JP2022039265A - Epoxy resin composition, tow prepreg and fiber-reinforced composite material - Google Patents

Abstract

To provide an epoxy resin composition which enables production of a cured product that has excellent deformability and fracture toughness, and excellent heat resistance, water resistance and speed curability, and a tow prepreg and a fiber-reinforced composite material using the epoxy resin composition.SOLUTION: An epoxy resin composition contains all of the following components [A] to [E], and satisfies conditions [a] and [b]. [A]: The epoxy resin contains at least [A1] and [A2]: [A1] a bisphenol type epoxy resin, and [A2] a bifunctional aliphatic epoxy resin containing straight chain or branched alkylene and cycloalkyl alkylene groups. [B]: carboxyl group-terminated butadiene nitrile rubber. [C]: core-shell type rubber particles. [D]: dicyandiamide. [E]: aromatic urea. [a]: Hansen solubility parameter of the component [A2] is 9.0 to 9.8(cal/cm3)05. [b]: a ratio of a molar number of the component [D] to a molar number of an urea group of the component [E] is 2.0-9.0.SELECTED DRAWING: None

Description

The present invention relates to an epoxy resin composition preferably used as a matrix resin of a fiber-reinforced composite material suitable for sports use and general industrial use, and a tow prepreg and a fiber-reinforced composite material using the same as a matrix resin.

The epoxy resin composition is widely used as a matrix resin for a fiber-reinforced composite material by taking advantage of its features of high heat resistance, adhesiveness, and mechanical strength. In the production of the fiber-reinforced composite material, an intermediate base material in which the reinforcing fibers are impregnated in advance with a matrix resin is often used because of the ease of transportation and shape-impartment. The form of the intermediate base material is a prepreg in which reinforcing fibers impregnated with a matrix resin are arranged in a sheet shape, or a narrow intermediate base material such as a tow prepreg or a yarn prepreg in which the reinforcing fibers are impregnated with a matrix resin (hereinafter referred to as tow). Prepreg) and the like.

With the expansion of the application of intermediate base materials to general industrial applications such as automobile parts, it is desired to improve the long-term durability, heat resistance, and water resistance of fiber-reinforced composite materials. In order to improve long-term durability, it is necessary to improve the deformability and fracture toughness of the matrix resin (epoxy resin). Further, in order to improve the water resistance, it is necessary to reduce the water absorption. Further, in order to improve the heat resistance, it is necessary to improve the glass transition point temperature.

Further, due to the demand for high productivity, it is also required to increase the curing speed of the epoxy resin.

Patent Document 1 discloses a technique for improving the surface quality and fracture toughness of a tow prepreg by using an epoxy resin composition containing a large amount of core-shell type rubber particles.

Patent Document 2 discloses a low-viscosity epoxy resin composition in which fine particles containing a rubber component insoluble in an epoxy resin and a 1-2 functional epoxy resin are used in combination to increase the toughness of the cured product.

Patent Document 3 describes an epoxy resin composition for tow prepreg in which a low-viscosity epoxy resin and a core-shell type rubber particle are used in combination to increase the fracture toughness value of a cured epoxy resin product.

International Publication No. 2017/09960 Japanese Unexamined Patent Publication No. 9-227693 Japanese Unexamined Patent Publication No. 2011-157491

Since the epoxy resin composition described in Patent Document 1 contains a large amount of core-shell type rubber particles, the mechanical properties of the cured epoxy resin have not been sufficient. In addition, there is no mention of improving the deformability.

The epoxy resin compositions described in Patent Documents 2 and 3 show relatively high breaking toughness, but they are deformed probably because the epoxy resin composition uses a large amount of a 1-2 functional epoxy resin and the cross-linking is insufficient. It had low capacity and heat resistance.

The present invention is an epoxy resin composition capable of improving the drawbacks of the prior art, exhibiting excellent deformation ability and breaking toughness, and obtaining a cured product having excellent water resistance, heat resistance, and quick curing property, and an epoxy resin composition. It is an object of the present invention to provide a tow prepreg composed of the epoxy resin composition and reinforcing fibers, and a fiber-reinforced composite material obtained by curing the tow prepreg.

As a result of diligent studies to solve the above problems, the present inventors have found an epoxy resin composition having the following constitution, and have completed the present invention. That is, the epoxy resin composition of the present invention contains all of the following components [A] to [E] and satisfies the conditions [a] and [b].
[A]: Epoxy resin [A1] including at least [A1] and [A2]: Bisphenol type epoxy resin [A2]: Represented by the following chemical formula (I), and X in the chemical formula (I) is as follows ( Bifunctional aliphatic epoxy resin satisfying either 1) or (2)

(1) Linear or branched alkylene having 4 to 10 carbon atoms (2) Cycloalkylalkylene [B] having 4 to 10 carbon atoms: carboxyl group-terminated butadiene nitrile rubber [C]: core-shell type rubber particles [D]: dicyandiamide [E]: Aromatic urea [a]: Hansen solubility parameter of component [A2] is 9.0 to 9.8 (cal / cm ³ ) ^0.5 .
[B]: The ratio of the number of moles of the component [D] to the number of moles of the urea group of the component [E] is 2.0 to 9.0.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an epoxy resin composition which exhibits excellent deformation ability and fracture toughness, and can obtain a cured product having excellent water resistance, heat resistance, and quick curing property.

