc. are mentioned. Moreover, "UDEL (trademark)" P-3500 (made by Solvay Advanced Polymers KK) which is a commercial item of polysulfone, etc. are mentioned.

  The weight average molecular weight of the component [B] is in the range of 2,000 to 20,000 g / mol, preferably in the range of 4,000 to 15,000 g / mol, and more preferably 4,000 to 10, It is in the range of 000 g / mol. Furthermore, the weight average molecular weight of the component [C] is more than 20,000 and in the range of 100,000 g / mol or less, preferably in the range of 30,000 to 80,000 g / mol. When the component (B) and the component (C) are in this range, the component (B) and the component (C) can be present in the epoxy resin without causing deterioration in processability due to an increase in resin viscosity, The toughness of the cured epoxy resin can be developed. Here, the weight average molecular weights of the [B] component and the [C] component indicate relative molecular weights obtained by GPC (Gel Permeation Chromatography) using polystyrene standard samples.

  The present inventors set conditions of weight average molecular weight in the range of [B] and [C], specifically, the [B] component has a weight average molecular weight of 2,000 to 20,000 g / mol, and the [C] component has By satisfying the weight average molecular weight of 20,000 or more and 100,000 g / mol or less, a technology has been found that can be molded without problems even in the compounding amount region of thermoplastic resin, which is conventionally difficult to mold due to the resin viscosity. As a result, it has been possible to lead to an outstanding increase in toughness while maintaining the elastic modulus of the cured epoxy resin.

  In the present invention, the component [B] is preferably contained in an amount of 25 to 50% by mass, more preferably 30 to 45% by mass, based on 100% by mass of the epoxy resin composition. If it is less than 25% by mass, the modulus of elasticity of the cured epoxy resin may decrease. If the content is more than 50% by mass, the viscosity of the epoxy resin composition may increase, and the processability and the handleability of the epoxy resin composition and the prepreg may be insufficient.

  In the present invention, the component [C] is preferably contained in an amount of 2 to 10% by mass, more preferably 4 to 8% by mass, based on 100% by mass of the epoxy resin composition. If it is less than 2% by mass, it may be difficult to develop toughness of the cured epoxy resin product. When the content is more than 10% by mass, the viscosity of the epoxy resin composition may increase, and the processability and handleability of the epoxy resin composition and the prepreg may be insufficient. In addition, the elastic modulus and the heat resistance of the cured epoxy resin may be lowered.

  Moreover, it is preferable that the glass transition temperature of the [B] component in this invention and a [C] component is 180 degreeC or more and 230 degrees C or less. If it is less than 180 ° C., the heat resistance may be lowered depending on the heat resistance of the epoxy resin, and if it exceeds 230 ° C., the glass transition temperature of the matrix resin becomes high. Thermal stress may increase, and the mechanical properties of the fiber-reinforced composite material may deteriorate.

  The epoxy resin composition of the present invention contains an epoxy resin curing agent [D]. The epoxy resin curing agent (hereinafter, the epoxy resin curing agent may be abbreviated as a curing agent) is not particularly limited as long as it is a compound having an active group capable of reacting with an epoxy group, for example, dicyandiamide, Aromatic polyamines, aminobenzoic acid esters, various acid anhydrides, phenol novolak resins, cresol novolak resins, polyphenol compounds, imidazole derivatives, aliphatic amines, tetramethylguanidine, thiourea addition amines, methylhexahydrophthalic anhydride And carboxylic acid anhydrides, carboxylic acid hydrazides, carboxylic acid amides, polymercaptans and Lewis acid complexes such as boron trifluoride ethylamine complex and the like.

  Above all, by using an aromatic polyamine as a curing agent, an epoxy resin cured product having good heat resistance can be obtained. In particular, diaminodiphenyl sulfone or a derivative thereof, or various isomers thereof is a curing agent most suitable for obtaining a cured epoxy resin having good heat resistance.

  In addition, by combining dicyandiamide with a urea compound such as 3,4-dichlorophenyl-1,1-dimethylurea or using an imidazole as a curing agent, high heat and water resistance can be obtained while curing at a relatively low temperature. . Curing an epoxy resin using an acid anhydride gives a cured product having a low water absorption as compared to curing of an amine compound. In addition, the storage stability of the prepreg, in particular, the tackiness and the drapability hardly change even when it is left at room temperature, by using a latentening agent of these curing agents, for example, a microencapsulated one.

