JP2003277532A - Prepreg and tubular product made of fiber reinforced composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg which gives a fiber reinforced composite material having excellent strength properties against compressive stress from the nonfiber direction, molds a tubular product made of the fiber reinforced composite material exhibiting excellent torsional strength, and has excellent handling properties. <P>SOLUTION: The prepreg is composed of (A) a constituting element of a carbon fiber having a surface area ratio to be measured by an atomic force microscope of 1.00-1.10 and a tensile modulus of 330 GPa-1,000 GPa and (B) a constituting element of an epoxy resin composition comprising an epoxy resin and a curing agent and, simultaneously, has a compressive modulus of a resin cured product to be obtained by heat curing the constituting element (B) of 2.3-3.4 GPa and a nominal compressive strain at break of ≥50%. The tubular product made of the fiber reinforced composite material comprises a layer obtained by heat curing the prepreg. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a prepreg which is an intermediate base material for producing a fiber-reinforced composite material suitable for sports applications, aerospace applications, and general industrial applications, and fibers obtained by heat-curing the prepreg. The present invention relates to a tubular body made of a reinforced composite material.

[0002]

2. Description of the Related Art Carbon fiber reinforced composite materials composed of carbon fibers and matrix resins are particularly excellent in mechanical strength characteristics. Therefore, they are used for sports purposes such as golf club shafts, fishing rods, and tennis and badminton rackets. It is widely used for aerospace applications and general industrial applications. In these applications, long fiber types are often used as carbon fibers.

Various methods are used for producing a fiber-reinforced composite material, and a method using a prepreg which is a sheet-shaped intermediate base material in which carbon fiber is impregnated with a matrix resin is widely used. In this method, a fiber-reinforced composite tubular body is obtained by laminating a plurality of prepregs and then heating them.

Fiber reinforced composite material tubular bodies for sports, that is, golf club shafts, fishing rods, and the like, are fields in which weight reduction is particularly required. When reducing the weight of a fiber-reinforced composite material, in order to make its rigidity appropriate,
It is effective to apply a reinforcing fiber having a high elastic modulus, but particularly when an attempt is made to apply a reinforcing fiber having a high elastic modulus such that the tensile elastic modulus is 330 GPa or more, the strength such as the torsional strength of the tubular body is increased. May run short.

In the past, Japanese Patent Laid-Open No. 2000-51411 has been used.
As disclosed in Japanese Patent Laid-Open Publication No. WO99 / 119407, International Publication No. WO00 / 44017, and the like, a method of improving the strength of a tubular body by applying an epoxy resin composition having a specific composition has been proposed. However,
Especially, in order to solve the lack of strength in the case of applying a reinforcing fiber having a high elastic modulus with a tensile elastic modulus of 330 GPa or more, the effect was not yet sufficient.

Further, as the matrix resin of the carbon fiber reinforced composite material, an epoxy resin composition is preferably used in view of its excellent mechanical properties, heat resistance and good adhesion to carbon fiber.

In a carbon fiber reinforced composite material, the tensile strength in the same direction as the fiber (0 # tensile strength) is generally high because it reflects the high tensile strength of the carbon fiber, while the compressive strength in the same direction as the fiber (0 # tensile strength) is high. Compressive strength) is low compared to 0 # tensile strength, and several approaches have been disclosed to improve this.

For example, Japanese Unexamined Patent Publication No. 2001-131833 discloses a method for improving the compressive strength of carbon fiber itself in the fiber direction, but the manufacturing cost tends to be high and the obtained compressive strength is high. Had problems such as not being enough.

On the other hand, as an attempt to improve the 0 # compressive strength by improving the matrix resin, Japanese Patent Laid-Open No. 11-17
A method for improving the flexural modulus of the matrix resin as disclosed in Japanese Patent Laid-Open No. 1976, etc. is known, and the effect of improving the 0 # compressive strength has been recognized.

However, in a carbon fiber reinforced composite material used as an actual member, a compressive stress may be applied in a direction in which the angle with the fiber direction is not 0 # but a constant angle of less than 90 #. Many. Even when it is considered that 0 # compressive stress is applied by design, the fiber orientation is locally bent due to the shape of the member, or when the carbon fiber woven fabric is used, it is due to the presence of the weft. The fibers often meander, and when compressive stress is applied to such a portion, the compressive stress is applied in a direction at a constant angle of less than 90 # with respect to the fiber direction. In such a case, the strength may be insufficient only by improving the 0 # compression strength as described above.

[0011]

The object of the present invention is to solve the problems of the prior art, to obtain a carbon fiber reinforced composite material having excellent strength characteristics, and to provide a prepreg having excellent handleability. The present invention provides a high-strength fiber-reinforced composite material tubular body obtained by using a prepreg.

[0012]

In order to achieve the above object, the present invention has the following constitution. That is, the compression elastic modulus of a resin cured product composed of the following constituent elements (A) and (B) and obtained by heating and curing the constituent element (B) has a compressive elastic modulus of 2.3 to 3.
A prepreg characterized by a nominal strain of 4 GPa and a compression strain of 50% or more. (A) The surface area ratio measured by an atomic force microscope is 1.
00 to 1.10 and a tensile elastic modulus of 330 to 10
Carbon fiber that is 00 GPa. (B) An epoxy resin composition containing an epoxy resin and a curing agent.

Further, there is provided a tubular body made of a fiber reinforced composite material, which comprises a layer formed by heating and curing the prepreg.

Further, the present invention is a tubular body made of a fiber-reinforced composite material, which comprises a resin cured product obtained by heating and curing the constituent element (B) and the constituent element (A). (A) The surface area ratio measured by an atomic force microscope is 1.
00 to 1.10 and a tensile elastic modulus of 330 to 10
Carbon fiber that is 00 GPa

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention requires, as described below, an uncured epoxy resin whose cured elastic modulus and nominal strain at the time of compressive fracture are controlled within a specific range. By curing and molding a prepreg obtained by impregnating the specific carbon fiber, a tubular body made of a composite material that is lightweight and has excellent strength such as torsional strength can be obtained. In addition, the prepreg has a feature that it is excellent in handleability such as winding around a mandrel.

The present invention will be described in detail below.

