JP2003026768A - Epoxy resin composition, prepreg, and fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition which gives a cured item having a high heat resistance and exhibiting a high modulus under high- temperature high-humidity conditions; a prepreg prepared by using the same; and a fiber-reinforced composite material comprising a fibrous reinforcement and the cured resin composition. SOLUTION: The epoxy resin composition contains (A) an epoxy resin having at leant three epoxy groups, (B) an epoxy resin represented by formula (III) (wherein R1 to R5 are each H, a halogen or a 1-8C alkyl), and (C) an aromatic diamine which has one to four phenyl groups in the backbone and two phenyl groups having amino groups-at the p-positions. The prepreg is prepared by impregnating a fibrous reinforcement with the resin composition. The fiber- reinforced composite material comprises a fibrous reinforcement and the cured resin composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD 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 composition which is excellent in the mechanical properties of a compression system, particularly the mechanical properties of a compression system under high temperature conditions, and provides a fiber-reinforced composite material suitable as a structural material, a prepreg obtained therefrom, and a fiber-reinforced composite material.

[0002]

2. Description of the Related Art Polymer-based composite materials composed of reinforcing fibers and a matrix resin are lightweight and have excellent mechanical properties, and are therefore widely used for sports equipment, aerospace applications, general industrial applications and the like. Various methods are used for manufacturing the fiber-reinforced composite material, but a method using a prepreg, which is a sheet-shaped intermediate base material in which reinforcing fibers are impregnated with an uncured matrix resin, is widely used. In this method, a molded article of a composite material is usually obtained by laminating a plurality of prepregs and then heating them. As the matrix resin used for the prepreg, both thermosetting resins and thermoplastic resins are used, but in most cases, thermosetting resins with excellent handleability are used, and among them, epoxy resins are the most used. ing. Further, a maleimide resin, a cyanate ester resin and a combination thereof are also often used.

[0003] In general, polymer-based materials have low strength and elastic modulus under high temperature and high humidity conditions. Therefore, the physical properties such as strength of the fiber-reinforced composite material using the polymer as a matrix are likely to be deteriorated under high temperature conditions. However, when the composite material is applied as a structural material for an aircraft, especially as a structural material around a jet engine, it is required to sufficiently retain the physical properties even under high temperature and high humidity conditions.

Compressive strength is a particularly important physical property when a fiber-reinforced composite material is used as a structural material. However, a conventional composite material using a polymer as a matrix has the advantage of being lightweight, but the compressive strength under high temperature and high humidity conditions may not be sufficient, which may limit the applicable applications.

In order to improve the compressive strength under high temperature and high humidity conditions, it is effective to improve the elastic modulus and heat resistance of the matrix resin, and further, it is possible to suppress the decrease in the elastic modulus under high temperature and high humidity conditions. is important. And in order to improve the resin elastic modulus, the epoxy resin has a high crosslink density,
In order to suppress the decrease in elastic modulus under high temperature conditions, measures such as improving the glass transition point have been proposed.

As a resin composition excellent in heat resistance, toughness and impact strength, Japanese Patent Laid-Open No. 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 diglycidyl aniline, 23
Although it is possible to improve impact strength and compressive strength at 0 ° C., since the heat resistance of the resin composition is not high, the compressive strength under high temperature and high humidity has not been solved at all.

As a resin composition having excellent compressive strength at high temperature, WO 96-17006 discloses tetraglycidyl diaminodiphenylmethane and a bifunctional epoxy resin such as bisphenol A type epoxy resin or diglycidyl resorcinol, and 3,3. An epoxy resin composition comprising'-diaminodiphenyl sulfone is disclosed.

