JPH11302412A - Prepreg and fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a prepreg capable of being cured by usual heating, having an excellent life, tack property, and drapability, and also giving an excellent heat resistance, water resistance, and adhesion, by using essential components of (A) an epoxy resin contg. a glycidyl amine-type epoxy resin, (B) dicyan diamide, (C) an adduct of an imidazole to an epoxy resin, and (D) a carbon fiber. SOLUTION: Component A contains 50 pts.wt. or more of a glycidyl amine- type epoxy resin (epoxy equivalent, 90-180) in 100 pts.wt. of an epoxy resin. Component B is a particular compd. (average particle dia., 10 μm or less), is insoluble in the epoxy resin at 25 deg.C, but becomes soluble to react as a hardener when heated up to 100 deg.C. Component C has an m.p. of 90-130 deg.C and an average particle dia. of 10 μm or less. Component D to be used has a tensile strength of 4,000 MPa or more. A blend ratio is 2-10 pts.wt. of component B and 1-15 pts.wt. of component C based on 100 pts.wt. of component A. A curing condition can be in a temp. range of 80-110 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepreg obtained by impregnating a resin composition with a reinforcing fiber and a fiber-reinforced composite material obtained by laminating the prepreg.

[0002]

2. Description of the Related Art A prepreg currently used for structural materials such as aircraft is obtained by impregnating reinforcing fibers with an uncured matrix resin. As the uncured matrix resin, an epoxy resin and its curing agent are mainly used because the cured matrix resin (hereinafter, also referred to as a cured matrix resin) has good heat resistance, water resistance, rigidity, and the like. Epoxy resin compositions are mainly used. The curing temperature of such an epoxy resin composition is determined by the curing agent used.

At present, diaminodiphenyl sulfone (hereinafter, referred to as DD) is used as a curing agent for epoxy resins in aircraft prepregs because a cured product having excellent rigidity can be obtained.
S) is widely used. However, when this curing agent is used, it must be cured under heating conditions of 180 ° C. for about 2 hours. For this reason, for example, 100 ° C.
If a composition that is cured by heating for about 2 hours and the rigidity of the cured product remains the same as before is found, the energy required for molding can be significantly reduced. Attempts to achieve these objects include curing with imidazole derivatives as described in JP-A-4-506536. The imidazole derivative has high reactivity with the epoxy resin, and is sufficiently cured by heating at 100 ° C. for about 2 hours. However, there is a problem that the compressive strength of the composite material becomes insufficient because the adhesiveness between the cured matrix resin and the carbon fiber is low.

[0004] As another attempt, Japanese Patent Application Laid-Open No. 6-206860 has been proposed.
As described in the publication, curing with a diaminodiphenylsulfone derivative may be mentioned. When a DDS derivative is used, the adhesiveness between the cured matrix resin and the carbon fiber is generally high. However, this curing agent has low reactivity with the epoxy resin, and it is difficult to cure it by heating at 100 ° C. for about 2 hours, like DDS.

[0005] That is, an epoxy resin composition which is excellent in both the rigidity of the cured product and the adhesion to carbon fibers and which can be cured under heating conditions of 100 ° C for about 2 hours has not been found so far. Therefore, realization of such a composition has been eagerly desired.

[0006]

SUMMARY OF THE INVENTION
It cures sufficiently by heating for about 2 hours,
Excellent draping property, after curing, heat resistance, water resistance, prepreg capable of giving a fiber-reinforced composite material with excellent adhesion between the reinforcing fiber and the cured matrix resin,
And to provide such a fiber-reinforced composite material.

[0007]

In order to solve the above problems, a prepreg of the present invention has the following configuration. That is, the following components [A], [B], [C] and [D]
Prepreg.

[A] Epoxy resin containing glycidylamine type epoxy resin [B] Dicyandiamide [C] Adduct of imidazole compound and epoxy compound [D] Carbon fiber Further, in order to solve the above problems, the fiber reinforced composite of the present invention is used. The material has the following configuration. That is, it is a fiber-reinforced composite material obtained by laminating the above prepreg.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin as the component [A] in the present invention contains a glycidylamine type epoxy resin as an essential component. Epoxy resin 10 of component [A]
The glycidylamine type epoxy resin is preferably contained in 0 parts by weight, preferably at least 50 parts by weight, more preferably at least 70 parts by weight. If the amount is less than 50 parts by weight, the adhesion between the cured product and the carbon fiber tends to be insufficient.

