JPH11302507A - Epoxy resin composition for fiber-reinforced composite material, intermediate substrate for fiber-reinforced composite material and fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having both of a high degree of hardening reaction and stability in the preservation even under a hardening condition of 135 deg.C and about 2 hr, and capable of providing a hardened product having a high modulus even after dipping in boiling water for a long time by including a specific epoxy resin, a specified acid anhydride and particles of a specific amine-based compound. SOLUTION: The objective epoxy resin composition comprises (A) an epoxy resin selected from an alicyclic epoxy resin (e.g. limonene diepoxide), the epoxy resin having an aromatic ring and not containing nitrogen atom and a glycidyl ether of an aliphatic polyhydric alcohol, (B) acid anhydrides comprising (i) the acid anhydride liquid at a room temperature (e.g. methyltetrahydrophthalic anhydride) and (ii) an acid anhydride having two or more acid anhydride groups in one molecule (e.g. pyromellitic anhydride), and (C) particles consisting of an amine-based compound (e.g. 1-benzyl-2-methylimidazole) having 1-12 μm average particle diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite material used for structural materials such as aircraft, vehicles, ships and buildings, sports equipment, etc., namely, an epoxy resin composition for a fiber-reinforced composite material, and a fiber-reinforced composite material. And a fiber-reinforced composite material.

[0002]

2. Description of the Related Art Epoxy resins are mainly used as matrix resins for composite materials used in aircraft and the like because of their excellent properties such as mechanical properties and thermal properties. As a curing agent for an epoxy resin for this purpose, diaminodiphenyl sulfone is widely used because of its high rigidity and high glass transition temperature. When diaminodiphenyl sulfone is used as a curing agent, it is necessary to heat the matrix to about 180 ° C. to cure the matrix.

In order to promote energy saving during molding and reduce molding costs, there is a strong demand for the emergence of a matrix resin for a composite material which can be cured at a lower temperature of 135 ° C. However, in order to lower the curing temperature of the epoxy resin, the following two points are issues and it has been difficult to achieve them.

[0004] The first point is the heat resistance of the cured product. The heat resistance of the cured epoxy resin depends on the curing temperature and is cured at a temperature lower than 180 ° C., and it is difficult to obtain the same heat resistance as the epoxy resin cured at 180 ° C. The heat resistance required here means not only that the mechanical properties do not decrease to high temperatures, but also that the mechanical properties do not decrease to high temperatures even during water absorption.

[0005] The second point is the storage stability of the resin composition in an uncured state. Being able to cure at low temperatures means that the curing reaction is possible at lower temperatures, which means that it is more reactive than conventional compositions. Therefore, there arises a problem that the curing reaction proceeds gradually during storage and the usable time is shortened. Since the purpose of the low-temperature curing is to reduce the molding cost as described above, the storage stability needs to be at the same level as the conventional one.

[0006] Acid anhydride curing agents have hitherto been used for electric insulating materials and in filament winding methods.
In the former, the electrical properties are particularly good, and in the latter, the low viscosity of the compound with the epoxy resin is the main reason used. The curing reactivity of the acid anhydride curing agent is slower than that of the amine curing agent. Therefore, when the curing accelerator is not used, the curing reaction has a higher temperature and longer time than the amine curing agent, and the curing accelerator is used. In some cases, it may be possible to cure at lower temperatures than amine curing agents, but it has never been used as a matrix resin curing agent in aircraft applications, as the storage stability of the formulation is greatly sacrificed.

As an example using an acid anhydride curing agent, see
In JP-A-7-84844, it is used as a resin for a copper-clad laminate, in JP-A-62-199770, as a resin for die bonding, and in JP-A-61-255926, as a resin for potting and sealing agents for electric parts. As a resin,
JP-A-3-185022 discloses that the use of a specific acid anhydride as a heat-resistant resin is advantageous for heat resistance. However, each of them requires curing at a high temperature of 150 ° C. to 230 ° C. in order to obtain the required properties, and does not disclose curing at 135 ° C. Further, there is no suggestion for use as a matrix resin in aircraft applications or the like that require high compressive strength in a water-absorbing and high-temperature state.

Japanese Patent Application Laid-Open No. 7-268067 discloses that as an FRP resin, an acid anhydride curing agent and a curing accelerator are used in combination, that the storage stability is good and that curing at 120 ° C. is possible. Have been. This is a resin for molding methods such as filament winding and resin transfer molding methods, and these molding methods only require storage stability in the order of several hours from compounding the resin to using it. This level of storage stability cannot be applied to resins for aircraft composites, which require storage stability in units of several days.

[0009]

SUMMARY OF THE INVENTION
An epoxy resin that achieves both a high curing reaction rate and stability during storage under curing conditions with heating for about 2 hours, and has a high rigidity even after immersion in boiling water at 100 ° C. for 20 hours. An object of the present invention is to provide a composition, an intermediate substrate for a fiber-reinforced composite material capable of providing a fiber-reinforced composite material having excellent strength in a high temperature state of water absorption, and a fiber-reinforced composite material comprising the same.

[0010]

The present invention employs the following means in order to solve the above problems. That is, the epoxy resin composition for a fiber-reinforced composite material of the present invention is characterized by containing the following components. [A]: an epoxy resin comprising at least one selected from an alicyclic epoxy resin, an epoxy resin having an aromatic ring and containing no nitrogen atom, and a glycidyl ether of an aliphatic polyhydric alcohol [B]: (a) Acid anhydride which is liquid at room temperature and (b) an acid anhydride comprising an acid anhydride having two or more acid anhydride groups in one molecule [C]: from an amine compound having an average particle diameter of 1 μm or more and 12 μm or less In addition, the intermediate substrate for a fiber-reinforced composite material of the present invention is characterized in that such a resin composition is impregnated with reinforcing fibers.

Further, the fiber-reinforced composite material of the present invention is characterized in that it is obtained by curing such an intermediate base material for a fiber-reinforced composite material.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention has been made to solve the above-mentioned problems, namely,
Depending on the curing conditions of heating at 135 ° C for about 2 hours,
High compatibility with high curing reaction rate and storage stability
Even after being immersed in boiling water at 0 ° C. for 20 hours, the cured product provides an epoxy resin composition having a high rigidity. The subject of providing a fiber-reinforced composite material having excellent strength has been studied diligently, and it is composed of a combination of a specific epoxy resin, a specific acid anhydride, and a particle of a specific amine compound. When a resin composition is employed, it has been found that such a problem can be solved at once.
The component [A] of the present invention is an epoxy resin comprising at least one selected from an alicyclic epoxy resin, an epoxy resin having an aromatic ring and containing no nitrogen atom, and a glycidyl ether of an aliphatic polyhydric alcohol. is there.

Here, the alicyclic epoxy resin is an epoxy resin obtained by peroxidizing an alicyclic compound such as cyclohexene, cyclopentadiene or dicyclopentadiene. This epoxy resin is preferably used because of its high heat resistance and low water absorption of the cured product. Specifically, use may be made of vinylcyclohexene dioxide, dicyclopentadiene oxide, limonene dioxide, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate and its 6,6′-dimethyl derivative. Can be.

The epoxy resin having an aromatic ring is
It is preferably used because it has excellent elastic modulus and heat resistance of the cured product. However, those having a nitrogen atom in the molecule, such as glycidylamine type epoxy, promote the reaction between the acid anhydride curing agent and the epoxy resin and have poor stability during storage. From these viewpoints, the epoxy resin having an aromatic ring and containing no nitrogen atom suitable for the present invention includes, specifically, bisphenol A type epoxy resin, bisphenol AD type epoxy resin, bisphenol F type epoxy resin, bisphenol Bisphenol type epoxy resin such as S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, resorcinol type epoxy resin, biphenyl type epoxy resin, epoxy resin having naphthalene ring in the molecule, dicyclopentadiene skeleton Epoxy resin,
An epoxy resin having a fluorene skeleton in the molecule, an epoxy resin represented by the following general formula (1), and the like can be used.

[0015]

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Among them, examples of the diglycidyl ether type epoxy resin include bisphenol type epoxy resin, resorcinol type epoxy resin, biphenyl type epoxy resin, naphthalenediglycidyl ether, full orange glycidyl ether and the like.

