Epoxy resin composition, cured resin, fiber-reinforced composite material, and method for producing the same

Abstract

To provide an epoxy resin composition having a small coefficient of thermal expansion in its cured resin and an excellent balance of elastic modulus under humid heat, heat resistance in a moist state, and fracture toughness, and a fiber-reinforced composite material made of the epoxy resin composition.SOLUTION: The epoxy resin composition of the present invention comprises the following components [A], [B], and [C]: [A]: tetrafunctional glycidylamine-type epoxy resin, [B]: alkylbenzene diamine and / or methylenebis aniline, and [C]: silica particles.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin composition that is preferably used for aerospace components and general industrial applications, a cured resin product, a fiber-reinforced composite material using the same, and a method for producing the same. [Background technology]

[0002] Epoxy resin compositions, which have excellent heat resistance, adhesive properties, and mechanical strength, are widely used as matrix resins in fiber-reinforced composite materials. Fiber-reinforced composite materials are produced by integrating reinforcing fibers and matrix resins. Manufacturing methods include lamination molding of prepregs in which reinforcing fibers and matrix resins have been impregnated, and injecting a low-viscosity matrix resin into a shaped reinforcing fiber substrate and curing the resulting material. Generally, methods using prepregs are widely used in the industrial and aircraft fields because they exhibit high mechanical properties. However, they have the disadvantage of requiring time-consuming manufacturing processes, such as the preparation and shaping of the prepregs.

[0003] In recent years, there has been an increasing demand for high productivity in structural applications such as aircraft and automobiles, and there is a need for technology that can rapidly produce large composite material components and obtain fiber-reinforced composite materials with high mechanical properties and heat resistance. Therefore, there is a growing demand for fiber-reinforced composite materials that can be molded using injection molding methods such as resin transfer molding (RTM) and that exhibit excellent properties.

[0004] In the injection molding method, two-component epoxy resin compositions are often used from the perspective of molding processability. A two-component epoxy resin composition is an epoxy resin composition that is composed of an epoxy base liquid containing an epoxy resin as its main component and a hardener liquid containing a hardener as its main component, and is obtained by mixing the two liquids, the epoxy base liquid and the hardener liquid, immediately before use. In contrast, an epoxy resin composition in which all components, including the base resin and hardener, are mixed into one is called a one-component epoxy resin composition.

[0005] Fiber-reinforced composite materials used as primary structural materials for aircraft applications, etc., require a good balance of elastic modulus under wet heat, heat resistance, fracture toughness, and dimensional stability. One method for increasing elastic modulus under wet heat and heat resistance is to incorporate a large amount of multifunctional epoxy resins. However, this method results in an excessively high crosslink density in the cured resin, which reduces fracture toughness and impact resistance of the fiber-reinforced composite material. Another problem is that the coefficient of linear thermal expansion increases, resulting in poor dimensional stability.

[0006] Patent Document 1 discloses a technique for reducing the water absorption rate of a cured epoxy resin by incorporating a dicyclopentadiene-type epoxy resin and a trifunctional liquid epoxy resin.

[0007] Patent Document 2 discloses a technique for obtaining a cured epoxy resin product with high fracture toughness by using a thermoplastic resin and core-shell rubber particles in combination at a specific ratio. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-291093 [Patent Document 2] Patent No. 5808057 Summary of the Invention [Problem to be solved by the invention]

[0009] The cured resin product using the epoxy resin composition described in Patent Document 1 had low water absorption but insufficient wet heat elastic modulus. Furthermore, there is no suggestion or mention of the linear thermal expansion coefficient of the epoxy resin composition.

[0010] The cured resin product using the epoxy resin composition described in Patent Document 2 has excellent fracture toughness but an insufficient wet heat elastic modulus. Furthermore, there is no suggestion or mention of the linear thermal expansion coefficient of the epoxy resin composition.

[0011] An object of the present invention is to provide an epoxy resin composition, a cured resin product, and a fiber-reinforced composite material using the same, which overcome the drawbacks of the prior art. [Means for solving the problem]

[0012] As a result of extensive research into solving the above problems, the present inventors have completed the invention having the following configuration. [1] An epoxy resin composition comprising the following components [A], [B], and [C]. [A]: tetrafunctional glycidylamine epoxy resin [B]: alkylbenzenediamine and / or methylenebisaniline [C]: Silica particles [2] The epoxy resin composition according to [1], wherein the silica particles have an average particle size of 1 μm or less. [3] The epoxy resin composition according to [1] or [2], containing 1 part by mass or more and 40 parts by mass or less of component [C] per 100 parts by mass of the total epoxy resin. [4] The epoxy resin composition according to any one of [1] to [3], which contains an aniline-type epoxy resin represented by formula (I) as component [D].

[0013] [ka]

[0014] (In formula (I), R 1 and R 2 R represents at least one selected from the group consisting of aliphatic hydrocarbon groups having 1 to 4 carbon atoms. 1 and R 2 When there are multiple, they may be the same or different. n is an integer of 0 to 4, and m is an integer of 0 to 5. X represents -O- or -S-. [5] The epoxy resin composition according to [4], wherein the component [D] is contained in an amount of 10% by mass or more and 50% by mass or less, based on 100% by mass of the total epoxy resin. [6] The epoxy resin composition according to any one of [1] to [5], comprising, as component [E], 1 part by mass or more and 10 parts by mass or less of core-shell type rubber particles per 100 parts by mass of the total epoxy resin. [7] The epoxy resin composition according to any one of [1] to [6], wherein, relative to 100% by mass of the total epoxy resins, the epoxy resin composition contains, as component [F], 10% by mass or more and 50% by mass or less of at least one solid epoxy resin selected from the group consisting of dicyclopentadiene-type epoxy resins, biphenyl-type epoxy resins, phenol aralkyl-type epoxy resins, and naphthalene-type epoxy resins. [8] The epoxy resin composition according to any one of [1] to [7], which contains alkylbenzenediamine and methylenebisaniline as component [B]. [9] The epoxy resin composition according to any one of [1] to [7], which contains only alkylbenzenediamine as component [B].