The glycidylamine type epoxy resin is obtained by reacting amines with epichlorohydrin. When a glycidylamine-type epoxy resin is used as an essential component, the adhesiveness between the carbon fiber and the cured matrix resin becomes particularly good. Even if the rigidity of the cured product is high, if the adhesion between the fiber and the cured product is low, water will penetrate into the interface between the fiber and the cured product when immersed in water. As a result, the compressive strength of the composite material after absorbing water tends to be insufficient. However, when a glycidylamine type epoxy resin is used, such a concern is small. As the glycidylamine-type epoxy resin, tetraglycidyldiaminodiphenylmethane is preferably used because of its excellent heat resistance, water resistance and adhesiveness.

The epoxy equivalent of the glycidylamine type epoxy resin is preferably in the range of 90 to 180. When the epoxy equivalent is 90 or less, the crosslink density becomes too high, and the toughness of the cured product tends to be insufficient. On the other hand, when the epoxy equivalent is 180 or more, the crosslink density of the cured product becomes too low, and the rigidity of the cured product tends to be insufficient.

The epoxy resin as the component [A] in the present invention may contain another epoxy resin in addition to the glycidylamine type epoxy resin. Epoxy resins other than the glycidylamine type epoxy resin include tetraglycidyl ether type epoxy resin (epoxy resin having tetraphenol as a precursor), triglycidyl ether type epoxy resin (epoxy resin having triphenol as a precursor), cresol novolak Type epoxy resin (epoxy resin with cresol novolak as precursor), phenol novolak type epoxy resin (epoxy resin with phenol novolak as precursor), resorcinol type epoxy resin (epoxy resin with resorcinol as precursor), naphthalene type epoxy Resin (epoxy resin having dihydroxynaphthalene as a precursor), biphenyl type epoxy resin (epoxy resin having dihydroxybiphenyl as a precursor), fluorene type epoxy resin (bishydroxy Phenylfluorene as a precursor and an epoxy resin), dicyclopentadiene type epoxy resin (an epoxy resin composed of a condensate of dicyclopentadiene and phenol), bisphenol A type epoxy resin (an epoxy resin having bisphenol A as a precursor), and bromination Examples include bisphenol A type resin, bisphenol F type epoxy resin (epoxy resin having bisphenol F as a precursor), and bisphenol S type epoxy resin (epoxy resin having bisphenol S as a precursor). When using these,
Used alone or in combination with a glycidylamine type epoxy resin.

Dicyandiamide (hereinafter referred to as DICY) used as the component [B] in the present invention is:
It is a particulate compound that hardly dissolves in epoxy resin at 25 ° C, but dissolves when heated to 100 ° C or higher, and is a curing agent that reacts with epoxy resin. That is,
It has the property of being insoluble at low temperatures and soluble at high temperatures. Since the curing agent has such a potential, the epoxy resin composition containing DICY exhibits excellent storage stability.

In preparing a prepreg, particles having a large particle diameter in the resin composition hardly enter into the reinforcing fiber bundle even when impregnated with pressure. For this reason, when the average particle diameter of DICY is large, the amount of the curing agent in the reinforcing fiber bundle decreases, and as a result, the curing may be uneven. These phenomena are
It is not preferable because the composite material is insufficient in compressive strength after water absorption. For these reasons, the average particle size of DICY is 10 μm.
m or less, more preferably 7 μm or less. When the average particle size is 10 μm or less, the matrix resin is uniformly cured, and a fiber-reinforced composite material having excellent compressive strength even after absorbing water can be obtained. Conversely, when the average particle diameter of DICY is small, the solubility in epoxy resin is improved,
As a result, the reaction may easily proceed. Such a phenomenon is not preferable because it causes insufficient storage stability of the prepreg at room temperature. For these reasons, the average particle size of DICY is preferably 0.1 μm or more, more preferably 1 μm or more.

The DI which is the component [B] in the present invention
CY is preferably used in an amount of 2 to 10 parts by weight based on 100 parts by weight of the epoxy resin as the component [A]. 2
If the amount is less than 10 parts by weight, the curing reaction is likely to be incomplete even when sufficiently heated. If the amount exceeds 10 parts by weight, those that do not directly contribute to the curing reaction remain in the cured product, which may adversely affect the physical properties of the cured product and the composite material.

