Prepreg, fiber-reinforced composites, tubular bodies made of fiber-reinforced composites, golf club shafts and fishing rods

Abstract

The objective of this invention is to provide a prepreg containing a resin composition that has excellent elastic modulus and heat resistance, as well as excellent appearance such as weather resistance or transparency, and a fiber-reinforced composite material using the prepreg that has excellent mechanical properties or heat resistance and appearance, and a tubular body, golf club shaft, or fishing rod made of the fiber-reinforced composite material. As a solution thereto, a prepreg is provided that includes reinforcing fibers and a resin composition, wherein the resin composition in the prepreg contains the following components [A] to [D] and satisfies the following conditions (1) to (5). Component [A]: Phenolic varnish-type epoxy resin Component [B]: Oxazolidinone type epoxy resin Ingredient [C]: Any one or both of sorbitol-based epoxy resin and glycerol-based epoxy resin. Ingredient [D]: Dicyandiamine Condition (1): The content of component [A] is 20 to 50 parts by mass relative to 100 parts by mass of all epoxy resin. Condition (2): The content of component [B] is 10 to 40 parts by mass relative to 100 parts by mass of all epoxy resin. Condition (3): The content of component [C] is 10 to 40 parts by mass relative to 100 parts by mass of all epoxy resin. Condition (4): Of all 100 parts by weight of epoxy resin, there are at least 40 parts by weight of component [B] and component [C]. Condition (5): Does not contain component [E]: glycidylamine type epoxy resin, or if it is contained, it is less than 10 parts by weight relative to 100 parts by weight of all epoxy resin.

Description

Technical Field

[0001] The present invention relates to a fiber-reinforced composite material prepreg, a fiber-reinforced composite material, and a fiber-reinforced composite material tubular body suitable for aerospace applications, general industrial applications, and sports applications, and also to a golf club shaft or fishing rod made using the fiber-reinforced composite material tubular body. Prior Art

[0002] Fiber-reinforced composite materials using carbon fibers or polyaramid fibers as reinforcing fibers are widely used for structural materials in aircraft and automobiles, as well as in sports and general industrial applications such as tennis rackets, golf club shafts, fishing rods, bicycles, and frames, due to their high specific strength and specific elastic modulus. Thermosetting resins are primarily used as the resin composition for these fiber-reinforced composite materials from the perspectives of heat resistance and productivity, with epoxy resins being particularly preferred due to their mechanical properties, such as adhesion to the reinforcing fibers.

[0003] In recent years, fiber-reinforced composite materials have been increasingly being used in applications such as golf club shafts, fishing rods, and bicycles, where further lightweighting is required. For example, in order to achieve excellent bending strength in tubular bodies like golf club shafts and fishing rods, the fiber-reinforced composite materials used require high strength in both the fiber-direction and non-fiber-direction directions. However, these strengths significantly affect the strength and elastic modulus of the epoxy resin itself, which is used as the matrix resin. Furthermore, when fiber-reinforced composite materials are processed into final products, they also require high heat resistance to withstand the processing heat. Furthermore, the use of clear coatings on the surface of fiber-reinforced composite materials, such as the cross-linking of the reinforcing fibers, as design elements, is also increasing. Therefore, for epoxy resins used as matrix resins, in addition to excellent mechanical properties and heat resistance in the cured product, the cured product's appearance, such as weather resistance and transparency, is also highly valued.

[0004] Patent Document 1 studies a composition combining an oxazolidone-type epoxy resin and a novolac-type epoxy resin, aiming to achieve a balance between mechanical properties and heat resistance. Patent Document 2 also studies a prepreg that, by using an epoxy resin composition with a parallel light transmittance of 30% or greater, eliminates whitening due to moisture absorption and provides an excellent appearance for fiber-reinforced composite materials. Furthermore, Patent Document 3 studies a tow prepreg that combines a dissolution accelerator, such as a sorbitol-type epoxy resin, to reduce the risk of residual dissolution of dicyandiamide used as a hardener, resulting in excellent fracture strain and transparency. [Prior art literature] [Patent Document]

[0005] Patent Document 1: International Publication No. 2020 / 080474 Patent Document 2: Japanese Patent Application Laid-Open No. 2003-261744 Patent Document 3: Japanese Patent Application Publication No. 2020-158594 Summary of the Invention

[0006] [Problems to be solved by the invention] While the technology in Patent Document 1 achieves both elastic modulus and heat resistance, it lacks consideration for appearance properties such as weather resistance and transparency, making it impossible to consistently achieve an excellent appearance. Furthermore, while the technology in Patent Document 2 achieves a cured resin with excellent transparency or a molded article free of whitening due to moisture absorption, the cured resin has a low elastic modulus, which does not necessarily result in excellent mechanical properties in fiber-reinforced composite materials. Furthermore, Patent Document 2 makes no consideration of weather resistance, leaving room for improvement. While Patent Document 3 achieves a cured resin with excellent transparency, it also has low elastic modulus and heat resistance, which does not necessarily result in excellent mechanical properties or heat resistance in fiber-reinforced composite materials. Furthermore, Patent Document 3 also lacks consideration of weather resistance, making it impossible to consistently achieve excellent weather resistance.

[0007] Therefore, the present invention aims to provide a prepreg comprising a resin composition having excellent elastic modulus and heat resistance, and also excellent appearance such as weather resistance and transparency, as well as a fiber-reinforced composite material using the prepreg, excellent mechanical properties, heat resistance, and appearance, a fiber-reinforced composite material tubular body, a golf club shaft, and a fishing rod. [Methods for solving the problem]

[0008] 1. A prepreg comprising reinforcing fibers and a resin composition, wherein the resin composition comprises the following components [A] to [D] and satisfies the following conditions (1) to (5). Ingredient [A]: Novolac type epoxy resin Component [B]: Oxazolidinone-type epoxy resin Ingredient [C]: either or both of sorbitol-based epoxy resin and glycerin-based epoxy resin Ingredient [D]: dicyandiamide Condition (1): The content of component [A] is 20 to 50 parts by mass based on 100 parts by mass of the total epoxy resin. Condition (2): The content of component [B] is 10 to 40 parts by mass relative to 100 parts by mass of the total epoxy resin. Condition (3): The content of component [C] is 10 to 40 parts by mass relative to 100 parts by mass of the total epoxy resin. Condition (4): 100 parts by mass of the total epoxy resin contains 40 parts by mass or more of component [B] and component [C]. Condition (5): Component [E]: glycidylamine type epoxy resin is not contained, or even if contained, the amount thereof is 10 parts by mass or less relative to 100 parts by mass of the total epoxy resin. 2. The prepreg according to item 1 above, wherein the component [E] is not contained, or even if the component [E] is contained, the content thereof is 1 part by mass or less relative to 100 parts by mass of the total epoxy resin. 3. The prepreg according to 1 or 2 above, comprising component [F]: a compound having a boiling point of 130° C. or higher and a molecular weight m of 50 to 250, having no epoxy group in the molecule, and having no curing ability of epoxy resin. 4. The prepreg according to any one of 1 to 3 above, comprising component [G]: a phenoxy resin as the thermoplastic resin. 5. A fiber-reinforced composite material obtained by curing the prepreg according to any one of 1 to 4 above. 6. A fiber-reinforced composite tubular body obtained by molding the prepreg according to any one of 1 to 4 above. 7. A golf club shaft, which is obtained by manufacturing a tubular body using the fiber-reinforced composite material according to 6 above. 8. A fishing rod, which is obtained by using the fiber-reinforced composite material according to 6 above to make a tubular body. [Effects of the Invention]