However, the epoxy resin composition comprising tetraglycidyldiaminodiphenylmethane and 3,3'-diaminodiphenylsulfone is not sufficient in resin elasticity and heat resistance, and bisphenol A epoxy resin and glycidyl ether type 2 such as diglycidyl resorcinol are used. The compounding of the functional epoxy resin lowers the resin elastic modulus and the heat resistance, resulting in a decrease in the compression strength. Therefore, further improvement in compressive strength has been demanded.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a resin composition which improves the above-mentioned conventional defects and provides a fiber reinforced composite material having excellent compressive strength under high temperature and high humidity conditions.

[0011]

In order to solve such problems, the epoxy resin composition of the present invention has the following constitution. That is, an epoxy resin composition containing at least the following constituents [A], [B], and [C], wherein constituent [A] included in the epoxy resin composition:
When the content of the epoxy resin of the above is x% by weight, the content of the epoxy resin of the component [B] is y% by weight, and the content of all the epoxy resins contained in the epoxy resin composition is z% by weight, An epoxy resin composition satisfying the following formulas (I) and (II). [A]: Epoxy resin having at least 3 epoxy groups in the molecule [B]: Epoxy resin represented by the following formula (III)

[0012]

[Chemical 7]

(In the formula, 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 And an aromatic diamine compound having two phenyl groups having an amino group at the para position 0.05 ≦ y / x ≦ 10 (I) 0.7 ≦ (x + y) / z ≦ 1 ... (II) Further, the present invention has the following configuration. That is, it is a prepreg obtained by impregnating reinforcing fibers with the epoxy resin composition.

Furthermore, the present invention has the following configuration. That is, it is a fiber-reinforced composite material comprising a cured product of the epoxy resin composition and a reinforcing fiber.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In order to provide a fiber reinforced composite material having excellent compressive strength under high temperature and high humidity conditions, the present invention has high heat resistance as a matrix resin and has a high elastic modulus under high temperature and high humidity. It is characterized by using a resin composition which gives a high cured product.

In the resin composition of the present invention, the constituent element [A] is an epoxy resin having at least 3 epoxy groups in the molecule, and is a component necessary to give a cured product having high heat resistance. . It is not preferable to have two or less epoxy groups in the molecule because it becomes 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, novolac type epoxy resin (epoxy resin obtained by reaction of novolac and epichlorohydrin) and tetrakis (glycidyloxyphenyl). Ethane and tris (glycidyloxy)
Examples thereof include glycidyl ether type epoxy resins such as methane, glycidyl amine type epoxy resins such as tetraglycidyl xylylenediamine, and halogen and alkyl substitution products thereof.

Among these, a glycidyl amine type epoxy resin selected from the following formulas (IV) and / or (V) is preferably used because it gives excellent heat resistance and elastic modulus.

[0019]

[Chemical 8]

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

[0021]

[Chemical 9]

(In the formula, 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-,
Alternatively, it represents a divalent linking group represented by any of the following formulas (VI) to (VII). )

[0023]

[Chemical 10]

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

[0025]

[Chemical 11]

(Wherein R _{20 to} R ₂₃ independently represent hydrogen, halogen or an alkyl group having 4 or less carbon atoms, and 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]

[Chemical 12]

(Here, 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. Examples thereof include triglycidyl aminophenol and triglycidyl aminocresol.

In the present invention, in order to obtain a resin composition having excellent heat resistance and elastic modulus, 85 to 10 of the component [A] contained in the epoxy resin composition of the present invention is used.
0% by weight is preferably an epoxy resin selected from the formulas (IV) and / or (V), more preferably 90 to 100% by weight. If it is less than 85% by weight, excellent heat resistance and elastic modulus cannot be obtained, which is not preferable.

In the resin composition of the present invention, the constituent element [B] is an epoxy resin represented by the following formula (III), which is a component necessary to give a cured product having a high elastic modulus.

[0031]

[Chemical 13]

(In the formula, 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 formula (III) is, for example, It can be obtained by a reaction of aniline or a substituent derivative thereof with epichlorohydrin, and specific examples thereof include N, N-diglycidylaniline and N, N-diglycidyl o-toluidine.

