JP2002363253A - Epoxy resin composition, prepreg and fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition capable of providing a cured product having high heat resistance and high elastic modulus and low water absorption coefficient under high room temperature and under high temperature and humidity, a prepreg using the epoxy resin composition and a fiber-reinforced composite material composed of the epoxy resin composition and a reinforcing fiber. SOLUTION: The epoxy resin composition comprises the following components: (A) an epoxy resin having >=3 epoxy groups in the molecule, (B) an epoxy resin represented by a specific structural formula and (C) an aromatic diamine compound, in the skeleton, having 1-4 phenyl groups in which at least one phenyl group is a phenyl group having an amino group at meta position, and satisfies the formula I: 0.05<=y/x<=10 and the formula II: 0.7<=(x+y)/z<=1 when weights of epoxy resins of the components A and B and the component C contained in the epoxy resin composition are respectively defined as x wt.%, y wt.% and z wt.% respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an epoxy resin composition, a prepreg, and a fiber-reinforced composite material. More specifically, the present invention relates to an epoxy resin which provides a fiber-reinforced composite material which is excellent in mechanical properties of a compression system, particularly a compression system under high temperature and high humidity, and which is suitable as a structural material, a prepreg obtained therefrom, and a fiber-reinforced composite material.

[0002]

2. Description of the Related Art A polymer-based composite material comprising a reinforcing fiber and a matrix resin has been widely used for sporting goods, aerospace, general industrial use, etc. because of its light weight and excellent mechanical properties. Various methods have been used for producing the fiber-reinforced composite material, and a method using a prepreg, which is a sheet-like intermediate substrate in which an uncured matrix resin is impregnated in reinforcing fibers, is widely used. In this method, a molded product of a composite material is usually obtained by heating a plurality of prepregs after laminating a plurality of prepregs. Thermosetting resins and thermoplastic resins are both used as matrix resins for prepregs.In most cases, thermosetting resins with excellent handleability are used, and among them, epoxy resins are used most often. ing. Further, a maleimide resin, a cyanate ester resin and a combination thereof are often used.

[0003] In general, the strength and elastic modulus of a polymer material decrease under high temperature and high humidity conditions. Therefore, the physical properties such as the strength of the fiber-reinforced composite material having a polymer as a matrix are liable to decrease under high temperature and high humidity conditions. However, when the composite material is applied as a structural material for an aircraft, a vehicle, a ship, and the like, it is required that the physical properties be sufficiently maintained even under high temperature and high humidity conditions.

When a fiber-reinforced composite material is used as a structural material, compressive strength is a particularly important physical property. Compressive strength is measured by using test pieces such as non-perforated plates, perforated plates, and cylinders.In actual use, however, it is often used in the form of a plate with bolt holes. The compressive strength of the perforated plate, especially under high temperature and high humidity conditions, is important. However, although the conventional polymer-based composite material has the advantage of light weight, the compressive strength under high-temperature or high-humidity conditions may not be sufficient, and applicable applications may be limited.

In order to improve the compressive strength under high temperature and high humidity conditions, it is effective to increase the elastic modulus of the matrix resin, and it is important to suppress the decrease in the elastic modulus under high temperature and high humidity conditions. It is. Means have been proposed to improve the resin elastic modulus by making the epoxy resin have a high crosslinking density, and to suppress a decrease in the elastic modulus under high-temperature and high-humidity conditions, to reduce the water absorption.

As a resin composition having excellent heat resistance, toughness and impact strength, JP-A-63-86758 discloses tetraglycidyldiaminodiphenylmethane and a low molecular weight epoxy resin such as diglycidylaniline as a reactive diluent. And an epoxy resin composition comprising diaminodiphenyl sulfone are disclosed.

However, in a resin composition using a low-molecular-weight epoxy resin such as diglycidylaniline, 23
Although the improvement in impact strength and compressive strength at ° C. can be realized, the compressive strength under high temperature and high humidity has not been solved at all because the resin elasticity of the resin composition at high temperature and high humidity is not high.

As a resin composition having excellent compressive strength under high temperature and high humidity, WO96-17006 discloses tetraglycidyldiaminodiphenylmethane, a bifunctional epoxy resin such as a bisphenol A type epoxy resin and diglycidyl resorcinol, and a trifunctional epoxy resin. An epoxy resin composition comprising 3,3'-diaminodiphenyl sulfone is disclosed.

However, the epoxy resin composition comprising tetraglycidyldiaminodiphenylmethane and 3,3'-diaminodiphenylsulfone has an insufficient resin elasticity and a glycidyl ether type bifunctional epoxy resin such as bisphenol A epoxy resin or diglycidyl resorcinol. , The resin elastic modulus is reduced, so that the compressive strength is reduced. Therefore, further improvement in compressive strength has been required.

