JP2023067809A - Epoxy resin composition, prepreg and fiber-reinforced composite material - Google Patents

Abstract

To provide an epoxy resin composition which can be cured at 130°C and can achieve heat resistance, flexural modulus and flexural strength at high level and to provide a prepreg comprising the epoxy resin composition and a fiber-reinforced composite material obtained by curing the prepreg.SOLUTION: There is provided an epoxy resin composition which comprises [A] a diaminodiphenylmethane-based epoxy resin, [B] a bisphenol type epoxy resin having an epoxy equivalent weight of 400 g/eq. or more and 1500 g/eq. or less, [C] 4,4'-diaminodiphenylsulfone, [D] dicyandiamide and [E] core-shell rubber particles and comprises 40 to 70 pts.mass of [A], 10 to 30 pts.mass of [B], 10 to 21 pts.mass of [C], 3 to 7 pts.mass of [D] and 5 to 10 pts.mass of [E] based on 100 pts.mass of the whole epoxy resin and satisfies the relation of 3.0≤(the content of [C]/the content of [D])≤4.0.SELECTED DRAWING: None

Description

The present invention relates to an epoxy resin composition preferably used as a matrix resin for fiber-reinforced composite materials suitable for sports applications, general industrial applications, and aerospace applications, and prepregs and fiber-reinforced composite materials using the same as the matrix resin. It is.

A sheet-like intermediate base material (prepreg) in which reinforcing fibers are impregnated with a thermosetting resin is widely used for the production of fiber-reinforced plastics. A molded article is obtained by laminating prepregs and heating to harden a thermosetting resin, which is applied to various fields such as aircraft and sports. As the thermosetting resin used as the matrix resin of the prepreg, an epoxy resin is widely used because of its excellent heat resistance, adhesiveness and mechanical strength. In recent years, as the application of fiber-reinforced composite materials has expanded, demands for further weight reduction and higher heat resistance of members have increased, and higher performance epoxy resins used in prepregs have been desired.

By increasing the breaking strength of cured epoxy resins, it becomes possible to design lightweight and high-performance fiber-reinforced composite materials. In order to increase the breaking strength of fiber-reinforced composite materials, methods of increasing the strength and elastic modulus of cured epoxy resins are generally known.

In addition, heat resistance of about 150° C. is required for applications that are expected to be used in high-temperature environments, such as structural members around the engine of automobiles and racing cars, and reinforcing materials for motors.

Furthermore, from the viewpoint of economic rationality in the production of fiber-reinforced composite materials, a technique for obtaining fiber-reinforced composite materials at a lower curing temperature is also required.

Patent Document 1 discloses a technique for achieving both heat resistance and elastic modulus in curing at 150° C. by using an amine-type epoxy resin, a bisphenol-type epoxy resin, diaminodiphenylsulfone, dicyandiamide, and a urea compound together. there is

In Patent Document 2, a trifunctional amine type epoxy resin, a bisphenol F type epoxy resin, 3,3'-diaminodiphenylsulfone, dicyandiamide, and aromatic urea are used in combination to obtain an epoxy resin cured product in curing at 130°C. A technique for achieving both the flexural modulus and flexural strength is disclosed.

Patent Document 3 discloses an isocyanuric acid type epoxy resin, a glycidylamine type epoxy resin,
A technique for achieving both heat resistance and mechanical properties at high temperatures by using dicyandiamide and diaminodiphenylsulfone in combination is disclosed.

JP-A-2010-53278 Japanese Patent Application Laid-Open No. 2020-204026 WO2017/047225

The epoxy resin composition described in Patent Document 1 lacks the flexural modulus and flexural strength of the cured resin, and the breaking strength of the fiber-reinforced composite material is insufficient. Moreover, a high temperature of 150° C. was required for curing.

The epoxy resin composition described in Patent Document 2 can be cured at 130° C. and exhibits a high flexural modulus and strength, but does not satisfy a high level of heat resistance.

The epoxy resin composition described in Patent Document 3 may not necessarily satisfy a high level of bending strength of the cured resin, and it is difficult to say that the breaking strength of the fiber-reinforced composite material also satisfies a high level. rice field. Moreover, a high temperature of 180° C. was required for curing.

