Prepreg, fiber-reinforced composite material, tubular body made of fiber-reinforced composite material, golf club shaft, fishing rod, automobile structural member, and exterior member

Abstract

To provide a prepreg which is excellent in storage stability and exhibits excellent mechanical characteristics when being formed into a fiber-reinforced composite material, and a fiber-reinforced composite material and a tubular body made of a fiber-reinforced composite material, which use the prepreg.SOLUTION: A prepreg contains a reinforcement fiber and a resin composition, wherein the resin composition contains the following components [A] to [C], and satisfies the following conditions (1) to (3). Component [A]: an epoxy resin, component [B]: dicyandiamide, and component [C]: a boric acid ester compound. Condition (1): 10 to 50 pts.mass of [A1] an epoxy resin represented by the following general formula (I) is contained with respect to 100 pts.mass of the whole epoxy resin, as the component [A], Condition (2): a hydroxyl value of the component [A] is 1.5×10-3 eq / g or less, and condition (3): a component [D]: a curing accelerator is not contained, or even though it is contained, the content is 1.5 pts.mass or less with respect to 100 pts.mass of the whole epoxy resin.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to prepregs, fiber-reinforced composite materials, and tubular bodies made of fiber-reinforced composite materials, which are suitably used for fiber-reinforced composite materials for aerospace applications, general industrial applications, sports applications, etc. The present invention also relates to golf club shafts and fishing rods using the tubular bodies made of fiber-reinforced composite materials, and automotive structural members and exterior members using the fiber-reinforced composite materials.

Background Art

[0002] Fiber-reinforced composite materials using carbon fibers, aramid fibers, etc. as reinforcing fibers are widely used in structural materials for aircraft and automobiles, and sports and general industrial applications such as tennis rackets, golf club shafts, fishing rods, bicycles, and housings by utilizing their high specific strength and specific modulus of elasticity. As the resin composition used for this fiber-reinforced composite material, thermosetting resins are mainly used from the viewpoints of heat resistance and productivity, and among them, epoxy resins are preferably used from the viewpoint of mechanical properties such as adhesiveness with reinforcing fibers.

[0003] In the production of fiber-reinforced composite materials, prepregs in which a carbon fiber base material is impregnated with an epoxy resin in advance are widely used. After laminating or preforming the prepreg, it is heated to cure the epoxy resin to obtain a molded product. The properties required for prepregs are that the molded product exhibits excellent mechanical properties and that the prepreg exhibits excellent storage stability. Current prepregs are reactive even at room temperature and usually require freezing storage. Since this requires the arrangement of freezing equipment and thawing before use, a prepreg that can be stored and handled at room temperature is required.

[0004] As a technique for enhancing storage stability, Patent Document 1 describes that an epoxy resin composition and a prepreg having excellent storage stability can be obtained by blending a borate ester compound.

Prior Art Documents

Patent Documents

[0005] Patent Document 1 Japanese Patent Application Laid-Open No. 2016-148022 Summary of the Invention Problems to be Solved by the Invention

[0006] In the technology of Patent Document 1, when an epoxy resin having self-polymerizability such as a metaxylenediamine type epoxy resin is used as the matrix resin, the effect of improving storage stability is insufficient.

[0007] Therefore, an object of the present invention is to provide a prepreg that is excellent in storage stability even when an epoxy resin having self-polymerizability is used as the matrix resin and exhibits excellent mechanical properties when made into a fiber-reinforced composite material. Means for Solving the Problems

[0008] 1. A prepreg comprising reinforcing fibers and a resin composition, wherein the resin composition contains the following components [A] to [C] and satisfies the following conditions (1) to (3). Component [A]: Epoxy resin Component [B]: Dicyandiamide Component [C]: Borate compound Condition (1): As component [A], [A1]: An epoxy resin represented by the following general formula (I) is contained in an amount of 10 to 50 parts by mass with respect to 100 parts by mass of the total epoxy resin.

[0009] [Chemical Formula]

[0010] (In the formula, R represents arylene which is unsubstituted or has a substituent, or cyclopentanediy, cyclohexanediy or norbornanediy which is unsubstituted or has a substituent.) Condition (2): The hydroxyl value of component [A] is 1.5×10 -3It is below eq / g. Condition (3): Component [D]: Does not contain a curing accelerator, or even if it contains one, its content is 1.5 parts by mass or less with respect to 100 parts by mass of the total epoxy resin. The prepreg according to 1 above, which does not contain component [D]. 3. The prepreg according to 1 or 2 above, wherein the content of component [C] satisfies 0.01 ≦ (content of component [C] / content of component [A1]) ≦ 0.05. 4. A fiber-reinforced composite material formed by molding the prepreg according to any one of 1 to 3 above. 5. A tubular body made of a fiber-reinforced composite material formed by molding the prepreg according to any one of 1 to 3 above. 6. A golf club shaft using the tubular body made of the fiber-reinforced composite material according to 5 above. 7. A fishing rod using the tubular body made of the fiber-reinforced composite material according to 5 above. 8. An automobile structural member using the fiber-reinforced composite material according to 4 above. 9. An exterior member using the fiber-reinforced composite material according to 4 above.