Examples of the carbon fibers used as the constituent element (A) in the present invention include acrylic, pitch and rayon carbon fibers. Of these, acrylic resins having high tensile strength are preferable. As the form of carbon fiber, carbon fiber obtained by twisting and firing precursor fiber, so-called twisted yarn, untwisted carbon fiber of the twisted yarn, so-called untwisted yarn, substantially twisted precursor fiber Untwisted yarns that are heat-treated without heat treatment can be used, but untwisted yarns or untwisted yarns are preferable in consideration of the balance between the moldability and strength characteristics of the composite material. Furthermore, handling properties such as good adhesion between the prepreg surfaces are good. From the viewpoint of the above, a non-twisted yarn is preferable. Also,
Graphite fibers may also be included in the carbon fibers in the present invention.

As the carbon fiber in the present invention, a carbon fiber having a high tensile elastic modulus is used so that a sports article such as a golf club shaft or a fishing rod can exhibit sufficient rigidity by using a small amount of the material. The tensile modulus of elasticity of such a carbon fiber is 330 to 100.
It is necessary to be 0 GPa, and preferably 350 to 800 GPa. If the tensile modulus is less than 330 GPa, it is difficult to develop sufficient rigidity in the material, which is not preferable. If it exceeds 1000 GPa, the strength of the carbon fiber becomes insufficient, which is not preferable.

The carbon fiber of the constituent element (A) in the present invention has a surface area ratio measured using an atomic force microscope.
It is necessary to be 1.00 to 1.10, and 1.00 to
1.05 is more preferable. The surface area ratio is the ratio of the actual surface area of the carbon fiber surface to the projected area and represents the degree of surface roughness. The closer the surface area ratio is to 1, the smoother the surface area is. Here, the actual surface area and the projected area can be measured using an atomic force microscope, for example, by the method described later. The projected area is the projected area on the secondary phase considering the curvature of the fiber cross-sectional area. Conventionally, when the carbon fiber is smooth, it has been considered that the adhesiveness between the matrix resin and the surface of the carbon fiber is reduced, and the strength of the resulting fiber-reinforced composite material is reduced, but as a result of intensive studies by the present inventors, In the case of a high elastic modulus type carbon fiber having a tensile elastic modulus of 330 GPa or more, it was surprisingly found that the smoother surface of the carbon fiber improves the strength of the tubular body made of the fiber-reinforced composite material. In particular, the present invention has been found to significantly improve the strength of a combination of the carbon fiber and a cured resin product having a specific compressive elastic modulus and compressive fracture strain. The surface area ratio is 1.00 when the carbon fibers have no irregularities on the surface, and the surface area ratio exceeding 1.10 is not preferable because the effect of improving the strength of the tubular body is not sufficient.

The acrylic carbon fiber which can be preferably used in the present invention can be produced, for example, through the steps described below.

A spinning dope containing polyacrylonitrile obtained from a monomer containing acrylonitrile as a main component is spun by a wet spinning method, a dry-wet spinning method, a dry spinning method, or a melt spinning method. The coagulated yarn after spinning is washed with water, drawn, dried, and subjected to a yarn-forming process such as application of an oil agent to produce an acrylic precursor, and the obtained acrylic precursor is subjected to flame resistance and carbonization to obtain an acrylic carbon fiber. be able to.

Here, as a spinning method, a wet spinning method or a dry-wet spinning method can be preferably adopted, and a dry-wet spinning method is more preferable in that a carbon fiber having a smooth carbon fiber surface can be easily obtained.

In the wet spinning method or the dry-wet spinning method, the surface roughness of the obtained carbon fiber can be controlled by appropriately optimizing the coagulation rate in the coagulation process after spinning and the draw ratio of the coagulated fiber. It is possible to do so, which is preferable.

Further, in the present invention, the component (A)
In addition to the carbon fiber, the reinforcing fiber such as glass fiber, aramid fiber, boron fiber, alumina fiber and silicon carbide fiber can be used in combination. Two or more kinds of these fibers may be mixed and used.

In the present invention, as the form of the carbon fiber, one in which the fiber directions are aligned in one direction or a woven fabric can be used. The woven fabric may be either plain weave or satin weave.

In order to reduce the weight of the fiber-reinforced composite material, the carbon fiber content in the prepreg is preferably high, and the carbon fiber content in the prepreg is preferably 70 to 90% by weight, more preferably. It is preferably 75 to 90% by weight, more preferably 80 to 90% by weight. If the carbon fiber content is less than 70% by weight, the weight-reducing effect may not be sufficient, and if the carbon fiber content exceeds 90% by weight, voids remain in the composite material due to the small amount of resin and The characteristics may deteriorate.

The epoxy resin composition of the constituent element (B) in the present invention contains an epoxy resin and a curing agent, and the resin composition obtained by heating and curing the constituent element (B) has a compression elastic modulus of 2. It is necessary that the strain is 0.3 to 3.4 GPa and the nominal strain at the time of compression failure is 50% or more.
These resin compression characteristics have a side length of 6 mm ± 0.2 m
For a test piece cut out from a resin cured product so as to be a cube of m, the test speed is 1 ± 0.2 mm / min, and other conditions are measured according to JIS K7181. The cured resin product used in the compression test is obtained by heat treatment for 90 minutes at a constant temperature selected from the range of 100 ° C to 200 ° C.

The resin composition obtained by heating and curing the epoxy resin composition which is the constituent (B) of the present invention has a compressive elastic modulus of 2.3 to 3 in order to exhibit excellent material strength.
4 GPa is required, 2.5-3.4 GP
It is preferable that it is a, and it is more preferable that it is 2.7-3.4 GPa. The compressive elastic modulus is 2.3 GPa
If it is less than 4, the yield strength against compressive stress is insufficient and the material strength becomes insufficient, and if it exceeds 3.4 GPa, the cured resin product becomes brittle, or the residual thermal stress in the material becomes large. It is not preferable because it causes a decrease in material strength.

Further, in addition to the compression elastic modulus, the nominal strain at the time of compression failure of the resin cured product obtained from the epoxy resin composition which is the constituent element (B) of the present invention must be 50% or more. , 55% or more, more preferably 60% or more. The present inventors set the compressive elastic modulus of the resin cured product to the above-mentioned range and, at the same time, to a high level range in which the nominal strain at the time of compressive fracture is applied, so that the direction of the fiber and the value exceeding 0 # and less than 90 # It is presumed that the strength under the compressive stress in the direction of forming a constant angle (hereinafter, referred to as the compressive strength in the non-fiber direction) can be improved, and the effect of the present invention is obtained. The higher the nominal strain at the time of compressive failure is, the more preferable, but 80% is sufficient for the use of the present invention.