The present invention overcomes the drawbacks of the prior art and provides an epoxy resin composition that can be cured at 130° C. and has high levels of both heat resistance, flexural modulus, and flexural strength, and the epoxy resin composition. and a fiber-reinforced composite material obtained by curing the prepreg.

As a result of intensive studies aimed at solving the above problems, the inventors of the present invention found an epoxy resin composition having the following constitution, and completed the present invention. That is, the epoxy resin composition of this invention consists of the following structures.
An epoxy resin composition containing the following components [A] to [E] and satisfying the following conditions (a) to (f).
[A] diaminodiphenylmethane-type epoxy resin [B] bisphenol-type epoxy resin having an epoxy equivalent of 400 g/eq to 1500 g/eq [C] 4,4′-diaminodiphenylsulfone [D] dicyandiamide [E] core-shell rubber particles (a ) Contains 40 to 70 parts by mass of component [A] out of 100 parts by mass of all epoxy resins (b) Contains 10 to 30 parts by mass of component [B] out of 100 parts by mass of all epoxy resins (c) All epoxy resins 10 to 21 parts by mass of component [C] per 100 parts by mass of (d) 3 to 7 parts by mass of component [D] per 100 parts by mass of total epoxy resin (e) per 100 parts by mass of total epoxy resin On the other hand, containing 5 to 10 parts by mass of component [E] (f) 3.0 ≤ (content of [C] / content of [D]) ≤ 4.0
Also, the prepreg of the present invention is a prepreg comprising the epoxy resin composition and reinforcing fibers.

Further, the fiber-reinforced composite material of the present invention is a fiber-reinforced composite material obtained by curing the prepreg.

According to the present invention, a resin cured product that exhibits a high elastic modulus and a high bending strength when cured at 130° C. and is also excellent in heat resistance is provided, and fiber reinforcement is performed using the epoxy resin composition of the present invention as a matrix resin. Composite materials can exhibit excellent mechanical properties.

The epoxy resin composition of the present invention comprises [A] a diaminodiphenylmethane type epoxy resin, [B] a bisphenol type epoxy resin having an epoxy equivalent of 400 g/eq or more and 1500 g/eq or less, [C] 4,4'-diaminodiphenyl sulfone, It contains [D] dicyandiamide and [E] core-shell rubber particles as essential components. First, these constituent elements will be described. In the present invention, "component" means a compound contained in the composition. Also, when the essential range, preferable range, etc. for a certain physical property, characteristic or composition ratio are indicated by multiple numerical ranges, the combination of any upper limit value and any lower limit value in the same multiple ranges is also within a preferable range (for example, a preferable range of 40 to 60 parts by mass for the amount of component [A] described below).

(Component [A])
Component [A] in the present invention is a diaminodiphenylmethane type epoxy resin.

As the diaminodiphenylmethane type epoxy resin, "Sumiepoxy (registered trademark)" ELM434, ELM434VL (manufactured by Sumitomo Chemical Co., Ltd.), YH434, YH434L (manufactured by Nippon Steel Chemical & Materials Co., Ltd.), "jER (registered trademark) )” 604 (manufactured by Mitsubishi Chemical Corporation), “Araldite (registered trademark)” MY720, MY721 (manufactured by Huntsman Advanced Materials) and the like can be used.

As the condition (a), the epoxy resin composition of the present invention must contain 40 to 70 parts by mass of component [A] out of 100 parts by mass of the total epoxy resin, preferably 45 to 65 parts by mass. Preferably, it is 50 to 60 parts by mass. By satisfying the above range, it is possible to obtain an epoxy resin cured product having a good balance between heat resistance and bending strength of the cured resin product. If component [A] is less than 40 parts by mass, the cured resin will have insufficient heat resistance and bending strength, and if it exceeds 70 parts by mass, the cured resin will have insufficient bending strength.

(Component [B])
Component [B] in the present invention is a bisphenol type epoxy resin having an epoxy equivalent of 400 g/eq to 1500 g/eq.