  The optimum value of the addition amount of the curing agent varies depending on the type of epoxy resin and the curing agent. For example, in the case of using an aromatic amine curing agent, the compounding amount thereof may be 0.6 to 1.2 times the amount of epoxy groups in the epoxy resin from the viewpoint of heat resistance and mechanical properties. Preferably, it is more preferably 0.7 to 1.1 times. If the ratio is less than 0.6 times, the crosslink density of the cured product may not be sufficient, so the modulus of elasticity and heat resistance may be insufficient, or the static strength properties of the fiber-reinforced composite material may be insufficient. If it exceeds 1.2 times, the crosslink density and the water absorption of the cured product may be too high, the deformability may be insufficient, and the impact resistance of the fiber composite material may be poor.

      Commercially available aromatic polyamine curing agents include Seikacure S (Wakayama Seika Kogyo Co., Ltd.), MDA-220, 3,3'-DAS (Mitsui Chemical Co., Ltd.), "jER Cure (registered). Trademark "W" (Mitsubishi Chemical Co., Ltd. product), "Lonzacure (R)" M-DEA, "Lonzacure (R)" M-DIPA, "Lonzacure (R)" M-MIPA, "Lonzacure (R) "DETDA 80" (manufactured by Lonza Co., Ltd.) and the like.

  In the epoxy resin composition of the present invention, components (components) other than the epoxy resin curing agent [D] are first uniformly heated and kneaded at a temperature of about 160 ° C., and then cooled to a temperature of about 80 ° C. Although it is preferable to add and knead | mix an epoxy resin hardening | curing agent [D], the compounding method of each component is not specifically limited to this method.

When the epoxy resin composition of the present invention is used in a prepreg application, the viscosity at 80 ° C. is preferably 500 to 1900 Pa · s, more preferably 800 Pa · s to 1700 Pa., From the viewpoint of processability such as tack and drape. It is the range of s. If the viscosity at 80 ° C. is less than 500 Pa · s, the shape retention of the prepreg may be low, cracking may occur, and a large resin flow during molding may occur to cause variation in fiber content. There is a case. When the viscosity at 80 ° C. exceeds 1900 Pa · s, the resin composition may be faded in the film formation step, or an unimpregnated part may be generated in the impregnation step into the reinforcing fiber. The viscosity referred to here is a complex viscoelastic modulus η ^* measured at a temperature rising rate of 1.5 ° C./min, a frequency of 1 Hz, and a gap of 1 mm using a dynamic viscoelasticity measuring apparatus (ARES: made by TA Instruments Co., Ltd.) Point to that.

  The glass transition temperature of the epoxy resin cured product of the present invention is preferably 120 to 250 ° C., more preferably 140 to 210 ° C., from the viewpoint of sufficiently securing the heat resistance and the wet heat compression strength required for aircraft materials. is there. A relatively high curing temperature is required to cure and mold such an epoxy resin composition having relatively high heat resistance and a prepreg using the same. The prepreg currently used for the airframe structural material of an aircraft generally has a curing molding temperature in the range of 180 ± 10 ° C. In addition, in order to sufficiently develop the strength of the fiber-reinforced composite material formed by curing and forming, it is general to perform the curing and forming of the prepreg laminate under a pressure condition of 1 atmosphere or more.

  The epoxy resin composition of the present invention is a coupling agent, a thermosetting resin particle, or a thermoplastic resin other than the component [B] and the component [C], within the range not impairing the effects of the present invention, thermoplastic resin particles Inorganic fillers such as elastomer, silica gel, carbon black, clay, carbon nanotube, metal powder, etc. can be blended.

  The reinforcing fibers used in the present invention include glass fibers, carbon fibers, graphite fibers, aramid fibers, boron fibers, alumina fibers, silicon carbide fibers and the like. Two or more types of these reinforcing fibers may be mixed and used, but it is preferable to use carbon fibers and graphite fibers in order to obtain a molded article having a lighter weight and higher durability. In particular, in applications where the demand for weight reduction and high strength of materials is high, carbon fibers are suitably used because of their excellent specific modulus and specific strength.

