WO2021020045A1

WO2021020045A1 - Epoxy resin composition for fiber-reinforced composite material, preform, and fiber-reinforced composite material

Info

Publication number: WO2021020045A1
Application number: PCT/JP2020/026542
Authority: WO
Inventors: 平野公則; 富岡伸之
Original assignee: 東レ株式会社
Priority date: 2019-07-29
Filing date: 2020-07-07
Publication date: 2021-02-04
Also published as: TW202116848A; JPWO2021020045A1

Abstract

The present invention addresses the problem of providing: an epoxy resin composition having excellent handleability at room temperature, and excellent resin impregnation properties when used as a fiber-reinforced composite material; a preform formed of the same; and a fiber-reinforced composite material.　To solve the problem, an epoxy resin composition for a fiber-reinforced composite material according to an aspect of the present invention contains a component [A] and a component [B], and contains a component [b] as the component [B], wherein the difference in melting point between the component [A] and the component [B] is 0-60ºC, and the content of a crystalline component is at least 70 mass%. Component [A] is a crystalline epoxy resin. Component [B] is a crystalline curing agent. Component [b] is a crystalline curing agent composed of two or more crystalline monomer compounds and having a single melting point.

Description

Epoxy resin compositions and preforms for fiber reinforced composites and fiber reinforced composites

The present invention relates to an epoxy resin composition used for a fiber-reinforced composite material, a preform made by using the epoxy resin composition, and a fiber-reinforced composite material.

Fiber-reinforced composite materials consisting of reinforcing fibers and matrix resins can be designed to take advantage of the advantages of reinforcing fibers and matrix resins, so their applications are expanding to the aerospace field, sports field, and general industrial fields. ..

As the reinforcing fiber, glass fiber, aramid fiber, carbon fiber, boron fiber and the like are used. Further, as the matrix resin, both a thermosetting resin and a thermoplastic resin are used, but a thermosetting resin that can be easily impregnated into the reinforcing fibers is often used. As the thermosetting resin, an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, a phenol resin, a bismaleimide resin, a cyanate resin and the like are used.

Generally, the production of fiber-reinforced composite materials includes a prepreg method, a hand lay-up method, a filament winding method, a pull-fusion method, an RTM (Resin Transfer Molding: resin injection molding) method, a film bag molding method, a press molding method, and the like. The method applies. In particular, when productivity is required, an RTM molding method, a film bag molding method, and a press molding method, which are excellent in productivity, are preferably used.

In recent years, demand for fiber-reinforced composite materials such as carbon fiber-reinforced composite materials has been increasing, especially for aircraft and automobile applications. In these applications, in order to apply the fiber-reinforced composite material more universally, a material and a molding method having a low cost and a low environmental load are required.

The matrix resin used in the conventional method for producing a fiber-reinforced composite material as described above uses a liquid or semi-solid resin at room temperature in order to sufficiently impregnate the reinforcing fiber base material. There is. When a liquid or semi-solid resin is used at room temperature, a large amount of loss occurs because the resin tends to remain in the resin compounding equipment and the resin injection equipment. Further, for example, when the prepreg method is applied, it is a step of first producing a matrix resin film and then impregnating the produced film with the reinforcing fibers, but when the resin film is produced, an auxiliary material such as a releasable film is used. It is often required and tends to be costly. Further, in order to obtain a resin composition that is liquid or semi-solid at room temperature, it is difficult to add a large amount of solid components at room temperature.

On the other hand, when a fiber-reinforced composite material is molded using a solid resin at room temperature, it is easy to reduce the loss due to the resin remaining in equipment such as liquid resin, and it is possible to reduce the amount of auxiliary materials. , Impregnation property into the reinforcing fiber base material can be a problem.

Patent Document 1 describes a resin composition for use in fiber-reinforced composite materials, which comprises a crystalline epoxy resin, a crystalline acid anhydride curing agent, and a crystalline curing accelerator, which is solid at room temperature but has excellent impregnation property into a substrate. The thing is disclosed.

Patent Document 2 describes a resin composition that is solid at room temperature and is composed of a crystalline epoxy resin and a crystalline curing accelerator for use in fiber-reinforced composite materials, and the resin composition is dissolved in an organic solvent to form a resin varnish. Is disclosed as a method for impregnating a sheet-shaped fiber base material with.

Patent Document 3 discloses a resin composition comprising a glassy solid epoxy resin and a crystalline acid anhydride curing agent for an optical semiconductor encapsulating material.

Patent Document 4 discloses a resin composition using an amine curing agent that facilitates compatibility with an epoxy resin as a glassy solid by melting a high melting point crystalline amine once and then quenching it.

International Publication No. 2019/003824 International Publication No. 2008/059755 JP-A-2010-202758 International Publication No. 2016/089724

The materials described in Patent Document 1 are limited in selectable compounds in order to obtain excellent impregnation properties.

The material described in Patent Document 2 aims to have crystallinity when it is made into a cured product, and when it is impregnated into a reinforcing fiber base material without using a solvent, it is melted by a crystalline component contained in the resin composition. Since the temperatures are different, the fibers are impregnated with the melted components first, and as a result, when this material is used as a fiber-reinforced composite material, the cured resin is likely to have uneven composition.

The material described in Patent Document 3 differs in melting behavior when heated between a glassy solid epoxy resin and a crystalline acid anhydride curing agent, and when this material is used as a fiber-reinforced composite material, it is composed of a cured resin. It was a material that was prone to unevenness.

The material described in Patent Document 4 is a material in which unevenness is likely to occur when the fiber-reinforced base material is impregnated because the viscosity of the amine curing agent made into a glassy solid gradually decreases when the temperature is raised and heated.

An object of the present invention is an epoxy resin composition that improves the above-mentioned drawbacks of the prior art and is excellent in handleability at room temperature and resin impregnation when used as a fiber-reinforced composite material, and a preform made by using the same. , As well as providing fiber reinforced composite materials.

The present invention for solving the above problems has the following configuration.