[10] The epoxy resin composition according to any one of [1] to [9], which contains dimethylthiotoluenediamine as component [B].

[11] The epoxy resin composition according to any one of [1] to [8] and

[10] , which contains 4,4-methylenebis(isopropyl-6-methylaniline) as the component [B].

[12] The epoxy resin composition according to any one of [1] to

[11] , wherein the value (Mh / Me) obtained by dividing the total number of moles of active hydrogen contained in component [B] (Mh) by the total number of moles of active groups contained in all epoxy resins (Me) is 0.8 or more and 1.2 or less.

[13] A cured resin product obtained by thermally curing the epoxy resin composition according to any one of [1] to

[12] .

[14] A fiber-reinforced composite material comprising the cured resin according to

[13] and a reinforcing fiber substrate.

[15] The fiber-reinforced composite material according to

[14] , wherein the reinforcing fiber substrate is a carbon fiber substrate.

[16] A method for producing a fiber-reinforced composite material, comprising injecting the epoxy resin composition according to any one of [1] to

[12] into a reinforcing fiber substrate placed in a mold heated to 70°C or higher and 190°C or lower, allowing the composition to impregnate the substrate, and curing the composition in the mold.

[17] The method for producing a fiber-reinforced composite material according to

[16] , wherein the reinforcing fiber substrate is a carbon fiber substrate. [Effects of the Invention]

[0015] According to the present invention, there is provided an epoxy resin composition which can give a cured epoxy resin product having a high elastic modulus and fracture toughness under wet heat conditions and a low coefficient of linear thermal expansion. The epoxy resin composition of the present invention can also be suitably used for producing fiber-reinforced composite materials by injection molding. DETAILED DESCRIPTION OF THE INVENTION

[0016] The epoxy resin composition of the present invention contains, as essential components, a tetrafunctional glycidylamine-type epoxy resin as component [A], an alkylbenzenediamine and / or methylenebisaniline as component [B], and silica particles as component [C]. It also preferably contains an aniline-type epoxy resin represented by formula (I) as component [D], core-shell rubber particles as component [E], and at least one solid epoxy resin selected from the group consisting of dicyclopentadiene-type epoxy resins, biphenyl-type epoxy resins, phenol aralkyl-type epoxy resins, and naphthalene-type epoxy resins as component [F]. These components will now be described.

[0017] (Component [A]) The epoxy resin composition of the present invention must contain a tetrafunctional glycidylamine-type epoxy resin as component [A]. By including component [A], the cured resin obtained by curing the epoxy resin composition of the present invention exhibits high heat resistance and an excellent wet heat elastic modulus. Without component [A], the cured resin obtained by curing the epoxy resin composition will have insufficient heat resistance. Furthermore, component [A] preferably accounts for 20% to 80% by mass, more preferably 40% to 60% by mass, and even more preferably 40% to 50% by mass, of 100% by mass of all epoxy resins contained in the epoxy resin composition. Here, "20% to 80% by mass, based on 100% by mass of all epoxy resins contained in the epoxy resin composition of the present invention" means "20% to 80% by mass, based on 100% by mass of all epoxy resins contained in the epoxy resin composition of the present invention." The term "total epoxy resins" as used herein refers to all epoxy resin components contained in the epoxy resin composition of the present invention (the same applies hereinafter). By satisfying the above range, when the epoxy resin composition of the present invention is cured, an epoxy resin cured product having high heat resistance and at the same time a high elastic modulus under wet heat can be obtained. Therefore, by using the epoxy resin composition as a matrix resin, a fiber-reinforced composite material having excellent compressive strength under wet heat can be obtained.

[0018] Examples of such component [A] include tetraglycidyldiaminodiphenylmethane, tetraglycidyldiaminodiphenylsulfone, and the like.

[0019] Commercially available products of the above-mentioned tetraglycidyldiaminodiphenylmethane include "Sumiepoxy (registered trademark)" ELM-434, "Sumiepoxy (registered trademark)" ELM-434VL (both manufactured by Sumitomo Chemical Co., Ltd.), YH434L (manufactured by Nippon Steel Chemical & Material Co., Ltd.), "jER (registered trademark)" 604 (manufactured by Mitsubishi Chemical Corporation), "Araldite (registered trademark)" MY720, and "Araldite (registered trademark)" MY721 (all manufactured by Huntsman Japan Co., Ltd.).

[0020] Commercially available products of the above tetraglycidyldiaminodiphenyl sulfone include TG3DAS (manufactured by Konishi Chemical Industry Co., Ltd.).

[0021] (Component [B]) The component [B] in the present invention is an alkylbenzenediamine and / or methylenebisaniline.

[0022] Such alkylbenzenediamines are aromatic amine compounds having one or more alkyl groups and two amino groups on the benzene ring, and toluenediamines such as diethyltoluenediamine and dimethylthiotoluenediamine are preferably used. By using an alkylbenzenediamine as a curing agent for an epoxy resin, it is possible to obtain a cured resin product with an excellent elastic modulus while suppressing the viscosity of the epoxy resin composition in the resin injection process. Among these, dimethylthiotoluenediamine is particularly preferred because it can obtain a cured resin product with an excellent balance between elastic modulus and toughness.

