Prepreg, fiber-reinforced composite, fiber-reinforced composite pipe, golf club shaft, fishing rod

Abstract

The present application provides a prepreg and a fiber-reinforced composite material, a fiber-reinforced composite material pipe, a golf club shaft, and a fishing rod using the same, which have excellent mechanical properties such as strength and elastic modulus, and excellent appearance such as low colorability, transparency, and weather resistance, and further have excellent tackiness, and the main object of the present application is a prepreg containing reinforcing fibers and a resin composition, the resin composition containing the following components [A] to [D] and satisfying the following conditions (1) to (3). Component [A]: an epoxy resin; component [B]: a dicyandiamide; component [C]: a compound having a boiling point of 130°C or higher and a molecular weight m of 50 or more and 250 or less, the compound having no epoxy group in the molecule and substantially no curing ability of the epoxy resin; component [D]: a phenoxy resin; (1): as component [A], 10 to 40 parts by mass of [A1] isocyanuric acid type epoxy resin is contained per 100 parts by mass of the total epoxy resin. (2): as component [A], 10 to 50 parts by mass of [A2] novolak type epoxy resin is contained per 100 parts by mass of the total epoxy resin. (3): as component [A], the content of [A3] glycidyl amine type epoxy resin is 10 parts by mass or less per 100 parts by mass of the total epoxy resin.

Description

Technical Field

[0001] This invention relates to a prepreg, a fiber-reinforced composite material, and a tubular body made of the fiber-reinforced composite material. The prepreg is suitable for use in aerospace, general industrial, and sports applications. Additionally, it relates to golf club shafts and fishing rods formed using the tubular body made from the fiber-reinforced composite material. Background Technology

[0002] Fiber-reinforced composites, using carbon fiber, aramid fiber, or similar reinforcing fibers, are widely used in structural materials for aircraft and automobiles, as well as in sports and general industrial applications such as tennis rackets, golf clubs, fishing rods, bicycles, and housings, due to their high specific strength and specific modulus of elasticity. As for the resin composition used in these fiber-reinforced composites, thermosetting resins are primarily used from the viewpoint of heat resistance and productivity; among these, epoxy resins are preferred from the viewpoint of mechanical properties such as adhesion to the reinforcing fibers.

[0003] In recent years, to apply fiber-reinforced composites to applications requiring further weight reduction, such as golf clubs, fishing rods, and bicycles, improvements in various physical properties have become increasingly necessary. For example, for prepregs used in tubular structures like golf clubs and fishing rods, excellent tackiness is required to prevent the prepregs from fraying during tubular formation. Furthermore, to exhibit excellent flexural strength within the tubular structure, the fiber-reinforced composites used require high fiber-direction and non-fiber-direction strengths, which are significantly influenced by the strength and elastic modulus of the epoxy resin used as the matrix resin. In addition, there is an increasing trend of using the cross-grid of reinforcing fibers in the surface design of fiber-reinforced composites through transparent coatings. Therefore, for epoxy resins used as the matrix resin, in addition to the excellent mechanical properties of the cured product, the appearance of the cured product, such as low colorfastness, transparency, and weather resistance, is also gaining increasing attention.

[0004] Therefore, to address the aforementioned issues, from the perspective of improving mechanical properties, Patent Document 1 investigated the following method: Additives are incorporated to reduce the possibility of dicyandiamide residue, used as a curing agent, becoming a defect, thereby improving resin strength. Furthermore, from the perspective of improving appearance, Patent Document 2 investigated the following method: The content of dicyandiamide, a major cause of damage to the appearance of molded articles, is reduced, and a cured product is obtained through bulk polymerization of epoxy resin.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2019 / 181402

[0008] Patent Document 2: International Publication No. 2018 / 003691 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] While the technology in Patent Document 1 improves resin strength, it does not address issues such as poor colorability and weather resistance, sometimes resulting in an unsatisfactory appearance. Furthermore, while the technology in Patent Document 2 produces resin-cured products and molded articles with excellent appearance, the cured resin exhibits low flexural strength and modulus of elasticity, sometimes exhibiting insufficient mechanical properties. Additionally, the technology in Patent Document 2 sometimes suffers from insufficient desired viscosity, leaving room for improvement in terms of operability.

[0011] Therefore, the objective of this invention is to provide a prepreg preform and fiber-reinforced composite materials using the prepreg preform, fiber-reinforced composite tubular bodies, golf club shafts, and fishing rods, wherein the prepreg preform exhibits excellent mechanical properties such as strength and modulus of elasticity, as well as excellent appearance such as low colorability, transparency, and weather resistance, and consequently, excellent tackiness.

[0012] Methods for solving problems

[0013] To solve the above-mentioned problems, the present invention employs the means described below. Specifically, the prepreg blank of the present invention is a prepreg blank comprising a reinforcing fiber and a resin composition.

[0014] The resin composition contains the following constituent elements [A] to [D] and satisfies the following conditions (1) to (3).

[0015] Constituent element [A]: Epoxy resin;

[0016] Component [B]: Dicyandiamide;

[0017] Constituent element [C]: A compound having a boiling point of 130°C or higher and a molecular weight m of 50 or higher and 250 or lower, wherein the compound does not have an epoxy group in the molecule and does not substantially have the curing ability of epoxy resin;

[0018] Constituent element [D]: Phenoxy resin;

[0019] (1): As a constituent element [A], it includes 10 to 40 parts by weight of [A1] isocyanuric acid type epoxy resin relative to 100 parts by weight of all epoxy resin.

[0020] (2): As a constituent element [A], it includes 10 to 50 parts by weight of [A2] phenolic varnish type epoxy resin relative to 100 parts by weight of all epoxy resin.