(1) The component [A] and the component [B] are contained, and the component [B] is contained as the component [B], and the difference in melting point between the component [A] and the component [B] is 0 to 60 ° C. An epoxy resin composition for a fiber-reinforced composite material containing 70% by mass or more of a crystalline component.
Component [A]: Crystalline epoxy resin component [B]: Crystalline curing agent component [b]: Crystalline curing agent (2) component composed of two or more kinds of crystalline monomer compounds and having a single melting point. It contains [A] and component [B], and also contains component [a] as component [A], and the difference in melting point between component [A] and component [B] is 0 to 60 ° C. An epoxy resin composition for a fiber-reinforced composite material containing 70% by mass or more.
Component [A]: Crystalline epoxy resin component [a]: Crystalline epoxy resin component [B]: which is composed of two or more kinds of crystalline monomer compounds and has a single melting point: Crystalline curing agent (3) A preform having the epoxy resin composition for a fiber-reinforced composite material according to (1) or (2) and a dry-reinforced fiber base material.

(4) A fiber-reinforced composite material obtained by impregnating and curing a dry-reinforced fiber base material with the epoxy resin composition for a fiber-reinforced composite material of the preform according to (3) above.

According to the present invention, an epoxy resin composition having excellent handleability at room temperature and resin impregnation property when used as a fiber-reinforced composite material, a preform made by using the epoxy resin composition, and a fiber-reinforced composite material can be obtained. ..

The preferred embodiment of the present invention will be described below.

The first aspect of the epoxy resin composition for a fiber-reinforced composite material of the present invention contains a component [A] and a component [B], and also contains a component [b] as a component [B], and the component [A] and An epoxy resin composition for a fiber-reinforced composite material in which the difference in melting point of the component [B] is 0 to 60 ° C. and the crystalline component is contained in an amount of 70% by mass or more.
Component [A]: Crystalline epoxy resin component [B]: Crystalline curing agent Component [b]: A crystalline curing agent composed of two or more kinds of crystalline monomer compounds and having a single melting point.

In addition, the second aspect of the epoxy resin composition for a fiber-reinforced composite material of the present invention contains a component [A] and a component [B], and also contains a component [a] as a component [A], and contains a component [A]. ] And the component [B] have a difference in melting point of 0 to 60 ° C., and are an epoxy resin composition for a fiber-reinforced composite material containing 70% by mass or more of a crystalline component.
Component [A]: Crystalline epoxy resin component [a]: Crystalline epoxy resin component [B]: a crystalline epoxy resin component [B]: which is composed of two or more kinds of crystalline monomer compounds and has a single melting point.

The epoxy resin composition for a fiber-reinforced composite material of the present invention tends to be less likely to limit the crystalline components that can be used as compared with the prior art (for example, the technique described in Patent Document 1).

In the present invention, the "epoxy resin composition for fiber-reinforced composite material" may be simply referred to as "epoxy resin composition".

Component [A] contained in the epoxy resin composition of the present invention: The crystalline epoxy resin is a monomer component in which a curing reaction proceeds by heating to form a crosslinked structure, and one or more, preferably two, are contained in one molecule. It is a compound having the above epoxy group and having crystallinity. Such a crystalline epoxy resin may be composed of only one kind of compound having an epoxy group and having crystallinity, or may be a mixture of a plurality of kinds.

Here, having crystallinity means a component that has a melting point at a temperature higher than room temperature and is solid at room temperature. The melting point can be determined by differential scanning calorimetry (DSC) according to JIS K 7121: 2012. The temperature of the crystalline component can be measured by raising the temperature in a nitrogen atmosphere, and the peak temperature of the endothermic peak in the obtained DSC curve can be obtained as the melting point. The normal temperature means 25 ° C.

Since the epoxy resin composition of the present invention contains the component [A]: crystalline epoxy resin, it is easy to handle at room temperature and melts at high temperature to become a low-viscosity liquid, which is impregnated into the reinforcing fiber base material. Easy to excel in sex.

Component [A] preferably used in the present invention: The crystalline epoxy resin is obtained from an aromatic glycidyl ether obtained from a phenol compound having a plurality of hydroxyl groups, an aliphatic glycidyl ether obtained from an alcohol compound having a plurality of hydroxyl groups, and an amine compound. Among the glycidyl amines, glycidyl esters obtained from carboxylic acid compounds having a plurality of carboxyl groups, and the like, various epoxy resins having crystalline properties can be mentioned.

Specifically, although not particularly limited, bisphenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, hydroquinone type epoxy resin, thioether type epoxy resin, phenylene ether type epoxy resin, Among trishydroxyphenylmethane type epoxy resin, terephthalic acid type epoxy resin, isocyanuric acid type epoxy resin, phthalimide type epoxy resin, tetraphenylethane type epoxy resin and the like, it is an epoxy resin having crystallinity.

Among the crystalline epoxy resins, it is preferable to use a bifunctional crystalline epoxy resin because the crosslink density when made into a cured product does not easily increase and it is easy to obtain excellent heat resistance while maintaining the plastic deformation ability. The bifunctional crystalline epoxy resin is a compound having two epoxy groups in one molecule and having crystallinity.

In the epoxy resin composition of the present invention, it is preferable that the component [A] contains a biphenyl type epoxy resin from the viewpoint of heat resistance and handleability.

Component [A]: The crystalline epoxy resin is preferably contained in an amount of 30% by mass or more, more preferably 50% by mass or more, in 100% by mass of the epoxy resin composition. By containing 30% by mass or more in 100% by mass of the epoxy resin composition, the handleability of the resin composition at room temperature and the heat resistance of the cured product are easily improved.

The epoxy resin composition of the present invention may contain another epoxy resin in combination with the component [A]: crystalline epoxy resin. The other epoxy resin is a compound having one or more epoxy groups in one molecule, and may be in any form of liquid, semi-solid, or glassy solid at room temperature.

Component [B] contained in the epoxy resin composition of the present invention: Among the compounds that cure the epoxy resin by reacting with the epoxy group contained in the molecule of the thermosetting resin and covalently bonding the crystalline curing agent. , A compound having crystallinity.

Component [B]: Compounds that can be used as a crystalline curing agent include, for example, compounds having an amino group, compounds having a hydroxyl group, compounds having an acid anhydride, compounds having a carboxylic acid, and compounds having a thiol group. Among compounds having an isocyanate group, compounds having crystalline properties can be used.

Since the epoxy resin composition of the present invention contains the component [B]: crystalline curing agent, it is easy to handle at room temperature and melts at high temperature to become a low-viscosity liquid, which is impregnated into the reinforcing fiber base material. Easy to excel in sex.