Advantages of the Invention

[0011] According to the present invention, even when an epoxy resin having self-polymerizability is used as the matrix resin, a prepreg having excellent storage stability and exhibiting excellent mechanical properties when formed into a fiber-reinforced composite material, and a fiber-reinforced composite material, a tubular body made of the fiber-reinforced composite material, a golf club shaft, a fishing rod, an automobile structural member, and an exterior member using the prepreg can be obtained.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in detail.

[0013] The prepreg of the present invention contains a resin composition and reinforcing fibers, and the resin composition is used as a matrix resin. It is preferably composed of a resin composition and reinforcing fibers. The resin composition contains components [A] to [C].

[0014] Component [A] in the present invention is an epoxy resin contained in the resin composition. Examples of such epoxy resins include bisphenol type, isocyanuric acid type, phenol novolac type, cresol novolac type, dicyclopentadiene type, biphenyl type, diaminodiphenylmethane type, diaminodiphenylsulfone type, aminophenol type, metaxylenediamine type, 1,3-bisaminomethylcyclohexane type, hydantoin type, sorbitol type, trishydroxyphenylmethane type, and tetraphenylol ethane type epoxy resins.

[0015] In order to satisfy condition (1) in the present invention, as component [A], it is necessary to contain [A1]: an epoxy resin represented by the above general formula (I). By containing [A1], the strength and elastic modulus of the resin cured product are improved, and it becomes possible to obtain a fiber-reinforced composite material having excellent mechanical properties.

[0016] In order to enhance the heat resistance and mechanical properties of the fiber-reinforced composite material, from the viewpoint that a rigid ring structure may be introduced into the crosslinked structure in the resin cured product, as R in the general formula (I), arylene, cyclopentanediyl, cyclohexanediyl, or norbornanediyl is selected. The arylene may be unsubstituted without being substituted by a functional group, or may have a substituent substituted by a functional group. The same applies to cyclopentanediyl, cyclohexanediyl, or norbornanediyl.

[0017] Also, when R in the general formula (I) has a substituent, examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a methoxy group, an ethoxy group, a phenoxy group, an acetoxy group, a formyl group, an acetyl group, a methoxycarbonyl group, an ethoxycarbonyl group, a nitro group, a cyano group, an acetamide group, a fluoro group, a chloro group, a bromo group, an iodo group, a trifluoromethyl group, etc., but are not limited thereto.

[0018] In the resin composition, 10 to 50 parts by mass of component [A1] is contained with respect to 100 parts by mass of the total epoxy resin contained as component [A]. Regarding the lower limit, it is preferably 20 parts by mass or more, more preferably 25 parts by mass or more. Regarding the upper limit, it is preferably 45 parts by mass or less, more preferably 40 parts by mass or less. If the content of component [A1] is at least the above lower limit value, the strength and elastic modulus of the resin cured product are excellent. Further, since component [A1] has an action of promoting the self-polymerization reaction of the epoxy resin, by setting the content of component [A1] to be not more than the above upper limit value, the storage stability of the epoxy resin composition and prepreg is excellent.

[0019] Examples of component [A1] include metaxylene diamine type epoxy resin, para-xylene diamine type epoxy resin, 1,3-bis(aminomethyl)cyclohexane type epoxy resin, 1,4-bis(aminomethyl)cyclohexane type epoxy resin, etc., and it is more preferable to use metaxylene diamine type epoxy resin.

[0020] Examples of commercially available products of metaxylene diamine type epoxy resin include "TETRAD (registered trademark)"-X (manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0021] Examples of commercially available products of 1,3-bis(aminomethyl)cyclohexane type epoxy resin include "TETRAD (registered trademark)"-C (manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0022] Condition (2) in the present invention defines that the hydroxyl value of component [A] is 1.5×10 -3 eq / g or less. More specifically, when component [A] consists of a single epoxy resin, it is determined for the hydroxyl value of the resin, and when component [A] consists of a plurality of epoxy resins, for example, when it consists of a plurality of components [A1], or when it has component [A2] which is an epoxy resin other than component [A1] in addition to component [A1], it is determined for the hydroxyl value of the resin composition in which those epoxy resins are mixed. The hydroxyl value of the resin or resin composition consisting only of such component [A] is 1.5×10 -3By using those with a hydroxyl value of 1 eq / g or less, a resin composition and a prepreg excellent in storage stability can be obtained without impairing the effect of improving storage stability. Here, the hydroxyl value is measured according to JIS K0070 (1992).