[0021] (3): As a constituent element [A], the content of glycidylamine type epoxy resin [A3] is less than 10 parts by mass relative to 100 parts by mass of all epoxy resin.

[0022] The fiber-reinforced composite material of the present invention is a fiber-reinforced composite material formed by curing the above-mentioned prepreg blank.

[0023] The fiber-reinforced composite tubular body of the present invention is obtained by molding the above-mentioned prepreg blank into a tubular shape.

[0024] The golf club shaft of the present invention is a golf club shaft formed using a tubular body made of the aforementioned fiber-reinforced composite material.

[0025] The fishing rod of the present invention is a fishing rod formed by using the above-mentioned fiber-reinforced composite material to make a tubular body.

[0026] Invention Effects

[0027] According to the present invention, a prepreg blank and fiber-reinforced composite materials using the prepreg blank, fiber-reinforced composite tubular bodies, golf club shafts, and fishing rods can be obtained, wherein the prepreg blank simultaneously achieves excellent mechanical properties and appearance, and further has excellent tackiness. Detailed Implementation

[0028] The present invention will now be described in detail.

[0029] The prepreg blank of the present invention comprises a resin composition and reinforcing fibers. Preferably, it is composed of a resin composition and reinforcing fibers. As the resin composition, an epoxy resin composition is used, comprising constituent elements [A] to [D] as essential components. It should be noted that, in the present invention, the term "constituent element" refers to the resin or compound contained in the resin composition.

[0030] In this invention, constituent element [A] is the epoxy resin contained in the resin composition. When constituent element [A] is an epoxy resin having two or more epoxy groups per molecule, the glass transition temperature of the cured product obtained by heating and curing the resin composition is higher, and the heat resistance is also higher, which is therefore preferred. Epoxy resin having one epoxy group per molecule may also be used, provided it does not significantly adversely affect the heat resistance or mechanical properties of the epoxy resin composition or the fiber-reinforced composite material.

[0031] Examples of epoxy resins mentioned above include bisphenol type, isocyanuric acid type, phenolic varnish type, cresol varnish type, dicyclopentadiene type, diaminodiphenylmethane type, diaminodiphenyl sulfone type, aminophenol type, m-xylenediamine type, 1,3-diaminomethylcyclohexane type, hydantoin type, sorbitol type, trihydroxyphenylmethane type, and tetrahydroxyphenylethane type.

[0032] In this invention, in order to satisfy condition (1), it is necessary to include [A1] isocyanuric acid type epoxy resin (hereinafter, sometimes simply referred to as [A1]) as constituent element [A]. By including [A1], the flexural modulus of the cured resin is increased, the coloring of the cured resin is reduced or the weather resistance is improved, and a fiber-reinforced composite material with excellent mechanical properties and appearance can be obtained.

[0033] The resin composition must contain 10 to 40 parts by weight of [Al] relative to all 100 parts by weight of epoxy resin. The lower limit is preferably 15 parts by weight or more, and the upper limit is preferably 30 parts by weight or less. By including [Al] within this range, the cured resin exhibits less coloring and turbidity, and a better balance between elastic modulus and appearance (hue, transparency).

[0034] As a commercially available product under [A1], it can use "TEPIC (registered trademark)" -G, -S, -L, -VL, -PAS B22 (all manufactured by Nissan Chemical Industries, Ltd.) and "Araldite (registered trademark)" PT9810 (manufactured by Hantsman Advanston Materias Co., Ltd.).

[0035] Furthermore, in order to satisfy condition (2) in this invention, it is necessary to include [A2] phenolic varnish-type epoxy resin (hereinafter, sometimes simply referred to as [A2]) as constituent element [A]. By including [A2], the color of the resin cured product is reduced, the tackiness of the prepreg blank is improved, and a prepreg blank with excellent tackiness and a fiber-reinforced composite material with excellent appearance can be obtained.

[0036] The resin composition must contain 10 to 50 parts by weight of [A2] relative to all 100 parts by weight of epoxy resin. The lower limit is preferably 15 parts by weight or more, and the upper limit is preferably 40 parts by weight or less. By including [A2] within this range, the cured resin exhibits less coloring and turbidity, and the prepreg blank shows better balance in terms of tackiness and appearance (hue, transparency).

[0037] Examples of [A2] include phenolic varnish-type epoxy resins and cresol varnish-type epoxy resins. Among these, considering the good balance of physical properties such as tackiness when preparing prepreg blanks, epoxy resins with a softening point of 60–110°C are preferred, and epoxy resins with a softening point of 70–100°C are even more preferred.

[0038] Commercially available phenolic varnish-type epoxy resins include "jER (registered trademark)" 152 and 154 (manufactured by Mitsubishi Kemikal Co., Ltd.), EPPN-201 (manufactured by Nippon Kayaku Co., Ltd.), and "EPICLON (registered trademark)" N-740, N-770 (softening point: 65-75℃), N-775 (softening point: 70-80℃, manufactured by DIC Co., Ltd.).

[0039] Commercially available products of cresol-phenolic varnish-type epoxy resins include "EPICLON (registered trademark)" N-660 (softening point: 62~70℃), N-665 (softening point: 65~74℃), N-670 (softening point: 69~77℃), N-673 (softening point: 73~82℃), N-680 (softening point: 82~92℃), N-690 (softening point: 88~98℃), and N-695 (softening point: 90~100℃, all manufactured by DIC Corporation).