Commercial products of such bisphenol-type epoxy resins include "jER (registered trademark)" 1001, 1002, 1003, 1004, 4004P, 4005P (manufactured by Mitsubishi Chemical Corporation), and "Epotote (registered trademark)" YDF2001, YDF2004. (all of which are manufactured by Nippon Steel Chemical & Materials Co., Ltd.). Among them, bisphenol F type epoxy resin is preferable from the viewpoint of obtaining high bending strength.

Since the epoxy resin composition of the present invention contains a bisphenol type epoxy resin having an epoxy equivalent within the above range as the component [B], bending strain and bending strength are improved.

As the condition (b), the epoxy resin composition of the present invention must contain 10 to 30 parts by mass of component [B] out of 100 parts by mass of the total epoxy resin, preferably 12 to 28 parts by mass. It is preferably from 14 to 26 parts by mass, and more preferably from 14 to 26 parts by mass. By satisfying the above range, it is possible to obtain an epoxy resin cured product having a good balance between heat resistance and bending strength of the cured resin product. If component [A] is less than 10 parts by mass, bending strength will be insufficient, and if it is more than 30 parts by mass, bending strength and heat resistance of the cured resin will be insufficient.

The epoxy resin composition used in the present invention can contain other epoxy resins different from components [A] and [B] as long as the effects of the present invention are not lost.

Other epoxy resins include, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, aniline type epoxy resin, isocyanuric acid type epoxy resin, phenol novolak type epoxy resin, dicyclopentadiene type epoxy resin and the like. These may be used in combination of multiple types.

(Component [C])
Component [C] in the present invention is 4,4'-diaminodiphenylsulfone, which functions as a curing agent for epoxy resins. Diaminodiphenylsulfone has positional isomers with different amino group positions. In the present invention, it is necessary to use 4,4'-diaminodiphenylsulfone having an amino group at the para-position to the sulfonyl group from the viewpoint of the balance between heat resistance and bending strength.

As the condition (c), the epoxy resin composition of the present invention must contain 10 to 21 parts by mass of component [C] per 100 parts by mass of the total epoxy resin, preferably 20 parts by mass or less. , more preferably 11 to 19 parts by mass, more preferably 12 to 18 parts by mass.

Moreover, in the present invention, as will be described later, component [C] must be used in combination with component [D] in a predetermined ratio.

(Component [D])
Component [D] in the present invention is dicyandiamide, which functions as a curing agent for epoxy resins.

Commercial products of such dicyandiamide include DICY7 and DICY15 (manufactured by Mitsubishi Chemical Corporation).

As the condition (d), the epoxy resin composition of the present invention must contain 3 to 7 parts by mass, preferably 4 to 6 parts by mass, of component [D] with respect to 100 parts by mass of the total epoxy resin. preferable.

In the present invention, by using both components [C] and [D] as curing agents, an epoxy resin composition having excellent bending strength and capable of being cured at a low temperature of 130° C. can be obtained.

In the present invention, the content of component [C] and component [D] in the epoxy resin composition must satisfy the following condition (f) as a mass ratio.

Condition (f) 3.0 ≤ ([C] content/[D] content) ≤ 4.0
Regarding condition (f), as described above, if the value indicated by the ratio of the content of [C] to the content of [D] is in the range of 3.0 or more and 4.0 or less, cure at 130 ° C. for 90 minutes It is possible to achieve both bending strength and heat resistance of the resin cured product obtained by curing at a high level. If the value indicated by [C] content/[D] content is less than 3.0, both bending strength and heat resistance of the cured resin are insufficient. , the bending strength becomes insufficient.

(Component [E])
Component [E] in the present invention is core-shell rubber particles. By using the component [E] together with the components [A] to [D], it is possible to obtain a cured epoxy resin product having a good balance between the heat resistance and the bending strength of the cured resin product.

First, rubber particles are particles having rubber elasticity. Core-shell rubber particles are a type of rubber particles, and are particles in which the surface of a particulate core component is modified with a shell component, and a part or the entire surface of the core component is coated with the shell component. Generally, the core component is rubber. By coating with the shell component, dispersibility in the epoxy resin composition becomes better than that of rubber particles, thereby making it easier to obtain a cured epoxy resin product with higher fracture toughness. The components of the core component and the shell component are not particularly limited as long as they have the core and shell components.