[0023] Commercially available alkylbenzene diamines include jER Cure (registered trademark) WA (manufactured by Mitsubishi Chemical Corporation), Ethacure (registered trademark) 100 (manufactured by Albemarle), Heart Cure (registered trademark) 10 (manufactured by Kumiai Chemical Industry Co., Ltd.), Primacure (registered trademark) DETDA80 (manufactured by Prima), Ethacure (registered trademark) 300 (manufactured by Albemarle), and Heart Cure (registered trademark) 30 (manufactured by Kumiai Chemical Industry Co., Ltd.).

[0024] Such methylene bisaniline is an aromatic amine compound in which two aniline compounds are linked by a methylene bridge. Various substituents may be present on the benzene ring of each aniline compound. By using methylene bisaniline as a curing agent for epoxy resins, it is possible to obtain cured resins with low water absorption and excellent toughness.

[0025] Examples of such methylene bisanilines include 4,4-methylenebis(isopropyl-6-methylaniline) (M-MIPA), methylenebis(diethylaniline) (M-DEA), methylenebis(chlorodiethylaniline) (M-CDEA), methylene(methylethylaniline)-(chlorodiethylaniline) (M-MEACDEA), etc. Among these, 4,4-methylenebis(isopropyl-6-methylaniline) is particularly preferred because it can give a cured resin having an excellent balance between elastic modulus and toughness.

[0026] Commercially available products of such methylenebisaniline include MDA-220 (manufactured by Mitsui Chemicals, Inc.), "Primacure (registered trademark)" M-MIPA, "Primacure (registered trademark)" M-DEA, "Primacure (registered trademark)" M-CDEA, "Primacure (registered trademark)" M-DIPA (all manufactured by Prima), and "Kayahard (registered trademark)" AA(PT) (manufactured by Nippon Kayaku Co., Ltd.).

[0027] In the present invention, it is preferable that component [B] contains only an alkylbenzenediamine, and it is also preferable that component [B] contains an alkylbenzenediamine and methylenebisaniline.

[0028] The inclusion of only alkylbenzenediamine as component [B] in the present invention is preferred in that it is possible to obtain a cured resin product with an excellent elastic modulus while sufficiently suppressing the viscosity of the epoxy resin composition in the resin injection step.

[0029] On the other hand, the inclusion of alkylbenzenediamine and methylenebisaniline as component [B] in the present invention is preferable in that it makes it possible to obtain a cured resin product that has an excellent balance of elastic modulus, low water absorption, and toughness while suppressing the viscosity of the epoxy resin composition in the resin injection step.

[0030] In the present invention, component [B] is preferably liquid at 23° C. When component [B] is liquid, the viscosity of the epoxy resin composition of the present invention can be reduced, making it suitable for use in injection molding of fiber-reinforced composite materials.

[0031] (Component [C]) The epoxy resin composition of the present invention must contain silica particles as component [C]. By including component [C], it is possible to obtain a cured epoxy resin product that is excellent in elastic modulus and toughness and has a small coefficient of linear thermal expansion. Furthermore, by using component [C] in combination with component [B], it is possible to disperse component [C] well in the epoxy resin composition of the present invention, thereby obtaining a cured epoxy resin product that is even more excellent in elastic modulus and toughness and has a small coefficient of linear thermal expansion.

[0032] The average particle size of component [C] is preferably 1 μm or less, more preferably 0.5 μm or less, and even more preferably 0.2 μm or less. By satisfying the above range, particles are not filtered out in the reinforcing fiber substrate during the resin injection process, and a reinforced fiber composite material in which the particles are uniformly dispersed can be obtained. Furthermore, by making the average particle size of component [C] preferably 0.01 μm or more, more preferably 0.05 μm or more, an epoxy resin cured product with excellent toughness can be obtained. Furthermore, component [C] is preferably spherical because it has good fluidity during the resin injection process and is less likely to damage the reinforcing fibers.

[0033] Here, the average particle size of component [C] can be calculated by, for example, observing the cross section of a cured epoxy resin product using a scanning electron microscope or a transmission electron microscope, measuring the diameters of at least 50 particles, and averaging the measured diameters. If the particles are not perfectly circular in the above observation, i.e., if they are elliptical, the maximum diameter of the particles is taken as the particle size of the particles.

[0034] Furthermore, the content of component [C] is preferably 1 to 40 parts by mass, and more preferably 5 to 20 parts by mass, per 100 parts by mass of the total epoxy resin. By satisfying this range, it is possible to obtain a cured epoxy resin product that has excellent elastic modulus and toughness and a small coefficient of linear thermal expansion, while suppressing the viscosity of the epoxy resin composition.

[0035] The silica particles used as component [C] of the present invention are preferably treated with a surface treatment agent to enhance adhesion to epoxy resins. Silane coupling agents are preferred as surface treatment agents, and epoxysilanes, aminosilanes, and phenylsilanes are more preferred due to their high affinity and reactivity with epoxy resins.

[0036] Commercially available products of such component [C] include "Adma Fine (registered trademark)" SO-C1, "Adma Fine (registered trademark)" SO-C2, "Adma Fine (registered trademark)" SO-C4, "Admanano (registered trademark)" YA010C, "Admanano (registered trademark)" YA050C, "Admanano (registered trademark)" YC100C (all manufactured by Admatechs Co., Ltd.), "AEROSIL (registered trademark)" 50, "AEROSIL (registered trademark)" 200, "AEROSIL (registered trademark)" 300 (all manufactured by Nippon Aerosil Co., Ltd.), and Sciqas (manufactured by Sakai Chemical Industry Co., Ltd.).

[0037] (Component [D]) The epoxy resin composition of the present invention preferably contains an aniline-type epoxy resin represented by formula (I) as component [D].

[0038] [ka]

[0039] (In formula (I), R 1 and R 2 R represents at least one selected from the group consisting of aliphatic hydrocarbon groups having 1 to 4 carbon atoms. 1 and R 2When there are multiple, they may be the same or different. n is an integer of 0 to 4, and m is an integer of 0 to 5. X represents -O- or -S-.