[0040] In this invention, in order to satisfy condition (3), as a constituent element [A], the content of glycidylamine type epoxy resin (hereinafter, sometimes simply referred to as [A3]) must be 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably substantially non-containing [A3], relative to 100 parts by mass of all epoxy resin. Glycidylamine type epoxy resin refers to an epoxy resin having glycidyl amino groups. By making the content of [A3] 10 parts by mass or less, the cured resin exhibits less coloring and improved weather resistance, resulting in a fiber-reinforced composite material with excellent appearance (color tone, weather resistance). Here, "substantially non-containing [A3]" means that the content of [A3] is less than 1 part by mass relative to 100 parts by mass of all epoxy resin (including the case where the content of [A3] is zero).

[0041] Examples of [A3] include diaminodiphenylmethane type epoxy resin, diaminodiphenylsulfone type epoxy resin, aminophenol type epoxy resin, m-xylenediamine type epoxy resin, and 1,3-diaminomethylcyclohexane type epoxy resin.

[0042] Examples of commercially available diaminodiphenylmethane-type epoxy resins include ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), "Araldos (registered trademark)" MY720, MY721, MY9512, and MY9663 (the above are "Araldos"). Manufactured by ン·アドバンスト·マテリアルズ Co., Ltd.), "エポトート (registered trademark)" YH-434 (Nippon Steel Corporation Co., Ltd.), "jER (registered trademark)" 604 (manufactured by Mitsubishi Co., Ltd.), etc.

[0043] Commercially available products of diaminodiphenyl sulfone type epoxy resins include TG3DAS (manufactured by Mitsui Chemicals Fine Co., Ltd.).

[0044] Commercially available aminophenol-type epoxy resins include ELM120, ELM100 (all manufactured by Sumitomo Chemical Co., Ltd.), "jER" 630 (manufactured by Mitsubishi Kemikal Co., Ltd.), and "Araldite" MY0500, MY0510, MY0600, and MY0610 (manufactured by Hantsman Advansto Matteralz Co., Ltd.).

[0045] As a commercially available product of m-xylene diamine type epoxy resin, "TETRAD (registered trademark)"-X (manufactured by Mitsubishi Gas Chemical Co., Ltd.) can be cited.

[0046] As a commercially available product of 1,3-diaminomethylcyclohexane type epoxy resin, “TETRAD (registered trademark)”-C (manufactured by Mitsubishi Gas Chemical Co., Ltd.) can be cited.

[0047] Regarding component [A], it is preferable to include [A4] bisphenol-type epoxy resin (hereinafter, sometimes simply referred to as [A4]). By including [A4], the viscosity of the resin composition can be adjusted without impairing the color, transparency, and weather resistance of the cured resin. Therefore, the viscosity of the prepreg blank can be improved, and a prepreg blank with excellent workability can be produced. From the above aspects, it is preferable to include [A4].

[0048] Examples of [A4] include bisphenol A type epoxy resin and bisphenol F type epoxy resin. The composition preferably contains 10 to 60 parts by weight of [A4] relative to 100 parts by weight of all epoxy resin contained in the resin composition; more preferably, it contains 15 parts by weight or more at the lower limit; and more preferably, it contains 50 parts by weight or less at the upper limit.

[0049] Commercially available bisphenol A type epoxy resins include "jER (registered trademark)" 825, 828, 834, 1001, 1002, 1003, 1003F, 1004, 1004AF, 1005F, 1006FS, 1007, 1009, 1010 (all manufactured by Mitsubishi Kemica Co., Ltd.), "EPICLON (registered trademark)" 850 (manufactured by DIC Co., Ltd.), "Epotet (registered trademark)" YD-128 (manufactured by Nippon Steel Kemica & Materia Co., Ltd.), and DER-331, 332 (manufactured by Dow Kemica Co., Ltd.).

[0050] Commercially available bisphenol F type epoxy resins include "AralDite" GY282 (manufactured by Hantsman Advansto Materia Medica Co., Ltd.), "jER" 806, 807, 4005P, 4007P, 4010P (manufactured by Mitsubishi Kemikal Co., Ltd.), "EPICLON" 830 (manufactured by DIC Co., Ltd.), and "Epotet" YD-170 (manufactured by Nippon Steel Kemikal & Materia Medica Co., Ltd.).

[0051] Furthermore, regarding component [A], it is preferred that the total amount of [A1] isocyanuric acid type epoxy resin, [A2] phenolic varnish type epoxy resin, and [A4] bisphenol type epoxy resin accounts for at least 96% by mass, more preferably at least 99% by mass, and even more preferably 100% by mass of the total epoxy resin. This results in excellent mechanical properties (strength, modulus of elasticity) and appearance (hue, transparency, weather resistance) of the cured resin, as well as excellent tackiness of the prepreg blank. Additionally, in this invention, component [A] may include epoxy resins other than those described above ([A1] to [A4]), and when the amount of the total epoxy resin is set to 100% by mass, it is preferably less than 4% by mass.

[0052] In this invention, component [B] is dicyandiamide contained in the resin composition. Dicyandiamide excels in imparting high mechanical properties and heat resistance to cured epoxy resins and is widely used as a curing agent for various epoxy resins. Furthermore, epoxy resin compositions exhibit excellent storage stability, making it suitable for use. Commercially available dicyandiamides include DICY7 and DICY15 (manufactured by Mitsubishi Kemikal Co., Ltd.).

[0053] Furthermore, in this invention, considering the excellent balance between the mechanical properties and transparency of the cured resin, the content of constituent element [B] is preferably 4 to 9 parts by mass relative to 100 parts by mass of the total epoxy resin, and more preferably 5 to 7 parts by mass.