[0009] The present invention provides a prepreg comprising a resin composition having excellent elastic modulus and heat resistance, as well as excellent appearance such as weather resistance and transparency; a fiber-reinforced composite material using the prepreg, having excellent mechanical properties, heat resistance, and appearance; a fiber-reinforced composite tubular body; a golf club shaft; and a fishing rod. Implementation Method

[0010] Hereinafter, the present invention will be described in detail.

[0011] The prepreg of the present invention comprises a resin composition and reinforcing fibers. Preferably, the prepreg comprises a resin composition and reinforcing fibers. The resin composition comprises components [A] to [D] as essential components.

[0012] Component [A] in this invention is a novolac-type epoxy resin. The inclusion of component [A] improves the elastic modulus and heat resistance of the cured resin without compromising weather resistance, resulting in a fiber-reinforced composite material with excellent mechanical properties, heat resistance, and appearance.

[0013] The resin composition should contain 20 to 50 parts by mass of component [A] per 100 parts by mass of the total epoxy resin. The lower limit is preferably 25 parts by mass or greater, and more preferably 30 parts by mass or greater. The upper limit is preferably 45 parts by mass or less, and more preferably 40 parts by mass or less. By containing component [A] within this range, the cured resin exhibits excellent transparency and a good balance between mechanical properties, heat resistance, and appearance.

[0014] In order to achieve a good balance between the flexural modulus and heat resistance of the cured resin, the lower limit of the softening point of the novolac epoxy resin is preferably 50°C or higher, more preferably 60°C or higher. The upper limit of the softening point is preferably 120°C or lower, more preferably 110°C or lower.

[0015] As component [A], phenol novolac type epoxy resin and cresol novolac type epoxy resin can be mentioned.

[0016] Commercially available products of phenol novolac-type epoxy resins include jER (registered trademark) 152 and jER (registered trademark) 154 (both manufactured by Mitsubishi Chemical Corporation), EPPN-201 (manufactured by Nippon Kayaku Co., Ltd.), EPICLON (registered trademark) N-740 and EPICLON (registered trademark) N-770 (softening point: 70°C), and EPICLON (registered trademark) N-775 (softening point: 75°C or higher, manufactured by DIC Corporation).

[0017] Commercially available products of cresol novolac-type epoxy resins include EPICLON (registered trademark) N-660 (softening point: 66°C), EPICLON (registered trademark) N-665 (softening point: 70°C), EPICLON (registered trademark) N-670 (softening point: 73°C), EPICLON (registered trademark) N-673 (softening point: 78°C), EPICLON (registered trademark) N-680 (softening point: 87°C), EPICLON (registered trademark) N-690 (softening point: 93°C), and EPICLON (registered trademark) N-695 (softening point: 95°C or higher, manufactured by DIC Corporation).

[0018] Component [B] in the present invention is an oxazolidinone-type epoxy resin. The inclusion of component [B] improves the heat resistance of the cured resin without compromising weather resistance. Furthermore, the inclusion of component [B] promotes the dissolution of dicyandiamide (component [D]), improving the transparency of the cured resin. In other words, the inclusion of component [B] enables the production of a fiber-reinforced composite material with excellent heat resistance and appearance.

[0019] The resin composition should contain 10 to 40 parts by mass of component [B] per 100 parts by mass of the total epoxy resin. The lower limit is preferably 15 parts by mass or greater, and more preferably 20 parts by mass or greater. The upper limit is preferably 35 parts by mass or less, and more preferably 30 parts by mass or less. When the content of component [B] is at least the lower limit, the cured resin exhibits excellent heat resistance and transparency. When the content of component [B] is at or below the upper limit, the flexural modulus of the cured resin is not impaired. In other words, by containing component [B] within the above range, the cured resin exhibits a good balance between transparency, heat resistance, and flexural modulus.

[0020] As commercially available products of component [B], AER4152, AER4151 (both manufactured by Asahi Kasei Chemicals Co., Ltd.), "DER (registered trademark)" 852, "DER (registered trademark)" 858 (both manufactured by Dow Chemical Co., Ltd.), TSR-400 (manufactured by DIC Co., Ltd.), ACR1348 (manufactured by ADEKA Co., Ltd.), etc. can be used.

[0021] Component [C] in the present invention is either or both of a sorbitol-type epoxy resin and a glycerin-type epoxy resin. Furthermore, when both are included, they are considered component [C]. These resins may be used alone or in combination. The inclusion of component [C] improves the flexural modulus of the cured resin without compromising weather resistance. Furthermore, component [C] has hydroxyl groups in its molecular structure, resulting in high polarity, which promotes the dissolution of dicyandiamide (component [D]), thereby improving the transparency of the cured resin. Specifically, the inclusion of component [C] allows for a fiber-reinforced composite material with excellent flexural modulus and appearance.

[0022] The resin composition should contain 10 to 40 parts by mass of component [C] per 100 parts by mass of the total epoxy resin. The lower limit is preferably 15 parts by mass or greater, and more preferably 20 parts by mass or greater. The upper limit is preferably 35 parts by mass or less, and more preferably 30 parts by mass or less. When the content of component [C] is at or above the lower limit, the cured resin exhibits excellent flexural modulus and transparency. When the content of component [C] is at or below the upper limit, the cured resin exhibits no deterioration in heat resistance. In other words, by containing component [C] within the above range, the cured resin exhibits a good balance between transparency, heat resistance, and flexural modulus.

[0023] Examples of the glycerin-type epoxy resin as component [C] include monoglycerin-type epoxy resins, diglycerin-type epoxy resins, and polyglycerin-type epoxy resins.

[0024] Commercially available products of sorbitol-based epoxy resins include Denacol (registered trademark) EX-612, Denacol (registered trademark) EX-614, Denacol (registered trademark) EX-614B, and Denacol (registered trademark) EX-622 (all manufactured by Nagase ChemteX Co., Ltd.).

[0025] Commercially available products of glycerin-based epoxy resins include Denacol (registered trademark) EX-313 and Denacol (registered trademark) EX-314 (both manufactured by Nagase ChemteX Co., Ltd.). Commercially available products of diglycerin-based epoxy resins include Denacol (registered trademark) EX-421 (manufactured by Nagase ChemteX Co., Ltd.). Commercially available products of polyglycerin-based epoxy resins include Denacol (registered trademark) EX-512 and Denacol (registered trademark) EX-521 (both manufactured by Nagase ChemteX Co., Ltd.).

