JP2003147102A - Prepreg and tubular body made of fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a prepreg for furnishing a light-weight tubular body made of a fiber-reinforced composite material excellent in strength properties such as torsional strength and rigidity, and to provide a tubular body thereof. SOLUTION: This prepreg comprises (A) a carbon fiber, (B) an epoxy resin having 75-100 wt.% of a bifunctional epoxy resin, and (C) a curing agent, wherein the tensile strength Y (N/bundle) of a bundle of yarns of constituent (A), the strength Y being converted to a value based on 12,000 single yarns, and the strand tensile modulus X (GPa) have the relationship: Y>=-4X/3+1,070, or the tensile strength Y (N/bundle) is >=550 N/bundle, and the strand tensile modulus X is in the range of 320-600 GPa. A tubular body is made of the fiber- reinforced composite material by comprising layers formed by thermally curing the prepreg.

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 A fiber-reinforced composite material composed of carbon fiber and a matrix resin is widely used for sports applications, aerospace applications, and general industrial applications because of its excellent mechanical strength characteristics. Particularly in sports applications, shafts for golf clubs, fishing rods, rackets such as tennis and badminton, and sticks such as hockey can be mentioned as important applications.

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 fibers are impregnated with a matrix resin is widely used. In this method, a high-performance fiber-reinforced composite material tubular body is obtained by laminating a plurality of prepregs and then heating them.

The weight reduction is particularly required for the tubular body made of the fiber-reinforced composite material for sports, that is, the shaft for golf club, the fishing rod and the like. In order to reduce the weight of a fiber-reinforced composite material tubular body while maintaining its rigidity within an appropriate range, it is effective to apply a fiber having a high elastic modulus as the reinforcing fiber and to increase the fiber content. ,
Carbon fiber is often used. Conventionally, tensile elastic modulus 230G
Many prepregs using carbon fibers in a so-called standard elastic modulus region of about Pa and a so-called medium elastic modulus region of about 290 GPa are used, but the rigidity as a shaft and the feeling when shaken while being further reduced in weight. In recent years, in order to obtain a proper value, it has been required to apply a prepreg using a carbon fiber having a tensile elastic modulus of 320 GPa or more, further 370 GPa or more and a higher elastic modulus region. However, in general, when the carbon fiber in the high elastic modulus region is used, the strength such as the torsional strength of the tubular body is insufficient as compared with the case where the carbon fiber in the standard elastic modulus region or the medium elastic modulus region is used. There are many cases, and it is difficult to reduce the weight due to its application.

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 320 GPa or more, its effect has not been sufficient.

[0006]

The object of the present invention is to solve the problems of the prior art, to obtain a fiber reinforced composite material having excellent strength characteristics, and to further improve the handling property of the prepreg, and The present invention provides a tubular body made of a fiber-reinforced composite material obtained by using such a prepreg.

[0007]

In order to achieve the above object, the present invention has the following constitution. That is, the tensile strength Y of the fiber bundle that includes the following constituent elements (A), (B), and (C) and is equivalent to the number of single yarns of the constituent element (A) of 12000
(N / bundle) and strand tensile elastic modulus X (GPa) satisfy the following relationship: prepreg.

Y ≧ -4X / 3 + 1070 (A) In 100% by weight of the carbon fiber (B), the bifunctional epoxy resin is 75 to 1
Epoxy resin (C) curing agent contained in an amount of 00% by weight, or a fiber containing the following constituent elements (A), (B) and (C) and having a number of single yarns of constituent element (A) of 12000. The tensile strength Y (N / bundle) of the bundle is 550 N / bundle or more, and the strand tensile elastic modulus X is 320 GPa to 60.
Prepreg characterized by being in the range of 0 GPa. In (A) 100% by weight of carbon fiber (B), 75 to 1 of bifunctional epoxy resin
A fiber-reinforced composite material tubular body comprising an epoxy resin (C) curing agent contained in an amount of 00% by weight, and a layer formed by heating and curing the prepreg.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The essential points of the present invention are as follows, to prepare a prepreg in which a carbon fiber satisfying a bundle strength of a certain value or more and a specific epoxy resin composition are prepared, and the material is bias laminated and molded into a tubular body. As a result, they have found that the product is a tubular body that is surprisingly lightweight and exhibits excellent torsional strength.

Examples of the carbon fiber 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 the carbon fiber, twisted yarn, untwisted yarn, untwisted yarn, etc. can be used, but untwisted yarn or untwisted yarn is preferable in consideration of the balance between the moldability and strength characteristics of the composite material, and further, the adhesion between the prepreg surfaces. Untwisted yarns are preferable from the viewpoint of handleability such as property. Further, the carbon fiber in the present invention may also include graphite fiber.

Generally, the strength of carbon fiber is often compared and evaluated by the tensile strength of a strand obtained by impregnating a fiber bundle with a specific epoxy resin and then curing as described later. In the present invention, several kinds of carbon fibers are used. Comparing the torsional strengths of tubular bodies in which corresponding prepregs are bias-laminated, the torsional strengths of the tubular bodies are surprisingly different even when comparing carbon fibers having similar strand tensile strengths. I found out. As a result of diligent examination, the bundle strength of the carbon fibers used is an important factor that influences the torsional strength of the tubular body, and by combining such high bundle strength carbon fibers with a specific epoxy resin, the torsional strength of the tubular body can be improved. The inventors have found that a synergistic effect is produced and completed the present invention.

That is, generally, as the strand tensile elastic modulus increases, the bundle strength tends to decrease. However, by setting the bundle tensile strength to a certain value or more, the twist strength of the tubular body increases. It will improve.