In the resin composition of the present invention, as the epoxy resin other than the constituent element [A] and the constituent element [B], 2
Functional epoxy resins can also be used. By blending the bifunctional epoxy, it is possible to increase the distance between the cross-linking points of the obtained resin cured product and improve the resin elongation and resin toughness. 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), Examples thereof include bisphenol S type epoxy resin (epoxy resin obtained by reaction of bisphenol S and epichlorohydrin). The above-mentioned components [A] and [B]
Other bifunctional epoxy resins can also be used according to each purpose. 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 an epoxy resin of the constituent element [D].) When the epoxy resin of the constituent element [D] is used, not only the distance between the cross-linking points in the cured resin becomes further, but also described later. When a thermoplastic resin is blended, the compatibility between the epoxy resin and the thermoplastic resin is enhanced, and therefore the flexural bending amount, the tensile elongation, and the resin toughness of the cured resin are greatly improved, which is preferable.

The epoxy equivalent of the epoxy resin of the constituent [D] is preferably in the range of 400 to 10,000, more preferably 400 to 6000. 10,000
If it exceeds, the heat resistance of the obtained fiber reinforced composite material (hereinafter referred to as composite material) may be lowered, the viscosity of the resin composition may be increased, and the handleability of the prepreg may be deteriorated, which is not preferable. If it is less than 400, the effect of improving the tensile elongation and resin toughness of the cured resin is small, which is not preferable.

The epoxy resin of the constituent [D] may be blended directly with the epoxy resin of the constituent [A] and the constituent [B] by a mixer or a kneader, or the epoxy resin of the constituent [D] may be blended. You may make it adhere as a sizing agent of carbon fiber, and may mix | blend with the epoxy resin of a component [A] and a component [B] at the time of prepreg preparation.

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

0.05 ≦ y / x ≦ 10 (I) 0.7 ≦ (x + y) / z ≦ 1 (II) y / z is a constituent contained in the epoxy resin composition of the present invention. It is the weight mixing ratio of the epoxy resin of the element [A] and the epoxy of the constituent element [B]. By having this value within the range of the formula (I), high heat resistance and high elastic modulus under high temperature and high humidity are obtained. It is possible to obtain a resin composition that gives a resin cured product having.

When y / x is smaller than 0.05, the elastic modulus of the obtained resin cured product at room temperature and high temperature and high humidity becomes small, which is not preferable. Further, if y / x is larger than 10, heat resistance of the obtained resin cured product is deteriorated, which is not preferable. Y / x is preferably 0.1 or more and 3 or less, and more preferably y / x is 0.1 or more and 1 or less.

Further, (x + y) / z is the weight ratio of the epoxy resin of the constituent [A] and the epoxy resin of the constituent [B] to all the epoxy resins contained in the epoxy resin composition of the present invention. Since this value is within the range of the formula (II), it has characteristics such as high heat resistance and high elastic modulus under high temperature and high humidity due to the incorporation of the constituent element [A] and the constituent element [B]. A resin composition that gives a cured resin product can be obtained.

When (x + y) / z is smaller than 0.7,
This is not preferable because the resin cured product has reduced elastic modulus under high temperature and high humidity and heat resistance. Preferably (x + y) / z is 0.8
It is 1 or more and 1 or less, and more preferably (x + y) / z is 0.9 or more and 1 or less.

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

In the present invention, the constituent element [C] is an aromatic diamine compound having 1 to 4 phenyl groups in the skeleton and two phenyl groups having an amino group at the para position, and is cured with an epoxy resin. It is a component required to act as an agent and give a cured resin product having high heat resistance.

Preferred examples of such aromatic diamine compounds include 4,4'-diaminodiphenyl sulfone, 4,
4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylthioether, and alkyl-substituted derivatives thereof. Among them, 4,4'-diaminodiphenyl sulfone is more preferably used because it has a particularly long pot life.
Those having a sulfonic acid group (—SO ₂ —) have an advantage that the pot life is long because the reactivity of the amino group with the epoxy group is weakened by the electrophilic effect of the sulfonic acid group.

