JP2022133796A - Curing agent composition for thermosetting resin, epoxy resin composition, and fiber-reinforced composite - Google Patents

Abstract

Kind Code: A1 A curing agent composition for a thermosetting resin is provided which is capable of producing an epoxy resin composition having a long pot life and fast curing properties.
A curing agent composition for a thermosetting resin comprising a curing agent A, a curing agent B and a curing agent C, wherein the curing agent A has substituents at two ortho-positions to an amino group. The substituent is selected from an alkyl group, an aromatic group and a halogen group, the curing agent B is an aromatic polyamine that is liquid at 25 ° C., and the curing agent C is an aromatic polyamine A curing agent composition for a thermosetting resin, wherein the aromatic polyamine is an aromatic polyamine having only one electron-donating group at the ortho position to the amino group or having no substituents at the ortho position. thing.
[Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a curing agent composition for thermosetting resins, and more particularly to a curing agent composition for thermosetting resins, which is capable of producing an epoxy resin composition having a long pot life and quick curing properties.

Fiber reinforced composite materials (hereinafter also referred to as "FRP") are lightweight, high strength, and high rigidity, so they are widely used in sports and leisure applications such as fishing rods and golf shafts, and industrial applications such as automobiles and aircraft. used in the field. As a method of molding a composite material using a thermosetting resin as a matrix resin, resin transfer molding ( RTM) method, and a method of molding a prepreg (intermediate base material) formed into a sheet by impregnating a fiber-reinforced base material with a resin in advance, and the like are known.

In recent years, in particular, the RTM molding method, which is a low-cost and highly productive manufacturing method that has few processes for manufacturing fiber-reinforced composite materials and does not require expensive equipment such as an autoclave, has attracted attention. ing. The composition of the matrix resin used in the RTM molding method mainly contains an epoxy resin and a curing agent, and optionally other additives. Aromatic polyamines are generally used as curing agents in order to obtain cured products and fiber-reinforced composite materials with high mechanical properties.

In the epoxy resin composition used in the RTM molding method, the curing agent and additives are dissolved in the epoxy resin that is the main ingredient in order to prevent the curing agent from being filtered out when the epoxy resin composition is impregnated into the reinforcing fiber base material. stored and used in many cases. Such an epoxy resin composition obtained by dissolving and mixing a curing agent and an additive into an epoxy resin as a main agent is called a one-liquid type epoxy resin composition.

In this one-liquid type epoxy resin composition, since the curing agent exists in a dissolved state in the epoxy resin, the reaction between the epoxy resin and the curing agent is relatively likely to occur, which shortens the shelf life of the epoxy resin composition. was there. For this reason, the one-liquid type epoxy resin composition had to be stored frozen.

In order to solve this problem, a two-liquid type epoxy resin composition, in which an epoxy resin and a curing agent are mixed immediately before use, has been studied. A two-component epoxy resin composition consists of a main liquid containing an epoxy resin as a main component and a curing agent liquid (curing agent composition) containing a curing agent as a main component, and these two liquids are mixed immediately before use. It is an epoxy resin composition obtained by

In a two-liquid type epoxy resin composition, since the base liquid and the curing agent liquid are mixed immediately before use, ease of mixing is important. The curing agent used for the one-component epoxy resin composition can be used as the curing agent for the two-component epoxy resin composition. Aromatic polyamine curing agents used in are usually solid and tend to be poorly mixed with the main liquid. Therefore, it is desirable that the curing agent composition is liquid.

As an epoxy resin composition using a liquid aromatic polyamine as a curing agent, those described in Patent Documents 2 and 3 are known. However, the resin cured products obtained from the epoxy resin compositions described in Patent Documents 2 and 3 do not have sufficient mechanical properties such as elastic modulus and fracture toughness.

In addition, in the RTM method, rapid curability is required to shorten the resin curing time in order to produce fiber-reinforced composite materials with high efficiency. Patent Document 4 proposes a fast-curing two-component epoxy resin composition using a compound having two or more aromatic rings having phenolic hydroxyl groups. However, when a compound having a phenolic hydroxyl group is added to the epoxy resin composition, the viscosity of the resin composition increases rapidly due to its high reactivity, and the pot life in RTM molding is extremely shortened. It becomes difficult to impregnate the inside of the material with a sufficient amount of resin. Therefore, a fiber-reinforced composite material produced using such an epoxy resin composition contains many defects such as voids. As a result, there is a problem that the compression performance and damage tolerance of the fiber-reinforced composite material structure are degraded.

JP 2014-148572 A JP 2015-193713 A WO2009/119467 Japanese Patent No. 6617559

Obtaining a resin cured product that has sufficient fast-curing properties to achieve a high level of productivity for fiber-reinforced composite materials, and also has the heat resistance and mechanical properties required for industrial applications such as automobiles and aircraft. There have been no two-part epoxy resin compositions capable of achieving this, nor a liquid curing agent composition capable of realizing such a composition.

An object of the present invention is to provide a curing agent composition for thermosetting resins that can produce an epoxy resin composition having a long pot life and fast curing properties. Furthermore, the present invention aims to provide a curing agent composition for thermosetting resins, which becomes a uniform liquid at a temperature of 200° C. or less by heating, and is capable of maintaining the uniform liquid state at room temperature for one week or longer. Make it an issue.
Another object of the present invention is to provide a cured epoxy resin composition and a fiber-reinforced composite material having high mechanical properties.

That is, the present invention provides a curing agent composition for thermosetting resins comprising a curing agent A, a curing agent B and a curing agent C, wherein the curing agent A has substituents at two ortho positions to an amino group. wherein the substituents are selected from alkyl groups, aromatic groups and halogen groups, curing agent B is an aromatic polyamine that is liquid at 25° C., curing agent C is an aromatic polyamine and the aromatic polyamine is an aromatic polyamine having only one electron-donating group at the ortho-position to the amino group or having no substituents at the ortho-position. composition.

According to the present invention, it is possible to provide a curing agent composition for thermosetting resins that can produce an epoxy resin composition having a long pot life and fast curing properties. Furthermore, it is possible to provide a curing agent composition for thermosetting resins, which becomes a uniform liquid at a temperature of 200° C. or less by heating, and can then maintain the uniform liquid state at room temperature for one week or longer. can.
The present invention can further provide a cured epoxy resin composition and a fiber-reinforced composite material with high mechanical properties.

The present invention will be described in detail below. A fiber reinforced composite material may be abbreviated as "FRP", and a carbon fiber reinforced composite material as "CFRP".

[Curing agent composition for thermosetting resin]
The curing agent composition for thermosetting resins of the present invention is a curing agent composition for thermosetting resins containing curing agent A, curing agent B and curing agent C. This curing agent composition for thermosetting resin becomes a uniform liquid by heating to a temperature of 80 to 200°C.