[0054] The constituent element [C] in this invention is a compound contained in the resin composition that has a boiling point of 130°C or higher and a molecular weight m of 50 or higher and 250 or lower. This compound does not have an epoxy group in its molecule and substantially does not possess the curing ability of epoxy resin. Here, compounds such as amines and phenols that can undergo addition reactions with epoxy resin, acid anhydrides that can copolymerize with epoxy resin, imidazoles that can act as initiators for the bulk polymerization of epoxy resin, aromatic urea compounds, and tertiary amine compounds are compounds that possess the curing ability of epoxy resin. Furthermore, the phrase "substantially does not possess the curing ability of epoxy resin" means that it does not chemically react with epoxy resin and does not participate in the bulk polymerization of epoxy resin.

[0055] It is believed that component [C] is not introduced into the cross-linking structure formed by the reaction of epoxy resin and dicyandiamide, but exists in its voids, i.e., it is encapsulated in the cross-linking structure. Even after the epoxy resin is cured, there are no chemical or physical changes, and it maintains the state before the epoxy resin was cured. Therefore, it is believed that the elastic modulus of the resulting cured epoxy resin is higher. In addition, surprisingly, by incorporating component [C], an epoxy resin cured product with not only high elastic modulus, but also high elongation and high strength can be obtained.

[0056] Furthermore, since the boiling point of constituent element [C] is 130°C or higher, more preferably 180°C or higher, the volatilization of constituent element [C] during the curing of the epoxy resin composition can be suppressed, resulting in a resin-cured product and fiber-reinforced composite material with excellent mechanical properties. Additionally, by setting the boiling point of constituent element [C] to the above-mentioned range, the generation of voids and the reduction of mechanical properties in the obtained fiber-reinforced composite material can be suppressed, which is therefore preferred. Furthermore, while there is no particular upper limit to the boiling point of constituent element [C], the boiling point of the compounds commonly used in this invention is suitable to be below 400°C.

[0057] Relative to 100 parts by mass of constituent element [A], it is preferable to include 1 to 15 parts by mass of constituent element [C], more preferably 2 to 10 parts by mass of constituent element [C], and even more preferably 3 to 6 parts by mass of constituent element [C].

[0058] The molecular weight m of the constituent element [C] is 50 or more and 250 or less, more preferably 70 or more and 120 or less. By making the molecular weight of the constituent element [C] within the above range, the constituent element [C] is appropriately retained in the voids of the cross-linked structure formed by the reaction of epoxy resin and dicyandiamide, and a cured product with excellent elastic modulus, strength and elongation can be obtained.

[0059] In this invention, the constituent element [C] is preferably a compound having at least one functional group selected from amide, ketone, and hydroxyl groups within its molecule. When the constituent element [C] has highly polar functional groups as described above within its molecule, strong intermolecular interactions occur between the hydroxyl groups in the crosslinked structure formed by the constituent elements [A] and [B] and the constituent element [C]. The constituent element [C] is easily and appropriately retained in the voids of the crosslinked structure, thus achieving particularly excellent effects in improving elongation and strength.

[0060] Examples of the aforementioned constituent element [C] include amides such as N-methylformamide, N-methylacetamide, 2-pyrrolidone, N-methylpropionamide, N-ethylacetamide, N-methylacetanilide, and N,N'-diphenylacetamide, as well as diols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, and heptaethylenediol. These compounds can be used alone or in combination as appropriate.

[0061] In this invention, component [D] is phenoxy resin contained in the resin composition. Phenoxy resin can improve the viscosity of the resin composition and the tackiness of the prepreg without impairing the color, transparency, and weather resistance of the cured resin. Therefore, by including component [D], a prepreg with excellent tackiness and a fiber-reinforced composite material with excellent appearance can be obtained. It is preferable to include 3 to 20 parts by weight of component [D] relative to 100 parts by weight of component [A], and more preferably 5 to 15 parts by weight of component [D].

[0062] In the resin composition used in the prepreg blank of the present invention, a curing accelerator can be incorporated from the viewpoint of controlling the curing speed. Examples of curing accelerators include urea compounds and imidazole compounds, and urea compounds are particularly preferred from the viewpoint of the storage stability of the epoxy resin composition.

[0063] Examples of urea compounds include 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, phenyl dimethylurea, and toluene dimethylurea. Additionally, commercially available aromatic urea compounds include DCMU99 (manufactured by Hodo-Gaya Chemical Industry Co., Ltd.) and "Omicure" 24 (manufactured by Pitti Iai Japan Co., Ltd.).

[0064] Examples of reinforcing fibers used in the prepreg and fiber-reinforced composite materials of the present invention include carbon fiber, graphite fiber, aramid fiber, and glass fiber, but carbon fiber is particularly preferred. The morphology and arrangement of the reinforcing fibers are not limited, and fiber structures such as unidirectional dovetailed long fibers, single tows, woven fabrics, knitted fabrics, and braided fabrics can be used. Two or more types of reinforcing fibers, such as carbon fiber, glass fiber, aramid fiber, boron fiber, and polystyrene fiber, can also be used in combination. Zyrazole fiber, high-strength polyethylene fiber, alumina fiber, and silicon carbide fiber, etc.

[0065] Specifically, carbon fibers include acrylonitrile-based, pitch-based, and rayon-based fibers, with acrylonitrile-based carbon fibers, which have high tensile strength, being particularly preferred.

[0066] As a form of carbon fiber, twisted yarn, untwisted yarn, and untwisted yarn can be used. However, in the case of twisted yarn, the orientation of the long filaments constituting the carbon fiber is not parallel, which is the reason for the reduction of the mechanical properties of the resulting carbon fiber reinforced composite material. Therefore, it is preferable to use untwisted yarn or untwisted yarn, which have a good balance between the formability and strength properties of carbon fiber reinforced composite materials.