[0010]

DISCLOSURE OF THE INVENTION The present invention is directed to a resin composition which improves such conventional drawbacks and provides a fiber-reinforced composite material having excellent compressive strength under room temperature, high temperature and high humidity conditions, particularly, compressive strength of a perforated plate. The purpose is to provide.

[0011]

In order to solve the above problems, the epoxy resin composition of the present invention has the following constitution. That is, an epoxy resin composition comprising the following components [A], [B], and [C], wherein the content of the epoxy resin of component [A] contained in the epoxy resin composition is as follows: x weight%, the content of the epoxy resin of the component [B] is y weight%, and the content of all epoxy resins contained in the epoxy resin composition is z weight%,
An epoxy resin composition satisfying the following formulas (I) and (II). [A]: an epoxy resin having at least three or more epoxy groups in a molecule [B]: an epoxy resin represented by the following formula (III)

[0012]

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(Wherein, R _{1 to} R ₅ are each a substituent selected from hydrogen, halogen, and an alkyl group having 1 to 8 carbon atoms.) [C]: 1 to 4 phenyl groups in the skeleton Wherein at least one of the phenyl groups is a phenyl group having an amino group at the meta position, 0.05 ≦ y / x ≦ 10 (I) 0.7 ≦ (x + y ) / Z ≦ 1 (II) The prepreg according to the present invention has the following configuration. That is, it is a prepreg obtained by impregnating reinforcing fibers with the epoxy resin composition.

Further, the fiber reinforced composite material according to the present invention has the following constitution. That is, it is a fiber-reinforced composite material comprising a cured product of the epoxy resin composition and reinforcing fibers.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, in order to provide a fiber-reinforced composite material having excellent compressive strength at room temperature, high temperature and high humidity, the matrix resin has high heat resistance and high room temperature and high temperature. It is characterized by using a resin composition which gives a cured product having a low water absorption even under moisture and a high elasticity.

In the present invention, the constituent element [A] is an epoxy resin having at least three or more epoxy groups in a molecule, and is a component necessary for providing a cured product having high heat resistance. It is not preferable to have two or less epoxy groups in the molecule because it is difficult to give a cured product having sufficient heat resistance.

Specific examples of the epoxy resin having three or more epoxy groups in the molecule include, for example, a novolak type epoxy resin (an epoxy resin obtained by reacting novolak and epichlorohydrin) and tetrakis (glycidyloxyphenyl) Ethane and tris (glycidyloxy)
Examples include glycidyl ether type epoxy resins such as methane, glycidylamine type epoxy resins such as tetraglycidyl xylylenediamine, and halogen and alkyl substituted products thereof.

Of these, glycidylamine type epoxy resins selected from the following formulas (IV) and / or (V) are preferably used because they provide excellent heat resistance and elastic modulus.

[0019]

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(Wherein, R _{6 to} R ₉ are each a substituent selected from hydrogen, halogen, and an alkyl group having 1 to 8 carbon atoms.)

[0021]

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(Wherein, R _{10 to} R ₁₇ are each a substituent selected from hydrogen, halogen, and an alkyl group having 1 to 8 carbon atoms, and X ₁ is —CO—, —S—, —SO ₂ — , -O-,
Or a divalent linking group represented by any of the following formulas (VI) to (VII). )

[0023]

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(Here, R _{18 to} R ₁₉ independently represent hydrogen or an alkyl group having 4 or less carbon atoms.)

[0025]

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(Wherein R ₂₀ -R ₂₃ independently represent hydrogen, halogen or an alkyl group having 4 or less carbon atoms, X ₂ ,
X ₃ is independently -CO-, -S-, -SO _2- , -O-,
Alternatively, it represents a divalent linking group represented by the following formula (VIII). )

[0027]

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(Wherein R _{24 to} R ₂₅ independently represent hydrogen or an alkyl group having 4 or less carbon atoms). Specific examples of the formula (IV) include tetraglycidyldiaminodiphenylmethane and the like of the general formula (V). Specific examples include triglycidylaminophenol and triglycidylaminocresol.

In the present invention, in order to obtain a resin composition having excellent heat resistance and elastic modulus, 85 to 100% by weight of 100% by weight of the component [A] contained in the epoxy resin composition of the present invention. % Is the formula (IV) and / or (V)
Epoxy resin selected from the group consisting of
It is more preferable that the content be 100% by weight.

In the present invention, the component [B] is represented by the following formula (I)
It is an epoxy resin represented by II) and has a low water absorption even under high room temperature and high temperature and high humidity, and is a component necessary to give a cured product having a high elastic modulus.