The glass transition temperature of the resin cured product obtained by curing the constituent (B) of the present invention is preferably 80 to 120 ° C. It is more preferably 90 to 100 ° C, and most preferably 100 to 120 ° C. When the glass transition temperature of the resin cured product exceeds 120 ° C., the thermal stress remaining in the tubular body made of the fiber-reinforced composite material becomes large, and the strength characteristics thereof may deteriorate. If the glass transition temperature of the cured resin is less than 80 ° C., the resin softened by heat may cause clogging of the polishing machine when the surface is polished after being formed into a tubular body. The glass transition temperature of the resin cured product is a value measured by a differential scanning calorimetry (DSC), and is included in the tubular body by measuring a sample cut from the tubular body made of the fiber-reinforced composite material. The glass transition temperature of the cured resin can be measured.

Furthermore, regarding the resin cured product obtained by curing the constituent element (B) of the present invention, the compact tension method according to ASTM-E399 or ASTM5
The mode I fracture toughness value G _{IC at the} initial stage of crack propagation measured by the SENB method according to 045-91 is 2
00 J / m ² or more, preferably 400 J / m ²
The above is more preferable. Mode I of cured resin
When the fracture toughness value G _IC is 200 J / m ² or more, impact resistance and fatigue properties of the composite material tubular body can be improved.

Furthermore, it is preferable that the resin cured product obtained by curing the constituent element (B) of the present invention has a tensile elongation at break of 8% or more as measured according to JIS K7113. When the tensile elongation at break is 8% or more, the twisting strength and impact resistance of the composite material tubular body can be further improved.

Here, the G _IC and the tensile elongation at break of the resin cured product are 100 to 200 ° C. for the constituent element (B) of the present invention.
It is measured for a cured product obtained by performing a heat treatment for 90 minutes at a constant temperature selected from the range.

In the present invention, in order to exhibit the above-described resin compression characteristics, 75 to 100% by weight of a bifunctional epoxy resin is contained in 100% by weight of the epoxy resin contained in the component (B) in the present invention. Preferably.

Specific examples of the bifunctional epoxy resin include:
Obtained from bisphenol A type epoxy resin obtained from bisphenol A and hydrogenated product thereof, bisphenol F type epoxy resin obtained from bisphenol F and hydrogenated product thereof, bisphenol S type epoxy resin obtained from bisphenol S, and tetrabromobisphenol A Bisphenol type epoxy resin such as tetrabromobisphenol A type epoxy resin, bisphenol AD type epoxy resin obtained from bisphenol AD,
Resorcin diglycidyl ether, hydroquinone diglycidyl ether, 4,4'-dihydroxy-3,3 ', 5,5'-tetramethylbiphenyl diglycidyl ether, diglycidyl ether of 1,6-dihydroxynaphthalene, diglycidyl amine of aniline , Diglycidylamine of o-toluidine, diglycidyl ether of 9,9-bis (4-hydroxyphenyl) fluorene, isocyanate modified products of bisphenol A type epoxy resin, diglycidyl phthalate, diglycidyl terephthalate, hexahydro Phthalic acid diglycidyl ester, hexahydroterephthalic acid diglycidyl ester, dimer acid diglycidyl ester, 1,4-di-tert-butyl-2,5-bis (2,3-epoxypropoxy) -benzene, 2,2 '-Dimethyl-4,4'-dihydroxy-5,5'-di-tert-butyldiphenylsulf Oxidation product of the reaction product of chloromethyloxirane and 4,4'-methylenebis (2,6-dimethylphenol) and chloromethyloxirane, the compound having two double bonds in the molecule Examples of the polyepoxide obtained by

Further, in order to impart a high compressive elastic modulus without significantly reducing the nominal strain at the time of compressive failure of the cured resin product, a bisphenol F type epoxy resin, a diglycidyl ether of 1,6-dihydroxynaphthalene, and a diamine of aniline. Glycidyl amine, diglycidyl amine of o-toluidine, isocyanate modified product of bisphenol A type epoxy resin, phthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, hexahydroterephthalic acid diglycidyl ester At least one epoxy resin is used in an amount of 10 to 10 in 100% by weight of the total bifunctional epoxy resin.
0% by weight is preferable, and 20 to 100% by weight is preferable.
More preferably, it is included. If the compounding ratio is less than 10% by weight, the effect of improving the compression elastic modulus of the cured resin may not be sufficient.

Above all, it is preferable to contain a bisphenol F type epoxy resin or an isocyanate-modified epoxy resin. It is preferably 10 to 100% by weight, more preferably 20 to 100% by weight based on 100% by weight of the total bifunctional epoxy resin.
It is recommended to include 90% by weight. By including the bisphenol F type epoxy resin in the present invention, the balance of properties such as viscoelasticity of the uncured resin composition, tensile fracture elongation of the resin cured product, toughness, plastic deformability, elastic modulus, heat resistance, etc. It is preferable because an excellent prepreg can be obtained. Especially, the epoxy equivalent which tends to be high viscosity is 750 or more 2
When the functional epoxy resin is included, it is preferable to include it in combination with the bisphenol F type epoxy resin. The bisphenol F type epoxy resin may have an epoxy equivalent of less than 750, or the bisphenol F type epoxy resin itself may have an epoxy equivalent of 750.
It may be more.

In the component (B) of the present invention, the epoxy equivalent is preferably 750 or more, more preferably 900.
More preferably, the difunctional epoxy resin of 1000 or more is contained in an amount of 5 to 50 in 100% by weight of the total epoxy resin.
It is preferable to include it by weight%. Epoxy equivalent is 750
If it is less than the above range, the cured resin may not exhibit a nominal strain at the time of sufficient compression failure. Epoxy equivalent of 750 or more 2
By adding an appropriate amount of the functional epoxy resin, it is possible to impart a higher degree of nominal strain at the time of compressive fracture to the resin cured product and improve the compressive strength in the non-fiber direction, but the compounding ratio is 5% by weight. If it is less than 50% by weight, the effect may not be sufficient, and if it exceeds 50% by weight, the viscosity of the uncured resin composition becomes too high, impregnation into reinforcing fibers, adhesion between prepregs, and flexibility of prepreg. It may impair the handling properties such as sex.