That is, the component (A) used in the present invention
The carbon fiber of No. 1 has a tensile strength Y (N / bundle) (hereinafter, abbreviated as bundle strength Y) and a strand tensile elastic modulus X (GPa) of a fiber bundle in terms of the number of single yarns of 12,000, and the following relational expression Y ≧ -4X / 3 + 1070 or its bundle strength Y (N / bundle) is 550
N / bundle or more and strand tensile elastic modulus X is 32
It must be in the range of 0 GPa to 600 GPa.

The meaning of 12,000 single yarns is, for example, 4 times the measured value when the bundle strength of 3000 single yarns is measured, and 2 times the measured value when the bundle strength of 6000 single yarns is measured. In other words, it means that the bundle strength per 12000 yarns is converted (it does not mean that it is limited to a carbon fiber bundle having 12000 single yarns).

The above relational expression Y ≧ -4X / 3 + 1070
By using a carbon fiber that satisfies the above as a reinforcing material and forming a tubular body using a prepreg that is combined with a specific epoxy resin described later, while maintaining the conventional bending rigidity and strength without sacrificing the lightness, surprisingly A tubular body exhibiting excellent torsional strength can be obtained. Conversely, if the carbon fiber used does not satisfy the above relational expression, the torsional strength of the tubular body may be insufficient.

Further, it is preferable to satisfy the following relational expression from the viewpoint of improving the torsional strength.

Y ≧ -4X / 3 + 1170 In order to realize weight reduction of sports equipment such as golf club shafts and fishing rods and to obtain a suitable feeling, the strand tensile elasticity should be adjusted according to the design of the intended use. It is good to select a carbon fiber having an appropriate rate.

When strength is important, it is preferable to use carbon fiber having a strand tensile elastic modulus of 200 to 290 GPa. The prepreg using the carbon fiber in the standard elastic modulus region to the medium elastic modulus region has a higher strand tensile strength and compressive strength of the carbon fiber than the prepreg using the carbon fiber in the high elastic modulus region. The bending strength of the material tubular body is high. Moreover, the torsional strength is further improved by satisfying the above relational expression. Therefore,
For example, it is preferably used for golf club shafts for hard hitters, fishing rods for jigging, rock rods, and the like. It is also suitable for the tips of rods and the like that require flexibility and strength.

When a balance between strength and weight reduction is required, it is preferable to use carbon fiber having a strand tensile elastic modulus of 230 to 350 GPa. The prepreg using the carbon fiber having such a medium elastic modulus region exhibits appropriate bending strength and rigidity, and the torsional strength is also improved by satisfying the above expression, so that the weight can be further reduced. Therefore, for example, it is suitably used for a wood type golf club shaft, a fishing rod for a lure, and the like.

When it is particularly necessary to reduce the weight, it is preferable to use carbon fibers having a strand tensile elastic modulus of 320 GPa or more. Such a prepreg using carbon fibers having a medium to high elastic modulus region can exhibit sufficient rigidity by using a small amount of material. For this reason, long golf club shafts, women's
It is preferably used for golf club shafts for elderly people, ayu rods, and the like.

As described above, the bundle strength tends to decrease as the strand tensile elastic modulus of the carbon fiber increases. Further, when applying carbon fibers having a high elastic modulus for the purpose of weight reduction, it is necessary to obtain sufficient torsional strength with a small amount of prepreg. Therefore, in such a case, a certain level of bundle strength is required. That is, the bundle strength Y (N / bundle) of the carbon fiber of the constituent element (A) is 550 N / bundle or more, and the strand tensile elastic modulus X is 320 GPa to 600 GPa.
Must be within the range. Furthermore, 350-55
0 GPa is more preferable from the viewpoint of increasing rigidity and reducing weight. When the tensile modulus is less than 320 GPa, it is difficult to bring out sufficient rigidity in the material while sufficiently exerting the weight-reducing effect, and the tubular body obtained by bias-laminating the material is excessively deformed due to the torsional stress, which is preferable. Absent. If it exceeds 600 GPa, the compressive strength of the carbon fiber becomes insufficient, and the torsional strength of the tubular body in which the material is bias-laminated is significantly reduced, which is not preferable.

If the bundle strength is less than 550 N / bundle, the tubular body having the material bias-laminated may have insufficient twist strength. More preferably, the bundle strength is 600 N / bundle or more, and further, the bundle strength is preferably 650 N / bundle or more.

Further, the carbon fiber bundle strength Y and the strand tensile modulus X (GPa) of the constituent element (A) satisfy the following relational expression Y ≧ -4X / 3 + 1070, and the carbon fiber bundle strength Y (N / N / Bundle is 550
N / bundle or more and strand tensile elastic modulus X is 32
The range of 0 GPa to 600 GPa is particularly preferable.

The acrylic carbon fiber that 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 fibers, those in which the fiber directions are aligned in one direction and woven fabrics 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% by weight or more, more preferably 75%. It is preferable that the content is at least wt%, more preferably at least 80 wt%.

As the epoxy resin of the constituent element (B) in the present invention, a resin obtained by heat curing by adding 75 to 100% by weight of a bifunctional epoxy resin to 100% by weight of the constituent element (B). A cured product (hereinafter referred to as a resin cured product) exhibits sufficient tensile breaking elongation, toughness and plastic deformation ability, and imparts high strength characteristics to the fiber-reinforced composite material combined with the above-mentioned constituent element (A). it can. 7
If it is less than 5% by weight, the cured resin does not exhibit sufficient tensile elongation at break, toughness and plastic deformation ability, and the torsional strength of the tubular body molded using the prepreg containing the resin becomes insufficient, which is preferable. Absent.