The curing agent composition for thermosetting resins of the present invention becomes a uniform liquid at a temperature of 80 to 200° C. After raising the liquid temperature to 200° C., lowering the temperature to 25° C., and allowing it to stand at 25° C. for 1 week, Preferably, it is a uniform liquid even after standing still for 2 weeks (3 weeks in total), and particularly preferably after standing still for 1 month.

After raising the liquid temperature to 200° C., lowering the temperature to 25° C. and allowing it to stand still at 25° C., if the period in which it is in a uniform liquid state is less than 1 week, the curing agent for thermosetting resin is substantially liquid. It is not preferable because it becomes difficult to handle as a composition and poor mixing with the main component liquid is likely to occur.

In the curing agent composition for thermosetting resins of the present invention, the total amount of curing agent A, curing agent B and curing agent C accounts for 70 to 100% by mass based on the total mass of the curing agent composition for thermosetting resins. .
The curing agent composition for thermosetting resins of the present invention may further contain other curing agents and other components as long as the above conditions are satisfied.

[Curing agent A]
Curing agent A is an aromatic polyamine having two substituents each ortho to the amino group, the substituents being selected from alkyl groups, aromatic groups and halogen groups. Also, curing agent A is solid at 25°C. By containing this curing agent A, when cured as a composition with an epoxy resin, it is possible to obtain an epoxy resin cured product having excellent mechanical properties such as heat resistance, elastic modulus, and fracture toughness.

A compound represented by the following chemical formula (1) can be used as the aromatic polyamine having substituents at two ortho-positions to the amino group, which is used as the curing agent A.

However, in the above chemical formula (1), R ₁ to R ₄ are each independently an aliphatic substituent, an aromatic substituent, an alkoxy group or a halogen atom, and at least one substituent has a carbon number Any of 1 to 6 aliphatic substituents, aromatic substituents and halogen atoms. X is -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -S-, -O-, -SO ₂ -, -CO-, -CONH-, -NHCO-, - It is either C(=O)- and -OC(=O)-.

In chemical formula (1), aliphatic substituents having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group and n-pentyl group. , neopentyl group, n-hexyl group, and cyclohexyl group. A phenyl group and a naphthyl group are illustrated as an aromatic substituent.

The aromatic polyamine of curing agent A is preferably an aromatic diamine, of which 4,4'-diaminodiphenylmethane derivatives are particularly preferred.
Specific examples of aromatic polyamines include compounds represented by the following chemical formulas (2) to (5). These may be used alone or in combination.

[Curing agent B]
Hardener B is an aromatic polyamine that is liquid at 25°C. By containing this aromatic polyamine, it is possible to obtain a curing agent composition for thermosetting resins that can maintain a liquid state at room temperature.

As the aromatic polyamine for the curing agent B, a phenylenediamine derivative or a 4,4'-diaminodiphenylmethane derivative is preferably used. Examples of this aromatic polyamine include compounds represented by the following chemical formula (6) or (7).

However, in chemical formula (6), R ₅ to R ₈ are each independently a hydrogen atom, an aliphatic substituent, an alkoxy group or a thioalkoxy group, and at least one substituent has 1 to 6 carbon atoms. is either an aliphatic substituent of or a thioalkoxy group.

However, in chemical formula (7), R ₉ to R ₁₀ are each independently an aliphatic substituent, a methoxy group, an alkoxy group or a thioalkoxy group.

As an aromatic polyamine used as curing agent B. Specifically, compounds represented by the following chemical formulas (8) to (12) can be exemplified. These may be used alone or in combination.

In the curing agent composition for thermosetting resins of the present invention, the mass ratio of curing agent A to curing agent B is preferably 1:99 to 99:1, more preferably 20:80 to 80:20, particularly preferably 40:60 to 70:30. If the proportion of the curing agent A is less than this, mechanical properties such as heat resistance, elastic modulus and fracture toughness of the resin cured product obtained tend to be insufficient, which is not preferable. On the other hand, if the ratio of the curing agent A is higher than this, it becomes difficult for the obtained curing agent composition for thermosetting resins to maintain a liquid state at room temperature, which is undesirable.

[Curing agent C]
Curing agent C is an aromatic polyamine having only one electron donating group ortho to the amino group or no substituents ortho to the amino group. The electron-donating group of the aromatic polyamine of curing agent C is preferably methyl, ethyl, propyl, isopropyl, methoxy or ethoxy. By including this curing agent C, the curing reaction of the resulting epoxy resin composition is accelerated, and rapid curing can be imparted to the epoxy resin composition.

As curing agent C, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis(4-aminophenoxy) benzene, 1,3-bis(3-aminophenoxy)benzene, 4,4'-thiodianiline, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 1,1-bis(4-aminophenyl)cyclohexane, 3,3'-diaminobenzophenone, m-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,4,6-trimethyl-1,3-phenylenediamine, 4,4'-diaminodiphenyl sulfone , 3,3′-diaminodiphenylsulfone, 3,4′-diaminodiphenylsulfone, o-dianisidine, and 3,3′,5,5′-tetramethylbenzidine. Among them, 3,4′-diaminodiphenyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3- aminophenoxy)benzene, 2,6-diaminotoluene, m-phenylenediamine, 3,4′-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene, 2,6-diaminotoluene, m-phenylenediamine is preferred.

The melting point of the curing agent C is preferably 200° C. or lower, more preferably 150° C. or lower, particularly preferably 120° C. or lower. If the melting point exceeds 200° C., it becomes difficult to obtain a liquid composition when the curing agent C is mixed with the curing agents A and B, and the obtained curing agent composition for thermosetting resins is cooled at room temperature. It is not preferable because it tends to be difficult to maintain the liquid state. Also, curing agent A is solid at 25°C.

In the curing agent composition for thermosetting resins of the present invention, the curing agent C is preferably 1 to 43 parts by mass, more preferably 3 to 30 parts by mass with respect to a total of 100 parts by mass of the curing agent A and the curing agent B. parts, particularly preferably 5 to 20 parts by weight. If the content is less than 1 part by mass, it becomes difficult to impart rapid curability to the resulting epoxy resin composition, which is not preferred. On the other hand, when it exceeds 43 parts by mass, the reactivity of the obtained epoxy resin composition becomes excessively high, and the pot life in RTM molding becomes extremely short, which is not preferable. In this case, it becomes difficult to impregnate the inside of the reinforcing fiber base material with a sufficient amount of resin, and the fiber-reinforced composite material produced using such an epoxy resin composition contains many defects such as voids. As a result, the compressive performance and damage tolerance of the fiber reinforced composite structure are reduced.

[Other ingredients]
The curing agent composition for thermosetting resins of the present invention may further contain other components, such as conductive particles, flame retardants, inorganic fillers, and internal release agents. .

