JP2020132733A - Epoxy resin composition for carbon fiber-reinforced composite material, prepreg, and carbon fiber-reinforced composite material - Google Patents

Abstract

To provide an epoxy resin composition for a carbon fiber-reinforced composite material which can obtain a carbon fiber-reinforced composite material having excellent mechanical characteristics and moist heat resistance and is excellent in molding and curing characteristics, a prepreg, and a carbon fiber-reinforced composite material.SOLUTION: There is provided an epoxy resin composition for a carbon fiber-reinforced composite material comprising: component (A): an epoxy resin; component (B): a thermoplastic resin; component (C): diaminodiphenyl sulfone; and component (D): dicyandiamide, in which the content of the component (B) is 5 to 25 pts.mass with respect to 100 pts.mass of the component (A). Assuming that the viscosity measured by a specific measuring method is expressed as η(T), temperature T is within a range of 65 to 100°C, and at any temperature within a range of 65 to 100°C, the epoxy resin composition for the carbon fiber-reinforced composite material satisfies the following formula (1). There are also provided a prepreg using the epoxy resin composition for the carbon fiber-reinforced composite material, and a carbon fiber-reinforced composite material. 5000exp(-0.08T)≤η(T)...expression (1)SELECTED DRAWING: None

Description

The present invention relates to epoxy resin compositions for carbon fiber reinforced composites, prepregs and carbon fiber reinforced composites.

Since the carbon fiber reinforced composite material is lightweight, high strength and high rigidity, it is widely used in the sports / leisure field, the automobile field, the aircraft field, other general industrial fields and the like. Recently, carbon fiber reinforced composite materials, which are lighter, stronger and more rigid, are often used in the fields of automobiles, aircraft and the like.

The carbon fiber reinforced composite material is a material containing carbon fiber and a matrix resin as essential components. As the matrix resin, a thermosetting resin composition or a thermoplastic resin composition is used, but the thermosetting resin composition is widely used as compared with the thermoplastic resin composition.

The carbon fiber reinforced composite material is manufactured by autoclave molding, press molding, internal pressure molding, etc. when a carbon fiber base material called prepreg is impregnated with a matrix resin, and filament winding molding when not via prepreg. Manufactured by Resin Transfer Molding (RTM) molding or the like. In the field of aircraft, etc., where high-quality carbon fiber reinforced composite materials are required, autoclave molding via prepreg is common.

When a carbon fiber reinforced composite material is produced from a prepreg in which a carbon fiber base material is impregnated with a thermosetting resin composition, a step of heating a laminate of prepregs to cure the thermosetting resin composition is required. When the laminate of prepreg is heated, the viscosity of the thermosetting resin composition decreases as the temperature rises until the curing reaction of the thermosetting resin composition starts, and a large amount of the thermosetting resin composition flows out of the system. It may end up. As a result, the dimensions of the carbon fiber reinforced composite material may differ from the desired dimensions, or the mechanical properties of the carbon fiber reinforced composite material may deteriorate. For this reason, it is important to control the outflow of the resin to the outside of the system (hereinafter, also referred to as “resin flow”) until curing. In addition to resin flow, carbon fiber reinforced composite materials are also required to have excellent mechanical properties and moisture and heat resistance in the aircraft field and the like.

The following are proposed as prepregs in which the resin flow is controlled and suppressed, for example.
(1) A prepreg in which the flow of a thermosetting resin composition is suppressed by adding a rocking agent (Patent Documents 1 and 2).
(2) A prepreg in which the minimum viscosity of a thermosetting resin composition at the time of molding is improved by adding a phenoxy resin (Patent Document 3).

Japanese Unexamined Patent Publication No. 2000-273224 Japanese Unexamined Patent Publication No. 2000-86784 Japanese Unexamined Patent Publication No. 7-118414

However, in the case of the prepreg of (1), the toughness of the cured product of the thermosetting resin composition is greatly reduced by adding the rocking agent. Since the toughness of the cured product of the thermosetting resin composition affects the mechanical properties of the carbon fiber reinforced composite material, particularly the interlayer fracture toughness value, it is difficult to use it in the aircraft field and the like.
In the case of the prepreg of (2), the addition of the phenoxy resin greatly reduces the moist heat resistance of the thermosetting resin composition. Therefore, it is difficult to use it in the aircraft field, etc., where high moisture and heat resistance is required. Further, it is not always easy to control the resin flow because the suitable blending amount of the phenoxy resin varies greatly depending on the type and blending amount of the epoxy resin and the type and blending amount of the curing agent.

An object of the present invention is to obtain a carbon fiber reinforced composite material having excellent mechanical properties and moisture heat resistance, and an epoxy resin composition for a carbon fiber reinforced composite material having excellent molding and curing properties, a prepreg, and a carbon fiber reinforced composite material. Is to provide.

The present invention has the following aspects.
[1] An epoxy resin composition for a carbon fiber reinforced composite material, which comprises the following components (A), components (B), components (C) and components (D).
The content of the following component (B) is 5 to 25 parts by mass with respect to 100 parts by mass of the following component (A).
When the viscosity measured by the following measuring method of the epoxy resin composition for carbon fiber reinforced composite material at the temperature T is η (T), the temperature T is in the range of 65 to 100 ° C., and is 65 to 100. An epoxy resin composition for a carbon fiber reinforced composite material in which η (T) satisfies the following formula (1) at any temperature within the range of ° C.
Component (A): Epoxy resin Component (B): Thermoplastic resin Component (C): Diaminodiphenyl sulfone Component (D): Dicyanodiamide 5000exp (-0.08T) ≤ η (T) ... 1)
<Measurement method>
The rheometer plate is preheated to 30 ° C., waits until the temperature stabilizes, and after confirming that the temperature has stabilized, the epoxy resin composition is separated into the plate, the gap is adjusted, and then the following measurement conditions are applied. Measure the viscosity of the epoxy resin composition with.
(Measurement condition)
・ Equipment: Rheometer ・ Plate used: 35φ parallel plate ・ Plate gap: 0.5mm
-Measurement mode: constant stress-Measurement frequency: 10 rad / sec-Rising rate: From 30 ° C. to at least the temperature immediately before the epoxy resin composition starts the curing reaction, the temperature is raised at 2 ° C./min.
・ Stress: 300Pa
[2] The carbon fiber of [1], wherein the temperature T is in the range of 65 to 100 ° C., and the η (T) satisfies the following formula (2) at any temperature in the range of 65 to 100 ° C. Epoxy resin composition for reinforced composite materials.
η (T) ≤30000 exp (-0.08T) ... Equation (2)
[3] The content of the component (C) is such that the active hydrogen group of the component (C) is 0.8 to 1.2 equivalents with respect to the epoxy group of the component (A). And the content of the component (D) is such that the active hydrogen group of the component (D) is 0.05 to 0.15 equivalent with respect to the epoxy group of the component (A). The epoxy resin composition for a carbon fiber reinforced composite material according to [1] or [2].
[4] The content of the component (C) is such that the active hydrogen group of the component (C) is 0.2 to 0.6 equivalent to the epoxy group of the component (A). And the content of the component (D) is such that the active hydrogen group of the component (D) is 0.2 to 0.5 equivalent with respect to the epoxy group of the component (A). The epoxy resin composition for a carbon fiber reinforced composite material according to [1] or [2].
[5] The epoxy resin composition for a carbon fiber reinforced composite material according to any one of [1] to [4], wherein the component (B) is a polyether sulfone.
[6] An epoxy resin composition for a carbon fiber reinforced composite material according to any one of [1] to [5], further comprising the following component (E).
Component (E): Curing Accelerator [7] The epoxy resin composition for a carbon fiber-reinforced composite material according to [6], wherein the component (E) is a urea compound.
[8] A prepreg in which the carbon fiber base material is impregnated with the epoxy resin composition for a carbon fiber reinforced composite material according to any one of [1] to [7].
[9] A carbon fiber reinforced composite material obtained by curing the prepreg of [8].