Specific examples of the bifunctional epoxy resin include:
Bisphenol such as bisphenol A type epoxy resin obtained from bisphenol A, bisphenol F type epoxy resin obtained from bisphenol F, bisphenol S type epoxy resin obtained from bisphenol S, and tetrabromobisphenol A type epoxy resin obtained from tetrabromobisphenol A Type epoxy resin, resorcin diglycidyl ether, hydroquinone diglycidyl ether, 4,4'-dihydroxy-3,3 ', 5,5'-tetramethylbiphenyl diglycidyl ether, diglycidyl ether of 1,6-dihydroxynaphthalene, 9 Diglycidyl ether of 9,9-bis (4-hydroxyphenyl) fluorene, isocyanate modified product of bisphenol A type epoxy resin, diglycidylaniline, diglycidyl phthalate, diterephthalate Glycidyl esters, dimer acid diglycidyl ester, polyepoxides, and obtained by oxidizing a compound having two double bonds in the molecule.

The difunctional epoxy resin in the present invention is
100% by weight of a bifunctional epoxy resin having an epoxy equivalent of 750 or more, more preferably 900 or more, and further preferably 1000 or more.
It is preferable to contain 10 to 50% by weight. More preferably, the epoxy equivalent is preferably 750 or more 2.
The functional epoxy resin is contained in the range of 10 to 40% by weight in 100% by weight of the bifunctional epoxy resin.
If the epoxy equivalent is less than 750, the cured resin product may not exhibit sufficient tensile elongation at break, toughness, and plastic deformability. By adding an appropriate amount of a bifunctional epoxy resin having an epoxy equivalent of 750 or more, it is possible to impart a higher degree of toughness and plastic deformability to the resin cured product and improve the strength of the fiber-reinforced composite material. If the compounding ratio is less than 10% 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, impregnating ability into reinforcing fibers and prepregs It may impair the handling properties such as the adhesiveness of the prepreg and the flexibility of the prepreg.

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 using 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.

Further, the bifunctional epoxy resin in the present invention preferably contains a bisphenol F type epoxy resin in an amount of 10 to 80% by weight, more preferably 20 to 70% 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. In particular, when a bifunctional epoxy resin having an epoxy equivalent of 750 or more, which tends to have a high viscosity, is contained, it is preferable to combine this with a bisphenol F type epoxy resin. 1
If it is less than 0% by weight, the effect of adjusting viscoelasticity and plastic deformation ability is often insufficient, and if it exceeds 80% by weight, heat resistance is often insufficient.

The epoxy resin composition used in the present invention includes
In order to improve the heat resistance of the obtained fiber-reinforced composite material tubular body, etc., it has more than two epoxy groups in the molecule to the extent that tensile rupture elongation, toughness and plastic deformation ability of the cured resin are not significantly impaired. It is preferable to include a polyfunctional epoxy resin.

As the polyfunctional epoxy resin, tris (p
-Hydroxyphenyl) methane triglycidyl ether, tetrakis (p-hydroxyphenyl) ethane tetraglycidyl ether, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether, phenols, alkylphenols, halogenated phenols and other phenol derivatives Examples thereof include glycidyl ester of novolac, tetraglycidyl diaminodiphenylmethane, tetraglycidyl-m-xylylenediamine, triglycidyl-m-aminophenol, triglycidyl-p-aminophenol, triglycidyl isocyanurate and the like.

As the curing agent for the constituent element (C) in the present invention, 4,4'-diaminodiphenylmethane, 4,
4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, m-phenylenediamine, m-
Active hydrogen such as aromatic amine having active hydrogen such as xylylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, bis (aminomethyl) norbornane, bis (4-aminocyclohexyl) methane, dimer acid ester of polyethyleneimine An aliphatic amine having a modified amine, a modified amine obtained by reacting an amine having these active hydrogen with a compound such as an epoxy compound, acrylonitrile, phenol and formaldehyde or thiourea, dimethylaniline, dimethylbenzylamine, 2,4,6- No active hydrogen-containing tertiary amines such as tris (dimethylaminomethyl) phenol and 1-substituted imidazole, dicyandiamide, tetramethylguanidine, hexahydrophthalic anhydride, tetrahydrophthalic acid Compounds, methylhexahydrophthalic anhydride, carboxylic acid anhydrides such as methyl nadic acid anhydride, polycarboxylic acid hydrazides such as adipic hydrazide and naphthalene dicarboxylic acid hydrazide, polyphenol compounds such as novolak resins, thioglycolic acid Polymercaptans, such as esters of polyols,
Examples thereof include Lewis acid complexes such as boron trifluoride ethylamine complex and aromatic sulfonium salts.

These curing agents may be combined with an appropriate curing auxiliary agent to enhance the curing 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 present invention, the above-mentioned component (A),
In addition to (B) and (C), other components such as polymer compounds and organic or inorganic particles can be included.

A thermoplastic resin is preferably used as the polymer compound. By blending the thermoplastic resin, the effects of controlling the viscosity of the resin, controlling the handleability of the prepreg, and improving the tackiness are enhanced, which is preferable.

Examples of thermoplastic resins that can be preferably 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 the thermoplastic resin in an amount of 1 to 20 parts by weight based on 100 parts by weight of the epoxy resin gives the epoxy resin composition an appropriate viscoelasticity and provides a good composite material. It is preferable in that physical properties can be obtained.

An uncured epoxy resin composition which comprises the constituents (B), (C) and, if necessary, other components and is present by being impregnated into the carbon fiber of the constituent (A) in the prepreg of the present invention. Regarding the viscoelasticity of the product, in order to obtain good handling of the prepreg, the measurement frequency is 0.5H.
z, storage modulus G ′ at 50 ° C. is 300 to 50000P
It is preferably a. 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 the prepregs are immediately peeled off in the prepreg laminating step, which hinders the laminating work. It may come. Also G'is 5000
If it exceeds 0 Pa, the flexibility of the prepreg may be deteriorated, the shapeability on the curved surface may not be sufficient, and the impregnation property into the reinforcing fiber may be deteriorated. Such viscoelasticity is achieved by optimizing the type and mixing ratio of the epoxy resin component contained in the constituent element (B), or by including an appropriate amount of the thermoplastic resin.