Further, the glycidyl ether of an aliphatic polyhydric alcohol has a low viscosity and is preferably used for adjusting the viscosity of a blend. Specifically, ethylene glycol, diethylene glycol, and higher poly (oxyethylene) glycol, propane-1,2-diol and poly (oxypropylene) glycol, propane-1,3
-Diol, butane-1,4-diol, poly (oxytetramethylene) glycol, pentane-1,5-diol, hexane-1,6-diol, glycerol,
For example, 1,1,1, -trimethylolpropane, pentaerythritol, sorbitol, bis (4-hydroxycyclohexyl) methane, 2,2-bis (4-hydroxycyclohexyl) propane, 1,4-bishydroxymethylcyclohexane and the like are used. be able to.

The component [A] containing 50% by weight or more of the diglycidyl ether type epoxy resin is preferable because a sufficient curing reaction rate can be obtained. In addition,
Diglycidyl ether type epoxy resin, if the average epoxy equivalent is 300 or more, the curing reaction rate is insufficient, even if the curing reaction rate in the normal state is sufficient,
The epoxy equivalent of the diglycidyl ether type epoxy resin is preferably less than 300, since heat resistance in a water absorbing state becomes insufficient.

The component [B] of the present invention comprises two kinds of acids: (a) an acid anhydride which is liquid at room temperature, and (b) an acid anhydride having two or more acid anhydride groups in one molecule. It consists of an anhydride. (A) Examples of the acid anhydride which is liquid at room temperature include methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhymic anhydride, and trialkylmethyltetrahydrophthalic anhydride, but are not limited thereto. It is not something to be done.

(B) Examples of the acid anhydride having two or more acid anhydride groups in one molecule include pyromellitic anhydride, benzophenonetetracarboxylic anhydride, biphenyltetracarboxylic anhydride, and ethylene glycol bistrimellitic anhydride. An acid, glycerol tris trimellitic anhydride and the like can be used, but not limited thereto.

The component (b) of the component [B] is a solid, but when it is dispersed in an epoxy resin in the form of a powder, the component (B) has a low solubility in the epoxy resin, so that it cannot be dissolved at a curing temperature of 135 ° C. And sufficient curability cannot be obtained. For this reason, it is preferable that the blend of at least one of the constituent elements [A] and the constituent element [B] is uniformly dissolved at room temperature and is in a liquid state. From this point, as the component (a) of the component [B], methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride are used because the solubility of the component (b) of the component [B] is high. It is preferably used because of its high degree of freedom.

As the component (b) of the component [B], biphenyltetracarboxylic anhydride and ethylene glycol bisanhydride trimellitate can be used because of the high solubility of the component [B] in the component (a). Acids and glycerol tris trimellitic anhydride are preferably used. in this way,
By combining (a) an acid anhydride which is liquid at room temperature and (b) an acid anhydride having two or more acid anhydride groups in one molecule as a constituent element [B], a curing temperature of 135 ° C. This is an effect that a cured product that is cured and has a high crosslinking density can be obtained.

A cured product obtained by curing this composition at 135 ° C. for 2 hours has sufficient curability.
As a result, a decrease in physical properties at a high temperature can be suppressed low. However, in order to maintain the physical properties at a sufficiently high temperature, it is more preferable that the curing reaction rate is 85% or more under such curing conditions.

The cured product obtained by curing this composition has the characteristics of exhibiting low water absorption and low deterioration in physical properties upon water absorption.
In order to maintain sufficient mechanical properties after water absorption, 100 ° C
Is preferably 3% by weight or less, more preferably 2.5% by weight or less, after being immersed in boiling water for 20 hours.

[0025] Another characteristic of such a compound is that the decrease in mechanical properties at high temperatures during water absorption is suppressed.
In order to maintain sufficient mechanical properties in such a high temperature state of water absorption, it is preferable that the rigidity of the water-absorbing sample at 82 ° C. determined by a dynamic viscoelasticity test is 0.8 GPa or more.

In the component [B], the weight ratio of (a) and (b) is preferably in the range of (a) / (b) = 10 to 0.5. If the weight ratio of (a) and (b) is more than 10, the curability is good, but the crosslink density is low, and the heat resistance of the cured product is insufficient. From the viewpoint of heat resistance, the smaller the weight ratio of (a) and (b), the higher the crosslink density, which is preferable. Particularly, in applications such as aircraft structural materials that require high heat resistance, (a) and (b) The weight ratio of (b) is preferably 2.2 or less. If it is less than 0.5, the blend of the component [A] and the component [B] does not form a uniform dissolved state at room temperature, and it is difficult to obtain sufficient curability at 135 ° C.

Further, the equivalent ratio of the epoxy group in component [A] to the acid anhydride group in component [B] is preferably in the range of 0.5 to 1.1. If the equivalent ratio is out of the range, the rigidity of the resin decreases, which is not preferable. A more preferred equivalent ratio is in the range of 0.7 to 1.0.

The particles of the amine compound of the component [C] of the present invention are particles of the amine compound alone or of the amine compound and other components, and are solid at room temperature and substantially insoluble in the epoxy resin. Some are preferred. If the particle size is small, the surface area of the particles of the amine-based compound is relatively large, promotes the reaction between the epoxy resin and the acid anhydride during storage, and impairs the storage stability of the resin composition,
The amine compound used in the present invention preferably has an average particle size of 1 μm or more.

The composition of the present invention is excellent in storage stability, but when left in a constant-temperature apparatus at 40 ° C., 1 day after
Those having a glass transition temperature (Tg) increase of 10 ° C. or less after 0 days are particularly preferred.

When a composite material is prepared using a resin composition containing particles of an amine compound as a matrix resin, particles having a large particle size do not enter the reinforcing fiber bundle. The amount of the curing accelerator decreases, and the curing reaction rate becomes partially insufficient. Such a phenomenon is not preferable because it causes an increase in water absorption of the composite material after curing and a decrease in compressive strength after water absorption.

For this reason, in the present invention, it is necessary that the particles composed of the amine compound have an average particle diameter of 12 μm or less, and more preferably 10 μm or less. When the average particle size is 12 μm or less, the matrix resin in the fiber-reinforced composite material exhibits a uniform and high curing reaction rate, and the cured composite material has low water absorption and high rigidity. In the present invention, since the particles of the amine compound having a large particle size do not enter the reinforcing fiber bundle as described above, it is preferable that particles having a particle size of 20 μm or more be 10% or less.

The amine compound is solid at ordinary temperature,
When it is almost insoluble in the epoxy resin, it can be used as it is. Further, a combination of an amine compound and another component, for example, a thermoplastic resin, a thermosetting resin, or the like, which is modified or modified into particles satisfying the above conditions, may be used.

It is preferable to use a thermoplastic resin as a resin to be combined with such an amine compound, because it has an effect of improving the toughness of the cured resin. When an amine compound and a thermoplastic resin are combined, a resin that is softened at the curing temperature of the epoxy resin composition or that dissolves in the epoxy resin is preferably used. Although the softening point of the resin itself is particularly high, it is most preferable to use a resin that dissolves in the epoxy resin at the curing temperature, since there is no fear of impairing the heat resistance of the epoxy resin. As such a resin, for example, polyethersulfone, polyetherimide, or the like can be used.

A microcapsule type having an amine compound as a core layer can also be used. Specific examples of such microcapsule-type amine compounds that are commercially available include Novacure (trade name, manufactured by Asahi Kasei Corporation).

Such an amine compound can be combined with an inorganic substance. For example, a method of pulverizing a mixture of an amine compound and inorganic fine particles, a method of adsorbing and coating inorganic fine particles on the surface of an amine compound, a method of embedding an amine compound in inorganic hollow particles, and a porous mineral such as zeolite Particles formed by a method of adsorbing amine compound molecules between pores of a layer or between layers of a layered mineral such as montmorillonite can be used.

When the amine compound is combined with other components, the content of the amine compound in the particles is preferably 5% by weight or more, more preferably 20% by weight or more. If the content is less than 5% by weight, the curing reaction rate becomes insufficient and the water absorption increases, which is not preferable.

As such an amine compound, an organic compound having a structure selected from a primary amine, a secondary amine, a tertiary amine, an imine, and a heterocyclic ring containing a basic nitrogen can be used. Specifically, compounds such as those shown below can be used, but are not limited thereto.

First, examples of the aliphatic amine include ethylenediamine, propylenediamine, hexamethylenediamine, 2,5-dimethyl-2,5-hexanediamine, 2,2,4-trimethylhexamethylenediamine, and the like.
Diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine,
-Aminomethyloctamethylenediamine, 3-dimethylaminopropylamine, 3-diethylaminopropylamine, mentendiamine, isophoronediamine, aminoethylethanolamine, methyliminobispropylamine, bis (4-aminocyclohexyl) methane, or polyaminoamide For example, a high-molecular-weight type such as, for example, can be used.