[0031]

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(Wherein R _{1 to} R ₅ are each a substituent selected from hydrogen, halogen, and an alkyl group having 1 to 8 carbon atoms.) The epoxy resin represented by the general formula (III) is, for example, , Aniline or a substituent derivative thereof and epichlorohydrin, and specific examples thereof include N, N-diglycidylaniline and N, N-diglycidyl o-toluidine.

In the present invention, a bifunctional epoxy resin may be used as the epoxy resin other than the constituent element [A] and the constituent element [B]. By blending the bifunctional epoxy, the distance between the crosslinking points of the obtained cured resin can be increased, and the resin elongation and the resin toughness can be improved. For example, specific examples include bisphenol A type epoxy resin (epoxy resin obtained by reaction of bisphenol A and epichlorohydrin), bisphenol F type epoxy resin (epoxy resin obtained by reaction of bisphenol F and epichlorohydrin), Bisphenol S type epoxy resin (epoxy resin obtained by reaction of bisphenol S with epichlorohydrin) and the like can be mentioned. Bifunctional epoxy resins other than the above-mentioned components [A] and [B] can also be used according to the respective purposes. (In the present invention, a resin having one or more epoxy groups is referred to as an epoxy resin, and one epoxy group is referred to as monofunctional. For example, an epoxy resin having two epoxy groups in a molecule is referred to as a bifunctional epoxy resin. In the present invention, a bifunctional epoxy resin having a particularly large distance between two epoxy groups in the molecule, for example, a bifunctional epoxy resin having an epoxy equivalent of 350 or more can be preferably used. (Hereinafter, such a bifunctional epoxy resin will be referred to as the epoxy resin of the component [D].) The use of the epoxy resin of the component [D] not only further increases the distance between cross-linking points in the resin cured product, but also described later. When the thermoplastic resin is mixed, the compatibility between the epoxy resin and the thermoplastic resin is enhanced, and therefore, the flexural deflection, tensile elongation, and resin toughness of the cured resin are greatly improved, which is preferable.

The epoxy equivalent of the epoxy resin of the component [D] is preferably in the range of 400 to 10000, more preferably 400 to 6000. 10,000
Exceeding the range is not preferred because the heat resistance of the obtained fiber-reinforced composite material (hereinafter, referred to as composite material) may decrease, or the viscosity of the resin composition may increase, and the handling property of the prepreg may deteriorate. If it is less than 400, the effect of improving the tensile elongation and the resin toughness of the cured resin is small, which is not preferable.

The epoxy resin of the component [D] may be directly mixed with the epoxy resin of the component [A] and the component [B] using a mixer or a kneader, or the epoxy resin of the component [D] may be mixed. It may be adhered as a sizing agent for carbon fiber and blended into the epoxy resin of the component [A] and the component [B] at the time of prepreg production.

In order to provide a resin cured product having high heat resistance, low water absorption, and high elastic modulus under high room temperature and high temperature and high humidity, the constituents contained in the epoxy resin composition of the present invention [ The content of the epoxy resin of A] was x weight%, the content of the epoxy resin of component [B] was y weight%, and the content of all epoxy resins contained in the epoxy resin composition was z weight%. Then, the following equations (I) and (II)
It is necessary to satisfy

0.05 ≦ y / x ≦ 10 (I) 0.7 ≦ (x + y) / z ≦ 1 (II) where y / z is a component included in the epoxy resin composition of the present invention. The weight ratio of the epoxy resin of the component [A] to the epoxy resin of the component [B]. When this value is within the range of the formula (I), high heat resistance, low water absorption, and high room temperature And a resin composition that gives a cured resin having a high elastic modulus under high temperature and high humidity.

When y / x is smaller than 0.05, the elastic modulus of the obtained cured resin at room temperature and under high temperature and high humidity is undesirably low. On the other hand, when y / x is more than 10, not only is the water absorption of the cured resin obtained high, but also the heat resistance of the cured resin decreases, which is not preferable. Preferably, y / x is 0.1 or more and 3 or less,
More preferably, y / x is 0.1 or more and 1 or less.

(X + y) / z is the weight ratio of the epoxy resin of the component [A] and the epoxy resin of the component [B] to all the epoxy resins contained in the epoxy resin composition of the present invention. When this value is within the range of the formula (II), high heat resistance, low water absorption, and high room temperature and high temperature and high humidity are obtained by blending the component [A] and the component [B]. A resin composition that gives a cured resin having characteristics such as a high elastic modulus can be obtained.