According to the present invention, a carbon fiber reinforced composite material having excellent mechanical properties and moisture heat resistance can be obtained, and an epoxy resin composition for a carbon fiber reinforced composite material having excellent molding and curing properties, a prepreg, and a carbon fiber reinforced composite material. Can be provided.

It is a figure which shows an example of the bagged prepreg laminated body schematically, (a) is a sectional view, and (b) is a plan view. It is a graph which shows the result of the temperature rise viscosity measurement in Examples 1 and 2 and Comparative Examples 1 and 2.

Hereinafter, the epoxy resin composition for carbon fiber reinforced composite material, the prepreg, and the carbon fiber reinforced composite material according to the embodiment of the present invention, and the manufacturing method thereof will be described in more detail.
The definitions of the following terms apply throughout the specification and claims.
-"Prepreg" is an intermediate material for producing a carbon fiber reinforced composite material in which a carbon fiber base material is impregnated with a resin composition such as an epoxy resin composition.
-The "carbon fiber reinforced composite material" includes a matrix resin and a carbon fiber base material. The carbon fiber reinforced composite material can be produced directly from the thermosetting resin composition or the thermoplastic resin composition as the matrix resin and the carbon fiber base material, or is produced through an intermediate material such as a prepreg. You can also do it. For example, a carbon fiber reinforced composite material can be obtained by laminating and curing a plurality of prepregs containing a thermosetting resin composition such as an epoxy resin as a matrix resin.
-The "epoxy resin composition for carbon fiber reinforced composite material" is an epoxy resin composition that can be suitably used as a matrix resin for carbon fiber reinforced composite material.
-"Epoxy resin" means a compound having two or more epoxy groups in the molecule.
"Epoxy equivalent" means the number of grams of epoxy resin containing 1 gram equivalent of epoxy groups.

[Epoxy resin composition for carbon fiber reinforced composite material]
The epoxy resin composition for a carbon fiber reinforced composite material of the present invention (hereinafter, also simply referred to as “epoxy resin composition”) has the following constituent elements (A), constituent elements (B), constituent elements (C) and constituent elements. (D) is included. The epoxy resin composition preferably further contains the following component (E). In addition, the epoxy resin composition may contain the following optional components, if necessary. The component (C) and the component (D) are hardeners.

<Component (A)>
The component (A) is an epoxy resin.
As the component (A), any epoxy resin can be used as long as it is an epoxy resin. Specifically, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, an epoxy resin having an oxazolidone ring skeleton, and a novolak type epoxy. Resin, triglycidylaminophenol, tetraglycidyldiaminodiphenylmethane, hydrophthalic acid type epoxy resin, bisphenol S type epoxy resin, resorcin type epoxy resin, hydroquinone type epoxy resin, bisphenoloxyethanol fluorene type epoxy resin, bisphenol fluorene type epoxy resin, bisphenol fluorene Examples include type epoxy resins. Among these, bisphenol A type epoxy resin liquid at 25 ° C, bisphenol F type epoxy resin liquid at 25 ° C, epoxy resin having an oxazolidone ring skeleton, novolac type epoxy resin, triglycidylaminophenol, tetraglycidyldiaminodiphenylmethane are selected. One or more epoxy resins are preferred. In particular, by combining a plurality of these epoxy resins, it is possible to obtain a prepreg having excellent handleability and more controllable resin flow during molding, and a carbon fiber reinforced composite material having excellent mechanical properties and heat resistance. ..

Specifically, as the composition of the component (A), at least of the bisphenol A type epoxy resin liquid at 25 ° C. and the bisphenol F type epoxy resin liquid at 25 ° C. with respect to the total mass of the component (A). One is 10 to 60% by mass, at least one of triglycidylaminophenol and tetraglycidyldiaminodiphenylmethane is 15 to 50% by mass, the novolak type epoxy resin is 0 to 30% by mass, and the epoxy has an oxazolidone ring skeleton. The resin is preferably 0 to 30% by mass, and at least one of the bisphenol A type epoxy resin liquid at 25 ° C. and the bisphenol F type epoxy resin liquid at 25 ° C. is 30 to 60% by mass, and triglycidyl aminophenol. More preferably, at least one of tetraglycidyldiaminodiphenylmethane is 20 to 40% by mass, the novolak type epoxy resin is 0 to 20% by mass, and the epoxy resin having an oxazolidone ring skeleton is 10 to 20% by mass.

Examples of commercially available bisphenol A type epoxy resins liquid at 25 ° C. include jER® 828 manufactured by Mitsubishi Chemical Corporation and D.D. E. R. (Registered trademark) 331; Epotote (registered trademark) YD-128 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd .; EPICLON (registered trademark) 850 manufactured by DIC Corporation and the like.
Commercially available products of the bisphenol F type epoxy resin liquid at 25 ° C. include, for example, jER (registered trademark) 806 and 807 manufactured by Mitsubishi Chemical Corporation; and D.D. E. R. (Registered trademark) 354; Epotote (registered trademark) YD-170 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd .; EPICLON (registered trademark) 830 manufactured by DIC and the like.
Examples of commercially available products of triglycidyl aminophenol include Araldite (registered trademark) MY0500, MY0510, MY0600, MY0610 manufactured by HUNTSMAN; and jER (registered trademark) 630 manufactured by Mitsubishi Chemical Corporation.
Examples of commercially available products of tetraglycidyl diaminodiphenylmethane include jER (registered trademark) 604 manufactured by Mitsubishi Chemical Corporation; Araldite (registered trademark) MY720 manufactured by HUNTSMAN; and YH434L manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.
Examples of commercially available epoxy resins having an oxazolidone ring skeleton include YD-952 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd .; EPICLON (registered trademark) TSR-400 manufactured by DIC Corporation.
Examples of commercially available novolak type epoxy resins include jER (registered trademark) 152, 154 manufactured by Mitsubishi Chemical Corporation; EPICLON (registered trademark) N740 and N775 manufactured by DIC Corporation.

<Component (B)>
The component (B) is a thermoplastic resin.
The thermoplastic resin is dissolved in the component (A), and does not retain the shape before dissolution such as the particle shape in the epoxy resin composition of the present invention.

Specific examples of the component (B) include polyether sulfone, polyetherimide, polyvinylformal, acrylic resin, and phenoxy resin. Among these, the polyether sulfone is blended with the epoxy resin composition to more appropriately suppress the fluidity of the epoxy resin composition when heated, and the cured product of the epoxy resin composition (hereinafter, "resin"). It is also preferable because it does not easily affect the mechanical properties and moisture and heat resistance of "cured product").
Examples of commercially available products of polyether sulfone include Sumika Excel PES5003MP and 2603MP manufactured by Sumitomo Chemical Co., Ltd .; Volkswagen® VW-10200RP and VW-10700RP manufactured by Solvay Co., Ltd .; Ultrason (registered trademark) E2020P manufactured by BASF Co., Ltd. Can be mentioned.

The content of the component (B) is 5 to 25 parts by mass, preferably 8 to 20 parts by mass, and more preferably 10 to 15 parts by mass with respect to 100 parts by mass of the component (A). When the content of the component (B) is 5 parts by mass or more, the fluidity of the epoxy resin composition when heated can be appropriately suppressed. When the content of the component (B) is 25 parts by mass or less, the viscosity of the epoxy resin composition does not become too high, and the carbon fiber base material can be sufficiently impregnated with the epoxy resin composition during the production of the prepreg. , It is possible to suppress defects such as voids when the carbon fiber reinforced composite material is used.