[0026] As condition (4) in the present invention, the total content of component [B] and component [C] needs to be 40 parts by mass or more relative to 100 parts by mass of the total epoxy resin. The lower limit is preferably 45 parts by mass or more, and more preferably 50 parts by mass or more. In addition, regarding the upper limit, the total upper limit of each component in conditions (2) and (3) is 80 parts by mass or less, but preferably 70 parts by mass or less, and more preferably 60 parts by mass or less. By setting the total content of component [B] and component [C] relative to 100 parts by mass of the total epoxy resin to be within the above range, the transparency of the cured resin is greatly improved, and a fiber-reinforced composite material with excellent appearance (improved white turbidity) can be obtained.

[0027] As condition (5) in the present invention, the glycidylamine-type epoxy resin as component [E] is not included, or even if the glycidylamine-type epoxy resin as component [E] is included, it is required to be 10 parts by mass or less relative to 100 parts by mass of the total epoxy resin. Furthermore, even if component [E] is included, it is more preferably 5 parts by mass or less, and even more preferably 1 part by mass or less. By setting the blending amount of component [E] to 10 parts by mass or less, a fiber-reinforced composite material having excellent weather resistance can be obtained without hindering the improvement of the weather resistance of the cured resin.

[0028] Examples of the glycidylamine epoxy resin as component [E] include glycidylamine epoxy resins having an aromatic ring and aliphatic glycidylamine epoxy resins, such as diaminodiphenylmethane epoxy resins, diaminodiphenylsulfone epoxy resins, aminophenol epoxy resins, m-xylenediamine epoxy resins, and 1,3-bisaminomethylcyclohexane epoxy resins.

[0029] Examples of commercially available diaminodiphenylmethane epoxy resins include ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), ARALDITE (registered trademark) MY720, ARALDITE (registered trademark) MY721, ARALDITE (registered trademark) MY9512, and ARALDITE (registered trademark) MY9663 (all manufactured by Huntsman Advanced Materials Co., Ltd.), Epotohto (registered trademark) YH-434 (manufactured by Nippon Steel Chemicals & Materials Co., Ltd.), and jER (registered trademark) 604 (manufactured by Mitsubishi Chemical Co., Ltd.).

[0030] Examples of commercially available products of diaminodiphenylsulfonium-based epoxy resins include TG3DAS (manufactured by Mitsui Fine Chemicals Co., Ltd.).

[0031] Commercially available aminophenol-type epoxy resins include ELM120 and ELM100 (both manufactured by Sumitomo Chemical Co., Ltd.), jER (registered trademark) 630 (manufactured by Mitsubishi Chemical Co., Ltd.), Araldite (registered trademark) MY0500, Araldite (registered trademark) MY0510, Araldite (registered trademark) MY0600, and Araldite (registered trademark) MY0610 (all manufactured by Huntsman Advanced Materials Co., Ltd.).

[0032] Examples of commercially available meta-xylenediamine epoxy resins include "TETRAD (registered trademark)"-X (manufactured by Mitsubishi Gas Chemical Co., Ltd.).

[0033] Examples of commercially available 1,3-bisaminomethylcyclohexane-based epoxy resins include "TETRAD (registered trademark)"-C (manufactured by Mitsubishi Gas Chemical Co., Ltd.).

[0034] Epoxy resins other than those listed above may be appropriately blended into the resin composition used in the present invention, as long as the effects of the present invention are not impaired. Specifically, examples include bisphenol-type, isocyanuric acid-type, dicyclopentadiene-type, hydantoin-type, trimethylolpropane-type, pentaerythritol-type, trihydroxyphenylmethane-type, and tetraphenylethane-type epoxy resins.

[0035] Among them, commercially available products of bisphenol A type epoxy resin include "jER (registered trademark)" 825, "jER (registered trademark)" 828, "jER (registered trademark)" 834, "jER (registered trademark)" 1001, "jER (registered trademark)" 1002, "jER (registered trademark)" 1003, "jER (registered trademark)" 1003F, "jER (registered trademark)" 1004, "jER (registered trademark)" 1004AF, "jER (registered trademark)" 1005F, "jER (registered trademark)" 1006FS, jER (registered trademark) 1007, jER (registered trademark) 1009, jER (registered trademark) 1010 (all manufactured by Mitsubishi Chemical Co., Ltd.), EPICLON (registered trademark) 850 (manufactured by DIC Corporation), Epotohto (registered trademark) YD-128 (manufactured by Nippon Steel Chemical & Materials Co., Ltd.), and DER (registered trademark) -331 and DER (registered trademark) -332 (all manufactured by Dow Chemical Co., Ltd.), etc.

[0036] Examples of commercially available bisphenol F-type epoxy resins include Araldite (registered trademark) GY282 (manufactured by Huntsman Advanced Materials), jER (registered trademark) 806, jER (registered trademark) 807, jER (registered trademark) 4005P, jER (registered trademark) 4007P, and jER (registered trademark) 4010P (all manufactured by Mitsubishi Chemical Corporation), EPICLON (registered trademark) 830 (manufactured by DIC Corporation), and Epotohto (registered trademark) YD-170 (manufactured by Nippon Steel Chemicals & Materials Co., Ltd.).

[0037] Component [D] in the present invention is dicyandiamide. Dicyandiamide excels in providing high mechanical properties and heat resistance to cured epoxy resins and is widely used as a hardener for various epoxy resins. Furthermore, it is advantageously used because epoxy resin compositions exhibit excellent weather resistance and storage stability. Commercially available dicyandiamide products include DICY7 and DICY15 (both manufactured by Mitsubishi Chemical Corporation).

[0038] In the present invention, the content of component [D] is preferably 4 to 12 parts by mass per 100 parts by mass of the total epoxy resin, from the perspective of achieving an excellent balance between mechanical properties, heat resistance, and transparency in the cured resin. The lower limit is more preferably 5 parts by mass or more, and the upper limit is more preferably 10 parts by mass or less.

[0039] From the perspective of controlling the viscosity of the resin composition or the tackiness of the prepreg, the resin composition used in the prepreg of the present invention preferably contains a phenoxy resin as component [G]. The phenoxy resin is preferably formulated to produce a prepreg with excellent handleability so as to increase the viscosity of the resin composition or the tackiness of the prepreg without impairing the weather resistance of the cured resin.

[0040] Examples of commercially available phenoxy resins include "Phenototo (registered trademark)" YP-50, "Phenototo (registered trademark)" YP-50S, and "Phenototo (registered trademark)" YP-70 (all manufactured by Nippon Steel Chemicals & Materials Co., Ltd.).