Conductive particles include conductive polymer particles such as polyacetylene particles, polyaniline particles, polypyrrole particles, polythiophene particles, polyisothianaphthene particles and polyethylenedioxythiophene particles; carbon particles; carbon fiber particles; metal particles; Particles in which a core material composed of is coated with a conductive substance can be exemplified.

As a flame retardant, a phosphorus-based flame retardant can be exemplified. The phosphorus-based flame retardant may contain a phosphorus atom in the molecule, and examples thereof include organic phosphorus compounds such as phosphoric acid esters, condensed phosphoric acid esters, phosphazene compounds and polyphosphates, and red phosphorus.

Examples of inorganic fillers include aluminum borate, calcium carbonate, silicon carbonate, silicon nitride, potassium titanate, basic magnesium sulfate, zinc oxide, graphite, calcium sulfate, magnesium borate, magnesium oxide, and silicate minerals. can do.
In particular, it is preferable to use silicate minerals. Commercially available silicate minerals include THIXOTROPIC AGENT DT 5039 (manufactured by Huntsman Japan KK).

Examples of internal mold release agents include metallic soaps, vegetable waxes such as polyethylene wax and carnauba wax, fatty acid ester mold release agents, silicone oils, animal waxes, and fluorine-based nonionic surfactants. Commercially available internal release agents include MOLD WIZ (registered trademark), INT1846 (AXEL PLASTICS RESEARCH
LABORATORIES INC. ), Licowax S, Licowax P, Licowax OP, Licowax PE190, Licowax PED (manufactured by Clariant Japan), and stearyl stearate (SL-900A; manufactured by Riken Vitamin Co., Ltd.).

[Method for producing curing agent composition for thermosetting resin]
The curing agent composition for thermosetting resins of the present invention can be produced by mixing curing agent A, curing agent B, curing agent C, and, if necessary, other components. The order of mixing does not matter.

The temperature of the composition during mixing is preferably 50-200°C, more preferably 50-150°C, and particularly preferably 80-120°C. If the temperature exceeds 200°C, the added components may be thermally decomposed, which is not preferable. On the other hand, when the temperature is lower than 50°C, the solid curing agents A and C do not melt and are difficult to melt into the curing agent B, making it difficult to obtain a liquid curing agent composition for thermosetting resins. It is not preferable.

Examples of equipment used for mixing the curing agent include roll mills, planetary mixers, kneaders, extruders, Banbury mixers, mixing vessels equipped with stirring blades, and horizontal mixing tanks. Mixing may be performed in air or under an inert gas atmosphere.

When mixing in air, it is preferable to perform the mixing in an atmosphere in which the temperature and humidity are controlled. In this case, it is preferable to mix at a constant temperature of, for example, 30° C. or less, or in a low-humidity atmosphere with a relative humidity of 50% RH or less.

[Epoxy resin main agent]
The epoxy resin base agent comprises an epoxy resin. The epoxy resin main agent may contain other optional components in addition to these. The content of the epoxy resin in the epoxy resin main agent is 30 to 100% by weight, preferably 50 to 100% by weight, based on the total weight of the epoxy resin main agent.

〔Epoxy resin〕
Epoxy resins that can be used in the epoxy resin composition are not particularly limited, but tetraglycidyl-4,4'-diaminodiphenylmethane, tetraglycidyl-4,4'-diaminodiphenylsulfone, tetraglycidyl-3,3'-diaminodiphenylsulfone. , tetraglycidyl-4,4'-diaminodiphenyl ether, tetraglycidyl-3,4'-diaminodiphenyl ether, tetrafunctional glycidylamine type epoxy resins, triglycidyl-m-aminophenol, triglycidyl-p-aminophenol, isocyanur trifunctional epoxy resins such as triglycidyl acid, diglycidylaniline and its derivatives diglycidyl-o-toluidine, diglycidyl-m-toluidine, diglycidyl-p-toluidine, diglycidyl-xylidine, diglycidyl-mesidine, diglycidyl-anisidine, diglycidyl -Bifunctional epoxies such as phenoxyaniline, or diglycidyl-naphthylamine and its derivatives, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, resorcinol diglycidyl ether, 1,6-naphthalene diol diglycidyl ether, etc. Resin is exemplified. These epoxy resins may be used alone, or a plurality of epoxy resins may be mixed and used.

The epoxy resin may be synthesized as required. It may be synthesized by any method, but for example, after reacting an aromatic diamine, aminophenol, or diphenol as a raw material with an epihalohydrin such as epichlorohydrin to obtain a halohydrin body, an alkaline compound is then added. obtained by a cyclization reaction using

Epihalohydrin includes, for example, epichlorohydrin, epibromohydrin, epifluorohydrin, and the like. Among these, epichlorohydrin and epibromohydrin are particularly preferred from the viewpoint of reactivity and handleability.

The molar ratio of raw materials such as aromatic diamine, aminophenol or diphenol to epihalohydrin is preferably 1:1 to 1:30, more preferably 1:3 to 1:20. Solvents used for the reaction include alcohol solvents such as ethanol and n-butanol, ketone solvents such as methyl isobutyl ketone and methyl ethyl ketone, aprotic polar solvents such as acetonitrile and N,N-dimethylformamide, and toluene and xylene. Aromatic hydrocarbon solvents are exemplified. The amount of solvent to be used is preferably 1 to 10 times the weight of the aromatic diamine.

The reaction time is preferably 0.1 to 180 hours, more preferably 0.5 to 24 hours. The reaction temperature is preferably 20-100°C, more preferably 40-80°C.

Examples of alkaline compounds used in the cyclization reaction include sodium hydroxide and potassium hydroxide. The alkaline compound may be added as a solid or as an aqueous solution.

A phase transfer catalyst may be used during the cyclization reaction. Phase transfer catalysts include quaternary ammonium salts such as tetramethylammonium chloride, tetraethylammonium bromide, benzyltriethylammonium chloride, and tetrabutylammonium hydrogen sulfate; phosphonium compounds such as tributylhexadecylphosphonium bromide and tributyldodecylphosphonium bromide; Examples include crown ethers such as 18-crown-6-ether.

[Optional component]
The epoxy resin main agent may contain a thermoplastic resin in addition to the above epoxy resins. The thermoplastic resin improves the fracture toughness and impact resistance of the resulting fiber-reinforced composite material. Such a thermoplastic resin may be dissolved in the thermosetting resin curing agent composition during the production process of the thermosetting resin curing agent composition.