<Component (C)>
The component (C) is diaminodiphenyl sulfone, which is the first curing agent.
As the component (C), any isomer such as 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone and the like can be used.
One of these isomers may be used alone, or two or more thereof may be used in combination. However, if two or more isomers are used in combination, they may melt at a low temperature and the curing reaction may start at an unintended temperature. Therefore, it is preferable to use one isomer alone.
Commercially available products of diaminodiphenyl sulfone include, for example, SEIKACURE-S manufactured by Wakayama Seika Kogyo Co., Ltd .; 3,3'-DAS manufactured by Konishi Chemical Industry Co., Ltd .; Aradur (registered trademark) 9664-1, 9719-1 manufactured by HUNTSMAN. And so on.

<Component (D)>
The component (D) is dicyandiamide, which is a second curing agent.
Examples of commercially available dicyandiamides include jER Cure (registered trademark) DICY7 and DICY15 manufactured by Mitsubishi Chemical Corporation; DICYANEX (registered trademark) 1400F manufactured by Evonik Industries.

When the component (C) is used as the main curing agent, the content of the component (C) is such that the active hydrogen group of the component (C) is based on the epoxy group (1 equivalent) of the component (A). An amount of 0.8 to 1.2 equivalent is preferable. At this time, the content of the component (D) is such that the active hydrogen group of the component (D) is 0.05 to 0.15 equivalent with respect to the epoxy group (1 equivalent) of the component (A). preferable. The content of the component (C) is more preferably 0.9 to 1.1 equivalents of the active hydrogen group of the component (C) with respect to the epoxy group (1 equivalent) of the component (A). At this time, the content of the component (D) is such that the active hydrogen group of the component (D) is 0.05 to 0.10 equivalent with respect to the epoxy group (1 equivalent) of the component (A). More preferred.
A resin cured product having high heat resistance and moist heat resistance can be obtained by using the component (C) as the main curing agent, and diaminodiphenyl by using the component (D) as the secondary curing agent. It can compensate for the slow curing reaction of sulfone. In particular, if the active hydrogen group of the component (C) is 0.8 equivalent or more with respect to the epoxy group (1 equivalent) of the component (A), a cured resin product having high heat resistance and moisture heat resistance can be obtained. If the amount is 1.2 equivalents or less, the amount of the curing agent is excessive, and it is possible to suppress deterioration of the mechanical properties and heat resistance of the cured resin product. Further, if the active hydrogen group of the component (D) is 0.05 equivalent or more with respect to the epoxy group (1 equivalent) of the component (A), the slow curing reaction of diaminodiphenyl sulfone is supplemented and the resin flow is suppressed. If the amount is 0.15 equivalent or less, the curing reaction can be accelerated while maintaining high heat resistance and moisture heat resistance when cured with diaminodiphenyl sulfone.

The component (C) and the component (D) can be blended in the same amount, in which case the content of the component (C) is relative to the epoxy group (1 equivalent) of the component (A). The amount of the active hydrogen group of the component (C) is preferably 0.2 to 0.6 equivalent. At this time, the content of the component (D) is such that the active hydrogen group of the component (D) is 0.2 to 0.5 equivalent with respect to the epoxy group (1 equivalent) of the component (A). preferable.
If the active hydrogen group of the component (C) is 0.2 equivalent or more with respect to the epoxy group (1 equivalent) of the component (A), a cured resin product having high heat resistance and moisture heat resistance can be obtained. If the amount is 0.6 equivalent or less, the amount of the curing agent is excessive, and it is possible to suppress deterioration of the mechanical properties and heat resistance of the cured resin product. Further, if the active hydrogen group of the component (D) is 0.2 equivalent or more with respect to the epoxy group (1 equivalent) of the component (A), the slow curing reaction of diaminodiphenyl sulfone is supplemented and the resin flow is suppressed. If the amount is 0.5 equivalent or less, the curing reaction can be accelerated while maintaining high heat resistance and moisture heat resistance when cured with diaminodiphenyl sulfone.

<Component (E)>
The component (E) is a curing accelerator.
If the epoxy resin composition contains the component (E), the effect of further accelerating the curing reaction of the component (C) and the component (D), which are curing agents, can be obtained.
Specific examples of the component (E) include urea compounds, imidazoles, and Lewis salts. Among these, the urea compound is preferable because it can accelerate the curing reaction without affecting the mechanical properties and heat resistance of the cured resin product.
Examples of urea compounds include 1- (3,4-dichlorophenyl) -3,3-dimethylurea, 3- (3,4-dichlorophenyl) -1,1-dimethylurea, 1- (4-chlorophenyl) -3, 3-Dimethylurea, 1,1-dimethyl-3-phenylurea, 1- (3,4-dimethylphenyl) -3,3-dimethylurea, 1- (3,4-dimethylphenyl) -3,3-dimethyl Examples thereof include urea, 1- (2-hydroxyphenyl) -3,3-dimethylurea, 2,4-di (N, N-dimethylureide) -toluene, and 4,4'-methylenebis (phenyldimethylurea).

The content of the component (E) is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 7 parts by mass with respect to 100 parts by mass of the component (A). When the content of the component (E) is 0.1 parts by mass or more, the anti-curing reaction can be sufficiently accelerated and the resin flow can be further suppressed. When the content of the component (E) is 15 parts by mass or less, it is possible to suppress the influence on the mechanical properties and heat resistance of the cured resin product.

<Arbitrary ingredient>
The epoxy resin composition is, if necessary, a component (A), a component (B), a component (C), a component (D), and a component (as long as the effects of the present invention are not impaired. It may contain components other than E) (hereinafter, also referred to as "arbitrary components").
Examples of the optional component include various known additives.
Examples of the additive include a block copolymer composed of thermoplastic resin particles, core-shell elastomer particles, acrylic resin, etc., a compound having one epoxy group in the molecule, a diluent, inorganic particles (silica, etc.), and carbonaceous material. Examples include components (carbon nanotubes, etc.), flame retardants (phosphorus compounds, etc.), defoaming agents, and the like. Among these, thermoplastic resin particles are preferable as the additive from the viewpoint of improving the interlayer fracture toughness value without deteriorating the mechanical properties and heat resistance of the cured resin product.

The thermoplastic resin particles are particulate thermoplastic resins. Examples of the thermoplastic resin include polyacetal, polyethylene terephthalate, polyester, polyamide, polyurethane, polyethersulfone, polyetherimide, polycarbonate, polyimide, polyvinylformal, and copolymers thereof. One type of these thermoplastic resin particles may be used alone, or two or more types may be used in combination. Among these, polyamide is preferable from the viewpoint of imparting toughness to the carbon fiber reinforced composite material.
The polyamide is not particularly limited as long as it has an amide bond in the repeating structure. The polyamide may be polyamide particles made of one kind of polyamide, or may be polyamide particles made of two or more kinds of polyamides. When the polyamide is polyamide particles composed of two or more kinds of polyamides, each polyamide may be uniformly present in the particles or may be non-uniformly present as in a layered structure. Polyamide can be obtained by, for example, ring-opening polymerization of lactams, polycondensation of diamine and dicarboxylic acid, polycondensation of aminocarboxylic acid and the like. Specific examples of the polyamide include nylon 6, nylon 46, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6T, nylon 6I, nylon 9T, nylon M5T, and Dycel Ebonic's Trogamide (Trogamide). Examples thereof include polyamides containing an aromatic ring or an alicyclic ring such as T5000 (registered trademark) and CX7323 (registered trademark).