[0067] The tensile modulus of elasticity of carbon fiber is preferably in the range of 200–440 GPa. The tensile modulus of elasticity of carbon fiber is affected by the crystallinity of the graphite structure constituting the carbon fiber; the higher the crystallinity, the higher the modulus of elasticity. If the tensile modulus of elasticity of carbon fiber is within this range, the rigidity and strength of the carbon fiber reinforced composite material are both high and balanced, and therefore it is preferred. A more preferred modulus of elasticity is in the range of 230–400 GPa, and even more preferred is in the range of 260–370 GPa. Here, the tensile modulus of elasticity of carbon fiber is a value measured according to JIS R7601 (2006).

[0068] The prepreg blanks of the present invention can be manufactured using various known methods. For example, the prepreg blanks can be manufactured using a hot-melt method, which reduces the viscosity of the resin composition by heating without using organic solvents, thereby impregnating it in the reinforcing fibers.

[0069] In the hot melt method, the following methods can be used: a method in which a resin composition that has been reduced in viscosity by heating is directly impregnated into the reinforcing fiber; or, a method in which a release paper sheet with a resin film is first made by temporarily coating the resin composition onto the release paper or the like, and then the resin film is overlapped on the reinforcing fiber side from both sides or one side, and then heated and pressurized to impregnate the resin composition into the reinforcing fiber, etc.

[0070] When the mass of the prepreg preform is set to 100% by mass, the content of reinforcing fibers in the prepreg preform is preferably 30-90% by mass, more preferably 35-85% by mass, and even more preferably 65-85% by mass. If the content of reinforcing fibers is low, the amount of resin is too high, making it difficult to obtain the advantages of fiber-reinforced composites with excellent specific strength and specific modulus of elasticity. In addition, during the molding of fiber-reinforced composites, there is a possibility that the heat generated during curing becomes too high. On the other hand, if the content of reinforcing fibers is too high, poor resin impregnation will occur, raising concerns that the resulting composite material will be a material with many voids. Furthermore, there is a concern that the tackiness of the prepreg preform may be compromised.

[0071] The fiber-reinforced composite material or tubular body made of fiber-reinforced composite material of the present invention can be manufactured by, as an example, the following method: the prepreg blank of the present invention is laminated in a prescribed shape and subjected to pressure / heat to cure the resin. Here, as a method of applying heat and pressure, pressure molding, autoclave molding, bag molding, wrapping tape, internal pressure molding, etc., can be used.

[0072] In the molding method of fiber-reinforced composite tubular bodies, the tape winding method is particularly preferred. The tape winding method involves winding a prepreg blank onto a mandrel or similar core to obtain a cylindrical molded body. Specifically, a prepreg blank is wound and attached to a mandrel, and a tape made of thermoplastic resin film is wound and attached to its outer periphery for fixing the prepreg blank and applying pressure. After the resin is heated and cured in an oven, the mandrel is removed to obtain a cylindrical molded body. This method is suitable for manufacturing rod-shaped bodies such as golf club shafts and fishing rods.

[0073] The fiber-reinforced composite tubular body of the present invention is obtained by molding the aforementioned prepreg preform with excellent tackiness. Therefore, the winding spalling during tubular formation is reduced, resulting in a tubular body with fewer defects such as voids. Furthermore, if the prepreg preform of the present invention is used, its cured product has excellent mechanical properties. Therefore, the fiber-reinforced composite tubular body of the present invention exhibits excellent flexural strength.

[0074] The fiber-reinforced composite material or tubular body made of fiber-reinforced composite material of the present invention can be widely used in aerospace, general industrial, and sports applications. More specifically, in general industrial applications, it is suitable for structures in automobiles, ships, and railway vehicles. In sports applications, it is suitable for use in golf clubs, fishing rods, tennis rackets, and badminton rackets. The tubular body made of fiber-reinforced composite material of the present invention is suitable for use in golf club shafts and fishing rods.

[0075] Unless otherwise specified, the upper and lower limits of the numerical ranges recorded above can be combined arbitrarily.

[0076] Example

[0077] The present invention will now be described in detail with reference to the embodiments. However, it should not be construed as limiting the present invention to these embodiments. It should be noted that, unless otherwise specified, the unit "parts" of composition ratio refers to parts by mass. In addition, unless otherwise specified, the determination of various properties (physical properties) is carried out at an environment of 23°C and 50% relative humidity.

[0078] <Materials used in the examples and comparative examples>

[0079] (1) Constituent element [A]: Epoxy resin

[0080] ·[A1] Isocyanuric acid type epoxy resin

[0081] [A1]-1 "TEPIC (registered trademark)"-S (Epoxy equivalent: 100, manufactured by Nissan Chemical Industries, Ltd.)

[0082] ·[A2] Phenolic varnish type epoxy resin

[0083] [A2]-1 "EPICLON (registered trademark)" N-775 (Phenolic varnish-type epoxy resin, epoxy equivalent: 189, manufactured by DIC Co., Ltd.)

[0084] [A2]-2 "EPICLON (registered trademark)" N-695 (Cresol-formaldehyde varnish type epoxy resin, epoxy equivalent: 214, manufactured by DIC Co., Ltd.)

[0085] • [A3] Glycidylamine type epoxy resin

[0086] [A3]-1 "Araloid (registered trademark)" MY0600 (aminophenol type epoxy resin, epoxy equivalent: 118, manufactured by Horton Chemical Co., Ltd.)

[0087] [A3]-2 "Sumitomo Chemical Co., Ltd." ELM434 (Diaminodiphenylmethane type epoxy resin, epoxy equivalent: 120, manufactured by Sumitomo Chemical Co., Ltd.)

[0088] ·[A4] Bisphenol type epoxy resin

[0089] [A4]-1 "EPICLON (registered trademark)" 830 (Bisphenol F type epoxy resin, epoxy equivalent: 172, manufactured by DIC Co., Ltd.)