Examples of core components include butadiene rubber, acrylic rubber, silicone rubber, butyl rubber, NBR, SBR, IR and EPR.

The shell component includes, for example, a polymer obtained by polymerizing a monomer selected from acrylic acid ester-based monomers, methacrylic acid ester-based monomers, aromatic vinyl monomers, and the like.

Products containing such component [E] include "Kane Ace" (registered trademark) (MX-125, MX-150, MX-154, MX-257, MX-267, MX-416, MX-451, MX-EXP (HM5) (manufactured by Kaneka Corporation), "PARALOID (registered trademark)" EXL-2655, EXL-2668 (manufactured by Dow Chemical), etc. Among these, epoxy resins can be used. There are also products in the state of so-called masterbatch that are pre-dispersed therein.

As condition (e), the epoxy resin composition of the present invention must contain component [E] in an amount of 5 to 10 parts by mass based on 100 parts by mass of the total epoxy resin. By satisfying the above range, it is possible to obtain an epoxy resin cured product having a good balance between heat resistance and bending strength of the cured resin product. If component [E] is less than 5 parts by mass with respect to 100 parts by mass of the total epoxy resin, the cured resin will have insufficient bending strength, and if it exceeds 10 parts by mass, the cured resin will also have insufficient bending strength.
(Component [F])
The epoxy resin composition of the present invention preferably contains a curing accelerator as component [F] in order to shorten the curing time.

Examples of such component [F] include 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 4,4′-methylenebisphenyldimethylurea. , phenyldimethylurea, toluenebisdimethylurea, and the like.

Commercially available products of component [F] include DCMU99 (manufactured by Hodogaya Chemical Industry Co., Ltd.), “Omicure (registered trademark)” U-24 (manufactured by PTI Japan Co., Ltd.), “Dyhard (registered Trademark) UR505 (manufactured by CVC).

(Component [G])
The epoxy resin composition of the present invention uses a thermoplastic resin as the component [G] for the purpose of adjusting the viscoelasticity, improving the tack and drape properties of the prepreg, and improving the mechanical properties and toughness of the resin composition. can be used. Examples of such thermoplastic resins include polyvinyl acetal resins such as polyvinyl formal and polyvinyl butyral, polyvinyl alcohol, phenoxy resins, polyamides, polyimides, polyvinylpyrrolidone, and polyether sulfones.

For the preparation of the epoxy resin composition of the present invention, kneading may be carried out using a machine such as a kneader, planetary mixer, three-roll and twin-screw extruder. You can mix by hand using a spatula or the like.

The prepreg of the present invention can be obtained by impregnating a reinforcing fiber base material with the epoxy resin composition prepared by the method described above. As a method for impregnation, a hot melt method (dry method) or the like can be used. The hot-melt method is a method in which a thermosetting resin composition whose viscosity has been reduced by heating is directly impregnated into reinforcing fibers, or a film is prepared by coating an epoxy resin composition on release paper or the like, and then reinforcing fibers This is a method of impregnating the reinforcing fibers with a resin by stacking this film from both sides or one side of the fiber and applying pressure and heat. At this time, the fiber mass content of the prepreg can be adjusted by changing the amount of resin applied to the release paper.

The reinforcing fibers used in the present invention are not particularly limited, and glass fibers, carbon fibers, aramid fibers, boron fibers, alumina fibers, silicon carbide fibers and the like can be used. Two or more kinds of these fibers may be mixed and used. It is preferable to use carbon fiber from the viewpoint of obtaining a lightweight and highly rigid fiber-reinforced composite material.

In the prepreg lamination molding method, a press molding method, an autoclave molding method, a bagging molding method, a wrapping tape method, an internal pressure molding method, or the like can be appropriately used as a method of applying heat and pressure.

A resin cured product of the epoxy resin composition of the present invention and a fiber-reinforced composite material containing reinforcing fibers are preferably used for sports applications, aerospace applications and general industrial applications. More specifically, in sports applications, it is preferably used for golf shafts, fishing rods, tennis and badminton rackets, and the like. In aerospace applications, it is preferably used for aircraft primary structural materials such as main wings, tail wings and floor beams, and secondary structural materials such as interior materials. Furthermore, in general industrial applications, it is preferably used for structural materials such as automobiles, bicycles, ships and railway vehicles. In particular, from the viewpoint of achieving both heat resistance of 150 ° C. or higher and mechanical properties, it is preferable for applications that are assumed to be used in high temperature environments, such as structural members around the engine of automobiles and racing cars, and reinforcing materials for motors. Used.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the description of these examples.