As the polyamide, either crystalline polyamide or amorphous polyamide can be preferably used, and either crystalline polyamide or amorphous polyamide may be used alone or in combination. ..
When a crystalline polyamide is used, its melting point is preferably 100 to 180 ° C., more preferably 120 to 180 ° C., and even more preferably 140 to 180 ° C. On the other hand, when an amorphous polyamide is used, its glass transition temperature is preferably 100 to 180 ° C, more preferably 120 to 180 ° C, and even more preferably 140 to 180 ° C. When the melting point of the crystalline polyamide and the glass transition temperature of the amorphous polyamide are within the above ranges, the effect of imparting toughness to the carbon fiber reinforced composite material by blending the thermoplastic resin particles becomes higher.

Examples of commercially available polyamide products include the VESTOSINT series manufactured by Daicel Ebonic (VESTOSINT (registered trademark) 2158, VESTOSINT® 2159, etc.); Grillamide (registered trademark) TR90NZ and Grillamide (registered trademark) TR55 manufactured by Ems-Chemie. Examples thereof include TOROGAMID (registered trademark) CX7323 and TOROGAMID (registered trademark) T5000 manufactured by Daicel Ebonic.

The thermoplastic resin particles may have any shape as long as they are in the form of particles, but they are preferably spherical, and more preferably true spherical. The closer the shape is to a true sphere, the higher the effect of imparting toughness to the carbon fiber reinforced composite material.

The average particle size of the thermoplastic resin particles is preferably 8 to 60 μm, more preferably 10 to 45 μm, and even more preferably 15 to 35 μm. When the average particle size of the thermoplastic resin particles is 8 μm or more, the thermoplastic resin particles do not easily penetrate into the carbon fiber base material when the carbon fiber base material is impregnated with the epoxy resin composition in the production of the prepreg. Easy to filter on the surface of the carbon fiber substrate. The more the thermoplastic resin particles are filtered out and abundantly present in the vicinity of the surface of the carbon fiber base material, the higher the effect of imparting toughness to the carbon fiber reinforced composite material by blending the thermoplastic resin particles becomes higher. When the average particle size of the thermoplastic resin particles is 60 μm or less, when the epoxy resin composition is thinly coated on a release paper or the like using a coating machine in the production of prepreg, the thermoplastic resin particles are applied to the coating machine. Is hard to clog. Further, when the carbon fiber reinforced composite material is produced, the straightness of the carbon fiber is unlikely to decrease.
The average particle size of the thermoplastic resin particles is a particle size corresponding to 50% of the cumulative distribution on a volume basis measured by the laser diffraction type particle size distribution measurement method.

The content of the thermoplastic resin particles is preferably 5 to 30 parts by mass, more preferably 8 to 25 parts by mass, and even more preferably 10 to 20 parts by mass with respect to 100 parts by mass of the component (A). If the content of the thermoplastic resin particles is 5 parts by mass or more, high toughness can be imparted to the carbon fiber reinforced composite material, and if it is 30 parts by mass or less, the handleability of the epoxy resin composition deteriorates or the prepreg It is possible to prevent deterioration of tackiness.

<Viscosity>
The control of the viscosity of the epoxy resin composition has a great influence on the control of the resin flow. In particular, when molding a large member such as in the aircraft field, it is necessary to raise the temperature to the curing temperature more slowly. Therefore, the viscosity of the epoxy resin composition until the curing reaction starts has a greater influence on the control of the resin flow.
In the present invention, when the viscosity measured by the following measuring method of the epoxy resin composition at the temperature T is η (T), the temperature T is in the range of 65 to 100 ° C. and is at 65 to 100 ° C. At any temperature within the range, η (T) satisfies the following equation (1). Further, it is preferable that η (T) satisfies the following formula (2) at any temperature in the range of 65 to 100 ° C.
5000exp (-0.08T) ≤ η (T) ... Equation (1)
η (T) ≤30000 exp (-0.08T) ... Equation (2)
In addition, "η (T)" indicates a viscosity at a temperature T. For example, "η (65)" is the viscosity of the epoxy resin composition at 65 ° C., and "η (100)" is the viscosity of the epoxy resin composition at 100 ° C.

That is, when the temperature T is in the range of 65 ° C. to 100 ° C., the viscosity η (T) is 5000 exp (−0.08 T) or more at any temperature in this temperature range. At any temperature in the range of 65 ° C. to 100 ° C., if the viscosity η (T) is 5000 exp (−0.08 T) or more, the resin flow can be suppressed to an appropriate range. .. When the temperature T is in the range of 65 ° C. to 100 ° C., the viscosity η (T) is preferably 5500 exp (−0.08 T) or more, preferably 6000 expp (−0.08 T) at any temperature within this temperature range. The above is more preferable.
Further, when the temperature T is in the range of 65 ° C. to 100 ° C., the viscosity η (T) is preferably 30,000 exp (−0.08 T) or less at any temperature within this temperature range. When the viscosity η (T) is 30,000 exp (−0.08 T) or less at any temperature in the range of 65 ° C. to 100 ° C., the carbon fiber base material is easily impregnated with the epoxy resin composition. The drapeability and tackiness of the produced prepreg can be set within an appropriate range. When the temperature T is in the range of 65 ° C. to 100 ° C., the viscosity η (T) is more preferably 20000 exp (-0.08 T) or less at any temperature in this temperature range, and 10000 exp (-0.08 T). ) The following is more preferable.

The viscosity can be determined by measuring the temperature rise viscosity of the epoxy resin composition. Specifically, the rheometer plate is preheated to 30 ° C., waits until the temperature stabilizes, and after confirming that the temperature has stabilized, the epoxy resin composition is separated into the plate and the gap is adjusted. , The viscosity of the epoxy resin composition is measured under the following measurement conditions.
(Measurement condition)
・ Equipment: Rheometer ・ Plate used: 35φ parallel plate ・ Plate gap: 0.5mm
-Measurement mode: constant stress-Measurement frequency: 10 rad / sec-Rising rate: From 30 ° C to at least the temperature immediately before the epoxy resin composition starts the curing reaction (that is, the temperature at which the viscosity rapidly increases) 2 The temperature is raised at ° C / min.
・ Stress: 300Pa

<Manufacturing method>
The epoxy resin composition contains, for example, a component (A), a component (B), a component (C) and a component (D), and if necessary, one or more of the component (E) and an optional component. Obtained by mixing.
Further, for example, a part of the component (A) and the component (D) are mixed with the component (E) as needed to prepare a masterbatch, and the remaining components are added to the obtained masterbatch. An epoxy resin composition may be produced by mixing the element (A), the component (B), the component (C), and an optional component, if necessary.
Examples of the mixing method of each component include a method using a mixer such as a three-roll mill, a planetary mixer, a kneader, a homogenizer, and a homodisper.

<Action effect>
The epoxy resin composition of the present invention described above includes the above-mentioned components (A), components (B), components (C) and components (D), and the viscosity at a specific temperature is defined. , Resin flow can be controlled and excellent molding and curing characteristics. Further, by using the epoxy resin composition of the present invention, a carbon fiber reinforced composite material having excellent mechanical properties and moisture heat resistance can be obtained.
The epoxy resin composition of the present invention is suitable as a matrix resin for a carbon fiber reinforced composite material containing carbon fibers and a matrix resin as essential components.

[Prepreg]
The prepreg of the present invention is a carbon fiber base material impregnated with the above-mentioned epoxy resin composition of the present invention, and is an intermediate material for producing a carbon fiber reinforced composite material.
The fiber basis weight of the prepreg (content of carbon fiber base material per 1 m ² : FAW) may be appropriately set according to the use of the prepreg, and is usually 50 to 300 g / m ² .