As the aromatic amine, for example, 4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4-diaminodiphenylmethane, 4,4'-
Diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, diaminotoluene, xylylenediamine, dimethylbenzylamine, tris (dimethylaminomethyl) phenol, or a polymer such as aniline derivative and formaldehyde A molecular type or the like can be used.

Next, as the imine-based compound, for example, a compound obtained by reacting a primary amine with an aldehyde or a ketone, a ketimine usually obtained by a reaction with a ketone, or the like can be mainly used.

Next, examples of the heterocycle containing a basic nitrogen include pyridine, piperidine, piperazine, pyrrole, pyrrolidine, pyrroline, imidazole, imidazolidine,
Imidazoline, pyrazole, oxazole, oxazoline, pyrazine, pyrimidine, indole, purine, quinoline, quinoxaline, quinuclidine, morpholine, 1,
4-diazabicyclo [2,2,2] octane, 1,8-
Examples thereof include diazabicyclo [5,4,0] undecane, and these and their substituent derivatives can be used. Further, a polymer type such as polyvinyl pyridine can also be used.

Of these amine compounds, the amine compounds preferably do not have active hydrogen on the nitrogen atom in order not to lower the crosslink density of the cured epoxy-anhydride. In addition, imidazole compounds are particularly preferably used because the effect of accelerating the curing reaction between the epoxy resin and the acid anhydride by heating at 135 ° C. is sufficiently high. As the imidazole compound, an imidazole derivative having a substituent at the 1-position shown in the following general formula (2) can be used.
The imidazole derivative having a substituent at the 1-position has high reactivity and impairs the storage stability, and thus has rarely been used in a one-pack type epoxy resin composition for a composite material. However, when an imidazole derivative having a substituent at the 1-position is used as the amine compound of the component [C] in the epoxy resin composition of the present invention, a composition having extremely excellent storage stability can be obtained.

[0043]

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In the formula, R1 and R2 are unsubstituted or alkyl, aryl or aralkyl having one or more substituents selected from halogen, hydroxyl and cyano, and R3 and R4 are unsubstituted Or halogen, hydroxyl,
Represents an alkyl group, an aryl group, an aralkyl group or a hydrogen atom having one or more substituents selected from a cyano group. Here, the alkyl group means a substituent derived from a saturated hydrocarbon, and may be linear, branched, or have a cyclic structure. An aryl group is a substituent derived from an aromatic hydrocarbon and means one having a free valence on an aromatic ring, and one having only an aromatic ring such as a phenyl group or an aromatic group such as a tolyl group. It may have a group hydrocarbon structure as a partial structure. The aralkyl group means an unsubstituted aryl group or an alkyl group having one or more substituents selected from halogen, hydroxyl group, and cyano group, an alkyl group having an aryl group or an aralkyl group as a substituent.

Specific examples of the imidazole derivative represented by the above formula include 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-methylimidazole, 1- (2- (Cyanoethyl) -2-methylimidazole, 1- (2-cyanoethyl) -2-ethylimidazole, 1- (2-cyanoethyl) -2-isopropylimidazole, 1- (2-cyanoethyl) -2-undecylimidazole, 1- (2-
Cyanoethyl) -2-heptadecylimidazole, 1-
(2-cyanoethyl) -2-phenylimidazole, 1
-(2-cyanoethyl) -2-ethyl-4-methylimidazole, 1- (2-cyanoethyl) -2-ethyl-5
-Methyl imidazole or the like can be used.

As the imidazole derivative having a substituent at the 1-position, an adduct obtained by reacting an imidazole derivative having no substituent at the 1-position with an epoxy compound as shown in the following general formula (3) is particularly preferable. .

[0047]

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In the formula, R5 represents an unsubstituted or alkyl, aryl, or aralkyl group having one or more substituents selected from halogen, hydroxyl, and cyano.
6 to R7 represent an alkyl group, an aryl group, an aralkyl group or a hydrogen atom which is unsubstituted or has one or more substituents selected from halogen, hydroxyl group and cyano group.
When an imidazole derivative having no substituent at the 1-position and an adduct obtained by the reaction of an epoxy compound are used as the amine compound of the component [C] in the epoxy resin composition for a composite material of the present invention, 135 At a temperature of 2 ° C. for 2 hours.
An epoxy resin composition having a high rigidity of 0.8 GPa or more even after immersion for a long time can be obtained.

In general, imidazole compounds often have a problem of low storage stability due to their high reactivity. However, when an adduct obtained by the reaction of the imidazole derivative and the epoxy compound is used in combination with a borate compound, excellent storage stability is obtained. Also,
The cured product of the adduct of the imidazole derivative and the epoxy compound has a preferable property of low water absorption.

When the above-mentioned adduct is used as the component [C] of the present invention, the compounding amount may be in the range of 0.5 to 20 with respect to the weight 100 of the epoxy resin of the component [A]. preferable. If it is 0.5 or less, the curing reaction rate after heating becomes insufficient. If it is 20 or more, there is a problem that storage stability is reduced.

Specific examples of the imidazole derivative used for the synthesis of the adduct include 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, and 2-phenylimidazole. -Ethyl-4-methylimidazole,
4,5-bishydroxymethyl-2-phenylimidazole, 5-hydroxymethyl-4-methyl-2-phenylimidazole, 4-benzyl-5-hydroxymethyl-2-phenylimidazole, 4,5-bishydroxymethyl-2 -Phenylimidazole and the like can be used.

Specific examples of the epoxy compound used for the synthesis of the adduct include monoepoxy compounds such as phenylglycidyl ether and butylglycidyl ether, and diepoxy compounds such as bisphenol A epoxy resin and bisphenol F epoxy resin. it can.

As an adduct obtained by preliminarily reacting the imidazole derivative with the epoxy compound, those commercially available from Shikoku Chemicals Co., Ltd. under the trade name "Cureduct P-0505" can be used. In addition, epoxy compounds, urea compounds, and isocyanate compounds are adducted with amine compounds. Ajinomoto Co., Ltd .: Amicure, Fuji Chemical Co., Ltd .:
Product name “Fuji Cure”, ACR Corporation: Product name “AC
A commercially available product such as "R hardener" can be used.

In the epoxy resin composition of the present invention, a boric acid ester compound can be present as the constituent element [D]. By the presence of such a compound,
The amine compound becomes a complex with the borate compound on the particle surface and loses its activity as a curing agent or a curing catalyst. Thereby, the storage stability of the resin composition and the prepreg using the same can be significantly improved.

As the boric acid ester compound of the component [D], a compound represented by the following general formula can be used, and is used as a surface treating agent for the amine compound of the above component C. .

B (OR ₈ ) (OR ₉ ) (OR ₁₀ ) (wherein R _{8 to} R ₁₀ represent an alkyl group, an aralkyl group, or an aryl group). Is
Trimethyl borate, Triethyl borate, Tripropyl borate, Triisopropyl borate, Tributyl borate, Triisobutyl borate, Tripentyl borate, Trihexyl borate, Trioctyl borate , Trihexadecyl borate, trioctadecyl borate, tricresyl borate, trihexadecyl borate, tricyclohexyl borate, triphenyl borate, tritolyl borate, tribenzyl borate, Boric acid dimethyl ester, boric acid diethyl ester, boric acid monomethyl ester and the like can be used. These borate compounds are toxic and have no particular problem in metal corrosion.

These borate compounds may be used alone or in combination with a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a zircoaluminate coupling agent, or the like. No problem.

Further, an additive such as a phenol compound may be added for controlling the addition reaction of the amine compound or preventing oxidation. As the phenolic compound to be added, compounds such as pyrogallol and phenolic resin, and hindered phenolic antioxidants and tocopherol antioxidants are used.

A mixture of a boric acid ester compound, an epoxy resin and a phenol resin in advance is commercially available from Shikoku Chemicals Co., Ltd. under the trade names "Cureduct L-01B" and "Cureduct L-07N". For the preparation of the epoxy resin composition of the present invention, such commercially available products can also be used.

The epoxy resin composition of the present invention can be obtained by kneading particles containing an amine compound, which has been previously surface-treated with a borate compound, with an epoxy resin and other raw materials. As a method of the surface treatment, a method of stirring in a mixer or a method of contacting in a gas stream type pulverizer or a gas stream type classifier as described in JP-A-6-73156 is used. The epoxy resin composition of the present invention can also be obtained by separately adding an amine compound and a borate compound to an epoxy resin and other raw materials, followed by stirring and kneading. In the case of this production method, since the borate compound has no reactivity with the epoxy resin, the surface of the particles composed of the amine compound is treated with the borate compound in the epoxy resin. It also suggests that even if the surface treatment of the particles made of the amine compound is broken during kneading, the particles can be repaired.

