epoxy resin composition

Abstract

To provide an epoxy resin composition which has good handleability and pot life and exhibits a relatively good flexural modulus when cured.SOLUTION: The epoxy resin composition contains an epoxy resin A represented by the following chemical formula 1, an epoxy resin B represented by a specific formula, an epoxy resin C represented by a specific formula, and a curing agent. (In the formula, R1-R4 each independently represent one selected from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group and a halogen atom; and X represents one selected from -CH2-, -O-, -S-, -CO-, -C(=O)O-, -O-C(=O)-, -NHCO-, -CONH- and -SO2-). The content of the epoxy resin A is preferably 50-90 mass% based on the total mass of epoxy resins contained in the epoxy resin composition.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin composition. In particular, the present invention relates to an epoxy resin composition for use in a fiber-reinforced composite material including a fiber-reinforced base material. [Background Art]

[0002] Fiber-reinforced resin composite materials (also referred to as fiber-reinforced composite materials or composites) are lightweight, have high strength and high rigidity, and therefore are used in a wide range of fields including sports and leisure applications such as fishing rods and golf shafts, and industrial applications such as automobiles and aircraft.

[0003] A fiber-reinforced resin composite material can be obtained, for example, by a method of molding a prepreg (intermediate base material) formed into a sheet by previously impregnating a fiber-reinforced base material with a resin. A fiber-reinforced composite material can also be obtained by a method (resin transfer molding method, RTM method) in which a fiber-reinforced base material disposed in a mold is impregnated with a liquid resin (that is, for example, an uncured curable resin or a thermoplastic resin in a molten state), followed by curing or solidification to obtain the fiber-reinforced resin composite material.

[0004] An epoxy resin composition is suitably used as a constituent component of fiber-reinforced composite materials.

[0005] Patent Document 1 describes an epoxy resin composition comprising an aliphatic epoxy resin having a specific chemical structure and an epoxy resin different from said epoxy resin. This document also describes a prepreg comprising the epoxy resin composition and a reinforcing material.

[0006] Patent Document 2 describes an epoxy resin composition formulated with a difunctional or higher functional aromatic epoxy resin and an aromatic amine compound and / or an alicyclic amine compound, the epoxy resin composition having specific physical properties. This document describes the prepreg method, RTM method and the like as methods for producing fiber-reinforced composite materials.

[0007] Patent Document 3 describes a liquid resin composition for compression molding containing an aliphatic epoxy compound, an epoxy compound having an aromatic ring in its molecule, a nitrogen-containing heterocyclic compound, and an inorganic filler. This document claims that it can provide a liquid resin composition for compression molding that can suppress the occurrence of warping in semiconductor wafers, and an electronic component device using the same.

[0008] Patent Document 4 describes a crosslinking agent composition for resins, comprising an epoxy resin having a chain-like polyhydric alcohol skeleton with a specific chemical structure and an epoxy resin having a glycerin skeleton or polyglycerin skeleton with a specific chemical structure.

[0009] Patent Document 5 describes a curable resin composition comprising an epoxy resin of a specific structure and / or an epoxy (meth)acrylate of a specific structure. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2006-83216 [Patent Document 2] International Publication No. 00 / 53654 [Patent Document 3] International Publication No. 2018 / 221682 [Patent Document 4] Japanese Patent Publication No. 2017-66343 [Patent Document 5] Japanese Patent Publication No. 2023-19448 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] When epoxy resin compositions are used in fiber-reinforced composite materials, good handling properties and pot life are required, as well as high physical properties (particularly high mechanical properties) for the molded products obtained by curing the epoxy resin composition. Furthermore, it is preferable that the epoxy resin composition used in fiber-reinforced composite materials has a relatively high glass transition temperature.

[0012] Conventional epoxy resin compositions have not been easy to satisfy these requirements.

[0013] An object of the present invention is to provide an epoxy resin composition that has good handleability and pot life, and gives a cured molded article excellent in mechanical properties. Furthermore, an object of the present invention is to provide an epoxy resin composition that has good handleability and pot life, exhibits a relatively high glass transition temperature, and gives a cured molded article excellent in mechanical properties.

Means for Solving the Problems

[0014] The object of the present invention can be solved by the following aspects of the present invention. <Aspect 1> Epoxy resin A represented by the following Chemical Formula 1, Epoxy resin B represented by the following Chemical Formula 2, Epoxy resin C represented by the following Chemical Formula 3, and a curing agent An epoxy resin composition comprising:

Chemical Formula

Chemical Formula

Chemical Formula

Chemical Formula

Chemical Formula

[0015] According to the present invention, it is possible to provide an epoxy resin composition that has good handling properties and pot life, as well as excellent mechanical properties of the molded product obtained after curing.

[0016] Furthermore, according to the present invention, it is possible to provide an epoxy resin composition that has good handling properties and pot life, exhibits a relatively high glass transition temperature, and has excellent mechanical properties for the molded product obtained after curing. [Modes for carrying out the invention]

[0017] <<Epoxy resin composition>> The epoxy resin composition according to the present invention is Epoxy resin A, represented by the following chemical formula 1, Epoxy resin B, represented by the following chemical formula 2, The epoxy resin C represented by the following chemical formula 3, and hardening agent It contains.