The content of the epoxy resin composition with respect to the total mass of the prepreg (hereinafter, referred to as “resin content”) is preferably 20 to 50% by mass, more preferably 30 to 40% by mass. When the resin content is 20% by mass or more, it is possible to prevent the tack of the prepreg from becoming too low, and to make the tack suitable for handling. Further, it is possible to prevent deterioration of the mechanical properties of the carbon fiber reinforced composite material due to the shortage of the epoxy resin composition. When the resin content is 50% by mass or less, the tack of the prepreg can be suppressed from becoming too high, and the tack can be made suitable for handling. Further, it is possible to prevent deterioration of the mechanical properties of the carbon fiber reinforced composite material due to the improvement of Vf (volume content of the carbon fiber base material in the carbon fiber reinforced composite material) due to the excess of the epoxy resin composition.

The thickness of the prepreg may be appropriately set according to the application of the prepreg, and is usually 0.05 to 0.3 mm.

<Carbon fiber base material>
As the carbon fiber base material, from the viewpoint that a carbon fiber reinforced composite material having high specific strength and specific elastic modulus can be formed, a sheet composed of a bundle of carbon fibers in which carbon fibers are aligned in one direction is used. From the viewpoint of being easy to handle, it is preferably a reinforcing fiber woven fabric.

The carbon fibers may be long fibers, and the long fibers may be in the form of strands. Further, the carbon fibers may be crushed (milled), long fibers, or the strands thereof may be cut (chopped).

The tensile strength of the carbon fiber is preferably 3500 MPa or more, more preferably 5000 MPa or more, and even more preferably 6000 MPa or more.
The tensile elastic modulus of the carbon fiber is preferably 150 GPa or more, more preferably 200 GPa or more, and further preferably 250 GPa or more.
The tensile strength and tensile modulus of carbon fibers are values measured in accordance with ASTM D4018.

The strand strength of the carbon fiber is not particularly limited. For example, when the carbon fiber reinforced composite material according to one embodiment is used as the structural material of an aircraft, the strand strength is high as the carbon fiber used for the carbon fiber reinforced composite material. It is preferable that the strand strength is 6000 MPa or more.
The strand strength of carbon fiber is a value measured in accordance with JIS R 7601.

The fiber diameter of the carbon fiber is preferably 3 μm or more, and preferably 12 μm or less. When the fiber diameter of the carbon fibers is 3 μm or more, in the process for processing the carbon fibers, for example, combs, rolls, etc., the carbon fibers move laterally and rub against each other, or the carbon fibers and the roll surface, etc. When rubbing against, the carbon fiber is less likely to be cut and fluff is less likely to occur. Therefore, a carbon fiber reinforced composite material having stable strength can be suitably produced. When the fiber diameter of the carbon fiber is 12 μm or less, the carbon fiber can be produced by a usual method.
The number of carbon fibers in the carbon fiber bundle is preferably 1,000 to 70,000.

<Manufacturing method>
The prepreg can be suitably produced by a wet method, a hot melt method, or the like.
Specifically, the wet method is a method in which the epoxy resin composition of the present invention is dissolved in a solvent such as methyl ethyl ketone or methanol to reduce the viscosity, and then the carbon fiber base material is impregnated.
Specifically, the hot melt method is a method in which the epoxy resin composition of the present invention is reduced in viscosity by heating and then directly impregnated into a carbon fiber base material, or the epoxy resin composition of the present invention is placed on a release paper or the like. This is a method in which a resin film is produced by coating, and a resin film is laminated on both sides or one side of a carbon fiber base material and heated and pressed.
From the viewpoint of the production environment and the characteristics of the carbon fiber reinforced composite material produced from the prepreg, the prepreg is preferably produced by the hot melt method.

<Action effect>
In the prepreg of the present invention described above, since the epoxy resin composition of the present invention is impregnated in the carbon fiber base material, the resin flow is controlled. Therefore, in the production of the carbon fiber reinforced composite material, the epoxy resin composition does not easily flow out of the system when the prepreg is heated. Further, by using the prepreg of the present invention, a carbon fiber reinforced composite material having excellent mechanical properties and moisture heat resistance can be obtained.

[Carbon fiber reinforced composite material]
The carbon fiber reinforced composite material of the present invention is obtained by curing the above-mentioned prepreg of the present invention, and includes a cured product of the epoxy resin composition of the present invention and a carbon fiber base material.

<Heat molding>
The carbon fiber reinforced composite material is obtained by laminating two or more prepregs to form a prepreg laminate, and heat-molding the prepreg laminate to cure the epoxy resin composition.
The temperature at which the prepreg laminate is heat-molded may be any temperature as long as the epoxy resin composition can be appropriately cured, but the performance of the equipment used for the heat-molding, the properties of the auxiliary materials, and the obtained carbon fiber 170 to 190 ° C. is preferable from the viewpoint of the characteristics of the reinforced composite material and the time required for curing the epoxy resin composition. When the temperature at the time of heat molding is 170 ° C. or higher, the epoxy resin composition is sufficiently cured, and a carbon fiber reinforced composite material having higher heat resistance can be obtained. If the temperature at the time of heat molding is 190 ° C. or lower, cheaper materials can be used as equipment and auxiliary materials used for heat molding.

The heat molding time may be any time as long as the epoxy resin composition can be sufficiently cured and is suitable for the heat molding method described later. For example, in the case of the autoclave molding method, the heat molding time is preferably 1 to 4 hours. If the heat molding time is 1 hour or more, the epoxy resin composition is sufficiently cured. If the heat molding exceeds 4 hours, the manufacturing cost becomes higher.

Examples of the heat molding method include known methods such as an autoclave molding method, an oven molding method, and a press molding method. As the heat molding method, the autoclave molding method is preferable from the viewpoint that a fiber-reinforced composite material having more excellent mechanical properties can be obtained.

<Action effect>
The carbon fiber reinforced composite material described above uses a prepreg impregnated in a carbon fiber base material with the epoxy resin composition of the present invention as an intermediate material, and thus has excellent mechanical properties and moisture and heat resistance.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following description.
The raw materials used in each Example and Comparative Example and various measurement and evaluation methods are as follows.

[material]
<Component (A)>
-JER828: A bisphenol A type epoxy resin liquid at 25 ° C. (manufactured by Mitsubishi Chemical Corporation, jER (registered trademark) 828).
-JER807: A bisphenol F type epoxy resin liquid at 25 ° C. (manufactured by Mitsubishi Chemical Corporation, jER (registered trademark) 807).
-JER604: Tetraglycidyl diaminodiphenylmethane (manufactured by Mitsubishi Chemical Corporation, jER (registered trademark) 604).
MY0510: Triglycidyl-p-aminophenol (Huntsman Corporation, Araldite® MY0510).
TSR-400: An epoxy resin having an oxazolidone ring skeleton (EPICLON (registered trademark) TSR-400 manufactured by DIC Corporation).

<Component (B)>
-5003MP: Polyether sulfone (manufactured by Sumitomo Chemical Co., Ltd., Sumika Excel PES5003MP).

<Component (C)>
-SEIKACURE-S: 4,4'-diaminodiphenyl sulfone (manufactured by Wakayama Seika Kogyo Co., Ltd., SEIKACURE-S).

<Component (D)>
-DICY7: dicyandiamide (manufactured by Mitsubishi Chemical Corporation, jER Cure (registered trademark) DICY7).

<Component (E)>
-DCMU: 3- (3,4-diclophenyl) -1,1-dimethylurea (manufactured by Hodogaya Chemical Co., Ltd., DCMU99).