The epoxy resin composition for a composite material of the present invention may contain other curing agents, thermoplastic resins, elastomers, thermoplastic elastomers and the like in addition to the epoxy resin, the amine compound and the borate compound. it can.

When other curing agents are blended, the curing agent is not particularly limited, but it is preferable that the curing reaction is accelerated or catalyzed by the above-mentioned amine compound.

The epoxy resin composition for a composite material of the present invention may contain a thermoplastic resin, an elastomer, a thermoplastic elastomer, etc. in addition to the epoxy resin, the amine compound and the borate compound.

The thermoplastic resin, the elastomer and the thermoplastic elastomer are used for controlling the viscosity of the epoxy resin composition, adjusting the tackiness of the prepreg, controlling the flow in the curing process,
It is added for the purpose of improving the toughness of the cured product and the adhesiveness with the reinforcing fiber.

The thermoplastic resin is not particularly limited, but those which can be easily dissolved in the epoxy resin are preferably used. In addition, a thermoplastic resin insoluble in an epoxy resin can be blended as long as it is finely divided. Specifically, acrylic resin, phenoxy resin, polyvinyl acetal, polyester, polycarbonate,
Polysulfone, polyarylene oxide, polyamide,
Polyimide or the like is used. Polyvinyl acetal is a resin obtained by acetalizing polyvinyl alcohol with a carbonyl compound such as formaldehyde or acetaldehyde, and polyvinyl formal or polyvinyl acetal can be used. As the phenoxy resin, a resin obtained by condensing bisphenol A and epochlorohydrin can be used. As the polyester, a polymer having a carboxylic acid ester bonded to the main chain can be used. Polycarbonate is a polymer having a carbonate bond in the main chain, and bisphenol A carbonate can be used as a typical example. As the polyarylene oxide, a resin having a main chain structure in which aromatic divalent groups and oxygen atoms are alternately arranged can be used. As the polysulfone, a resin having a sulfonyl group in the main chain can be used. In addition, those having an ether bond or the like in the main chain may be used. Polyamide is a resin having a carboxylic acid amide in the main chain. As the polyimide, a resin having a dicarboxylic imide structure in the main chain can be used. Others may have an ether bond or an amide bond. The acrylic resin is a polymer of an acrylate or a methacrylate, and a typical example is polymethyl methacrylate.

Of these, polysulfone, polyarylene oxide and polyimide are preferably used for applications requiring heat resistance. Polyvinyl formal is effective in controlling the flow of resin and improving the tackiness of the prepreg, and polysulfone and polyvinyl formal are effective in improving the adhesiveness with carbon fiber and the interlaminar shear strength and compressive strength. Is added when is required.

As the elastomer, a copolymer using acrylonitrile and butadiene as raw materials is preferably used because of its excellent solubility in an epoxy resin. Especially,
It is preferable to use an epoxy resin such as a carboxyl group, an amino group, or an epoxy group or a resin having a functional group capable of reacting with a curing agent thereof, since the effect of improving the toughness of the cured product is large.

Further, particles containing an epoxy resin-insoluble elastomer phase can also be preferably used. Although the crosslinked elastomer particles themselves can be used,
Core-shell type elastomer particles obtained by coating the surfaces of epoxy resin-insoluble elastomer particles with a non-elastomer component can be particularly preferably used. In this case, the component to be coated may be one which dissolves or swells in the epoxy resin like polymethyl methacrylate, and is more preferable because the particles can be well dispersed in the epoxy resin. When particles containing an epoxy resin-insoluble elastomer phase are used, the heat resistance of the cured resin is superior to that of a normal elastomer.

The addition of these elastomers has the effect of improving the toughness and the tackiness of the prepreg. In particular, when fine core-shell type elastomer particles having a particle size of about 0.1 to 0.3 μm are blended, the effect of improving toughness is remarkable.

As the thermoplastic elastomer, an elastomer which is easily dissolved in an epoxy resin is preferably used. Specifically, a block copolymer having a polyether structure as a soft segment and an aromatic polyester or aliphatic polyamide structure as a hard segment is preferable. The addition of these thermoplastic elastomers has the effect of improving the toughness of the cured product, and improving the tackiness when used as a matrix resin of a prepreg. Further, the heat resistance of the cured product is superior to the case where a normal elastomer is added.

The epoxy resin composition for a fiber-reinforced composite material of the present invention may further contain inorganic particles such as silica, alumina, titanium oxide, zirconia, clay mineral, talc, mica, and ferrite. These additions include:
It has the effect of increasing the viscosity of the resin composition, reducing the flow of the resin, adjusting the viscosity, improving the elastic modulus and heat resistance of the cured resin, and improving the wear resistance.

As a method for obtaining a fiber-reinforced composite material directly from an epoxy resin for a fiber-reinforced composite material and a reinforcing fiber, an epoxy resin composition is applied to a woven fabric or mat of a reinforcing fiber, and impregnated with a roller or the like under pressure. After that, the wet lay-up method of heating and curing, the reinforcing fiber bundle is impregnated with the epoxy resin composition, wound around a mold called a mandrel, heated and molded by the filament winding method, while the reinforcing fiber is impregnated with the epoxy resin composition. The product is supplied to a heating die having a predetermined shape, and is continuously formed. By performing shaping and heat curing to obtain a product, a pultrusion method is used. A method such as a resin transfer molding method in which the epoxy resin composition is placed in a mold and injected into the mold and cured. It can be used. Conventionally, in these methods, a two-pack type epoxy resin composition is often used, and since the pot life after the two-pack mixing is short, there are many process restrictions, but the epoxy resin composition of the present invention is Since it can be used as a single solution and there is no practical limitation on the pot life, there is a great advantage in terms of process flexibility. Because the intermediate substrate impregnated with the reinforcing fiber of the fiber-reinforced composite material epoxy resin of the present invention is excellent in storage stability,
It is preferably used as a raw material of a fiber-reinforced composite material.
As an intermediate substrate composed of an epoxy resin and a reinforcing fiber for a fiber-reinforced composite material, an epoxy resin composition is supplied to a sheet forming machine together with a continuous fiber or a reinforcing fiber cut to a predetermined size, and pressure impregnated into the sheet-like intermediate substrate. Sheets for the sheet molding compound method, and long fibers, tow fabrics, mats, knits, braids and other reinforcing fibers aligned in one direction are impregnated with an uncured epoxy resin composition into sheets, tapes, or There is a so-called string-shaped prepreg, but the present invention is not limited to these. Since these use a one-pack type epoxy resin, the conventional ones have poor storage stability and require frozen storage. Since the epoxy resin composition of the present invention has excellent storage stability, it can be stored in a refrigerator or at room temperature, and is much easier to use than conventional products. The effect of the resin composition of the present invention is remarkable when prepreg is used.

For the production of a prepreg, for example, an epoxy resin composition is applied on release paper using a reverse roll coater or the like to form a resin film, and the resin film is stacked on one side or both sides of the reinforcing fiber and heated. For example, a method of impregnating the reinforcing fibers by applying pressure can be used.

As the reinforcing fibers, glass fibers, carbon fibers, aramid fibers, boron fibers, alumina fibers, silicon carbide fibers and the like are used. Among them, carbon fibers having excellent strength and elastic modulus and a small specific gravity are particularly preferable because a fiber-reinforced composite material having excellent specific strength and specific elastic modulus can be obtained.

As the form of the fiber of the intermediate base material, a long fiber having a length of 1 cm or more is preferable from the viewpoint of mechanical properties obtained in a molded product, and in a prepreg, the characteristics of the reinforcing fiber are most effectively used. For this reason, it is more preferable that the fiber is in the form of a continuous fiber or a mat having a unidirectional fiber direction.

The tensile strength of carbon fiber or graphite fiber is 44
A pressure of 00 MPa or more is preferable because a carbon fiber composite material having high tensile strength is provided. In addition, it is preferable that the tensile strength of the carbon fiber is 5000 MPa or more, because the strength becomes higher.

The tensile elongation of carbon fiber or graphite fiber is 1.
If it is 8% or more, it is preferable because a carbon fiber composite material having high tensile strength is provided.