[0023] To satisfy condition (2), it is preferable to use an epoxy resin having a hydroxyl value of 1.5×10 -3 eq / g or less. Examples of the epoxy resin having a hydroxyl value of 1.5×10 -3 eq / g or less include, in addition to component [A1], bisphenol A type epoxy resins having an epoxy equivalent of 200 g / eq or less, bisphenol F type epoxy resins having an epoxy equivalent of 180 g / eq or less, phenol novolac type epoxy resins, cresol novolac type epoxy resins, dicyclopentadiene type epoxy resins, biphenyl type epoxy resins, and the like.

[0024] Examples of commercially available products of bisphenol A type epoxy resins having an epoxy equivalent of 200 g / eq or less include "jER (registered trademark)" 825, 828 (manufactured by Mitsubishi Chemical Corporation), "EPICLON (registered trademark)" 850 (manufactured by DIC Corporation), "Epotoate (registered trademark)" YD-128 (manufactured by Nippon Steel Chemical & Materials Co., Ltd.), and "D.E.R. (registered trademark)" -331, 332 (manufactured by The Dow Chemical Company), and the like.

[0025] Examples of commercially available products of bisphenol F type epoxy resins having an epoxy equivalent of 180 g / eq or less include "Araldite (registered trademark)" GY282 (manufactured by Huntsman Advanced Materials Corporation), "jER (registered trademark)" 806, 807 (manufactured by Mitsubishi Chemical Corporation), "EPICLON (registered trademark)" 830 (manufactured by DIC Corporation), and "Epotoate (registered trademark)" YDF-170 (manufactured by Nippon Steel Chemical & Materials Co., Ltd.), and the like.

[0026] Examples of commercially available phenol novolac type epoxy resins include "jER (registered trademark)" 152, 154 (both manufactured by Mitsubishi Chemical Corporation), EPPN-201 (manufactured by Nippon Kayaku Co., Ltd.), "EPICLON (registered trademark)" N-740, N-770 (softening point: 70°C), N-775 (softening point: 75°C, all manufactured by DIC Corporation), and the like.

[0027] Examples of commercially available cresol novolac type epoxy resins include "EPICLON (registered trademark)" N-660 (softening point: 66°C), N-665 (softening point: 70°C), N-670 (softening point: 73°C), N-673 (softening point: 78°C), N-680 (softening point: 87°C), N-690 (softening point: 93°C), N-695 (softening point: 95°C, all manufactured by DIC Corporation), and the like.

[0028] Examples of commercially available dicyclopentadiene type epoxy resins include "EPICLON (registered trademark)" HP-7200, HP-7200L, HP-7200H, HP-7200HH, HP-7200HHH (all manufactured by DIC Corporation), and the like.

[0029] Examples of commercially available biphenyl type epoxy resins include "jER (registered trademark)" YX4000, YX4000H, YX4000HS (all manufactured by Mitsubishi Chemical Corporation), and the like.

[0030] Component [B] in the present invention is dicyandiamide. Dicyandiamide is excellent in imparting high mechanical properties and heat resistance to the cured product of epoxy resin, and is widely used as a curing agent for various epoxy resins. In addition, since it has excellent storage stability of the epoxy resin composition, it can be preferably used. Examples of commercially available dicyandiamide include DICY7, DICY15 (both manufactured by Mitsubishi Chemical Corporation), and the like.

[0031] In the present invention, since the cured resin has excellent mechanical properties, the content of component [B] is preferably 2 to 12 parts by mass with respect to 100 parts by mass of the total epoxy resin. The lower limit is more preferably 4 parts by mass or more, and the upper limit is more preferably 10 parts by mass or less.

[0032] As condition (3) in the present invention, component [D]: a curing accelerator is not contained, or even if it is contained, its content is 1.5 parts by mass or less with respect to 100 parts by mass of the total epoxy resin. Further, even if component [D] is contained, it is preferably 1 part by mass or less, and more preferably 0.1 part by mass or less with respect to 100 parts by mass of the total epoxy resin. By using component [D] in the above amount, the storage stability of the epoxy resin composition and prepreg is excellent.

[0033] Examples of component [D] include urea compounds and imidazole compounds, and urea compounds can be particularly preferably used from the viewpoint of the storage stability of the resin composition.

[0034] Examples of the urea compound include 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, phenyldimethylurea, and toluene bisdimethylurea.

[0035] As commercially available products of aromatic urea compounds, DCMU99 (manufactured by Hodogaya Chemical Co., Ltd.) and "Omicure (registered trademark)" 24 (manufactured by PTI Japan Co., Ltd.) can be used.