When DICY is used alone as a curing agent, heating at 180 ° C. for about 2 hours is generally required for sufficient curing. However, if DICY is used in combination with a curing accelerator, curing can be performed at a lower temperature. As such curing accelerators, imidazole compounds and urea compounds are well known. However, when an imidazole compound is used as an accelerator, curing occurs at 100 ° C. for about 2 hours, but storage stability at 25 ° C. tends to be insufficient. When a urea compound is used as an accelerator, storage stability at 25 ° C. is sufficient,
Heating at 0 ° C. for about 2 hours does not cure sufficiently. That is,
It is usually difficult to simultaneously satisfy the two requirements that the curing reaction proceeds easily at 100 ° C. and the curing reaction hardly proceeds at 25 ° C.

However, the present inventors have found that a resin composition using an adduct of an imidazole compound and an epoxy compound as a curing accelerator for DICY can simultaneously satisfy these two requirements. Furthermore, it was surprisingly found that the cured product of the resin composition, the carbon fiber and the adhesiveness were excellent. Therefore, even after water absorption, the adhesion between the fiber and the resin is slightly deteriorated, and the rigidity of the cured matrix resin is sufficiently reflected in the compressive strength of the fiber-reinforced composite material.

In the present invention, the adduct of the imidazole compound and the epoxy compound used for the component [C] preferably has a melting point in the range of 90 to 130 ° C. If the temperature is lower than 90 ° C., the storage stability at 25 ° C. tends to be insufficient.
The curing reactivity at ℃ tends to be insufficient.

In the present invention, the adduct of the imidazole compound and the epoxy compound used in the component [C] is preferably added in an amount of 1 to 15 parts by weight based on 100 parts by weight of the epoxy resin as the component [A]. If the amount exceeds 15 parts by weight, the accelerating effect is too strong and the storage stability at room temperature tends to be insufficient, while if less than 1 part by weight, the accelerating effect is too weak and the curing reactivity during molding tends to be insufficient.

If necessary, an adduct of the imidazole compound and the epoxy compound may be further coated with a resin. If this resin film is selected so as to be destroyed by heating or pressurizing, the compatibility between storage stability at room temperature and curing reactivity at the time of molding becomes more firm.

For the same reason as described in the case of DICY, the adduct of the imidazole compound and the epoxy compound has an average particle size of preferably 10 μm or less, more preferably 0.1 to 10 μm, and still more preferably. Is 1
It is preferably in the form of particles having a size of about 7 μm.

In the present invention, the imidazole compound used for the component [C] is, specifically, 2-
Methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 1-
Benzyl-2-methylimidazole, 1-benzyl-2
-Ethylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-ethyl-4-methylimidazole, 1-benzyl-2-ethyl-4-methylimidazole, 1-benzyl-2-ethyl-5-methyl Imidazole, 1- (2-cyanoethyl) -2-methylimidazole, 1- (2-cyanoethyl) -2-ethylimidazole, 1- (2-cyanoethyl) -2-isopropylimidazole, 1- (2-cyanoethyl) -2 -Phenylimidazole, 1- (2-cyanoethyl) -2-
Examples thereof include ethyl-4-methylimidazole and 1- (2-cyanoethyl) -2-ethyl-5-methylimidazole.

Examples of the epoxy compound used for component [C] in the present invention include butyl glycidyl ether, phenyl glycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and bisphenol A diglycidyl ether. , Bisphenol F diglycidyl ether, glycerin triglycidyl ether and the like. The molecular weight of these epoxy compounds is 200
To 1000 is preferable. If it is less than 200, the adduct with the imidazole compound is easily dissolved in the epoxy resin, and storage stability tends to be insufficient. Conversely, if it exceeds 1,000, the curing reactivity tends to be insufficient because the adduct with the imidazole compound is hardly soluble in the epoxy resin.

In the present invention, the constituent elements [A], [B],
A thermoplastic resin, a thermoplastic elastomer, an elastomer, inorganic particles, and the like may be further added to the epoxy resin composition containing [C] as an essential component. These modifiers are added for the purpose of controlling the rheology of the uncured composition, improving the toughness of the cured resin, controlling the tack of the prepreg, and improving the adhesion between the carbon fiber and the cured resin.

Specific examples of the thermoplastic resin used in the present invention include polyacetal, polyamide, polyamideimide, polyarylene oxide, polyarylate, polyimide, polyethylene, polyethylene terephthalate, polyethylene naphthalate, polyetherimide, and polyether. Ether ketone, polyether ketone, polyether sulfone, polyvinyl chloride, polycarbonate, polyvinyl acetate, polystyrene, polysulfone, polytetrafluoroethylene, polyhydroxyether, polyvinyl acetal, polyvinyl alcohol,
Polyvinyl pyrrolidone, polyvinyl formal, polyphenylene oxide, polybutylene terephthalate, polyphenylene sulfide, polypropylene, polybenzimidazole, polymethyl methacrylate and the like can be mentioned. These thermoplastic resins may be used alone or in combination.