Specific examples of thermoplastic resins include polyethersulfone, polysulfone, polyetherimide, polycarbonate and the like. These may be used alone or in combination of two or more. The thermoplastic resin contained in the epoxy resin composition is particularly preferably polyethersulfone or polysulfone having a weight average molecular weight (Mw) measured by gel permeation chromatography in the range of 8,000 to 100,000. If the weight-average molecular weight (Mw) is 8000 or more, the resulting FRP will have sufficient impact resistance, and if it is 100000 or less, an epoxy resin composition will be obtained which exhibits good handleability without markedly increasing viscosity. be done. The epoxy resin-soluble thermoplastic resin preferably has a uniform molecular weight distribution. In particular, the polydispersity (Mw/Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably in the range of 1 to 10, more preferably in the range of 1.1 to 5. more preferred.

The thermoplastic resin preferably has a reactive group reactive with the epoxy resin or a functional group forming a hydrogen bond. Such thermoplastic resins can improve the dissolution stability during the curing process of epoxy resins. In addition, fracture toughness, chemical resistance, heat resistance, and resistance to moist heat can be imparted to the fiber-reinforced composite material obtained after curing.

A hydroxyl group, a carboxylic acid group, an imino group, an amino group and the like are preferable as the reactive group having reactivity with the epoxy resin. The use of hydroxyl-terminated polyethersulfone is more preferable because the resulting fiber-reinforced composite material has particularly excellent impact resistance, fracture toughness and solvent resistance.

The content of the thermoplastic resin contained in the thermosetting resin curing agent composition is appropriately adjusted according to the viscosity. From the viewpoint of impregnation into the fiber-reinforced base material, the amount is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, with respect to 100 parts by mass of the curing agent composition for thermosetting resins. When the content is 0.1 part by mass or more, the resulting fiber-reinforced composite material exhibits sufficient fracture toughness and impact resistance. When the content of the thermoplastic resin is 10 parts by mass or less, the viscosity of the epoxy resin composition does not significantly increase, the impregnation of the fiber-reinforced base material is facilitated, and the properties of the obtained fiber-reinforced composite material are improved. .

The thermoplastic resin preferably contains a reactive aromatic oligomer having amine end groups (hereinafter also simply referred to as "aromatic oligomer").

The epoxy resin composition has a high molecular weight due to a curing reaction between the epoxy resin and the curing agent during heat curing. The expansion of the two-phase region due to the increase in the molecular weight causes the aromatic oligomer dissolved in the epoxy resin composition to undergo reaction-induced phase separation. Due to this phase separation, a two-phase resin structure in which the cured epoxy resin and the aromatic oligomer are co-continuous is formed in the matrix resin. Also, since aromatic oligomers have amine end groups, they also react with epoxy resins. Since each phase in this co-continuous two-phase structure is strongly bonded to each other, solvent resistance is also improved.

This co-continuous structure absorbs external impact on the fiber-reinforced composite material and suppresses crack propagation. As a result, fiber reinforced composites made with epoxy resin compositions containing reactive aromatic oligomers with amine end groups have high impact resistance and fracture toughness.

As the aromatic oligomer, known polysulfones having amine end groups and polyether sulfones having amine end groups can be used. Preferably, the amine end groups are primary amine (--NH ₂ ) end groups.

The aromatic oligomer blended in the epoxy resin composition preferably has a weight average molecular weight of 8,000 to 40,000 as measured by gel permeation chromatography. When the weight average molecular weight is 8000 or more, the effect of improving the toughness of the matrix resin is high. Moreover, when the weight average molecular weight is 40,000 or less, the viscosity of the resin composition does not become too high, and processing advantages such as the impregnation of the reinforcing fiber base material with the resin composition being facilitated can be obtained.

As the aromatic oligomer, commercially available products such as "Virantage DAMS VW-30500 RP (registered trademark)" (manufactured by Solvay Specialty Polymers) can be preferably used.

The form of the thermoplastic resin before being blended into the thermosetting resin curing agent composition is not particularly limited, but it is preferably particulate. The particulate thermoplastic resin can be uniformly blended and dissolved in the resin composition.

A particulate rubber component may be blended into the epoxy resin base. In the present invention, the term "particulate" means that the particles are not dissolved but dispersed in the epoxy resin main agent, and even in the resin cured product using the epoxy resin main agent, they are dispersed to form island components.

The particulate rubber component improves the fracture toughness and impact resistance of cured resins and fiber composite materials.
Particulate rubber components include silicone rubber, butadiene rubber, styrene-butadiene rubber, and methyl methacrylate-butadiene-styrene rubber.

The average particle size of the particulate rubber component is preferably 1 µm or less, more preferably 0.5 µm or less, and even more preferably 0.3 µm or less. Although the lower limit of the average particle size is not particularly limited, it is preferably 0.03 μm or more, more preferably 0.05 μm or more, and even more preferably 0.08 μm or more. When the average particle size exceeds 1 μm, the particulate rubber component is filtered out on the surface of the reinforcing fiber base material in the step of impregnating the reinforcing fiber base material, making it difficult to impregnate the inside of the reinforcing fiber bundle. As a result, poor resin impregnation may occur, and the physical properties of the resulting fiber-reinforced composite material may deteriorate.

The content of the particulate rubber component in the epoxy resin composition produced using the thermosetting resin curing agent composition of the present invention and the epoxy resin base resin is from 0.1 to 0.1 in the total amount of the epoxy resin composition. It is preferably 50% by mass, more preferably 0.5 to 20% by mass, even more preferably 1 to 15% by mass. If it is less than 0.1% by mass, the fracture toughness and impact resistance of the cured resin and fiber composite material are not sufficiently improved.

The particulate rubber component can also be used as a masterbatch dispersed in an epoxy resin at high concentration. In this case, it becomes easy to highly disperse the rubber-like component in the epoxy resin composition.

Commercially available particulate rubber components include MX-153 (a bisphenol A type epoxy resin in which 33% by mass of butadiene rubber is monodispersed, manufactured by Kaneka Corporation), MX-257 (bisphenol A type epoxy 37% by mass of butadiene rubber is dispersed in a resin, manufactured by Kaneka Corporation), MX-154 (bisphenol A type epoxy resin, 40% by mass of butadiene rubber is dispersed in a single dispersion, stock Kaneka Co., Ltd.), MX-960 (bisphenol A type epoxy resin with 25% by mass of silicone rubber dispersed in a single dispersion, manufactured by Kaneka Corporation), MX-136 (bisphenol F type epoxy resin with 25% Monodispersed mass% butadiene rubber, manufactured by Kaneka Co., Ltd.), MX-965 (bisphenol F type epoxy resin, 25% by mass of silicone rubber monodispersed, manufactured by Kaneka Co., Ltd. ), MX-217 (25% by mass of butadiene rubber dispersed in a phenol novolak type epoxy resin, manufactured by Kaneka Corporation), MX-227M75 (bisphenol A novolac type epoxy resin, 25% by mass of Styrene-butadiene rubber monodispersed, manufactured by Kaneka Corporation), MX-334M75 (brominated epoxy resin, 25% by mass of styrene-butadiene rubber monodispersed, manufactured by Kaneka Corporation), MX-416 (tetrafunctional glycidylamine epoxy resin, 25% by mass of butadiene rubber monodispersed, manufactured by Kaneka Corporation), MX-451 (trifunctional glycidylamine epoxy resin, 25% by mass styrene-butadiene rubber, manufactured by Kaneka Corporation).