The prepreg of the present invention has an adhesive strength of 0.050 to 0.150 N, which is measured under the conditions described below, in order to produce a tubular body made of a fiber-reinforced composite material.
/ Mm ² is preferable. If the adhesive strength of the prepreg is less than 0.050 N / mm ² , the prepregs stacked in the prepreg laminating step may be immediately peeled off, which may hinder the laminating operation. Also, 0.150
If it exceeds N / mm 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 preferable adhesive strength, defects such as disorder of fiber orientation are likely to occur inside the tubular body, but in particular, a fiber composite material tubular tube to which reinforcing fibers having a high elastic modulus are applied. In the case of the body, it is susceptible to strength reduction due to such defects. Therefore, the tensile modulus is 320 GPa
In the case of the prepreg of the present invention to which carbon fiber of 600 GPa is applied, the adhesive strength is 0.050 to 0.150 N / m.
It is preferably m ² .

If a cover film or the like is not attached to the prepreg surface and the prepreg surface is left exposed to the atmosphere, the adhesive strength of the prepreg may decrease with time. However, in the present invention, Not only immediately after peeling off the cover film or release paper attached to the prepreg surface, but also after leaving the prepreg surface exposed to the air for 24 hours at 24 ° C. and 50% RH. Prepreg adhesive strength 0.050
From the standpoint of work efficiency, it is preferably 0.150 N / mm ² .

In order to develop such prepreg adhesive strength and, in turn, to sufficiently develop the torsional strength of the tubular body, it is preferable that the hook drop value of the carbon fiber is in the range of 100 to 1000 mm. The hook drop value is an index of fiber sizing property as described below. In general, carbon fibers are used to prevent process troubles such as winding of broken filaments around rollers during the manufacturing process, and to prevent the spread of carbon fibers with a carbon fiber supply creel, guides, and combs during prepreg manufacturing. In order to improve the process passability, the focusing property is imparted.
As a method of bundling the carbon fibers, there are a method of giving entanglement, a method of giving twist, and a method of giving a sizing agent to the filaments of the fiber bundle. When twist is applied, the twist may be released after passing through the process. However, when the carbon fibers are bundled, the process passability is improved, but in the production of the prepreg, the impregnating property of the matrix resin is lowered due to the bundling property. Further, in the method of releasing after twisting, since twisting and twisting remain in the carbon fiber, the manufactured prepreg is not smooth and has unevenness on the surface, which adversely affects the physical properties of the composite material. Increasing the hook drop value improves resin impregnation and surface smoothness in the production of prepregs, but carbon fiber bundles spread too much in the carbon fiber supply creel, guides, and combs, causing fluff and poor processability. Such,
It is easy to cause trouble.

From this point, the more preferable hook drop value of the carbon fiber bundle is 120 mm or more and 700 mm or less. By having the hook drop value in this range,
When the prepreg is processed, the single yarns in the carbon fiber bundle are easily diffused by the resin, and stress is less likely to accumulate inside the prepreg.Therefore, even if the prepreg surface after processing is left at room temperature for a long time, the carbon fiber It rarely moves and floats on the surface, and as a result, it is easy to obtain a prepreg with excellent surface smoothness, excellent tackiness, and little change over time.

Here, the hook drop value measurement is performed in the following procedure. That is, temperature 23 ± 2 ° C, humidity 50 ± 5%
The carbon fiber bundle is left for 2 hours in the atmosphere. A carbon fiber bundle is cut into a length of 1.5 m, and a load of 100 g is applied to the lower portion of the carbon fiber bundle to suspend the fiber bundle vertically. 1mmφ and 100m in length
Bending the lower part of stainless steel wire of about 20 m to 30 mm and applying a load so that the total weight is 12 g,
The upper part of 20 to 30 mm is bent in a U shape and hooked at the center in the width direction of the fiber bundle. The drop distance (unit: cm) of the load after 30 minutes has passed is the hook drop value. Twist,
This value becomes small if there is a twist. Measure at least 5 times and take the average value.

Further, in order to obtain an appropriate adhesive strength of the 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 present on the surface (hereinafter referred to as the amount of the surface resin), and the larger the amount of the 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.

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 320 GPa to 600 GPa such as the constituent element (A) at such an angle, 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 component (A) is arranged at such an angle that the weight can be reduced while keeping the torsional rigidity and the torsional strength within appropriate ranges. Is particularly preferred.

In the tubular body made of the fiber reinforced composite material of the present invention, the glass transition temperature of the cured product of the epoxy resin (hereinafter, simply referred to as a cured resin product) is preferably 80 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 increases and the strength characteristics thereof may deteriorate, which is not preferable. When 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, which is not preferable. The glass transition temperature of the resin cured product is a value measured by a differential scanning calorimetry (DSC), but by measuring a sample cut out from the tubular body, the resin cured product contained in the tubular body can be measured. The glass transition temperature can be measured.

In order to impart high strength characteristics, impact resistance, etc. to the tubular body made of the fiber-reinforced composite material of the present invention, the cured resin is subjected to the compact tension method according to ASTM-E399 or ASTM E5045-91. The mode I fracture toughness value G _{IC at the} early stage of crack growth of the resin cured product measured by the compliant SENB method is preferably 200 J / m ² or more, and more preferably 400 J / m ² or more.