Among these thermoplastic resins, polyamides are particularly effective in improving the toughness without significantly impairing the heat resistance and water resistance of the cured product. As a result, the impact resistance of the composite material is improved. Also, especially polyether sulfone,
It is effective for improving the adhesion to carbon fibers without substantially impairing the rigidity of the cured product. As a result, the compressive strength of the composite material is improved. When these thermoplastic resins are blended into the epoxy resin composition, it is preferable to add 5 to 25 parts by weight based on 100 parts by weight of the epoxy resin as the component [A]. If the amount is less than 5 parts by weight, the modifying effect by the addition is not sufficient, and if it exceeds 25 parts by weight, the impregnating property of the reinforcing fiber in the prepreg with the resin composition may be insufficient.

As the thermoplastic elastomer, a block copolymer having a soft segment having a polyether structure and a hard segment having an aliphatic polyamide structure or an aromatic polyester structure is preferable. When these polyamide-based or polyester-based thermoplastic elastomers are added, the toughness of the cured product is improved, and the rigidity of the cured product is easily maintained as compared with the case where an ordinary elastomer is added.

When the melting point of the polyamide-based or polyester-based thermoplastic elastomer is lowered,
The rigidity of the cured product at high temperatures decreases. For this reason, the melting point of the thermoplastic elastomer is preferably 100 ° C. or higher, more preferably 140 ° C. or higher. Further, when comparing the case where a polyamide-based thermoplastic elastomer and a polyester-based thermoplastic elastomer are added, the former is more preferable because the compressive strength of the composite material is superior to the latter.

The elastomer may be a liquid one,
Although the solid may be used, it is generally preferable to add the same amount to the epoxy resin because the latter can maintain the rigidity of the cured product rather than the former. As the solid elastomer, an acrylonitrile-butadiene copolymer is preferable because of its excellent compatibility with the epoxy resin. By changing the copolymerization ratio of acrylonitrile and butadiene, the compatibility with the epoxy resin can be adjusted. Use of a copolymer having a functional group that reacts with an epoxy resin such as an amino group or a carboxyl group is particularly effective in improving the toughness of a cured product.

Further, as the elastomer, core / shell type elastomer particles having an elastomer particle as a core component and the surface of which is covered with a shell component other than the elastomer can be used. The composition of the core / shell type elastomer is preferably such that the core component is in the range of 10 to 90% by weight and the shell component is in the range of 90 to 10% by weight. When the content of the core component is less than 10% by weight, a large amount of particles are required to improve toughness, and as a result, the rigidity of the resin tends to be insufficient. If the shell component is less than 10% by weight, the core cannot be completely covered with the shell, and the viscosity of the resin may change with time. Examples of the core component include acrylonitrile-butadiene rubber, urethane rubber, and styrene-butadiene rubber. Examples of the shell component include polyacrylate, polyacrylonitrile, polystyrene, polymethyl methacrylate, and the like.

Specific examples of the inorganic particles include alumina, carbon black, kaolin clay, graphite, aluminum silicate, tin oxide, titanium oxide, antimony trioxide, molybdenum trioxide, silica, zirconia, aluminum hydroxide, and water. Magnesium oxide, smectite, sericite, talc, calcium carbonate, magnesium carbonate, ferrite, mica, montmorillonite,
Molybdenum sulfide and the like can be given. By adding these inorganic particles, the rigidity of the cured product can be improved. Among them, particulate silica is preferably used because it is particularly effective in improving the rigidity of the cured product after water absorption. The particulate silica is of a hydrophilic type in which silicon dioxide is a basic skeleton and the surface thereof is covered with a silanol group, and a hydrophobic type in which hydrogen of the silanol group is substituted with an alkyl group, a silyl group, or the like. There is. Hydrophobic silica is more effective than hydrophilic silica in improving rigidity after water absorption. If the average particle size of the silica particles is too large, the orientation of the carbon fibers may be disturbed. Conversely, if the average particle size is too small, the tack of the prepreg may be insufficient. It is preferably in the range of １1 μm.