As other additives, conductive particles, flame retardants, inorganic fillers, and internal mold release agents may be added to the epoxy resin main agent.

Conductive particles include conductive polymer particles such as polyacetylene particles, polyaniline particles, polypyrrole particles, polythiophene particles, polyisothianaphthene particles and polyethylenedioxythiophene particles; carbon particles; carbon fiber particles; Particles in which a core material made of a material is coated with a conductive substance are exemplified.

Examples of flame retardants include phosphorus-based flame retardants. The phosphorus-based flame retardant is not particularly limited as long as it contains a phosphorus atom in the molecule. be done.

Examples of inorganic filler materials include aluminum borate, calcium carbonate, silicon carbonate, silicon nitride, potassium titanate, basic magnesium sulfate, zinc oxide, graphite, calcium sulfate, magnesium borate, magnesium oxide, and silicates. minerals. In particular, it is preferable to use silicate minerals. Commercially available silicate minerals include THIXOTROPIC AGENT DT 5039 (manufactured by Huntsman Japan KK).

Examples of internal release agents include metal soaps, vegetable waxes such as polyethylene wax and carnauba wax, fatty acid ester release agents, silicone oils, animal waxes, and fluorine-based nonionic surfactants. The content of these internal release agents is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 2 parts by mass, per 100 parts by mass of the epoxy resin. Within this range, the release effect from the mold is favorably exhibited.

Commercially available internal release agents include "MOLD WIZ (registered trademark)" INT1846 (manufactured by AXEL PLASTICS RESEARCH LABORATORIES INC.), Licowax S, Licowax P, Licowax OP, Licowax PE190, Licowax PED (manufactured by Clariant Japan), Stearyl stearate (SL-900A; manufactured by Riken Vitamin Co., Ltd.).

[Method for producing epoxy resin main agent]
The epoxy resin main agent can be produced by mixing an epoxy resin and, if necessary, other optional components. The order of these mixtures does not matter.
The state of the epoxy resin composition may be a one-liquid state in which each component is uniformly mixed, or a slurry state in which some components are dispersed as solids.

The method for producing the epoxy resin main agent is not particularly limited, and any conventionally known method may be used. As the mixing temperature, a range of 40 to 200° C. can be exemplified. If the temperature exceeds 200°C, the self-polymerization reaction of the epoxy resin partially progresses, resulting in a decrease in the impregnation of the reinforcing fiber base material, and the physical properties of the cured resin produced using the obtained epoxy resin base material decrease. may do so. If the temperature is less than 40°C, the viscosity of the epoxy resin base agent is high, and mixing may be substantially difficult. It is preferably in the range of 50 to 100°C, more preferably in the range of 50 to 90°C.

A conventionally known machine can be used as the mixing machine. Specific examples include roll mills, planetary mixers, kneaders, extruders, Banbury mixers, mixing vessels equipped with stirring blades, and horizontal mixing tanks. Mixing of each component can be performed in air or under an inert gas atmosphere. When mixing is performed in air, an atmosphere in which temperature and humidity are controlled is preferable. Although not particularly limited, for example, it is preferable to mix at a temperature controlled at a constant temperature of 30° C. or less or in a low-humidity atmosphere with a relative humidity of 50% RH or less.

[Epoxy resin composition]
The epoxy resin composition comprises the thermosetting resin curing agent composition of the present invention and an epoxy resin main agent.

The epoxy resin composition preferably has a viscosity at 100° C. of 50 mPa·s or less, more preferably 30 mPa·s, and even more preferably 20 mPa·s. If the viscosity at 100° C. exceeds 50 mPa·s, impregnation of the reinforcing fiber base material with the epoxy resin composition becomes difficult. As a result, voids and the like are likely to be formed in the resulting fiber-reinforced composite material, causing deterioration in physical properties. Note that the relationship between the viscosity and the impregnability depends on the structure of the reinforcing fiber base material, and even if the viscosity is outside the above range, the impregnation of the reinforcing fiber base material may be good in some cases.

In addition, the pot life of the epoxy resin composition varies depending on the molding conditions of the composite material. When the material is impregnated, the usable time until the viscosity exceeds 50 mPa s when held at 100 ° C. is preferably 60 minutes or more, more preferably 180 minutes or more, and 300 minutes. minutes or more is more preferable.

The total amount of the curing agent contained in the epoxy resin composition is an amount suitable for curing all the epoxy resins contained in the epoxy resin composition, and may be appropriately adjusted depending on the type of epoxy resin and curing agent used. adjusted. Specifically, the ratio of the total number of epoxy groups of the epoxy resin in the epoxy resin composition to the number of active hydrogens contained in the thermosetting resin curing agent composition is preferably 0.7 to 1.3, and further It is preferably 0.8 to 1.2, particularly preferably 0.9 to 1.1. If the ratio of the number of active hydrogens is less than 0.7 or exceeds 1.3, the molar balance between the epoxy groups and the active hydrogens will be disturbed, and the resulting cured resin will have insufficient cross-linking density, resulting in poor heat resistance and elasticity. It is not preferable because the mechanical properties such as modulus and fracture toughness are lowered.

According to the present invention, it is possible to obtain an epoxy resin composition in which the cured product obtained by curing at 180° C. for 30 minutes has a DSC curing degree α represented by the following formula of 98% or more.
α = (ΔH uncured - ΔH cured product) / ΔH uncured × 100
(However, ΔH is the amount of heat generated due to the curing reaction confirmed when DSC measurement is performed at a temperature increase rate of 20° C./minute, and ΔH uncured is the ΔH of the uncured epoxy resin composition, and ΔH The cured product is ΔH of the resin cured product.)

That is, the epoxy resin composition of the present invention is an epoxy resin composition in which a cured product obtained by curing at 180° C. for 30 minutes has a DSC curing degree α represented by the above formula of 98% or more. When the DSC curing degree α is 98% or more, excellent heat resistance and mechanical properties can be obtained, and changes in properties over time can be suppressed.

[Epoxy resin cured product]
The present invention is also an epoxy resin cured product obtained by curing the above epoxy resin composition.