  The carbon fiber preferably used in the present invention may be any kind of carbon fiber depending on the application, but is preferably a carbon fiber having a tensile modulus of 400 GPa or less from the viewpoint of impact resistance. Further, from the viewpoint of strength, a carbon fiber having a tensile strength of preferably 4.4 to 6.5 GPa is used because a composite material having high rigidity and mechanical strength can be obtained. Moreover, tensile elongation is also an important factor, and it is preferable that it is high strength high elongation carbon fiber of 1.7 to 2.3%. Therefore, carbon fibers having the properties of a tensile modulus of at least 230 GPa, a tensile strength of at least 4.4 GPa and a tensile elongation of at least 1.7% are most suitable.

  Commercially available carbon fibers include "TORAYCA.RTM." T800 G-24K, "TORAYCA.RTM." T800 S-24 K, "TORAYCA.RTM." T700 G-24 K, "TORAYCA.RTM." T300- 3K, and "TORAYCA.RTM." T700S-12K (manufactured by Toray Industries, Inc.) and the like.

  The form and arrangement of carbon fibers can be appropriately selected from long fibers and fabrics aligned in one direction, but in order to obtain a carbon fiber-reinforced composite material that is lightweight and has a higher durability, carbon fibers It is preferable that it is in the form of continuous fibers such as long fibers (fiber bundles) aligned in one direction or a woven fabric.

  The prepreg of the present invention is obtained by impregnating the above-mentioned epoxy resin composition into the above-mentioned reinforcing fiber. The fiber mass fraction of the prepreg is preferably 40 to 90% by mass, more preferably 50 to 80% by mass. If the fiber mass fraction is too low, the mass of the resulting composite material may be excessive, and the advantages of the fiber-reinforced composite material excellent in specific strength and specific modulus may be lost, and if the fiber mass fraction is too high. Poor impregnation of the resin composition occurs, the resulting composite material tends to have many voids, and its mechanical properties may be greatly reduced.

  The form of the reinforcing fiber is not particularly limited, and for example, long fibers aligned in one direction, a tow, a woven fabric, a mat, a knit, a braid, etc. are used. Also, for applications where high specific strength and high specific modulus are required in particular, a unidirectional arrangement of reinforcing fibers is most suitable, but it is in the form of a cloth that is easy to handle. Sequences are also suitable for the present invention.

  In the prepreg of the present invention, the epoxy resin composition used as a matrix resin is dissolved in a solvent such as methyl ethyl ketone or methanol to lower the viscosity, and impregnated into reinforcing fibers (wet method); It can be prepared by a hot-melt method (dry method) or the like in which a viscosity is increased and impregnated into reinforcing fibers.

  The wet method is a method in which a reinforcing fiber is immersed in a solution of an epoxy resin composition which is a matrix resin, and then pulled up, and the solvent is evaporated using an oven etc. The hot melt method (dry method) is a method of low viscosity by heating. A method of impregnating a reinforced epoxy resin composition directly into a reinforcing fiber, or preparing a film in which the epoxy resin composition is once coated on a release paper or the like, and then laminating the film from both sides or one side of the reinforcing fiber This is a method of impregnating a reinforcing fiber with a resin by heating and pressing. According to the hot melt method, substantially no solvent remains in the prepreg, which is a preferred embodiment in the present invention.

  After laminating the obtained prepreg, the fiber-reinforced composite material according to the present invention is produced by a method of heating and curing the matrix resin while applying pressure to the laminate.

  Here, as a method of applying heat and pressure, a press forming method, an autoclave forming method, a bag forming method, a wrapping tape method, an internal pressure forming method and the like are adopted.

  The fiber-reinforced composite material of the present invention is a method in which an epoxy resin composition is directly impregnated into a reinforcing fiber without using a prepreg, and then heat curing is carried out, such as a hand layup method, a filament winding method, a pultrusion method, It can also be produced by molding methods such as resin injection molding method and resin transfer molding method. In these methods, it is preferable to prepare an epoxy resin composition by mixing two components of a main agent consisting of an epoxy resin and a curing agent immediately before use.