When (x + y) / z is smaller than 0.7,
Not only does the water absorption of the cured resin increase, but also the modulus of elasticity and the heat resistance of the cured resin at room temperature and at high temperature and high humidity are reduced. Preferably, (x + y) / z is 0.
8 or more and 1 or less, more preferably (x + y) / z
Is 0.9 or more and 1 or less.

When the epoxy resin of the component [D] contained in the epoxy resin composition of the present invention is d weight%, d / z is preferably smaller than 0.25. 0.
If it is more than 25, the heat resistance of the obtained cured resin is reduced, which is not preferable. d / z is more preferably smaller than 0.15.

In the present invention, the constituent [C] is an aromatic diamine having 1 to 4 phenyl groups in the skeleton, at least one of which is a phenyl group having an amino group at the meta position. It is a compound that acts as an epoxy resin curing agent and is a necessary component to give high elastic modulus and low water absorption under high room temperature and high temperature and high humidity.

Preferred examples of the aromatic diamine compound include 3,4′-diaminodiphenyl sulfone,
Examples include 3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylether and alkyl-substituted derivatives thereof. Above all, 3,
4'-diaminodiphenylsulfone and 3,3'-diaminodiphenylsulfone can be more preferably used because of particularly long pot life. These sulfonic acid groups (—SO ₂
Those having-) weaken the reactivity of the amino group with the epoxy group due to the electrophilic effect of the sulfonic acid group, and thus have the advantage that the pot life is long. Above all, 3,3′-diaminodiphenyl sulfone is preferred in that the pot life is long and the effect of improving the compressive strength at high temperature and high humidity is most remarkably exhibited.

In the epoxy resin composition of the present invention, an aromatic diamine compound other than the component [C] may be blended. As the aromatic diamine compound other than the component [C], 4,4′-diaminodiphenylmethane,
4,4'-diaminodiphenyl sulfone and the like.

In order to provide a cured resin having a high modulus of elasticity and a low water absorption under a high room temperature and a high temperature and a high humidity, the constituents of the wholly aromatic diamine compound contained in the epoxy resin composition of the present invention are required. The aromatic diamine compound (C) is preferably contained in an amount of 50% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more.

The compounding method of these aromatic diamine compounds includes a compounding method in which the diamine compound is uniformly dissolved in the epoxy using a solvent, or a compounding method in which the compound is kneaded without using a solvent and dispersed in the epoxy resin. However, the latter compounding method is preferable because dispersing instead of dissolving has the advantage of increasing the pot life. On the other hand, when a resin film is coated or carbon fibers are impregnated in the prepreg manufacturing process, if there is a large particle size, it will be clogged between the rolls of the coating machine or will not be impregnated between the carbon fibers. The particle size of the compound is preferably 40 μm or less.

In the epoxy resin composition of the present invention,
In order to improve the curability, an epoxy resin curing agent other than the aromatic diamine compound can be blended. Aniline, o-toluidine, aromatic amines other than diamine compounds such as compounds obtained by condensing aniline with formaldehyde, aliphatic amines such as isophorone diamine,
Of imidazole derivatives, dicyandiamide, tetramethylguanidine, carboxylic anhydrides such as methylhexahydrophthalic anhydride, carboxylic acid hydrazides such as adipic hydrazide, carboxylic acid amides, polyphenol compounds, polymercaptan, and boron trifluoride ethylamine complex Such Lewis acid complexes and the like can be used.

In the present invention, an addition compound (adduct compound) having a high curing activity and obtained by reacting the epoxy resin curing agent with the epoxy resin can also be used.
In addition, those obtained by microencapsulating these curing agents are:
It is preferable from the viewpoint of increasing the storage stability of the prepreg.

In the present invention, component [C] is included,
The compounding amount of these epoxy resin curing agents is such that the number of moles of the epoxy group contained in the resin composition of the present invention is e, and the number of moles of the active hydrogen is f (calculated to include seven active hydrogens per molecule in dicyandiamide). ) And e / f
Is preferably 0.3 or more and 1.5 or less. e / f
If less than 0.3, the epoxy resin is not sufficiently cured,
It is not preferable because a cured resin having a high elastic modulus may not be obtained, and if it is more than 1.5, active hydrogen remaining unreacted and water present in the atmosphere are bonded by hydrogen bonding. However, it is not preferable because the water absorption of the cured resin may increase. e / f is 0.5 or more and 1.2
It is more preferred that:

These epoxy resin curing agents may be used in combination with a curing accelerator in order to increase the curing activity of the resin. For example, a method of combining a urea derivative or an imidazole derivative as a curing accelerator with an aromatic diamine compound or dicyandiamide, a method of combining a tertiary amine or an imidazole derivative as a curing accelerator with a carboxylic anhydride or a polyphenol compound, and the like. .