The present invention has the following configuration. That is, it is an epoxy resin composition containing all of the following components [A] to [E] and satisfying the conditions [a] and [b].
[A]: Epoxy resin [A1] including at least [A1] and [A2]: Bisphenol type epoxy resin [A2]: Represented by the following chemical formula (I), and X in the chemical formula (I) is as follows ( Bifunctional aliphatic epoxy resin satisfying either 1) or (2)

(1) Linear or branched alkylene having 4 to 10 carbon atoms (2) Cycloalkylalkylene [B] having 4 to 10 carbon atoms: carboxyl group-terminated butadiene nitrile rubber [C]: core-shell type rubber particles [D]: dicyandiamide [E]: Aromatic urea [a]: Hansen solubility parameter of component [A2] is 9.0 to 9.8 (cal / cm ³ ) ^0.5 .
[B]: The ratio of the number of moles of the component [D] to the number of moles of the urea group of the component [E] is 2.0 to 9.0.

The component [A1] in the present invention is a bisphenol type epoxy resin. The bisphenol type epoxy resin is widely used as the main agent of the epoxy resin because it is relatively inexpensive and has an excellent balance of mechanical properties and heat resistance of the cured epoxy resin obtained by using it as the main agent.

Specific examples of the component [A1] include bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin. These may be used alone or in combination of two or more.

Among such components [A1], examples of commercially available bisphenol A type epoxy resins include "jER" (registered trademark) 828, 1001, 1007 (all manufactured by Mitsubishi Chemical Corporation). Commercially available products of the above bisphenol F type epoxy resin include "EPICLON" (registered trademark) 830, 807 (above, manufactured by DIC Corporation), "jER" (registered trademark) 806, 4007P (above, Mitsubishi Chemical (above, Mitsubishi Chemical Corporation)). (Made by Toto Kasei Co., Ltd.), “Epototo” (registered trademark) YDF-2001 (manufactured by Toto Kasei Co., Ltd.), and the like. Commercially available products of the above bisphenol S type epoxy resin include "EPICLON" (registered trademark) EXA-1514, "EPICLON" EXA-1517 (above, manufactured by DIC Corporation), YL7487, YL7459 (above, Mitsubishi Chemical (above, Mitsubishi Chemical Corporation)). Made by Co., Ltd.).

The component [A1] in the present invention is preferably a bisphenol type epoxy resin that is liquid at 25 ° C. because the viscosity of the epoxy resin composition can be made more suitable as the matrix resin for tow prepreg. Above all, it is more preferable to contain a bisphenol A type epoxy resin that is liquid at 25 ° C. because an epoxy resin composition having an excellent balance between price, mechanical properties of the cured product, and heat resistance can be obtained.

In the present invention, the component [A1] is included within a range that does not impair the effects of the component [A2], the component [B], and the component [C] described later.

The component [A2] in the present invention is a bifunctional aliphatic epoxy resin represented by the following chemical formula (I) and in which X in the chemical formula (I) satisfies either of the following (1) or (2). A bifunctional aliphatic epoxy resin represented by the following chemical formula (I) and in which X in the chemical formula (I) satisfies any of the following (1) or (2) is a bifunctional aliphatic. It may also be described as epoxy resin or component [A2]).

(1) Linear or branched alkylene having 4 to 10 carbon atoms (2) Cycloalkyl alkylene having 4 to 10 carbon atoms.

Specific examples of such component [A2] include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,8-octanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and cyclohexanedi. Examples thereof include methanol diglycidyl ether.

Commercially available products of such component [A2] include "Denacol" (registered trademark) EX-214 (1,4-butanediol diglycidyl ether, manufactured by Nagase ChemteX Corporation), "Araldite" (registered trademark) DY-. 026 (1,4-butanediol diglycidyl ether, manufactured by Huntsman Japan Co., Ltd.), "Denacol" (registered trademark) EX-212 (1,6-hexanediol diglycidyl ether, manufactured by Nagase ChemteX Corporation) , "Adecaledin" (registered trademark) ED-503 (1,6-hexanediol diglycidyl ether, manufactured by ADEKA Co., Ltd.), "Denacol" (registered trademark) EX-211 (neopentyl glycol diglycidyl ether, Nagasechemtex) ED-523 (Neopentyl glycol diglycidyl ether, ADEKA Co., Ltd.), "Denacol" (registered trademark) EX-216 (cyclohexanedimethanol diglycidyl ether, Nagase) Chemtex Co., Ltd.), "Ricaresin" (registered trademark) DME-100 (cyclohexanedimethanol diglycidyl ether, Shin Nihon Rika Co., Ltd.) and the like can be mentioned.

The epoxy resin composition in the present invention preferably contains 2 to 18 parts by mass of the component [A2], more preferably 3 to 15 parts by mass, and 4 to 15 parts by mass in 100 parts by mass of the total epoxy resin. Is even more preferable. By satisfying the above range, the balance between tensile elongation at break, toughness value and heat resistance, and water absorption reducing effect can be preferably achieved.