  The fiber reinforced composite material using the epoxy resin composition of the present invention as a matrix resin is suitably used in sports applications, aircraft applications and general industrial applications. More specifically, in aerospace applications, aircraft primary structural applications such as wings, tail and floor beams, secondary structural applications such as flaps, ailerons, cowls, fairings and interiors, rocket motor cases and satellites It is suitably used for structural material applications and the like. Among such aerospace applications, particularly in aircraft primary structural applications, in particular fuselage skins and wing skins, where low impact strength is required and tensile strength at low temperatures is required because they are exposed to low temperatures during advanced flight. The fiber-reinforced composite material according to the present invention is particularly preferably used. In sports applications, golf balls, fishing rods, tennis, rackets such as badminton and squash, stick applications such as hockey, and ski poles are suitably used. Furthermore, in general industrial applications, structural materials of moving bodies such as automobiles, ships and railway vehicles, drive shafts, leaf springs, wind turbine blades, pressure vessels, flywheels, paper rollers, roofing materials, cables, reinforcement bars, and repair reinforcements It is suitably used in civil engineering / building material applications such as materials.

  Hereinafter, the epoxy resin composition of the present invention will be more specifically described by way of examples. The preparation method and evaluation method of the resin raw material used in the Example are shown next.

<[A] Epoxy resin>
-"Sumiepoxy (registered trademark)" ELM 434 (tetraglycidyl diaminodiphenylmethane, manufactured by Sumitomo Chemical Co., Ltd.)
・ "JER (registered trademark)" 630 (triglycidyl aminophenol, manufactured by Mitsubishi Chemical Corporation)
-GAN (diglycidyl aniline, manufactured by Nippon Kayaku Co., Ltd.)
"Epiclon (registered trademark)" 830 (bisphenol F type epoxy resin, manufactured by DIC Corporation).

<[B] polysulfone-based resin having a weight average molecular weight of 2,000 to 20,000 g / mol>
・ Polyether sulfone synthesized by the following method (B-1, B-2, B-3)
(Method for producing B-1, B-2 and B-3: Reference is made to JP-A-5-86186. A specific production method is shown in Reference Example 1).
Reference Example 1
In a 1 L flask equipped with a stirrer, thermometer, condenser, distillate separator and nitrogen inlet tube, 4,4'-dihydroxydiphenyl sulfone (abbreviated as DHDPS hereinafter) (50.06 g, 0.20 mol) ), Toluene 100 ml, 1,3-dimethyl-2-imidazolidinone (250.8 g) and 40% aqueous potassium hydroxide solution (56.0 g, 0.39 mol) are weighed, and nitrogen gas is passed through the reaction while stirring The system was all purged with nitrogen. It was heated to 130 ° C. while passing nitrogen gas. As the temperature of the reaction system rose, reflux of toluene was started, water in the reaction system was removed by azeotropic distillation with toluene, and azeotropic dehydration was carried out at 130 ° C. for 4 hours while returning toluene to the reaction system. After this, 4,4'-dichlorodiphenyl sulfone (hereinafter abbreviated as DCDPS) (57.40 g, 0.20 mol) was added to the reaction system together with 40 g of toluene, and the reaction system was heated to 150 ° C. The reaction was carried out for 4 hours while distilling toluene, to obtain a highly viscous brown solution. The temperature of the reaction solution was cooled to room temperature, and the reaction solution was poured into 1 kg of methanol to precipitate polymer powder. The polymer powder was recovered by filtration, 1 kg of water was added thereto, 1N hydrochloric acid was further added, and the slurry solution was added to pH 3 to 4 to be acidified. After recovering the polymer powder by filtration, the polymer powder was washed twice with 1 kg of water. The mixture was further washed with 1 kg of methanol and vacuum dried at 150 ° C. for 12 hours. The obtained polymer powder is a white powder, and the yield is 88.3 g (yield 99.9%: yield = (92.8 / 464.53 (molecular weight of intermediate product of polyether sulfone component synthesis) / 0. Calculated from 2 × 100).

  Next, an intermediate product (5 g, 10.7 mmol (5 / 464.53 × 1000) of polyether sulfone component synthesis synthesized above in a 300 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, a thermometer, and a cooling tube Calculation) DHDPS (1.25 g, 4.35 mmol), 200 ml of N-methyl-2-pyrrolidone (NMP), and anhydrous potassium carbonate (0.6 g, 4.34 mmol) are weighed out), and the NMP reaction solution is stirred. While raising the reaction temperature to 150 ° C., the reaction is completed in 1 hour, the reaction solution is poured into 500 ml of methanol, the precipitated solid is crushed, washed twice with 500 ml of water, and vacuumed at 130 ° C. It was dry. The obtained polymer powder is white powdery, and the yield is 7.2 g, the yield is 96% (the yield is the mass of polyether sulfone which is the recovered polyether sulfone component / (intermediate product of polyether sulfone component synthesis charged Calculated by: amount + preparation DHDPS) × 100).