The fact that the prepreg contains the bifunctional epoxy resin having an epoxy equivalent of 750 or more in such a mixing ratio means that the uncured epoxy resin composition is extracted from the prepreg with an organic solvent such as chloroform. , GPC, reverse phase chromatography, infrared absorption, ¹ H NMR, ¹³ C NMR for the extracted components,
It can be specified by performing a combination of methods such as mass spectrometry.

In the epoxy resin composition of the present invention, in order to improve the heat resistance and the compression elastic modulus of the obtained carbon fiber reinforced composite material, the resin strain of the resin cured product is not significantly impaired in the nominal strain at the time of compression failure. A polyfunctional epoxy resin having more than two epoxy groups in the molecule may be included.

The polyfunctional epoxy resin is not particularly limited, but triglycidyl ether of tris (p-hydroxyphenyl) methane and its derivative, tetrakis (p-
Hydroxyphenyl) ethane tetraglycidyl ether and its derivatives, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether, novolak glycidyl esters, tetraglycidyldiaminodiphenylmethane, tetraglycidyl esters obtained from phenol derivatives such as phenol and alkylphenols and halogenated phenols. Glycidyl m-xylylenediamine,
Triglycidyl-m-aminophenol, triglycidyl-
Examples thereof include p-aminophenol and triglycidyl isocyanurate.

Further, as the epoxy resin used as the constituent element (B), it is also preferable to include an imide skeleton-containing monofunctional epoxy resin such as N-glycidylphthalimide in order to improve the compression elastic modulus of the resin cured product.

Examples of the curing agent in the present invention include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine and m-xylylenediamine. Aromatic amines with active hydrogen, diethylenetriamine, triethylenetetramine, isophoronediamine, bis (aminomethyl) norbornane, bis (4-aminocyclohexyl) methane, aliphatic amines with active hydrogen such as dimer acid esters of polyethyleneimine, Modified amines obtained by reacting these active hydrogen-containing amines with epoxy compounds, acrylonitrile, phenol and formaldehyde, thiourea and other compounds, dimethylaniline, dimethylbenzylamine, 2,4,6-tris (dimethylaminomethyl) Phenol and 1- Tertiary amines having no active hydrogen such as substituted imidazole, dicyandiamide, tetramethylguanidine, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and carvone such as methylnadic acid anhydride. Acid anhydrides, polycarboxylic acid hydrazides such as adipic acid hydrazide and naphthalene dicarboxylic acid hydrazide, polyphenol compounds such as novolac resins, polymercaptans such as esters of thioglycolic acid and polyols, Lewis such as boron trifluoride ethylamine complex Examples thereof include acid complexes and aromatic sulfonium salts.

These hardening agents may be combined with a suitable hardening aid to enhance the hardening activity. A preferred example is dicyandiamide containing 3-phenyl-1,
1-dimethylurea, 3- (3,4-dichlorophenyl) -1,
1-dimethylurea (DCMU), 3- (3-chloro-4-
Examples of combining urea derivatives such as methylphenyl) -1,1-dimethylurea and 2,4-bis (3,3-dimethylureido) toluene as curing aids, carboxylic acid anhydrides and novolac resins with tertiary amines. Examples of combining the above as a curing aid are given.

In the epoxy resin composition of the present invention,
In addition to the epoxy resin and the curing agent, a low molecular weight organic compound,
Other components such as oligomers, polymeric compounds, organic or inorganic particles can be included.

As the low molecular weight organic compound which can be blended in the constituent element (B) of the present invention, a hydrogen bonding functional group such as an amide group, a urethane group, an imide group or a sulfonamide group is contained in the molecule, and the constituent element (B). Examples of the compound include a compound having a functional group that reacts with the epoxy resin or the curing agent contained in, and by mixing these, it is possible to increase the compression elastic modulus without significantly impairing the compression fracture strain of the cured resin product. .

As examples of such low molecular weight organic compounds, acrylamide derivatives such as acrylamide, N, N'-dimethylacrylamide and acryloylmorpholine are preferably used.

As the oligomer which can be blended in the constituent element (B) of the present invention, a polyester polyurethane having a polyester skeleton and a polyurethane skeleton, a urethane skeleton having a polyester skeleton and a polyurethane skeleton, and a urethane having a (meth) acrylate group at the terminal of the molecular chain are used. Examples thereof include (meth) acrylate and indene-based oligomer.
Here, in the polyester polyurethane, when the epoxy resin composition is cured, the ester group in the molecular chain thereof reacts with the curing agent, particularly the curing agent having active hydrogen such as an amino group.

A thermoplastic resin is preferably used as the polymer compound which can be incorporated in the constituent element (B) of the present invention.
By blending the thermoplastic resin, the effect of controlling the viscosity of the resin, controlling the handleability of the prepreg, or improving the adhesiveness is enhanced, which is preferable.

Examples of thermoplastic resins that can be suitably used in the present invention include polyvinyl acetal resins such as polyvinyl formal and polyvinyl butyral, polyvinyl alcohol, phenoxy resin, and thermoplastic resins having an amide bond, such as polyamide and polyimide. Examples of the thermoplastic resin having a sulfonyl group include polysulfone. Polyamide, polyimide and polysulfone may have a functional group such as an ether bond or a carbonyl group in the main chain. The polyamide may have a substituent on the nitrogen atom of the amide group.

When the thermoplastic resin is contained, the addition of 1 to 20 parts by weight of the thermoplastic resin to 100 parts by weight of the epoxy resin imparts appropriate viscoelasticity to the epoxy resin composition and provides a good composite material. It is preferable in that physical properties can be obtained.

Regarding the viscoelasticity of the component (B) epoxy resin composition which is present by being impregnated with carbon fibers in the prepreg of the present invention, the measurement frequency is 0.5 Hz and 50 ° C. in order to obtain good handling properties of the prepreg. It is preferable that the storage elastic modulus G'in the above is 300 to 50,000 Pa. If G'is less than 300 Pa, the adhesive strength between the prepreg surfaces (hereinafter referred to as the adhesive strength of the prepreg) is weak, and in the prepreg laminating step, the laminated prepregs are immediately peeled off to hinder the laminating work. It may come. Further, when G'exceeds 50000 Pa, the flexibility of the prepreg may be deteriorated, the shapeability on the curved surface may not be sufficient, and the impregnating property into the reinforcing fiber may be deteriorated. Such viscoelasticity is due to the component (B)
It is achieved by optimizing the type and mixing ratio of the epoxy resin component contained in, or by adding an appropriate amount of the thermoplastic resin.