As the urea derivative, a compound obtained by reacting a secondary amine with an isocyanate, for example, 3-phenyl-1,1-dimethylurea, 3- (3,4-dichlorophenyl) -1,1-dimethylurea ( DCMU), 3
-(3-chloro-4-methylphenyl) -1,1-dimethylurea, 3-phenyl-1,1-dimethylurea, 2,
4-bis (3,3-dimethylureido) toluene, 4,
4'-methylenebis (phenyldimethylurea) and the like are preferably used.

In the present invention, optional components such as a polymer compound, organic particles, and inorganic particles can be mixed with the epoxy resin composition according to the respective purposes.

As the polymer compound, a thermoplastic resin soluble in an epoxy resin is preferably used. By blending such a thermoplastic resin, effects such as control of resin viscoelasticity, improvement in prepreg handleability, and improvement in adhesion between the matrix resin and the reinforcing fibers can be provided.

As the thermoplastic resin soluble in the epoxy resin, a thermoplastic resin having a hydrogen-bonding functional group is preferred from the viewpoint of compatibility with the epoxy resin and adhesion to the reinforcing fiber.

Examples of the hydrogen bonding functional group include an alcoholic hydroxyl group, an amide group, an imide group and a sulfonyl group. Further, as the thermoplastic resin having an alcoholic hydroxyl group, polyvinyl acetal resin such as polyvinyl formal or polyvinyl butyral, phenoxy resin, etc., as the thermoplastic resin having an amide group, polyamide, such as a thermoplastic resin having an imide group, Examples of the thermoplastic resin having a sulfonyl group such as polyimide include polysulfone. Such polyamide, polyimide and polysulfone may have a functional group such as an ether bond or a carbonyl group in the main chain, and the polyamide may have a substituent at the nitrogen atom of the amide group.

Commercially available thermoplastic resins having a hydrogen-bonding functional group include, for example, polyvinyl acetal resins such as “Denka Butyral” and “Denka Formal” (manufactured by Denki Kagaku Kogyo KK), and “Vinilec” ( Chisso Corporation), “UCAR” P as phenoxy resin
KHP (manufactured by Union Carbide), polyamide resin "Macromelt" (manufactured by Henkel Hakusui Co., Ltd.), "Amilan" CM4000 (manufactured by Toray Industries, Inc.), polyimide "Ultem" (manufactured by General Electric), " Matrimid "5218 (manufactured by Ciba) and" Sumika Excel "as polysulfone (Sumitomo Chemical Co., Ltd.)
And "UDEL" and "RADEL" (manufactured by BP Amoco) and the like.

Among these thermoplastic resins having a hydrogen-bonding functional group, polyimide and polysulfone are more preferably used in that they give a cured resin having high heat resistance and a high elastic modulus under high temperature and high humidity. Can be

In the present invention, the thermoplastic resin soluble in the epoxy resin gives the epoxy resin composition an appropriate viscoelasticity,
Since a high quality composite material can be obtained, all epoxy resin 100
1 to 50 parts by weight, preferably 1 to 25 parts by weight with respect to parts by weight
It is preferable to mix by weight.

As a method of blending the thermoplastic resin soluble in the epoxy resin, the thermoplastic resin may be dissolved in the epoxy resin in advance, or may be dispersed in the epoxy in a powder state.
It may be dissolved at the time of molding.

In the present invention, organic particles such as rubber particles and thermoplastic resin particles can be blended with the epoxy resin composition in order to increase the toughness of the resin and the impact resistance of the obtained composite material.

As the rubber particles, crosslinked rubber particles and core-shell rubber particles obtained by graft-polymerizing a heterogeneous polymer on the surface of the crosslinked rubber particles are preferably used from the viewpoint of handleability and the like.

Commercially available crosslinked rubber particles include XER-91 (manufactured by Nippon Synthetic Rubber Industries, Ltd.) comprising a crosslinked product of a carboxyl-modified butadiene-acrylonitrile copolymer.
CX-MN series (manufactured by Nippon Shokubai Co., Ltd.) and YR-500 series (manufactured by Toto Kasei Co., Ltd.) composed of acrylic rubber fine particles can be used.

Commercially available core-shell rubber particles include, for example, “Paraloid” EXL-2655 (made by Kureha Chemical Industry Co., Ltd.) made of butadiene / alkyl methacrylate / styrene copolymer, and acrylic acid ester / methacrylic acid ester. "Staphyloid" AC- consisting of a polymer
3355, TR-2122 (manufactured by Takeda Pharmaceutical Co., Ltd.),
"PARALOID" made of butyl acrylate / methyl methacrylate copolymer EXL-2611, EXL-3387 (Rohm & Haas)
Etc. can be used.