[0041] To control the curing rate, a curing accelerator may be added to the resin composition used in the prepreg of the present invention. Examples of curing accelerators include urea compounds and imidazole compounds. Urea compounds are particularly preferred for the storage stability of the resin composition.

[0042] Examples of urea compounds include 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, phenyldimethylurea, and toluenebisdimethylurea. Commercially available aromatic urea compounds include DCMU99 (manufactured by Hodogaya Chemical Industry Co., Ltd.) and Omicure (registered trademark) 24 (manufactured by PTI Japan Co., Ltd.).

[0043] To increase the elastic modulus of the cured resin, the resin composition used in the present invention preferably includes, as component [F], a compound having a boiling point of 130°C or higher, a molecular weight m of 50 or higher and 250 or lower, and having no epoxy groups in the molecule and no epoxy resin curing ability. Compounds such as amines or phenols that undergo addition reactions with epoxy resins, acid anhydrides that copolymerize with epoxy resins, imidazoles that serve as epoxy resin self-polymerization initiators, aromatic urea compounds, and tertiary amine compounds are compounds that have epoxy resin curing ability and are not included in component [F]. "No epoxy resin curing ability" here refers to the property of not chemically reacting with epoxy resins and not participating in epoxy resin self-polymerization.

[0044] It is believed that component [F] does not enter the crosslinked structure formed by the reaction between the epoxy resin and dicyandiamide, but rather resides in the interstices therein. This state is maintained even after the epoxy resin cures, which is believed to contribute to the higher elastic modulus of the resulting cured resin. Furthermore, surprisingly, by blending component [F], a cured resin having not only a high elastic modulus but also high elongation and strength can be obtained.

[0045] Furthermore, by having a boiling point of 130°C or higher, more preferably 180°C or higher, component [F] can suppress volatilization during curing of the resin composition, thereby producing a cured resin or fiber-reinforced composite material with excellent mechanical properties. Setting the boiling point of component [F] within this range is also preferred because it suppresses the formation of voids in the resulting fiber-reinforced composite material and reduces the deterioration of mechanical properties. While there is no particular upper limit on the boiling point of component [F], the boiling points of compounds commonly used in the present invention are generally 400°C or lower.

[0046] The component [F] is preferably contained in an amount of 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, and even more preferably 3 to 6 parts by mass, based on 100 parts by mass of the total epoxy resin.

[0047] The molecular weight m of component [F] is 50 or more and 250 or less, more preferably 70 or more and 120 or less. By setting the molecular weight of component [F] within this range, component [F] is appropriately retained in the voids of the crosslinked structure formed by the reaction of the epoxy resin and dicyandiamide, and a cured product having excellent elastic modulus, strength, and elongation can be obtained.

[0048] In the present invention, the ingredient [F] is preferably a compound having at least one functional group within the molecule selected from the group consisting of amide groups, ketone groups, and hydroxyl groups. In the case where component [F] has highly polar functional groups within the molecule as described above, a strong intermolecular interaction is generated between the hydroxyl group and component [F] in the cross-linked structure formed by epoxy resin and dicyanodiamine. In addition, in the case where component [F] has a highly polar functional group as mentioned above, it can promote the dissolution of dicyanodiamine as component [D] and improve the transparency of the resin hardener.

[0049] As said components [F], enumerated are: N-methylformamide, N-methylacetamide, 2-pyrrolidinone, N-methylpropylamine, N-ethylacetamide, N-methylacetylaniline, N,N'-diphenylacetamide, and other amides such as ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexanediol, and heptanediol. The compounds may be used alone or in a suitable formulation.

[0050] As reinforced fibers used in the prepreg and fiber-reinforced composites of the present invention, they may preferably be enumerated: carbon fiber, graphite fiber, polyarylamide fiber, glass fiber, etc., especially carbon fiber. There is no restriction on the morphology or arrangement of the reinforced fibers, for example, long fibers pulled together in one direction, single bundles of yarn, fabrics, knitwear and fibrous structures such as silk cords can be used. As reinforced fibers, more than two types of carbon fiber, or glass fiber, polyarylamine fiber, boron fiber, poly-p-phenylene benzobisoxazole (PBO) fiber, high-strength polyethylene fiber, alumina fiber and silicon carbide fiber can also be used in combination.

[0051] As carbon fibers, specifically include: acrylic-based, asphalt-based and acrylic-based carbon fibers, especially acrylic-based carbon fibers with high tensile strength can be better used.

[0052] As the form of carbon fiber, can be used with yarn, unpinned yarn and without yarn. In the case of yarn, the alignment of the filaments constituting the carbon fiber is not parallel, thus resulting in a decrease in the mechanical characteristics of the obtained carbon fiber reinforced composites.

[0053] The tensile modulus of carbon fiber is preferably in the range of 200 GPa to 440 GPa. The tensile modulus of carbon fiber is affected by the crystallinity of the graphite structure that constitutes the carbon fiber; higher crystallinity results in higher modulus. This range is preferred because it provides a high balance of rigidity and strength in the carbon fiber-reinforced composite material. A more preferred modulus is in the range of 230 GPa to 400 GPa, and even more preferably, in the range of 260 GPa to 370 GPa. The tensile modulus of carbon fiber is measured in accordance with Japanese Industrial Standards (JIS) R7601 (2006).

[0054] The prepreg of the present invention can be produced using various known methods. For example, the prepreg can be produced by a hot melt method, which involves heating a resin composition to reduce its viscosity without using an organic solvent, and then impregnating the resin composition into reinforcing fibers.

[0055] In the hot melt method, the following methods can be used: a method in which a resin composition whose viscosity has been reduced by heating is directly impregnated into the reinforcing fibers; or a method in which the resin composition is first temporarily coated on a release paper or the like to form a release paper sheet with a resin film, and then the resin film is overlapped on the reinforcing fibers from both sides or one side, and heated and pressurized to impregnate the reinforcing fibers with the resin composition.

[0056] The reinforcing fiber content in the prepreg is preferably 30% to 90% by mass, more preferably 35% to 85% by mass, and even more preferably 65% ​​to 85% by mass. If the fiber content is too low, the amount of resin is excessive, making it difficult to achieve the advantages of fiber-reinforced composite materials, which have excellent specific strength and specific elastic modulus. Furthermore, during the curing of fiber-reinforced composite materials, the heat generated during molding may be too high. On the other hand, if the fiber content is too high, resin impregnation may be poor, and the resulting composite material may be porous. Furthermore, the viscosity of the prepreg may be impaired.

[0057] The fiber-reinforced composite material or fiber-reinforced composite material tubular article of the present invention can be produced, for example, by laminating the prepregs of the present invention in a predetermined configuration and applying pressure and heat to cure the resin. The heat and pressure application method may include press molding, autoclave molding, bagging, wrapping tape, or internal pressure molding.