In order to impart high strength characteristics and impact resistance to the tubular body made of the fiber-reinforced composite material of the present invention, the cured resin product has a tensile elongation at break of 8% measured according to JIS K7113. The above is preferable. Here, the G _IC and the tensile elongation at break of the resin cured product are measured for a cured product obtained by subjecting the epoxy resin composition of the present invention to a heat treatment at 130 ° C. for 90 minutes.

Hereinafter, a method for producing a prepreg which can be suitably applied in the present invention, and a method for laminating the prepregs and curing them by heating to obtain a tubular body 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 reduce its viscosity and impregnated, or a hot melt method in which the 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 fiber 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 fiber 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 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.

Methods for applying heat and pressure include 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 cored bar such as a mandrel, and is suitable for producing rod-shaped bodies such as golf club shafts and fishing rods. 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.

[0064]

EXAMPLES The present invention will be described in detail below with reference to examples. Measurement of carbon fiber bundle strength, measurement of carbon fiber strand tensile modulus / strength, preparation of prepreg, adhesion of prepreg, preparation of tubular body, measurement of glass transition temperature (Tg) of cured epoxy resin, tubular body The torsional strength of was measured by the following method. Since the feel when swinging a golf shaft greatly depends on the elastic modulus of the carbon fibers used, the torsional strength of the tubular body should be compared between those using carbon fibers having the same strand tensile elastic modulus. Is. However, in general, when high elastic modulus carbon fiber is used, it is easy to realize high performance such as high rigidity and light weight.Therefore, the value obtained by multiplying the torsional strength and the strand elastic modulus is used as a convenient high performance index. Shown in 1. (1) Measurement of bundle strength of carbon fiber Carbon fiber was not impregnated with resin but was held by an air chuck as it was, pulled at a test length of 50 mm and a pulling speed of 5 to 100 mm / min to obtain breaking strength, and an average of n = 5 was obtained. It was When the bundle strength is poor at the time of measuring the bundle strength and it cannot be gripped by the chuck with good alignment, the yarn bundle may be focused through a water bath and measured in a wet state. (2) 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 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) (3) Preparation of prepreg Resin composition was prepared using a reverse roll coater. It was applied onto release paper to prepare a resin film having a resin areal weight of 20 g / m ² . Next, two resin films are superposed on both sides of the carbon fibers on the carbon fibers arranged in a sheet shape in one direction, and the temperature is 100 ° C.
The resin composition is impregnated by sandwiching it with a heated metal roll and applying heat and pressure.

After impregnation, the release paper on one side is peeled off from the prepreg, a polyethylene film is attached to the surface on 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 , the carbon fiber content is 76% by weight.
I got a prepreg. (4) Adhesive strength measurement of prepreg By the following operations (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
4.5 so that it becomes mm × 10 mm (= 100 mm ² ).
After pressing for 1 second with a load of kgf, set prepreg B to 3
The peeling force when peeling in the direction perpendicular to the surface of the prepreg A at a speed of 0 mm / min was measured, and the value obtained by dividing this by the contact area (100 mm ² ) was taken as the adhesive strength of the prepreg. (5) Fabrication of tubular body made of fiber composite material By the following operations (a) to (e), a fiber composite having a laminated constitution of [0 ₃ / ± 45 ₃ ] in the cylindrical axis direction and an inner diameter of 10 mm A tubular body made of 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) 800 mm length x 1 width so that the fiber direction is 45 degrees with respect to the axial direction of the mandrel.
Two pieces were cut into a rectangle of 06 mm. The two sheets were attached with a shift of 16 mm (corresponding to half the mandrel circumference) so that the fiber directions intersect each other. (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. (Biasing material) (c) On top of that, a prepreg is cut into a rectangle of 800 mm length × 118 mm width so that the fiber direction is in the longitudinal direction so that the longitudinal direction of the prepreg and the axial direction of the mandrel are aligned. Wrapped around. (Straight material) (d) A wrapping tape (heat-resistant film tape) was wrapped around, and heat-molded in a curing oven at 130 ° C. for 90 minutes. (E) After molding, the mandrel was pulled out and the wrapping tape was removed to obtain a tubular body. (6) 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. (7) Measurement of torsional strength of tubular body A test piece with a length of 400 mm was cut out from a tubular body having an inner diameter of 10 mm, and "golf club shaft certification standard and standard confirmation method" (Product Safety Association, commonly known as the 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
m) × twist angle at break (deg) (Example 1) The following raw materials were mixed with a kneader to obtain a resin composition in which polyvinyl formal was uniformly dissolved.

Bisphenol A type bifunctional epoxy resin ("Epicoat" 828, registered trademark, manufactured by Japan Epoxy Resins Co., average epoxy equivalent 184-194) 5
0 parts by weight bisphenol A type bifunctional epoxy resin ("Epicoat" 1001, registered trademark, manufactured by Japan Epoxy Resins Co., average epoxy equivalent 450-500) 30 parts by weight bisphenol A type bifunctional epoxy resin ("Epicoat" 1004, Registered trademark, manufactured by Japan Epoxy Resin Co., Ltd., average epoxy equivalent 875-975) 20 parts by weight Dicyandiamide ("Epicure" DICY-7, registered trademark, manufactured by Japan Epoxy Resin Co., Ltd.) 5 parts by weight 3- (3,4) -Dichlorophenyl) -1,1-dimethylurea (DCMU99, model number, Hodogaya Chemical Co., Ltd.
4 parts by weight of polyvinyl formal (“Vinylec” K, registered trademark,
Chisso Co., Ltd.) 4 parts by weight This resin composition and a tensile modulus of elasticity aligned in one direction 38
A sheet-shaped prepreg (A-1) was produced according to the above-mentioned operation using 1 GPa and a bundle strength of 726 N / bundle of carbon fibers.