The Hansen solubility parameter of [A2] in the present invention is 9.0 to 9.8 (cal / cm ³ ) ^0.5 . If the Hansen solubility parameter of [A2] is less than 9.0 (cal / cm ³ ) ^0.5 , the heat resistance is insufficient, and if it exceeds 9.8 (cal / cm ³ ) ^0.5 , the water absorption reducing effect is insufficient. do.

Here, the Hansen solubility parameter (HSP) is a kind of dissolution parameter represented by three components, a dispersion force component (δ _d ), a polar component (δ _p ), and a hydrogen bond component (δ _h ). HSP can be calculated from the following formula (1), and the unit can be converted into SI unit system according to 1 (cal / cm ³ ) ^0.5 = 2.05 (MPa) ^0.5 .

HSP is a parameter that serves as a measure of affinity between substances, and it is empirically known that the smaller the difference between the two components of HSP, the higher the compatibility. In the present invention, the water-absorbing product of the cured epoxy resin is contained by containing an aliphatic epoxy resin having an HSP farther from the HSP of water and having low compatibility with water, that is, an aliphatic epoxy resin having higher hydrophobicity. Was effectively reduced.

The HSP can be uniquely calculated from the chemical structure of the component at 25 ° C. by using the computer software Hansen Solubility Parameter in Practice (HSPiP) (http://www.hansen-solubility.com). .. In the present invention, the HSP of [A2] is referred to as HSPiPver. It was calculated using 5.0.06 (a product sold by Video Studio Question Co., Ltd.).

The component [B] in the present invention is a carboxyl group-terminated butadiene nitrile rubber. By blending the component [B] into the epoxy resin composition, the toughness value of the cured epoxy resin can be effectively increased.

Commercially available products of such component [B] include "Hypro" (registered trademark) 1300X31, "Hypro" (registered trademark) 1300X13, "Hypro" (registered trademark) 1300X13NA, and "Hypro" (registered trademark) 1300X8 (hereinafter, CVC). (Manufactured by Thermoset Specialties) and the like can be used.

The component [C] in the present invention is a core-shell type rubber particle. By containing the component [C] in the epoxy resin composition, the toughness value can be increased without lowering the heat resistance of the cured epoxy resin.

Here, the core-shell type rubber particles are particles in which the shell component is modified on the surface of the particulate core component, and are particles in which a part or the whole of the surface of the core component is coated with the shell component. The components of the core and shell components are not particularly limited, and may have core and shell components.

Commercially available products of such component [C] include "Kaneace" (registered trademark) MX-125, "Kaneace" (registered trademark) MX-150, "Kaneace" (registered trademark) MX-154, and "Kaneace" (registered trademark). ) MX-257, "Kaneace" (registered trademark) MX-267, "Kaneace" (registered trademark) MX-416, "Kaneace" (registered trademark) MX-451, "Kaneace" (registered trademark) MX-EXP (HM5) ) (Above, manufactured by Kaneka Co., Ltd.), "PARALOID" (registered trademark) EXL-2655, EXL-2668 (above, manufactured by Dow Chemical) and the like can be used.

The epoxy resin composition in the present invention preferably contains 4 to 25 parts by mass of the component [C] with respect to 100 parts by mass of the total epoxy component in the epoxy resin composition. By satisfying the above range, excellent tensile elongation at break and improvement of toughness value can be obtained, and the fracture strength and fatigue characteristics of the fiber-reinforced composite material can be made particularly excellent.

Further, the mass ratio of the content of the component [B] to the content of the component [C] (content of the component [B] / content of the component [C]) may be 0.1 to 0.8. preferable. By satisfying the above range, the effect of improving the tensile elongation at break and the toughness value tends to be excellent.

The epoxy resin composition in the present invention needs to contain all of the component [A1], the component [A2], the component [B], and the component [C]. By including all of the component [A2], the component [B], and the component [C], the specific tensile elongation at break is achieved as compared with the case where each component is used alone or the two components are used in combination. The effect of improving the toughness value can be obtained. The reason why such an effect is obtained is not clear, but it is because the different tensile elongation at break and the mechanism for improving the toughness value of the components [A2], [B], and [C] work in concert. I'm guessing there is.

Further, by containing the component [A1] in addition to the component [A2], the component [B], and the component [C] within a range that does not impair the above-mentioned effect, in addition to the above-mentioned effect of improving the tensile elongation at break and the toughness value. Therefore, the price, mechanical properties, and heat resistance can be made suitable as a matrix resin for tough prepreg.

The component [D] in the present invention is dicyandiamide. Dicyanodiamide is a compound represented by the chemical formula (H ₂ N) ₂ C = N—CN, and is excellent in that it can impart high mechanical properties and heat resistance to an epoxy resin cured product obtained by using it as a curing agent. It is widely used as a curing agent for epoxy resins. Examples of commercially available dicyandiamides include DICY7T and DICY15 (all manufactured by Mitsubishi Chemical Corporation).