[0018] As a result of their investigations, the inventors of this invention have found that an epoxy resin composition containing three types of epoxy resins with the following specific chemical structures can be used to obtain the desired excellent properties. More specifically, the epoxy resin composition according to the present invention has a relatively low viscosity at 100°C, making it easy to handle, and a relatively high curing start temperature, resulting in excellent pot life. Furthermore, the epoxy resin composition according to the present invention exhibits excellent mechanical properties in the molded product obtained after curing, and in particular, shows a relatively good flexural modulus. Moreover, the epoxy resin composition according to the present invention can exhibit a relatively high glass transition temperature.

[0019] Although there is no intention to limit the theory, in this invention, by using three specific epoxy resin compositions that differ from each other in terms of the number of epoxy groups in the molecule, the presence or absence of aromatic rings, the length of the carbon chain, and the number of oxygen atoms, it is believed that good physical properties in terms of viscosity, curing start temperature, and even glass transition temperature of the epoxy resin composition can be obtained, and a relatively high flexural modulus can be obtained for the molded product obtained after curing.

[0020] <Epoxy resin A> Epoxy resin A is represented by the following chemical formula 1. [ka] (In Formula 1, R1 to R4 each independently represent one selected from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and a halogen atom, and X represents one selected from -CH2-, -O-, -S-, -CO-, -C(=O)O-, -OC(=O)-, -NHCO-, -CONH-, and -SO2-.)

[0021] The epoxy resin composition relating to this disclosure may contain multiple types of compounds corresponding to the above formula 1 as epoxy resin A.

[0022] In Formula 1 above, R1 to R4 preferably each independently represent one selected from the group consisting of a hydrogen atom and an aliphatic hydrocarbon group, and particularly preferably all are hydrogen atoms.

[0023] If at least one of R1 to R4 is an aliphatic hydrocarbon group, this aliphatic hydrocarbon group may be an alkyl group having 1 to 6 carbon atoms. If at least one of R1 to R4 is an aliphatic hydrocarbon group, these are preferably alkyl groups having 1 to 4 carbon atoms, and particularly preferably methyl or ethyl groups. If at least one of R1 to R4 is an alicyclic hydrocarbon group, this alicyclic hydrocarbon group may have 3 to 12 carbon atoms, and particularly 6 to 10 carbon atoms.

[0024] In the above formula 1, X is preferably -CH2- or -O-.

[0025] The content of epoxy resin A in the epoxy resin composition may be 35 to 90% by mass, based on the total mass of epoxy resin contained in the epoxy resin composition.

[0026] Epoxy resin A is preferably 40-90% by mass or 40-85% by mass, 50-90% by mass or 50-85% by mass, more than 50% by mass and 85% by mass or less, or even more than 60-82% by mass, based on the total mass of the epoxy resin contained in the epoxy resin composition.

[0027] A higher glass transition temperature can be obtained if epoxy resin A accounts for 40% by mass or more, or more than 50% by mass, and especially more than 60% by mass, based on the total mass of epoxy resin contained in the epoxy resin composition.

[0028] When epoxy resin A accounts for 85% by mass or less, and particularly 82% by mass or less, of the total mass of epoxy resin contained in the epoxy resin composition, the curing efficiency when curing the epoxy resin composition can be improved by preventing the curing start temperature from becoming excessively high.

[0029] In a particularly preferred embodiment of the present disclosure, epoxy resin A is one or more combinations selected from the group consisting of tetraglycidyl-4,4'-diaminodiphenyl ether, tetraglycidyl-4,4'-diaminodiphenylmethane, tetraglycidyl-3,4'-diaminodiphenyl ether, and tetraglycidyl-3,3'-diaminodiphenylmethane.

[0030] Specific examples of epoxy resin A include compounds represented by the following formulas 1-1 or 1-2.

[0031] [ka]

[0032] In one preferred embodiment, the epoxy resin composition contains both the compound represented by formula 1-1 and the compound represented by formula 1-2 as epoxy resin A.

[0033] When the epoxy resin composition contains both the compound represented by formula 1-1 and the compound represented by formula 1-2, the content of the compound represented by formula 1-1 may be 60 to 90% by mass, and preferably 65 to 80% by mass, based on the total mass of epoxy resin A.

[0034] Furthermore, when the epoxy resin composition contains both the compound represented by formula 1-1 and the compound represented by formula 1-2, the content of the compound represented by formula 1-2 may be 10 to 40% by mass, and preferably 20 to 35% by mass, based on the total mass of epoxy resin A.

[0035] <Epoxy resin B> Epoxy resin B is represented by the following chemical formula 2. [ka] (In formula 2, R5 and R6 are each independently an aliphatic hydrocarbon group having 4 to 12 carbon atoms.)