The cured resin has a glass transition temperature of preferably 150° C. or higher, more preferably 180° C. or higher, particularly preferably 200° C. or higher. If it is less than 150°C, the heat resistance is insufficient for industrial use, which is not preferable.
The epoxy resin cured product preferably has a glass transition temperature of 120° C. or higher, more preferably 140° C. or higher when water is absorbed. If it is less than 120°C, the heat resistance will be insufficient for industrial use, which is not preferable.

The cured resin preferably has a flexural modulus of 3.0 GPa or higher, more preferably 3.3 GPa or higher, particularly preferably 3.5 GPa or higher, as measured by JIS K7171. If it is less than 3.0 GPa, the properties of the fiber-reinforced composite material obtained using the epoxy resin composition tend to deteriorate, which is not preferable.

[Fiber-reinforced composite material]
The present invention is also a fiber-reinforced composite material comprising the cured epoxy resin and a fiber-reinforced base material. This fiber-reinforced composite material can be obtained by compounding and curing a fiber-reinforced base material and the epoxy resin composition of the present invention. A carbon fiber reinforced substrate is preferably used as the fiber reinforced substrate. Curing can be performed by heating.

As a method for compounding the fiber-reinforced base material and the epoxy resin composition, the fiber-reinforced base material and the epoxy resin composition may be compounded in advance, for example, a resin transfer molding method (RTM method) or a hand lay-up method. , a filament winding method, and a pultrusion method.

Examples of methods for producing a fiber-reinforced composite material using the epoxy resin composition of the present invention include RTM, autoclave molding, and press molding. The epoxy resin composition of the present invention is particularly suitable for the RTM method. Here, the RTM method is a method for obtaining a fiber-reinforced composite material by impregnating a fiber-reinforced base material placed in a mold with a liquid epoxy resin composition and curing the composition. The RTM method is a preferable molding method from the viewpoint of efficiently obtaining a complex-shaped fiber-reinforced composite material.

In the present invention, as the mold used in the RTM method, a closed mold made of a rigid material may be used, or an open mold made of a rigid material and a flexible film (bag) may be used. In the latter case, the fiber reinforced substrate can be placed between an open mold of rigid material and the flexible film. Examples of rigid materials that can be used include metals such as steel and aluminum, fiber reinforced plastics (FRP), wood, and gypsum. Examples of flexible film materials that can be used include polyamide, polyimide, polyester, fluororesin, and silicone resin.

When a rigid material closed mold is used in the RTM method, the mold is clamped under pressure and the epoxy resin composition is injected under pressure. At this time, a suction port may be provided separately from the injection port and connected to a vacuum pump for suction. When suction is performed, the epoxy resin composition can be injected only at atmospheric pressure without using special pressurizing means. In this method, a large-sized member can be manufactured by providing a plurality of suction ports, and it can be used preferably.

In the RTM method, when an open mold made of a rigid material and a flexible film are used, suction may be performed and the epoxy resin may be injected only under atmospheric pressure without using special pressurizing means. It is effective to use a resin diffusion medium to achieve good impregnation by injection at atmospheric pressure only. Additionally, a gel coat may be applied to the surface of the rigid material prior to installation of the fiber reinforced substrate.

In the RTM method, the fiber-reinforced base material is impregnated with the epoxy resin composition and then heat-cured. The mold temperature during heat curing is usually selected to be higher than the mold temperature during injection of the epoxy resin composition. The mold temperature during heat curing is, for example, 80 to 200.degree. The heat curing time is, for example, 1 minute to 20 hours. After heat curing is completed, the fiber-reinforced composite material is taken out by demolding. The resulting fiber-reinforced composite material may then be heated at a higher temperature for post-curing. The post-curing temperature is, for example, 150 to 200° C., and the time is, for example, 1 minute to 4 hours.

The impregnation pressure for impregnating the fiber-reinforced base material with the epoxy resin composition by the RTM method may be appropriately determined in consideration of the viscosity and resin flow of the resin composition. A specific impregnation pressure is preferably 0.001 to 10 MPa, more preferably 0.01 to 1 MPa. When obtaining a fiber-reinforced composite material using the RTM method, the epoxy resin composition preferably has a viscosity at 100° C. of 50 mPa s or less, more preferably 30 mPa s, and 20 mPa s. is more preferred. If the viscosity at 100° C. exceeds 50 mPa·s, impregnation of the reinforcing fiber base material with the epoxy resin composition becomes difficult.

In the RTM method, the epoxy resin composition is preferably produced by mixing the thermosetting resin curing agent composition of the present invention with the epoxy resin immediately before impregnation. Although the curing agent composition for thermosetting resins of the present invention has high reactivity with epoxy resins, the viscosity of the epoxy resin composition increases by being mixed to form an epoxy resin composition immediately before impregnation. A sufficient amount of the epoxy resin composition can be impregnated inside the reinforcing fiber base material in advance. Therefore, the produced fiber-reinforced composite material does not contain defects such as voids, and is excellent in compression performance and damage tolerance.

Thus, according to the present invention, a method for producing a fiber-reinforced composite material is provided. That is, a method for producing a fiber-reinforced composite material comprising a step of impregnating a fiber-reinforced base material with the epoxy resin composition of the present invention to obtain an impregnated base material, and a step of curing the impregnated base material obtained in the step. be.

In this production method, the step of impregnating a fiber-reinforced base material with the epoxy resin composition of the present invention to form an impregnated base material includes impregnating the fiber-reinforced base material placed in a mold with the epoxy resin composition of the present invention. It is preferable that the step of curing the impregnated base material obtained in the step is a step of heat-curing the impregnated base material.
A step of preparing the epoxy resin composition of the present invention is preferably included immediately before the step of impregnating a fiber-reinforced base material with the epoxy resin composition of the present invention to form an impregnated base material.

EXAMPLES The present invention will be described in more detail below with reference to examples. Components and evaluation methods used in Examples and Comparative Examples are described below.

1. Raw materials for epoxy resin composition (1) Curing agent (1-1) Curing agent A
· 4,4'-diamino-3,3'-diisopropyl-5,5'-dimethyldiphenylmethane (Lonzacure M-MIPA (product name) manufactured by Lonza, hereinafter abbreviated as "M-MIPA", melting point 70 ° C., 25 solid at °C)
· 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane (MED-J (product name) manufactured by Kumiai Chemical Co., Ltd., hereinafter abbreviated as "MED-J", melting point 76 ° C., 25 solid at °C)

(1-2) Curing agent B
・ Diethyltoluenediamine (Heart Cure 10 (product name) manufactured by Kumiai Chemical Co., Ltd., hereinafter abbreviated as “DETDA”, liquid at 25 ° C.)
・ Dimethylthiotoluene diamine (Kumiai Chemical Co., Ltd. Heart Cure 30 (product name), hereinafter abbreviated as “DMTDA”, liquid at 25 ° C.)

