JP2003277471A - Epoxy resin composition, prepreg and carbon fiber- reinforced composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight tubular body made of a fiber-reinforced composite material, having excellent strength characteristics to a compression stress in the direction different from the fiber direction, and to provide a prepreg and an epoxy resin composition for providing the tubular body. <P>SOLUTION: The epoxy resin composition for the carbon fiber-reinforced composite material comprises constituent elements of (A) an epoxy resin and (B) a curing agent. The cured product of the resin after heat curing has 110-140 MPa compression yield stress and 6-10% nominal strain at compression yield. The prepreg is obtained by impregnating carbon fibers with the epoxy resin composition. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a carbon fiber reinforced composite material suitable for sports applications, aerospace applications, and general industrial applications, an epoxy resin composition as a matrix resin for obtaining the same, and a prepreg.

[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.

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

In a carbon fiber 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 # compression strength) is high. Strength) is low compared to 0 # tensile strength, and several approaches have been disclosed to improve this.

For example, Japanese Patent Laid-Open No. 2001-131833 discloses a method of improving the compressive strength of carbon fibers themselves 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 where 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.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to reinforce the carbon fiber reinforced by solving the problems of the prior art and imparting excellent material strength to various structural materials and weight reduction of sports equipment. A composite material, an epoxy resin composition for obtaining the same, and a prepreg are provided.

[0009]

In order to achieve the above object, the present invention has the following constitution. That is, the following components (A) and (B) are included, and the compression yield stress of the resin cured product after heat curing is 110 to 140 MPa, and the nominal strain at compression yield is 6 to 10%. An epoxy resin composition for a carbon fiber reinforced composite material, comprising: (A) Epoxy resin (B) Hardener Further, the prepreg of the present invention is characterized in that carbon fiber is impregnated with the epoxy resin composition.

Further, the carbon fiber reinforced composite material of the present invention is characterized by comprising a resin cured product obtained by heating and curing such an epoxy resin composition and carbon fiber.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies conducted by the present inventors in order to solve the above-mentioned problems, as to the cured resin for carbon fiber reinforced composite material, the yield stress is controlled within a specific range and at the same time, the nominal strain at the time of compressive yield is set. By setting the value to a specific range, the strength under compressive stress in the direction that forms a constant angle of more than 0 # and less than 90 # with the fiber direction (hereinafter referred to as non-fiber direction compressive strength) is improved. I found that it is possible. Further, they have found that the torsional strength of a tubular body molded from a prepreg obtained by impregnating carbon fiber with such a resin is remarkably improved, which has led to the present invention.

The present invention will be described in detail below.

The epoxy resin composition of the present invention is characterized in that the cured product of the resin obtained by heating and curing is controlled in the compressive yield stress and the nominal strain at the compressive yield within a specific range. Has a side length of 6 mm ± 0.
A test piece cut out from a resin cured product so as to have a cube of 2 mm is measured at a test speed of 1 ± 0.2 mm / min and other conditions according to JIS K7181. The resin cured product to be subjected to such a compression test is obtained by heating the uncured resin composition at a constant temperature selected from the range of 100 ° C to 200 ° C for 90 minutes.

The compressive yield stress of the resin cured product obtained by heat curing the epoxy resin composition of the present invention is 110-14.
Need to be 0 MPa, 115-140MP
It is preferably a, and more preferably 120 to 140 MPa. Such compressive yield stress is 110MP
If it is less than a, the compressive strength of the fiber-reinforced composite material will be insufficient due to insufficient proof stress against compressive stress, and if it exceeds 140 MPa, the residual thermal stress in the material will be large. It is not preferable because it may cause a decrease in

At the same time that the compressive yield stress is within the above specified range, it is necessary that the resin cured product obtained from the epoxy resin composition of the present invention has a nominal strain at the time of compressive yield of 6 to 10%. It is more preferably 9.5%.
If the nominal strain during compression yielding is less than 6%, sufficient yield strength cannot be exhibited when a compressive stress is applied, and the compressive strength of the fiber-reinforced composite material cannot be sufficiently exhibited. Further, if the nominal strain during compressive yield exceeds 10%, when stress is applied to the fiber-reinforced composite material tubular body in the torsional direction, the tubular body is easily broken by the multiaxial composite stress.