The epoxy resin composition of the present invention may contain an aromatic diamine compound other than the constituent element [C]. As the aromatic diamine compound other than the component [C], 3,3′-diaminodiphenylmethane,
3,3'-diaminodiphenyl sulfone and the like can be mentioned.

In order to give a resin cured product having high heat resistance, the aromatic diamine compound of the constituent element [C] is more than 50% by weight in the wholly aromatic diamine compound contained in the epoxy resin composition of the present invention. Preferably included,
The content is more preferably 80% by weight or more, and further preferably 90% by weight or more.

The compounding method of these aromatic diamine compounds includes a compounding method of uniformly dissolving the diamine compound in the epoxy using a solvent, or a compounding method of kneading without using a solvent and dispersing in the epoxy resin. However, the latter compounding method is preferable because there is an advantage that the pot life is longer when the particles are dispersed rather than dissolved. On the other hand, when coating a resin film or impregnating carbon fibers in the prepreg manufacturing process, if there is a large particle size, the rolls of the coating machine will be clogged and the carbon fibers will not be impregnated. The particle size of the compound is preferably 40 μm or less.

Further, in the epoxy resin composition of the present invention,
To improve the curability, an epoxy resin curing agent other than the aromatic diamine compound can be added. Aromatic amines other than diamine compounds such as aniline, o-toluidine, and compounds obtained by condensing aniline with formaldehyde, aliphatic amines such as isophoronediamine,
Imidazole derivatives, dicyandiamide, carboxylic acid anhydrides such as tetramethylguanidine, methylhexahydrophthalic anhydride, carboxylic acid hydrazides such as adipic acid hydrazide, carboxylic acid amides, polyphenol compounds, polymercaptans, boron trifluoride ethylamine complex Such Lewis acid complex and the like can be used.

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

In the present invention, including the constituent element [C],
The mixing amount of these epoxy resin curing agents is calculated such that the number of moles of epoxy groups contained in the resin composition of the present invention is e and the number of moles of active hydrogen is f (in dicyandiamide, seven active hydrogens are contained in one molecule). ), E / f
Is preferably 0.3 or more and 1.5 or less. e / f
Is less than 0.3, the epoxy resin does not cure sufficiently,
This is not preferable because a cured resin product having a high elastic modulus may not be obtained, and when it is larger than 1.5, active hydrogen remaining without reaction and water present in the atmosphere are bonded by hydrogen bonds. However, the water absorption of the cured resin may increase, which is not preferable. e / f is 0.5 or more and 1.2
The following is more preferable.

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

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, the epoxy resin composition may be blended with optional components such as polymer compounds, organic particles and inorganic particles according to their 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 of handleability of the prepreg, or improvement of adhesion between the matrix resin and the reinforcing fiber can be imparted.

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

Examples of the hydrogen-bonding functional group include alcoholic hydroxyl group, amide group, imide group and sulfonyl group. Further, as the thermoplastic resin having an alcoholic hydroxyl group, polyvinyl acetal resin such as polyvinyl formal and polyvinyl butyral, phenoxy resin, and the like, as the thermoplastic resin having an amide group, polyamide, etc., as the thermoplastic resin having an imide group, Examples of the thermoplastic resin having a sulfonyl group such as polyimide include polysulfone. The 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 hydrogen-bonding functional groups include, for example, polyvinyl acetal resins such as "Denka Butyral" and "Denka Formal" (manufactured by Denki Kagaku Kogyo KK), "Vinilec" ( Chisso Co., Ltd., as a phenoxy resin, "UCAR" P
KHP (manufactured by Union Carbide Co.), polyamide resin "Macromelt" (manufactured by Henkel Hakusui Co., Ltd.), "Amilan" CM4000 (manufactured by Toray Co., Ltd.), polyimide "Ultem" (manufactured by General Electric Company), " Matrimid "5218 (manufactured by Ciba)," Sumika Excel "as polysulfone (Sumitomo Chemical Co., Ltd.)
"Made", "UDEL", "RADEL" (made by BP Amoco), etc. can be used.