Since dicyandiamide is considered to be capable of reacting with epoxy groups at sites other than its own four active hydrogens, in the present invention, dicyandiamide is treated as reacting with seven epoxy groups during the curing reaction. That is, the apparent active hydrogen equivalent of dicyandiamide was 12 g / eq. Treat as.

The epoxy resin composition used for the tow preg of the present invention needs to contain an aromatic urea as a component [E]. By using the component [E] in combination with the component [D], the balance between the viscosity of the epoxy resin composition over time and the curing rate can be improved. Here, the aromatic urea refers to a compound having a structure in which a urea group is bonded to an aromatic ring, and specifically, 3- (3,4-dichlorophenyl) -1,1-dimethylurea (DCMU), 3 -(4-Chlorophenyl) -1,1-dimethylurea, phenyldimethylurea (PDMU), 2,4-toluenebis (3,3-dimethylurea) (TBDMU) and the like can be mentioned. These may be used alone or may be appropriately mixed and used.
Commercially available products of such component [E] include DCMU99 (DCMU, manufactured by Hodogaya Chemical Industry Co., Ltd.), "Omicure (registered trademark)" 24 (TBDMU, manufactured by Chori GLEX Co., Ltd.), and "Dyhard (registered trademark)" UR505 (registered trademark). 4,4'-Methylenebis (phenyldimethylurea), manufactured by AlzChem) and the like can be mentioned.

Above all, it is preferable to use TBDMU as the component [E] in the present invention. By using the component [D] in combination with TBDMU, it is possible to further enhance the quick-curing property while maintaining excellent storage stability.

In the present invention, the ratio of the number of moles of the component [D] to the number of moles of the urea group of the component [E] needs to be 2.0 to 9.0.

By satisfying the above range, the tensile elongation at break, the toughness value, the heat resistance, the water resistance, and the curing rate can be made excellent.

The epoxy resin composition of the present invention preferably contains the component [D] in an amount of 0.7 to 1.2 equivalents, more preferably 0.7 to 1.0 equivalents, and more preferably 0.7 to 1.0 equivalents with respect to the epoxy resin. Most preferably, it contains 0.9 equivalents.

The ratio of the number of moles of all epoxy groups in the epoxy resin composition to the number of moles of urea groups of the component [E] is preferably 20 to 50, more preferably 20 to 40.

By satisfying the above range of the contents of the component [D] and the component [E] while satisfying the condition [b], the tensile elongation at break, the toughness value, the heat resistance, the water resistance, and the curing rate can be made excellent. ..

In the present invention, by containing 5 to 40 parts by mass of the dicyclopentadiene type epoxy resin (component [A3]) in 100 parts by mass of the total epoxy component, the epoxy resin cured product does not significantly increase the viscosity of the epoxy resin composition. The heat resistance can be improved, and it can be more preferably used as a matrix resin for tow prepreg. A more preferable content of the dicyclopentadiene type resin is 5 to 30 parts by mass. By satisfying the above range, the balance between the viscosity and the effect of improving heat resistance becomes better.

Commercially available products of such component [A3] include "EPICLON" (trademark registration) HP-7200L, "EPICLON" (trademark registration) HP-7200, "EPICLON" (trademark registration) HP-7200H, and "EPICLON" (trademark registration). ) HP-7200HH, "EPICLON" (registered trademark) HP-7200HHH (all manufactured by DIC Co., Ltd.) and the like.

By blending an antifoaming agent with the epoxy resin composition of the present invention, it is possible to suppress the generation of foam when producing a fiber-reinforced composite material and improve the appearance quality. Above all, a silicon-free polymer-based defoaming agent is preferable because it can greatly suppress the generation of bubbles. Examples of commercially available products of such a silicon-free polymer-based defoaming agent include "BYK" (registered trademark) 1788, 1790, 1791, A535 (all manufactured by Big Chemie Japan Co., Ltd.) and the like.

In the present invention, as the component [A], an epoxy resin different from the components [A1] to [A3] may be used as long as the effect of the present invention is impaired. Specific examples thereof include an aniline type epoxy resin, a diaminodiphenylmethane type epoxy resin, a diaminodiphenyl sulfone type epoxy resin, a phenol novolac type epoxy resin, and a xylenediamine type epoxy resin. These may be used alone or in combination of two or more.

Examples of commercially available aniline-type epoxy resins include GAN (N, N-diglycidyl aniline) and GOT (N, N-diglycidyl-o-toluidine) (all manufactured by Nippon Kayaku Co., Ltd.).

Commercially available products of the above diaminodiphenylmethane type epoxy resin include "Sumiepoxy" (registered trademark) ELM434, ELM434VL (all manufactured by Sumitomo Chemical Corporation), YH434L (manufactured by Nippon Steel & Sumitomo Metal Corporation), and "jER" (registered). Trademarks) 604 (manufactured by Mitsubishi Chemical Corporation), "Araldite" (registered trademark) MY720, MY721 (all manufactured by Huntsman Advanced Materials) and the like can be mentioned.