[0090] [A4]-2 "jER (registered trademark)" 4005P (Bisphenol F type epoxy resin, epoxy equivalent: 1075, manufactured by Mitsubishi Kemica Co., Ltd.)

[0091] (2) Constituent element [B]: Dicyandiamide

[0092] [B]-1DICY7 (dicyandiamide, manufactured by Mitsubishi Microwave Co., Ltd.)

[0093] (3) Constituent element [C]: A compound with a boiling point of 130°C or higher and a molecular weight m of 50 or higher and 250 or lower, wherein the compound does not have epoxy groups in its molecule and does not substantially have the curing ability of epoxy resin.

[0094] [C]-11,2-Propanediol (boiling point: 188℃, molecular weight m: 76, manufactured by Tokyo Chemical Industry Co., Ltd.)

[0095] [C]-22-pyrrolidone (boiling point: 245℃, molecular weight m: 85, manufactured by Tokyo Chemical Industry Co., Ltd.)

[0096] (4) Constituent element [D]: Phenoxy resin

[0097] [D]-1 "Florence (Registered Trademark)" YP-70 (manufactured by Nippon Steel Corporation & Maritime Co., Ltd.)

[0098] (5) Other thermoplastic resins (the following are constituent elements [E])

[0099] [E]-1 "Vinyl Rec (registered trademark)"K (Polyvinyl formaldehyde, manufactured by JNK Corporation)

[0100] [E]-2 "Smica Eccell (Registered Trademark)" PES 5003P (Polyethersulfone, manufactured by Sumitomo Chemical Co., Ltd.)

[0101] (6) Curing accelerator (the following are constituent elements [F])

[0102] [F]-1DCMU99(3-(3,4-dichlorophenyl)-1,1-dimethylurea, manufactured by Hodokoya Chemical Industry Co., Ltd.)

[0103] (7) Carbon fiber

[0104] • "Treka (registered trademark)" T1100G-24K (24,000 fibers, tensile modulus of elasticity: 324 GPa, manufactured by Toreka Co., Ltd.)

[0105] <Preparation Method of Epoxy Resin Composition>

[0106] (1) Preparation of curing agent masterbatch

[0107] [A4]-1 was prepared in an amount of 10 parts by mass relative to 100 parts by mass of epoxy resin. The amount of component [B]: dicyandiamide shown in the table was added to it, and the mixture was kneaded at room temperature. The mixture was then passed through a three-roll mill twice to prepare a curing agent masterbatch.

[0108] (2) Preparation of epoxy resin composition

[0109] Add 90 parts by mass of the total amount of epoxy resin (excluding the amount of [A4]-1 used in (1)) shown in the table, i.e., when the total amount of epoxy resin is set to 100 parts by mass, to a beaker. While mixing, heat to 150°C, add component [D] or component [E] shown in the table, and heat and mix at 150°C for 1 hour to dissolve it. Then, while continuing to mix, cool down to 55-65°C, add the curing agent masterbatch prepared in (1) and component [C] and component [F] shown in the table, and mix at the same temperature for 30 minutes to obtain the epoxy resin composition.

[0110] <Preparation Method of Epoxy Resin Cured Products>

[0111] After degassing the epoxy resin composition prepared according to the above <Preparation Method of Epoxy Resin Composition> in a vacuum, the composition is placed in a mold with a thickness of 2 mm using a 2 mm thick "Teflon (registered trademark)" spacer. The temperature is increased from 30°C at a rate of 1.7°C / min to 90°C and held for 1 hour. Then, the temperature is increased at a rate of 2.0°C / min to 135°C and cured for 2 hours to obtain a 2 mm thick plate-shaped cured resin product.

[0112] In addition, for appearance evaluation, the above-mentioned curing reaction was carried out in a mold with a thickness of 1 mm using a 1 mm thick "Teflon (registered trademark)" spacer, to obtain a plate-shaped cured resin with a thickness of 1 mm.

[0113] <Prepreg Fabrication Method>

[0114] Using a doctor blade coater, the epoxy resin composition prepared according to the above-described <Preparation Method of Epoxy Resin Composition> is coated onto release paper to produce two sheets with a resin unit area weight of 31 g / m². 2 The resin film. Next, the fiber unit area weight is 125g / m². 2 The resin film is superimposed on both sides of the unidirectionally arranged carbon fibers in sheet form, and heated and pressurized at a temperature of 110°C and a maximum pressure of 2MPa to impregnate them with an epoxy resin composition, thereby obtaining a prepreg blank.

[0115] <Various Evaluation Methods>

[0116] (1) Three-point bending test of epoxy resin cured product

[0117] Cut test pieces with a width of 10 mm and a length of 60 mm from a 2 mm thick resin cured product prepared according to the above-mentioned <Preparation Method of Epoxy Resin Cured Product>. Use an Instron universal testing machine (manufactured by Instron Co., Ltd.) with a spacing of 32 mm, a crosshead speed of 2.5 mm / min, and a sample number of n=6. Perform 3-point bending according to JIS K7171 (1994). The arithmetic mean of the strength and elastic modulus at this time is taken as the bending strength and bending elastic modulus of the resin cured product, respectively.

[0118] (2) Evaluation of yellowness of epoxy resin cured products

[0119] A test piece with a width of 37 mm and a length of 68 mm was cut from a 1 mm thick cured resin material prepared according to the above-described <Method for Preparing Cured Epoxy Resin>. For this test piece, the tristimulus values ​​were determined using a multi-source spectrophotometer MSC-P (manufactured by Suga Testing Instruments Co., Ltd.) via a reflection method under optical conditions of a D65 light source, a 10° field of view, and d / 8 excluding positively reflected light. Based on the obtained tristimulus values, the yellowness was calculated according to JIS K7373 (2006).