Among these thermoplastic resins having hydrogen-bonding functional groups, polyimide and / or polysulfone are more preferable because they give a resin cured product having high heat resistance and high elastic modulus under high temperature and high humidity. It is preferably used.

In the present invention, the thermoplastic resin soluble in the epoxy resin gives the epoxy resin composition proper viscoelasticity,
100% total epoxy resin to obtain high quality composite materials
The amount is preferably 1 to 70 parts by weight, more preferably 5 to 40 parts by weight with respect to parts by weight.

As a method for blending the thermoplastic resin soluble in the epoxy resin, it 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, in order to improve the toughness of the resin and the impact resistance of the resulting composite material, rubber particles or organic particles such as thermoplastic resin particles can be blended in the epoxy resin composition.

As the rubber particles, crosslinked rubber particles or core-shell rubber particles obtained by graft-polymerizing a different type of 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 Japan Synthetic Rubber Industry Co., Ltd.), which is a crosslinked product of a carboxyl-modified butadiene-acrylonitrile copolymer.
CX-MN series (manufactured by Nippon Shokubai Co., Ltd.), YR-500 series (manufactured by Toto Kasei Co., Ltd.) and the like made of acrylic rubber fine particles can be used.

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

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

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

In the present invention, in order to control viscoelasticity such as thickening of the resin composition and impart thixotropy, inorganic particles such as silica, alumina, smectite and synthetic mica can be blended with the epoxy resin composition.

In the present invention, since the inorganic particles give the epoxy resin composition an appropriate viscoelasticity, and a prepreg having excellent handleability and a good quality composite material are obtained, the total epoxy resin 1
The amount is preferably 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.
Two or more kinds of these fibers may be mixed and used,
In order to obtain a molded product that is lighter and has higher durability, it is preferable to use carbon fiber or graphite fiber.

In the present invention, all kinds of carbon fibers and graphite fibers can be used depending on the application, but since a composite material having excellent impact resistance, high rigidity and mechanical strength can be obtained, Tensile elastic modulus in the strand tensile test by the method described in JIS R 7601 is 200.
GPa or more, tensile strength 4. High strength and high elongation carbon fibers having a tensile elongation of 4% or more and a tensile elongation of 1.7% or more are most suitable.

The cross-sectional shape of the carbon fiber is not particularly limited, but it is disclosed in JP-A-4-202815 and JP-A-3.
-185121 and Japanese Unexamined Patent Publication (Kokai) No. 3-97917 have a cross-sectional shape such as a triangle, a quadrangle, a hollow, a multileaf, and an H-shaped modified cross-section carbon fiber as compared with a circular cross-section carbon fiber. Therefore, the fibers are less likely to buckle and the compression characteristics of the obtained fiber-reinforced composite material are improved, so that it is preferably used.

When the carbon fiber having such an irregular cross section is used, the cross sectional shape of the single fiber is a multilobe shape of 3 to 5 leaves, and each leaf has a bulge once from its root to its tip. A shape in which a plurality of circles are joined can be preferably used. Further, from the viewpoint of preventing buckling, it is more preferable to use one having a degree of deformation of 1.5 to 3 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. You can

The form of the reinforcing fibers is not particularly limited, and for example, long fibers aligned in one direction, tows, woven fabrics, mats, knits, braids, etc. are used. Also,
In particular, the arrangement in which the reinforcing fibers are aligned in a single direction is most suitable for applications that require high specific strength and specific elastic modulus, but a cloth (fabric) arrangement that is easy to handle is also recommended. Suitable for 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 its viscosity and then impregnated, and a hot melt method (dry method) in which it is reduced in viscosity by heating and impregnated. can do.