As the thermoplastic resin particles, polyamide particles and polyimide particles are preferably used. Commercially available polyamide particles include SP-500, ATOC, manufactured by Toray Industries, Inc.
"Orgasol" manufactured by HEM can be used.

In the present invention, the organic particles such as rubber particles and thermoplastic resin particles are used in an amount of 0.1 to 0.1 parts by weight based on 100 parts by weight of the total epoxy resin in order to achieve both the elastic modulus and the toughness of the obtained cured resin. The amount is preferably 30 parts by weight, more preferably 1 to 15 parts by weight.

In the present invention, inorganic particles such as silica, alumina, smectite and synthetic mica can be blended with the epoxy resin composition for controlling viscoelasticity such as thickening of the resin composition and imparting thixotropic properties.

In the present invention, since the inorganic particles impart appropriate viscoelasticity to the epoxy resin composition and a prepreg having excellent handleability and a high-quality composite material can be obtained, the entire epoxy resin 1
It is preferable to add 0.001 to 20 parts by weight, more preferably 0.01 to 10 parts by weight, based on 00 parts by weight.

The reinforcing fibers used in the present invention include:
Glass fiber, carbon fiber, graphite fiber, aramid fiber, boron fiber, alumina fiber, silicon carbide fiber and the like are preferable.
These fibers may be used in combination of two or more,
In order to obtain a lighter and more durable molded product, it is preferable to use carbon fiber or graphite fiber.

In the present invention, any kind of carbon fiber or graphite fiber can be used depending on the application. However, since a composite material having excellent impact resistance and high rigidity and mechanical strength can be obtained, The tensile modulus in the strand tensile test according to the method described in JIS R 7601 is 200
GPa or more, tensile strength 4. High strength and high elongation carbon fiber having a tensile elongation of 4% or more and a tensile elongation of 1.7% or more is most suitable.

The cross-sectional shape of the carbon fiber is not particularly limited to a conventional circular cross-section yarn.
No. 02815, JP-A-3-185121, and JP-A-3-97917, the cross-sectional shapes of which are triangular, quadrangular, hollow, multilobal, and carbon fibers having an irregular cross-section such as an H-shape. Buckling of the fiber is less likely to occur than carbon fiber having a circular cross section, and is preferably used because the resulting fiber-reinforced composite material has improved compression characteristics.

When the carbon fiber having such an irregular cross section is used, the cross section of the single fiber is a multi-lobed shape having 3 to 5 leaves, and each leaf substantially has a bulge from its root to its tip. The one in which a plurality of circles are joined is preferably used. Further, those in which the degree of irregularity defined by the ratio R 2 / r of the circumscribed circle radius R and the inscribed circle radius r of the fiber cross-sectional shape is 1.5 to 3 are more preferable because the effect of preventing buckling is large.

The form of the reinforcing fiber is not particularly limited. For example, a long fiber, a tow, a woven fabric, a mat, a knit, a braid, and the like which are aligned in one direction are used. Also,
In particular, for applications that require high specific strength and specific elastic modulus, an array in which reinforcing fibers are aligned in a single direction is most suitable, but a cross (woven) array that is easy to handle is also used. Suitable for the invention.

The prepreg of the present invention is prepared by 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 (dry method) in which the viscosity is reduced by heating and impregnated. can do.

The wet method is a method in which a reinforcing fiber is immersed in a solution of an epoxy resin composition, pulled up, and the solvent is evaporated using an oven or the like. The hot melt method is a method in which the viscosity of the epoxy resin composition is reduced by heating. By directly impregnating the reinforcing fibers with the material, or by preparing a film once coated with an epoxy resin composition on release paper or the like, and then laminating the film from both sides or one side of the reinforcing fibers, by heating and pressing This is a method of impregnating a reinforcing fiber with a resin. The hot melt method is preferable because there is substantially no solvent remaining in the prepreg.

After laminating the obtained prepregs, a method of heating and curing the resin while applying pressure to the laminate is used.
A composite according to the invention is made.

Here, as a method of applying heat and pressure, a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, an internal pressure molding method and the like are employed. Without going through a prepreg, a method in which the epoxy resin composition is directly impregnated into the reinforcing fiber and then cured by heating, for example, a hand lay-up method, a filament winding method, a pultrusion method, a resin injection molding method,
It can also be produced by a molding method such as a resin transfer molding method. In these methods, it is preferable to prepare a resin composition by mixing two liquids of a main agent composed of an epoxy resin and a curing agent immediately before use.