[0040] By including component [D], it is possible to maintain the elastic modulus of the cured resin obtained by curing the epoxy resin composition of the present invention while lowering the rubber-state elastic modulus. Furthermore, component [D] preferably accounts for 10% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and 40% by mass or less, of 100% by mass of the total epoxy resin. By satisfying the above ranges, curing the epoxy resin composition of the present invention can produce a cured epoxy resin product that has high heat resistance and simultaneously a high elastic modulus under wet heat conditions.

[0041] Examples of such component [D] include diglycidyl-p-phenoxyaniline, diglycidyl-4-(4-methylphenoxy)aniline, diglycidyl-4-(4-tert-butylphenoxy)aniline, diglycidyl-4-(4-phenoxyphenoxy)aniline, etc. Among these, diglycidyl-p-phenoxyaniline (in formula (I), n = 0, m = 0, X = -O-) with a small molecular weight is preferably used in the resin injection process due to its low viscosity.

[0042] Commercially available products of such diglycidyl-p-phenoxyaniline include "TOREP (registered trademark)" A-204E (diglycidyl-p-phenoxyaniline) (manufactured by Toray Fine Chemicals Co., Ltd.).

[0043] (Component [E]) The epoxy resin composition of the present invention preferably contains core-shell rubber particles as component [E] in an amount of 1 to 10 parts by mass, and more preferably 3 to 6 parts by mass, per 100 parts by mass of the total epoxy resin. By containing component [E] in the above range, the fracture toughness can be increased without impairing the elastic modulus of the cured resin obtained by curing the epoxy resin composition of the present invention. Therefore, by using the epoxy resin composition of the present invention as a matrix resin, a fiber-reinforced composite material with improved compression properties and impact resistance can be obtained.

[0044] Commercially available products of component [E] include "Kane Ace (registered trademark)" MX-125, "Kane Ace (registered trademark)" MX-150, "Kane Ace (registered trademark)" MX-154, "Kane Ace (registered trademark)" MX-257, "Kane Ace (registered trademark)" MX-267, "Kane Ace (registered trademark)" MX-416, and "Kane Ace (registered trademark)" MX-451 (all manufactured by Kaneka Corporation), "PARALOID (registered trademark)" EXL-2655, and "PARALOID (registered trademark)" EXL-2668 (all manufactured by Dow Chemical Company), etc.

[0045] The fracture toughness value of the cured epoxy resin material of the present invention can be evaluated, for example, by the K1c value obtained from the SENB test described in ASTM D5045-99.

[0046] (Component [F]) The epoxy resin composition of the present invention preferably contains, as component [F], at least one solid epoxy resin selected from the group consisting of dicyclopentadiene-type epoxy resins, biphenyl-type epoxy resins, phenol aralkyl-type epoxy resins, and naphthalene-type epoxy resins, in an amount of 10 to 50 mass% and more preferably 20 to 40 mass% relative to 100 mass% of the total epoxy resins. By containing component [F] in the above range, the water absorption of the cured resin product obtained when the epoxy resin composition of the present invention is cured can be reduced, thereby increasing the wet heat modulus.

[0047] In addition, epoxy resins that can be used as component [F] and have a skeleton that can be classified as dicyclopentadiene-type epoxy resins, biphenyl-type epoxy resins, phenol aralkyl-type epoxy resins, or naphthalene-type epoxy resins, and that can also fall under component [A] or component [D], will be treated as component [A] or component [D], respectively.

[0048] As component [F], dicyclopentadiene-type epoxy resins and naphthalene-type epoxy resins are preferably used because they have an excellent balance between elastic modulus and toughness. In particular, dicyclopentadiene-type epoxy resins are more preferably used because they can improve the fracture toughness of the cured resin.

[0049] Commercially available dicyclopentadiene epoxy resins that can be used as component [F] include "EPICLON (registered trademark)" HP-7200L, "EPICLON (registered trademark)" HP-7200, "EPICLON (registered trademark)" HP-7200H, and "EPICLON (registered trademark)" HP-7200HH (all manufactured by DIC Corporation).

[0050] Commercially available biphenyl-type epoxy resins that can be used as component [F] include "jER (registered trademark)" YX-4000 (manufactured by Mitsubishi Chemical Corporation).

[0051] Commercially available phenol aralkyl epoxy resins that can be used as component [F] include NC-3000H, NC-3000, NC-3000L, NC-7000, NC-7300, NC-2000, and NC-2000L (all manufactured by Nippon Kayaku Co., Ltd.).

[0052] Commercially available naphthalene-type epoxy resins that can be used as component [F] include "EPICLON (registered trademark)" HP-4770 and "EPICLON (registered trademark)" HP-4700 (both manufactured by DIC Corporation).

[0053] The water absorption rate of the cured epoxy resin material of the present invention can be evaluated by, for example, immersing a test piece having a thickness of 2.0 mm, a width of 10 mm and a length of 60 mm in boiling water for 48 hours and measuring the difference in mass before and after immersion.

[0054] The value (Mh / Me) obtained by dividing the sum of the moles of active hydrogen (Mh) in component [B] contained in the epoxy resin composition of the present invention by the sum of the moles of active epoxy groups (Me) in all epoxy resins is preferably in the range of 0.8 to 1.2, more preferably in the range of 0.9 to 1.1. By achieving this range, the reaction between the epoxy resin and the curing agent occurs efficiently and the water absorption rate is reduced, resulting in a resin cured product obtained by curing the epoxy resin composition with a high wet heat modulus, and a fiber-reinforced composite material exhibiting superior wet heat compressibility can be obtained. In addition, the excellent heat resistance after humidification makes the composition suitable for use as a fiber-reinforced composite material for structural applications.