[0036] Component [C] in the present invention is a borate ester compound. By using component [C] and component [A1] in combination, the self-polymerization reaction of the epoxy resin by component [A1] at the storage temperature can be suppressed, so that the storage stability of the prepreg is improved. The mechanism is not clear, but since component [C] has Lewis acidity, it is considered that component [C] interacts with the tertiary amine contained in the molecular structure of component [A1] and reduces the reactivity of the tertiary amine.

[0037] The content of component [C] preferably satisfies the relationship of 0.01 ≦ (content of component [C] / content of component [A1]) ≦ 0.05 between component [C] and component [A1]. Regarding the lower limit of the aforementioned formula, it is more preferably 0.02 or more, and regarding the upper limit, it is more preferably 0.045 or less. By the content of component [C] / content of component [A1] satisfying the above range, the balance between the storage stability and mechanical properties of the prepreg is excellent.

[0038] Examples of such component [C] include alkyl borate esters such as trimethyl borate, triethyl borate, tributyl borate, tri-n-octyl borate, tri(triethylene glycol methyl ether) borate, tricyclohexyl borate, and trimenthyl borate; aromatic borate esters such as tri-o-cresyl borate, tri-m-cresyl borate, tri-p-cresyl borate, and triphenyl borate; and tri(1,3-butanediol) diborate, tri(2-methyl-2,4-pentanediol) diborate, trioctylene glycol diborate, and the like.

[0039] Also, as the borate ester, a cyclic borate ester having a cyclic structure in the molecule can be used. Examples of the cyclic borate ester include tris-o-phenylene bisborate, bis-o-phenylene pyroborate, bis-2,3-dimethylethylene phenylene pyroborate, bis-2,2-dimethyltrimethylene pyroborate, and the like.

[0040] Examples of commercially available products of component [C] include "Curedact (registered trademark)" L-01B, L-07N, L-07E (all of the above are from Shikoku Kasei Kogyo Co., Ltd.) (compositions containing 5 parts by mass of a borate ester compound), and the like.

[0041] In the resin composition used for the prepreg of the present invention, a specific low molecular compound may be blended as an additive within a range that does not impair the effects of the present invention. The specific low molecular compound here is a compound having a boiling point of 130°C or higher and a molecular weight m of 50 or more and 250 or less, having no epoxy group in the molecule, and having no curing ability for the epoxy resin. Compounds such as amines, phenols that can undergo an addition reaction with the epoxy resin, acid anhydrides that can copolymerize with the epoxy resin, imidazoles that can be initiators for the self-polymerization reaction of the epoxy resin, aromatic urea compounds, and tertiary amine compounds are compounds having a curing ability for the epoxy resin and are not included in the low molecular compound here. Here, "having no curing ability for the epoxy resin" means a property of not chemically reacting with the epoxy resin and not participating in the self-polymerization of the epoxy resin.

[0042] It is considered that the above low molecular compound exists in the voids without being incorporated into the crosslinked structure formed by the reaction of the epoxy resin and dicyandiamide, and this state is maintained even after the curing of the epoxy resin. As a result, it is considered that the elastic modulus of the obtained cured epoxy resin product increases. Further, by blending the above low molecular compound, not only a high elastic modulus but also a cured epoxy resin product having a high elongation and high strength can be obtained.

[0043] Examples of such low molecular compounds include amides such as N-methylformamide, N-methylacetamide, 2-pyrrolidone, N-methylpropionamide, N-ethylacetamide, N-methylacetanilide, and N,N'-diphenylacetamide. These compounds may be used alone or in appropriate combination.

[0044] In the resin composition used for the prepreg of the present invention, a thermoplastic resin may be blended as long as the effects of the present invention are not impaired. By blending a thermoplastic resin into the resin composition, it is possible to control the viscosity of the resin composition, the tackiness of the prepreg, and the fluidity of the resin composition when the prepreg is heat-cured, without impairing the heat resistance of the fiber-reinforced composite material. As such a thermoplastic resin, a thermoplastic resin having compatibility with an epoxy resin and having a hydrogen-bonding functional group capable of improving the adhesiveness between the resin and the reinforcing fiber is preferably used.

[0045] Examples of the reinforcing fiber used for the prepreg and the fiber-reinforced composite material of the present invention preferably include carbon fiber, graphite fiber, aramid fiber, glass fiber, etc., and carbon fiber is particularly preferred. The form and arrangement of the reinforcing fiber are not limited. For example, long fibers aligned in one direction, single tows, woven fabrics, knits, and fiber structures such as braids are used. As the reinforcing fiber, two or more types of carbon fibers, glass fibers, aramid fibers, boron fibers, PBO fibers, high-strength polyethylene fibers, alumina fibers, and silicon carbide fibers may be used in combination.