The prepreg of the present invention has an adhesive strength of 0.05 to 0.15 N / m, which is measured under the conditions described below, in order to produce a tubular body made of a fiber-reinforced composite material.
It is preferably m ² . If the adhesive strength of the prepreg is less than 0.05 N / mm ² , the prepregs stacked in the prepreg laminating step may be immediately peeled off, which may hinder the laminating operation. Also, 0.15 N / m
If it exceeds m ² , it may be difficult to correct the prepreg when it is attached. When a tubular body is laminated using a prepreg that does not have such a preferable adhesive strength, defects such as disorder of fiber orientation are likely to occur inside the tubular body, but especially a fiber-reinforced composite material to which a reinforcing fiber having a high elastic modulus is applied is used. In the case of a tubular body, it is susceptible to strength reduction due to such defects.

Therefore, the tensile elastic modulus is 330 to 100.
In the case of the prepreg of the present invention to which 0 GPa carbon fiber is applied, the adhesive strength is preferably 0.05 to 0.15 N / mm ² .

If a cover film or the like is not attached to the surface of the prepreg and the surface of the prepreg is left exposed to the atmosphere, the adhesive strength of the prepreg may decrease with time. Not only immediately after peeling off the cover film or release paper attached to the prepreg surface, but also under the condition that the prepreg surface is exposed to the atmosphere at 24 ° C. and relative humidity of 50% RH.
Even after being left for 4 hours, the prepreg adhesive strength is still 0.
From the standpoint of work efficiency, it is preferably from 05 to 0.15 N / mm ² . In order to obtain such preferable prepreg adhesive strength, the surface area ratio measured by an atomic force microscope is
It is effective to use carbon fibers in the range of 1.00 to 1.10.

Further, in order to obtain the adhesive strength of such a prepreg, it is effective to control the viscoelasticity of the epoxy resin composition present in the prepreg within an appropriate range as described above. It is more preferable to control the amount of the epoxy resin composition (hereinafter, referred to as the amount of surface resin) present in 1., and the greater the amount of surface resin, the more the adhesive strength of the prepreg can be improved. The amount of surface resin can be controlled by adjusting conditions such as the impregnation pressure, the tension applied to the reinforcing fibers, and the temperature at which the epoxy resin composition is heated in the step of impregnating the carbon fiber with the epoxy resin composition.

The carbon fiber which is the constituent element (A) of the present invention enhances the adhesiveness of the epoxy resin composition to the resin cured product, and further enhances the non-fiber compressive strength of the carbon fiber reinforced composite material. In order to do so, on the surface of the carbon fiber, epoxy group, hydroxyl group, acrylate group, methacrylate group,
A compound having at least one functional group selected from a carboxyl group and a carboxylic acid anhydride group is preferably attached as a sizing agent. By attaching a compound having these functional groups as a sizing agent to the surface of the carbon fiber in advance, a chemical bond or a hydrogen bond between the functional group on the carbon fiber surface and the functional group in the polymer network of the resin cured product. By the non-covalent bond of the above, the adhesiveness between the carbon fiber and the resin cured product can be enhanced.

Further, as such a sizing agent, in order to enhance the adhesiveness between the carbon fiber and the cured resin, and when water is used as a solvent in the step of attaching the sizing agent to the carbon fiber described later, it is easy to handle. It is preferably water-soluble from the viewpoint of

As a method for producing the carbon fiber to which the sizing agent is attached, for example, the carbon fiber is caused to pass through a sizing solution in which the sizing agent is dissolved or dispersed so as to be attached to the surface of the carbon fiber, and then heated. There is a method of removing the solvent.

Examples of the compound having an epoxy group which can be contained in the sizing agent in the present invention include a bisphenol A type epoxy resin obtained from bisphenol A and a hydrogenated product thereof, and a bisphenol F type epoxy resin obtained from bisphenol F. And hydrogenated products thereof, bisphenol S type epoxy resins obtained from bisphenol S, tetrabromobisphenol A type epoxy resins such as tetrabromobisphenol A, bisphenol A
Bisphenol AD type epoxy resin obtained from D, resorcin diglycidyl ether, hydroquinone diglycidyl ether, 4,4'-dihydroxy-3,3 ', 5,5'-tetramethylbiphenyl diglycidyl ether, 1,6-dihydroxynaphthalene Diglycidyl ether, aniline diglycidyl amine, o-toluidine diglycidyl amine,
Diglycidyl ether of 9,9-bis (4-hydroxyphenyl) fluorene, isocyanate modified product of bisphenol A type epoxy resin, phthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, hexahydroterephthalate Acid diglycidyl ester, dimer acid diglycidyl ester, 1,4-di-tert-butyl-2,5-bis (2,3-epoxypropoxy) -benzene, 2,2'-dimethyl-4,4'-dihydroxy -5,5'-di-tert-butyldiphenyl sulfide reaction product with chloromethyloxirane, 4,4'-methylenebis (2,6-dimethylphenol) reaction product with chloromethyloxirane, in the molecule Triglycidyl tris (p-hydroxyphenyl) methane, a polyepoxide obtained by oxidizing a compound having two double bonds Ether and its derivatives, tetrakis (p-hydroxyphenyl)
Tetraglycidyl ether of ethane and its derivatives,
Triglycidyl ether of glycerin, tetraglycidyl ether of pentaerythritol, glycidyl ester of novolac obtained from phenol derivatives such as phenol and alkylphenol, halogenated phenol,
Examples thereof include tetraglycidyl diaminodiphenylmethane, tetraglycidyl m-xylylenediamine, triglycidyl-m-aminophenol, triglycidyl-p-aminophenol, and triglycidyl isocyanurate.

Examples of the compound having a hydroxyl group which can be contained in the sizing agent in the present invention include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol and dipropylene. Glycol, polypropylene glycol, 2-methyl-1,3-propanediol, 1,3
-Butanediol, neopentyl glycol, hydrogenated bisphenol A, 1,4-butanediol, an adduct of bisphenol A and propylene oxide or ethylene oxide, 1,2,3,4-tetrahydroxybutane , Glycerin, trimethylolpropane, 1,3-propanediol, 1,2-cyclohexane glycol, 1,3
-Cyclohexane glycol, 1,4-cyclohexane glycol, 1,4-cyclohexane dimethanol, paraxylene glycol, bicyclohexyl-4,4'-
Examples thereof include aliphatic alcohols such as diol, 2,6-decalin glycol and 2,7-decalin glycol, and adducts of these propylene oxide or ethylene oxide.