The wet method is a method in which the reinforcing fibers are immersed in a solution of the epoxy resin composition, then pulled up and the solvent is evaporated using an oven or the like. The hot melt method is an epoxy resin composition whose viscosity is reduced by heating. By directly impregnating the reinforcing fiber with the product, or by once forming a film by coating the epoxy resin composition on the release paper etc., then stacking the film from both sides or one side of the reinforcing fiber, and by heating and pressing This is a method of impregnating a reinforcing fiber with a resin. According to the hot melt method, the solvent remaining in the prepreg is substantially eliminated, which is preferable.

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

Here, as the 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 adopted. The fiber reinforced composite material of the present invention is After the epoxy resin composition is directly impregnated into the reinforcing fiber without using a prepreg, a method of heat curing, for example, a hand layup 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.

[0078]

The present invention will be described in more detail with reference to the following examples. Incidentally, the calculation of the compounding ratio, the flexural modulus of the cured resin, the flexural amount, the measurement of heat resistance, the production of prepreg,
Preparation of the composite material, measurement of 0-degree compressive strength, and 90-degree tensile elongation were performed under the following conditions. Moreover, unless otherwise specified, the measurement was performed in an environment of 23 ° C. and a relative humidity of 50%. A. Calculation of blending ratio x% by weight of the epoxy resin of the constituent element [A] and y of the epoxy resin of the constituent element [B] contained in the epoxy resin composition.
% By weight, and all epoxy resins contained in the epoxy resin composition were defined as z% by weight. Using these, y / x, (x
+ Y) / z was calculated. B. The flexural modulus resin composition of the cured resin product under high temperature and high humidity conditions (hereinafter referred to as H / W) is heated to 80 ° C. and poured into a mold, and 1
The plate 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 plate, and the test piece was immersed in boiling water for 20 hours. Then, in an oven heated to 90 ° C., a three-point bend with a span of 32 mm was measured, and J
The H / W flexural modulus was determined according to IS K7203. C. Heat resistance of cured resin B. 7m from the cured resin plate prepared in
g, using a DSC manufactured by METTLER CORPORATION, 30 ° C. to 3
The heat resistance was evaluated by measuring the temperature range of 50 ° C. at a temperature rising rate of 10 ° C./min to determine Tg. D. Preparation of prepreg The epoxy resin composition was applied onto release paper using a reverse roll coater to prepare a resin film. Next, two resin films were carbonized on a carbon fiber “Torayca” T700G (manufactured by Toray Industries, Inc.) having a tensile elastic modulus of 240 GPa, a tensile strength of 4.9 GPa and a tensile elongation of 2.0% arranged in a sheet shape in one direction. A unidirectional prepreg was prepared by stacking the fibers on both sides and impregnating them with a resin by heating and pressing to give a carbon fiber weight of 190 g / m ² and a matrix resin weight fraction of 35.5%. E. Preparation of Composite Material A predetermined number of unidirectional prepregs were laminated so that the directions of the reinforcing fibers were the same, and then molded using an autoclave at 180 ° C. for 2 hours at a gauge pressure of 0.59 MPa to obtain a composite material plate-shaped body. F. A laminated plate obtained by laminating and molding 6-ply unidirectional H / W compressive strength prepreg of the composite material was cut into a length of 79.4 mm and a width of 12.7 mm.
Then, after leaving for 2 weeks in a constant temperature and humidity chamber maintained at 70 ° C and relative humidity of 85%, 130 ° C according to ASTM D695.
The compressive strength was measured under the atmosphere. (Examples 1 to 4) The epoxy resin of the constituent elements [A] and [B] and the aromatic diamine compound of the constituent element [C] shown in Table 1 were mixed with other resin components and kneaded with a kneader. To prepare a resin composition.