[0046] Specific examples of the carbon fiber include acrylic-based, pitch-based, and rayon-based carbon fibers, and acrylic-based carbon fibers having a particularly high tensile strength are preferably used.

[0047] As the form of the carbon fiber, twisted yarns, untwisted yarns, and non-twisted yarns can be used. However, in the case of twisted yarns, since the orientation of the filaments constituting the carbon fiber is not parallel, it causes a decrease in the mechanical properties of the obtained carbon fiber-reinforced composite material. Therefore, untwisted yarns or non-twisted yarns having a good balance between the moldability and strength characteristics of the carbon fiber-reinforced composite material are preferably used.

[0048] The carbon fiber preferably has a tensile elastic modulus in the range of 200 to 440 GPa. The tensile elastic modulus of the carbon fiber is affected by the crystallinity of the graphite structure constituting the carbon fiber, and the higher the crystallinity, the higher the elastic modulus. Being within this range is preferable because all of the rigidity and strength of the carbon fiber reinforced composite material are balanced at a high level. A more preferable tensile elastic modulus is within the range of 230 to 400 GPa, and even more preferably within the range of 260 to 370 GPa. Here, the tensile elastic modulus of the carbon fiber is a value measured in accordance with JIS R7601 (2006).

[0049] The prepreg of the present invention can be manufactured by various known methods. For example, the prepreg can be manufactured by a hot melt method in which the resin composition is made to have a low viscosity by heating without using an organic solvent and then impregnated into the reinforcing fiber.

[0050] In the hot melt method, methods such as directly impregnating the reinforcing fiber with the resin composition whose viscosity has been lowered by heating, or first preparing a release paper sheet with a resin film in which the resin composition has once been coated on a release paper or the like, and then overlapping the resin film from both sides or one side of the reinforcing fiber onto the reinforcing fiber side and impregnating the reinforcing fiber with the resin composition by heating and pressurizing can be used.

[0051] The content rate of the reinforcing fiber 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 such a fiber mass content rate is small, the amount of resin is too large, and it is difficult to obtain the advantages of a fiber reinforced composite material excellent in specific strength and specific elastic modulus. Also, when molding the fiber reinforced composite material, the amount of heat generated during curing may become too high. On the other hand, if the fiber mass content rate is too large, poor impregnation of the resin may occur, and the resulting composite material may have many voids. Also, there is a risk of impairing the tackiness of the prepreg.

[0052] The fiber-reinforced composite material or tubular body made of a fiber-reinforced composite material of the present invention can be manufactured, for example, by laminating the prepreg of the present invention described above in a predetermined form and applying pressure and heat to cure the resin. Here, as a method of applying heat and pressure, a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, an internal pressure molding method, etc. are adopted.

[0053] Among the molding methods of the tubular body made of a fiber-reinforced composite material, the wrapping tape method is particularly preferably used. The wrapping tape method is a method of winding a prepreg around a mandrel or the like to obtain a cylindrical molded body. Specifically, it is a method of winding a prepreg around a mandrel, winding a wrapping tape made of a thermoplastic resin film around the outer periphery thereof for fixing the prepreg and applying pressure, heating and curing the resin in an oven, and then removing the mandrel to obtain a cylindrical molded body, which is suitable for producing tubular bodies such as golf club shafts and fishing rods.

[0054] When the resin composition according to the present invention is used as the matrix resin of the prepreg, the cured product can have excellent mechanical properties, so the tubular body made of the fiber-reinforced composite material of the present invention can exhibit excellent bending strength.

[0055] The fiber-reinforced composite material or tubular body made of a fiber-reinforced composite material of the present invention can be widely used in aerospace applications, general industrial applications and sports applications. More specifically, in general industrial applications, it is preferably used for structural members such as automobiles, ships and railway vehicles, and exterior members for automobiles, ships, railways and buildings. In sports applications, it is preferably used for golf club shafts, fishing rods, tennis and badminton rackets. Among them, the tubular body made of the fiber-reinforced composite material of the present invention can be preferably used for golf club shafts and fishing rods.

[0056] The upper and lower limits of the numerical ranges described above can be arbitrarily combined unless otherwise specified.

Examples

[0057] Hereinafter, the present invention will be described in detail with reference to examples. However, the scope of the present invention is not construed as being limited to these examples. The unit "part" of the composition ratio means parts by mass unless otherwise noted. In addition, the measurement of various properties (physical properties) was carried out in an environment of a temperature of 23 °C and a relative humidity of 50% unless otherwise noted. Also, in the table, the unit of the amount of each component is parts by mass in all cases.