[0120] (3) Evaluation of the transparency of epoxy resin cured products

[0121] A 1mm thick resin-cured product, prepared according to the above-described <Preparation Method for Epoxy Resin Cured Product>, was placed on paper with writing on it, and the transparency of the resin-cured product was checked. Cases where the writing was as clearly readable as before the resin-cured product was placed were recorded as A; cases where the writing was blurry but still readable were recorded as B; and cases where the writing was not readable were recorded as C.

[0122] (4) Weather resistance test of epoxy resin cured products

[0123] Test pieces with a width of 37 mm and a length of 68 mm were cut from a 1 mm thick cured resin product prepared according to the above-described <Method for Preparing Cured Epoxy Resin>. The following weathering resistance test was performed on the test pieces: accelerated weathering test (SuperXenon WeatherMeter SX-75, manufactured by Suga Testing Equipment Co., Ltd.) was conducted at a strength of 180 W / m². 2 The black panel was subjected to 102 minutes of waterless spraying under conditions of 63°C and 50% RH, and at an intensity of 180 W / m. 2 Irradiation for 18 minutes simultaneously with water spraying under the conditions of 28℃ and 99%RH in the tank is considered as one cycle, and it is repeated 12 times (i.e., 24 hours).

[0124] The weather resistance was evaluated as follows: The color difference (ΔE) of the cured product before and after the weather resistance test was measured using a multi-light source spectrophotometer MSC-P (manufactured by Suga Testing Equipment Co., Ltd.). The tristimulus values ​​(L) were determined under the same conditions as the yellowness evaluation of the epoxy resin cured product described in (2) above. ＊ a ＊ b ＊ The difference in tristimulus values ​​before and after the weathering test (ΔL) ＊ , Δa ＊ , Δb ＊ The color difference (ΔE) is calculated using the following formula (I).

[0125] ΔE={(ΔL ＊ ) 2 +(Δa ＊ ) 2 +(Δb ＊ ) 2} 1 / 2 ···(I)

[0126] (5) Determination of the tackiness of prepreg blanks

[0127] The tackiness of the prepreg blank was determined using a tack tester (PICMA Tack Tester II, manufactured by Toyo Seiki Co., Ltd.). An 18mm × 18mm square cover glass was pressed onto the prepreg blank with a force of 0.4 kgf (3.9 N) for 5 seconds, and then stretched vertically at a speed of 30 mm / min. The resistance to peeling off the cover glass was taken as the tackiness value.

[0128] <Example 1>

[0129] Using the following components [A]: 25 parts by weight of "TEPIC (registered trademark)"-S as component [A1], 35 parts by weight of "EPICLON (registered trademark)" N-77535 as component [A2], 25 parts by weight of "EPICLON (registered trademark)" 83025 as component [A4], 15 parts by weight of "jER (registered trademark)" 4005P as component [B], 75.4 parts by weight of dicyandiamide DICY as component [B], 5 parts by weight of 1,2-propanediol as component [C], 12 parts by weight of phenoxy resin "Fenotot (registered trademark)" YP-7012 as component [D], and 993 parts by weight of DCMU993 as a curing accelerator, an epoxy resin composition was prepared according to the above <Preparation Method of Epoxy Resin Composition>.

[0130] The obtained resin composition was used to prepare an epoxy resin cured product according to the <Preparation Method of Epoxy Resin Cured Product>. The flexural strength, flexural modulus, yellowness, transparency, and weather resistance (color difference ΔE) of the epoxy resin cured product were measured. The results showed that the flexural strength was 193 MPa, the flexural modulus was 4.7 GPa, the yellowness was 12, the transparency was A, and the ΔE was 6.8. The physical properties and appearance of the cured resin product were good.

[0131] In addition, a prepreg was prepared from the obtained resin composition according to the <Prepreg Preparation Method>, and the tackiness of the prepreg was measured. The results showed that the tackiness of the prepreg was 1.7 kgf, which showed excellent tackiness.

[0132] <Examples 2-12>

[0133] The resin composition was changed as shown in Table 1, except that the epoxy resin cured product and prepreg blank were prepared by the same method as in Example 1. Regarding each embodiment, the flexural strength, flexural modulus, yellowness, transparency, weather resistance (color difference ΔE), and tackiness of the prepreg blank were all good, as described in Table 1.

[0134] <Comparative Example 1>

[0135] As shown in Table 1, the resin composition was changed, except that the epoxy resin cured product and prepreg blank were prepared by the same method as in Example 1. The results of the physical property evaluation are also shown in Table 1 (as in the subsequent comparative examples). The yellowness, transparency, weather resistance, and tackiness of the epoxy resin cured product were good. However, the content of [Al] in 100 parts by weight of the total epoxy resin was less than 10 parts by weight, which did not meet condition (1). Therefore, the flexural strength and flexural modulus of the epoxy resin cured product were lower than those of Example 7.

[0136] <Comparative Example 2>

[0137] The resin composition was changed as shown in Table 1. Otherwise, the epoxy resin cured product and prepreg were prepared using the same method as in Example 1. The epoxy resin cured product exhibited good flexural modulus, yellowness, weather resistance, and prepreg adhesion. However, the [Al] content exceeded 40 parts by weight per 100 parts by weight of the total epoxy resin, failing to meet condition (1). Therefore, the flexural strength and transparency of the epoxy resin cured product were inferior to those of Example 6.