Examples of commercially available products of the diaminodiphenyl sulfone type epoxy include TG3DAS (manufactured by Konishi Chemical Industry Co., Ltd.).

Examples of commercially available phenol novolac type epoxy resins include "jER" (registered trademark) 152, 154, 180S (all manufactured by Mitsubishi Chemical Corporation).

Examples of commercially available products of the xylene diamine type epoxy resin include TETRAD-X (manufactured by Mitsubishi Gas Chemical Company, Inc.).

The viscosity of the epoxy resin composition in the present invention at 25 ° C. is preferably 1 to 150 Pa · s, more preferably 3 to 50 Pa · s. When the viscosity satisfies the above range, the resin impregnation property into the reinforcing fiber is further improved, and it is not necessary to install a special heating mechanism or dilute with an organic solvent.

Machines such as a kneader, a planetary mixer, a three-roll and a twin-screw extruder may be used for preparing the epoxy resin composition of the present invention. If uniform kneading is possible, it may be mixed by hand using a beaker and a spatula.

The epoxy resin composition of the present invention can be used as an intermediate base material which is compositely integrated with the reinforcing fiber. Examples of the form of the intermediate base material include prepreg, slit tape, and tow prepreg. Above all, the epoxy resin composition of the present invention is suitably used for a tow prepreg obtained by impregnating a reinforcing fiber composed of 1,000 to 70,000 filaments with a matrix resin.

The tow prepreg in the present invention can be produced by various known methods. For example, a method of impregnating an epoxy resin composition while immersing reinforcing fibers in a resin bath whose viscosity has been reduced by heating without using an organic solvent, or applying the epoxy resin composition on a rotating roll or a release paper. It can be manufactured by a method such as filming, then transferring to one side or both sides of the reinforcing fiber, and then pressurizing and impregnating the fiber by passing it through a bending roll or a pressure roll.

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

The fiber-reinforced composite material of the present invention is obtained by curing the above-mentioned tow prepreg. For example, it can be obtained by wrapping a tow prepreg around a mandrel, a liner, or the like and heat-curing it. In the production of a fiber-reinforced composite material using a liner, the liner is composed of a liner, a cured epoxy resin covering the liner, and a reinforcing fiber. The epoxy resin composition of the present invention is used for general industrial applications such as a pressure vessel, which is required to have long-term durability and durability under high temperature and high humidity conditions by taking advantage of its excellent deformation ability, fracture toughness, water resistance and heat resistance. Suitable for use in.

Examples are shown below and the present invention will be described in more detail, but the present invention is not limited to the description of these examples.

The components used in this embodiment are as follows.

<Material used>
-Ingredient [A1]: Bisphenol type epoxy resin "jER" (registered trademark) 828 (manufactured by Mitsubishi Chemical Corporation).

-Ingredient [A2]: Bifunctional aliphatic epoxy resin "Denacol" (registered trademark) EX-212 (HSP = 9.4 (cal / cm ³ ) ^0.5 ),
"Denacol" (registered trademark) EX-216 (HSP = 9.6 (cal / cm ³ ) ^0.5 ),
"Denacol" (registered trademark) EX-211 (HSP = 9.3 (cal / cm ³ ) ^0.5 ) (all manufactured by Nagase ChemteX Corporation).

-Ingredient [A3]: Dicyclopentadiene type epoxy resin "EPICLON" (trademark registration) HP-7200L (manufactured by DIC Corporation).

-Ingredient [A4]: Aliphatic epoxy resin "Denacol" (registered trademark) EX-821 (HSP = 9.9 (cal / cm ³ ) ^0.5 ) other than ingredient [A2],
"Denacol" (registered trademark) EX-820 (HSP = 10.5 (cal / cm ³ ) ^0.5 ) (all manufactured by Nagase ChemteX Corporation)
DOP-DEP (HSP = 8.8 (cal / cm ³ ) ^0.5 ) (manufactured by Yokkaichi Chemical Co., Ltd.).

-Component [B]: Carboxyl group-terminated butadiene nitrile rubber "Hypro" (registered trademark) 1300X13 (manufactured by CVC Thermoset Specialties).

-Component [C]: Core-shell rubber type particles "Kaneace" (registered trademark) MX-150 (bisphenol A type epoxy resin 60% by mass and butadiene-based core-shell type rubber particles 40% by mass) (manufactured by Kaneka Co., Ltd.).

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

-Ingredient [E]: Curing accelerator "Omicure" (registered trademark) 24 (manufactured by PTI Japan Co., Ltd.).

-Defoaming agent "BYK" (registered trademark) 1790 (manufactured by Big Chemie Japan Co., Ltd.).

<Preparation method of epoxy resin composition>
A predetermined amount of the component [A] and other epoxy resin components were added to the stainless beaker, the temperature was raised to 100 ° C., and the mixture was appropriately kneaded until the components were compatible. After lowering the temperature to 60 ° C., components [B] to [E] and other components such as additives were added and kneaded for 10 minutes. Then, the epoxy resin composition was obtained by vacuum defoaming for 5 minutes. The composition of the epoxy resin is as shown in Tables 1 to 3.