[0077]

The present invention will be described in more detail with reference to the following examples. The calculation of the mixing ratio, the flexural modulus of the cured resin, the amount of flexure, the measurement of heat resistance, the preparation of a prepreg,
The preparation of the composite material and the measurement of 0-degree compression strength and 90-degree tensile elongation were performed under the following conditions. In addition, unless otherwise specified, the measurement was performed in an environment of 23 ° C. and a relative humidity of 50%. A. Calculation of Mixing Ratio The epoxy resin of the component [A] contained in the epoxy resin composition was x weight%, and the epoxy resin of the component [B] was y.
% By weight, and all the epoxy resins contained in the epoxy resin composition were defined as z% by weight. Using these, y / x, (x
+ Y) / z was calculated. B. Room temperature flexural modulus of the cured resin The resin composition was heated to 80 ° C and injected into a mold.
The resin was cured in an oven at 80 ° C. for 2 hours to prepare a resin cured product plate having a thickness of 2 mm. Next, a test piece having a width of 10 mm and a length of 60 mm was cut out from the cured resin sheet, and three-point bending with a span of 32 mm was measured. The flexural modulus was determined according to JIS K7203. C. B. Flexural modulus of the cured resin under high temperature moisture absorption (hereinafter referred to as H / W) A resin cured product plate was prepared in the same manner as above, and a test piece having a width of 10 mm and a length of 60 mm was cut out from the resin cured product plate.
The test piece was immersed in boiling water for 20 hours. Thereafter, three-point bending with a span of 32 mm was measured in an oven heated to 90 ° C., and the H / W flexural modulus was determined according to JIS K7203. D. Heat resistance of cured resin B. 7m from the cured resin plate prepared in
g and taken out using a Mettler DSC at 30 ° C to 3 ° C.
The temperature was measured in a temperature range of 50 ° C. at a heating rate of 10 ° C./min, Tg was determined, and heat resistance was evaluated. E. FIG. Preparation of Prepreg An epoxy resin composition was applied on release paper using a reverse roll coater to prepare a resin film. Next, two resin films were placed on a carbon fiber “Treca” T700G (manufactured by Toray Industries, Inc.) having a tensile modulus of 240 GPa, a tensile strength of 4.9 GPa and a tensile elongation of 2.0% arranged in one direction in a sheet shape. The fibers were overlaid on both sides and impregnated with a resin by heating and pressing to prepare a unidirectional prepreg having a carbon fiber weight of 190 g / m ² and a matrix resin weight fraction of 35.5%. F. Preparation of Composite Material A predetermined number of unidirectional prepregs were laminated so that the direction of the reinforcing fiber was the same, and then molded at 180 ° C. for 2 hours at 0.59 MPa using an autoclave to obtain a plate-like body of the composite material. G. FIG. Compressed strength of perforated plate of composite material A quasi-isotropic laminate obtained by laminating and molding 16 ply prepregs in a pseudo-isotropic manner is 305 mm long and 25.4 mm wide.
Then, a hole having a diameter of 6.35 mm was formed in the center portion to form a perforated plate, and the compressive strength was measured according to BSS7260. The H / W perforated plate has a compressive strength of 72 ° C.
The test pieces immersed in warm water for 2 weeks were measured for compressive strength in an atmosphere at 82 ° C. (Examples 1 to 11) The epoxy resins of components [A] and [B] and the aromatic diamine compound of component [C] shown in Tables 1 to 3 were mixed with other resin components, and were kneaded. The resin composition was prepared by kneading.

Further, a plate-shaped resin cured product was prepared from the resin composition by the above-mentioned method, and its flexural modulus and water absorption were measured.

As shown in Tables 1 to 3, all exhibited high room temperature and H / W elastic modulus, heat resistance, and low water absorption. Next, a unidirectional prepreg was prepared using the resin compositions by the above-described method, laminated and cured to prepare a composite material, and the perforated plate compressive strength was measured.

As shown in Tables 1 to 3, all examples exhibited high room temperature and high H / W perforated plate compressive strength. (Comparative Example 1) With respect to the resin composition containing no component [C] shown in Comparative Example 1 of Table 3, the flexural modulus, water absorption, and perforated composite material of the cured resin were obtained in the same manner as in Examples 1 to 11. The plate compression strength was measured.

As shown in Table 3, the cured resin showed a high value of water absorption and low values of room temperature and H / W elastic modulus. In addition, the composite material perforated plate has a low compressive strength,
Particularly, the compression strength of the H / W perforated plate showed a low value. (Comparative Example 2) With respect to the resin compositions having (x + y) / z smaller than 0.7 shown in Comparative Example 2 of Table 3, Examples 1 to 11
In the same manner as in the above, the flexural modulus, the water absorption, and the compressive strength of the perforated plate of the composite material were measured.