In the present invention, carbon fibers are used as the reinforcing fibers. Aramid fiber, glass fiber,
Steel fibers, carbon fibers, nylon fibers, polyester fibers, and the like are well known, but among these, carbon fibers are particularly excellent in terms of strength, elastic modulus, specific gravity, and the like. The carbon fiber has a tensile strength of preferably 4
000 MPa or more, more preferably 4500 MPa or more is used. If the tensile strength is less than 4000 MPa, when used for structural materials such as aircraft, the tensile strength of the composite material may be insufficient.

The carbon fiber is composed of a single fiber, and the single fiber preferably has a substantially circular cross section.
Specifically, if the ratio (R / r) of the radius R of the circumscribed circle and the radius r of the inscribed circle of the cross-sectional shape of the single fiber is defined as the degree of deformation of the single fiber, the degree of deformation of the single fiber is 1. 1 or less.

In general, the adhesiveness between a carbon fiber having a substantially circular cross section and an epoxy resin tends to be low. As a result, even if the rigidity of the cured resin is high, the compressive strength of the composite material is often insufficient. But,
The epoxy resin composition of the present invention can sufficiently adhere to carbon fibers having a substantially circular cross section.
Therefore, even after absorbing water, the rigidity of the cured resin is sufficiently reflected in the compressive strength of the composite material.

The form and arrangement of the carbon fibers are not particularly limited. For example, long fibers aligned in one direction,
Fabrics, braids, tows, knits, mats and the like can be used. The content of carbon fiber in the prepreg is 50
It is preferably in the range of ~ 80% by weight. If the amount is less than 50% by weight, the amount of reinforcing fibers is insufficient, so that the compressive strength and tensile strength of the composite material tend to be insufficient. 80% by weight
When the ratio exceeds the above, fatigue occurs due to rubbing between the single fibers of the carbon fibers, and the compressive strength and tensile strength of the composite material are apt to be insufficient.

The prepreg of the present invention is obtained, for example, by heating and melting the uncured epoxy resin composition and then applying it to release paper using a film coater or the like to produce a resin film, which is prepared from one side or both sides of carbon fibers. By laminating resin films and applying heat and pressure, carbon fibers can be produced by impregnating the epoxy resin composition.

In this case, the impregnation temperature is preferably in the range of 60 to 110 ° C. If the temperature is lower than 60 ° C., impregnation of the carbon fiber with the epoxy resin composition becomes incomplete, and the tack of the prepreg tends to be excessive. Also, 110
When the temperature exceeds ℃, the impregnation of the epoxy resin composition into the carbon fibers becomes almost complete, but the curing reaction proceeds in the epoxy resin composition during the impregnation, and the drape of the prepreg tends to be impaired.

The prepreg of the present invention can be stored for a long period of 6 months to 1 year if refrigerated or frozen, and has excellent storage stability. Further, since the storage stability at room temperature is also excellent, even if the prepreg is left at room temperature for about one week, the tack or drape changes little with time and is easy to handle.

[0039] The prepreg of the present invention is laminated and usually heat-cured to obtain a fiber-reinforced composite material. In order to eliminate the anisotropy in the strength of the composite material, it is preferable that the prepregs made of the long fibers aligned in one direction are laminated while changing the fiber direction little by little to obtain a pseudo-isotropic material. The heating conditions in such a case are preferably in the range of 80 to 110 ° C. If the temperature is lower than 80 ° C., the curing becomes insufficient,
As a result, heat resistance and water resistance tend to be insufficient. Also, 11
If the temperature exceeds 0 ° C., curing is sufficient, but thermal shrinkage when the temperature is returned from the molding temperature to room temperature cannot be ignored, and when a large structure is produced, internal stress tends to accumulate.

[0040]

The present invention will be described more specifically with reference to the following examples.

In this example, the following materials were used.

<Epoxy resin> Tetraglycidylamine type epoxy resin (epoxy equivalent: 120) ELM-43
4 (Sumitomo Chemical Co., Ltd.) The chemical structural formula is as follows.

[0043]

Embedded image Phenol novolak epoxy resin Ep-154
(Manufactured by Yuka Shell Co., Ltd.) The chemical structural formula is as follows.

[0044]

Embedded image Cresol novolak epoxy resin ESCN220
(Sumitomo Chemical Co., Ltd.) The chemical structural formula is as follows.

[0045]

Embedded image Bisphenol A type epoxy resin YD-128 (manufactured by Toto Kasei Co., Ltd.) The chemical structural formula is as follows. In the following chemical formula, N is about 0.14.