<Evaluation method of tensile elongation at break of cured epoxy resin>
The uncured epoxy resin composition obtained according to the above <Method for preparing an epoxy resin composition> was placed at 150 ° C. in a mold set to a thickness of 2 mm with a 2 mm thick “Teflon” (registered trademark) spacer. The resin was cured at the same temperature for 1 hour to obtain a resin cured plate having a thickness of 2 mm. The obtained cured resin plate was processed into a 1BA type dumbbell shape according to JIS K7161 (1994). Using an Instron universal testing machine (manufactured by Instron), the distance between chucks was set to 58 mm, a resin tensile test was carried out at a test speed of 1 mm / min, and the tensile elongation at break was measured. At this time, the average value of the values measured with the number of samples n = 5 was adopted.

<Epoxy resin composition curing time evaluation method>
2 mL of the uncured epoxy resin composition obtained according to the above <method for preparing an epoxy resin composition> was allowed to stand on a micropress heated to 150 ° C. in advance, and a cure monitor LT-451 (manufactured by Lambient Technologies) was placed. Ion viscosity was measured using. The ionic viscosity of the epoxy resin composition takes a minimum value at the start of curing, increases with the progress of the curing reaction, and then saturates with the completion. In the present invention, the measurement was continued for 1 hour from the time when the rate of change in ionic viscosity became 0 for the first time. After the measurement, the cure index (Cd) was calculated from the measured value of the ionic viscosity according to the ASTM E2039 standard, and the time until the Cd reached 95% was adopted as the curing time.

<Epoxy resin cured product toughness value evaluation method>
The uncured epoxy resin composition obtained according to the above <Method for preparing an epoxy resin composition> was placed at 150 ° C. in a mold set to a thickness of 6 mm with a spacer made of 6 mm thick "Teflon" (registered trademark). The resin was cured at the same temperature for 1 hour to obtain a resin cured plate having a thickness of 6 mm. The obtained cured resin plate was processed into the shape of the test piece described in ASTM D5045-99, and then the SENB test was carried out according to ASTM D5045-99. At this time, the number of samples was set to n = 15, and the average value thereof was adopted as the toughness value.

<Measurement method of glass transition point temperature>
The uncured epoxy resin composition obtained according to the above <Method for preparing an epoxy resin composition> was placed at 150 ° C. in a mold set to a thickness of 2 mm with a 2 mm thick “Teflon” (registered trademark) spacer. The resin was cured at the same temperature for 1 hour to obtain a resin cured plate having a thickness of 2 mm. The obtained cured resin plate was processed to a length of 45 mm and a width of 12.7 mm, and vacuum dried at 60 ° C. for 24 hours. Then, the torsional dynamic viscoelasticity of the dried resin cured plate was measured using ARES-G2 (manufactured by TA Instruments) under the following conditions.
Measurement temperature range: 40 ° C to 200 ° C
Temperature rise rate: 5 ° C / min Distortion: 0.1%
Frequency: 6.28 rad / sec The glass transition temperature was determined from the change curve of the storage elastic modulus obtained by measurement according to JIS K7095 (2012). At this time, the number of samples was set to n = 2, and the average value thereof was adopted as the glass transition point temperature.

<Measuring method of viscosity of epoxy resin composition at 25 ° C>
E-type viscometer (manufactured by Toki Sangyo Co., Ltd., TVE-) equipped with a standard cone rotor (3 ° x R9.7) according to "Conical-Viscosity measurement method using a flat plate type rotational viscometer" in JIS Z8803 (2011). 22HT) was used, and the measurement was performed at a rotation speed of 5 rpm with the actual temperature of the measuring unit set to 25 ° C. The value 5 minutes after the start of measurement was adopted as the viscosity.

The viscosity of the epoxy resin composition at 25 ° C. 5 minutes after the preparation according to the above <method for preparing the epoxy resin composition> was defined as the initial viscosity (η ₀ ) of the epoxy resin composition.

<Calculation method of thickening ratio when heated at 50 ° C for 24 hours>
The uncured epoxy resin composition obtained according to the above <Method for preparing an epoxy resin composition> was allowed to stand in an oven set at 50 ° C. for 24 hours and heated. Then, the viscosity (η ₂₄ ) of the heated epoxy resin composition was measured according to the above <method for measuring the viscosity of the epoxy resin composition at 25 ° C.>. The thickening ratio was calculated according to the formula (2).

<Epoxy resin cured product water absorption evaluation method>
The uncured epoxy resin composition obtained according to the above <Method for preparing an epoxy resin composition> was placed at 150 ° C. in a mold set to a thickness of 2 mm with a 2 mm thick “Teflon” (registered trademark) spacer. The resin was cured at the same temperature for 1 hour to obtain a resin cured plate having a thickness of 2 mm. Then, the obtained cured resin plate was processed into a size of 60 mm in length and 10 mm in width, vacuum dried at 60 ° C. for 24 hours, and the mass ( _before W) of the dried resin cured plate before the water absorption treatment was measured. did. The dried resin cured plate was allowed to stand for 7 days at a temperature of 85 ° C. and a humidity of 95% for water absorption treatment, and then the mass ( _after W) of the resin cured plate after the water absorption treatment was measured. The water absorption rate of the resin cured plate was calculated according to the formula (3) using _before W and _after W. At this time, the number of samples was set to n = 6, and the average value was taken as the mass of the resin cured plate.