Examples of the compound having an acrylate group or a methacrylate group that can be contained in the sizing agent in the present invention include acrylic acid ester, methacrylic acid ester, etc .; methyl (meth) acrylate, ethyl (meth) acrylate, N-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
Lauryl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, stearyl (meth) acrylate, tridecyl (meth) acrylate,
Dicyclopentenyloxyethyl (meth) acrylate,
Ethylene glycol monomethyl ether (meth) acrylate, ethylene glycol monoethyl ether (meth) acrylate, ethylene glycol monobutyl ether (meth) acrylate, ethylene glycol monohexyl ether (meth) acrylate, ethylene glycol mono-2-ethylhexyl ether (meth) acrylate, Diethylene glycol monomethyl ether (meth) acrylate, diethylene glycol monoethyl ether (meth) acrylate, diethylene glycol monobutyl ether (meth) acrylate, diethylene glycol monohexyl ether (meth) acrylate,
Diethylene glycol mono-2-ethylhexyl ether (meth) acrylate, dipropylene glycol monomethyl ether (meth) acrylate, dipropylene glycol monoethyl ether (meth) acrylate, dipropylene glycol monobutyl ether (meth) acrylate, dipropylene glycol monohexyl ether (meth ) Acrylate, dipropylene glycol mono 2
-Ethylhexyl ether (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, PTMG dimetacrylate, 1,3-butylene glycol di (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, 2-hydroxy-1,3 dimethacryloxypropane, 2,2-bis [4- (methacryloxyethoxy) phenyl] propane, 2,2-bis Examples thereof include compounds having an acrylate group or a methacrylate group in the molecule such as [4- (methacryloxydiethoxy) phenyl] propane, polyester (meth) acrylate, urethane (meth) acrylate, and epoxy (meth) acrylate.

Examples of the compound having a carboxyl group or a carboxylic acid anhydride group which can be contained in the sizing agent in the present invention include dodecenylsuccinic acid, polyadipic acid, polyazelaic acid, polysebacic acid, phthalic acid, methyltetrahydrophthalic acid. , Methylhyxahydrophthalic acid, methylhymic acid, hexahydrophthalic acid, tetrahydrophthalic acid, trimellitic acid, pyromellitic acid and their acid anhydrides.

The tubular body made of the fiber-reinforced composite material of the present invention contains a resin cured product obtained by heating and curing the above-mentioned constituent element (B) and the constituent element (A). (A) The surface area ratio measured by an atomic force microscope is 1.
00 to 1.10 and a tensile elastic modulus of 330 to 10
Carbon fiber of 00 GPa If this requirement is satisfied, the manufacturing method thereof is not particularly limited, but it is preferable to heat-cure and mold the above-mentioned prepreg because a tubular body made of a fiber-reinforced composite material can be obtained easily and with good quality.

In the fiber-reinforced composite material tubular body of the present invention, the constituent elements (A) are aligned in one direction,
In addition, it is preferable that at least one layer in which the fiber direction of the constituent element (A) is arranged at an angle of 20 ° to 90 # with respect to the longitudinal direction of the tubular body is included in the internal structure. By arranging carbon fibers having a tensile elastic modulus of 330 to 1000 GPa such that they are arranged at such an angle as the constituent element (A), it is possible to effectively increase the torsional rigidity of the lightweight tubular body.

In particular, when the tubular body of the present invention is applied to a golf shaft, the weight of the shaft can be reduced while maintaining the torsional rigidity and the torsional strength within appropriate ranges. It is particularly preferred that they are arranged.

Hereinafter, a method for producing a prepreg which can be suitably applied in the present invention, and a method for obtaining a carbon fiber reinforced composite material by laminating the prepregs and curing them by heating will be described.

The prepreg of the present invention is produced, for example, by a method such as a wet method in which a matrix resin is dissolved in a solvent such as methyl ethyl ketone or methanol to have a low viscosity and impregnated, or a hot melt method in which a viscosity is reduced by heating and impregnated. be able to.

In the wet method, the prepreg can be obtained by immersing the carbon fiber in a liquid containing a matrix resin, pulling it up, and evaporating the solvent using an oven or the like.

In the hot melt method, a method of impregnating carbon fibers directly with a matrix resin whose viscosity has been lowered by heating, or a film in which an epoxy resin composition is once coated on release paper is first prepared, and then the carbon fibers A resin-impregnated prepreg can be produced by stacking the films from both sides or one side and applying heat and pressure. The hot melt method is preferable because there is no solvent remaining in the prepreg.

In the prepreg of the present invention, the epoxy resin composition does not necessarily have to be impregnated to the inside of the carbon fiber bundle, and the carbon fibers aligned in one direction in a sheet shape or the epoxy resin near the surface of the carbon fiber woven fabric are not used. The resin composition may be localized.

In order to form a tubular body using the prepreg of the present invention, a method of laminating the prepreg and then heating and curing the resin while applying pressure to the laminate can be used.

The method of applying heat and pressure includes a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, an internal pressure molding method and the like. Especially for sports goods, the wrapping tape method and the internal pressure molding method are used. It is preferably adopted.

The wrapping tape method is a method of forming a tubular body by winding a prepreg around a core metal such as a mandrel, and is suitable for producing a rod-shaped body such as a golf club shaft or a fishing rod. Specifically, a prepreg is wound around a mandrel, a wrapping tape made of a thermoplastic resin film is wound around the outside of the prepreg for fixing and applying pressure to the prepreg, and the resin is heated and cured in an oven, and then a core metal is applied. A tubular body can be obtained by pulling out.

In the internal pressure molding method, a preform in which a prepreg is wound around an internal pressure imparting body such as a thermoplastic resin tube is set in a mold, and then high-pressure gas is introduced into the internal pressure imparting body to apply pressure. At the same time, the tubular body can be formed by heating the mold.

The fiber-reinforced composite material of the present invention can be produced by using the above-mentioned resin composition by a method which does not pass through a prepreg.