Examples of the compound having an amino group include dicyandiamide, aromatic polyamine, aliphatic amine, aminobenzoic acid esters, thiourea-added amine, hydrazide and the like, which have crystalline properties. As the phenol-based curing agent, among bisphenol, phenol novolac resin, cresol novolac resin, polyphenol compound and the like, a crystalline compound can be exemplified. Examples of the acid anhydride-based curing agent include crystalline compounds among phthalic anhydride, maleic anhydride, succinic anhydride, and carboxylic acid anhydride. As the mercaptan-based curing agent, among polymercaptan, polysulfide resin and the like, a compound having crystallinity can be exemplified.

Among the crystalline curing agents, the crystalline amine curing agent is easy to handle at room temperature, the crosslink density when it is made into a cured product is unlikely to increase, the plastic deformation ability is easily maintained, and high heat resistance is easily obtained. , Can be preferably used.

As the crystalline amine curing agent preferably used in the present invention, either an aliphatic amine or an aromatic amine can be used, but it is preferable to use an aromatic polyamine from the viewpoint of heat resistance of the cured product. The aromatic polyamine among the crystalline amine curing agents is not particularly limited, but is not particularly limited, but is diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiphenyl ether, bisaniline M, bisaniline P, bisaminophenoxybenzene, bisaminophenoxyphenylpropane, bis. Among aminophenoxyphenyl sulfone, bisaminophenylfluorene and derivatives thereof, or various isomers thereof, those having crystallinity can be preferably used. In particular, from the viewpoint of heat resistance and handleability, it is more preferable to use diaminodiphenylmethane, diaminodiphenylsulfone, bisaminophenylfluorene and derivatives thereof, or various isomers thereof having crystalline properties. Above all, it is more preferable that the component [B] contains diaminodiphenyl sulfone.

A first aspect of the epoxy resin composition of the present invention is a crystalline component [B]: a crystalline curing agent, which is composed of two or more crystalline monomer compounds of the component [b] and has a single melting point. Contains hardener. In addition, the second aspect of the epoxy resin composition of the present invention is composed of two or more kinds of crystalline monomer compounds of the component [b] as a component [B]: a crystalline curing agent, and has a single melting point. It may contain a crystalline hardener. Here, the “crystalline monomer compound” is defined as component [B]: each component of the two or more kinds of crystalline curing agents when the crystal curing agent contains two or more kinds of crystalline curing agents, that is, Represents one type and one type of crystalline curing agent. Such two or more kinds of components are preferably crystalline curing agents having similar skeletons to each other. By using crystalline curing agents having similar skeletons to each other, two or more kinds of crystalline monomer components tend to have a single melting point.

In a mixture crystal (eutectic) in which two or more kinds of monomer compounds having such crystallinity are mixed, a phenomenon of melting point decrease may be observed in which the melting point is lower than the melting point of a single compound having crystallinity. is there. Therefore, the melting point of the component [b] is preferably lower than the melting point of each of the crystalline monomer compounds contained in the component [b]. Since the melting point of the component [b] is lower than the melting point of each of the crystalline monomer compounds contained in the component [b], it is easy to control the melting behavior of the resin composition, and the reinforcing fiber base material is impregnated. It becomes easier to improve the sex.

Component [b]: A crystalline curing agent composed of two or more kinds of crystalline monomer compounds and having a single melting point is prepared by, for example, melting two or more kinds of constituent crystalline monomer compounds once, uniformly mixing them, and then slowly mixing them. It can be prepared by a method of cooling to a vicinity of the crystallization temperature and crystallinizing, a method of dissolving two or more kinds of constituent crystalline curing agent components in a solvent, and then crystallizing by lowering the temperature or dropping a poor solvent. From the viewpoint of eutectic uniformity, it is preferable to melt once, mix uniformly, and then slowly cool to near the crystallization temperature to crystallize. At this time, the eutectic obtained from the two or more kinds of crystalline monomer compounds constituting the compound is irreversible (that is, the obtained mixture crystal has two or more kinds of crystallinity by physical operations such as heating and mixing. It does not return to the state of a monomer compound).

It should be noted that having a single melting point means that the crystalline component is heated in a nitrogen atmosphere by differential scanning calorimetry (DSC) according to JIS K 7121: 2012, and the obtained DSC curve has two or more endothermic peaks. Refers to not separating into. The fact that the endothermic peak is not separated into two means that both ends of the endothermic peak do not drop to the baseline and become a continuous endothermic peak, and even if it has two or more peaks, it does not drop to the baseline. Has a single melting point.

In the present invention, the component [B]: crystalline curing agent is preferably contained in an amount of 10% by mass or more, more preferably 15% by mass or more, and 20% by mass or more in 100% by mass of the epoxy resin composition. It is even more preferable. When 10% by mass or more is contained in 100% by mass of the epoxy resin composition, the handleability of the resin composition at room temperature becomes easy to be excellent.

The epoxy resin composition may contain another curing agent in combination with the component [B]: crystalline curing agent. The other curing agent may be any compound having an active group capable of reacting with one or more epoxy groups in one molecule, and may be in the form of liquid, semi-solid or glassy solid at room temperature.

The epoxy resin composition can further contain component [C]: a crystalline curing accelerator. The crystallinity curing accelerator is a component that rapidly smoothes the curing reaction by forming a bond between the epoxy resin and the curing agent, and is a compound having crystallinity. By including the crystalline curing accelerator, the curing time may be shortened and the productivity may be improved. As described above, having crystallinity means a component having a melting point at a temperature higher than room temperature and being solid at room temperature.

Examples of the crystalline curing accelerator that can be used in the present invention include imidazoles, tertiary amines, organophosphorus compounds, urea compounds, phenol compounds, ammonium salts, sulfonium salts, and the like, which have crystalline properties. In particular, from the viewpoint of curability and stability, it is preferable to use organic phosphorus compounds, urea compounds, phenol compounds and the like having crystallinity.

Component [C]: The crystalline curing accelerator is preferably contained in an amount of 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, in 100% by mass of the epoxy resin composition. By containing 0.1 to 10% by mass in 100% by mass of the epoxy resin composition, it may be possible to shorten the curing time while ensuring the stability of the epoxy resin composition at room temperature.