[0058] The tape wrapping method is particularly suitable for forming tubular bodies made of fiber-reinforced composite materials. The tape wrapping method involves wrapping a prepreg around a core rod, such as a mandrel, to produce a cylindrical molded body. Specifically, the prepreg is wrapped around the mandrel, and a tape comprising a thermoplastic resin film is wrapped around the mandrel to secure and apply pressure to the prepreg. After the resin is heated and cured in an oven, the mandrel is removed to produce a cylindrical molded body. This method is particularly suitable for producing tubular bodies such as golf club shafts and fishing rods.

[0059] When the resin composition of the present invention is used, its cured product has excellent mechanical properties, weather resistance, and transparency. Therefore, the fiber-reinforced composite tubular body of the present invention exhibits excellent bending strength, weather resistance, and appearance.

[0060] The fiber-reinforced composite material or fiber-reinforced composite tubular body of the present invention can be widely used in aerospace, general industrial, and sports applications. More specifically, in general industrial applications, it can be suitably used in structures such as automobiles, ships, and railway vehicles. In sports applications, it can be suitably used in golf club shafts, fishing rods, and tennis or badminton rackets. The fiber-reinforced composite tubular body of the present invention is particularly preferably used in golf club shafts and fishing rods.

[0061] Unless otherwise specified, the upper and lower limits of the numerical ranges described above can be combined arbitrarily. [Example]

[0062] The present invention is described in detail below using examples. However, the scope of the present invention is not limited to these examples. Furthermore, the unit "parts" for composition ratios refers to parts by mass unless otherwise specified. Furthermore, unless otherwise specified, measurements of various characteristics (physical properties) were performed at a temperature of 23°C and a relative humidity of 50%. The amounts of each component in the table are expressed in parts by mass.

[0063] <Materials used in Examples and Comparative Examples> (1) Reinforced fiber TORAYCA (registered trademark) T1100G-24K (24,000 fibers, tensile modulus: 324 GPa, density: 1.8 g / cm³, manufactured by Toray Industries, Inc.) (2) Epoxy resin Component [A]: Novolac type epoxy resin [A]-1 EPICLON (registered trademark) N-775 (phenol novolac type epoxy resin, epoxy equivalent: 189, manufactured by DIC Corporation of China) [A]-2 EPICLON (registered trademark) N-695 (cresol novolac type epoxy resin, epoxy equivalent: 214, manufactured by DIC Corporation of China) Component [B]: Oxazolidinone-type epoxy resin [B]-1 "DER (registered trademark)" 858 (epoxy equivalent: 400, manufactured by Dow Chemical Co., Ltd.) Component [C]: Sorbitol-based epoxy resin, glycerin-based epoxy resin [C]-1 Denacol (registered trademark) EX-614B (sorbitol-based epoxy resin, epoxy equivalent: 173, manufactured by Nagase ChemteX Co., Ltd.) [C]-2 Denacol (registered trademark) EX-512 (polyglycerol-type epoxy resin, epoxy equivalent: 168, manufactured by Nagase ChemteX Co., Ltd.) Component [E]: Glycidylamine type epoxy resin [E]-1 Araldite (registered trademark) MY0600 (aminophenol-based epoxy resin, epoxy equivalent weight: 118, manufactured by Huntsman Advanced Materials) Component [H]: Other epoxy resins [H]-1 EPICLON (registered trademark) 830 (bisphenol F epoxy resin, epoxy equivalent: 172, manufactured by DIC Corporation of China) [H]-2 Denacol (registered trademark) EX-411 (pentaerythritol-based epoxy resin, epoxy equivalent: 229, manufactured by Nagase ChemteX Co., Ltd.) (3) Component [D]: dicyandiamide [D]-1 DICY7 (dicyandiamide, manufactured by Mitsubishi Chemical Co., Ltd.) (4) Component [F]: a compound having a boiling point of 130°C or higher and a molecular weight m of 50 or higher and 250 or lower, and having no epoxy group in the molecule and no epoxy resin curing ability [F]-1 2-Pyrrolidone (boiling point: 245°C, molecular weight m: 85, manufactured by Tokyo Chemical Industry Co., Ltd.) [F]-2 1,2-Propanediol (boiling point: 188°C, molecular weight m: 76, manufactured by Tokyo Chemical Industry Co., Ltd.) (5) Component [G]: phenoxy resin [G]-1 Phenototo (registered trademark) YP-70 (manufactured by Nippon Steel Chemicals & Materials Co., Ltd.) (6) Hardening accelerator DCMU99 (3-(3,4-dichlorophenyl)-1,1-dimethylurea, manufactured by Hodogaya Chemical Industry Co., Ltd.).

[0064] <Method for Preparing Resin Composition> (1) Preparation of hardener masterbatch Prepare 10 parts by mass (10 parts by mass per 100 parts by mass of the total epoxy resin) of an epoxy resin that is liquid at room temperature (this corresponds to [C]-1, [C]-2, [H]-1, and [H]-2). Add dicyandiamide (component [D]) to each of these components and knead them at room temperature. Pass the mixture through a three-roll mill twice to prepare a hardener masterbatch.

[0065] (2) Preparation of resin composition 90 parts by mass of the total epoxy resin, excluding 10 parts by mass of the liquid epoxy resin used in (1), were placed in a beaker. While kneading, the temperature was raised to 150°C, and then component [G]: phenoxy resin was added. Heat-kneading was performed at 150°C for 1 hour to dissolve the resin. Next, while continuing to knead, the temperature was lowered to 55°C to 65°C, and the hardener masterbatch prepared in (1) and component [F] having the components and amounts shown in the table were added. A hardening accelerator was also added, and the mixture was kneaded at the same temperature for 30 minutes to obtain a resin composition. Tables 1 to 5 show the compositions of the Examples and Comparative Examples.

[0066] <Method for producing cured resin> The resin composition prepared according to the above-described "Resin Composition Preparation Method" was degassed in a vacuum and then heated in a mold set to a thickness of 2 mm via a 2 mm thick Teflon (registered trademark) spacer. The temperature was raised from 30°C at a rate of 1.7°C / minute to 90°C, where it was held for 1 hour. The temperature was then raised at a rate of 2.0°C / minute to 135°C, where it was cured for 2 hours to obtain a 2 mm thick plate-shaped cured resin product.

[0067] For appearance evaluation, the curing reaction was conducted in a mold set to a thickness of 1 mm with a 1 mm thick Teflon (registered trademark) spacer interposed therebetween to obtain a 1 mm thick plate-shaped cured resin product.

[0068] <Prepreg Production Method> The resin composition prepared according to the "Resin Composition Preparation Method" was applied to release paper using a knife coater to produce two resin films with a resin basis weight of 31 g / m². Next, the resin films were stacked on both sides of reinforcing fibers (TORAYCA (registered trademark) T1100G-24K) arranged in one direction to form a sheet with a fiber basis weight of 125 g / m². The sheets were then impregnated with the resin composition under heating and pressure at a temperature of 110°C and a maximum pressure of 2 MPa, producing prepregs.

