JP2016147926A - Epoxy resin composition for fiber-reinforced composite material, epoxy resin cured product, and fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition for a fiber-reinforced composite material, which has both high storage stability and high-speed curability and is capable of imparting high heat resistance and high strength to a fiber-reinforced composite material.SOLUTION: The epoxy resin composition for a fiber-reinforced composite material contains the following components (A) and (B): (A) a glycidyl amine type epoxy resin; and (B) a fluorene type curing agent. The component (A) is contained in an amount of 20 mass% or more based on the total mass of epoxy resin components in the epoxy resin composition.SELECTED DRAWING: None

Description

  The present invention relates to an epoxy resin composition for a fiber reinforced composite material suitably used for a fiber reinforced composite material such as an aircraft member, a spacecraft member, and an automobile member, and an epoxy resin cured product and a fiber reinforced composite material using the same. It is.

  Fiber reinforced composite materials composed of reinforced fibers and matrix resins can be designed using the advantages of reinforced fibers and matrix resins, so the applications are expanding to the aerospace field, sports field, general industrial field, etc. .

  As the reinforcing fiber, glass fiber, aramid fiber, carbon fiber, boron fiber or the like is used. As the matrix resin, either a thermosetting resin or a thermoplastic resin is used, but a thermosetting resin that can be easily impregnated into the reinforcing fiber is often used. As the thermosetting resin, epoxy resin, unsaturated polyester resin, vinyl ester resin, phenol resin, bismaleimide resin, cyanate resin and the like are used. Among these, an epoxy resin is preferably used from the viewpoints of adhesive properties between the resin and the reinforcing fibers, dimensional stability, and mechanical properties such as strength and rigidity of the obtained composite material.

As a forming method of the fiber reinforced composite material, a prepreg method, a hand lay-up method, a filament winding method, a pultrusion method, an RTM (Resin Transfer Molding) method, or the like is applied. In the prepreg method, a prepreg obtained by impregnating a reinforcing fiber with an epoxy resin composition is laminated in a desired shape and heated to obtain a molded product. However, if this epoxy resin composition or prepreg is stored at room temperature for a long period of time, there is a problem in storage stability because an unintended curing reaction proceeds. To date, as a means for ensuring the storage stability, a compound in which a latent curing agent such as dicyandiamide, a BF ₃ -amine complex, an amine salt, and a modified imidazole compound is blended in an epoxy resin is known. However, in these epoxy resin compositions, those having excellent storage stability tend to be inferior in curability, and those having excellent curability tend to be inferior in storage stability.

  Under such circumstances, a so-called microcapsule type curing in which a core containing an epoxy resin composition (Patent Document 1) in which a fluorene type curing agent is dispersed in a solid state and an amine curing agent is coated with a specific shell. An agent (Patent Document 2) has been proposed. However, the conventional techniques cannot achieve both storage stability and high-speed curability at a high level, and there is still room for improvement. In addition, an epoxy resin composition (Patent Document 3) using a combination of a fluorene type curing agent and a naphthalene type epoxy resin has been proposed, but it still cannot achieve both high storage stability and high-speed curability. Furthermore, since the viscosity of the epoxy resin composition is high, there is a limit to applications and molding methods, and the strength of the fiber reinforced composite material obtained from the epoxy resin composition is insufficient. Thus far, there are epoxy resin compositions that have both high storage stability and high-speed curability, and that can provide high heat-resistant and high-strength fiber-reinforced composite materials required for structural materials such as airplanes and automobiles. There wasn't.

Japanese National Patent Publication No. 11-511503 Japanese Patent Laid-Open No. 01-070523 International Publication No. 2014/049028

  The object of the present invention is to improve the drawbacks of the prior art, and have an epoxy resin composition for a fiber reinforced composite material that has both high storage stability and high-speed curability, and further provides a fiber reinforced composite material with high heat resistance and high strength. Is to provide.

In order to solve the above problems, the epoxy resin composition for fiber-reinforced composite material of the present invention has the following constitution. That is, an epoxy resin composition containing the following components (A) and (B), the fiber containing 20% by mass or more of the component (A) with respect to the total mass of the epoxy resin component in the epoxy resin composition It is an epoxy resin composition for reinforced composite materials.
(A) Glycidylamine type epoxy resin (B) Fluorene type curing agent

  In order to solve the above-mentioned problems, the cured epoxy resin of the present invention is obtained by curing the above-described epoxy resin composition for fiber-reinforced composite material, and the fiber-reinforced composite material of the present invention is the above-described fiber-reinforced composite material. It is formed by combining an epoxy resin composition for use with reinforcing fibers.

  According to the present invention, it is possible to provide an epoxy resin composition for a fiber reinforced composite material that has both high storage stability and high-speed curability, and further provides a high heat resistance and high strength fiber reinforced composite material. It becomes possible to provide a fiber-reinforced composite material.

The preferred embodiments of the present invention will be described below.
First, the epoxy resin composition for fiber-reinforced composite materials according to the present invention will be described.

  The epoxy resin means a compound containing one or more epoxy groups in the molecule.

The epoxy resin composition for fiber-reinforced composite materials according to the present invention is an epoxy resin composition containing the following components (A) and (B).
(A) Glycidylamine type epoxy resin (B) Fluorene type curing agent

  Component (A) in the present invention is a glycidylamine type epoxy resin. Specific examples thereof include N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, N, N-diglycidylaniline, N , N, N ′, N′-tetraglycidylxylylenediamine, and their derivatives, isomers, hydrogenated products such as alkyl, aryl, alkoxy, aryloxy, and halogen-substituted products. Of these, polyfunctional glycidylamine type epoxy resins are preferred. Such an epoxy resin has a high crosslinking density, and by using it, the heat resistance of the cured epoxy resin or the fiber-reinforced composite material can be improved. Among the above-described polyfunctional glycidylamine type epoxy resins, trifunctional or higher glycidylamine type epoxy resins, particularly trifunctional or higher functional glycidylamine type epoxy resins are preferable. Here, polyfunctional means that a plurality of glycidyl groups exist in one molecule, and trifunctional or more means that three or more glycidyl groups exist in one molecule.