  Except that the weight average molecular weight of the polyethersulfone disclosed in JP-A-5-86186 is larger than that of [B], [B] is essentially the same as polyethersulfone described in JP-A-5-86186. Since it does not differ, according to the procedure of the above reference example, polyether sulfone B-1 to B-B having different weight average molecular weights and conversion rates of end groups by changing the amount of DHDPS, the amount of alkali metal, and the reaction time. -3 was synthesized and used in the examples. In addition, the weight average molecular weight was measured using WATERS company differential refractometer R-401 for a detector, and using WATERS company 201 D type gel permeation chromatograph GPC-5. As measurement conditions, o-chlorophenol / chloroform (volume ratio 2/8) was used as an eluent, and 0.1 ml of a solution having a sample temperature of 1 to 2 mg / ml was injected at a column temperature of 23 ° C. As a column, two Shodex 80M manufactured by Showa Denko KK and one Shodex 802 manufactured by Showa Denko K. K. were connected in series to make an eluent 1.0 ml / min. Polymer molecular weight was converted relative to a calibration curve with standard poly (methyl methacrylate).

Glass transition temperature Tg takes out 10 mg of [B] synthesized above, and measures it at a temperature range of 30 ° C. to 350 ° C. at a heating rate of 10 ° C./min using DSC 2910 manufactured by TA Instruments (model number). The heat resistance was evaluated by setting the midpoint temperature determined based on JIS K 7 12 1-1987 as the glass transition temperature Tg.
B-1 (polyether sulfone, weight average molecular weight: 4,000, hydroxyphenyl end group 100 mol%, Tg: 204 ° C.)
B-2 (polyether sulfone, weight average molecular weight: 7,000, hydroxyphenyl end group 100 mol%, Tg: 206 ° C.)
B-3 (polyether sulfone, weight average molecular weight: 18,000, hydroxyphenyl end group 86 mol%, Tg: 214 ° C.).
“Virantage®” VW-30500 RP (polysulfone, manufactured by Solvay Advanced Polymers, weight average molecular weight: 14,000).

<[C] polysulfone-based resin having a weight average molecular weight of more than 20,000 and 100,000 g / mol or less>
"Virantage (registered trademark)" VW-10700RP (polyether sulfone, Solvay Advanced Polymers Co., Ltd., weight average molecular weight: 21,000)
-"Sumika Excel (registered trademark)" PES 5003 P (polyether sulfone, manufactured by Sumitomo Chemical Co., Ltd., weight average molecular weight: 47,000).
"UDEL (registered trademark)" P-3500 (polysulfone, manufactured by Solvay Advanced Polymers, Ltd., weight average molecular weight: 80,000).

<Other ingredients>
Particles 1 (thermoplastic resin particles produced using "Grilamide (registered trademark)" TR 55 as a raw material)
(Method of producing particle 1: Reference to WO 2009/142231)
In a 100 ml four-necked flask, 2.5 g of amorphous polyamide (weight-average molecular weight 18,000, “Grillamide (registered trademark)” TR 55 manufactured by MESBER QUEUE) as polymer A, N-methyl-2-pyrrolidone as an organic solvent 42 .5 g and 5 g of polyvinyl alcohol as polymer B (Nippon Synthetic Chemical Industry Co., Ltd. "GoSenor (registered trademark)" GL-05) were added, and the mixture was heated to 80 ° C and stirred until the polymer was dissolved. After the temperature of the system was returned to room temperature, 50 g of ion-exchanged water as a poor solvent was dropped at a speed of 0.41 g / min via a feed pump while stirring at 450 rpm. The system turned white when 12 g of deionized water was added. After complete addition of water, the mixture was stirred for 30 minutes, and the obtained suspension was filtered, washed with 100 g of ion exchanged water, and vacuum dried at 80 ° C. for 10 hours to obtain 2.2 g of a white solid . When the obtained powder was observed with a scanning electron microscope, it was polyamide fine particles having an average particle diameter of 16.1 μm.

<Epoxy resin curing agent [D]>
-3,3'-DAS (3,3'- diamino diphenyl sulfone, Mitsui Chemicals Fine Co., Ltd. product).