[0069] <Various Evaluation Methods> (1) Three-point bending test of cured resin Test pieces 10 mm wide and 60 mm long were cut from the 2 mm thick cured resin produced according to the "Preparation Method of Cured Resin Product" described above. Three-point bending was performed in accordance with JIS K7171 (1994) using an INSTRON universal testing machine (manufactured by INSTRON Corporation) with a span of 32 mm, a crosshead speed of 2.5 mm / min, and a sample size of n = 6. The average value of the elastic modulus obtained at this time was defined as the flexural elastic modulus of the cured resin product.

[0070] (2) Determination of glass transition temperature of cured resin A test piece 12.7 mm wide and 55 mm long was cut from the 2 mm thick cured resin produced according to the "Preparation Method for a Cured Resin Product" described above. Dynamic mechanical analysis (DMA) measurements were performed on these test pieces using a viscoelasticity analyzer (ARES, manufactured by TA Instruments) at a torsional vibration frequency of 1.0 Hz and a heating rate of 5.0°C / min over a temperature range of 40°C to 250°C. The glass transition temperature was measured. The glass transition temperature was defined as the temperature at the intersection of the tangent line in the glass state and the tangent line in the transition state on the storage modulus G' curve.

[0071] (3) Transparency evaluation of cured resin A 1mm thick cured resin prepared according to the "Preparation Method for a Cured Resin Material" was placed on a piece of paper with written text. The transparency of the cured resin was confirmed by subjects with visual acuity of approximately 1.0 as measured using a Landolt ring chart. A value was assigned for clarity of the text, as before placement of the cured resin; B for clarity of text, though hazy; and C for complete inability to read.

[0072] (4) Weather resistance test of cured resin A test piece 37 mm wide and 68 mm long was cut from the 1 mm thick cured resin produced according to the "Preparation Method of Cured Resin Product" described above. This test piece was subjected to an accelerated weathering test (Super Xenon Weather Meter SX-75, manufactured by Suga Test Instruments Co., Ltd.). The test piece was irradiated at an intensity of 180 W / m², a black panel temperature of 63°C, and a humidity of 50% RH without water spray for 102 minutes, followed by irradiation at an intensity of 180 W / m², a tank temperature of 28°C, and a humidity of 99% RH with water spray for 18 minutes. This cycle was repeated 12 times (i.e., for 24 hours).

[0073] Weather resistance was evaluated by measuring the color difference (ΔE) of the cured product before and after the weathering test using a multi-light source spectrophotometer MSC-P (manufactured by Suga Test Instruments Co., Ltd.). Tristimulus values ​​(L*, a*, and b*) were determined using a reflectance method using a D65 illuminant, a 10° field of view, and optical conditions of d / 8 with specular reflection removed. The color difference (ΔE) was calculated using the following formula (I) using the differences in the tristimulus values ​​before and after the weathering test (ΔL*, Δa*, and Δb*).

[0074] ΔE={(ΔL*) 2+(Δa*) 2+(Δb*) 2} 1 / 2･･･(I).

[0075] (5) Weather resistance test of fiber reinforced composite materials The prepreg prepared in the "Prepreg Preparation Method" was stacked 20 layers with the fibers aligned in the same direction. The temperature was then raised from 30°C to 90°C at a rate of 1.7°C / minute in an autoclave under a pressure of 0.7 MPa. After maintaining the temperature at 90°C for 60 minutes, the temperature was raised to 135°C at a rate of 2.0°C / minute and formed at 135°C for 120 minutes. This produced a 2 mm thick unidirectional carbon fiber reinforced polymer composite (CFRP) sheet. A test specimen with a width of 37 mm and a length of 68 mm was cut from the sheet. The specimen was placed outdoors in a sheltered, sun-exposed, and unshaded location for two months, where it was subjected to a weathering test. The test pieces before and after the weathering test were arranged horizontally, and 10 subjects were asked about the color difference. If 8 or more of the 10 subjects answered "no color change" or "unclear color change", the evaluation was "0". If 3 or more subjects answered "color change", the evaluation was "×".

[0076] <Example 1> A resin composition was prepared according to the above-described "Resin Composition Preparation Method" using: 35 parts by mass of "EPICLON (registered trademark)" N-775 as component [A] of the epoxy resin; 25 parts by mass of "DER (registered trademark)" 858 as component [B]; 20 parts by mass of "Denacol (registered trademark)" EX-614B as component [C]; 20 parts by mass of "EPICLON (registered trademark)" 830 as another epoxy resin (component [H]); 5.8 parts by mass of DICY7 (dicyandiamide) as component [D]; 3 parts by mass of "Phenototo (registered trademark)" YP-70 (phenoxy resin) as component [G]; and 3 parts by mass of DCMU99 as a curing accelerator.

[0077] A cured resin was prepared from the obtained resin composition according to the <Preparation Method for a Cured Product>. The flexural modulus, glass transition temperature, transparency, and weather resistance (color difference ΔE) of the cured resin were measured. The results showed a flexural modulus of 4.0 GPa, a glass transition temperature of 140°C, a transparency of A, and a color difference ΔE of 6.7, indicating that the cured resin had good physical properties and appearance.

[0078] Furthermore, when a prepreg was prepared from the obtained resin composition according to the <Prepreg Preparation Method> and measured according to "(5) Weather resistance of fiber-reinforced composite material" in the <Various Evaluation Methods>, the fiber-reinforced composite material had good weather resistance.

[0079] <Example 2 to Example 14> A cured resin product and prepreg were prepared using the same method as in Example 1, except that the composition was changed as shown in Table 1. For each example, the flexural modulus, glass transition temperature, transparency, and weather resistance (color difference ΔE) of the cured resin product, as well as the weather resistance of the fiber-reinforced composite material, were all good, as shown in Table 1.

[0080] <Comparative Example 1> A cured resin and prepreg were prepared using the same method as in Example 1, using the composition shown in Table 2. The results of the physical property evaluation are also shown in Table 1 (the same applies to subsequent comparative examples). The transparency and weather resistance of the cured resin, as well as the weather resistance of the fiber-reinforced composite material, were good. However, the content of component [A] in 100 parts by mass of the total epoxy resin was less than 20 parts by mass, which did not satisfy condition (1). Therefore, the flexural modulus and glass transition temperature of the cured resin were lower than those in Example 5.

[0081] <Comparative Example 2> A cured resin and prepreg were prepared using the same method as in Example 1 using the compositions shown in Table 3. The cured resin exhibited good flexural modulus, glass transition temperature, and weather resistance, as well as good weather resistance of the fiber-reinforced composite material. However, the content of component [A] exceeded 50 parts by mass per 100 parts by mass of the total epoxy resin, failing to satisfy condition (1). Consequently, the cured resin exhibited poor transparency compared to Example 6.