Further, a plate-like body of a resin cured product was prepared from this resin composition by the above-mentioned method, and its H / W flexural modulus and heat resistance were measured.

As shown in Table 1, all showed high H / W flexural modulus and heat resistance. Next, using these resin compositions, a unidirectional prepreg was produced by the method described above, and these were laminated and cured to produce a composite material, and the composite material H / W compressive strength was measured.

As shown in Table 1, all of the examples showed high composite H / W compressive strength. (Comparative Example 1) With respect to the resin composition not containing the constituent element [C] shown in Comparative Example 1 in Table 1, the H / W flexural modulus, the heat resistance, and the composite of the resin cured product were the same as in Examples 1 to 4. Material H
/ W compressive strength was measured.

As shown in Table 1, the cured resin products showed low heat resistance and low H / W elastic modulus. Moreover, the composite material H / W compressive strength also showed a low value.

[0083]

[Table 1]

[0084]

According to the present invention, an epoxy resin composition which gives a cured product having high heat resistance and a high elastic modulus under high temperature and high humidity conditions, and a prepreg using the same,
Furthermore, it is possible to provide a fiber-reinforced composite material having a cured product of the epoxy resin composition and a reinforcing fiber as constituent elements and having excellent compressive strength under high temperature and high humidity conditions. Such a composite material can be preferably applied to an extremely wide range of applications such as sports applications, aerospace applications, and general industrial applications.

Continued front page    F-term (reference) 4F072 AA04 AA07 AB06 AB08 AB09                       AB10 AB22 AB24 AB28 AB29                       AD30 AD31 AE01 AF28 AG03                       AG17 AH02 AH21 AK05 AK14                       AL01 AL04 AL11 AL16 AL17                 4J036 AA05 AB12 AH02 AH07 AH13                       DB06 DB21 DC03 DC10 DC14                       DC19 DC25 DC26 DC31 DC35                       DC40 DC41 DD02 JA11

Claims (5)

[Claims] 1. The following components [A], [B], and [C]:
An epoxy resin composition comprising at least:
The content of the epoxy resin of the constituent [A] contained in the epoxy resin composition is x% by weight, the content of the epoxy resin of the constituent [B] is y% by weight, and all the components contained in the epoxy resin composition are contained. An epoxy resin composition characterized by satisfying the following formulas (I) and (II) when the content of the epoxy resin is z% by weight. [A]: Epoxy resin having at least 3 epoxy groups in the molecule [B]: Epoxy resin represented by the following formula (III): (In the formula, 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 , Aromatic diamine compound having two phenyl groups having an amino group at the para position 0.05 ≦ y / x ≦ 10 (I) 0.7 ≦ (x + y) / z ≦ 1 (II) 2. The epoxy resin composition according to claim 1, wherein 85 to 100% by weight of the constituent [A] is an epoxy resin selected from the following formulas (IV) and / or (V). . [Chemical 2] (In the formula, R _{6 to} R ₉ are each a substituent selected from hydrogen, halogen, and an alkyl group having 1 to 8 carbon atoms.) (In the formula, each of R _{10 to} R ₁₇ is 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 one of the following formulas (VI) without (VII). ) [Chemical 4] (In the formula, R _{18 to} R ₁₉ are independently hydrogen or an alkyl group having 4 or less carbon atoms.) (In the formula, R _{20 to} R ₂₃ are independently hydrogen, halogen or an alkyl group having 4 or less carbon atoms, and X ₂ and X ₃ are independently-
CO -, - S -, - SO 2 -, - O-, or the following formula (VI
It is a divalent linking group represented by II). ) [Chemical 6] (In the formula, R _{24 to} R ₂₅ are independently hydrogen or an alkyl group having 4 or less carbon atoms.) 3. The epoxy resin composition according to claim 1, wherein the constituent element [C] is 4,4′-diaminodiphenyl sulfone. 4. A prepreg obtained by impregnating reinforcing fiber 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.