The compression modulus of the resin cured product obtained by heating and curing the epoxy resin composition of the present invention is preferably 2.3 to 3.5 GPa in order to exhibit excellent material strength. More preferably, it is 0.3 to 3.4 GPa. More preferably, it is 2.6 to 3.3 GPa.
If the compressive elastic modulus is less than 2.3 GPa, the compressive strength of the fiber-reinforced composite material may be insufficient, and 3.5
If it exceeds GPa, the cured resin may become brittle, or the residual thermal stress in the fiber-reinforced composite material may become large, so that the tensile strength of the fiber-reinforced composite material may be deteriorated.

Further, in addition to such compression elastic modulus, it is preferable that the cured resin obtained from the epoxy resin composition of the present invention has a nominal strain of 50% or more at the time of compression failure. It is more preferably 55% or more, further preferably 60% or more. By setting the compressive elastic modulus to the above range and at the same time to set the nominal strain at the time of compressive failure to a high level range, the direction of the fiber and 0 #
The strength under the compressive stress in the direction at a constant angle of less than 0 # (hereinafter, referred to as the compressive strength in the non-fiber direction) is easily expressed. If the nominal strain at the time of compressive failure is less than 50%, the resin becomes brittle and is easily broken by the multiaxial compound stress applied when the tubular body made of the fiber-reinforced composite material is twisted.

The higher the nominal strain at the time of compression failure, the more preferable, but 90% is sufficient in view of the balance with the strain of the carbon fiber.

In the present invention, the constituent element (A) is an epoxy resin. In order to develop the resin compression characteristics described above, it is preferable to include 75 to 100% by weight of a bifunctional epoxy resin in 100% by weight of the constituent element (A) in the present invention.

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 give a high yield stress without significantly reducing the nominal strain at the time of compression failure of the cured resin product, a bisphenol F type epoxy resin, a diglycidyl ether of 1,6-dihydroxynaphthalene, a diglycidyl of aniline. 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 10 to 10 of at least one epoxy resin in 100% by weight of 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 compression yield stress of the cured resin product may not be controlled within a preferable range.

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 5 to 50% by weight. If the epoxy equivalent is less than 750, the cured product may have too high a compressive yield stress or the resin may become brittle. By including an appropriate amount of a bifunctional epoxy resin having an epoxy equivalent of 750 or more, it is possible to impart a proper range of compressive yield stress and nominal strain at the time of compressive yield to a resin cured product, and improve the compressive strength in the non-fiber direction. Possible, but the compounding ratio is 5% by weight
If it is less than that, the effect may not be sufficient. Again 5
If it exceeds 0% by weight, the viscosity of the uncured resin composition becomes too high, which may impair the impregnation property into the reinforcing fiber, the adhesiveness between the prepregs, the handling property such as the flexibility of the prepreg, and the like.

In the epoxy resin composition of the present invention, in order to improve the heat resistance and the compressive yield stress of the resulting carbon fiber reinforced composite material, the nominal strain at the time of compressive failure of the cured resin product is not significantly impaired. It is preferable to include a polyfunctional epoxy resin having more than two epoxy groups in the molecule.

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.

In addition, in order to improve the compressive yield stress and the compressive elastic modulus without lowering the nominal strain at the time of compressive failure of the resin cured product, the constituent element (A) contains an imide skeleton such as N-glycidyl phthalimide. It is also preferable to include a monofunctional epoxy resin.

As the curing agent of the constituent element (B) in the present invention, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 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, an epoxy compound, an acrylonitrile, a phenol and formaldehyde, a modified amine obtained by reacting a compound such as thiourea with an amine having these active hydrogens, 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 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.