  As the tri- or higher functional glycidylamine type epoxy resin, N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, or a derivative or isomer thereof is preferably used.

  For example, N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane, or derivatives or isomers thereof include N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane, N, N , N ′, N′-tetraglycidyl-3,3′-dimethyl-4,4′-diaminodiphenylmethane, N, N, N ′, N′-tetraglycidyl-3,3′-diethyl-4,4′- Diaminodiphenylmethane, N, N, N ′, N′-tetraglycidyl-3,3′-diisopropyl-4,4′-diaminodiphenylmethane, N, N, N ′, N′-tetraglycidyl-3,3′-di -T-butyl-4,4'-diaminodiphenylmethane, N, N, N ', N'-tetraglycidyl-3,3'-dimethyl-5,5'-diethyl-4,4'-diaminodi Phenylmethane, N, N, N ′, N′-tetraglycidyl-3,3′-diisopropyl-5,5′-diethyl-4,4′-diaminodiphenylmethane, N, N, N ′, N′-tetraglycidyl- 3,3′-diisopropyl-5,5′-dimethyl-4,4′-diaminodiphenylmethane, N, N, N ′, N′-tetraglycidyl-3,3′-di-t-butyl-5,5 ′ -Diethyl-4,4'-diaminodiphenylmethane, N, N, N ', N'-tetraglycidyl-3,3'-di-t-butyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, N, N, N ′, N′-tetraglycidyl-3,3 ′, 5,5′-tetramethyl-4,4′-diaminodiphenylmethane, N, N, N ′, N′-tetraglycidyl-3,3 ', 5,5'-Tet Ethyl-4,4′-diaminodiphenylmethane, N, N, N ′, N′-tetraglycidyl-3,3 ′, 5,5′-tetraisopropyl-4,4′-diaminodiphenylmethane, N, N, N ′ , N′-tetraglycidyl-3,3 ′, 5,5′-tetra-t-butyl-4,4′-diaminodiphenylmethane, N, N, N ′, N′-tetraglycidyl-3,3′-dichloro -4,4'-diaminodiphenylmethane, N, N, N ', N'-tetraglycidyl-3,3'-dibromo-4,4'-diaminodiphenylmethane, and the like.

  Further, for example, triglycidylaminophenol, or a derivative or isomer thereof includes N, N, O-triglycidyl-p-aminophenol, N, N, O-triglycidyl-m-aminophenol, or derivatives thereof. Or an isomer etc. can be mentioned.

  The glycidylamine type epoxy resin has an effect of enhancing storage stability and heat resistance, and the proportion thereof must be 20% by mass or more with respect to the total mass of the epoxy resin component in the epoxy resin composition (however, The preferred ratio is 30% by mass or more. By making the ratio of the glycidylamine type epoxy resin in the epoxy resin component within the above-described range, the strength of the cured epoxy resin and the fiber reinforced composite material is improved and the heat resistance is improved. Such an epoxy resin component is a component in which all the epoxy resins in the epoxy resin composition are combined.

  Moreover, in this invention, if epoxy resins other than a component (A) are 80 mass% or less with respect to the whole mass of an epoxy resin component, you may be contained in the epoxy resin composition.

  Epoxy resins other than component (A) include bisphenol type epoxy compounds, phenol novolac type epoxy resins, cresol novolac type epoxy resins, resorcinol type epoxy resins, phenol aralkyl type epoxy resins, naphthol aralkyl type epoxy resins, dicyclopentadiene type epoxy resins. Examples thereof include resins, epoxy resins having a biphenyl skeleton, isocyanate-modified epoxy resins, tetraphenylethane type epoxy resins, and triphenylmethane type epoxy resins. More specific examples of the epoxy resin other than the component (A) include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, tetrabromobisphenol A diglycidyl ether, bisphenol AD diglycidyl ether, 2,2 ′, 6,6. '-Tetramethyl-4,4'-biphenol diglycidyl ether, diglycidyl ether of 9,9-bis (4-hydroxyphenyl) fluorene, triglycidyl ether of tris (p-hydroxyphenyl) methane, tetrakis (p-hydroxy Phenyl) ethane tetraglycidyl ether, phenol novolac glycidyl ether, cresol novolac glycidyl ether, glycidyl ether of phenol and dicyclopentadiene condensate, biphenyl aralkyl tree Glycidyl ether, triglycidyl isocyanurate, 5-ethyl-1,3-diglycidyl-5-methylhydantoin, oxazolidone type epoxy resin obtained by addition of bisphenol A diglycidyl ether and tolylene isocyanate, phenol aralkyl type epoxy resin, etc. Can be mentioned. Among them, the bisphenol type epoxy resin is preferable because it is excellent in the balance between toughness and heat resistance of the obtained cured epoxy resin, and the liquid bisphenol type epoxy resin is particularly preferable because it is excellent in impregnation into reinforcing fibers.

  In the present invention, “liquid” means that the viscosity at 25 ° C. is 1000 Pa · s or less, and “solid” means that there is no fluidity at 25 ° C or very low fluidity. Specifically, it means that the viscosity at 25 ° C. is larger than 1000 Pa · s. Viscosity was measured in accordance with JIS Z8803 (1991) "cone-viscosity measurement method using a plate-type rotational viscometer" and an E-type viscometer equipped with a standard cone rotor (1 ° 34 '× R24) (for example, Tokimec Co., Ltd.) Measured using TVE-30H). Here, the bisphenol type epoxy resin is obtained by glycidylation of two phenolic hydroxyl groups of a bisphenol compound. As the bisphenol type, bisphenol A type, bisphenol F type, bisphenol AD type, bisphenol S type, or these Examples include halogens of bisphenol, alkyl-substituted products, and hydrogenated products. Moreover, as a bisphenol-type epoxy resin, not only a monomer but the high molecular weight body which has several repeating units can also be used conveniently.