<Carbon fiber base material>
-TR50S: Carbon fiber bundle (manufactured by Mitsubishi Chemical Corporation, Pyrofil (registered trademark) TR50S).

[Measurement / evaluation]
<Measurement of temperature rise viscosity of epoxy resin composition>
The rheometer plate was preheated to 30 ° C. and waited for the temperature to stabilize. After confirming that the temperature was stable, the epoxy resin composition was dispensed onto a plate, the gap was adjusted, and then the viscosity of the epoxy resin composition was measured under the following measurement conditions.
(Measurement condition)
・ Equipment: Rheometer (Thermo Fisher, HAAKE MARS40)
・ Plate used: 35φ parallel plate ・ Plate gap: 0.5mm
-Measurement mode: constant stress-Measurement frequency: 10 rad / sec-Rising rate: From 30 ° C to at least the temperature immediately before the epoxy resin composition starts the curing reaction (that is, the temperature at which the viscosity rapidly increases) 2 The temperature was raised at ° C / min.
・ Stress: 300Pa

<Water absorption rate of cured product of epoxy resin composition>
The water absorption rate of the cured product (cured resin product) of the epoxy resin composition was measured by the following method.
1) A cured plate of a 2 mm thick epoxy resin composition was prepared. The curing conditions of the epoxy resin composition were that the temperature was raised from room temperature to 180 ° C. at 1.7 ° C./min, held at 180 ° C. for 2 hours, and allowed to cool naturally to 50 ° C. or lower.
2) Within 24 hours after curing, the cured plate was processed into a length of 55 mm and a width of 12.7 mm to prepare a test piece for measuring water absorption.
3) The dirt on the test piece was wiped off with acetone, and the mass of the cured resin test piece before water absorption was measured.
4) The test piece was immersed in warm water at 71 ° C. for 2 weeks to perform a water absorption test. When immersing a plurality of test pieces, each test piece was wrapped with gauze so that the test pieces did not come into direct contact with each other.
5) The immersed test piece was taken out, water droplets were sufficiently wiped off, and the mass of the test piece after water absorption was measured.
6) The water absorption rate of the cured resin product was calculated from the following formula (3).
Water absorption rate (%) = (mass of test piece after water absorption-mass of test piece before water absorption) / mass of test piece before water absorption x 100 ... Equation (3)

<Three-point bending test of cured product of epoxy resin composition>
A 2 mm-thick cured plate prepared under the same conditions as the measurement of the water absorption rate of the cured resin product was processed into a length of 60 mm and a width of 8 mm to prepare a test piece for a three-point bending test.
For the obtained test piece, an electromechanical universal material tester (manufactured by Instron) equipped with a three-point bending jig (both indenter and support tip 3.2 mmR, distance between supports: 16 times the test piece thickness) was installed. The bending characteristics (bending strength, flexural modulus, breaking strain) of the cured resin product were measured under the condition of a crosshead speed of 2 mm / min.

<Glass transition temperature of cured product of epoxy resin composition>
A 2 mm-thick cured plate prepared under the same conditions as the measurement of the water absorption rate of the cured resin product was processed into a length of 55 mm and a width of 12.7 mm to prepare a test piece for measuring the glass transition temperature.
The obtained test piece was subjected to a water absorption test under the same conditions as the measurement of the water absorption rate of the cured resin product.
Twist mode for test pieces before and after the water absorption test using a dynamic viscoelasticity measuring device (ARES-RDA, manufactured by TA Instruments) under the conditions of frequency 1 Hz and temperature rise rate 5 ° C / min. The storage elastic modulus G'was measured at. The log G'is plotted against the temperature, and the temperature obtained from the intersection of the approximate straight line of the log G'in the flat region before the transition to the rubber state and the approximate straight line of the log G'in the region after the transition to the rubber state is measured by the glass. The transition temperature was used. The glass transition temperature of the cured resin product before the water absorption test was defined as "G'-Tg Dry", and the glass transition temperature of the cured resin product after the water absorption test was defined as "G'-Tg Wet".

<Measurement of resin flow rate during curing process>
Twelve prepregs cut into 150 mm squares were laminated so that the axial directions of the carbon fibers were aligned to obtain a prepreg laminate. The obtained prepreg laminate was bagged as follows.
As shown in FIG. 1, a release film 2a was laid on the metal tool 1, and a prepreg laminate 3 was placed on the release film 2a. A glass sleeve 4a was arranged around the prepreg laminate 3. At this time, an interval of about 25 mm was provided from the end of the prepreg laminated body 3 to the glass sleeve 4a. The glass yarn 5 was arranged along the edge of the prepreg laminate 3, and both ends of the glass yarn 5 were fixed to the glass sleeve 4a with heat-resistant tape (not shown). The release film 2b was laminated on the upper surface of the prepreg laminated body 3. The size of the release film 2b was set so that the glass sleeve 4a was half covered. Further, a metal plate 6 and a nylon non-woven fabric 7a were laminated on the release film 2b. At the time of curing, the epoxy resin composition flows from the prepreg laminate 3 toward the mouthpiece 8 in order to pressurize the inside of the autoclave and depressurize the inside of the bag. A nylon non-woven fabric 7b was placed in the path through which the epoxy resin composition flowed so that the epoxy resin composition remained intentionally. Specifically, the glass sleeve 4b was arranged so as to be in contact with the mouthpiece 8, and the nylon non-woven fabric 7b was arranged between the glass sleeve 4b and the glass sleeve 4a arranged around the prepreg laminate 3. The glass sleeves 4a and 4b and the non-woven fabric 7b were connected by a glass yarn 5. The non-woven fabric 7b was made large enough to hold the epoxy resin composition. The bagging film 9 was covered and the end was sealed with the sealant 10. In FIG. 1B, the release film 2a, the metal plate 6, the non-woven fabric 7a, and the bagging film 9 are omitted.
The bagged prepreg laminate was cured using an autoclave. Specifically, the temperature is raised from room temperature to 65 ° C. at 1 ° C./min, held at 65 ° C. for 20 minutes, further raised to 180 ° C. at 1 ° C./min, held at 180 ° C. for 120 minutes, and then 3 The temperature was lowered to 50 ° C. or lower at ° C./min, and then the cured product was removed from the autoclave. The flow rate was calculated from the following formula (4) from the mass (Wb) of the prepreg laminate before curing and the mass (Wa) of the prepreg laminate after curing.
Flow rate (%) = (Wb-Wa) / Wb × 100 ... Equation (4)

[Example 1]
<Preparation of epoxy resin composition>
Each raw material was weighed so that the mass ratio of jER828, DICY7, and DCMU was 6: 3: 2. A masterbatch was prepared by uniformly kneading the weighed raw materials using Mazerustar KK-2000 (manufactured by Kurabo Industries Ltd.) and a three-roll mill. Weigh 38 parts by mass of jER828, 50 parts by mass of jER604, and 15 parts by mass of 5003MP in a separable flask, and use an oil bath set at 160 to 170 ° C., a stirrer three-one motor and its stirring blade to make the weighed raw materials uniform. It was heated and stirred until it became. The separable flask was taken out from the oil bath, and when the temperature of the contents became 70 ° C. or lower, 9.1 parts by mass of SEIKACURE-S and 22 parts by mass of the masterbatch were weighed into the separable flask. An epoxy resin composition was prepared by heating and stirring until the contents of the separable frass heco became uniform using a water bath set at 60 to 70 ° C., a stirrer three-one motor and a stirring blade thereof.
The viscosity of the obtained epoxy resin composition was measured. The results are shown in FIG. Further, it is confirmed whether or not the viscosity η (T) of the epoxy resin composition at the temperatures of 65 ° C. and 100 ° C. satisfies the above formula (1). ". The results are shown in Table 1. Note that FIG. 2 also shows a straight line represented by y = 5000e ^−0.08T (where y is viscosity and T is temperature).
In addition, the bending characteristics, glass transition temperature and water absorption rate of the cured resin product were measured. These results are shown in Table 1.