When it is necessary to perform heat curing at a lower curing temperature, an amine adduct type curing agent "Amicure" (registered trademark) PN-23, M manufactured by Ajinomoto Co., Inc.
Y-24, "Fujicure" (registered trademark) FXE-1000, FXR-1030, ACR manufactured by Fuji Kasei Kogyo Co., Ltd. as having an active hydrogen part and a catalyst part in the molecule.
H3615, H4070, H3293, H3 manufactured by
366, H3849, H3670, Shikoku Chemicals Co., Ltd.
"Cureduct" (registered trademark) P-0505, "Curesol" (registered trademark) 2E4MZ-CMS, CZ- manufactured by
CNS, C11Z-A, microcapsule type hardener "Novacure" (registered trademark) HX3 manufactured by Asahi Kasei Corporation
721, HX3722, etc., and these can be used alone or in combination.

The constituent element (C) in the present invention is rubber fine particles having an average primary particle diameter of 2 μm or less. It is generally known that the addition of rubber particles improves the fracture toughness of the resin, but it has been found that the fracture toughness can be remarkably improved by adding a small amount by adding the rubber particles to the resin cured product having the compression property. It was

The average primary particle diameter of the rubber fine particles is 2 μm.
The thickness is preferably the following, and more preferably 0.01 μm to 2 μm. The average primary particle size refers to the size of the basic unit before the rubber particles are aggregated. If the average primary particle size of the rubber fine particles exceeds 2 μm, the fracture toughness improving effect may not be obtained. The average primary particle diameter of the rubber fine particles in the present invention means a volume average. The average primary particle diameter can be obtained by using, for example, a laser diffraction type particle size distribution measuring device.

As the rubber fine particles, crosslinked rubber particles and core-shell rubber particles obtained by graft-polymerizing a different polymer on the surface of the crosslinked rubber particles are preferably used for improving the resin toughness and the impact resistance of the resulting composite material.

Commercially available products of crosslinked rubber particles include, for example,
XER-91 (average primary particle size 0.07 μm; manufactured by JSR Corp.), XER-91P (average primary particle size 0.07 μm; JSR (shares), which consists of a crosslinked product of a carboxyl-modified butadiene-acrylonitrile copolymer )), XER
-71 (average primary particle diameter 0.07 μm; JSR Corporation)
Manufactured), XER-71P (average primary particle diameter 0.07 μm;
JSR Corporation), XER-81 consisting of a cross-linked product of a glycidyl-modified butadiene-acrylonitrile copolymer.
(Average primary particle diameter 0.3 μm; manufactured by JSR Corporation), XE
R-81P (average primary particle diameter 0.3 μm; JSR Corporation)
Manufactured by JSR Co., Ltd.), DHS-2 consisting of acrylic rubber fine particles (average primary particle diameter 0.07 μm; manufactured by JSR Corporation), BPA3.
28 (average primary particle diameter 0.3 μm; manufactured by Nippon Shokubai Co., Ltd.), BPF307 (average primary particle diameter 0.3 μm;
Nippon Shokubai Co., Ltd., YR-528 (average primary particle diameter 0.3 μm; Nihon Shokubai Co., Ltd., Toto Kasei Co., Ltd.), Y
R-570 (average primary particle diameter 0.3 μm; manufactured by Nippon Shokubai Co., Ltd., Toto Kasei Co., Ltd.) can be used.

Examples of commercially available core-shell rubber particles include, for example, "Paraloid" (registered trademark) EXL-2 made of a butadiene / alkyl methacrylate / styrene copolymer.
655 (average primary particle size 0.2 μm; manufactured by Kureha Chemical Industry Co., Ltd.), acrylic EXL-2314 (average primary particle size 0.2 μm, manufactured by Kureha Chemical Industry Co., Ltd.), acrylic ester / methacrylic acid "Staphyloid" (registered trademark) AC-3355 (average primary particle size 0.5 μm; manufactured by Takeda Pharmaceutical Co., Ltd.) composed of an ester copolymer, F351 (average primary particle size 0) composed of acrylic rubber fine particles. .3
μm; manufactured by Nippon Zeon Co., Ltd., etc. can be used.

In the epoxy resin composition of the present invention,
In addition to the constituent elements (A), (B) and (C), other components such as low molecular weight organic compounds, oligomers, polymer compounds, organic or inorganic particles can be contained.