In such an epoxy resin composition, in 100 parts by mass of the epoxy resin composition, the content of all crystalline components is 70% by mass or more and 100% by mass or less, and preferably 80% by mass or more and 100% by mass or less. , 90% by mass or more and 100% by mass or less is more preferable. Here, the content of all crystalline components means that a plurality of different crystalline components are contained (specifically, component [A], component [B], and if contained, component [C], In addition, when it has a melting point at a temperature higher than normal temperature and contains a solid component at normal temperature), it means the total content thereof. When the total content of the crystalline components is 70% by mass or more, the epoxy resin composition is excellent in handleability at room temperature and also excellent in impregnation property into dry reinforcing fibers when heated and melted.

In such an epoxy resin composition, the difference in melting point between the component [A] and the component [B] is 0 to 60 ° C., preferably 0 to 50 ° C., and more preferably 0 to 40 ° C. When the difference in melting point between the component [A] and the component [B] is larger than 60 ° C., the meltability of the components differs when the composition is heated, so that the obtained cured product becomes non-uniform. When the component [A] or the component [B] has a plurality of melting points, it refers to the difference in melting points in the combination in which the difference in melting points is the largest.

In the present invention, when the component [b] is included as the component [B], the melting point of the crystalline curing agent is controlled by the phenomenon of melting point drop, and the difference between the melting points of the above component [A] and the component [B] is 0. It can be easily set to -60 ° C.

A first aspect of the epoxy resin composition of the present invention is as a component [A]: a crystalline epoxy resin, which is composed of two or more kinds of crystalline monomer compounds of the component [a] and has a single melting point. It may contain an epoxy resin. In addition, the second aspect of the epoxy resin composition of the present invention is composed of two or more kinds of crystalline monomer compounds of the component [a] as the component [A]: crystalline epoxy resin, and has a single melting point. Contains crystalline epoxy resin. Here, the "crystalline monomer compound" is defined as a component [A]: each component of the two or more kinds of crystalline epoxy resin when the crystalline epoxy resin contains two or more kinds of crystalline epoxy resin, that is, Represents one type and one type of crystalline epoxy resin. Such two or more kinds of components are preferably crystalline epoxy resins having similar skeletons to each other. By using crystalline epoxy resins having similar skeletons to each other, two or more kinds of crystalline monomer components tend to have a single melting point.

Regarding the component [a] as well, by controlling the melting point of the crystalline component by utilizing the phenomenon of the melting point drop, it becomes easy to improve the impregnation property of the resin composition into the fiber-reinforced base material. At this time, the mixture crystal obtained from the two or more kinds of crystalline monomer compounds constituting the compound is irreversible (that is, the obtained eutectic is crystallinity of two or more kinds by physical operations such as heating and mixing. It does not return to the state of a monomer compound).

The epoxy resin composition of the present invention preferably has a complex viscosity η ^{* at} 25 ° C. of 1 × 10 ⁷ Pa · s or more, and more preferably 3 × 10 ⁷ Pa · s or more. When the complex viscosity η ^{* at} 25 ° C. is 1 × 10 ⁷ Pa · s or more, the composition does not easily flow at room temperature, and the handleability tends to be improved. The complex viscosity η ^* of the epoxy resin composition can be measured by setting a resin sample on a parallel plate and using a dynamic viscoelasticity measuring device.

The method for preparing the epoxy resin composition of the present invention is not particularly limited, but for example, the constituent components may be once heated and phase-dissolved, then cooled and recrystallized to obtain an epoxy resin composition. Alternatively, the epoxy resin composition may be obtained by crimping the powders together after mixing the constituent solid components into powders. In particular, from the viewpoint of storage stability, a method of preparing by crimping after powdering is preferable. By preparing the constituent components in powder form by crimping, each component is not uniformly compatible at the molecular level and is dispersed in a state having a domain on the order of micrometers. Improves reaction stability during storage.

The epoxy resin composition as described above can be produced, for example, by sufficiently mixing the powdered raw materials of each component, pressurizing the mixture, and crimping each component. The pressurizing pressure at this time is preferably 2 to 100 MPa, more preferably 5 to 50 MPa. The pressure range may be a combination of the upper limit and the lower limit of the pressure range. By setting the pressure in the range of 2 to 100 MPa, each component can be sufficiently pressure-bonded, and the handleability of the resin composition can be easily improved.

The form of the epoxy resin composition of the present invention is not particularly limited, but various forms such as lumps, rods, plates, films, fibers, and granules can be used. In particular, from the viewpoint of impregnation property into the reinforcing fiber and handleability, it is preferably lumpy, plate-like or granule.

The epoxy resin composition of the present invention preferably has a major axis of 1.5 mm or more, more preferably a major axis of 3 mm or more, and further preferably a major axis of 10 mm or more. When the major axis is less than 1.5 mm, air is likely to be contained when the resin composition is heated and melted and impregnated into the fiber-reinforced base material, and when the resin is cured, the amount of voids inside the molded product increases and the strength is increased. The characteristics tend to deteriorate. The major axis refers to the length of the longest portion of the epoxy resin composition. The upper limit of the major axis is not particularly limited, but is usually about 1 m (1000 mm).

The epoxy resin composition of the present invention is preferably used as a preform in combination with a dry reinforcing fiber base material.

The preform of the present invention has the epoxy resin composition for a fiber-reinforced composite material of the present invention and a dry-reinforced fiber base material. More specifically, the preform of the present invention is in the form in which the epoxy resin composition is in direct or indirect contact with the surface of the dry reinforcing fiber base material. For example, the epoxy resin composition may be present on the dry reinforcing fiber base material, or the dry reinforcing fiber base material may be present on the epoxy resin composition. It may be in a laminated form. Further, the epoxy resin composition and the dry reinforcing fiber base material may be in a form of indirect contact with each other via a film, a non-woven fabric or the like.

Various organic and inorganic fibers such as glass fiber, aramid fiber, carbon fiber and boron fiber are used as the dry reinforcing fiber base material according to the present invention. Among them, carbon fiber is preferably used because it is possible to obtain a fiber-reinforced composite material which is lightweight but has excellent mechanical properties such as strength and elastic modulus.