<Making prepreg>
An epoxy resin composition was applied onto a paper pattern using a hot melt coater to prepare a resin film. A resin film is attached to the top and bottom of the carbon fiber base material prepared by aligning the carbon fiber TR50S in one direction, and the epoxy resin composition is impregnated into the carbon fiber base material by heating and pressurizing the prepreg. Made.
Using the obtained prepreg, the resin flow rate in the curing process was measured. The results are shown in Table 1.

[Example 2]
<Preparation of epoxy resin composition>
A masterbatch was prepared in the same procedure as in Example 1. Weigh 5 parts by mass of jER828, 55 parts by mass of jER807, 35 parts by mass of jER604, 5 parts by mass of MY0510, and 13 parts by mass of 5003MP in a separable flask, and weigh an oil bath set at 160 to 170 ° C., a stirrer three-one motor and its Using a stirring blade, the mixture was heated and stirred until the weighed raw materials became uniform. The separable flask was taken out from the oil bath, and when the temperature of the contents became 70 ° C. or lower, 43 parts by mass of SEIKACURE-S and 5.7 parts by mass of the masterbatch were weighed into the separable flask. An epoxy resin composition was prepared by heating and stirring until the contents of the separable frass heco became uniform using a water bath set at 60 to 70 ° C., a stirrer three-one motor and a stirring blade thereof. The content of the component (B) in the obtained epoxy resin composition is 12.61 parts by mass with respect to 100 parts by mass of the component (A). The content of the component (E) is 0.77 parts by mass with respect to 100 parts by mass of the component (A).
The viscosity of the obtained epoxy resin composition was measured. The results are shown in FIG. Further, it was confirmed whether or not the viscosity η (T) of the epoxy resin composition at temperatures of 65 ° C. and 100 ° C. satisfied the above formula (1). The results are shown in Table 1.
In addition, the bending characteristics, glass transition temperature and water absorption rate of the cured resin product were measured. These results are shown in Table 1.

<Making prepreg>
A prepreg was prepared in the same procedure as in Example 1 except that the obtained epoxy resin composition was used.
Using the obtained prepreg, the resin flow rate in the curing process was measured. The results are shown in Table 1.

[Reference example A]
<Preparation of epoxy resin composition>
A masterbatch was prepared in the same procedure as in Example 1. Weigh 42 parts by mass of jER828, 50 parts by mass of jER604, and 15 parts by mass of 5003MP in a separable flask, and use an oil bath set at 160 to 170 ° C., a stirrer three-one motor and its stirring blade to make the weighed raw materials uniform. It was heated and stirred until it became. The separable flask was taken out from the oil bath, and when the temperature of the contents became 70 ° C. or lower, 18.7 parts by mass of SEIKACURE-S and 14.7 parts by mass of the masterbatch were weighed into the separable flask. An epoxy resin composition was prepared by heating and stirring until the contents of the separable frass heco became uniform using a water bath set at 60 to 70 ° C., a stirrer three-one motor and a stirring blade thereof.
The viscosity of the obtained epoxy resin composition was measured. Further, it was confirmed whether or not the viscosity η (T) of the epoxy resin composition at temperatures of 65 ° C. and 100 ° C. satisfied the above formula (1). The results are shown in Table 1.
In addition, the bending characteristics, glass transition temperature and water absorption rate of the cured resin product were measured. These results are shown in Table 1.

<Making prepreg>
A prepreg was prepared in the same procedure as in Example 1 except that the obtained epoxy resin composition was used.
Using the obtained prepreg, the resin flow rate in the curing process was measured. The results are shown in Table 1.

[Comparative Example 1]
<Preparation of epoxy resin composition>
Weigh 49 parts by mass of jER807, 16 parts by mass of jER604, 35 parts by mass of TSR-400, and 2.8 parts by mass of 5003MP in a separable flask, and weigh an oil bath set at 160 to 170 ° C., a stirrer three-one motor and its stirring blade. Was heated and stirred until the weighed raw materials became uniform. The separable flask was taken out from the oil bath, and when the temperature of the contents became 70 ° C. or lower, 40.6 parts by mass of SEIKACURE-S was weighed into the separable flask. An epoxy resin composition was prepared by heating and stirring until the contents of the separable frass heco became uniform using a water bath set at 60 to 70 ° C., a stirrer three-one motor and a stirring blade thereof.
The viscosity of the obtained epoxy resin composition was measured. The results are shown in FIG. Further, it was confirmed whether or not the viscosity η (T) of the epoxy resin composition at temperatures of 65 ° C. and 100 ° C. satisfied the above formula (1). The results are shown in Table 1.
In addition, the bending characteristics, glass transition temperature and water absorption rate of the cured resin product were measured. These results are shown in Table 1.

<Making prepreg>
A prepreg was prepared in the same procedure as in Example 1 except that the obtained epoxy resin composition was used.
Using the obtained prepreg, the resin flow rate in the curing process was measured. The results are shown in Table 1.

[Comparative Example 2]
<Preparation of epoxy resin composition>
A masterbatch was prepared in the same procedure as in Example 1. Weigh 49 parts by mass of jER807, 16 parts by mass of jER604, 35 parts by mass of TSR-400, and 2.8 parts by mass of 5003MP in a separable flask, and weigh an oil bath set at 160 to 170 ° C., a stirrer three-one motor and its stirring blade. Was heated and stirred until the weighed raw materials became uniform. The separable flask was taken out from the oil bath, and when the temperature of the contents became 70 ° C. or lower, 33 parts by mass of SEIKACURE-S and 5.7 parts by mass of the masterbatch were weighed into the separable flask. An epoxy resin composition was prepared by heating and stirring until the contents of the separable frass heco became uniform using a water bath set at 60 to 70 ° C., a stirrer three-one motor and a stirring blade thereof. The content of the component (B) in the obtained epoxy resin composition is 2.72 parts by mass with respect to 100 parts by mass of the component (A). The content of the component (E) is 0.77 parts by mass with respect to 100 parts by mass of the component (A).
The viscosity of the obtained epoxy resin composition was measured. The results are shown in FIG. Further, it was confirmed whether or not the viscosity η (T) of the epoxy resin composition at temperatures of 65 ° C. and 100 ° C. satisfied the above formula (1). The results are shown in Table 1.
In addition, the bending characteristics, glass transition temperature and water absorption rate of the cured resin product were measured. These results are shown in Tables 1 and 2.

<Making prepreg>
A prepreg was prepared in the same procedure as in Example 1 except that the obtained epoxy resin composition was used.
Using the obtained prepreg, the resin flow rate in the curing process was measured. The results are shown in Table 1.

[Reference Examples B and C]
The following Reference Example B and Reference Example C were carried out in order to confirm the influence of the addition amount of the component (D) on the bending characteristics, the glass transition temperature and the water absorption rate of the cured resin product.

[Reference Example B]
<Preparation of epoxy resin composition>
A masterbatch was prepared in the same procedure as in Example 1. Weigh 49 parts by mass of jER807, 16 parts by mass of jER604, 35 parts by mass of TSR-400, and 2.8 parts by mass of 5003MP in a separable flask, and weigh an oil bath set at 160 to 170 ° C., a stirrer three-one motor and its stirring blade. Was heated and stirred until the weighed raw materials became uniform. The separable flask was taken out from the oil bath, and when the temperature of the contents became 70 ° C. or lower, 33 parts by mass of SEIKACURE-S and 2.75 parts by mass of the masterbatch were weighed into the separable flask. An epoxy resin composition was prepared by heating and stirring until the contents of the separable frass heco became uniform using a water bath set at 60 to 70 ° C., a stirrer three-one motor and a stirring blade thereof. The content of the component (B) in the obtained epoxy resin composition is 2.76 parts by mass with respect to 100 parts by mass of the component (A). The content of the component (E) is 0.49 parts by mass with respect to 100 parts by mass of the component (A).
The bending characteristics, glass transition temperature and water absorption of the cured resin were measured. These results are shown in Table 2.