As the low molecular weight organic compound additive which can be blended with the epoxy resin composition of the present invention, an amide group in the molecule,
Examples include compounds having a hydrogen-bonding functional group such as a urethane group, an imide group, and a sulfonamide group, and a functional group that reacts with the epoxy resin of the constituent element (A) or the curing agent of the constituent element (B). By blending, it is possible to increase the compressive yield stress without significantly impairing the compressive yield strain of the cured resin.

Examples of such low-molecular weight organic compounds include acrylamide derivatives such as acrylamide, N, N'-dimethylacrylamide and acryloylmorpholine.

The oligomer which can be blended in the epoxy resin composition of the present invention includes polyester polyurethane having a polyester skeleton and a polyurethane skeleton, a urethane skeleton having a polyester skeleton and a polyurethane skeleton, and a urethane (meth) acrylate group at the terminal of the molecular chain ( Examples thereof include (meth) acrylates and indene-based oligomers. 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 of the constituent element (B), particularly the curing agent having active hydrogen such as amino group. .

A thermoplastic resin is preferably used as the polymer compound that can be incorporated into the epoxy resin composition 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 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 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.

In the prepreg of the present invention, the uncured epoxy resin composition, which comprises the components (A), (B) and (C) and optionally other components, is impregnated into the carbon fibers. Regarding viscoelasticity, in order to obtain good handleability of the prepreg, a measurement frequency of 0.5 Hz, 50
It is preferable that the storage elastic modulus G'at 300C 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. G'is 50000Pa
If it exceeds, the flexibility of the prepreg deteriorates, the shapeability on the curved surface becomes insufficient, and the impregnation property into the reinforcing fiber deteriorates in some cases. Such viscoelasticity
This can be achieved by optimizing the type and mixing ratio of the epoxy resin component contained in the constituent element (A), or by including the thermoplastic resin in an appropriate amount. Examples of the carbon fiber used in the present invention include acrylic-based, pitch-based and rayon-based carbon fibers. Of these, acrylic resins having high tensile strength are preferable. Further, the carbon fiber in the present invention may also include graphite fiber.

As the carbon fiber in the present invention, a carbon fiber having a high tensile elastic modulus is used so that a lightweight golf club shaft, a fishing rod and other sports equipment can exhibit sufficient rigidity with a small amount of material. preferable. Such a carbon fiber has a tensile modulus of 200 to 800 GP.
a, preferably 225 to 800 GPa, more preferably 330 to 600 GPa.

In the present invention, glass fibers, aramid fibers, boron fibers, alumina fibers, silicon carbide fibers or the like can be used in combination with carbon fibers as reinforcing fibers. 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 carbon fiber reinforced composite material, it is preferable that the carbon fiber content in the prepreg is high, and the carbon fiber content in the prepreg is 70 to 90% by weight.
Is preferable, more preferably 75 to 90% by weight, and further preferably 80 to 90% by weight or more. When the carbon fiber content is less than 70% by weight, the weight reduction effect may not be sufficient, and when the carbon fiber content exceeds 90% by weight, voids remain in the composite material due to the small amount of resin, resulting in mechanical properties. May decrease.

The carbon fiber used in the present invention is used in order to improve the adhesiveness of the epoxy resin composition with the cured resin and to further enhance the non-fiber direction compressive strength of the carbon fiber reinforced composite material. It is preferable that a compound having at least one functional group selected from an epoxy group, a hydroxyl group, an acrylate group, a methacrylate group, a carboxyl group, and a carboxylic acid anhydride group is attached to the surface of as a sizing agent. By preliminarily attaching the compound having these functional groups to the carbon fiber surface as a sizing agent,
Interaction between the functional groups on the carbon fiber surface and the functional groups in the polymer network of the resin cured product due to non-covalent bonds such as chemical bonds or hydrogen bonds, and the adhesiveness between the carbon fiber and the resin cured product is improved. Can be increased.