(1-3) Curing agent C
3,4'-diaminodiphenyl ether (manufactured by Teijin Limited, hereinafter abbreviated as "3,4'-DAPE", melting point 80°C, solid at 25°C)
· 2,2-bis[4-(4-aminophenoxy)phenyl]propane (manufactured by Tokyo Chemical Industry Co., Ltd., hereinafter abbreviated as “BAPP”, melting point 129 ° C., solid at 25 ° C.)
・ 1,3-bis(4-aminophenoxy)benzene (manufactured by Tokyo Chemical Industry Co., Ltd., hereinafter abbreviated as “TPE-R”, melting point 116 ° C., solid at 25 ° C.)
・ 1,3-bis(3-aminophenoxy)benzene (manufactured by Tokyo Chemical Industry Co., Ltd., hereinafter abbreviated as “APB”, melting point 108 ° C., solid at 25 ° C.)
2,6-diaminotoluene (manufactured by Tokyo Chemical Industry Co., Ltd., hereinafter abbreviated as “DAT”, melting point 106 ° C., solid at 25 ° C.)
· m-phenylenediamine (manufactured by Fujifilm Wako Pure Chemical Industries, hereinafter abbreviated as “MPD”, melting point 65 ° C., solid at 25 ° C.)

(2) Epoxy resin N,N-diglycidyl-o-toluidine (GOT (product name) manufactured by Nippon Kayaku Co., Ltd., hereinafter abbreviated as "GOT")
・N,N-diglycidylaniline (GAN (product name) manufactured by Nippon Kayaku Co., Ltd., hereinafter abbreviated as “GAN”)
- Tetraglycidyl-3,4'-diaminodiphenyl ether This was synthesized by the method of Synthesis Example 1 below. Hereinafter, it is abbreviated as "3,4'-TGDDE".

[Synthesis Example 1] Synthesis of 3,4'-TGDDE A four-necked flask equipped with a thermometer, a dropping funnel, a cooling tube and a stirrer was charged with 1110.2 g (12.0 mol) of epichlorohydrin and purged with nitrogen. The temperature was raised to 70° C. while continuing, and 200.2 g (1.0 mol) of 3,4′-diaminodiphenyl ether dissolved in 1000 g of ethanol was added dropwise over 4 hours. After further stirring for 6 hours, the addition reaction was completed to give N,N,N',N'-tetrakis(2-hydroxy-3-chloropropyl)-3,4'-diaminodiphenyl ether. Subsequently, after the temperature in the flask was lowered to 25° C., 500.0 g (6.0 mol) of 48% NaOH aqueous solution was added dropwise over 2 hours, and the mixture was further stirred for 1 hour. After completion of the cyclization reaction, ethanol was distilled off, extraction was performed with 400 g of toluene, and washing was performed twice with 5% saline. When toluene and epichlorohydrin were removed from the organic layer under reduced pressure, 361.7 g (yield 85.2%) of a brown viscous liquid containing 3,4'-TGDDE as a main component was obtained.

(3) Particulate rubber component MX-416 (Kaneka Corporation MX-416 (product name), a master obtained by dispersing the particulate rubber component in a glycidylamine-type tetrafunctional epoxy resin to a concentration of 25% by mass. batch)

2. Evaluation Method (1) Properties of Curing Agent Composition (1-1) Preparation of Curing Agent Composition Weigh the curing agent in the ratio shown in the table, and use a stirrer at an appropriate temperature of 90 to 110° C. for 60 minutes. Mixed to prepare a hardener composition.

(1-2) Confirmation of Retention of Curing Agent Composition in Liquid State The curing agent composition prepared in (1-1) was stored at room temperature for 1 week, and precipitation of solid components was visually confirmed. A sample with no precipitation was rated as “◯”, and a sample with deposition was rated as “x”.

(2) Properties of Resin Composition (2-1) Preparation of Epoxy Resin Composition The curing agent composition prepared in (1-1), the epoxy resin, and the particulate rubber component were weighed in proportions shown in the table, The mixture was mixed at 80° C. for 60 minutes using a stirrer to prepare an epoxy resin composition. In addition, in the composition shown in the table, the epoxy group of the epoxy resin and the active hydrogen of the curing agent are equivalent.

(2-2) Initial Viscosity and Pot Life Viscosity was measured at 100° C. using a Brookfield viscometer TVB-15M manufactured by Toki Sangyo Co., Ltd. The minimum measured value immediately after the start of measurement was taken as the initial viscosity, and the time when the viscosity reached 50 mPa·s was taken as the pot life.

(3) Properties of cured resin product (3-1) Production of cured resin product After defoaming the epoxy resin composition prepared in (2-1) in a vacuum, it was reduced to a thickness of 4 mm with a 4 mm thick silicon resin spacer. It was injected into a stainless steel mold set to It was cured at a temperature of 180° C. for 30 minutes to obtain a resin cured product having a thickness of 4 mm.

(3-2) Curing degree Curing degree α was calculated using the following formula.
α = (ΔH uncured - ΔH cured product) / ΔH uncured × 100
(However, ΔH is the amount of heat generated due to the curing reaction confirmed when DSC measurement is performed at a heating rate of 20° C./minute, and ΔH is the uncured epoxy resin composition prepared in (2-1). ΔH, and the ΔH cured product is the ΔH of the resin cured product prepared in (3-1).)

(3-3) wet-Tg
The glass transition temperature was measured according to the SACMA 18R-94 method.
The dimensions of the resin test piece were 50 mm x 6 mm x 2 mm. Using a pressure cooker (HASTEST PC-422R8, manufactured by Espec Co., Ltd.), a resin test piece prepared under water vapor saturation conditions at 121° C. for 24 hours was subjected to water absorption treatment. Using a dynamic viscoelasticity measuring device Rheogel-E400 manufactured by UBM, the measurement frequency is 1 Hz, the temperature increase rate is 5 ° C./min, and the strain is 0.0167%. The storage elastic modulus E' of the resin test piece subjected to water absorption treatment was measured. Log E′ was plotted against temperature, and the temperature obtained from the intersection of the approximate straight line of the flat region of log E′ and the approximate straight line of the transition region of E′ was recorded as the glass transition temperature (Tg).

(3-4) Resin flexural modulus A test was carried out according to JIS K7171 method. At that time, the resin test piece was prepared with dimensions of 80 mm×10 mm×4 mm (thickness h). A bending test was performed at a distance L between fulcrums of 16×h (thickness) and a test speed of 2 m/min to measure bending strength and bending elastic modulus.

(3-5) K1c
The test was performed according to ASTM D5045 method. At that time, the dimensions of the resin test piece were prepared to be 50 mm×8 mm (width W)×4 mm. The crack length a was adjusted so that 0.45≦a/W≦0.55. For the crack length a, the fracture surface after the fracture test was observed with an optical microscope, and the length to the tip of the crack and the average value of the crack lengths on both surfaces of the test piece were adopted.