[0055] The sum of the moles of active epoxy groups (Me) of all epoxy resins is the sum of the values ​​obtained by dividing the mass of each epoxy resin by its epoxy equivalent, and is expressed by the following formula. Me = (mass of epoxy resin A / epoxy equivalent of epoxy resin A) + (mass of epoxy resin B / epoxy equivalent of epoxy resin B) + + (mass of epoxy resin Z / epoxy equivalent of epoxy resin Z).

[0056] The total number of moles of active hydrogen (Mh) in component [B] is the sum of the values ​​obtained by dividing the mass of each compound classified as alkylbenzenediamine or methylenebisaniline contained in the epoxy resin composition by its active hydrogen equivalent, and is expressed by the following formula: Mh = (mass of component [B]-A / active hydrogen equivalent of component [B]-A) + (mass of component [B]-B / active hydrogen equivalent of component [B]-B) + + (mass of component [B]-Z / active hydrogen equivalent of component [B]-Z).

[0057] The epoxy resin composition of the present invention has a flexural modulus (E 82) is the flexural modulus (E 23 ) has the characteristic that the degree of decline is small compared to E 82 and E 23 The ratio (E 82 / E 23 ) can be used to express the rate of decline, but E 82 / E 23 is preferably 0.75 or more, more preferably 0.80 or more. 82 / E 23 is, by its very nature, less than or equal to 1.

[0058] Here, the flexural modulus (E 23 ) and flexural modulus at 82°C (E 82 The flexural modulus (E) can be evaluated by a three-point bending test according to JIS K7171 (1994). 82 ) can be evaluated, for example, by immersing a cured resin in boiling water for two days and then performing a three-point bending test in a thermostatic chamber set to 82°C.

[0059] The epoxy resin composition of the present invention has the characteristic that the wet glass transition temperature (wet Tg) of the cured resin obtained by curing the epoxy resin composition at 180°C for 120 minutes is less likely to decrease than the dry glass transition temperature (dry Tg). When used as a structural material, such as for aircraft, the smaller the decrease in wet Tg, the better. As an indicator of this, the ratio of wet Tg to dry Tg (wet Tg / dry Tg) can be used to express the rate of decrease, and wet Tg / dry Tg is preferably 0.9 or higher, and more preferably 0.94 or higher. Note that wet Tg / dry Tg is, by nature, 1 or lower.

[0060] The dry glass transition temperature (dry Tg) and wet glass transition temperature (wet Tg) of a cured resin can be evaluated from a scatter diagram of storage modulus and temperature obtained by performing temperature-rise measurements in DMA (dynamic viscoelasticity measurement). The glass transition temperature is the temperature at the intersection of a tangent line drawn to the glass region and a tangent line drawn to the glass transition region in the scatter diagram. The wet glass transition temperature (wet Tg) can be evaluated, for example, by performing the DMA measurement using a cured resin that has been immersed in boiling water for two days.

[0061] The epoxy resin composition of the present invention has a coefficient of linear thermal expansion (α) in the range of 50°C to 100°C of the cured resin obtained by curing the epoxy resin composition at 180°C for 120 minutes. 50-100 ) is characterized by its small α 50-100 is 57 x 10 -6 / K or less, and -6 / K or less is more preferable, and -6 / K or less is more preferable. This range is preferable because it increases dimensional stability when applied as a structural material, typically for aircraft. There is no particular lower limit to the preferable range, but for example, 40 × 10 -6 / K or more, a molded product can be easily released from a molding die when producing a fiber-reinforced composite material.

[0062] Here, the coefficient of linear thermal expansion (α 50-100 ) can be evaluated by thermomechanical analysis according to ASTM E831-06.

[0063] The epoxy resin composition of the present invention may use an epoxy resin different from the components [A], [D], and [F] as component [G], as long as the effects of the present invention are not lost.

[0064] Examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenol novolac type epoxy resins, triglycidylaminophenol type epoxy resins, etc. These may be used alone or in combination of two or more types.

[0065] Commercially available bisphenol A epoxy resins include jER (registered trademark) 828 and jER (registered trademark) 825 (both manufactured by Mitsubishi Chemical Corporation).

[0066] Commercially available bisphenol F epoxy resins include "EPICLON (registered trademark)" 830 and "EPICLON (registered trademark)" 807 (both manufactured by DIC Corporation), and "jER (registered trademark)" 806 (manufactured by Mitsubishi Chemical Corporation).

[0067] Commercially available products of the phenol novolac epoxy resin include "jER (registered trademark)" 152, "jER (registered trademark)" 154, and "jER (registered trademark)" 180S (all manufactured by Mitsubishi Chemical Corporation).

[0068] Commercially available examples of the triglycidyl aminophenol type epoxy resin include "Sumiepoxy (registered trademark)" ELM100 and "Sumiepoxy (registered trademark)" ELM120 (manufactured by Sumitomo Chemical Co., Ltd.), "Araldite (registered trademark)" MY0500, "Araldite (registered trademark)" MY0510, and "Araldite (registered trademark)" MY0600 (all manufactured by Huntsman Advanced Materials), and "jER (registered trademark)" 630 (manufactured by Mitsubishi Chemical Corporation).

[0069] The epoxy resin composition of the present invention may be prepared by kneading using a machine such as a kneader, a planetary mixer, a three-roll mill, or a twin-screw extruder, or by hand using a beaker and a spatula, etc., provided that uniform kneading is possible.

[0070] The cured resin obtained by thermally curing the epoxy resin composition of the present invention is preferred because it has an excellent elastic modulus in a humid and hot environment. Furthermore, due to these characteristics, a fiber-reinforced composite material comprising the cured resin of the present invention and a reinforcing fiber substrate is preferable because it has excellent compressive strength under a humid and hot environment.