In the present invention, the dry reinforcing fiber base material refers to a reinforcing fiber base material in a state in which the reinforcing fiber base material is not impregnated with the matrix resin. Therefore, the preform of the present invention is different from the prepreg in which the reinforcing fibers are impregnated with the matrix resin. However, the dry reinforcing fiber base material in the present invention may be impregnated with a small amount of binder. The binder is a component that binds between layers of the laminated dry reinforcing fiber base material, and a component made of a thermoplastic resin that does not contain a curing agent or a catalyst is preferable. Further, in the fiber-reinforced composite material of the present invention described later, since the epoxy resin composition is impregnated and cured, it is not called a dry-reinforced fiber.

The dry reinforcing fiber in the present invention may be either a short fiber or a continuous fiber, and both can be used in combination. In order to obtain a fiber-reinforced composite material having a high fiber volume content (high Vf), continuous fibers are preferably used.

The dry reinforcing fiber in the present invention may be used in the form of a strand, but a dry reinforcing fiber base material obtained by processing the dry reinforcing fiber into a form such as a mat, a woven fabric, a knit, a blade, and a unidirectional sheet is preferably used. .. Among them, a woven fabric in which a fiber-reinforced composite material having a high Vf is easily obtained and has excellent handleability is preferably used.

In order to have a high specific strength or a specific elastic modulus when the fiber-reinforced composite material of the present invention is used, the fiber volume content Vf of the reinforcing fibers is preferably 30 to 85%, more preferably 35 to 70. It is in the range of%. The fiber volume content Vf of the fiber-reinforced composite material referred to here is a value defined and measured as follows in accordance with ASTM D3171 (1999). That is, it refers to a value measured in a state after the dry reinforcing fiber base material is impregnated with the epoxy resin composition and the composition is cured. Therefore, the measurement of the fiber volume content Vf of the fiber-reinforced composite material can be expressed by using the following formula (2) from the thickness h of the fiber-reinforced composite material.

-Fiber volume content Vf (%) = (Af × N) / (ρf × h × 10) ・・・ (2)
・ Af: 1 dry reinforcing fiber base material ・ Mass per 1 m ² (g / m ² )
・ N: Number of laminated dry reinforcing fiber base materials (sheets)
-Ρf: Density of dry reinforcing fiber base material (g / cm ³ )
-H: Thickness (mm) of the fiber-reinforced composite material (test piece).

If the mass Af per 1 m ^{2 of} the dry reinforcing fiber base material, the number of laminated dry reinforcing fiber base materials N, and the density ρf of the dry reinforcing fiber base material are not clear, a combustion method based on JIS K 7075 (1991). , The fiber volume content of the fiber-reinforced composite material is measured by either the nitrate decomposition method or the sulfate decomposition method. For the density of the reinforcing fibers used in this case, a value measured based on JIS R 7603 (1999) is used.

As a specific method for measuring the thickness h of the fiber-reinforced composite material, as described in JIS K 7072 (1991), it has a micrometer specified in JIS B 7502 (1994) or an accuracy equal to or higher than that. It is preferable to measure with a thing. If the fiber-reinforced composite has a complicated shape and the thickness cannot be measured, a sample (a sample having a certain shape and size for measurement) is cut out from the fiber-reinforced composite. It is desirable to measure.

The fiber-reinforced composite material of the present invention is obtained by impregnating and curing a dry-reinforced fiber base material with an epoxy resin composition for a fiber-reinforced composite material of the preform of the present invention. That is, the fiber-reinforced composite material of the present invention comprises a dry-reinforced fiber base material and a cured product of an epoxy resin composition, and the epoxy resin composition is impregnated into the dry-reinforced fiber base material and cured. Is. That is, the fiber-reinforced composite material of the present invention can be obtained by impregnating the dry reinforcing fiber base material with the epoxy resin composition of the present invention, molding the mixture, and curing the epoxy resin composition.

The method for producing a fiber-reinforced composite material of the present invention includes a molding step of molding while impregnating the reinforcing fibers with a thermosetting epoxy resin composition, and a curing step of curing to obtain a fiber-reinforced composite material.

Various methods such as a press molding method, a film bag molding method, and an autoclave molding method can be used for producing the fiber-reinforced composite material of the present invention. Of these, the press molding method and the film bag molding method are particularly preferably used from the viewpoint of productivity and the degree of freedom in the shape of the molded product.

In the film bag molding method, a preform composed of an epoxy resin composition and a dry reinforcing fiber base material is placed between a rigid open mold and a flexible film, and the inside is evacuated to apply atmospheric pressure. It is preferably exemplified by heat molding while pressurizing with a gas or liquid.

The method for producing the fiber-reinforced composite material of the present invention will be described using an example of the press molding method. In the fiber-reinforced composite material of the present invention, a preform for a fiber-reinforced composite material composed of an epoxy resin composition and a dry-reinforced fiber base material is placed in a molding mold heated to a specific temperature, and then pressed and heated by a press. As a result, the resin composition can be produced by melting, impregnating the reinforcing fiber base material, and then curing as it is.

The temperature of the molding die is preferably set to a temperature equal to or higher than the temperature at which the complex viscosity η ^* of the resin composition used is lowered to 1 × 10 ¹ Pa · s from the viewpoint of impregnation property into the dry reinforcing fiber base material.

Hereinafter, the present invention will be described in more detail with reference to Examples.

<Resin raw material>
The following resin raw materials were used to obtain the epoxy resin compositions of each example. The unit of the content ratio of the epoxy resin composition in Table 1 means "part by mass" unless otherwise specified.

1. 1. Ingredient [A]: Crystalline epoxy resin-"jER (registered trademark)" YX4000 (manufactured by Mitsubishi Chemical Corporation): Tetramethylbiphenyl type epoxy resin, melting point = 105 ° C.
-"JER (registered trademark)" YL6121H (manufactured by Mitsubishi Chemical Corporation): Eutectic of tetramethylbiphenyl type epoxy resin and biphenyl type epoxy resin, melting point = 120 ° C.
-YSLV-80XY (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.): Bisphenol F type epoxy resin, melting point = 81 ° C
-TEPIC-S (manufactured by Nissan Chemical Industries, Ltd.): Isocyanuric acid type epoxy resin, melting point = 110 ° C.

2. 2. Other epoxy resins- "jER (registered trademark)" 1001 (manufactured by Mitsubishi Chemical Co., Ltd.): Bisphenol A type epoxy resin, glassy solid.