  From the viewpoint of the balance of the storage stability of the epoxy resin composition, the toughness of the cured epoxy resin and the heat resistance, it is preferable to further include an epoxy resin other than the component (A) as the epoxy resin component, The total mass of the epoxy resin component is preferably 20% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 70% by mass or less, and the content of the glycidylamine type epoxy resin is the total mass of the epoxy resin component. Is 20% by mass or more and 80% by mass or less, preferably 30% by mass or more and 80% by mass or less.

  Component (B) in the present invention is a fluorene type curing agent, and is an amine type curing agent having at least one fluorene skeleton in the molecule. The fluorene type curing agent usually has a 9,9-bis (aminophenyl) fluorene skeleton, and is specifically represented by the following structural formula [1].

Here, R ¹ and R ² are a substituent selected from hydrogen, a linear or branched alkyl group having 1 to 6 carbon atoms. In addition, the phenyl group and fluorene group contained in the 9,9-bis (aminophenyl) fluorene skeleton may be substituted with one or more atoms or substituents, and these are usually hydrogen, halogen, alkyl groups. , Aryl group, alkoxy group, aryloxy group, nitro group, acetyl group, or trimethylsilyl group, particularly preferably hydrogen.

Specific examples of the fluorene type curing agent include 9,9-bis (4-aminophenyl) fluorene, 4-methyl-9,9-bis (4-aminophenyl) fluorene, 4-chloro-9,9-bis ( 4-aminophenyl) fluorene, 2-ethyl-9,9-bis (4-aminophenyl) fluorene, 2-iodo-9,9-bis (4-aminophenyl) fluorene, 3-bromo-9,9-bis (4-aminophenyl) fluorene, 9- (4-methylaminophenyl) -9- (4-ethylaminophenyl) fluorene, 1-chloro-9,9-bis (4-aminophenyl) fluorene, 2-methyl- 9,9-bis (4-aminophenyl) fluorene, 2-fluoro-9,9-bis (4-aminophenyl) fluorene, 1,2,3,4,5,6,7,8-octafluor Oro-9,9-bis (4-aminophenyl) fluorene, 2,7-dinitro-9,9-bis (4-aminophenyl) fluorene, 2-chloro-4-methyl-9,9-bis (4- Aminophenyl) fluorene, 2,7-dichloro-9,9-bis (4-aminophenyl) fluorene, 2-acetyl-9,9-bis (4-aminophenyl) fluorene, 2-methyl-9,9-bis (4-aminophenyl) fluorene, 2-chloro-9,9-bis (4-aminophenyl) fluorene, and 2-t-butyl-9,9-bis (4-aminophenyl) fluorene, 9,9-bis (4-methylaminophenyl) fluorene, 9- (4-methylaminophenyl) -9- (4-aminophenyl) fluorene, 9,9-bis (4-ethylaminophenyl) fluorene 9- (4-ethylaminophenyl) -9- (4-aminophenyl) fluorene, 9,9-bis (4-propylaminophenyl) fluorene, 9,9-bis (4-isopropylaminophenyl) fluorene, 9, 9-bis (4-butylaminophenyl) fluorene, 9,9-bis (3-methyl-4-methylaminophenyl) fluorene, 9,9-bis (3-chloro-4-methylaminophenyl) fluorene, 9- (4-methylaminophenyl) -9- (4-ethylaminophenyl) fluorene, 9,9-bis (3,5-dimethyl-4-methylaminophenyl) fluorene, 9- (3,5-dimethyl-4- Methylaminophenyl) -9- (4-methylaminophenyl) fluorene, 1,5-dimethyl-9,9-bis (3,5-dimethyl-4-methyl) Ruaminophenyl) fluorene, 4-methyl-9,9-bis (4-methylaminophenyl) fluorene, 4-chloro-9,9-bis (4-methylaminophenyl) fluorene, 9,9-bis (3 5-diethyl-4-methylaminophenyl) fluorene. Particularly preferred is a fluorene-type curing agent in which R ¹ and R ² are both hydrogen in the structural formula [1].

  Specific examples of such a particularly preferred fluorene type curing agent include 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (3-methyl-4-aminophenyl) fluorene, and 9,9-bis. (3-ethyl-4-aminophenyl) fluorene, 9,9-bis (3-phenyl-4-aminophenyl) fluorene, 9,9-bis (3,5-dimethyl-4-aminophenyl) fluorene, 9- (3,5-diethyl-4-aminophenyl) -9- (3-methyl-4-aminophenyl) fluorene, 9- (3-methyl-4-aminophenyl) -9- (3-chloro-4-amino Phenyl) fluorene, 9,9-bis (3,5-diisopropyl-4-aminophenyl) fluorene, 9,9-bis (3-chloro-4-aminophenyl) fluorene. .

  Component (B) mainly undergoes a curing reaction at 130 ° C. or higher, and exhibits latent thermal reactivity. Thereby, the epoxy resin composition using the same is excellent in handleability without causing an early reaction of the curing agent at less than 130 ° C.