Further, as the carbon fibers or graphite fibers suitable for the present invention, those having no twist and no twist and having a substantially circular cross section can be used. The twist and twist of the carbon fiber can be quantitatively represented by a hook drop value.
Here, the hook drop value is a temperature of 23 ° C. and a humidity of 60%.
Vertically suspended carbon fiber bundle in the atmosphere of 1m
mφ, a stainless wire with a length of about 100 mm, a lower part of 20 to 30 mm was bent and a load of 12 g was applied, and a stainless steel wire was hooked on a fiber bundle at a part bent into a U shape at the upper part of 20 to 30 mm, and after 30 minutes, It is a value that can be expressed by the falling distance of the load. This value decreases when there is twist or twist.

In general, carbon fibers are used in the production process.
In order to prevent process troubles such as winding of broken filaments around rollers, and in prepreg production, creels, guides and combs for carbon fiber supply suppress the spread of carbon fibers and give convergence to improve passage. ing. To bundle the carbon fibers, there are a method of entanglement of the filaments of the fiber bundle, a method of twisting and bundling, releasing the twist after passing through the process, and a method of adhering a resin called a sizing agent.

However, when the carbon fibers are bundled, the processability is improved, but in the production of prepreg, the impregnating property of the matrix resin is reduced due to the convergence.
In the method of releasing after twisting, twisting into carbon fiber,
Since the twist remains, the produced prepreg is not smooth and has irregularities on the surface, which adversely affects the physical properties of the composite material.

The index of the convergence is the hook drop value. Increasing the hook drop value improves resin impregnating property and surface smoothness in prepreg production, but causes process troubles such as excessive spreading of carbon fiber with creels, guides and combs for carbon fiber supply, fuzz generation and poor passage. Easy to wake up. Preferred hook drop values are 100 cm or less. The carbon fiber of the present invention has a hook drop value of 10 cm or more and 100 cm or less, more preferably 12 cm or more and 100 cm or less.

The fiber reinforced resin intermediate substrate of the present invention preferably has a resin content of 20% to 50%. When the resin content is 20% or less, voids remain in the molded product after curing, and sufficient strength is not developed. When the resin content is 50% or more, the resin exudes much during heat curing and the orientation of fibers is disturbed, so that sufficient strength is obtained. This is because it is not expressed. A more preferred range is 30%
４０40%.

The fiber-reinforced resin intermediate substrate using the resin composition of the present invention achieves both a high curing reaction rate and stability during storage even at a temperature of 135 ° C. for about 2 hours, and has a high water absorption high temperature state. An object of the present invention is to provide a fiber-reinforced composite material having excellent strength.

[0084]

The present invention will be described below in more detail with reference to examples.

The curing reaction rate of the epoxy resin in the present invention is determined by infrared absorption measurement. Specifically, the curing reaction rate is determined from the change in the relative ratio between the absorption peak of the epoxy group (920 cm ^-1 ) and the absorption peak of the phenylene group (870 cm ^-1 ). As a measurement sample, an uncured resin or a cured resin mixed with potassium bromide and then used as a tablet is used.

The water absorption of the cured resin in the present invention is 1
Weight of sample dried at 20 ° C for 20 hours and 100 ° C
Is determined from the difference in weight of the water-absorbed sample after immersion in boiling water for 20 hours. The dimensions of the sample are 2 mm in thickness, 10 mm in width, and 5 cm in length.

The rigidity of the cured resin in the present invention is determined by dynamic viscoelasticity measurement. Specific measurement conditions are as follows: frequency = 3.14 rad / s, heating rate = 5 ° C./min, strain =
0.1%, measurement start temperature = 30 ° C. The dimensions of the sample are 2 mm thick, 10 mm wide and 5 cm long, as in the measurement of water absorption. As a dry sample, a sample subjected to heat treatment at 120 ° C. for 20 hours is used. As the water absorption sample, 1
What was immersed in the boiling water of 00 degreeC for 20 hours is used. The dynamic viscoelasticity measurement of a water-absorbing sample is performed immediately after the sample is taken out of boiling water.

The prepreg of the present invention is manufactured as follows.

First, the prepared epoxy resin composition was mixed with 1
Heat and cure at 35 ° C. for 2 hours.

Next, the epoxy resin composition is applied to release paper using a film coater to prepare a resin film. This resin film is aligned in one direction to form a sheet-like carbon fiber (Torayca T800H: Toray Industries, Inc.)
190g / m ² ) impregnated with heat and pressure from both sides
Get prepreg.

[0091] Six prepregs are laminated and cured under pressure at 135 ° C for 2 hours in an autoclave.

In these examples and comparative examples, all parts described in the examples and comparative examples are parts by weight. Table 1 shows the main physical properties of the main raw material resin and the resin composition (uncured), and Table 2 shows the physical properties of the cured resin and the composite material. Example 1 An epoxy resin composition was obtained by mixing the following materials. Bisphenol A type epoxy resin Epicoat 828 (Epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 100 parts Mixture of glycerol tris trimellitic anhydride and methylhexahydrophthalic anhydride Ricacid MTA-15 (acid anhydride equivalent) : 180, manufactured by Shin-Nippon Rika Co., Ltd.) 95 parts-Additive of imidazole and bisphenol A type epoxy resin Cureduct P-0505 (manufactured by Shikoku Chemical Industry Co., Ltd.) 2 parts (average particle size: 2.1 μm)-Ho Mixture of acid tributyl ester, phenolic resin and bisphenol A type epoxy resin Cureduct L-07N (manufactured by Shikoku Kasei Kogyo Co., Ltd.) 1 part When the above epoxy composition is allowed to stand in a thermostat at 40 ° C., one day later The change of the glass transition temperature (Tg) after 10 days from the above was measured by DSC method. There has been confirmed (after one day Tg: -15 ℃, after 10 days Tg: -11 ℃).

The above epoxy resin composition was heated at 135 ° C. for 2 hours.
Heat cured for hours. The curing reaction rate was 93%, and the glass transition temperature was 140 ° C. when measured by the DSC method. Further, the rigidity at 30 ° C. was 1.23 GPa. The water absorption of the cured resin was 1.76%, and the rigidity at 82 ° C. in the water absorbing state was 0.99 GPa.

Next, a prepreg was obtained from the epoxy resin composition according to the method described above.

Six prepregs were laminated and pressure-cured in an autoclave at 135 ° C. for 2 hours to obtain a fiber-reinforced composite material. When the 0 ° tensile strength of this composite material was measured, it was 2310 MPa. The 0 ° compression strength of this composite material in a dry state at room temperature is 1410MPa.
a, The 0 ° compressive strength in a high-temperature moisture absorbing state was 1150 MPa. Example 2 The following materials were mixed to obtain an epoxy resin composition. -Bisphenol A type epoxy resin Epicoat 828 (Epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 70 parts-Dicyclopentadiene type epoxy resin HP-7200H (Epoxy equivalent: 283, manufactured by Dainippon Ink & Chemicals, Inc.) 30 parts)-Glycerol tris trimellitic anhydride licacid TMTA-C (acid anhydride equivalent: 205, manufactured by Shin Nippon Rika Co., Ltd.) 35 parts-Methyl hexahydrophthalic anhydride licacid MH-700 (acid anhydride equivalent: 168) , Manufactured by Shin Nippon Rika Co., Ltd.) 48 parts ・ Amine addition type curing agent AMICURE MY-24 (manufactured by Ajinomoto Co., Inc.) 3 parts When the above epoxy composition is allowed to stand in a thermostat at 40 ° C., one day later Change in glass transition temperature after 10 days is DS
Examination by Method C revealed an increase of 3 ° C (Tg after 1 day: -11 ° C, Tg after 10 days: -8 ° C).

The above epoxy resin composition was heated at 135 ° C. for 2 hours.
Heat cured for hours. The curing reaction rate of the cured product is 91
%, And the glass transition temperature was measured by the DSC method.
2 ° C. The rigidity at 30 ° C is 1.31GP.
a. The water absorption of the cured resin is 1.82%,
The rigidity at 82 ° C. in the water absorbing state was 1.02 GPa.

Next, a prepreg was obtained from the epoxy resin composition according to the method of Example 1 and then molded to obtain a fiber-reinforced composite material, and various physical properties were measured. Example 3 The following materials were mixed to obtain an epoxy resin composition. -Bisphenol A type epoxy resin Epicoat 828 (Epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 90 parts-Cyclohexanedimethanol diglycidyl ether herooxy MK-107 (Epoxy equivalent: 165, manufactured by Shell Chemical Co., Ltd.) 10 Part ・ glycerol tris trimellitic anhydride licacid TMTA-C (acid anhydride equivalent: 205, manufactured by Shin Nippon Rika Co., Ltd.) 39 parts ・ methyl hexahydrophthalic anhydride licacid MH-700 (acid anhydride equivalent: 168, new Nippon Rika Co., Ltd.) 54 parts ・ Microcapsule type hardener Novacure HX-3722 (Asahi Kasei Kogyo Co., Ltd.) 6 parts When the above epoxy composition is allowed to stand in a thermostat at 40 ° C., 1 day to 10 days later Change of glass transition temperature of
When examined by Method C, an increase of 5 ° C. was confirmed (Tg after 1 day: −12 ° C., Tg after 10 days: −7 ° C.).