[Example 1]
(Preparation of Curing Agent Composition)
Curing agents were weighed in proportions shown in the table, and mixed using a stirrer at a temperature of 90° C. for 60 minutes to prepare a curing agent composition.

(Preparation of epoxy resin composition)
The curing agent composition prepared above, the epoxy resin, and the particulate rubber component were weighed in the proportions shown in the table, and mixed using a stirrer at 80° C. for 60 minutes to prepare an epoxy resin composition. In addition, in the composition shown in the table, the epoxy group of the epoxy resin and the active hydrogen of the curing agent are equivalent.

(Preparation of cured resin)
After defoaming the epoxy resin composition prepared above in a vacuum, it was injected into a stainless steel mold set to a thickness of 4 mm with a 4 mm thick silicon resin spacer. It was cured at a temperature of 180° C. for 30 minutes to obtain a resin cured product having a thickness of 4 mm.

The properties of the curing agent composition, resin composition and cured resin are shown in the table. The hardener composition remained liquid for over a week. The resin composition exhibited a low viscosity of 24 mPa·s at 100° C. and a pot life of 120 minutes. The degree of cure α was 100%, indicating rapid curability. The wet-Tg of the cured resin was 156° C., the flexural modulus was 3.4 GPa, and the K1c was 0.86 MPa·m ^1/2 , showing high mechanical properties.

[Examples 2 to 22]
The same procedure as in Example 1 was carried out except that the composition was changed as shown in the table. In the preparation of the epoxy resin composition, Examples 2 to 9 and Examples 15 to 22 were prepared at 90°C, and Examples 10 to 14 were prepared at 110°C. The properties of the curing agent composition, resin composition and cured resin are shown in the table. The hardener composition remained liquid for over a week. The resin composition exhibited a low viscosity of 32 mPa·s or less at 100° C. and a pot life of 80 minutes or more. The degree of cure α was 100% for all of them, indicating rapid curability. The wet-Tg of the cured resin was 150° C. or higher, the flexural modulus was 3.2 GPa or higher, and the K1c was 0.81 MPa·m ^1/2 or higher, showing high mechanical properties.

[Examples 23 to 25]
The same procedure as in Example 1 was carried out except that the composition was changed as shown in the table. In the preparation of the epoxy resin composition, Examples 23 and 25 were prepared at 90°C, and Example 24 was prepared at 110°C. The properties of the curing agent composition, the resin composition, and the cured resin are shown in the table. The hardener composition remained liquid for over a week. The viscosity of the resin composition was 100% for the curing degree α, indicating rapid curing. The wet-Tg of the cured resin was 156° C. or higher, and the flexural modulus was 3.2 GPa or higher, indicating high mechanical properties.

[Comparative Examples 1, 3 and 6]
The same procedure as in Example 1 was carried out except that the composition was changed as shown in the table. The properties of the hardener composition are shown in the table. In both cases, a solid precipitated within one week.

[Comparative Examples 2, 4 and 5]
The same procedure as in Example 1 was carried out except that the composition was changed as shown in the table. The properties of the cured resin are shown in the table. In all cases, the degree of cure α was less than 98, indicating insufficient rapid curability.

Claims (13)

A curing agent composition for a thermosetting resin containing a curing agent A, a curing agent B and a curing agent C,
Curing agent A is an aromatic polyamine having substituents in each of the two ortho positions to the amino group, the substituents being selected from alkyl groups, aromatic groups and halogen groups,
Curing agent B is an aromatic polyamine that is liquid at 25° C.
The curing agent C is an aromatic polyamine, characterized in that the aromatic polyamine is an aromatic polyamine that has only one electron-donating group at the ortho-position to the amino group or has no substituents at the ortho-position. , a curing agent composition for thermosetting resins. The total weight of the curing agent A, the curing agent B and the curing agent C accounts for 70 to 100% by mass based on the total mass of the curing agent composition for thermosetting resins,
The mass ratio of curing agent A and curing agent B is 1:99 to 99:1,
2. The curing agent composition for thermosetting resin according to claim 1, wherein the curing agent C is 1 to 43 parts by mass with respect to a total of 100 parts by mass of the curing agent A and the curing agent B. 3. The curing agent composition for thermosetting resin according to claim 1, wherein the electron donating group of the aromatic polyamine of the curing agent C is a methyl group, an ethyl group, a propyl group, an isopropyl group, a methoxy group or an ethoxy group. . 4. The curing agent composition for thermosetting resin according to claim 1, wherein the aromatic polyamine of curing agent C has a melting point of 150° C. or less. 5. The curing agent composition for thermosetting resin according to claim 1, wherein the aromatic polyamine of the curing agent A is an aromatic diamine. 6. The curing agent composition for thermosetting resin according to claim 5, wherein the aromatic diamine of curing agent A is a 4,4'-diaminodiphenylmethane derivative. The curing agent composition for thermosetting resins according to any one of claims 1 to 6, wherein the aromatic polyamine of curing agent B is a phenylenediamine derivative or a 4,4'-diaminodiphenylmethane derivative. Claims 1 to 7, wherein it becomes a uniform liquid at a temperature of 80 to 200 ° C., and after the liquid temperature is raised to 200 ° C., lowered to 25 ° C. and allowed to stand at 25 ° C. for one week. The curing agent composition for thermosetting resins according to any one of the above. An epoxy resin composition containing a thermosetting resin curing agent composition and an epoxy resin main agent, wherein the thermosetting resin curing agent composition is for the thermosetting resin according to any one of claims 1 to 8. Epoxy resin which is a curing agent composition and has a ratio of the number of total epoxy groups in the epoxy resin composition to the number of active hydrogens contained in the curing agent composition for thermosetting resins of 0.7 to 1.3. Composition. 10. The epoxy resin composition according to claim 9, wherein a cured product obtained by curing at 180[deg.] C. for 30 minutes has a DSC curing degree [alpha] of 98% or more, represented by the following formula.
α = (ΔH uncured - ΔH cured product) / ΔH uncured × 100
(However, ΔH is the amount of heat generated due to the curing reaction confirmed when DSC measurement is performed at a temperature increase rate of 20° C./minute, and ΔH uncured is the ΔH of the uncured epoxy resin composition, and ΔH The cured product is ΔH of the resin cured product.) A cured epoxy resin obtained by curing the epoxy resin composition according to claim 9 or 10. A fiber-reinforced composite material comprising the epoxy resin cured product according to claim 11 and a fiber-reinforced base material. 13. The fiber reinforced composite material according to claim 12, wherein the fiber reinforced substrate is a carbon fiber reinforced substrate.