(1) Preparation of Epoxy Resin Composition (Examples 1 to 11, Comparative Examples 1 to 2)
A predetermined amount of epoxy resin [A], polysulfone resin [B] and [C] is added to a kneader, and while kneading, the temperature is raised to 160 ° C. and kneading is carried out for 1 hour at 160 ° C. I got a liquid. After lowering the temperature to 80 ° C. while kneading, a predetermined amount of an epoxy resin curing agent [D] was added, and the mixture was further kneaded to obtain an epoxy resin composition.

(Comparative example 3)
The preparation method of the epoxy resin composition of patent document 2 (Unexamined-Japanese-Patent No. 2016-169381) was used. The lump or coarse particles of the polysulfone resin [C] were mechanically ground under liquid nitrogen using a hammer mill, and particles of 100 μm or more were cut using a vibrating sieve to obtain particles. The epoxy resin [A] and the polysulfone-based resin [B] were put into a metal beaker, and the mixture was heated and kneaded at 100 ° C. for 2 hours to completely dissolve the polysulfone-based resin [B]. Thereafter, an epoxy resin curing agent [D] was added and stirred to disperse uniformly. While kneading was continued, particulate polysulfone resin [C] was added, and the mixture was stirred and dispersed so as not to dissolve, to obtain an epoxy resin composition.

(2) Viscosity of epoxy resin composition (η ^* )
The viscosity of the epoxy resin composition is measured using a dynamic viscoelasticity measuring apparatus ARES (manufactured by TA Instruments), using a parallel plate with a diameter of 40 mm, and raising the temperature simply at a heating rate of 1.5 ° C./min. The value at 80 ° C. of the complex viscosity η ^* obtained under the measurement conditions of Gap 1 mm was adopted.

(3) Flexural modulus of epoxy resin cured product After degassing the epoxy resin composition prepared in the above (1) in vacuum, a 2 mm thick spacer made of "Teflon (registered trademark)" to have a thickness of 2 mm It injected | poured in the set mold. It was cured at a temperature of 180 ° C. for 2 hours to obtain an epoxy resin cured product having a thickness of 2 mm. Next, a test piece having a width of 10 mm and a length of 60 mm was cut out of the obtained epoxy resin cured product plate, and a three-point bend of 32 mm between spans was measured to determine a flexural modulus according to JIS K7171-1994.

(4) Measurement of Toughness (K _IC ) of Cured Epoxy Resin After degassing the epoxy resin composition prepared in the above (1) in vacuum, a 6 mm thick “Teflon (registered trademark)” spacer is used to make the thickness 6 mm In a mold set to be as described above, curing was carried out at a temperature of 180 ° C. for 2 hours to obtain an epoxy resin cured product having a thickness of 6 mm. The epoxy resin cured product was cut into a size of 12.7 × 150 mm to obtain a test piece. Test pieces were processed and tested according to ASTM D5045 (1999) using an Instron universal tester (manufactured by Instron). The introduction of the initial pre-crack into the test piece was performed by applying a razor blade cooled to liquid nitrogen temperature to the test piece and impacting the razor with a hammer. Here, the toughness of the cured epoxy resin refers to the critical stress intensity factor of the aperture mode I.

(5) Preparation of Prepreg The epoxy resin composition was applied onto release paper using a knife coater to prepare a resin film. Next, two resin films are stacked on both sides of the carbon fiber on carbon fiber “TORAYCA (registered trademark)” T800G-24K-31E, which is arranged in sheet form in one direction, by Toray Industries, Ltd., and heated and pressed. The resin was impregnated into carbon fiber to obtain a unidirectional prepreg having a weight per unit area of carbon fiber of 190 g / m ² and a mass fraction of matrix resin of 35.5%. In that case, when using the epoxy resin composition which mix | blended the thermoplastic resin particle, the following two-step impregnation method was applied, and the prepreg in which the thermoplastic resin particle was localized highly in surface layer was produced.

First, a primary prepreg containing no thermoplastic resin particles was produced. The epoxy resin composition which does not contain the thermoplastic resin particle insoluble in an epoxy resin among the raw material components of Table 1 and Table 2 was prepared in the procedure of said (1). This epoxy resin composition for primary prepreg was applied onto a release paper using a knife coater to prepare a normal resin film of 30 g / m ² for forming a basis weight of 60% by mass. Next, two sheets of resin film for this primary prepreg are overlapped on both sides of carbon fiber on Toray Industries, Ltd. product, carbon fiber "Treca (registered trademark)" T800G-24K-31E arranged in a sheet shape in one direction. Using a heat roll, the resin was impregnated with carbon fiber while heating and pressurizing at a temperature of 100 ° C. and an atmospheric pressure of 1 atm to obtain a primary prepreg.