The above epoxy resin composition was heated at 135 ° C. for 2 hours.
Heat cured for hours. The curing reaction rate of the cured product is 90
%, And the glass transition temperature was measured by the DSC method.
9 ° C. The rigidity at 30 ° C. is 1.18 GP.
a. The water absorption of the cured resin is 1.97%,
The rigidity at 82 ° C. in a water-absorbing state was 0.96 GPa.

Next, a prepreg was obtained from the epoxy resin composition according to the method of Example 1 and then molded to obtain a fiber-reinforced composite material, and various physical properties were measured. Example 4 The following materials were mixed to obtain an epoxy resin composition. -Bisphenol A type epoxy resin Epicoat 828 (Epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 70 parts-Dicyclopentadiene type epoxy resin HP-7200H (Epoxy equivalent: 283, manufactured by Dainippon Ink & Chemicals, Inc.) 30 parts) Glycerol tris trimellitic anhydride licacid TMTA-C (acid anhydride equivalent: 205, manufactured by Shin Nippon Rika Co., Ltd.) 39 parts Methyl hexahydrophthalic anhydride licacid MH-700 (acid anhydride equivalent: 168) 54 parts ・ Adduct of imidazole and bisphenol A type epoxy resin Cure duct P-0505 (manufactured by Shikoku Chemicals) 2 parts (average particle size 2.1 μm) ・ Tributyl borate Mixture of ester, phenolic resin and bisphenol A type epoxy resin L-01B when standing (Shikoku Chemicals Co., Ltd.) 1 part epoxy compositions in a thermostatic apparatus 40 ° C., the glass transition temperature change after 10 days from one day after DSC
As a result, a rise of 4 ° C. was confirmed (T 1 day later).
g: -15 ° C, Tg after 10 days): -11 ° C).

The above epoxy resin composition was heated at 135 ° C. for 2 hours.
Heat cured for hours. The curing reaction rate of the cured product is 89
%, And the glass transition temperature was measured by the DSC method.
2 ° C. The rigidity at 30 ° C is 1.23GP.
a. The water absorption of the cured resin is 1.97%,
The rigidity at 82 ° C. in the water absorbing state was 1.02 GPa.

Next, a prepreg was obtained from the epoxy resin composition according to the method of Example 1, and then molded to obtain a fiber-reinforced composite material, and various physical properties were measured. (Example 5) (1) Preparation of imidazole-containing particles 25 parts of 1-benzyl-2-phenylimidazole and 75 parts of 1000 polyetherimide ultem are dissolved in 675 parts of methylene chloride and, while stirring at 3000 rpm, higher alcohol sulfate ester Soda (Monogen Y
An aqueous solution in which 1% by weight of -100 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was dissolved was gradually added to obtain an emulsion solution. Next, the mixture was gradually heated at 60 ° C. while stirring at 15 rpm, and methylene chloride was removed over 2 hours to obtain an aqueous dispersion of fine particles. The dispersion was filtered, washed, and vacuum dried at room temperature for 24 hours to obtain imidazole-containing particles. The average particle size was 4 μm, and 0% of the particles had a particle size of 10 μm or more. (2) Preparation of epoxy resin composition The following materials were mixed to obtain an epoxy resin composition. -Bisphenol A type epoxy resin Epicoat 828 (epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 70 parts-Trimethylolpropane type epoxy resin Epototo YH-300 (epoxy equivalent: 144, manufactured by Toto Kasei Co., Ltd.) 30 Part: glycerol tris trimellitic anhydride licacid MH-700 (acid anhydride equivalent: 168, manufactured by Shin Nippon Rika Co., Ltd.) 57 parts: benzophenone tetracarboxylic anhydride BTDA (acid anhydride equivalent: 161, manufactured by Gulf) 38 parts ・ Imidazole-containing particles prepared in (1) 3 parts When the epoxy composition was allowed to stand in a thermostat at 40 ° C., the change in glass transition temperature after 1 day to 10 days was determined by DS.
When examined by Method C, an increase of 6 ° C. was confirmed (Tg after 1 day: −15 ° C., Tg after 10 days: −9 ° C.).

The above epoxy resin composition was heated at 135 ° C. for 2 hours.
Heat cured for hours. The curing reaction rate of the cured product is 93.
%, And the glass transition temperature was measured by the DSC method.
8 ° C. The rigidity at 30 ° C. is 1.19 GP.
a. The water absorption of the cured resin is 2.02%,
The rigidity at 82 ° C. in the water absorbing state was 1.00 GPa.

Next, a prepreg was obtained from the epoxy resin composition according to the method of Example 1 and then molded to obtain a fiber-reinforced composite material, and various physical properties were measured. Example 6 The following materials were mixed to obtain an epoxy resin composition. -Bisphenol A type epoxy resin Epicoat 828 (epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 70 parts-Phenol novolak type epoxy resin Epicoat 154 (epoxy equivalent: 178, manufactured by Yuka Shell Epoxy Co., Ltd.) 30 parts Glycerol tris Trimellitic anhydride and methyl hexahydrophthalic anhydride mixture Ricacid MTA-15 (acid anhydride equivalent: 180, manufactured by Shin Nippon Rika Co., Ltd.) 100 parts Microcapsule type hardener Novacure HX-3722 (Asahi Kasei When the epoxy composition was allowed to stand in a thermostat at 40 ° C., the glass transition temperature change after 1 day to 10 days was measured by DSC.
As a result, a rise of 4 ° C. was confirmed (T 1 day later).
g: -15 ° C, Tg after 10 days): -11 ° C).

The above epoxy resin composition was heated at 135 ° C. for 2 hours.
Heat cured for hours. The curing reaction rate of the cured product is 93.
%, And the glass transition temperature was measured by the DSC method.
6 ° C. The rigidity at 30 ° C. is 1.18 GP.
a. The water absorption of the cured resin is 2.02%,
The rigidity at 82 ° C. in a water-absorbing state was 1.06 GPa.

Next, a prepreg was obtained from the epoxy resin composition according to the method of Example 1 and then molded to obtain a fiber-reinforced composite material, and various physical properties were measured. Example 7 The following materials were mixed to obtain an epoxy resin composition. -Bisphenol A type epoxy resin Epicoat 828 (epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 70 parts-Phenol novolak type epoxy resin Epicoat 154 (epoxy equivalent: 178, manufactured by Yuka Shell Epoxy Co., Ltd.) 30 parts Glycerol tris trimellitic anhydride licacid TMTA-C (acid anhydride equivalent: 205, manufactured by Shin Nippon Rika Co., Ltd.) 30 partsMethyl hexahydrophthalic anhydride licacid MH-700 (acid anhydride equivalent: 168, New Japan) Rika Co., Ltd.) 56 parts ・ Microcapsule type hardener Novacure HX-3722 (Asahi Kasei Corporation) 6 parts The above epoxy resin composition is applied to release paper using a film coater to produce a resin film. did. The basis weight of the resin film was 62 g / m ² .

The resin film was aligned in one direction and impregnated with heat and pressure from both sides of a sheet-like carbon fiber (Torayca T700S; manufactured by Toray Industries, Inc., weight: 190 g / m ² ) to obtain a prepreg.

Six prepregs were laminated and cured by pressure in an autoclave at 135 ° C. for 2 hours. The glass transition temperature was 151 ° C. as measured by DSC.

Next, various physical properties were measured according to the method of Example 1. Example 8 An epoxy resin composition was obtained by mixing the following materials. -Bisphenol F type epoxy resin Epicoat 828 (epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 60 parts-Dicyclopentadiene type epoxy resin HP-7200H (epoxy equivalent: 283, manufactured by Dainippon Ink & Chemicals, Inc.) Glycerol tris trimellitic anhydride licacid TMTA-C (acid anhydride equivalent: 205, manufactured by Shin Nippon Rika Co., Ltd.) 35 parts methylhexahydrophthalic anhydride licacid MH-700 (acid anhydride equivalent: 168) 48 parts of a microcapsule type hardener Novacure HX-3722 (manufactured by Asahi Chemical Industry Co., Ltd.) 6 parts The above epoxy resin composition was heat-cured at 135 ° C. for 2 hours. The curing reaction rate of the cured product was 87%, and the rigidity at 30 ° C. was 1.35 GPa. The water absorption of the cured resin was 2.56%, and the rigidity at 82 ° C. in the water absorbing state was 0.88 GPa.