[0071] The epoxy resin composition of the present invention can be used as a fiber-reinforced composite material by combining it with a reinforcing fiber substrate. The epoxy resin composition prepared by the above method can be combined with a reinforcing fiber substrate and thermally cured to obtain a fiber-reinforced composite material in which the cured epoxy resin composition of the present invention serves as the matrix resin. The method for combining the epoxy resin composition with a reinforcing fiber substrate is not particularly limited, but examples include the RTM method, liquid composite molding method, filament winding method, hand layup method, pultrusion method, and prepreg method.

[0072] The epoxy resin composition of the present invention exhibits viscosity stability at relatively high temperatures for long periods and has excellent impregnation properties for reinforcing fiber substrates, making it particularly suitable for use in the RTM method. The RTM method involves placing a reinforcing fiber substrate or a preform in a molding die, injecting a liquid matrix resin into the die to impregnate the reinforcing fibers, and then heating to cure the matrix resin, thereby obtaining a molded fiber-reinforced composite material.

[0073] In the method for producing a fiber-reinforced composite material using the epoxy resin composition of the present invention, the epoxy resin composition of the present invention is used as a matrix resin. The temperature during injection of the epoxy resin composition is not particularly limited, but it is preferable to inject the epoxy resin composition of the present invention into a reinforcing fiber substrate placed in a mold preheated to 70°C or higher and 190°C or lower, impregnate the substrate, and then cure the composition in the mold. Preheating the mold reduces the viscosity of the epoxy resin composition, shortening the injection time and improving mass productivity. The heat-curing temperature does not need to be the same as the injection temperature; the temperature may be raised as needed to shorten the time required for heat-curing.

[0074] In the present invention, the mold used in the RTM method may be a closed mold made of a rigid material, or an open mold made of a rigid material and a flexible film (bag). In the latter case, a reinforcing fiber substrate can be placed between the open mold made of a rigid material and the flexible film. Various existing materials can be used as rigid materials, such as metals such as steel and aluminum, fiber-reinforced plastics (FRP), wood, and plaster. Materials used for the flexible film include polyamide, polyimide, polyester, fluororesin, and silicone resin.

[0075] The reinforcing fibers used in the reinforcing fiber substrate used in the fiber-reinforced composite material of the present invention are not particularly limited, and examples thereof include glass fibers, carbon fibers, aramid fibers, boron fibers, alumina fibers, and silicon carbide fibers. 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 preferred that the reinforcing fiber substrate be a carbon fiber substrate.

[0076] The fiber-reinforced composite material of the present invention has excellent mechanical properties, compressive strength under wet heat, impact resistance, and dimensional stability, and therefore can be preferably used for many structural materials, including aircraft parts such as fuselages, main wings, tail parts, moving surfaces, fairings, cowls, doors, seats, and interior materials; spacecraft parts such as motor cases and main wings; artificial satellite parts such as bodies and antennas; automobile parts such as outer panels, chassis, aerodynamic parts, and seats; railway vehicle parts such as bodies and seats; and ship parts such as hulls and seats. [Example]

[0077] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to the descriptions of these examples.

[0078] The components and evaluation methods used in the present examples are as follows: In the evaluation, unless the number of samples measured is specifically stated, the evaluation was performed with n=1.

[0079] <Materials used> (1) Component [A]: tetrafunctional glycidylamine epoxy resin "Sumiepoxy (registered trademark)" ELM-434VL (manufactured by Sumitomo Chemical Co., Ltd., epoxy equivalent: 115 g / eq).

[0080] (2) Component [B]: alkylbenzenediamine and / or methylenebisaniline (2-1) Alkylbenzenediamine "jER Cure (registered trademark)" WA (manufactured by Mitsubishi Chemical Corporation, active hydrogen equivalent: 45 g / eq), "Ethacure (registered trademark)" 300 (manufactured by Albemarle, active hydrogen equivalent: 54 g / eq).

[0081] (2-2) Methylenebisaniline "Primacure (registered trademark)" M-MIPA (manufactured by Arxada, active hydrogen equivalent: 78 g / eq).

[0082] (3) Component [C]: Silica particles "Admanano (registered trademark)" YA010C (manufactured by Admatechs Co., Ltd., average particle size: 0.01 μm, epoxy silane treated product), "Admanano (registered trademark)" YA050C (manufactured by Admatechs Co., Ltd., average particle size: 0.05 μm, epoxy silane treated product), "Admanano (registered trademark)" YA100C (manufactured by Admatechs Co., Ltd., average particle size: 0.1 μm, epoxy silane treated product), "Adma Fine (registered trademark)" SO-C1 (manufactured by Admatechs Co., Ltd., average particle size: 0.3 μm, epoxy silane treated product), "Admafine (registered trademark)" SO-C2 (manufactured by Admatechs Co., Ltd., average particle size: 0.5 μm, epoxy silane treated product).

[0083] (4) Component [D]: Aniline-type epoxy resin represented by formula (I) "TOREP (registered trademark)" A-204E (manufactured by Toray Fine Chemicals Co., Ltd., epoxy equivalent: 162 g / eq).

[0084] (5) Component [E]: A mixture of core-shell rubber particles and component [A] Kane Ace (registered trademark) MX-416 (a masterbatch containing 75% by mass of glycidylamine epoxy resin (corresponding to component [A]) and 25% by mass of butadiene-based core-shell rubber particles, manufactured by Kaneka Corporation; epoxy equivalent of glycidylamine epoxy resin: 148 g / eq).

[0085] (6) Component [F]: a solid epoxy resin selected from the group consisting of dicyclopentadiene-type epoxy resins, biphenyl-type epoxy resins, phenol aralkyl-type epoxy resins, and naphthalene-type epoxy resins. "EPICLON (registered trademark)" HP-7200H (dicyclopentadiene type epoxy resin, manufactured by DIC Corporation, epoxy equivalent: 278 g / eq).