<Making prepreg>
A prepreg was prepared in the same procedure as in Example 1 except that the obtained epoxy resin composition was used.

[Reference Example C]
<Preparation of epoxy resin composition>
A masterbatch was prepared in the same procedure as in Example 1. Weigh 49 parts by mass of jER807, 16 parts by mass of jER604, 35 parts by mass of TSR-400, and 2.8 parts by mass of 5003MP in a separable flask, and weigh an oil bath set at 160 to 170 ° C., a stirrer three-one motor and its stirring blade. Was heated and stirred until the weighed raw materials became uniform. The separable flask was taken out from the oil bath, and when the temperature of the contents became 70 ° C. or lower, 33 parts by mass of SEIKACURE-S and 7.3 parts by mass of the masterbatch were weighed into the separable flask. An epoxy resin composition was prepared by heating and stirring until the contents of the separable frass heco became uniform using a water bath set at 60 to 70 ° C., a stirrer three-one motor and a stirring blade thereof. The content of the component (B) in the obtained epoxy resin composition is 2.69 parts by mass with respect to 100 parts by mass of the component (A). The content of the component (E) is 1.25 parts by mass with respect to 100 parts by mass of the component (A).
The bending characteristics, glass transition temperature and water absorption of the cured resin were measured. These results are shown in Table 2.

<Making prepreg>
A prepreg was prepared in the same procedure as in Example 1 except that the obtained epoxy resin composition was used.

As shown in FIG. 2, when Comparative Example 1 and Comparative Example 2 are compared, the viscosities at a temperature higher than 100 ° C. are different. It can be seen that the epoxy resin composition of Comparative Example 2 containing the component (D) and the component (E) has a faster curing reaction than Comparative Example 1 and can maintain a high viscosity. Therefore, the resin flow rate in the curing process is also lower in Comparative Example 1 and Comparative Example 2. However, in the epoxy resin compositions of Comparative Examples 1 and 2, the viscosity η (T) may or may not satisfy the formula (1) in the range of 65 to 100 ° C. depending on the temperature. The rate is high, and the epoxy resin composition easily flows out.
On the other hand, the epoxy resin compositions of Examples 1 and 2 both contain the component (D) and the component (E), have a rapid curing reaction, and have a viscosity η at any temperature within the range of 65 to 100 ° C. Since (T) satisfies the formula (1), the resin flow rate is low and the molding and curing characteristics are excellent. Further, from the results of the bending property and the water absorption rate, it was shown that the carbon fiber reinforced composite material having excellent mechanical properties and moisture heat resistance can be obtained by using the epoxy resin compositions of Examples 1 and 2.

In particular, when Example 2, Comparative Examples 1 and 2, and Reference Examples B and C are compared, the active hydrogen group of the component (C) is 0.8 with respect to the epoxy group (1 equivalent) of the component (A). When it is contained in the range of ~ 1.2 equivalents, the elastic modulus of the cured resin product tends to be improved and the breaking strain tends to be lowered by blending the component (D). In addition, the glass transition temperature, which is an index of the heat resistance of the cured resin product, tends to decrease. However, if the content of the component (D) is too large (Reference Example C), the glass transition temperature of the cured resin product will drop too much. Therefore, when the active hydrogen group of the component (C) is in the range of 0.8 to 1.2 equivalents with respect to the epoxy group (1 equivalent) of the component (A), the content of the component (D) The amount of the active hydrogen group of the component (D) is 0.05 to 0.15 equivalent with respect to the epoxy group (1 equivalent) of the component (A) for controlling the tree species flow and the cured resin product. It was shown that the characteristics of epoxide can be maintained in a more balanced manner.

1 Metal tool 2a Release film 2b Release film 3 Prepreg laminate 4a Glass sleeve 4b Glass sleeve 5 Glass yarn 6 Metal plate 7a Non-woven fabric 7b Non-woven fabric 8 Mouthpiece 9 Bagging film 10 Sealant

Claims (9)

An epoxy resin composition for a carbon fiber reinforced composite material, which comprises the following components (A), components (B), components (C) and components (D).
The content of the following component (B) is 5 to 25 parts by mass with respect to 100 parts by mass of the following component (A).
When the viscosity measured by the following measuring method of the epoxy resin composition for carbon fiber reinforced composite material at the temperature T is η (T), the temperature T is in the range of 65 to 100 ° C., and is 65 to 100. An epoxy resin composition for a carbon fiber reinforced composite material in which η (T) satisfies the following formula (1) at any temperature within the range of ° C.
Component (A): Epoxy resin Component (B): Thermoplastic resin Component (C): Diaminodiphenyl sulfone Component (D): Dicyanodiamide 5000exp (-0.08T) ≤ η (T) ... 1)
<Measurement method>
The rheometer plate is preheated to 30 ° C., waits until the temperature stabilizes, and after confirming that the temperature has stabilized, the epoxy resin composition is separated into the plate, the gap is adjusted, and then the following measurement conditions are applied. Measure the viscosity of the epoxy resin composition with.
(Measurement condition)
・ Equipment: Rheometer ・ Plate used: 35φ parallel plate ・ Plate gap: 0.5mm
-Measurement mode: constant stress-Measurement frequency: 10 rad / sec-Rising rate: From 30 ° C. to at least the temperature immediately before the epoxy resin composition starts the curing reaction, the temperature is raised at 2 ° C./min.
・ Stress: 300Pa The carbon fiber reinforced according to claim 1, wherein the temperature T is in the range of 65 to 100 ° C., and the η (T) satisfies the following formula (2) at any temperature in the range of 65 to 100 ° C. Epoxy resin composition for composite materials.
η (T) ≤30000 exp (-0.08T) ... Equation (2) The content of the component (C) is such that the active hydrogen group of the component (C) is 0.8 to 1.2 equivalents with respect to the epoxy group of the component (A), and the content is the same. Claim 1 that the content of the component (D) is such that the active hydrogen group of the component (D) is 0.05 to 0.15 equivalent with respect to the epoxy group of the component (A). Alternatively, the epoxy resin composition for a carbon fiber reinforced composite material according to 2. The content of the component (C) is such that the active hydrogen group of the component (C) is 0.2 to 0.6 equivalent to the epoxy group of the component (A), and the content is the same. Claim 1 in which the content of the component (D) is such that the active hydrogen group of the component (D) is 0.2 to 0.5 equivalent with respect to the epoxy group of the component (A). Alternatively, the epoxy resin composition for a carbon fiber reinforced composite material according to 2. The epoxy resin composition for a carbon fiber reinforced composite material according to any one of claims 1 to 4, wherein the component (B) is a polyether sulfone. The epoxy resin composition for a carbon fiber reinforced composite material according to any one of claims 1 to 5, further comprising the following component (E).
Component (E): Hardening accelerator The epoxy resin composition for a carbon fiber reinforced composite material according to claim 6, wherein the component (E) is a urea compound. A prepreg in which a carbon fiber base material is impregnated with the epoxy resin composition for a carbon fiber reinforced composite material according to any one of claims 1 to 7. A carbon fiber reinforced composite material obtained by curing the prepreg according to claim 8.

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