Next, a prepreg was obtained from the epoxy resin composition according to the method of Example 1 and then molded to obtain a fiber-reinforced composite material, and various physical properties were measured. Example 9 The following materials were mixed to obtain an epoxy resin composition. -Bisphenol F type epoxy resin Epicron 830 (epoxy equivalent: 172, manufactured by Dainippon Ink and Chemicals, Inc.) 70 parts-Dicyclopentadiene type epoxy resin HP-7200H (epoxy equivalent: 283, Dainippon Ink and Chemicals, Inc.) Glycerol tris trimellitic anhydride licacid TMTA-C (acid anhydride equivalent: 205, manufactured by Shin Nippon Rika Co., Ltd.) 30 parts methylhexahydrophthalic anhydride licacid MH-700 (acid anhydride equivalent: 168, manufactured by Nippon Rika Co., Ltd.) 62 parts ・ Microcapsule type hardener NOVACURE HX-3722 (manufactured by Asahi Kasei Kogyo Co., Ltd.) 6 parts ・ Polymethyl methacrylate diamond BR-88 (manufactured by Mitsubishi Rayon Co., Ltd.) 2 parts ・ Polyetherimide Ultem 1000 (General Electric Company) ) 2 hours 15 parts of the epoxy resin composition at 135 ° C., heated and cured. The curing reaction rate was 91%, and the rigidity at 30 ° C. was 1.25 GPa. The water absorption of the cured resin is 1.83%, and the rigidity at 82 ° C. in the water absorbing state is 1.80%.
It was 05 GPa.

Next, the epoxy resin composition was applied to release paper using a film coater to prepare a resin film. The weight of the resin film was 52 g / m ² .
This resin film is aligned in one direction and formed into a sheet-like carbon fiber (Torayca T800H: manufactured by Toray Industries, Inc.,
90 g / m ² ) was impregnated with heat and pressure from both sides to obtain a prepreg.

[0111] Six prepregs were laminated and cured under pressure at 135 ° C for 2 hours in an autoclave to obtain a fiber-reinforced composite material. When the 0 ° tensile strength of this composite material was measured, it was 2290 MPa. Also, the 0 ° compression strength of this composite material in a dry state at room temperature is 1390 MPa.
a, The 0 ° compressive strength in a high-temperature moisture absorbing state was 1110 MPa. Example 10 The following materials were mixed to obtain an epoxy resin composition. -Bisphenol F type epoxy resin Epicoat 828 (epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 30 parts-Dicyclopentadiene type epoxy resin HP-7200H (epoxy equivalent: 283, manufactured by Dainippon Ink & Chemicals, Inc.) Glycerol tris trimellitic anhydride licacid TMTA-C (acid anhydride equivalent: 205, manufactured by Shin Nippon Rika Co., Ltd.) 32 parts methylhexahydrophthalic anhydride licacid MH-700 (acid anhydride equivalent: 168) 43 parts. Microcapsule-type curing agent Novacure HX-3722 (manufactured by Asahi Kasei Kogyo Co., Ltd.) 6 parts The above epoxy resin composition was heat-cured at 135 ° C. for 2 hours. The curing reaction rate was 76%, and the rigidity at 30 ° C. was 1.31 Gpa. The water absorption of the cured resin was 3.13%, and the rigidity at 82 ° C. in the water absorbing state was 0.1%.
It was 82 GPa.

Next, a prepreg was obtained from the epoxy resin composition according to the method of Example 1 and then molded to obtain a fiber-reinforced composite material, and various physical properties were measured. Example 11 The following materials were mixed to obtain an epoxy resin composition. -Bisphenol F type epoxy resin Epicron 830 (epoxy equivalent: 172, manufactured by Dainippon Ink & Chemicals, Inc.) 30 parts-Dicyclopentadiene type epoxy resin HP-7200H (epoxy equivalent: 283, Dainippon Ink & Chemicals, Inc.) Glycerol tris trimellitic anhydride licacid TMTA-C (acid anhydride equivalent: 205, manufactured by Shin Nippon Rika Co., Ltd.) 24 parts methylhexahydrophthalic anhydride licacid MH-700 (acid anhydride equivalent: 168, manufactured by Shin Nippon Rika Co., Ltd.) 51 parts ・ Microcapsule type curing agent NOVACURE HX-3722 (manufactured by Asahi Chemical Industry Co., Ltd.) 6 parts ・ Polymethyl methacrylate diamond BR-88 (manufactured by Mitsubishi Rayon Co., Ltd.) 2 parts ・ Polyetherimide Ultem 1000 (General Electric Company) ) 15 parts of the epoxy resin composition of 135 ° C., and cured by heating at 2 hours. The curing reaction rate was 72%, and the rigidity at 30 ° C. was 1.26 Gpa. The water absorption of the cured resin was 3.03%, and the rigidity at 82 ° C. in the water absorbing state was 0.3%.
It was 83 GPa.

Next, the epoxy resin composition was applied to release paper using a film coater to prepare a resin film. The weight of the resin film was 52 g / m ² .
This resin film is aligned in one direction and formed into a sheet-like carbon fiber (Torayca T800H: manufactured by Toray Industries, Inc.,
90 g / m ² ) was impregnated with heat and pressure from both sides to obtain a prepreg.

Six prepregs were laminated and pressurized and cured in an autoclave at 135 ° C. for 2 hours to obtain a fiber-reinforced composite material. When the 0 ° tensile strength of this composite material was measured, it was 2150 MPa. The 0 ° compression strength of this composite material in a dry state at room temperature is 1180 MPa.
a, The 0 ° compressive strength in a high-temperature moisture absorbing state was 980 MPa. Comparative Example 1 An epoxy resin composition was obtained by mixing the following materials. -Bisphenol A type epoxy resin Epicoat 828 (Epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 60 parts-Tetraglycidyl diaminodiphenylmethane Sumiepoxy ELM-434 (manufactured by Sumitomo Chemical Co., Ltd.) 40 parts Mixture of melitic acid and methylhexahydrophthalic anhydride Ricacid MTA-15 (acid anhydride equivalent: 180, manufactured by Shin Nippon Rika Co., Ltd.) 116 parts-Adduct of imidazole and bisphenol A type epoxy resin Cure duct P-0505 ( Shikoku Chemical Industry Co., Ltd.) 2 parts (average particle size: 2.1 μm)-Mixture of tributyl borate, phenolic resin and bisphenol A type epoxy resin Cure duct L-07N (Shikoku Chemical Industry Co., Ltd.) 1 Part The above epoxy composition is kept at a constant temperature of 40 ° C. When allowed to stand, the glass transition temperature change after 10 days from one day after DSC
Method, a rise of 30 ° C. was confirmed (one day later T
g: -2 ° C, Tg after 10 days: 28 ° C), and the resin composition was solidified. Comparative Example 2 An epoxy resin composition was obtained by mixing the following materials. Bisphenol A type epoxy resin Epicoat 828 (epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 100 parts 89 parts) The epoxy resin composition was cured by heating at 135 ° C. for 2 hours. The curing reaction rate of the cured product was 93%, and the glass transition temperature was measured by a DSC method. The rigidity at 30 ° C is 0.89G.
Pa. The water absorption of the cured resin was 2.72.
%, The rigidity at 82 ° C. in a water absorbing state is 0.63 GP.
a.

Next, a prepreg was obtained from the epoxy resin composition according to the method of Example 1 and then molded to obtain a fiber-reinforced composite material, and various physical properties were measured. Comparative Example 3 The following materials were mixed to obtain an epoxy resin composition. -Bisphenol A type epoxy resin Epicoat 828 (Epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 70 parts-Dicyclopentadiene type epoxy resin HP-7200H (Epoxy equivalent: 283, manufactured by Dainippon Ink & Chemicals, Inc.) Glycerol tris trimellitic anhydride lycacid TMTA-C (acid anhydride equivalent: 205, manufactured by Shin Nippon Rika Co., Ltd.) 95 parts; amine addition type curing agent AMICURE MY-24 (manufactured by Ajinomoto Co., Ltd.) 3 Part The epoxy resin composition was cured by heating at 135 ° C. for 2 hours. The curing reaction rate of the cured product was 62%, and the glass transition temperature was measured by a DSC method. The rigidity at 30 ° C. is 1.35G.
Pa. The water absorption of the cured resin is 2.86.
%, The rigidity at 82 ° C. in a water absorbing state is 0.76 GP.
a.