The adhesive strength of the obtained prepreg (A-1) was measured by the above-mentioned operation on the surface on the side where the polyethylene film was attached. The measurement is within 10 minutes after peeling off the polyethylene film, and at 23 ° C. and 50% RH with the surface exposed by peeling off the polyethylene film.
After being left for 24 hours in the above environment, the test was carried out twice, and as shown in Table 1, all showed good adhesive strength.

Prepreg P225 manufactured by Toray Industries, Inc. having a carbon fiber content having a tensile elastic modulus of 295 GPa of 76% by weight.
5F-12 (model number) is straight material, prepreg (A-
Using 1) as a bias material, a tubular body was produced by the method described above, and its twist strength and Tg of the resin cured product of the bias material were measured. The results are summarized in Table 1. (Example 2) The same resin composition as in Example 1, a tensile elastic modulus of 393 GPa aligned in one direction, and a bundle strength of 745 N /
Using a bundle of carbon fibers, a sheet-like prepreg (A-2) was produced according to the above-mentioned operation.

The adhesive strength of the obtained prepreg (A-2) was measured on the surface to which the polyethylene film was attached by the above-mentioned operation. The measurement was performed within 3 minutes after the polyethylene film was peeled off, and twice after the polyethylene film was peeled off and the surface was exposed in the environment of 23 ° C. and 50% RH for 24 hours. As shown, all of them showed good adhesive strength.

Prepreg P manufactured by Toray Industries, Inc. as in Example 1
2255F-12 (model number) was used as a straight material and prepreg (A-2) was used as a bias material to prepare a tubular body by the method described above, and its torsional strength and Tg of a resin cured product of the bias material were measured. . The results are summarized in Table 1. (Example 3) The following raw materials were mixed with a kneader to obtain a resin composition in which polyvinyl formal was uniformly dissolved.

Bisphenol A type bifunctional epoxy resin ("Epicoat" 828, registered trademark, manufactured by Japan Epoxy Resins Co., average epoxy equivalent 184-194) 4
0 parts by weight bisphenol F-type bifunctional epoxy resin ("Epicoat" 807, registered trademark, Japan Epoxy Resin Co., Ltd.)
Made, average epoxy equivalent 160-175) 20 parts by weight bisphenol F-type bifunctional epoxy resin ("Epicoat" 4010P, registered trademark, Japan Epoxy Resin Co., Ltd., average epoxy equivalent 4400) 30 parts by weight phenol novolac type polyfunctional Epoxy resin ("Epicote" 154, registered trademark, manufactured by Japan Epoxy Resins Co., Ltd., average epoxy equivalent 176-180) 10 parts by weight dicyandiamide ("Epicure" DICY-7, registered trademark, manufactured by Japan Epoxy Resins Co., Ltd.) 5 Parts by weight 3- (3,4-dichlorophenyl) -1,1-dimethylurea (DCMU99, model number, Hodogaya Chemical Co., Ltd.)
4 parts by weight of polyvinyl formal (“Vinylec” K, registered trademark,
Chisso Co., Ltd.) 4 parts by weight Using this resin composition and the same unidirectional tensile elastic modulus of 381 GPa and bundle strength of 726 N / bundle of carbon fibers, a sheet-like prepreg is prepared according to the above-mentioned operation. (A-3) was produced.

The adhesive strength of the obtained prepreg (A-3) was measured on the surface on the side where the polyethylene film was attached by the above-mentioned operation. The measurement is within 10 minutes after peeling off the polyethylene film, and at 23 ° C. and 50% RH with the surface exposed by peeling off the polyethylene film.
After being left for 24 hours in the above environment, the test was carried out twice, and as shown in Table 1, all showed good adhesive strength.

Prepreg P manufactured by Toray Industries, Inc. as in Example 1
2255F-12 (model number) was used as a straight material and prepreg (A-3) was used as a bias material to prepare a tubular body by the method described above, and its torsional strength and Tg of a resin cured product of the bias material were measured. . The results are summarized in Table 1. (Comparative Example 1) The same resin composition as in Example 1, a tensile elastic modulus of 375 GPa aligned in one direction, and a bundle strength of 510 N /
Using a bundle of carbon fibers, a sheet-like prepreg (B-1) was produced according to the above-mentioned operation.

The adhesive strength of the obtained prepreg (B-1) was measured on the surface to which the polyethylene film was attached by the above-mentioned operation. The measurement was performed within 3 minutes after the polyethylene film was peeled off, and a total of 2 times after the polyethylene film was peeled off and the surface was exposed in an environment of 23 ° C and 50% RH for 24 hours.

Prepreg P manufactured by Toray Industries, Inc. as in Example 1
2255F-12 (model number) was used as a straight material and prepreg (B-1) was used as a bias material to prepare a tubular body by the method described above, and its torsional strength and Tg of a cured resin material of the bias material were measured. . The results are collectively shown in Table 1. Since the bundle strength of the carbon fibers in the constituent element (A) is as low as 510 N / bundle, the torsional strength of the tubular body is low as compared with Examples 1 and 2. Became. (Comparative Example 2) The following raw materials were mixed with a kneader to obtain a resin composition in which polyvinyl formal was uniformly dissolved.