As shown in Table 3, the cured resin showed a high value of water absorption and low values of room temperature and H / W elastic modulus. The compressive strength of the perforated composite plate also showed a low value. (Comparative Example 3) With respect to a resin composition having y / x greater than 10 shown in Comparative Example 3 in Table 3, the flexural modulus, water absorption, and composite perforated plate of the cured resin were obtained in the same manner as in Examples 1 to 11. The compressive strength was measured.

As shown in Table 3, the cured resin shows a high value of water absorption, low heat resistance, and when H / W elastic modulus is measured, deformation occurs before the start of measurement. I couldn't do that. For the same reason, the composite material H /
The compression strength of the W-perforated plate could not be measured. (Comparative Example 4) With respect to the resin compositions having y / x smaller than 0.05 shown in Comparative Example 4 of Table 3, the bending elastic modulus, the water absorption, and the composite material of the cured resin material were the same as in Examples 1 to 11. The perforated plate compressive strength was measured.

As shown in Table 3, the cured resin showed a high value of water absorption and a low H / W elastic modulus. Also, the composite material perforated plate had a low compressive strength, particularly a low H / W perforated plate compressive strength.

[0085]

[Table 1]

[0086]

[Table 2]

[0087]

[Table 3]

[0088]

According to the present invention, an epoxy resin composition which gives a cured product having high heat resistance and a high elastic modulus and a low water absorption under high room temperature and high temperature and high humidity, and a prepreg using the same Further, it is possible to provide a fiber-reinforced composite material having excellent compressive strength under room temperature, high temperature and high humidity conditions, particularly excellent in compressive strength of a perforated plate, comprising the epoxy resin composition and the reinforcing fibers as constituents. Such a composite material can be preferably applied to an extremely wide range of uses such as sports use, aerospace use, general industrial use, and the like.

Continued on front page F-term (reference) 4F072 AA04 AA07 AB06 AB08 AB09 AB10 AB22 AB24 AB28 AB29 AB30 AD27 AD30 AF28 AG03 AH02 AH04 AH31 AJ04 AK02 AK11 AK13 AL09 4J036 AA05 AC02 AC03 AF06 AH02 AH07 AH09 DC03 DC10 DC11

Claims (5)

[Claims] 1. The following components [A], [B] and [C]
Wherein the content of the epoxy resin of the component [A] contained in the epoxy resin composition is x weight% and the content of the epoxy resin of the component [B] is y weight %, And when the content of all epoxy resins contained in the epoxy resin composition is z weight%, the following formula:
An epoxy resin composition satisfying (I) and (II). [A]: an epoxy resin having at least three or more epoxy groups in a molecule [B]: an epoxy resin represented by the following formula (III): (Wherein, R _{1 to} R ₅ are each a substituent selected from hydrogen, halogen, and an alkyl group having 1 to 8 carbon atoms.) [C]: having 1 to 4 phenyl groups in the skeleton An aromatic diamine compound in which at least one of the phenyl groups is a phenyl group having an amino group at the meta position 0.05 ≦ y / x ≦ 10 (I) 0.7 ≦ (x + y) / z ≤1 ... (II) 2. Of 100% by weight of component [A] contained in the epoxy resin composition, 85 to 100% by weight is represented by the following formula:
The epoxy resin composition according to claim 1, which is an epoxy resin selected from (IV) and / or (V). Embedded image (Wherein, R _{6 to} R ₉ are each a substituent selected from hydrogen, halogen, and an alkyl group having 1 to 8 carbon atoms.) (Wherein, R ₁₀ to R ₁₇ are each hydrogen, halogen, a substituent selected from an alkyl group having 1 to 8 carbon atoms, X ₁
Is -CO -, - S -, - SO 2 -, - O-, or a divalent linking group represented by any one of the following formulas (VI) without (VII). ) (In the formula, R _{18 to} R ₁₉ are each independently hydrogen or an alkyl group having 4 or less carbon atoms.) (Wherein, R _{20 to} R ₂₃ are each independently hydrogen, halogen or an alkyl group having 4 or less carbon atoms, and X ₂ and X ₃ are each independently-
CO -, - S -, - SO 2 -, - O-, or the following formula (VI
It is a divalent linking group represented by II). ) (In the formula, R _{24 to} R ₂₅ are each independently hydrogen or an alkyl group having 4 or less carbon atoms.) 3. The epoxy resin composition according to claim 1, wherein component [C] is 3,3′-diaminodiphenylsulfone and / or 3,4′-diaminodiphenylsulfone. 4. A prepreg characterized by impregnating reinforcing fibers with the epoxy resin composition according to claim 1. 5. A fiber reinforced composite material comprising a cured product of the epoxy resin composition according to claim 1, and a reinforcing fiber.