  The epoxy resin composition of the present invention may contain a curing agent other than the component (B) for the purpose of adjusting physical properties such as curability and storage stability. Such a curing agent is an amine curing agent having an amino group having active hydrogen and forming a crosslinked structure with an epoxy resin, and is not particularly limited as long as it is other than the component (B). An aromatic amine curing agent that can provide a cured epoxy resin cured with high elasticity is preferred. Specific examples of the aromatic amine curing agent include 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, and 3,3′-diisopropyl-4,4. '-Diaminodiphenylmethane, 3,3'-di-t-butyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3' -Di-t-butyl-5,5'-dimethyl-4,4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetraethyl-4,4'-diaminodiphenylmethane, 3,3'-diisopropyl-5 , 5'-diethyl-4,4'-diaminodiphenylmethane, 3,3'-di-t-butyl-5,5'-diethyl-4,4'-diaminodiphenylmeta 3,3′-di-t-butyl-5,5′-diisopropyl-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetra-t-butyl-4,4′-diamino Solid aromatic amine curing agent such as diphenylmethane, 2,2′-diethyldiaminodiphenylmethane, 2,4-diethyl-6-methyl-m-phenylenediamine, 4,6-diethyl-2-methyl-m-phenylenediamine Such as diethyltoluenediamine, 4,4′-methylenebis (N-methylaniline), 4,4′-methylenebis (N-ethylaniline), 4,4′-methylenebis (N-sec-butylaniline), N, N Examples include liquid aromatic amine curing agents such as' -di-sec-butyl-p-phenylenediamine, or a mixture of solid and liquid aromatic amine curing agents.In particular, if the aromatic amine curing agent is in a liquid state, it is preferable because an epoxy resin cured product having excellent heat impregnation property and high heat resistance and high elastic modulus can be obtained.

  In the epoxy resin composition, the content of all curing agents including the component (B) is the ratio of the total active hydrogen number (H) of the curing agent to the total number of epoxy groups (E) in all epoxy resin components, It can be represented by so-called H / E, and the H / E is preferably a content satisfying a range of 0.8 to 1.1, and a content satisfying a range of 0.85 to 1.05 More preferably. When H / E is less than 0.8, the reaction rate of the cured epoxy resin is insufficient, and heat resistance and material strength may be reduced. When H / E exceeds 1.1, the reaction rate of the cured epoxy resin is sufficient, but the plastic deformation capability is insufficient, and the impact resistance of the fiber-reinforced composite material may be insufficient. The content of component (B) is the ratio of the number of active hydrogens derived from component (B) to the total number of active hydrogens (H) of the curing agent in the epoxy resin composition, the so-called active hydrogen ratio of component (B). It is preferable that the active hydrogen ratio of the component (B) is 20% or more. In this case, the storage stability of the epoxy resin composition that the component (B) has and the heat resistance of the cured epoxy resin are shown. The effect of increasing is fully exhibited.

  From the viewpoint of the mechanical properties of the fiber-reinforced composite material, it is also preferable to use a curing agent other than the component (B), for example, an aromatic amine type curing agent other than the component (B). In this case, the component (B) The active hydrogen ratio of the curing agent other than the component (B) is 20% or more and 80% or less.

  The epoxy resin composition of the present invention comprises a Lewis acid such as aluminum chloride, aluminum bromide, boron trifluoride, antimony pentafluoride, phosphorus pentafluoride, titanium tetrafluoride, etc. as a reaction accelerator, aliphatic or aromatic. Tertiary amines, imidazoles, alcohols, and phenols may be included.

  The fiber reinforced composite material using the epoxy resin composition for fiber reinforced composite material of the present invention can be suitably used for industrial material applications, particularly aircraft and automobile materials. Examples of the molding method of the fiber reinforced composite material include a prepreg method. In such a method, an unintended curing reaction hardly proceeds for a long time at a temperature lower than the molding temperature, and the molding temperature is cured in a short time. Therefore, it is necessary to use an epoxy resin composition having high storage stability and high-speed curability, and the epoxy resin composition for fiber-reinforced composite materials of the present invention is suitably used. The storage stability of the epoxy resin composition depends on the gelation time at a low temperature not higher than the molding temperature, for example, 120 ° C., and the longer the gelation time, the higher the storage stability. Further, the curability of the epoxy resin composition depends on the vitrification time at a molding temperature, for example, 180 ° C., and the curability is higher as the vitrification time is shorter. Therefore, the epoxy resin composition used in the prepreg method or the like is preferably an epoxy resin composition having a long gelation time at a low temperature below the molding temperature and a short vitrification time at the molding temperature, and the epoxy resin composition of the present invention. Satisfies such a requirement. Specifically, when the gelation time at 120 ° C. heating is X minutes and the vitrification time at 180 ° C. heating is Y minutes, the relationship of Y <0.72X + 9 is satisfied. More preferably, the relationship of Y <0.7X + 8 is satisfied.

Here, the gelation time and the vitrification time can be measured as follows. That is, the dynamic viscoelasticity measurement of the epoxy resin composition at a predetermined temperature is performed using a thermosetting measuring device such as ATD-1000 (manufactured by Alpha Technologies), and the complex viscosity is determined from the torque increase accompanying the progress of the curing reaction. Ask for. At this time, the time until the complex viscosity reaches 1.0 × 10 ³ Pa · s is the gelation time, and the time until the complex viscosity reaches 1.0 × 10 ⁷ Pa · s is the vitrification time.

  The heat resistance of the fiber reinforced composite material obtained by using the epoxy resin composition for fiber reinforced composite material of the present invention depends on the glass transition temperature of the cured epoxy resin obtained by curing the epoxy resin composition. In order to obtain a fiber-reinforced composite material having heat resistance, for example, the glass transition temperature of a cured epoxy resin obtained by heating for 2 hours at a temperature of 180 ° C. is 180 ° C. or higher and 250 ° C. or lower. It is preferable that it is 180 ° C. or higher and 220 ° C. or lower. When the glass transition temperature is less than 180 ° C., the heat resistance of the cured epoxy resin may be insufficient. When the glass transition temperature exceeds 250 ° C., the cross-linked density of the three-dimensional cross-linked structure becomes high, so that the cured epoxy resin becomes brittle, and the tensile strength and impact resistance of the fiber reinforced composite material may be lowered. Here, the glass transition temperature is determined by measurement using a dynamic viscoelasticity measuring device (DMA).