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

In the present invention, examples of the compound having an acrylate group or a methacrylate group that can be contained in the sizing agent 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 that can be contained in the sizing agent in the present invention include dodecenylsuccinic acid, polyadipic acid, polyazelaic acid, polysebacic acid, phthalic acid and methyltetrahydrophthalic acid. , Methylhyxahydrophthalic acid, methylhymic acid, hexahydrophthalic acid, tetrahydrophthalic acid, trimellitic acid, pyromellitic acid and their acid anhydrides.

Hereinafter, a method for producing a prepreg which can be suitably applied in the present invention, and a method for laminating the prepreg and heating and curing the prepreg to obtain a carbon fiber reinforced composite material 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 the 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, the matrix resin whose viscosity has been lowered by heating is directly impregnated into the carbon fiber, or a film in which the 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 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 used. The resin composition may be localized.

To form a carbon fiber composite material using the prepreg of the present invention, a method of laminating the prepreg and then heat-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 wrapped 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 carbon fiber composite material of the present invention can also be produced by using the above-mentioned resin composition by a method which does not pass through a prepreg.

Examples of such a method include a method of impregnating carbon fiber with the epoxy resin composition of the present invention, followed by heating and curing, that is, hand layup, resin transfer molding, SCRIMP (registered trademark), filament. A molding method such as winding, pull-through, reaction injection molding, resin film infusion, etc. can be selected and applied according to the purpose.

Among these methods, the method of preparing the epoxy resin composition by mixing the two liquids of the constituent (A) and the constituent (B) immediately before use can be preferably adopted.

[0065]

EXAMPLES The present invention will be described in detail below with reference to examples. Compression test of cured resin, prepreg production, 6 # compressive strength of composite material, production of carbon fiber composite tubular body,
The torsional strength of the tubular body was measured by the following method. (1) Compression test of cured resin product The resin composition raw materials shown in Table 1 were mixed with a kneader to obtain an epoxy resin composition in which polyvinyl formal was uniformly dissolved. The resin composition is heated to 80 ° C., defoamed with a vacuum pump, poured into a mold, and heated at 130 ° C. (Examples 1 to 5, Comparative Examples 1 to 3) or 180 ° C. (Comparative Example 4) for 90 minutes. By processing, a plate of a resin cured product having a thickness of 6 mm was produced. Then, a cubic test piece having a side length of 6 mm was cut out from the cured resin plate, and the test speed was 1 ± 0.
The compressive yield stress, the nominal strain at compressive yield, the compressive elastic modulus, and the nominal strain at compressive failure were measured at 2 mm / min under other conditions according to JIS K7181. (2) Measurement of toughness of cured resin From the cured resin plate having a thickness of 6 mm described in the previous section, a width of 12 mm,
Cut out a test piece with a length of 60 mm, ASTM D5045
According to -91, notch 3-point bending method (single edge
The fracture toughness value K _1C was measured by notched bend (SENB). (3) Preparation of prepreg The 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 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.
It was sandwiched between heated metal rolls and heated and pressed to impregnate it with the resin composition.

After impregnation, the release paper on one side is stripped from the prepreg, a polyethylene film is attached to the surface on the stripped 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. (4) The 6 # compressive strength unidirectional prepreg sheet of the fiber reinforced composite material is laminated so that the fibers are oriented in the same direction and the thickness of the laminated plate is approximately 1 mm, and the temperature is set in an autoclave. Thirteen
0 ° C (Examples 1 to 5, Comparative Examples 1 to 3) or 180 ° C
(Comparative Example 4), a unidirectional fiber-reinforced composite material was produced by heating and pressing at a pressure of 290 Pa for 2 hours for curing. The obtained unidirectional fiber-reinforced composite material was cut out so that the angle of the reinforcing fibers was 6 °, and measured according to JIS-K-7076 method.