As such a method, for example, the component (A) is directly impregnated with the epoxy resin composition which is the component (B) of the present invention, followed by heating and curing, that is, the hand lay-up method. The filament winding method, the pultrusion method, the reaction injection molding method, the resin transfer molding method, etc. can be used. Among these methods, a method of preparing an epoxy resin composition by mixing two liquids of an epoxy resin contained in the constituent element (B) and a curing agent immediately before use can be preferably adopted.

[0078]

EXAMPLES The present invention will be described in detail below with reference to examples. It is an index of compression test of cured resin, measurement of glass transition temperature (hereinafter referred to as Tg) of cured resin, measurement of surface area ratio of carbon fiber, preparation of prepreg, adhesiveness of prepreg, compression strength in non-fiber direction. 6 # compressive strength of composite material,
Preparation of a tubular body made of a carbon fiber reinforced composite material and measurement of the torsional strength of the tubular body were carried out by the following methods. (1) Compression test of cured resin product The resin composition raw materials shown in Tables 1 and 2 were kneaded with a kneader to obtain a resin composition in which polyvinyl formal was uniformly dissolved. The obtained resin composition was heated to 80 ° C., defoamed with a vacuum pump, and then poured into a mold to obtain 130 ° C. (Examples 1 to 6, Comparative Examples 1 to 4) or 180 ° C. (Comparative Example 5).
By heat-treating for 90 minutes, a plate of 6 mm-thick resin cured product was prepared. Then, a cubic test piece having a side length of 6 mm was cut out from the cured resin plate, the test speed was 1 ± 0.2 mm / min, and other conditions were JIS K718.
The compressive elastic modulus and the nominal strain at the time of compressive failure were measured under the conditions according to 1. (2) Measurement of glass transition temperature (Tg) of cured epoxy resin For a measurement sample obtained by cutting out from a tubular body,
It was measured by the DSC method according to JIS K7112. During the DSC measurement, the heating rate was 40 ° C./minute. (3) Surface area ratio measurement of carbon fiber The carbon fiber to be used for measurement is fixed on the sample stand, and the Digital Inst
An image of a three-dimensional surface shape is obtained using the Ruments NanoScope III under the following conditions.・ Probe: Si cantilever integrated probe (OMCL-AC120TS manufactured by Olympus Optical Co., Ltd.) ・ Measuring environment: room temperature (20 ° C to 30 ° C) in atmosphere ・ Observation mode: tapping mode ・ Scanning speed: 0.3 to 0. 4 Hz ・ Scanning range: 2.5 μm × 2.5 μm ・ Number of pixels: 512 × 512 For the entire image obtained, the software (NanoScope III version 4.22r2, primary Flatten)
Data is processed using a filter, a Lowpass filter, and a third-order Plane Fit filter) to calculate the actual surface area and projected area. The projected area was calculated by calculating the projected area on the quadric surface approximated in consideration of the curvature of the fiber cross-sectional area, and the surface area ratio was calculated by the following formula. Surface area ratio = actual surface area / projected area The same measurement was performed twice, and the average value was taken as the surface area ratio of the carbon fiber. (4) Strand Tensile Elastic Modulus / Strength Measurement of Carbon Fiber According to the method described in JIS R7601, a carbon fiber bundle is impregnated with a resin having the following composition, and the resin is heat-cured at 130 ° C. for 35 minutes to perform a tensile test. A piece was prepared and the tensile strength and the tensile elastic modulus were measured. Resin composition: 3,4-epoxycyclohexylmethyl-
3,4-Epoxy-cyclohexane-carboxylate (100 parts by weight) / 3 Boron fluoride monoethylamine (3 parts by weight) / acetone (4 parts by weight) (5) Preparation of prepreg (a) Shown in Table 1 and Table 2. The raw material of the resin composition was kneaded with a kneader to obtain an epoxy resin composition in which polyvinyl formal was uniformly melted. (B) The obtained resin composition was applied onto release paper using a reverse roll coater to prepare a resin film having a resin areal weight of 20 g / m ² . Next, two resin films were superposed from both sides of the carbon fibers on the carbon fibers arranged in one direction in a sheet shape, sandwiched between metal rolls heated to 100 ° C., and heated and pressed to impregnate the resin composition. The carbon fibers used in each example are shown in Tables 1 and 2.

After impregnation, the release paper on one side is peeled off from the prepreg, a polyethylene film is attached to the surface of the peeled side, and the release paper is placed on one side and the polyethylene film is wound on the other side. As a result, the carbon fiber areal weight is 125 g / m ² , and the carbon fiber content is 76% by weight.
I got a prepreg. (6) Measurement of adhesive strength of prepreg By following the steps (a) and (b), 24 ° C. and relative humidity 50.
The adhesive strength of the prepreg was measured under the environment of% RH. (A) The prepreg used for measurement is 100 mm × 200 m
The prepreg A was cut into a size of m and firmly attached to a plastic plate having a flat surface with a double-sided tape. (B) On the surface of the prepreg A, a prepreg B cut from the same prepreg A and having a contact area of 10
44N so that mm × 10 mm (= 100 mm ² )
After pressing for 1 second with the load of, prepreg B is 30mm
The peeling force at the time of peeling in the direction perpendicular to the surface of the prepreg A at a speed of / min was measured, and this was measured as
The value divided by 0 mm ² ) was taken as the adhesive strength of the prepreg. (C) The measurement was performed within 10 minutes after the polyethylene film was peeled off and under two conditions after leaving the polyethylene film peeled off and exposing the surface at room temperature of 23 ° C. and 50% relative humidity for 24 hours. (7) The 6 # compressive strength unidirectional prepreg sheet of the composite material is laminated so that the direction of the fibers is the same and the thickness of the laminated plate is approximately 1 mm, and the prepreg sheet is laminated at a temperature of 13 in an autoclave.
0 ° C (Examples 1 to 6, Comparative Examples 1 to 4) or 180 ° C
(Comparative Example 5), a unidirectional composite material was produced by heating and pressing at a pressure of 290 Pa for 2 hours to cure. The obtained unidirectional composite material was cut out so that the angle of the reinforcing fibers was 6 °, and J
It was measured according to the IS-K-7076 method.