[0058] <Materials Used in Examples and Comparative Examples> (1) Reinforcing Fiber "Torayca (registered trademark)" T1100G-24K (number of fibers: 24,000, tensile modulus of elasticity: 324 GPa, density: 1.8 g / cm 3 , manufactured by Toray Industries, Inc.) (2) Component [A]: Epoxy Resin · Component [A1]: Epoxy resin represented by the general formula (I) [A1]-1 "TETRAD (registered trademark)"-X (meta-xylenediamine type epoxy resin, epoxy equivalent: 90, manufactured by Mitsubishi Gas Chemical Company, Inc.) · Component [A2]: Other epoxy resins [A2]-1 "jER (registered trademark)" 828 (bisphenol A type epoxy resin, epoxy equivalent: 189 g / eq, manufactured by Mitsubishi Chemical Corporation) [A2]-2 "EPICLON (registered trademark)" 830 (bisphenol F type epoxy resin, epoxy equivalent: 172 g / eq, manufactured by DIC Corporation) [A2]-3 "EPICLON (registered trademark)" N-775 (phenol novolac type epoxy resin, epoxy equivalent: 189 g / eq, manufactured by DIC Corporation) [A2]-4 "EPICLON (registered trademark)" HP-7200H (dicyclopentadiene type epoxy resin, epoxy equivalent: 278 g / eq, manufactured by DIC Corporation) [A2]-5 "jER (registered trademark)" 1001 (bisphenol A type epoxy resin, epoxy equivalent: 475 g / eq, manufactured by Mitsubishi Chemical Corporation) [A2]-6 "Epotoat (registered trademark)" YDF2001 (bisphenol F type epoxy resin, epoxy equivalent: 485, manufactured by Nippon Steel Chemical & Material Co., Ltd.) [A2]-7 "Denacol (Registered Trademark)" EX-614B (Sorbitol-type epoxy resin, epoxy equivalent: 173, manufactured by Nagase ChemteX Corporation) (3) Component [B]: Dicyandiamide [B]-1 DICY7 (Dicyandiamide, manufactured by Mitsubishi Chemical Corporation) (4) Other curing agents "Cureduct (Registered Trademark)" P-0505 (Epoxy imidazole adduct, manufactured by Shikoku Kasei Kogyo Co., Ltd.) "ANCAMINE (Registered Trademark)" 2049 (Bis(4-amino-3-methylcyclohexyl)methane, manufactured by Evonik Corporation) (5) Component [D]: Curing accelerator [D]-1 DCMU99 (3-(3,4-Dichlorophenyl)-1,1-dimethylurea, manufactured by Hodogaya Chemical Co., Ltd.).

[0059] (6) Component [C]: Borate compound [C]-1 "Cureduct (Registered Trademark)" L-07N (Composition containing 5% by mass of borate compound, manufactured by Shikoku Kasei Kogyo Co., Ltd.) <Method for preparing resin composition> Table 1 shows the compositions of each example and comparative example.

[0060] (1) Preparation of curing agent masterbatch In each example and comparative example, among the components of each example shown in the table, 10 parts by mass of an epoxy resin ([A1]-1, [A2-1, [A2]-2, [A2]-7, any one of them) that is liquid at room temperature was prepared (10 parts by mass with respect to 100 parts by mass of all epoxy resins contained in the resin composition). To this, component [B]: dicyandiamide was added in the amounts shown in the table respectively, and kneaded at room temperature. The mixture was passed through a three-roll mill twice to prepare a curing agent masterbatch.

[0061] (2) Preparation of resin composition Among the components of each example shown in the table, excluding the amount contained in 10 parts by mass of the liquid epoxy resin used in the above (1) and component [A1], the epoxy resin related to component [A2] was put into a beaker and heated to 150 °C with kneading to dissolve it. Then, the temperature was lowered to 120 °C, and after adding component [A1] shown in each example of the table, it was dissolved with kneading. Next, while continuing the kneading, the temperature was lowered to 55 - 65 °C, and then component [C] of each example of the components and amounts shown in the table, the curing agent master prepared in the above (1), and component [D] of each example of the components and amounts shown in the table were added, and kneaded at the same temperature for 30 minutes to obtain a resin composition. However, for Comparative Examples 8 and 9, instead of using the above curing agent master, "Cureduct (registered trademark)" P-0505 or "ANCAMINE (registered trademark)" 2049 was used as the curing agent.

[0062] Also, the preparation of the resin composition containing only component [A] was carried out by putting component [A2] of each example of the components and amounts shown in the table into a beaker, heating to 150 °C with kneading to dissolve it, then lowering the temperature to 120 °C, and adding component [A1] of each example of the components and amounts shown in the table and dissolving it with kneading.

[0063] <Method for producing resin cured product> After degassing the resin composition prepared according to the above <Method for preparing resin composition> in a vacuum, it was set in a mold to a thickness of 2 mm with a 2 mm thick "Teflon (registered trademark)" spacer, heated from 30 °C at a rate of 1.7 °C / min, held at 90 °C for 1 hour after reaching the temperature, then heated at a rate of 2.0 °C / min, and cured for 2 hours after reaching the temperature of 135 °C to obtain a plate-shaped resin cured product with a thickness of 2 mm.