  The fiber reinforced composite material of the present invention is obtained by combining the epoxy resin composition for fiber reinforced composite material of the present invention and the reinforcing fiber and curing. The method for molding the fiber-reinforced composite material of the present invention is not particularly limited, but methods such as a prepreg method, a hand lay-up method, a filament winding method, a pultrusion method, and an RTM (Resin Transfer Molding) method are preferably used. It is done.

  Examples of the reinforcing fiber used in the present invention include glass fiber, carbon fiber, graphite fiber, aramid fiber, boron fiber, alumina fiber, and silicon carbide fiber. Two or more kinds of these reinforcing fibers may be mixed and used, but in order to obtain a molded product that is lighter and more durable, it is preferable to use carbon fibers or graphite fibers. In particular, in applications where there is a high demand for reducing the weight and strength of materials, carbon fibers are preferably used because of their excellent specific modulus and specific strength.

  As the carbon fiber, any type of carbon fiber can be used depending on the application, but a carbon fiber having a tensile elastic modulus of at most 400 GPa is preferable from the viewpoint of impact resistance. From the viewpoint of strength, a carbon fiber having a tensile strength of preferably 4.4 to 6.5 GPa is preferably used because a composite material having high rigidity and mechanical strength can be obtained. Further, the tensile elongation is also an important factor, and it is preferably a high-strength, high-stretch carbon fiber of 1.7 to 2.3%. Accordingly, carbon fibers having the characteristics that the tensile modulus is at least 230 GPa, the tensile strength is at least 4.4 GPa, and the tensile elongation is at least 1.7% are most suitable.

  Commercially available carbon fibers include "Torayca (registered trademark)" T800G-24K, "Torayca (registered trademark)" T800S-24K, "Torayca (registered trademark)" T700G-24K, and "Torayca (registered trademark)" T300- 3K, and “Torayca (registered trademark)” T700S-12K (manufactured by Toray Industries, Inc.).

  Hereinafter, the epoxy resin composition for fiber-reinforced composite material of the present invention will be described in more detail with reference to examples.

<Resin raw material>
In order to obtain the resin composition of each Example, the following resin raw materials were used. In addition, unless otherwise indicated, the unit of the content rate of the resin composition of Table 1 means a "mass part".

1. Component (A) epoxy resin “Araldite” (registered trademark) MY721 (manufactured by Huntsman Advanced Materials): Tetraglycidyldiaminodiphenylmethane “Araldite” (registered trademark) MY0600 (manufactured by Huntsman Advanced Materials) ): Triglycidyl-m-aminophenol

2. Epoxy resin other than component (A), “Epicron” (registered trademark) EPC830 (manufactured by Dainippon Ink Co., Ltd.): Bisphenol F type epoxy resin (viscosity: 3500 mPa · s (25 ° C.))
“Araldite” (registered trademark) MY816 (manufactured by Huntsman Advanced Materials): naphthalene type epoxy resin (viscosity: 300 mPa · s (150 ° C.))

3. Ingredient (B), curing agent, BAFL (manufactured by Tokyo Chemical Industry Co., Ltd.): 9,9-bis (4-aminophenyl) fluorene, BTFL (manufactured by Tokyo Chemical Industry Co., Ltd.): 9,9-bis ( 3-methyl-4-aminophenyl) fluorene / CAF (manufactured by Tokyo Chemical Industry Co., Ltd.): 9,9-bis (3-chloro-4-aminophenyl) fluorene

4). Curing agent other than component (B), 3,3′-DAS (manufactured by Mitsui Chemicals Fine Co., Ltd.): 3,3′-diaminodiphenyl sulfone (solid at 25 ° C. (viscosity> 1000 Pa · s))
"JER Cure" (registered trademark) W (manufactured by Mitsubishi Chemical Corporation): diethyltoluenediamine (viscosity: 160 mPa · s (25 ° C))

<Preparation of epoxy resin composition>
(A) An epoxy resin such as a glycidylamine type epoxy resin, (B) a curing agent such as a fluorene type curing agent, and a curing accelerator were mixed at a content ratio shown in Table 1 to prepare an epoxy resin composition.

<Measurement of gelation time>
The sample was put into a stage heated to 120 ° C. using a thermosetting measurement device ATD-1000 (manufactured by Alpha Technologies), and dynamic viscoelasticity measurement was performed at a frequency of 1.0 Hz and a strain of 1%, and the curing reaction proceeded. The complex viscosity was obtained from the torque increase accompanying the. At this time, the time until the complex viscosity reached 1.0 × 10 ³ Pa · s was defined as the gel time.

<Measurement of vitrification time>
A sample was put into a stage heated to 180 ° C. using a thermosetting measurement device ATD-1000 (manufactured by Alpha Technologies), and a dynamic viscoelasticity measurement was performed at a frequency of 1.0 Hz and a strain of 1%, and a curing reaction proceeded. The complex viscosity was obtained from the torque increase accompanying the. At this time, the time until the complex viscosity reached 1.0 × 10 ⁷ Pa · s was defined as the gel time.

<Preparation of cured resin plate>
The epoxy resin composition prepared above was degassed in vacuum, and then poured into a mold set to a thickness of 2 mm with a 2 mm thick “Teflon (registered trademark)” spacer. Curing was performed at a temperature of 180 ° C. for 2 hours to obtain a cured resin plate having a thickness of 2 mm.

<Measurement of glass transition temperature Tg of cured epoxy resin>
A test piece having a width of 12.7 mm and a length of 40 mm was cut out from the cured resin plate, and Tg measurement was performed using DMA (ARES manufactured by TA Instruments). The measurement conditions are a heating rate of 5 ° C./min. The temperature at the inflection point of the storage elastic modulus G ′ obtained by the measurement was defined as Tg.