[0082] <Comparative Example 3> A cured resin and prepreg were prepared using the same method as in Example 1 using the compositions shown in Table 4. The cured resin exhibited excellent flexural modulus, transparency, and weather resistance, and the fiber-reinforced composite material exhibited excellent weather resistance. However, the content of component [B] in 100 parts by mass of the total epoxy resin was less than 10 parts by mass, failing to satisfy condition (2). Consequently, the glass transition temperature was lower than that of Example 8.

[0083] <Comparative Example 4> A cured resin and prepreg were prepared using the same method as in Example 1 using the compositions shown in Table 2. The cured resin exhibited good glass transition temperature, transparency, and weather resistance, and the fiber-reinforced composite material exhibited good weather resistance. However, the content of component [B] exceeded 40 parts by mass per 100 parts by mass of the total epoxy resin, failing to satisfy condition (2). Consequently, the flexural modulus of the cured resin was lower than that of Example 5. <Comparative Example 5> A cured resin and prepreg were prepared using the same method as in Example 1 using the compositions shown in Table 2. The cured resin exhibited good glass transition temperature, transparency, and weather resistance, and the fiber-reinforced composite material exhibited good weather resistance. However, the content of component [C] in 100 parts by mass of the total epoxy resin was less than 10 parts by mass, failing to satisfy condition (3). Consequently, the flexural modulus was lower than that of Example 5.

[0084] <Comparative Example 6> A cured resin and prepreg were prepared using the same method as in Example 1 using the compositions shown in Table 4. The cured resin exhibited good flexural modulus, transparency, and weather resistance, and the fiber-reinforced composite material exhibited good weather resistance. However, the content of component [C] exceeded 40 parts by mass per 100 parts by mass of the total epoxy resin, failing to satisfy condition (3). Consequently, the cured resin exhibited a lower glass transition temperature than that of Example 8.

[0085] <Comparative Example 7> A cured resin and prepreg were prepared using the same method as in Example 1 using the composition shown in Table 3. The cured resin exhibited good flexural modulus, glass transition temperature, and weather resistance, as well as good weather resistance of the fiber-reinforced composite material. However, the total content of component [B] and component [C] in 100 parts by mass of the total epoxy resin was less than 40 parts by mass, failing to satisfy condition (4). Consequently, the cured resin exhibited poor transparency compared to Example 6.

[0086] <Comparative Example 8> A cured resin and a prepreg were prepared using the same method as in Example 1 using the compositions shown in Table 4. The cured resin exhibited good flexural modulus, transparency, and weather resistance, and the fiber-reinforced composite material exhibited good weather resistance. However, the content of component [C] exceeded 40 parts by mass per 100 parts by mass of the total epoxy resin, failing to satisfy condition (3), and the content of component [A] was less than 20 parts by mass, failing to satisfy condition (1). Consequently, the glass transition temperature of the cured resin was lower than that of Example 9.

[0087] Comparative Examples 9 and 10 Using the compositions shown in Table 5, a cured resin and prepreg were produced using the same method as in Example 1. The cured resin exhibited excellent glass transition temperature, transparency, and weather resistance, and the fiber-reinforced composite material exhibited excellent weather resistance. However, since component [C] was not incorporated, condition (3) was not satisfied, resulting in a lower flexural modulus than in all other examples.

[0088] <Comparative Example 11> Using the compositions shown in Table 5, a cured resin and prepreg were produced using the same method as in Example 1. The cured resin exhibited good flexural modulus, glass transition temperature, and weather resistance, as well as good weather resistance of the fiber-reinforced composite material. However, since component [C] was not incorporated, condition (3) was not satisfied, resulting in poor transparency compared to all other examples.

[0089] <Comparative Example 12> A cured resin and prepreg were prepared using the same method as in Example 1 using the compositions shown in Table 3. The cured resin exhibited good flexural modulus, glass transition temperature, and weather resistance, as well as good weather resistance of the fiber-reinforced composite material. However, since component [C] was not added and a pentaerythritol-based epoxy resin (an aliphatic epoxy resin without hydroxyl groups) was added, condition (3) was not satisfied, resulting in poor transparency compared to Example 6.

[0090] <Comparative Example 13> A cured resin product and a prepreg were prepared using the same method as in Example 1 using the compositions shown in Table 3. The cured resin product had good flexural modulus, glass transition temperature, and transparency. Since the content of component [E] exceeded 10 parts by mass in 100 parts by mass of the total epoxy resin, condition (5) was not satisfied. Therefore, the weather resistance of the cured resin product and the fiber-reinforced composite material was inferior to that of Example 6 or Example 10.

[0091] <Comparative Example 14> A cured resin and prepreg were prepared using the same method as in Example 1 using the compositions shown in Table 2. The cured resin exhibited excellent glass transition temperature, transparency, and weather resistance, and the fiber-reinforced composite material exhibited excellent weather resistance. However, due to the omission of component [D], the flexural modulus of the cured resin was lower than that of Example 5.

[0092] <Comparative Example 15> A cured resin and prepreg were prepared using the same method as in Example 1 using the composition shown in Table 3. The cured resin exhibited good flexural modulus, glass transition temperature, and weather resistance, as well as good weather resistance of the fiber-reinforced composite material. However, the total content of component [B] and component [C] in 100 parts by mass of the total epoxy resin was less than 40 parts by mass, failing to satisfy condition (4). Consequently, the cured resin exhibited poor transparency compared to Example 6.

[0093] [Table 1] [Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Ingredients[A] EPICLON N-775 35 45 35 35 45 35 35 EPICLON N-695 35 35 35 25 25 25 35 Ingredient [B] 「DER」858 25 25 25 35 35 25 25 15 40 25 25 35 25 25 Ingredient [C] Denacol EX-614B 20 15 15 15 20 35 35 35 20 20 15 20 Denacol EX-512 20 20 Ingredient [E] Araldite MY0600 5 Ingredients [H] EPICLON 830 20 20 25 15 25 10 5 15 5 20 25 20 20 Denacol EX-411 Ingredient [D] DICY7 5.8 5.5 5.5 5.1 5.2 5.7 5.8 6.1 5.0 5.9 5.8 6.8 5.8 5.5 Ingredients[F] 2-Pyrrolidone 3 1,2-Propanediol 3 Ingredient [G] Phenototo YP-70 3 3 3 3 3 3 3 3 3 3 3 3 3 Hardening accelerator DCMU99 3 3 3 3 3 3 3 3 3 3 3 3 3 3 Characteristics of cured resin Bending elastic modulus [GPa] 4.0 3.9 4.0 3.9 3.8 4.0 4.2 4.2 4.0 4.1 4.0 4.0 4.2 4.1 Glass transition temperature [℃] 140 138 141 143 134 142 135 130 131 146 141 138 131 130 transparency A A A A A B A A A B B A A A Weather resistance (ΔE) 6.7 7.2 7.3 7.0 6.8 8.2 6.5 6.5 6.2 9.3 7.5 7.0 6.5 6.9 Composite properties Weather resistance ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