The components used in this embodiment are as follows.

<Materials used>
• Component [A]: diaminodiphenylmethane type epoxy resin • "Sumiepoxy (registered trademark)" ELM434 (manufactured by Sumitomo Chemical Co., Ltd.).

・ Component [B]: bisphenol type epoxy resin with an epoxy equivalent of 400 g / eq or more and 1500 g / eq or less ・ “Epotato (registered trademark)” YDF2001 (bisphenol F type epoxy resin with an epoxy equivalent of 485 g / eq, Nippon Steel Chemical & Materials Co., Ltd. ) made)
- "jER (registered trademark)" 4005P (bisphenol F type epoxy resin having an epoxy equivalent of 1075 g/eq, manufactured by Mitsubishi Chemical Corporation).

・ Other epoxy resins ・ “jER (registered trademark)” 828, (bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation)
· "jER (registered trademark)" 4007P (bisphenol F type epoxy resin with an epoxy equivalent of 2250 g / eq, manufactured by Mitsubishi Chemical Corporation)
- "Araldite (registered trademark)" MY0600 (aminophenol-type epoxy resin, manufactured by Huntsman Advanced Materials).

• Component [C]: 4,4'-diaminodiphenylsulfone "Seikacure (registered trademark)"-S (manufactured by Wakayama Seika Kogyo Co., Ltd.).

- Component [D]: dicyandiamide DICY7 (manufactured by Mitsubishi Chemical Corporation).

・Other curing agents ・3,3′-DAS (3,3′-diaminodiphenylsulfone, manufactured by Mitsui Chemicals Fine Co., Ltd.)
Component [E]: Core shell rubber particles ・"Kane Ace" (registered trademark) MX-EXP (HM5) (70% by mass of bisphenol A type epoxy resin as other epoxy resins other than components [A] and [B], and component A masterbatch containing 30% by mass of core-shell type rubber particles as [E]).

• Component [F]: curing accelerator • "Omicure (registered trademark)" 24 (toluenebisdimethylurea, manufactured by PTI Japan Co., Ltd.).

• Component [G] Thermoplastic resin • "Vinylec (registered trademark)" K (polyvinyl formal, manufactured by JNC Corporation).

<Method for preparing epoxy resin composition>
Into a stainless steel beaker, component [C] 4,4'-diaminodiphenylsulfone, component [D] dicyandiamide, [F] curing accelerator, and other components other than the curing agent are placed in predetermined amounts, heated to 150°C, and each After appropriately kneading until the components were mutually dissolved, the temperature was lowered to 60°C.

Separately, predetermined amounts of "Sumiepoxy (registered trademark)" ELM434 and [D]dicyandiamide were added to a polyethylene cup, and the mixture was passed through rolls twice using a three-roll mill to prepare a dicyandiamide master. The main component (epoxy resin) prepared above and the dicyandiamide master are kneaded at 60°C so as to have a predetermined content ratio, and finally component [C], component [F] curing accelerator, and other curing agents are added in predetermined amounts. After the addition, the epoxy resin composition was obtained by kneading at 60° C. for 30 minutes. The composition of the epoxy resin composition in each example is as shown in the table.

<Method for evaluating bending properties of cured epoxy resin>
After defoaming the uncured resin composition in a vacuum, it is cured at a temperature of 130° C. for 90 minutes in a mold set to a thickness of 2 mm with a 2 mm thick “Teflon (registered trademark)” spacer, A plate-like epoxy resin cured product having a thickness of 2 mm was obtained. A test piece having a width of 10 mm and a length of 60 mm was cut out from this resin cured product, and an Instron universal testing machine (manufactured by Instron) was used to set the span to 32 mm and the crosshead speed to 2.5 mm/min. 1994), flexural modulus, flexural strength and flexural strain were measured. At this time, the values measured with the number of samples n=6 were adopted as the values of the flexural modulus and the flexural strength.