Furthermore, in order to produce a resin film for two-stage impregnation, using a kneader, among the raw material components described in Table 1 and Table 2, 2.5 times the amount described in the thermoplastic resin particles insoluble in epoxy resin The resulting epoxy resin composition was prepared by the procedure of (1) above. The two-stage impregnating epoxy resin composition was applied onto a release paper using a knife coater to prepare a normal 20% by mass, 20 g / m ² two-stage impregnating resin film having a basis weight. This was superposed from both sides of the primary prepreg, and heated and pressurized at a temperature of 80 ° C. and an atmospheric pressure of 1 atm using a heat roll, to obtain a prepreg in which the thermoplastic resin particles are highly localized in the surface layer.

(6) Measurement of Compressive Strength of Fiber-Reinforced Composite Material: The unidirectional prepreg prepared in (5) is laminated in 12 plies with the fiber direction parallel to the compression direction, and the laminated prepreg is covered with a nylon film without gaps. In an autoclave, molding was performed at a temperature of 180 ° C. for 2 hours under a pressure of 0.59 MPa at a temperature rising rate of 1.5 ° C./min to prepare a laminate. From this laminate, a tab-attached test piece having a thickness of 2 mm, a width of 15 mm and a length of 78 mm was produced. This test piece measured 0 degree compressive strength according to JIS K 7076 (1991) using an Instron universal tester. The number of samples was n = 5.

(7) Measurement of Interlayer Toughness (G _IC ) of Fiber-Reinforced Composite Material The unidirectional prepregs produced in (5) above were laminated in 20 plies with the fiber direction aligned. However, on the center plane of lamination (between the 10 ply eye and the 11 ply eye), a fluorine resin film having a width of 40 mm and a thickness of 12.5 μm is interposed at right angles to the fiber arrangement direction. )) The laminated prepreg is covered with a nylon film without gaps, and molded in an autoclave at a temperature of 180 ° C. for 2 hours under a pressure of 0.59 MPa at a temperature rising rate of 1.5 ° C./min. A reinforced composite was formed.

  The obtained unidirectional fiber reinforced composite material was cut into a width of 20 mm and a length of 195 mm. The fiber direction was cut parallel to the length side of the sample. According to JIS K 7086 (1993), a pin load block (length 25 mm, made of aluminum) was adhered to the end of the test piece (the side across the film). A white paint was applied to both sides of the test piece to facilitate observation of crack growth.

G _IC measurement was performed according to the following procedure using the produced composite material flat plate.

According to JIS K 7086 (1993) Annex 1, tests were conducted using an Instron universal tester (manufactured by Instron). The crosshead speed was 0.5 mm / min until crack growth reached 20 mm, and 1 mm / min after 20 mm. According to JIS K 7086 (1993), from load, displacement, and crack length, Mode I interlaminar fracture toughness value of critical load at the initial stage of crack growth (G _{IC at} initial stage of crack development) and Mode I interlaminar fracture toughness of crack progress process The value was calculated. Crack growth early _{G IC} and crack propagation than 10mm measured value of 5 or more in 60mm from an average of six or more points of measurements were compared as _{G IC.}

Example 1
50 parts by weight of “Sumiepoxy (registered trademark)” ELM 434 (polyfunctional amine type epoxy resin), 50 parts by weight of GAN (bifunctional amine type epoxy resin), 155 parts by weight of B-1 (weight average molecular weight) Polysulfone-based resin [B] having a weight of 2,000 to 20,000 g / mol, 6 parts by weight of "Sumica Excel (registered trademark)" PES 5003 P (weight average molecular weight of more than 20,000 and 100,000 g / mol or less) After knead | mixing polysulfone type-resin [C], 50 mass parts of 3,3'-DAS which is epoxy resin hardening agent [D] are knead | mixed, and the epoxy resin composition was produced. The composition and the ratio are shown in Table 1 (numbers in the table represent parts by mass). About the obtained epoxy resin composition, the above-mentioned (2) viscosity (η ^* ) of epoxy resin composition, (3) flexural modulus of epoxy resin cured product, (4) toughness of epoxy resin cured product (K _IC ) (6) Measurement of compressive strength of fiber-reinforced composite material, (7) Interlaminar toughness (G _IC ) of fiber-reinforced composite material. The results are shown in Table 1.