3. 3. Ingredient [B]: Crystalline amine curing agent-Seika Cure S (manufactured by Wakayama Seika Kogyo Co., Ltd.): 4,4'-diaminodiphenyl sulfone, melting point = 176 ° C.
・ 3,3'-DAS (manufactured by Konishi Chemical Industry Co., Ltd.): 3,3'-diaminodiphenyl sulfone, melting point = 170 ° C
-"Lonza cure (registered trademark)" M-DEA (manufactured by Lonza Co., Ltd.): 4,4'-diamino-3,3', 5,5'-tetraethyldiphenylmethane, melting point = 89 ° C.
"Lonzacure (registered trademark)" CAF (manufactured by Lonza Co., Ltd.): 9,9-bis (4-amino-3-chlorophenyl) fluorene, melting point = 201 ° C.

Bisphenol A (manufactured by Kanto Chemical Co., Inc.): 4,4'-isopropyridene diphenol, melting point = 158 ° C.

-"Ricacid (registered trademark)" TH (manufactured by New Japan Chemical Co., Ltd.): 1,2,3,6-tetrahydrophthalic anhydride, melting point = 101 ° C.
4. Ingredient [C]: Crystalline curing accelerator-TPP (manufactured by Keiai Kasei Co., Ltd.): Triphenylphosphine, melting point = 80 ° C.

<Preparation of epoxy resin composition>
The resin raw materials listed in Table 1 are pulverized with a hammer mill (PULVERIZER, manufactured by Hosokawa Micron Co., Ltd.) using a screen with a hole size of 1 mm, and then passed through a sieve with an opening size of 212 μm to form a powder. Obtained raw material. Then, using the classified powdery raw material, the raw materials are sufficiently mixed at the blending ratio as shown in Table 1, 80 g is put into a 10 cm square mold, and the pressure is applied at 3 MPa to obtain a thermosetting resin composition. Got

<Measurement of melting point of crystalline component>
The melting point of each resin raw material used was measured by differential scanning calorimetry (DSC) according to JIS K 7121: 2012. As a measuring device, Pyris1 DSC (manufactured by PerkinElmer) was used. The crystalline component is collected in an aluminum sample pan and measured at a heating rate of 10 ° C./min in a nitrogen atmosphere. In the obtained DSC curve, the temperature at the apex of the endothermic peak due to melting of the components was measured as the melting point. Of the components [b] listed in Table 1, those in the column of "eutectic of the components described in component [b]" are uniformly melted once by melting the two types of crystalline monomer compounds shown in Table 1. After compatibilization, it was prepared by recrystallization near the crystallinity temperature.

<Complex viscosity η ^* measurement of epoxy resin composition>
The epoxy resin composition prepared as described above was used as a sample and measured by dynamic viscoelasticity measurement. ARES-G2 (manufactured by TA Instruments) was used as the measuring device. The sample was set on an 8 mm parallel plate, a traction cycle of 0.5 Hz was added, and the sample was measured at room temperature to measure the complex viscosity η ^* .

<Handability of thermosetting resin composition at room temperature>
The handleability of the epoxy resin composition prepared as described above at room temperature was comparatively evaluated in the following three stages. When the epoxy resin composition is lifted by hand, the one that is not broken or deformed is "A", the one that is partially chipped or slightly deformed is "B", and the one that is easily cracked or deformed when lifted The one that is stored is designated as "C".

<Preparation of fiber reinforced composite material>
A fiber-reinforced composite material was produced by the following press molding method. Carbon fiber woven fabric CO6343 (carbon fiber: T300-3K) as a dry reinforcing fiber base material in a mold having a plate-shaped cavity of 350 mm × 700 mm × 2 mm and held at a predetermined temperature (mold temperature described later). A preform in which 290 g of the epoxy resin composition prepared as described above was arranged was set on a base material obtained by laminating 9 sheets of plain weave, texture: 198 g / m ² , manufactured by Toray Industries, Inc. After that, the mold was fixed with a press device. At this time, the inside of the die was depressurized to atmospheric pressure −0.1 MPa by a vacuum pump, and then pressed at a maximum pressure of 4 MPa. The mold temperature was set to a temperature 10 ° C. higher than the temperature of the highest melting point of the crystalline components contained in the thermosetting resin composition used. However, when the temperature was 180 ° C. or lower, it was set to 180 ° C. The mold was opened and demolded 4 hours after the start of pressing to obtain a fiber-reinforced composite material.

<Resin impregnation into dry reinforcing fiber base material>
The impregnation property of the resin into the dry-reinforced fiber base material when producing the fiber-reinforced composite material was comparatively evaluated in the following three stages based on the amount of voids in the fiber-reinforced composite material.

If no resin-impregnated portion is observed in the appearance of the fiber-reinforced composite material and the amount of voids in the fiber-reinforced composite material is less than 1%, "A" is used for the fiber-reinforced composite material. Although no resin-impregnated portion is observed in the appearance, "B" is used for the fiber-reinforced composite material having a void amount of 1% or more, and "C" is used for the fiber-reinforced composite material in which the resin-unimpregnated portion is observed. ".

The appearance of the fiber-reinforced composite material was visually observed. The amount of voids in the fiber-reinforced composite material is determined by observing the surface of the fiber-reinforced composite material arbitrarily selected by the smooth-polished fiber-reinforced composite material with a smooth-polished cross section with a tilting optical microscope, and the area of the voids in the fiber-reinforced composite material. Calculated from the rate.

<Composition unevenness of fiber reinforced composite material>
The composition unevenness of the fiber-reinforced composite material (350 mm × 700 mm × 2 mm) obtained according to the above <Preparation of fiber-reinforced composite material> was comparatively evaluated in the following three stages.

The sample was uniformly cut at 100 mm intervals in the long direction (700 mm) and 100 mm intervals in the short direction (350 mm) with respect to the plane direction of the obtained fiber-reinforced composite material, and 21 samples were cut out. It was. As a result of measuring the glass transition temperature (Tg) of the fiber-reinforced composite material by differential scanning calorimetry (DSC) according to JIS K 7121: 2012 for each sample, the difference between the maximum value and the minimum value of the measurement result is less than 15 ° C. Those having a temperature of 15 ° C. or higher were designated as "A", those having a temperature of 15 ° C. or higher and lower than 30 ° C. were designated as "B", and those having a temperature of 30 ° C. or higher were designated as "C".