<Method for evaluating glass transition temperature of cured epoxy resin>
After defoaming the uncured resin composition in a vacuum, it was cured at a temperature of 130°C in a mold set so that the thickness of the resulting cured product was 2 mm with a 2 mm thick “Teflon (registered trademark)” spacer. After curing for 90 minutes, a plate-like epoxy resin cured product having a thickness of 2 mm was obtained. According to JIS K7095 (2018), a test piece with a width of 12.7 mm and a length of 45 mm was cut out from this epoxy resin cured product, and a dynamic viscoelasticity measuring device (ARES W / FCO: manufactured by TA Instruments) was used. A test piece was set on a solid torsion jig, and dynamic viscoelasticity was measured in a temperature range of 40 to 260°C at a heating rate of 5°C/min, a frequency of 1Hz, and a strain of 0.08%. At this time, the glass transition temperature was defined as the temperature at the intersection of the tangent line drawn to the glass state region and the tangent line drawn to the glass transition temperature region in the obtained graph of storage modulus and temperature. For this evaluation, the number of samples n=1 was measured.

(Example 1)
As epoxy resins, 55 parts by mass of "Sumiepoxy (registered trademark)" ELM434, 25 parts by mass of "Epototo (registered trademark)" YDF2001, 4.6 parts by mass of "jER (registered trademark)" 828, "Kane Ace" (registered trademark) ) 22 parts by mass of MX-EXP (HM5) (including 6.6 parts by mass of component [E] and 15.4 parts by mass of other epoxy resins); 15 parts by mass of "-S", 4.3 parts by mass of DICY7 as dicyandiamide, 2 parts by mass of "Omicure (registered trademark)" U-24 as a curing accelerator, and "Vinylec (registered trademark)" as a thermoplastic resin. Using 6 parts by mass of K, an epoxy resin composition was prepared according to the <Method for preparing epoxy resin composition>.

This epoxy resin composition was cured at 130° C. for 90 minutes to obtain the flexural properties of the cured epoxy resin composition according to <Method for evaluating flexural properties of cured epoxy resin material>. The strength was 186 MPa. Further, the glass transition temperature measured according to <Evaluation method of glass transition temperature of epoxy resin cured product> was 157°C.

(Examples 2-7)
An epoxy resin composition and a resin cured product were produced in the same manner as in Example 1, except that the resin composition was changed as shown in Table 1. In addition, all the units of the numerical value regarding a resin composition are a mass part.

As a result of evaluating the bending properties and the glass transition temperature of the epoxy resin composition of each example, good physical properties were obtained at all levels.

(Comparative Examples 1 to 12)
An epoxy resin composition and a resin cured product were produced and evaluated in the same manner as in Example 1, except that the resin compositions were changed as shown in Tables 2 and 3, respectively. In addition, all the units of the numerical value regarding a resin composition are a mass part. The resin bending properties and heat resistance of each comparative example were as follows.

(Comparative example 1)
The bending elastic modulus was 3.7 GPa, the bending strength was 153 MPa, and the glass transition temperature was 132°C. Since the content of component [A] was small and the content of component [B] was large, the bending elastic modulus, bending strength and glass transition temperature were low.

(Comparative example 2)
The bending elastic modulus was 4.1 GPa, the bending strength was 151 MPa, and the glass transition temperature was 160°C. Since the component [A] was large and the component [B] was small, the bending strength was low.

(Comparative Example 3)
The bending elastic modulus was 4.0 GPa, the bending strength was 155 MPa, and the glass transition temperature was 145°C. Since the value of [C] content/[D] content was smaller than 2.8 and 3.0, the bending strength and the glass transition temperature were low.

(Comparative Example 4)
The bending elastic modulus was 4.0 GPa, the bending strength was 157 MPa, and the glass transition temperature was 155°C. Since the value of [C] content/[D] content was greater than 4.2 and 4.0, the bending strength was low.

(Comparative Example 5)
The bending elastic modulus was 4.1 GPa, the bending strength was 165 MPa, and the glass transition temperature was 153°C. Since the contents of component [C] and component [D] were small, the bending strength was low.