Bisphenol A type bifunctional epoxy resin ("Epicoat" 828, registered trademark, manufactured by Japan Epoxy Resins Co., Ltd., average epoxy equivalent 184-194) 4
0 parts by weight bisphenol F-type bifunctional epoxy resin ("Epicoat" 807, registered trademark, Japan Epoxy Resin Co., Ltd.)
Made, average epoxy equivalent 160-175) 20 parts by weight bisphenol F type bifunctional epoxy resin ("Epicoat" 4010P, registered trademark, Japan Epoxy Resin Co., Ltd., average epoxy equivalent 4400) 10 parts by weight phenol novolac type epoxy resin ("Epicote"
154, registered trademark, manufactured by Japan Epoxy Resins Co., Ltd.,
Average epoxy equivalent 176 to 180) 30 parts by weight Dicyandiamide ("Epicure" DICY-7, registered trademark, manufactured by Japan Epoxy Resins Co., Ltd.) 5 parts 3- (3,4-dichlorophenyl) -1,1-dimethylurea (DCMU99 , Model number, Hodogaya Chemical Co., Ltd.
4 parts by weight of polyvinyl formal (“Vinylec” K, registered trademark,
Chisso Co., Ltd.) 5 parts by weight Using this resin composition and the same unidirectional tensile elastic modulus of 381 GPa and bundle strength of 726 N / bundle of carbon fibers, a sheet-like prepreg is prepared according to the above-mentioned operation. (B-2) was produced.

The adhesive strength of the obtained prepreg (B-2) was measured on the surface on the side where the polyethylene film was attached by the above-mentioned operation. The measurement is within 10 minutes after peeling off the polyethylene film, and at 23 ° C. and 50% RH with the surface exposed by peeling off the polyethylene film.
After being left for 24 hours in the above environment, the test was performed twice.

Next, prepreg P2255 manufactured by Toray Industries, Inc.
Using F-12 (model number) as a straight material and prepreg (B-2) as a bias material, a tubular body was prepared by the method described above, and its twist strength and Tg of a cured resin material of the bias material were measured. . The results are collectively shown in Table 1. Since the content of the bifunctional epoxy resin in the constituent element (B) is as low as 70% by weight, the torsional strength of the tubular body is low as compared with Examples 1 and 3. It became a value. Example 4 The following raw materials were mixed with a kneader to obtain a resin composition in which polyvinyl formal was uniformly dissolved.

Bisphenol F type bifunctional epoxy resin ("Epicoat" 828, registered trademark, manufactured by Japan Epoxy Resins Co., Ltd., average epoxy equivalent 184-194) 5
0 parts by weight bisphenol A type bifunctional epoxy resin ("Epicoat" 1001, registered trademark, manufactured by Japan Epoxy Resins Co., average epoxy equivalent 450-500) 30 parts by weight bisphenol A type bifunctional epoxy resin ("Epicoat") 1004, registered trademark, Japan Epoxy Resin Co., Ltd., average epoxy equivalent 875-975) 20 parts by weight Dicyandiamide ("Epicure" DICY-7, registered trademark, Japan Epoxy Resin Co., Ltd.) 5 parts by weight 3- (3 , 4-Dichlorophenyl) -1,1-dimethylurea (DCMU99, model number, Hodogaya Chemical Co., Ltd.)
4 parts by weight of polyvinyl formal (“Vinylec” K, registered trademark,
Chisso Co., Ltd.) 4 parts by weight This resin composition and a tensile elastic modulus 43 aligned in one direction
A sheet-like prepreg (A-4) was produced according to the above-described operation using 9 GPa and a bundle strength of 695 N / bundle of carbon fibers.

The adhesive strength of the obtained prepreg (A-4) was measured by the above-mentioned operation for the surface on the side where the polyethylene film was attached. The measurement is within 10 minutes after peeling off the polyethylene film, and at 23 ° C. and 50% RH with the surface exposed by peeling off the polyethylene film.
After being left for 24 hours in the above environment, the test was carried out twice, and as shown in Table 1, all showed good adhesive strength.

Next, prepreg P2255 manufactured by Toray Industries, Inc.
Using F-12 (model number) as a straight material and prepreg (A-4) as a bias material, a tubular body was produced by the method described above, and its twist strength and Tg of a cured resin material of the bias material were measured. . The results are summarized in Table 1. (Example 5) The same resin composition as in Example 4, a tensile elastic modulus of 438 GPa aligned in one direction, and a bundle strength of 620 N /
Using a bundle of carbon fibers, a sheet-like prepreg (A-5) was produced according to the above-mentioned operation.

The adhesive strength of the obtained prepreg (A-5) was measured on the surface on the side where the polyethylene film was attached by the above-mentioned operation. The measurement was performed within 3 minutes after the polyethylene film was peeled off, and twice after the polyethylene film was peeled off and the surface was exposed in the environment of 23 ° C. and 50% RH for 24 hours. As shown, all of them showed good adhesive strength.

Prepreg P manufactured by Toray Industries, Inc. as in Example 1
2255F-12 (model number) was used as a straight material and prepreg (A-5) was used as a bias material to prepare a tubular body by the method described above, and its torsional strength and Tg of a cured resin material of the bias material were measured. . The results are summarized in Table 1. (Example 6) The same resin composition as in Example 4, a tensile elastic modulus of 435 GPa aligned in one direction, and a bundle strength of 520 N /
Using a bundle of carbon fibers, a sheet-like prepreg (A-6) was produced according to the above-mentioned operation.

The adhesive strength of the obtained prepreg (A-6) was measured on the surface on the side where the polyethylene film was attached by the above-mentioned operation. The measurement was performed within 3 minutes after the polyethylene film was peeled off, and twice after the polyethylene film was peeled off and the surface was exposed in the environment of 23 ° C. and 50% RH for 24 hours. As shown, all of them showed good adhesive strength.