(Example 1)
As shown in Table 1, 100 parts by mass of the tetramethylbiphenyl type epoxy resin "" jER (registered trademark) "YX4000" and 4,4'-diamino whose melting point was lowered to 137 ° C by eutectic in advance. After thoroughly mixing 17 parts by mass of diphenyl sulfone "Seika Cure S" and 17 parts by mass of 3,3'-diaminodiphenyl sulfone "3,3'-DAS" eutectic powder, and putting 80 g into a 10 cm square mold, A plate-shaped epoxy resin composition was prepared by pressurizing at a pressure of 3 MPa. This resin composition was excellent in handleability at room temperature without being deformed even when lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had almost no unimpregnated portion on the surface or voids inside, and was excellent in impregnation property. As a result of uniformly cutting out 17 samples from the fiber-reinforced composite material and measuring Tg, a uniform fiber-reinforced composite material was obtained with almost no unevenness depending on the position.

(Example 2)
As shown in Table 1, the blending ratio of 4,4'-diaminodiphenyl sulfone "Seikacure S" and 3,3'-diaminodiphenyl sulfone "3,3'-DAS" of the component [B] used is 2: An epoxy resin composition was prepared in the same manner as in Example 1 except that the value was 1. This resin composition was excellent in handleability at room temperature without being deformed even when lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had almost no unimpregnated portion on the surface or voids inside, and was excellent in impregnation property. In addition, as a result of Tg measurement, a uniform fiber-reinforced composite material was obtained with almost no unevenness depending on the position.

(Example 3)
As shown in Table 1, the blending ratio of 4,4'-diaminodiphenyl sulfone "Seikacure S" and 3,3'-diaminodiphenyl sulfone "3,3'-DAS" of the component [B] used is 9: An epoxy resin composition was prepared in the same manner as in Example 1 except that the value was 1. This resin composition was excellent in handleability at room temperature without being deformed even when lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had sufficient impregnation property although some internal voids were observed on the surface. Further, as a result of Tg measurement, a sufficiently uniform fiber-reinforced composite material was obtained, although some unevenness was observed depending on the position.

(Example 4)
As shown in Table 1, the components [B] used are 23 parts by mass of 4,4'-diaminodiphenyl sulfone "Seikacure S" and 4,4'-diamino-3,3', 5,5'-tetraethyldiphenylmethane. An epoxy resin composition was prepared in the same manner as in Example 1 except that "Lonzacure (registered trademark)" M-DEA was made up of 15 parts by mass. This resin composition had sufficient handleability at room temperature even when it was lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had almost no unimpregnated portion on the surface or voids inside, and was excellent in impregnation property. Further, as a result of Tg measurement, a sufficiently uniform fiber-reinforced composite material was obtained, although some unevenness was observed depending on the position.

(Example 5)
As shown in Table 1, the component [B] used was 23 parts by mass of 4,4'-diaminodiphenyl sulfone "Seikacure S" and 9,9-bis (4-amino-3-chlorophenyl) fluorene "" Lonzacure ( An epoxy resin composition was prepared in the same manner as in Example 1 except that the registered trademark) "CAF" was 20 parts by mass. This resin composition was excellent in handleability at room temperature without being deformed even when lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had almost no unimpregnated portion on the surface or voids inside, and was excellent in impregnation property. Further, as a result of Tg measurement, a sufficiently uniform fiber-reinforced composite material was obtained, although some unevenness was observed depending on the position.

(Example 6)
As shown in Table 1, the components [B] used were 23 parts by mass of 4,4'-diaminodiphenyl sulfone "Seikacure S" and 22 parts by mass of 4,4'-isopropyridene diphenol "bisphenol A". Except for the above, an epoxy resin composition was prepared in the same manner as in Example 1. This resin composition was excellent in handleability at room temperature without being deformed even when lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had almost no unimpregnated portion on the surface or voids inside, and was excellent in impregnation property. Further, as a result of Tg measurement, a sufficiently uniform fiber-reinforced composite material was obtained, although some unevenness was observed depending on the position.

(Example 7)
As shown in Table 1, the components [B] used were 32 parts by mass of 4,4'-diaminodiphenyl sulfone "Seikacure S" and 7 parts by mass of 4,4'-isopropyridene diphenol "bisphenol A". Except for the above, an epoxy resin composition was prepared in the same manner as in Example 1. This resin composition was excellent in handleability at room temperature without being deformed even when lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had sufficient impregnation property although some internal voids were observed on the surface. Further, as a result of Tg measurement, a sufficiently uniform fiber-reinforced composite material was obtained, although some unevenness was observed depending on the position.

(Example 8)
As shown in Table 1, the component [A] used is 100 parts by mass of the bisphenol F type epoxy resin "YSLV-80XY", and the component [B] used is 4,4'-diamino-3,3', 5, 5'-tetraethyldiphenylmethane "" Lonzacure (registered trademark) "M-DEA" 22 parts by mass and 1,2,3,6-tetrahydrophthalic anhydride "Ricacid" (registered trademark) TH "44 parts by mass, component [C ], An epoxy resin composition was prepared in the same manner as in Example 1 except that 5 parts by mass of triphenylphosphine "TPP" was blended. This resin composition had sufficient handleability at room temperature even when it was lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had sufficient impregnation property although some internal voids were observed on the surface. Further, as a result of Tg measurement, a sufficiently uniform fiber-reinforced composite material was obtained, although some unevenness was observed depending on the position.

(Example 9)
As shown in Table 1, the component [A] to be used is 100 parts by mass of the eutectic "" jER (registered trademark) "YL6121H" of the tetramethylbiphenyl type epoxy resin and the biphenyl type epoxy resin, and the component [B] to be used is used. An epoxy resin composition was prepared in the same manner as in Example 1 except that the amount was 35 parts by mass of 4,4'-diaminodiphenyl sulfone "Seikacure S". This resin composition was excellent in handleability at room temperature when lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had sufficient impregnation property although some internal voids were observed on the surface. Further, as a result of Tg measurement, a sufficiently uniform fiber-reinforced composite material was obtained, although some unevenness was observed depending on the position.