(Comparative Example 6)
The bending elastic modulus was 3.9 GPa, the bending strength was 151 MPa, and the glass transition temperature was 158°C. Since the contents of component [C] and component [D] were large, the flexural modulus and flexural strength were low.

(Comparative Example 7)
The bending elastic modulus was 4.2 GPa, the bending strength was 168 MPa, and the glass transition temperature was 160°C. Since it did not contain core-shell rubber particles, it had low bending strength.

(Comparative Example 8)
The bending elastic modulus was 4.1 GPa, the bending strength was 165 MPa, and the glass transition temperature was 158°C. Since the content of core-shell rubber particles was small, the bending strength was low.

(Comparative Example 9)
The bending elastic modulus was 3.8 GPa, the bending strength was 168 MPa, and the glass transition temperature was 153°C. Since the content of core-shell rubber particles was large, the flexural modulus and flexural strength were low.

(Comparative Example 10)
The bending elastic modulus was 4.8 GPa, the bending strength was 210 MPa, and the glass transition temperature was 132°C. Although the flexural modulus and flexural strength were extremely high, the glass transition temperature was low.

(Comparative Example 11)
The bending elastic modulus was 4.6 GPa, the bending strength was 195 MPa, and the glass transition temperature was 130°C. Although the flexural modulus and flexural strength were extremely high, the glass transition temperature was low. Incidentally, Comparative Example 11 is positioned as a mixture of the core-shell rubber particles in Comparative Example 10, but in this composition, the effect of improving the bending strength due to the incorporation of the core-shell rubber particles was not observed.

(Comparative Example 12)
Comparative Example 12 uses a bisphenol F-type epoxy resin with a large epoxy equivalent instead of component [B], and has a bending elastic modulus of 3.8 GPa, a bending strength of 170 MPa, and a glass transition temperature of 140°C. Yes, and both were low.

(Comparative Example 13)
For the resin composition shown in Table 3, an epoxy resin composition and a cured resin were produced in the same manner as in Example 1, except that the component [D] dicyandiamide was not blended. Since the component [D] was not included, the cured resin obtained by curing at 130° C. for 90 minutes did not proceed sufficiently with the curing reaction, and physical properties of the cured resin could not be obtained.

In addition, the unit of each component in the table is parts by mass.

Since the epoxy resin composition of the present invention gives a cured product having high levels of elastic modulus, bending strength and heat resistance when cured at 130° C., the fiber-reinforced composite material using the epoxy resin composition has mechanical properties. and excellent heat resistance. Therefore, it is possible to reduce the weight of the fiber-reinforced composite material, and it can be widely used for sports, general industrial applications, aerospace applications, and the like. In particular, since it has both heat resistance of 150°C or higher and mechanical properties, it is particularly preferable for applications that are expected to be used in high-temperature environments, such as structural members around the engine of automobiles and racing cars, and reinforcing materials for motors. Used.

Claims (4)

An epoxy resin composition containing the following components [A] to [E] and satisfying the following conditions (a) to (f).
[A] diaminodiphenylmethane-type epoxy resin [B] bisphenol-type epoxy resin having an epoxy equivalent of 400 g/eq to 1500 g/eq [C] 4,4′-diaminodiphenylsulfone [D] dicyandiamide [E] core-shell rubber particles (a ) Contains 40 to 70 parts by mass of component [A] out of 100 parts by mass of all epoxy resins (b) Contains 10 to 30 parts by mass of component [B] out of 100 parts by mass of all epoxy resins (c) All epoxy resins 10 to 21 parts by mass of component [C] per 100 parts by mass of (d) 3 to 7 parts by mass of component [D] per 100 parts by mass of total epoxy resin (e) per 100 parts by mass of total epoxy resin On the other hand, containing 5 to 10 parts by mass of component [E] (f) 3.0 ≤ (content of [C] / content of [D]) ≤ 4.0 A prepreg comprising the epoxy resin composition according to claim 1 and reinforcing fibers. The prepreg according to claim 2, wherein the reinforcing fibers are carbon fibers. A fiber-reinforced composite material obtained by curing the prepreg according to claim 2 or 3.