Next, a prepreg was obtained from the epoxy resin composition according to the method of Example 1 and then molded to obtain a fiber-reinforced composite material, and various physical properties were measured. (Comparative Example 4) (1) Preparation of imidazole-containing particles 25 parts of 1-benzyl-2-phenylimidazole and 75 parts of polyetherimide (Ultem 1000, manufactured by GE Plastics Co., Ltd.) were dissolved in 675 parts of methylene chloride. While stirring at 500 rpm, 900 parts of an aqueous solution in which 1% by weight of higher alcohol sulfate ester soda (Monogen Y-100, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was dissolved was gradually added to obtain an emulsion solution. Next, the mixture was gradually heated at 60 ° C. while stirring at 15 rpm, and methylene chloride was removed over 2 hours to obtain an aqueous dispersion of fine particles. The dispersion was filtered, washed, and vacuum dried at room temperature for 24 hours to obtain imidazole-containing particles. The average particle size was 35 μm. (2) Preparation of epoxy resin composition The following materials were mixed to obtain an epoxy resin composition. -Bisphenol A type epoxy resin Epicoat 828 (epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 70 parts-Phenol novolak type epoxy resin Epicoat 154 (epoxy equivalent: 178, manufactured by Yuka Shell Epoxy Co., Ltd.) 30 parts Glycerol tris trimellitic anhydride licacid TMTA-C (acid anhydride equivalent: 205, manufactured by Shin Nippon Rika Co., Ltd.) 30 partsMethyl hexahydrophthalic anhydride licacid MH-700 (acid anhydride equivalent: 168, New Japan) Rika Co., Ltd.) 56 parts ・ Imidazole-containing particles prepared in (1) 3 parts The above epoxy resin composition was applied to release paper using a film coater to prepare a resin film. Vertical streaks due to coarse curing accelerator powder were observed in the resin film.

The resin film was aligned in one direction, and impregnated with heat and pressure from both sides of sheet-like carbon fiber (Torayca T700S; manufactured by Toray Industries, Inc., weight: 190 g / m ² ) to obtain a prepreg.

[0118] Six prepregs were laminated,
The glass transition temperature of the composite obtained by curing under the conditions of 2 hours was 98 ° C. as measured by the DSC method.

Next, various physical properties were measured according to the method of Example 1. (Comparative Example 5) (1) Pulverization of a curing accelerator 4,4'-dimethyldiphenyl sulfone (Sumicure S: manufactured by Sumitomo Chemical Co., Ltd.) was cooled with liquid nitrogen and freeze-pulverized using a hammer mill. Average particle size 0.6
A finely pulverized product of 5 μm was obtained. (2) Preparation of epoxy resin composition The following materials were mixed to obtain an epoxy resin composition. -Bisphenol A type epoxy resin Epicoat 828 (Epoxy equivalent: 189, manufactured by Yuka Shell Epoxy Co., Ltd.) 90 parts-Cyclohexanedimethanol diglycidyl ether herooxy MK-107 (Epoxy equivalent: 165, manufactured by Shell Chemical Co., Ltd.) 10 Part ・ glycerol tris trimellitic anhydride licacid TMTA-C (acid anhydride equivalent: 205, manufactured by Shin Nippon Rika Co., Ltd.) 39 parts ・ methyl hexahydrophthalic anhydride licacid MH-700 (acid anhydride equivalent: 168, new 54 parts ・ 4,4′-dimethyldiphenylsulfone finely pulverized product prepared in (1) 2 parts When the epoxy resin composition was allowed to stand in a thermostat at 40 ° C., one day later Change in glass transition temperature after 10 days is D
When examined by the SC method, an increase of 18 ° C. was confirmed (Tg after 1 day: −5 ° C., Tg after 10 days: 13 ° C.), and the resin composition was solidified.

[0120]

[Table 1]

[0121]

[Table 2]

[0122]

According to the present invention, a high curing reaction rate and stability during storage can be achieved at the same time even under curing conditions of heating at 135 ° C. for about 2 hours, and can be carried out in boiling water at 100 ° C. for 20 hours. Even after immersion, the cured product can provide an epoxy resin composition having a high rigidity.Furthermore, by using such an epoxy resin composition, a fiber-reinforced composite material having excellent strength in a high temperature state of water absorption can be stabilized. Can be provided.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI C08K 9/10 C08K 9/10

Claims (19)

[Claims] An epoxy resin composition for a fiber-reinforced composite material, comprising the following components: [A]: an epoxy resin comprising at least one selected from an alicyclic epoxy resin, an epoxy resin having an aromatic ring and containing no nitrogen atom, and a glycidyl ether of an aliphatic polyhydric alcohol [B]: (a) An acid anhydride which is liquid at room temperature and (b) an acid anhydride comprising an acid anhydride having two or more acid anhydride groups in one molecule [C]: an amine compound having an average particle diameter of 1 to 12 µm particle 2. The epoxy resin composition for a fiber-reinforced composite material according to claim 1, wherein a blend of at least one of the components [A] and the components [B] is liquid at room temperature. 3. The epoxy resin composition according to claim 1, wherein the diglycidyl ether type epoxy resin contained in the component [A] is 50% by weight or more based on the component [A]. . 4. One day after the composition of component [A], component [B] and component [C] mixed at a temperature equal to or lower than the curing initiation temperature is allowed to stand in a constant-temperature device at 40 ° C. The epoxy resin composition according to any one of claims 1 to 3, wherein a change in glass transition temperature after 10 days from the start is 10 ° C or less. 5. The resin composition according to claim 1, wherein the resin composition is cured by heating at 135 ° C. for 2 hours, and the curing reaction rate of the resin composition determined by infrared absorption measurement is 85% or more.
The epoxy resin composition according to any one of the above. 6. The method according to claim 1, wherein a cured resin obtained by heating at 135 ° C. for 2 hours has a water absorption of 3% by weight or less when immersed in boiling water at 100 ° C. for 20 hours. The epoxy resin composition according to the above. 7. A resin cured product formed by heating at 135 ° C. for 2 hours is immersed in boiling water at 100 ° C. for 20 hours, and the rigidity at 82 ° C. determined by dynamic viscoelasticity measurement is 0.8 GP.
The epoxy resin composition according to any one of claims 1 to 6, which is at least a. 8. The component [B], wherein the weight ratio of (a) and (b) is in the range of (a) / (b) = 10 to 0.5. The epoxy resin composition according to any one of items 1 to 7, 9. The component [B] according to claim 1, wherein the acid anhydride equivalent of (a) and (b) is in the range of 140 to 200. The epoxy resin composition according to the above. 10. An epoxy group in the component [A],
The equivalent ratio of the acid anhydride groups in the component [B] is in the range of 0.5 to 1.1.
10. The epoxy resin composition according to any one of 4, 8 and 9. 11. The epoxy resin composition for a fiber-reinforced composite material according to claim 1, wherein the particles comprising the amine compound comprise an amine compound and a thermoplastic resin. 12. The fiber reinforced material according to claim 1, wherein the amine compound is an imidazole derivative, and the imidazole derivative is an adduct of an imidazole derivative having no substituent at the 1-position and an epoxy compound. Epoxy resin composition for composite materials. 13. The epoxy resin composition for a fiber-reinforced composite material according to claim 1, wherein the amine compound is microencapsulated. 14. The fiber reinforcement according to claim 1, wherein the amount of the amine compound is 0.5 to 20 parts by weight based on 100 parts by weight of the epoxy resin. Epoxy resin composition for composite materials. 15. The epoxy resin composition for a fiber-reinforced composite material according to claim 1, wherein the resin composition contains a borate compound as a constituent element [D]. 16. An intermediate base material for a fiber-reinforced composite material, wherein a reinforcing fiber is impregnated with the epoxy resin composition according to any one of claims 1 to 15. 17. The intermediate substrate for a fiber-reinforced composite material according to claim 16, wherein the reinforcing fibers are at least one selected from carbon fibers and graphite fibers. 18. The intermediate substrate according to claim 16, wherein the reinforcing fiber satisfies at least one of the following characteristics. (1) The strand tensile strength is 4400 MPa or more. (2) The elongation is 1.8% or more. (3) The hook drop value is 12 cm or more. (4) It is a long fiber. (5) It is a woven cloth. 19. A fiber-reinforced composite material obtained by curing the intermediate substrate for a fiber-reinforced composite material according to any one of claims 16 to 18.