[0094] [Table 2] [Table 2] Example 1 Example 5 Example 12 Comparative Example 1 Comparative Example 4 Comparative Example 5 Comparative Example 14 Ingredients[A] EPICLON N-775 35 EPICLON N-695 25 25 15 25 25 25 Ingredient [B] 「DER」858 25 35 35 35 45 35 35 Ingredient [C] Denacol EX-614B 20 15 15 15 15 5 15 Denacol EX-512 Ingredient [E] Araldite MY0600 Ingredients [H] EPICLON 830 20 25 25 35 15 35 25 Denacol EX-411 Ingredient [D] DICY7 5.8 5.2 6.8 5.4 4.8 5.2 Ingredients[F] 2-Pyrrolidone 1,2-Propanediol Ingredient [G] Phenototo YP-70 3 3 3 3 3 3 3 Hardening accelerator DCMU99 3 3 3 3 3 3 3 Characteristics of cured resin Bending elastic modulus [GPa] 4.0 3.8 4.0 3.6 3.6 3.6 3.3 Glass transition temperature [℃] 140 134 138 125 139 137 132 transparency A A A A A B A Weather resistance (ΔE) 6.7 6.8 7.0 6.4 7.3 8.3 6.6 Composite properties Weather resistance ○ ○ ○ ○ ○ ○ ○

[0095] [Table 3] [Table 3] Example 1 Example 6 Example 10 Comparative Example 2 Comparative Example 7 Comparative Example 12 Comparative Example 13 Comparative Example 15 Ingredients[A] EPICLON N-775 35 45 45 55 45 45 45 45 EPICLON N-695 Ingredient [B] 「DER」858 25 25 25 25 25 25 25 15 Ingredient [C] Denacol EX-614B 20 20 20 20 10 15 20 Denacol EX-512 Ingredient [E] Araldite MY0600 5 15 Ingredients [H] EPICLON 830 20 10 5 20 10 20 Denacol EX-411 20 Ingredient [D] DICY7 5.8 5.7 5.9 5.6 5.7 5.0 6.3 6.1 Ingredients[F] 2-Pyrrolidone 1,2-Propanediol Ingredient [G] Phenototo YP-70 3 3 3 3 3 3 3 3 Hardening accelerator DCMU99 3 3 3 3 3 3 3 3 Characteristics of cured resin Bending elastic modulus [GPa] 4.0 4.0 4.1 4.1 3.7 4.0 4.2 4.1 Glass transition temperature [℃] 140 142 146 147 144 136 157 134 transparency A B B C C C B C Weather resistance (ΔE) 6.7 8.2 9.3 9.1 9.1 8.5 11.3 9.3 Composite properties Weather resistance ○ ○ ○ ○ ○ ○ × ○

[0096] [Table 4] [Table 4] Example 1 Example 8 Example 9 Comparative Example 3 Comparative Example 6 Comparative Example 8 Ingredients[A] EPICLON N-775 35 35 35 35 EPICLON N-695 25 15 Ingredient [B] 「DER」858 25 15 40 5 15 40 Ingredient [C] Denacol EX-614B 20 35 35 35 45 45 Denacol EX-512 Ingredient [E] Araldite MY0600 Ingredients [H] EPICLON 830 20 15 25 5 Denacol EX-411 Ingredient [D] DICY7 5.8 6.1 5.0 6.5 6.1 5.3 Ingredients[F] 2-Pyrrolidone 1,2-Propanediol Ingredient [G] Phenototo YP-70 3 3 3 3 3 3 Hardening accelerator DCMU99 3 3 3 3 3 3 Characteristics of cured resin Bending elastic modulus [GPa] 4.0 4.2 4.0 4.3 4.3 4.0 Glass transition temperature [℃] 140 130 131 123 124 119 transparency A A A B A A Weather resistance (ΔE) 6.7 6.5 6.2 8.0 6.6 6.4 Composite properties Weather resistance ○ ○ ○ ○ ○ ○

[0097] [Table 5] [Table 5] Example 1 Comparative Example 9 Comparative Example 10 Comparative Example 11 Ingredients[A] EPICLON N-775 35 30 20 20 EPICLON N-695 Ingredient [B] 「DER」858 25 35 20 50 Ingredient [C] Denacol EX-614B 20 Denacol EX-512 Ingredient [E] Araldite MY0600 Ingredients [H] EPICLON 830 20 35 60 30 Denacol EX-411 Ingredient [D] DICY7 5.8 5.4 2.0 6.5 Ingredients[F] 2-Pyrrolidone 1,2-Propanediol Ingredient [G] Phenototo YP-70 3 3 3 3 Hardening accelerator DCMU99 3 3 3 3 Characteristics of cured resin Bending elastic modulus [GPa] 4.0 3.6 3.3 3.7 Glass transition temperature [℃] 140 145 130 147 transparency A B A C Weather resistance (ΔE) 6.7 8.6 6.8 8.4 Composite properties Weather resistance ○ ○ ○ ○

Claims

1. A prepreg comprising reinforcing fibers and a resin composition, wherein the resin composition comprises the following components [A] to [D] and satisfies the following conditions (1) to (5): Component [A]: phenolic varnish type epoxy resin component [B]: oxazolidinone type epoxy resin component [C]: any one or two of sorbitol type epoxy resin and glycerol type epoxy resin component [D]: dicyandiamine Condition (1): The content of component [A] is 20 to 50 parts by weight relative to 100 parts by weight of all epoxy resin; Condition (2): The content of component [B] is 10 to 40 parts by weight relative to 100 parts by weight of all epoxy resin; Condition (3): The content of component [C] is 10 to 40 parts by weight relative to 100 parts by weight of all epoxy resin; Condition (4): 100 parts by weight of all epoxy resin contains a total of 40 or more parts by weight of component [B] and component [C]. Condition (5): Does not contain component [E]: glycidylamine type epoxy resin, or if it is contained, it is less than 10 parts by weight relative to 100 parts by weight of all epoxy resin.

2. The prepreg as claimed in claim 1, which does not contain the component [E], or even if it does contain the component [E], it is less than 1 part by weight relative to 100 parts by weight of the total epoxy resin.

3. The prepreg as claimed in claim 1 further comprises component [F]: a compound having a boiling point of 130°C or higher and a molecular weight m of 50 or higher and 250 or lower, and having no epoxy groups in the molecule and no curing ability of epoxy resin.

4. The prepreg as claimed in claim 1, comprising component [G]: phenoxy resin as a thermoplastic resin.

5. A fiber-reinforced composite material obtained by hardening a prepreg as described in any one of claims 1 to 4.

6. A fiber-reinforced composite tubular body is obtained by molding a prepreg as described in any one of claims 1 to 4.

7. A golf club shaft made of a tubular body using a fiber-reinforced composite material as described in claim 6.

8. A fishing rod made of a tubular body using a fiber-reinforced composite material as described in claim 6.