[0064] <Method for producing prepreg> The resin composition prepared according to the above <Method for preparing resin composition> and containing compounds other than component [A] was applied onto release paper using a knife coater to produce two resin films with a resin basis weight of 31 g / m 2 Next, two fiber fabrics with a fiber basis weight of 125 g / m 2The resin film was overlaid on each of the two sides of the reinforcing fibers (the above-mentioned "Torayca (registered trademark)" T1100G-24K) arranged in one direction so as to form a sheet shape, and heated and pressed under the conditions of a temperature of 110°C and a maximum pressure of 2 MPa to impregnate the resin composition, thereby obtaining a prepreg. However, for Comparative Example 9, heating and pressing were performed under the conditions of a temperature of 40°C and a maximum pressure of 2 MPa to impregnate the resin composition.

[0065] <Various evaluation methods> (1) Measurement of the hydroxyl value of component [A] Using the resin composition containing only component [A] prepared according to the above <Method for preparing resin composition>, the hydroxyl value was measured according to JIS K0070 (1992). When the measured hydroxyl value is 1.5×10 -3 eq / g or less, it was marked as "〇", and when it is greater than 1.5×10 -3 eq / g, it was marked as "×".

[0066] (2) Three-point bending measurement of the resin cured product From the resin cured product with a thickness of 2 mm prepared according to the above <Method for preparing resin cured product>, a test piece with a width of 10 mm and a length of 60 mm was cut out. 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 the number of samples n = 6, the average values of the strength and elastic modulus when performing three-point bending according to JIS K7171 (1994) were taken as the flexural strength and flexural modulus of the resin cured product, respectively.

[0067] (3) Evaluation of the storage stability of the prepreg The storage stability of the prepreg was determined by the increase amount (ΔTg) of the glass transition temperature (Tg) when the prepreg was cut into a 10 cm square and left at 40°C for 7 days. The glass transition temperature (Tg) was measured by weighing 8 mg of the prepreg before and after storage into sample pans respectively, using a differential scanning calorimeter (Q-2500: manufactured by TA Instruments), and heating from -40°C to 100°C at a rate of 10°C / min. The midpoint of the inflection point of the obtained exothermic curve was taken as Tg. Here, ΔTg was obtained by the difference in Tg before and after storage at 40°C for 7 days.

[0068] <Example 1> Among epoxy resins, 30 parts by mass of "TETRAD (registered trademark)"-X was used as component [A1], 35 parts by mass of "jER (registered trademark)" 828 and 35 parts by mass of "EPICLON (registered trademark)" N-775 were used as other epoxy resins (component [A2]), 8.4 parts by mass of DICY7 was used as component [B], and 12 parts by mass of "Cureduct (registered trademark)" L-07N was used as component [C]. A resin composition was prepared according to the above <Method for preparing resin composition>. The hydroxyl value of the resin composition containing only component [A] was 1.5×10 -3 eq / g or less.

[0069] From the obtained resin composition, a resin cured product was prepared according to the <Method for preparing resin cured product>. When the flexural strength and flexural modulus of this resin cured product were measured, the flexural strength was 173 MPa and the flexural modulus was 3.8 GPa, and the physical properties of the resin cured product were good.

[0070] Furthermore, a prepreg was prepared from the obtained resin composition according to the <Method for preparing prepreg> and measured according to "(3) Storage stability evaluation of prepreg" in the <Various evaluation methods>. As a result, ΔTg was 7.3°C and the storage stability of the prepreg was good.

[0071] <Examples 2 to 8> Resin cured products and prepregs were prepared in the same manner as in Example 1, except that the composition was changed as shown in Table 1. For each example, the hydroxyl value of the resin composition containing only component [A] was 1.5×10 -3 eq / g or less, and the flexural strength, flexural modulus of the resin cured product, and the storage stability of the prepreg were as shown in Table 1, and all were good.

[0072] <Comparative Examples 1 to 3> The composition shown in Table 1 was used, and resin cured products and prepregs were prepared in the same manner as in Example 1. The physical property evaluation results are shown together in Table 1 (the same applies to the following comparative examples). The flexural strength and flexural modulus of the resin cured product were good. However, the hydroxyl value of the resin composition containing only component [A] was 1.5×10-3 Since it was greater than eq / g and did not satisfy condition (2), the storage stability of the prepreg was poor compared to Example 1.

[0073] <Comparative Example 4> With the composition shown in Table 1, a resin cured product and a prepreg were produced in the same manner as in Example 1 except for this. The hydroxyl value of the resin composition containing only component [A] was 1.5×10 -3 eq / g or less, and the flexural strength and flexural modulus of the resin cured product were good. However, since the content of component [A1] exceeded 50 parts by mass in 100 parts by mass of the total epoxy resin and did not satisfy condition (1), the storage stability of the prepreg was poor compared to Example 3.