[0086] <Method for preparing epoxy resin composition> The specified amounts of components other than component [B] and component [C] were placed in a stainless steel beaker, heated appropriately to 60-150°C, and mixed appropriately until the components were compatible. Component [C] was then added, and the mixture was mixed for 15 minutes with a planetary mixer to obtain an epoxy base liquid.

[0087] A predetermined amount of component [B] was placed in a separate container, and heated as necessary to make it compatible, thereby obtaining a curing agent liquid.

[0088] The epoxy resin composition was obtained by mixing the predetermined amounts of the base epoxy liquid and the curing agent liquid at approximately 60°C and kneading them for 3 minutes using a planetary mixer. The composition is shown in Tables 1 and 2.

[0089] <Evaluation method> The evaluation methods used in the examples are described below. In the evaluation methods, if the measurement n number is 1, the measurement n number is omitted.

[0090] (1) Flexural modulus of cured resin (23°C, 50% RH): E 23 Evaluation method The epoxy resin composition obtained according to the above <Method for preparing an epoxy resin composition> was degassed in a vacuum and then cured at 180°C for 2 hours in a mold set to a thickness of 2 mm using a 2 mm Teflon (registered trademark) spacer, yielding a 2 mm thick plate-like cured resin. Test pieces measuring 10 mm wide and 60 mm long were cut from the cured resin and subjected to three-point bending at room temperature (23°C, 50% RH) using an Instron universal testing machine (manufactured by Instron Corporation) with a span of 32 mm and a crosshead speed of 10 mm / min in accordance with JIS K7171 (1994) to measure the flexural modulus (23°C, 50% RH). Six samples were used, and the average value was used to determine the flexural modulus E 23 was adopted as the value of

[0091] (2) Flexural modulus of cured resin (humid heat 82°C): E 82 and water absorption evaluation method (1) Flexural modulus of cured resin (23°C, 50% RH): E 23 A cured resin was obtained in the same manner as in the evaluation method of 1., and test pieces 10 mm wide and 60 mm long were cut out and then immersed in boiling water for 48 hours. The removed test pieces were subjected to three-point bending in a high-temperature environment (82°C) using an Instron universal testing machine (manufactured by Instron Corporation) with a span of 32 mm and a crosshead speed of 10 mm / min in accordance with JIS K7171 (1994) to measure the flexural modulus (wet heat 82°C). The test pieces were weighed before and after immersion in boiling water for 48 hours, and the water absorption rate was calculated from the difference in mass. In this case, the number of samples (n) was 6, and the average value was used to determine the flexural modulus E 82 was adopted as the value of

[0092] (3) Evaluation method for glass transition temperature (dry Tg) of cured resin The uncured epoxy resin composition obtained according to the above-mentioned "Method for Preparing Epoxy Resin Composition" was degassed in a vacuum and then cured at 180°C for 2 hours in a mold set to a thickness of 2 mm using 2 mm Teflon (registered trademark) spacers to obtain a 2 mm-thick cured resin plate. Test pieces measuring 12.7 mm wide and 45 mm long were cut from this cured resin. Using a dynamic viscoelasticity measuring device (ARES-G2, manufactured by TA Instruments), the test pieces were mounted on a solid torsion jig with a 30 mm interchunk distance. Measurements were performed over a temperature range of 40 to 260°C at a heating rate of 5°C / min, a frequency of 1 Hz, and a strain of 0.08%. The glass transition temperature (dry Tg) was determined as the temperature at the intersection of a tangent drawn to the glassy state and a tangent drawn to the glass transition temperature region in the resulting graph of storage modulus vs. temperature.

[0093] (4) Evaluation method for glass transition temperature (wet Tg) of cured resin A cured resin was obtained using the same method as in (3) above for evaluating the glass transition temperature (dry Tg) of the cured resin, and a test piece 12.7 mm wide and 45 mm long was cut out and immersed in boiling water for 48 hours. Viscoelasticity was measured using the same method as in the above <<Evaluation method for the glass transition temperature (dry Tg) of the cured resin>> to determine the glass transition temperature (wet Tg).

[0094] (5) Evaluation method for fracture toughness of cured resin The epoxy resin composition obtained according to the above <Method for preparing an epoxy resin composition> was degassed in a vacuum and then cured for 2 hours at 180°C in a mold set to a thickness of 6 mm using a 6 mm Teflon (registered trademark) spacer, yielding a 6 mm thick plate-like cured resin. The obtained cured resin was processed into a test piece shape specified in ASTM D5045-99 and subjected to the SENB test according to ASTM D5045-99. The number of samples used was 16, and the average value was used as the K1c value.

[0095] (6) The coefficient of linear thermal expansion (α) of the cured resin in the range of 50°C to 100°C 50-100 ) Evaluation method The epoxy resin composition obtained according to the above <Method for preparing an epoxy resin composition> was degassed in a vacuum and then cured at 180°C for 2 hours in a mold set to a thickness of 6 mm using a 6 mm Teflon (registered trademark) spacer, to obtain a 6 mm thick plate-shaped cured resin. Test pieces 6 mm wide and 6 mm long were cut out from this cured resin, and thermomechanical analysis was carried out in accordance with ASTM E831-06 using a thermomechanical analyzer (Q400, manufactured by TA Instruments) to measure the coefficient of linear thermal expansion (α) in the range from 50°C to 100°C. 50-100 ) was evaluated.