[0046]

Embedded image Bisphenol A type epoxy resin Ep1001 (manufactured by Yuka Shell Co., Ltd.) The chemical structural formula is as follows. In the following chemical formula, N is about 1.97.

[0047]

Embedded image In these chemical structural formulas, G means a glycidyl group. The glycidyl group has the following chemical structure.

[0048]

Embedded image <Curing agent> DICY average particle diameter 7 μm DDS <Curing accelerator> Adduct of imidazole compound and epoxy compound (melting point 100 ° C., average particle diameter 10 μm) PN-2
3 (manufactured by Ajinomoto Co., Ltd.) Dichlorophenyldimethylurea (hereinafter referred to as DCMU) <Modifier> Polyamide fine particles SP-500 (manufactured by Toray Industries, Inc.) Polyethersulfone PES 5003P (manufactured by Mitsui Chemicals, Inc.) Silica fine particles R812 (manufactured by Nippon Aerosil Co., Ltd.)
Average particle size 7 nm <Carbon fiber> T700S (manufactured by Toray Industries, Inc.) Tensile strength 4900 MPa
Deformation degree in cross section 1.05 T800H (manufactured by Toray Industries, Inc.) Tensile strength 5500 MPa
Degree of cross-sectional deformation 1.37 (Examples 1 to 6, Comparative Examples 1 and 2) Epoxy resin compositions of compositions 1 to 8 were prepared by kneading necessary materials so as to have the compositions shown in Table 1 with a kneader. I got something. The prepregs of Examples 1 to 6 and Comparative Examples 1 and 2 were produced using a combination of the carbon fiber and the epoxy resin composition shown in Table 2. In preparing a prepreg, a resin film (basis weight: 52 g / m ² ) obtained by applying an epoxy resin composition on release paper using a film coater was previously unidirectionally aligned in a carbon fiber bundle. From both sides of the sheet (with a basis weight of 190 g / m ² ) by heating and pressing.

For each prepreg obtained,
(+ 45/0 / -45 / 90 degrees)_2S Product with 16 layers
Layer, in an autoclave, at the curing temperature and curing time shown in Table 2.
Cured between each, each fiber reinforced composite material cured plate
Obtained. Then, from this cured plate, the direction of 0 degree is 304.8.
Cut out a rectangular plate of 38.1 mm in 90-degree direction
After that, a circular hole with a diameter of 6.35 mm is made in the center.
Then, a perforated plate was produced. Put this perforated plate in hot water of 71 ° C for 2 hours.
After soaking for weeks, the compressive strength at 82 ° C was measured.
Was. The evaluation results of the compressive strength were as shown in Table 2.
The fiber-reinforced composite material obtained from the prepreg of the present invention
High compression strength and excellent heat and water resistance
You.

[0050]

[Table 1] In Table 1, the numerical values of each composition are parts by weight.

[0051]

[Table 2]

[0052]

The prepreg of the present invention is sufficiently cured by heating at 100 ° C. for about 2 hours and has no problem in handling such as life, tack and drape. Further, the fiber-reinforced composite material obtained by laminating the prepreg and heating and curing is excellent in heat resistance, water resistance and adhesion between the fiber and the resin. Therefore, even in a high temperature state after water absorption, it has a sufficient compressive strength as a structural material used for an aircraft or the like.

Claims (7)

[Claims] 1. A prepreg essentially comprising the following components [A], [B], [C] and [D]. [A] Epoxy resin containing glycidylamine type epoxy resin [B] Dicyandiamide [C] Adduct of imidazole compound and epoxy compound [D] Carbon fiber 2. The prepreg according to claim 1, wherein the glycidylamine type epoxy resin is tetraglycidyldiaminodiphenylmethane. 3. The dicyandiamide of component [B] is
The prepreg according to claim 1 or 2, wherein the prepreg is in the form of particles having an average particle diameter of 10 µm or less. 4. An adduct of an imidazole compound and an epoxy compound as the constituent element [C] has a melting point of 90 ° C. to 13 ° C.
4. The method according to claim 1, wherein the temperature is within a range of 0.degree.
The prepreg according to any one of the above. 5. The prepreg according to claim 1, wherein the carbon fiber of the constituent element [D] has a tensile strength of 4000 MPa or more. 6. A fiber-reinforced composite material obtained by laminating the prepreg according to any one of claims 1 to 5. 7. A fiber-reinforced composite material obtained by laminating the prepregs according to claim 1 and heating and curing at a temperature in the range of 80 ° C. to 110 ° C.