<Production of fiber-reinforced composite material>
Carbon fiber unidirectional woven fabric (plain weave, warp: carbon fiber T800S-24K-10C, manufactured by Toray Industries, Inc., carbon fiber basis weight) cut into a mold having a plate-like cavity of 400 mm × 400 mm × 1.2 mm, 395 mm × 395 mm 295 g / m ² , warp density 7.2 / 25 mm, weft: glass fiber ECE225 1/0 1Z Nittobo Co., Ltd., weft density 7.5 / 25 mm), carbon fiber direction 0 °, 0 A set of four laminated in the direction was set and clamped. Subsequently, after the mold was heated to 80 ° C., an epoxy resin composition separately heated to 80 ° C. was injected into the mold at an injection pressure of 0.2 MPa using a resin injection device. After the injection, the mold was heated to 180 ° C. at a rate of 5 ° C./min, cured at 180 ° C. for 2 hours, then cooled to 30 ° C. and demolded to obtain a fiber-reinforced composite material.

<Method of measuring 0 ° tensile strength of fiber reinforced composite material>
The obtained fiber reinforced composite material was cut into a length of 229 mm and a width of 12.7 mm so that the length direction was the same as the 0 ° direction to obtain a 0 ° tensile strength test piece. The strength was measured using a universal material testing machine (Instron Japan Co., Ltd. Model 4208 Instron (registered trademark)) in accordance with ASTM-D3039. The crosshead speed during measurement was 1.27 mm / min, and the measurement temperature was 23 ° C.

Example 1
As described above, the epoxy resin composition was prepared at the content ratio described in Table 1, and the gelation time and the vitrification time were measured. As a result, the gelation time was 25 minutes and the vitrification time was 17 minutes. Satisfying the relationship of Y <0.72X + 9 and Y <0.7X + 8 when the gelation time at 120 ° C. heating is X minutes and the vitrification time at 180 ° C. heating is Y minutes. And high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg and 0 ° tensile strength were measured. As a result, Tg was 190 ° C., 0 ° tensile strength was 2950 MPa, and heat resistance and tensile strength were obtained. Both obtained good fiber reinforced composite materials.

(Example 2)
The result of producing an epoxy resin composition with the content ratio described in Table 1 in the same manner as in Example 1 except that the epoxy resin component was changed to MY0600 / EPC830 = 30/70, and measuring the gelation time and vitrification time. Y <0.72X + 9 when the gelation time is 30 minutes, the vitrification time is 22 minutes, the gelation time when heated at 120 ° C. is X minutes, and the vitrification time when heated at 180 ° C. is Y minutes, and The relationship of Y <0.7X + 8 was satisfied, and both storage stability and high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg, 0 ° tensile strength measurement was performed. As a result, Tg was 189 ° C., 0 ° tensile strength was 3050 MPa, heat resistance, tensile strength. Both obtained good fiber reinforced composite materials.

(Example 3)
Except having changed the content ratio of MY0600 and EPC830 to MY0600 / EPC830 = 50/50, an epoxy resin composition was prepared with the content ratio described in Table 1 in the same manner as in Example 2, and the gelation time and vitrification time measurement were performed. As a result, the gelation time is 20 minutes, the vitrification time is 16 minutes, the gelation time at 120 ° C. heating is X minutes, and the vitrification time at 180 ° C. heating is Y minutes. The relationship of 72X + 9 and Y <0.7X + 8 was satisfied, and both storage stability and high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg and 0 ° tensile strength were measured. As a result, Tg was 195 ° C., 0 ° tensile strength was 3000 MPa, and heat resistance and tensile strength were obtained. Both obtained good fiber reinforced composite materials.

Example 4
Except for changing the content ratio of MY0600 and EPC830 to MY0600 / EPC830 = 100/0 and H / E = 0.85, an epoxy resin composition was prepared with the content ratio described in Table 1 in the same manner as in Example 2. As a result of measuring the gelation time and the vitrification time, the gelation time was 10 minutes, the vitrification time was 12 minutes, the gelation time when heated at 120 ° C was X minutes, and the vitrification time when heated at 180 ° C was Y %, The relationship of Y <0.72X + 9 and Y <0.7X + 8 was satisfied, and both storage stability and high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg and 0 ° tensile strength measurement were performed. As a result, Tg was 202 ° C. and 0 ° tensile strength was 2900 MPa, and heat resistance and tensile strength were obtained. Both obtained good fiber reinforced composite materials.

(Example 5)
As a result of producing an epoxy resin composition with the content ratio described in Table 1 in the same manner as in Example 2 except that the component (B) BAFL was changed to BTFL, the gelation time and the vitrification time were measured. When the vitrification time is 22 minutes, the vitrification time is 16 minutes, the gelation time when heated at 120 ° C. is X minutes, and the vitrification time when heated at 180 ° C. is Y minutes, Y <0.72X + 9 and Y < The relationship of 0.7X + 8 was satisfied, and both storage stability and high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg and 0 ° tensile strength were measured. As a result, Tg was 190 ° C., 0 ° tensile strength was 3050 MPa, and heat resistance and tensile strength were obtained. Both obtained good fiber reinforced composite materials.

(Example 6)
An epoxy resin composition was prepared at the content ratio described in Table 1 in the same manner as in Example 2 except that the component (B), BAFL, was changed to CAF and H / E = 1.05, and the gelation time, glass As a result of measuring the vitrification time, when the gelation time is 300 minutes, the vitrification time is 200 minutes, the gelation time at 120 ° C. heating is X minutes, and the vitrification time at 180 ° C. heating is Y minutes The relationship of Y <0.72X + 9 and Y <0.7X + 8 was satisfied, and both storage stability and high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg and 0 ° tensile strength were measured. As a result, Tg was 180 ° C., 0 ° tensile strength was 3050 MPa, and heat resistance and tensile strength were obtained. Both obtained good fiber reinforced composite materials.