[0096] Example 1 An epoxy resin composition was prepared according to the above <Method for preparing epoxy resin composition> using 70 parts by mass of Sumiepoxy (registered trademark) ELM-434VL (component [A]), 30 parts by mass of TOREP (registered trademark) A-204E (component [D]), 16.8 parts by mass of jER Cure (registered trademark) WA (component [B]), 32.6 parts by mass of Primacure (registered trademark) M-MIPA (component [B]), and 10 parts by mass of Admanano (registered trademark) YC100C.

[0097] Regarding this epoxy resin composition, the flexural modulus of the cured resin (23°C, 50% RH): E 23 (2) Flexural modulus of cured resin (humid heat 82℃): E 82 The bending properties were obtained according to the evaluation method for water absorption and E 23 is 4.20 Pa, E 82 is 3.24 GPa, and E 82 / E 23 The dry Tg was 186°C, the wet Tg was 167°C, and the wet Tg / dry Tg ratio was 0.90, demonstrating excellent heat resistance. The water absorption rate was a good 2.4%. The fracture toughness was evaluated according to the above (5) evaluation method for fracture toughness of cured resins, and was found to be 1.0 MPa m 0.5Furthermore, when the coefficient of linear thermal expansion was evaluated according to the method for evaluating the coefficient of linear thermal expansion of the cured resin (6) above, it was found that α 50-100 is 54 x 10 -6 / K and was good.

[0098] Examples 2 to 17 Epoxy resin compositions and cured resins were prepared in the same manner as in Example 1, except that the resin compositions were changed as shown in Tables 1 and 2, respectively.

[0099] The epoxy resin compositions of each Example were evaluated for wet heat and room temperature elastic modulus, wet and dry Tg, water absorption, fracture toughness, and coefficient of linear thermal expansion, and good physical properties were obtained at all levels.

[0100] (Comparative Example 1) Epoxy resin compositions and cured resins were prepared in the same manner as in Example 1, except that the resin compositions were changed as shown in Table 2.

[0101] Since the epoxy resin composition does not contain component [C], 82 The fracture toughness was low at 2.95 GPa and 0.65 MPa m 0.5 In addition, α 50-100 Also 58 x 10 -6 / K, which was quite high.

[0102] [Table 1]

[0103] [Table 2]

[0104] The units of each component in the table are parts by mass. [Industrial Applicability]

[0105] The epoxy resin composition of the present invention can provide an epoxy resin composition that has high elastic modulus and fracture toughness under wet heat conditions and a low coefficient of linear thermal expansion. Fiber-reinforced composite materials made from this epoxy resin composition also have excellent compressive properties under wet heat conditions, impact resistance, and dimensional stability, making them suitable for use in aerospace components and general industrial structural components.

Claims

1. An epoxy resin composition comprising the following components [A], [B], and [C]: [A]: tetrafunctional glycidylamine type epoxy resin [B]: alkylbenzenediamine and / or methylenebisaniline [C]: Silica particles

2. 2. The epoxy resin composition according to claim 1, wherein the silica particles have an average particle size of 1 μm or less.

3. 3. The epoxy resin composition according to claim 1, wherein the component [C] is 1 part by mass or more and 40 parts by mass or less per 100 parts by mass of the total epoxy resin.

4. 3. The epoxy resin composition according to claim 1, which contains an aniline-type epoxy resin represented by formula (I) as component [D]. 【Chemical 1】 (In formula (I), R １ and R ２ R represents at least one selected from the group consisting of aliphatic hydrocarbon groups having 1 to 4 carbon atoms. １ and R ２ When there are a plurality of, they may be the same or different. n is an integer of 0 to 4, and m is an integer of 0 to 5. X represents -O- or -S-.

5. 5. The epoxy resin composition according to claim 4, wherein the component [D] is contained in an amount of 10% by mass or more and 50% by mass or less, based on 100% by mass of the total epoxy resin.

6. 3. The epoxy resin composition according to claim 1, wherein the component [E] is 1 part by mass or more and 10 parts by mass or less of core-shell type rubber particles per 100 parts by mass of the total epoxy resin.

7. 3. The epoxy resin composition according to claim 1 or 2, comprising, as component [F], 10% by mass or more and 50% by mass or less of at least one solid epoxy resin selected from the group consisting of dicyclopentadiene-type epoxy resins, biphenyl-type epoxy resins, phenol aralkyl-type epoxy resins, and naphthalene-type epoxy resins, relative to 100% by mass of all epoxy resins.

8. 3. The epoxy resin composition according to claim 1, which contains an alkylbenzenediamine and methylenebisaniline as component [B].

9. 3. The epoxy resin composition according to claim 1, wherein the component [B] is an alkylbenzenediamine.

10. 3. The epoxy resin composition according to claim 1, further comprising dimethylthiotoluenediamine as component [B].

11. 3. The epoxy resin composition according to claim 1, which contains 4,4-methylenebis(isopropyl-6-methylaniline) as component [B].

12. 3. The epoxy resin composition according to claim 1, wherein the value (Mh / Me) obtained by dividing the total number of moles of active hydrogens (Mh) contained in component [B] by the total number of moles of active groups (Me) contained in all epoxy resins is 0.8 or more and 1.2 or less.

13. A cured resin product obtained by thermally curing the epoxy resin composition according to claim 1 or 2.

14. A fiber-reinforced composite material comprising the cured resin according to claim 13 and a reinforcing fiber substrate.

15. The fiber-reinforced composite material according to claim 14, wherein the reinforcing fiber substrate is a carbon fiber substrate.

16. A method for producing a fiber-reinforced composite material, comprising injecting the epoxy resin composition according to claim 1 or 2 into a reinforcing fiber substrate placed in a mold heated to 70°C or higher and 190°C or lower, allowing the composition to impregnate the substrate, and curing the composition in the mold.

17. The method for producing a fiber-reinforced composite material according to claim 16, wherein the reinforcing fiber substrate is a carbon fiber substrate.

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