(Example 10)
As shown in Table 1, 100 parts by mass of the component [A] used is 100 parts by mass of the co-crystal "" jER (registered trademark) "YL6121H" of the tetramethylbiphenyl type epoxy resin and the biphenyl type epoxy resin, and the component [B] to be used is used. Epoxy resin in the same manner as in Example 1 except that 18 parts by mass of 4,4'-diaminodiphenyl sulfone "Seikacure S" and 18 parts by mass of 3,3'-diaminodiphenyl sulfone "3,3'-DAS" were used. The composition was prepared. This resin composition was excellent in handleability at room temperature even when it was lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had almost no unimpregnated portion on the surface or voids inside, and was excellent in impregnation property. In addition, as a result of Tg measurement, a uniform fiber-reinforced composite material was obtained with almost no unevenness depending on the position.

(Example 11)
As shown in Table 1, the component [A] used is 100 parts by mass of the isocyanuric acid type epoxy resin "TEPIC-S", and the component [B] used is 4,5'-diaminodiphenyl sulfone "Seikacure S" 31% by mass. An epoxy resin composition was prepared in the same manner as in Example 1 except for the portion and 31 parts by mass of 3,3'-diaminodiphenyl sulfone "3,3'-DAS". This resin composition was excellent in handleability at room temperature even when it was lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had almost no unimpregnated portion on the surface or voids inside, and was excellent in impregnation property. In addition, as a result of Tg measurement, a uniform fiber-reinforced composite material was obtained with almost no unevenness depending on the position.

(Example 12)
As shown in Table 1, the component [A] used is 70 parts by mass of the tetramethylbiphenyl type epoxy resin "" jER (registered trademark) "YX4000", and the other epoxy resin is the bisphenol A type epoxy resin "" jER (registered trademark) ". Trademark) "1001" 30 parts by mass, component [B] used is 14,4'-diaminodiphenyl sulfone "Seikacure S" 14 parts by mass and 3,3'-diaminodiphenyl sulfone "3,3'-DAS" 14 mass An epoxy resin composition was prepared in the same manner as in Example 1 except that the parts were used. This resin composition was excellent in handleability at room temperature even when it was lifted by hand. The fiber-reinforced composite material produced by using the preform composed of this resin composition and the dry-reinforced fiber base material had almost no unimpregnated portion on the surface or voids inside, and was excellent in impregnation property. Further, as a result of Tg measurement, a sufficiently uniform fiber-reinforced composite material was obtained, although some unevenness was observed depending on the position.

(Comparative Example 1)
As shown in Table 1, 17 parts by mass and 3 parts of 4,4'-diaminodiphenyl sulfone "Seikacure S" were formed into separate single crystals without lowering the melting point of the component [B] to be used by eutecticization in advance. , 3'-Diaminodiphenyl sulfone "3,3'-DAS" An epoxy resin composition was prepared in the same manner as in Example 1 except that the amount was 17 parts by mass. In this resin composition, the difference in melting point between the component [A] and the component [B] is too large, so that the impregnation property is poor when the fiber-reinforced composite material is used, and the composition unevenness also occurs.

(Comparative Example 2)
As shown in Table 1, the component [A] used is 100 parts by mass of the eutectic "" jER (registered trademark) "YL6121H" of the tetramethylbiphenyl type epoxy resin and the biphenyl type epoxy resin, and the component [B] is 9, An epoxy resin composition was prepared in the same manner as in Example 1 except that the amount of 9-bis (4-amino-3-chlorophenyl) fluorene "" Lonzacure (registered trademark) "CAF" was 59 parts by mass. In this resin composition, the difference in melting point between the component [A] and the component [B] is too large, so that the impregnation property is poor when the fiber-reinforced composite material is used, and the composition unevenness also occurs.

(Comparative Example 3)
As shown in Table 1, the epoxy resin composition is the same as in Example 1 except that the component [B] used is 33 parts by mass of a single 4,4'-diaminodiphenyl sulfone "Seikacure S". Was prepared. In this resin composition, the difference in melting point between the component [A] and the component [B] is too large, so that the impregnation property is poor when the fiber-reinforced composite material is used, and the composition unevenness also occurs.

Since the epoxy resin composition of the present invention is excellent in handleability at room temperature and resin impregnation property when it is used as a fiber-reinforced composite material, it is easier to obtain a high-quality fiber-reinforced composite material by a press molding method or the like. It can be provided with productivity. Therefore, the application of fiber-reinforced composite materials to automobiles and aircraft applications is progressing, and it is expected that further weight reduction of these materials will contribute to improvement of fuel efficiency and reduction of global warming gas emissions.

Claims

It contains a component [A] and a component [B], and also contains a component [b] as a component [B], and the difference in melting point between the component [A] and the component [B] is 0 to 60 ° C., and a crystalline component. An epoxy resin composition for a fiber-reinforced composite material containing 70% by mass or more.
Component [A]: Crystalline epoxy resin component [B]: Crystalline curing agent Component [b]: Crystalline curing agent composed of two or more kinds of crystalline monomer compounds and having a single melting point.
It contains a component [A] and a component [B], and also contains a component [a] as a component [A], and the difference in melting point between the component [A] and the component [B] is 0 to 60 ° C., and a crystalline component. An epoxy resin composition for a fiber-reinforced composite material containing 70% by mass or more.
Component [A]: Crystalline epoxy resin component [a]: Crystalline epoxy resin component [B]: a crystalline epoxy resin component [B]: which is composed of two or more kinds of crystalline monomer compounds and has a single melting point.
The epoxy resin composition for a fiber-reinforced composite material according to claim 1, wherein the melting point of the component [b] is lower than the melting point of each of the crystalline monomer compounds contained in the component [b].
The epoxy resin composition for a fiber-reinforced composite material according to any one of claims 1 to 3, wherein the component [A] contains a biphenyl type epoxy resin.
The epoxy resin composition for a fiber-reinforced composite material according to any one of claims 1 to 4, wherein the component [B] contains diaminodiphenyl sulfone.
A preform having the epoxy resin composition for a fiber-reinforced composite material according to any one of claims 1 to 5 and a dry-reinforced fiber base material.
A fiber-reinforced composite material obtained by impregnating and curing a dry-reinforced fiber base material with the epoxy resin composition for a fiber-reinforced composite material of the preform according to claim 6.