[0074] <Comparative Example 5> With the composition shown in Table 1, a resin cured product and a prepreg were produced in the same manner as in Example 1 except for this. The hydroxyl value of the resin composition containing only component [A] was 1.5×10 -3 eq / g or less, and the storage stability of the prepreg was good. However, since the content of component [A] was less than 10 parts by mass in 100 parts by mass of the total epoxy resin and did not satisfy condition (1), the flexural strength and flexural modulus of the resin cured product were poor compared to Example 6.

[0075] <Comparative Example 6> With the composition shown in Table 1, a resin cured product and a prepreg were produced in the same manner as in Example 1 except for this. The hydroxyl value of the resin composition containing only component [A] was 1.5×10 -3 eq / g or less, and the flexural strength and flexural modulus of the resin cured product were good. However, since the content of component [D] exceeded 1.5 parts by mass in 100 parts by mass of the total epoxy resin and did not satisfy condition (3), the storage stability of the prepreg was poor compared to Example 1 and Example 4.

[0076] <Comparative Example 7> With the composition shown in Table 1, a resin cured product and a prepreg were produced in the same manner as in Example 1 except for this. The hydroxyl value of the resin composition containing only component [A] was 1.5×10 -3It was below 1.5 eq / g, and the flexural strength and flexural modulus of the cured resin were good. However, since Component [C] was not blended, the storage stability of the prepreg was poor compared to Example 1.

[0077] <Comparative Example 8> With the composition shown in Table 1, a resin composition was prepared according to the above <Method for Preparing Resin Composition>, and from the obtained resin composition, a cured resin was prepared according to the <Method for Preparing Cured Resin>, and further, a prepreg was prepared from the obtained resin composition according to the <Method for Preparing Prepreg>. The hydroxyl value of the resin composition containing only Component [A] was 1.5×10 -3 eq / g or less, and the storage stability of the prepreg was good. However, since "Cureduct (registered trademark)" P-0505 was used as another curing agent without using Component [B], the flexural strength and flexural modulus of the cured resin were lower than those of Examples 5, 6, and 8.

[0078] <Comparative Example 9> With the composition shown in Table 1, a resin composition was prepared according to the above <Method for Preparing Resin Composition>, and further, a prepreg was prepared from the obtained resin composition according to the <Method for Preparing Prepreg>. The hydroxyl value of the resin composition containing only Component [A] was 1.5×10 -3 eq / g or less. Since "ANCAMINE (registered trademark)" 2049 with high reactivity was used as the curing agent without using Component [B], a cured resin according to the <Method for Preparing Cured Resin> could not be obtained. Also, when the stability was evaluated according to "(2) Evaluation of Storage Stability of Prepreg", since the prepreg was solidified, it could be said that the storage stability of the prepreg was poor compared to Example 1.

[0079]

Table 1

Claims

1. A prepreg comprising a reinforcing fiber and a resin composition, wherein the resin composition contains the following components [A] to [C] and satisfies the following conditions (1) to (3). Component [A]: Epoxy resin Component [B]: Dicyandiamide Component [C]: Borate compound Condition (1): As component [A], [A1]: An epoxy resin represented by the following general formula (I) is contained in an amount of 10 to 50 parts by mass with respect to 100 parts by mass of the total epoxy resin. 【Chemical 1】 (In the formula, R represents an arylene which is unsubstituted or has a substituent, or a cyclopentanediyl, cyclohexanediyl or norbornanediyl which is unsubstituted or has a substituent.) Condition (2): The hydroxyl value of component [A] is 1.5 × 10 －３ eq / g or less. Condition (3): Component [D]: Does not contain a curing accelerator, or even if it contains one, its content is 1.5 parts by mass or less with respect to 100 parts by mass of the total epoxy resin.

2. The prepreg according to claim 1, which does not contain component [D].

3. The prepreg according to claim 1, wherein component [A1] and component [C] satisfy the relationship of 0.01 ≦ (content of component [C] / content of component [A1]) ≦ 0.

05.

4. A fiber-reinforced composite material formed by molding the prepreg according to any one of claims 1 to 3.

5. A tubular body made of a fiber-reinforced composite material formed by molding the prepreg according to any one of claims 1 to 3.

6. A golf club shaft using the tubular body made of the fiber-reinforced composite material according to claim 5.

7. A fishing rod using the tubular body made of the fiber-reinforced composite material according to claim 5.

8. An automobile structural member using the fiber-reinforced composite material according to claim 4.

9. An exterior member using the fiber-reinforced composite material according to claim 4.