(Example 1)
73 parts by mass of "jER" (registered trademark) 828 as component [A1], 10 parts by mass of "Denacol" (registered trademark) EX-212 as component [A2], and "Hypro" (registered trademark) as component [B]. 3.1 parts by mass of 1300X13, 28 parts by mass of "Kaneace" (registered trademark) MX-150 as component [C], 5.4 parts by mass of DICY7 as component [D], and "Omicure" as component [E] ( Using 2.3 parts by mass of Registered Trademark) 24, an epoxy resin composition was prepared according to the above <Method for preparing an epoxy resin composition>.

The initial viscosity and curing rate of the prepared epoxy resin composition at 25 ° C. were evaluated according to the above <method for measuring the viscosity of the epoxy resin composition at 25 ° C.> and <method for evaluating the curing time of the epoxy resin composition>. The initial viscosity was 8.3 Pa · s and the curing time was 33 minutes, which was suitable as an epoxy resin composition for tow prepreg.

With respect to this epoxy resin composition, according to the above <method for evaluating the water absorption of the cured epoxy resin>, <method for evaluating the tensile elongation at break of the cured epoxy resin>, and <method for evaluating the toughness value of the cured epoxy resin>. When the water absorption rate, the tensile elongation at break and the toughness value were evaluated, the water absorption rate was 4.2%, the tensile elongation at break was 11%, and the fracture toughness value was 2.2 MPa · m ^0.5 , all of which were good. rice field.

The heat resistance was also evaluated according to the above <method for measuring the glass transition temperature>, and the glass transition temperature was as good as 131 ° C.

(Examples 2 to 9)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the resin compositions were changed as shown in Table 1. As for the evaluation results, as shown in Table 1, good results were obtained in all the items.

(Example 10)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the resin compositions were changed as shown in Table 2. As for the evaluation results, as shown in Table 2, good results were obtained in all the items. However, since the blending amount of the component [A2] was less than 3 parts by mass, the balance between the tensile elongation at break and the toughness value was superior in Examples 1 to 9.

(Example 11)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the resin compositions were changed as shown in Table 2. As for the evaluation results, as shown in Table 2, good results were obtained in all the items. However, since the blending amount of the component [A2] was larger than 18 parts by mass, the balance between the tensile elongation at break, the toughness value, and the glass transition point temperature was better in Examples 1 to 10.

(Example 12)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the resin compositions were changed as shown in Table 2. As for the evaluation results, as shown in Table 2, good results were obtained in all the items. However, since the blending amount of the component [C] was larger than 25 parts by mass, the viscosity at 25 ° C. was 42 Pa · s, which was larger than that of Examples 1 to 11.

(Example 13)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the resin compositions were changed as shown in Table 2. As for the evaluation results, as shown in Table 2, good results were obtained in all the items. However, since the blending amount of the component [C] was less than 4 parts by mass, the balance between the tensile elongation at break and the toughness value was superior in Examples 1 to 12.

(Example 14)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the resin compositions were changed as shown in Table 2. As for the evaluation results, as shown in Table 2, good results were obtained in all the items.

(Examples 15 and 16)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the resin compositions were changed as shown in Table 2. As for the evaluation results, as shown in Table 2, good results were obtained in all the items. In particular, the balance between the glass transition point temperature and the viscosity was superior to that of Examples 1 to 14, indicating the effect of the dicyclopentadiene type epoxy resin.

(Example 17)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the resin compositions were changed as shown in Table 2. As for the evaluation results, as shown in Table 2, good results were obtained in all the items. However, since the blending amount of the dicyclopentadiene type epoxy resin was less than 5 parts by mass, the effect of improving the glass transition point temperature was smaller than that of Examples 15 and 16.

(Example 18)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the resin compositions were changed as shown in Table 2. As for the evaluation results, as shown in Table 2, good results were obtained in all the items. However, since the amount of the dicyclopentadiene type epoxy resin compounded is more than 30 parts by mass, the effect of improving the glass transition temperature is large, but the initial viscosity at 25 ° C. is as large as 74 Pa · s.

(Example 19)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the resin compositions were changed as shown in Table 2. As for the evaluation results, as shown in Table 2, good results were obtained in all the items. However, since the content of the dicyclopentadiene type epoxy resin is more than 40 parts by mass, the effect of improving the glass transition temperature is the greatest, but the viscosity at 25 ° C. becomes too large at 153 Pa · s, and the tow prepreg Heating was required during production.

(Comparative Example 1)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the component [A2] was not contained. As shown in Table 3, the evaluation results were insufficient with a tensile elongation at break of 7.7% and a toughness value of 1.8 MPa · m ^0.5 .

(Comparative Examples 2 and 3)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that an aliphatic epoxy resin having an HSP of 9.8 ( ^cal / cm ³ ) or more was blended. As a result of the evaluation, as shown in Table 3, the water absorption rate increased remarkably.