[0138] <Comparative Example 3>

[0139] The resin composition was changed as shown in Table 1. Otherwise, the epoxy resin cured product and prepreg blank were prepared by the same method as in Example 1. The epoxy resin cured product had good flexural modulus, yellowness, transparency, and weather resistance. However, the content of [A2] in 100 parts by weight of the total epoxy resin was less than 10 parts by weight, which did not meet condition (2). Therefore, the flexural strength and the viscosity of the prepreg blank were lower than those in Example 7.

[0140] <Comparative Example 4>

[0141] The resin composition was changed as shown in Table 1. Otherwise, the epoxy resin cured product and prepreg were prepared by the same method as in Example 1. The epoxy resin cured product had good flexural modulus, yellowness, weather resistance, and prepreg adhesion. However, the content of [A2] in 100 parts by weight of the total epoxy resin exceeded 50 parts by weight, which did not meet condition (2). Therefore, the flexural strength and transparency of the epoxy resin cured product were inferior to those in Example 4.

[0142] <Comparative Example 5>

[0143] The resin composition was changed as shown in Table 1. Otherwise, the epoxy resin cured product and prepreg were prepared using the same method as in Example 1. The epoxy resin cured product exhibited good yellowness, transparency, weather resistance, and the prepreg exhibited good tackiness. However, due to the absence of compounding element [B], the flexural strength and flexural modulus of the epoxy resin cured product were lower than those of Examples 5 and 9.

[0144] <Comparative Example 6>

[0145] The resin composition was changed as shown in Table 1, except that the epoxy resin cured product and prepreg were prepared by the same method as in Example 1. The epoxy resin cured product had good yellowness, transparency, weather resistance, and the prepreg exhibited good tackiness. However, due to the absence of compounding element [C], the flexural strength and flexural modulus of the epoxy resin cured product were lower than those of Example 5.

[0146] <Comparative Example 7>

[0147] As shown in Table 1, the resin composition was changed, except that the epoxy resin cured product and prepreg were prepared using the same method as in Example 1. The epoxy resin cured product exhibited good flexural strength, flexural modulus, and prepreg adhesion. However, since component [D] was not used, and "Vinylek (registered trademark)" K was used instead of thermoplastic resin, the yellowness, transparency, and weather resistance of the cured resin were inferior to those of Example 1.

[0148] <Comparative Example 8>

[0149] As shown in Table 1, the resin composition was changed, except that the epoxy resin cured product and prepreg were prepared by the same method as in Example 1. The epoxy resin cured product had good flexural strength, flexural modulus, transparency, and the prepreg exhibited good adhesion. However, the content of [A3] in 100 parts by weight of the total epoxy resin exceeded 10 parts by weight, failing to meet condition (3). Therefore, the yellowness and weather resistance of the resin cured product were inferior to those in Examples 1 and 8.

[0150] <Comparative Example 9>

[0151] As shown in Table 1, the resin composition was changed, except that the epoxy resin cured product and prepreg were prepared by the same method as in Example 1. The epoxy resin cured product had good flexural strength, flexural modulus, transparency, and the prepreg exhibited good adhesion. However, the content of [A3] in 100 parts by weight of the total epoxy resin exceeded 10 parts by weight, failing to meet condition (3). Therefore, the yellowness and weather resistance of the resin cured product were inferior to those in Examples 1 and 8.

[0152] <Comparative Example 10>

[0153] As shown in Table 1, the resin composition was changed, except that the epoxy resin cured product and prepreg were prepared using the same method as in Example 1. The epoxy resin cured product exhibited good flexural strength, flexural modulus, yellowness, transparency, and tackiness of the prepreg. However, no compounding element [D] was used, and "SmicaExel" PES 5003P (registered trademark) was used as a substitute thermoplastic resin; therefore, the weather resistance of the resin cured product was inferior to that of Example 1.

[0154] [Table 1-1]

[0155]

[0156] [Table 1-2]

[0157]

Claims

1. A prepreg preform comprising a composition of reinforcing fibers and a resin, The resin composition contains the following constituent elements [A] to [D] and satisfies the following conditions (1) to (4). Constituent element [A]: Epoxy resin; Component [B]: Dicyandiamide; Constituent element [C]: A compound having a boiling point of 130°C or higher and a molecular weight m of 50 or higher and 250 or lower, wherein the compound does not have an epoxy group in the molecule and does not substantially have the curing ability of epoxy resin; Constituent element [D]: Phenoxy resin; (1): As a constituent element [A], it includes 10 to 40 parts by weight of [A1] isocyanuric acid type epoxy resin relative to 100 parts by weight of all epoxy resin; (2): As a constituent element [A], relative to 100 parts by weight of all epoxy resin, it includes 10 to 50 parts by weight of [A2] phenolic varnish type epoxy resin. (3): As a constituent element [A], the content of glycidylamine type epoxy resin [A3] is less than 10 parts by mass relative to 100 parts by mass of all epoxy resin; (4): The constituent element [C] is a compound having at least one functional group selected from amide, ketone and hydroxyl groups in the molecule.

2. The prepreg blank according to claim 1 does not substantially contain the [A3] glycidylamine type epoxy resin.

3. The prepreg blank according to claim 1 or 2, wherein the content of the constituent element [B] is 4 to 9 parts by weight relative to 100 parts by weight of the total epoxy resin.

4. The prepreg blank according to claim 1 or 2, comprising element [A], comprising [A4] bisphenol type epoxy resin.

5. A fiber-reinforced composite material, which is formed by curing a prepreg blank according to any one of claims 1 to 4.

6. A fiber-reinforced composite tubular body, which is obtained by molding a prepreg blank according to any one of claims 1 to 4 into a tubular shape.

7. A golf club shaft formed from a tubular body using the fiber-reinforced composite material of claim 6.

8. A fishing rod formed from a tubular body using the fiber-reinforced composite material of claim 6.

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