(Examples 2 to 11)
An epoxy resin composition was produced in the same manner as in Example 1 except that the epoxy resin, polysulfone resin, other components, the epoxy resin curing agent, and the compounding amount were changed as shown in Table 1. About the obtained epoxy resin composition, it carried out similarly to Example 1, and implemented measurement. The results are shown in Table 1.

  The cured epoxy resin products obtained in Examples 1 to 11 had good elastic modulus and toughness. Further, it was revealed that the obtained epoxy resin composition had a good viscosity, had no problem in the formability of the fiber-reinforced composite material, and could sufficiently secure the compressive strength and the interlayer toughness of the fiber-reinforced composite material.

(Comparative example 1)
An epoxy resin composition was produced in the same manner as in Example 1 except that only the component (B) was used and the component (C) was not used. The toughness of the resulting cured epoxy resin product was insufficient, and the interlaminar toughness of the fiber-reinforced composite material was not at a satisfactory level.

(Comparative example 2)
An epoxy resin composition was produced in the same manner as in Example 1 except that the component [B] was not used and only the component [C] was used. The obtained epoxy resin cured product had a reduced elastic modulus and toughness, and the compressive strength and interlayer toughness of the fiber-reinforced composite material were not sufficiently expressed.

(Comparative example 3)
The comparative example 3 is an epoxy resin composition equivalent to Example 4 of patent document 2 (Unexamined-Japanese-Patent No. 2016-169381), and the epoxy resin composition was produced using the epoxy resin composition preparation method of this patent. By the fact that the component [C] was not dissolved in the epoxy resin, the elastic modulus of the cured epoxy resin was lowered, and the compressive strength of the fiber-reinforced composite material was not sufficiently expressed.

  According to the present invention, it is possible to obtain an epoxy resin cured product which maintains a high elastic modulus and has excellent toughness, and further provides a fiber-reinforced composite material excellent in interlayer toughness and compressive strength, and a prepreg. In particular, it is suitably used for structural materials. For example, in aerospace applications, for aircraft primary structural applications such as wings, tail wings and floor beams, secondary structural applications such as flaps, ailerons, cowls, fairings and interior materials, rocket motor cases and artificial satellite structural applications, etc. It is preferably used. In general industrial applications, structural materials for moving bodies such as automobiles, ships and railway vehicles, drive shafts, leaf springs, wind turbine blades, various turbines, pressure vessels, flywheels, paper rollers, roofing materials, cables, reinforcing bars, And it is used suitably for civil engineering / construction materials applications, such as repair reinforcement materials. Furthermore, in sport applications, it is suitably used for golf shafts, fishing rods, rackets applications such as tennis, badminton and squash, stick applications such as hockey, and ski pole applications.

Claims (9)

The epoxy resin composition which has following component [A]-[D], and [B] and [C] are melt | dissolving in [A].
[A] Epoxy resin [B] polysulfone resin having a weight average molecular weight of 2,000 to 20,000 g / mol, polysulfone based resin [C] having a weight average molecular weight of 20,000 and 100,000 g / mol or less [D] Epoxy resin curing agent The epoxy resin composition according to claim 1, wherein [B] and [C] are polyether sulfone. The epoxy resin composition according to claim 1 or 2, wherein 25 to 50% by mass of [B] is contained in the epoxy resin composition, and 2 to 10% by mass of [C] is contained in the epoxy resin composition. The epoxy resin composition according to any one of claims 1 to 3, wherein [B] is a polyether sulfone, and 60 mol% or more of its terminal is a hydroxyphenyl group. The epoxy resin composition according to any one of claims 1 to 4, wherein [A] comprises a polyfunctional amine type epoxy resin. The epoxy resin composition according to any one of claims 1 to 5, wherein [A] contains a bifunctional amine type epoxy resin. A prepreg obtained by impregnating a reinforcing fiber with the epoxy resin composition according to any one of claims 1 to 6. The prepreg according to claim 7, wherein the reinforcing fiber is carbon fiber. The fiber reinforced composite material containing the epoxy resin hardened material which hardens the epoxy resin composition in any one of Claims 1-6, and a reinforced fiber.