(Example 7)
An epoxy resin composition was prepared at the content ratio described in Table 1 in the same manner as in Example 2 except that BAFL as component (B) and 3,3′-DAS were used as other curing agents, and the gelation time, As a result of measuring the vitrification time, when the gelation time is 45 minutes, the vitrification time is 40 minutes, the gelation time when heated at 120 ° C. is X minutes, and the vitrification time when heated at 180 ° C. is Y minutes Although Y> 0.7X + 8, the relationship of Y <0.72X + 9 was satisfied, and both storage stability and high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg, 0 ° tensile strength measurement was performed. As a result, Tg was 184 ° C., 0 ° tensile strength was 3150 MPa, and heat resistance, tensile strength. Both obtained good fiber reinforced composite materials.

(Example 8)
The result which produced the epoxy resin composition by the content ratio described in Table 1 similarly to Example 7 except having changed the content ratio of BAFL and 3,3'-DAS, and measured gelation time and vitrification time. Y <0.72X + 9 when the gelation time is 36 minutes, the vitrification time is 29 minutes, the gelation time when heated at 120 ° C. is X minutes, and the vitrification time when heated at 180 ° C. is Y minutes, and The relationship of Y <0.7X + 8 was satisfied, and both storage stability and high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg, 0 ° tensile strength measurement was performed. As a result, Tg was 185 ° C., 0 ° tensile strength was 3120 MPa, and heat resistance, tensile strength. Both obtained good fiber reinforced composite materials.

Example 9
The result which produced the epoxy resin composition by the content ratio described in Table 1 similarly to Example 7 except having changed the content ratio of BAFL and 3,3'-DAS, and measured gelation time and vitrification time. Y <0.72X + 9 when the gelation time is 31 minutes, the vitrification time is 24 minutes, the gelation time when heated at 120 ° C. is X minutes, and the vitrification time when heated at 180 ° C. is Y minutes, and The relationship of Y <0.7X + 8 was satisfied, and both storage stability and high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg, 0 ° tensile strength measurement was performed. As a result, Tg was 187 ° C., 0 ° tensile strength was 3060 MPa, and heat resistance, tensile strength. Both obtained good fiber reinforced composite materials.

(Example 10)
Except for using BAFL as component (B) and jER Cure W as the other curing agent, an epoxy resin composition was prepared at the content ratio described in Table 1 in the same manner as in Example 2, and the gelation time and vitrification time were obtained. As a result of the measurement, the gelation time was 4 minutes, the vitrification time was 9 minutes, the gelation time at 120 ° C. heating was X minutes, and the vitrification time at 180 ° C. heating was Y minutes, Y < The relationship of 0.72X + 9 and Y <0.7X + 8 was satisfied, and both storage stability and high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg and 0 ° tensile strength measurement were performed. As a result, Tg was 186 ° C., 0 ° tensile strength was 3170 MPa, and heat resistance and tensile strength were obtained. Both obtained good fiber reinforced composite materials.

(Example 11)
Except having changed the content ratio of BAFL and jER cure W, the epoxy resin composition was produced by the content ratio described in Table 1 similarly to Example 10, and the gelation time and the vitrification time were measured. When time is 14 minutes, vitrification time is 14 minutes, gelation time when heated at 120 ° C. is X minutes, and vitrification time when heated at 180 ° C. is Y minutes, Y <0.72X + 9 and Y <0 The relationship of .7X + 8 was satisfied, and both storage stability and high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg and 0 ° tensile strength were measured. As a result, Tg was 187 ° C., 0 ° tensile strength was 3150 MPa, and heat resistance and tensile strength were obtained. Both obtained good fiber reinforced composite materials.

(Example 12)
Except having changed the content ratio of BAFL and jER cure W, the epoxy resin composition was produced by the content ratio described in Table 1 similarly to Example 10, and the gelation time and the vitrification time were measured. When time is 22 minutes, vitrification time is 18 minutes, gelation time when heated at 120 ° C. is X minutes, and vitrification time when heated at 180 ° C. is Y minutes, Y <0.72X + 9 and Y <0 The relationship of .7X + 8 was satisfied, and both storage stability and high-speed curability were good. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg and 0 ° tensile strength were measured. As a result, Tg was 188 ° C. and 0 ° tensile strength was 3110 MPa, and heat resistance and tensile strength were obtained. Both obtained good fiber reinforced composite materials.

(Comparative Example 1)
An epoxy resin composition was prepared in the same manner as in Example 2 except that the content ratio of MY0600 and EPC830 was changed to MY0600 / EPC830 = 0/100 and BAFL as the component (B) was changed to CAF. As a result of measuring the gelation time and the vitrification time, the gelation time was 350 minutes, the vitrification time was 360 minutes, the gelation time when heated at 120 ° C. was X minutes, and the vitrification time when heated at 180 ° C. When Y is Y, Y> 0.72X + 9, and storage stability and high-speed curability were not satisfied. In addition, as described above, a cured resin plate and a fiber-reinforced composite material were prepared, and Tg and 0 ° tensile strength were measured. As a result, Tg was 162 ° C. and 0 ° tensile strength was 2700 MPa, and heat resistance and tensile strength were obtained. Both results were not satisfactory.

(Comparative Example 2)
Except having changed the content ratio of MY721 and EPC830 to MY721 / EPC830 = 10/90, the epoxy resin composition was produced by the content ratio described in Table 1 like Example 1, and gelation time and vitrification time measurement were carried out. As a result, the gelation time was 36 minutes, the vitrification time was 39 minutes, the gelation time at 120 ° C. heating was X minutes, and the vitrification time at 180 ° C. heating was Y minutes, Y> 0. It was 72X + 9, and the results satisfying both the storage stability and the high-speed curability were not obtained. Further, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg and 0 ° tensile strength measurement were performed. As a result, Tg was 184 ° C., 0 ° tensile strength was 2750 MPa, and heat resistance was good. However, satisfactory results were not obtained for the tensile strength.