(Comparative Example 4)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that an aliphatic epoxy resin having an HSP of less than 9.0 ( ^cal / cm ³ ) was blended. As a result of the evaluation, as shown in Table 3, the glass transition temperature was significantly lowered.

(Comparative Example 5)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the component [B] was not contained. As shown in Table 3, the evaluation results were insufficient with a tensile elongation at break of 7.4% and a toughness value of 1.6 MPa · m ^0.5 .

(Comparative Example 6)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the component [C] was not contained. As shown in Table 3, the evaluation results were insufficient with a tensile elongation at break of 5.3% and a toughness value of 1.8 MPa · m ^0.5 .

(Comparative Example 7)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the ratio of the number of moles of the component [D] to the number of moles of the urea group of the component [E] was larger than 9.0. As shown in Table 3, the evaluation results were good, with a tensile elongation at break of 12% and a toughness value of 2.3 MPa · m ^0.5 . However, the water absorption rate was 5.8%, which was significantly worse than that of the examples.

(Comparative Example 8)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the number of moles of the epoxy group was larger than 9.0 with respect to the number of moles of the urea group of the component [E]. As shown in Table 3, the evaluation results were good, with a tensile elongation at break of 11% and a toughness value of 2.1 MPa · m ^0.5 . However, the curing time was 54 minutes, which was significantly worse than that of the examples.

(Comparative Example 9)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the number of moles of the epoxy group was smaller than 2.0 with respect to the number of moles of the urea group of the component [E]. As shown in Table 3, the evaluation results showed a tensile elongation at break of 7.2%, a toughness value of 1.6 MPa · m ^0.5 , and a glass transition point temperature of 113 ° C., which were significantly worse than those of Examples. did.

(Comparative Example 10)
An epoxy resin composition was prepared and evaluated by the same method as in Example 1 except that the number of moles of the epoxy group was smaller than 2.0 with respect to the number of moles of the urea group of the component [E]. As shown in Table 3, the evaluation results showed that the tensile elongation at break was 7.4%, the toughness value was 1.7 MPa · m ^0.5 , the glass transition temperature was 114 ° C., and the curing time was 47 minutes. It was significantly worse than that.

The unit of each component in the table is a mass part.

The epoxy resin composition of the present invention provides a cured epoxy resin composition having both deformability and fracture toughness at a high level, excellent heat resistance, and low water absorption. Therefore, the fiber-reinforced composite material made of the epoxy resin composition is excellent not only in long-term durability such as fracture strength and fatigue characteristics, but also in durability under high temperature and high humidity conditions. In addition, the epoxy resin composition of the present invention is also excellent in quick-curing property, so that the productivity of the fiber-reinforced composite material can be increased. Such a fiber-reinforced composite material can be suitably used for general industrial applications such as pressure vessels.

Claims (10)

An epoxy resin composition containing all of the following components [A] to [E] and satisfying the conditions [a] and [b].
[A]: Epoxy resin [A1] including at least [A1] and [A2]: Bisphenol type epoxy resin [A2]: Represented by the following chemical formula (I), and X in the chemical formula (I) is as follows ( Bifunctional aliphatic epoxy resin satisfying either 1) or (2)

(1) Linear or branched alkylene having 4 to 10 carbon atoms (2) Cycloalkylalkylene [B] having 4 to 10 carbon atoms: carboxyl group-terminated butadiene nitrile rubber [C]: core-shell type rubber particles [D]: dicyandiamide [E]: Aromatic urea [a]: Hansen solubility parameter of component [A2] is 9.0 to 9.8 (cal / cm ³ ) ^0.5 .
[B]: The ratio of the number of moles of the component [D] to the number of moles of the urea group of the component [E] is 2.0 to 9.0. The epoxy resin composition according to claim 1, which contains 3 to 18 parts by mass of the component [A2] in 100 parts by mass of the total epoxy resin component in the epoxy resin composition. The epoxy resin composition according to claim 1 or 2, which contains 4 to 25 parts by mass of the component [C] with respect to 100 parts by mass of the total epoxy resin component in the epoxy resin composition. The epoxy resin composition according to any one of claims 1 to 3, which has a viscosity at 25 ° C. of 1 to 150 Pa · s. The epoxy resin composition according to any one of claims 1 to 4, wherein the thickening ratio at 25 ° C. after heating at 50 ° C. for 24 hours is 1 time or more and 2 times or less. The epoxy resin composition according to any one of claims 1 to 5, which comprises a defoaming agent. The epoxy resin composition according to any one of claims 1 to 6, which contains 5 to 40 parts by mass of a dicyclopentadiene type epoxy resin (component [A3]) in 100 parts by mass of the total epoxy resin component in the epoxy resin composition. .. The epoxy resin composition according to any one of claims 1 to 7, which contains 2,4-toluenebis (3,3-dimethylurea) as the component [E]. A tow prepreg obtained by impregnating a reinforcing fiber with the epoxy resin composition according to any one of claims 1 to 8. A fiber-reinforced composite material obtained by curing the tow prepreg according to claim 9.