Prepreg P manufactured by Toray Industries, Inc. as in Example 1
Using 2255F-12 (model number) as a straight material and prepreg (A-6) as a bias material, a tubular body was prepared by the method described above, and its twist strength and Tg of a resin cured product of the bias material were measured. . The results are summarized in Table 1. (Comparative Example 3) The same resin composition as in Example 4, a tensile elastic modulus of 431 GPa aligned in one direction, and a bundle strength of 480 N /
A sheet-shaped prepreg (B-3) was produced using the bundle of carbon fibers according to the above-described operation.

The adhesive strength of the obtained prepreg (B-3) was measured on the surface on the side where the polyethylene film was attached by the above-mentioned operation. The measurement was performed within 3 minutes after the polyethylene film was peeled off, and a total of 2 times after the polyethylene film was peeled off and the surface was exposed in an environment of 23 ° C and 50% RH for 24 hours.

Prepreg P manufactured by Toray Industries, Inc. as in Example 1
2255F-12 (model number) was used as a straight material and prepreg (B-3) was used as a bias material to prepare a tubular body by the method described above, and its torsional strength and Tg of a cured resin material of the bias material were measured. . The results are collectively shown in Table 1. Since the bundle strength of the carbon fibers in the constituent element (A) is as low as 480 N / bundle, the torsional strength of the tubular body is higher than those of Examples 4, 5 and 6. It became a low value. (Comparative Example 4) The following raw materials were mixed with a kneader to obtain a resin composition in which polyvinyl formal was uniformly dissolved.

Bisphenol F-type bifunctional epoxy resin ("Epicoat" 807, registered trademark Japan Epoxy Resins Co., Ltd., average epoxy equivalent 160-175) 50
Parts by weight Bisphenol A type bifunctional epoxy resin (“Epicoat” 1009, registered trademark, manufactured by Japan Epoxy Resins Co., Ltd., average epoxy equivalent 2400-3300) 20
Phenolic novolac type epoxy resin (“Epicoat”)
154, registered trademark, manufactured by Japan Epoxy Resins Co., Ltd.,
Average epoxy equivalent 176 to 180) 30 parts by weight Dicyandiamide ("Epicure" DICY-7, registered trademark, manufactured by Japan Epoxy Resins Co., Ltd.) 5 parts by weight 3- (3,4-dichlorophenyl) -1,1-dimethylurea ( DCMU99, model number, Hodogaya Chemical Co., Ltd.
4 parts by weight of polyvinyl formal (“Vinylec” K, registered trademark,
Chisso Co., Ltd.) 3 parts by weight Using this resin composition and the same unidirectional tensile elastic modulus of 439 GPa and bundle strength of 695 N / bundle of carbon fibers, a sheet-like prepreg is prepared according to the above-mentioned operation. (B-4) was produced.

The adhesive strength of the obtained prepreg (B-4) was measured on the surface on the side where the polyethylene film was attached by the above-mentioned operation. The measurement is within 10 minutes after peeling off the polyethylene film, and at 23 ° C. and 50% RH with the surface exposed by peeling off the polyethylene film.
After being left for 24 hours in the above environment, the test was performed twice.

Next, prepreg P2255 manufactured by Toray Industries, Inc.
Using F-12 (model number) as a straight material and prepreg (B-4) as a bias material, a tubular body was prepared by the above-described method, and its torsional strength and Tg of a resin cured product of the bias material were measured. . The results are collectively shown in Table 1. Since the proportion of the component (B) containing the bifunctional epoxy resin was as low as 70% by weight, the twisting strength of the tubular body was lower than that of Example 4. became.

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[Table 1]

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INDUSTRIAL APPLICABILITY The tubular body made of the fiber-reinforced composite material using the prepreg of the present invention has excellent torsional strength.
This makes it possible to obtain a tubular body made of a fiber-reinforced composite material, which has excellent impact strength and is also lightweight.

The fiber-reinforced composite material tubular body of the present invention is suitably 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 (8)

[Claims] 1. A tensile strength Y (N / bundle) of a fiber bundle comprising the following constituents (A), (B) and (C) and having a number of single yarns of 12,000 as the constituent (A). A prepreg characterized in that the strand tensile elastic modulus X (GPa) satisfies the following relationship. Y ≧ -4X / 3 + 1070 (A) 100% by weight of carbon fiber (B), 75 to 1 of bifunctional epoxy resin
Epoxy resin (C) curing agent containing 100% by weight 2. The tensile strength Y (N / bundle) of a fiber bundle comprising the following constituent elements (A), (B) and (C), and having a number of single yarns of the constituent element (A) of 12000. 550 N / bundle or more, and the strand tensile elastic modulus X is 320 GPa or more
Prepreg characterized by being in the range of 600 GPa. In (A) 100% by weight of carbon fiber (B), 75 to 1 of bifunctional epoxy resin
Epoxy resin (C) curing agent containing 100% by weight 3. In 100% by weight of a bifunctional epoxy resin,
Epoxy resin having an epoxy equivalent of 750 or more is 10
The prepreg according to claim 1 or 2, which comprises 50% by weight. 4. In 100% by weight of a bifunctional epoxy resin,
The prepreg according to any one of claims 1 to 3, which comprises 10 to 80% by weight of a bisphenol F type epoxy resin. 5. The adhesive strength between the prepreg surfaces is 0.05.
0 to 0.150 N / mm ²It is any one of Claims 1-4 which is
The prepreg described in the crab. 6. A fiber-reinforced composite material tubular body comprising a layer formed by heat-curing the prepreg according to any one of claims 1 to 5. 7. The component (A) is aligned in one direction and the fiber orientation of the component (A) is arranged at an angle of 20 ° to 90 # with respect to the longitudinal direction of the tubular body. The tubular body made of the fiber-reinforced composite material according to claim 6. 8. The fiber-reinforced composite material tubular body according to claim 6, wherein the glass transition temperature of the cured product of the epoxy resin is 80 ° C. to 120 ° C.