(Comparative Example 3)
An epoxy resin composition was prepared at the content ratio described in Table 1 in the same manner as in Example 2 except that the component (B) was changed to 3,3′-DAS instead of the fluorene-type curing agent, and the gelation time, As a result of measuring the vitrification time, the gelation time is 55 minutes, the vitrification time is 60 minutes, the gelation time at 120 ° C. heating is X minutes, and the vitrification time at 180 ° C. heating is Y minutes And Y> 0.72X + 9, and satisfactory results were not obtained in both storage stability and high-speed curability. Further, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg, 0 ° tensile strength measurement was performed. As a result, Tg was 183 ° C., 0 ° tensile strength was 2800 MPa, and heat resistance was good. However, satisfactory results were not obtained for the tensile strength.

(Comparative Example 4)
Except having changed into jER cure W instead of the fluorene type hardening | curing agent which is a component (B), an epoxy resin composition is produced by the content ratio described in Table 1 similarly to Example 2, and gelatinization time and vitrification time are produced. As a result of the measurement, when the gelation time is 0.5 minutes, the vitrification time is 12 minutes, the gelation time at 120 ° C. heating is X minutes, and the vitrification time at 180 ° C. heating is Y minutes. Y> 0.72X + 9, and satisfactory results for both storage stability and high-speed curability were not obtained. In addition, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg and 0 ° tensile strength measurement were performed. As a result, Tg was 185 ° C., 0 ° tensile strength was 2850 MPa, and heat resistance was good. However, satisfactory results were not obtained for the tensile strength.

(Comparative Example 5)
An epoxy resin composition was prepared at the content ratio described in Table 1 in the same manner as in Example 7 except that the content ratio of EPC830 and MY816 was changed to EPC830 / MY816 = 70/30 and H / E = 1.3, As a result of measuring the gelation time and the vitrification time, the gelation time is 330 minutes, the vitrification time is 330 minutes, the gelation time when heated at 120 ° C. is X minutes, and the vitrification time when heated at 180 ° C. is Y As a result, Y> 0.72X + 9, and satisfactory results for both storage stability and high-speed curability were not obtained. Moreover, as described above, a cured resin plate and a fiber reinforced composite material were prepared, and Tg and 0 ° tensile strength were measured. As a result, Tg was 170 ° C. and 0 ° tensile strength was 2650 MPa, and heat resistance and tensile strength were obtained. Both results were not satisfactory.

  As described above, the epoxy resin composition for fiber-reinforced composite materials of the present invention is excellent in storage stability and high-speed curability, and a high-performance fiber-reinforced composite material can be obtained in a short time with high productivity by a prepreg method or the like. . Moreover, the epoxy resin composition for fiber-reinforced composite materials of the present invention is excellent in molding large-sized fiber-reinforced composite materials, and is particularly suitable for application to aircraft and automobile members.

Since the epoxy resin composition for fiber-reinforced composite material of the present invention is excellent in storage stability and high-speed curability, it becomes possible to provide a highly heat-resistant and high-strength fiber-reinforced composite material with high productivity by a prepreg method or the like. As a result, the application of fiber reinforced composite materials for aircraft and automobile applications will progress, and further contributions to improving fuel economy and reducing greenhouse gas emissions due to further weight reduction can be expected.

Claims (11)

An epoxy resin composition comprising the following components (A) and (B), the fiber reinforced composite comprising 20% by mass or more of component (A) with respect to the total mass of the epoxy resin component in the epoxy resin composition: Epoxy resin composition for materials.
(A) Glycidylamine type epoxy resin (B) Fluorene type curing agent   The epoxy resin composition for fiber-reinforced composite materials according to claim 1, wherein the component (B) is a fluorene type curing agent having a 9,9-bis (aminophenyl) fluorene skeleton.   As a curing agent in the epoxy resin composition, an aromatic amine curing agent other than the component (B) is further included, and the ratio of the active hydrogen number derived from the component (B) to the total active hydrogen number of the curing agent in the epoxy resin composition The epoxy resin composition for fiber-reinforced composite materials according to claim 1 or 2, wherein is 20% or more and 80% or less.   The epoxy resin composition for fiber-reinforced composite materials according to claim 3, wherein the aromatic amine curing agent is liquid.   The epoxy resin composition for fiber-reinforced composite materials according to any one of claims 1 to 4, wherein the component (A) is a tri- or higher functional glycidylamine type epoxy resin.   6. The tri- or higher functional glycidylamine type epoxy resin is at least one selected from N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, or derivatives or isomers thereof. The epoxy resin composition for fiber-reinforced composite materials described in 1.   Triglycidylaminophenol, or a derivative or isomer thereof, is N, N, O-triglycidyl-p-aminophenol, N, N, O-triglycidyl-m-aminophenol, or a derivative or isomer thereof. The epoxy resin composition for fiber-reinforced composite materials according to claim 6.   The epoxy resin component further includes a bisphenol type epoxy resin, and the component (A) is included in an amount of 20% by mass to 80% by mass with respect to the total mass of the epoxy resin component in the epoxy resin composition. The epoxy resin composition for fiber-reinforced composite materials according to any one of the above.   The epoxy resin hardened | cured material formed by hardening | curing the epoxy resin composition for fiber reinforced composite materials in any one of Claims 1-8.   A fiber-reinforced composite material obtained by combining the epoxy resin composition for fiber-reinforced composite material according to any one of claims 1 to 8 and a reinforcing fiber and curing the combination. The fiber-reinforced composite material according to claim 10, wherein the reinforcing fibers are carbon fibers.