Unidirectional material thickness, fiber basis weight, fiber density,
The fiber volume content (Vf) was calculated from the number of laminated plies, and the obtained 6 ° compression strength was converted into a value when the volume content of the reinforcing fiber was 60%. (8) Preparation of tubular body made of carbon fiber reinforced composite material By the following operations (a) to (e), a laminated structure of [0 ₃ / ± 45 ₃ ] with respect to the cylinder axis direction and an inner diameter of 10 mm A tubular body made of a fiber-reinforced composite material was produced. A round rod made of stainless steel having a diameter of 10 mm (length 1000 mm) was used for the mandrel. (A) Two pieces of the unidirectional prepreg obtained in (5) above were cut into a rectangle having a length of 800 mm and a width of 106 mm so that the fiber direction was 45 degrees with respect to the axial direction of the mandrel. 1 so that the fiber directions cross each other
6 mm (corresponding to half the circumference of the mandrel) was offset and then laminated. (B) The laminated prepreg was wound around a release-treated mandrel so that the longitudinal direction of the prepreg and the axial direction of the mandrel were aligned. (Bias material) (c) The tensile modulus of elasticity of the carbon fiber is 295 GPa,
Carbon fiber basis weight 125 g / m ² , carbon fiber content 76%
Toray Co., Ltd.'s prepreg P2255F-12R with a length of 800 mm × width 1 so that the fibers are oriented in the longitudinal direction.
The 18 mm rectangular piece was wound so that the longitudinal direction of the prepreg and the axial direction of the mandrel were aligned.
(Straight material) (d) Wrap a wrapping tape (heat resistant film tape), and 130 ° C. in a curing oven (Examples 1 to 6 and Comparative Example 1).
~ 4) or 180 ° C (Comparative Example 5), and heat-molded for 90 minutes. (E) After molding, the mandrel was pulled out and the wrapping tape was removed to obtain a tubular body. (9) Measurement of torsional strength of tubular body A 400 mm-long test piece was cut out from a tubular body having an inner diameter of 10 mm, and "certification standard and standard confirmation method for golf club shaft" (edited by Product Safety Association, commonly known as Minister of Industry 5 No. 2087, 1993), and the torsion test was performed. The gauge length of the test piece was 300 mm, and 50 mm at both ends of the test piece was held by a fixing jig. The twist strength was calculated by the following formula. The measurement was performed in an environment of 23 ° C. and a relative humidity of 50% RH.

Torsional strength (N · m · deg) = breaking torque (N ·
m) × torsion angle at break (deg) (Examples 1 to 6, Comparative Examples 1 to 4) The raw materials shown in Tables 1 and 2 were mixed with a kneader to prepare an epoxy resin composition in which polyvinyl formal was uniformly dissolved. Obtained.

Using this resin composition and the carbon fibers shown in Tables 1 and 2, a sheet-like prepreg was produced according to the method described above.

Using this prepreg, a fiber-reinforced composite material and a fiber-reinforced composite material-made tubular body were produced, and the 6 ° compressive strength of the fiber-reinforced composite material was measured.

Further, the twist strength of the tubular body made of the fiber-reinforced composite material was measured according to the above method.

The physical properties of the cured resin product, the physical properties of the fiber reinforced composite material, and the physical properties of the fiber reinforced composite material tubular body of each example are summarized in Tables 1 and 2.

As can be seen from Table 1, the composite material obtained by molding the prepreg using the resin composition of the present invention has a high 6 ° compressive strength, which is an index of the compressive strength in the non-fiber direction. Further, it is understood that the tubular body formed by using the prepreg exhibits high torsional strength.

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[Table 1]

[0088]

[Table 2]

[0089]

The prepreg of the present invention has excellent handleability, and the fiber-reinforced composite material obtained by curing the prepreg has excellent material strength, especially in compressive stress from a direction at an angle to the fiber direction. It exhibits excellent strength even against. Further, the tubular body molded from the prepreg of the present invention has excellent torsional strength, and as a result, a tubular body having a predetermined strength can be obtained while achieving weight reduction.

The tubular body made of the fiber-reinforced composite material of the present invention is preferably used for golf club shafts, fishing rods, bicycle frames, badminton racket shafts, bicycle frame / handles, wheelchair frames, hockey sticks and the like. You can

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Claims (9)

[Claims] 1. A resin cured product containing the following constituents (A) and (B) and obtained by heating and curing the constituent (B) has a compressive elastic modulus of 2.3 to 3.4 GPa and a compression failure. A prepreg characterized by a nominal strain of 50% or more. (A) The surface area ratio measured by an atomic force microscope is 1.
00 to 1.10 and a tensile elastic modulus of 330 to 10
Epoxy resin composition containing carbon fiber (B) epoxy resin of 00 GPa and curing agent 2. The prepreg according to claim 1, wherein the bifunctional epoxy resin is contained in an amount of 75 to 100% by weight in 100% by weight of the epoxy resin. 3. In 100% by weight of a bifunctional epoxy resin,
The prepreg according to claim 1 or 2, which comprises 5 to 100% by weight of a bisphenol F type epoxy resin or an isocyanate modified epoxy resin. 4. 5 to 5 bifunctional epoxy resins having an epoxy equivalent of 750 or more in 100% by weight of the epoxy resin.
The prepreg according to claim 1, wherein the prepreg contains 0% by weight. 5. The adhesive strength between the prepreg surfaces is 0.05.
~ 0.15N / mm ²2. The method according to claim 1, wherein
The prepreg according to any one of to 4. 6. An epoxy group, a hydroxyl group,
Acrylate group, methacrylate group, carboxyl group,
The prepreg according to any one of claims 1 to 5, wherein a compound having at least one functional group selected from carboxylic acid anhydride groups is attached as a sizing agent. 7. A fiber-reinforced composite material tubular body comprising a layer formed by heat-curing the prepreg according to any one of claims 1 to 6. 8. A fiber-reinforced composite material tubular body comprising a resin cured product obtained by heating and curing the constituent element (B) and the constituent element (A). (A) The surface area ratio measured by an atomic force microscope is 1.
00 to 1.10 and a tensile elastic modulus of 330 to 10
Epoxy resin composition containing carbon fiber (B) epoxy resin of 00 GPa and curing agent 9. The component (A) is aligned in one direction, and the component (A) has an internal structure.
Fiber orientation of 20 ° to 90 # with respect to the longitudinal direction of the tubular body
The fiber-reinforced composite material tubular body according to claim 7 or 8, wherein the tubular body is made of a fiber-reinforced composite material.