From the thickness of the unidirectional fiber-reinforced composite material, the fiber areal weight, the fiber density, and the number of laminated plies, the fiber volume content (V
f) was calculated, and the obtained 6 ° compressive strength was converted into a value when the volume content of the reinforcing fiber was 60%. (5) Charpy impact unidirectional prepreg sheet of fiber reinforced composite material so that the fiber directions are the same, and the thickness of the laminated plate is about 3 mm (4)
In the same manner as in the above paragraph, the unidirectional fiber reinforced composite material was formed by laminating. A test piece with a width of 10 mm and a length of 80 mm is cut out and subjected to a flatwise impact with a weighing amount of 300 kg · cm, that is, an impact is applied from a direction perpendicular to the surface of the unidirectional fiber-reinforced composite material, and a Charpy impact test is performed according to JIS K-7077. went. No notch was introduced in the test piece. (6) Fabrication of tubular body made of fiber-reinforced composite material By the following operations (a) to (e), a fiber having a laminated constitution of [0 ₃ / ± 45 ₃ ] in the cylindrical axis direction and an inner diameter of 10 mm A composite tubular body was prepared. 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. (Bias material) (c) The tensile modulus of elasticity of the carbon fiber is 295 GPa and the weight of the carbon fiber is 125 so that the direction of the fiber is the longitudinal direction.
800 m in length of prepreg P2255F-12R manufactured by Toray Industries, Inc. having a g / m2 content of carbon fiber of 76% by weight.
A rectangular piece measuring m × 118 mm in width was wound so that the longitudinal direction of the prepreg and the axial direction of the mandrel coincided with each other. (Straight material) (d) Wrapping tape (heat resistant film tape) is wrapped around, and 130 ° C. in a curing oven (Examples 1 to 5, Comparative Example 1).
~ 3) or 180 ° C (Comparative Example 4), 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. (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) (Examples 1 to 5, Comparative Examples 1 to 4) The raw materials shown in Table 1 were mixed with a kneader to obtain an epoxy resin composition in which polyvinyl formal was uniformly dissolved.

Using this resin composition and the carbon fibers shown in Table 1, 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 tubular body were produced according to the method described above.

The 6 ° compressive strength and Charpy impact value of the fiber reinforced composite material were measured according to the above-mentioned method.

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

Table 1 shows the physical properties of the cured resin, the physical properties of the fiber-reinforced composite material, and the physical properties of the tubular body made of the fiber-reinforced composite material in each example.
Are shown together.

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, and has a high impact resistance. The Charpy impact value, which is an index, is also high. Further, it is understood that the tubular body formed by using the prepreg exhibits high torsional strength.

[0075]

[Table 1]

[0076]

The fiber-reinforced composite material of the present invention has excellent material strength, particularly strength against compressive stress in a direction different from the fiber direction. This has excellent impact strength,
A tubular body made of a fiber-reinforced composite material, which has also been made lightweight, can be obtained.

The tubular body made of the fiber-reinforced composite material 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 (7)

[Claims] 1. A resin cured product, which comprises the following constituent elements (A) and (B), has a compressive yield stress of 110 to 110.
140 MPa, and the nominal strain during compression yield is 6 to 1
An epoxy resin composition for a carbon fiber reinforced composite material, which is 0%. (A) Epoxy resin (B) Curing agent 2. The cured elastic resin after heat curing has a compressive elastic modulus of 2.3 to 3.5 GPa and a nominal strain at the time of compressive failure of 50% or more. Epoxy resin composition for carbon fiber reinforced composite material. 3. An epoxy resin composition for a carbon fiber reinforced composite material according to claim 1, which comprises the following constituent element (C). (C) Rubber fine particles having an average particle diameter of 2 μm or less 4. A prepreg obtained by impregnating carbon fibers with the epoxy resin composition according to claim 1. 5. An epoxy group, a hydroxyl group,
Acrylate group, methacrylate group, carboxyl group,
The prepreg according to claim 4, wherein a sizing agent having at least one functional group selected from carboxylic acid anhydride groups is attached. 6. A carbon fiber reinforced composite material comprising a cured resin product of the epoxy resin composition according to any one of claims 1 to 3 and carbon fiber. 7. An epoxy group, a hydroxyl group,
Acrylate group, methacrylate group, carboxyl group,
The carbon fiber reinforced composite material according to claim 6, wherein a compound having at least one functional group selected from carboxylic acid anhydride groups is attached as a sizing agent.