[0036] R5 and R6 are each preferably an aliphatic hydrocarbon group having 5 to 10 carbon atoms, and more preferably an aliphatic hydrocarbon group having 6 to 8 carbon atoms. R5 may be an alkylene group, and R6 may be an alkyl group.

[0037] A specific example of a preferred epoxy resin B is the epoxy resin represented by the following chemical formula 2-1. [ka]

[0038] The content of epoxy resin B in the epoxy resin composition is preferably 2 to 35% by mass, more preferably 6 to 28% by mass, and particularly preferably 8 to 22% by mass or even more preferably 12 to 22% by mass, based on the total mass of epoxy resin contained in the epoxy resin composition.

[0039] <Epoxy resin C> Epoxy resin C is represented by the following chemical formula 3. [ka] (In equation 3, m is an integer from 0 to 20, R7 to R) 10 Each of these is independently a hydrogen atom or a glycidyl group represented by the following chemical formula 4, and R7~R 10 Of these, at least two are glycidyl groups represented by the following chemical formula 4. [ka]

[0040] m is preferably an integer of 1 to 10, more preferably an integer of 2 to 6, or even 2 to 4, and particularly preferably m=3.

[0041] Particularly preferably, 4 of R7 to R 10 are glycidyl groups represented by the above formula 4. That is, it is particularly preferable that the compound represented by formula 3 is a compound containing four glycidyl groups.

[0042] Epoxy resin C is particularly preferably an epoxy resin represented by the following chemical formula 3-1. Chemical formula

[0043] The content of epoxy resin C in the epoxy resin composition is preferably 2 to 35% by mass, more preferably 6 to 28% by mass, based on the total mass of epoxy resins contained in the epoxy resin composition, and particularly preferably 8 to 18% by mass, or even 10 to 18% by mass.

[0044] <Regarding Component B and Component C>

[0045] The total amount of epoxy resins B and C may be 5 to 65% by mass based on the total mass of epoxy resins contained in the epoxy resin composition.

[0046] The total amount of epoxy resins B and C is preferably 10 to 50% by mass, more preferably 15 to 45% by mass, or even 16 to 45% by mass, based on the total mass of epoxy resins contained in the epoxy resin composition, and particularly preferably 18 to 42% by mass, or even 20 to 40% by mass. Since both epoxy resin B and epoxy resin C can be provided as biomass-derived components, a relatively high content of epoxy resins B and C is preferable from the viewpoint of obtaining a composition with further excellent environmental compatibility.

[0047] The ratio Mb / Mc of the content of epoxy resin B in the epoxy resin composition to the content of epoxy resin C in the epoxy resin composition (Mb / Mc) may be between 0.2 and 5.0.

[0048] This ratio Mb / Mc is preferably 0.4 to 4.5, more preferably 0.6 to 4.0, and particularly preferably 0.8 to 3.5.

[0049] <Biomass-derived ingredients> In one embodiment of the present disclosure, at least one of epoxy resin B and epoxy resin C is a biomass-derived epoxy resin.

[0050] Both epoxy resin B and epoxy resin C can be provided as biomass-derived components. Specifically, for example, component B can be produced from cashew nut shell oil, and component C can be produced from palm oil. Examples of commercially available biomass-derived products include Cardolite® NC-514S (manufactured by Cardolite Corporation) for component B, and Denacol EX-512 (manufactured by Nagase ChemteX Corporation) for component C.

[0051] According to the present invention, compared to the case in which either epoxy resin B or epoxy resin C is contained alone, relatively good properties can be obtained by using epoxy resin B and epoxy resin C in combination for the same amount. Therefore, according to the present invention, it is possible to increase the proportion of biomass-derived components in the epoxy resin composition while maintaining the good performance of the epoxy resin composition. By increasing the amount of biomass-derived components contained in the epoxy resin composition, it is possible to provide an epoxy resin composition and products using the same that are more environmentally friendly.

[0052] <Hardening agent> The epoxy resin composition according to this disclosure includes a curing agent. Any known curing agent can be used as the curing agent. In particular, the use of an amine-based curing agent is preferred from the viewpoint of the mechanical properties of the cured product.

[0053] Amine-based curing agents include ethylenediamine, 4,4'-diamino-3,3'-diisopropyl-5,5'-dimethyldiphenylmethane, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripylenetetramine, tetraethylenepentamine, hexamethylenediamine, iminobispropylamine, bis(hexamethylene)triamine, 1,3,6-trisaminomethylhexane, trimethylhexamethylenediamine, polyetherdiamine, diethylaminopropylamine, polyethyleneimine dimer acid ester, dicyandiamide, tetramethylguanidine, adipic acid hydrazide, mensendiamine, 1,4-cyclohexanediamine, isophoronediamine, bis(aminomethyl)norbornane, and bis(4-aminocyclohexyl)methane. Examples include amine compounds having a primary amine in the molecule, such as N-aminoethylpiperazine, diaminodicyclohexylmethane, bisaminomethylcyclohexane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro(5,5)undecane, norbornenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, and diaminodiethyldiphenylmethane; linear polyamine compounds such as 1,2-propanediamine and 1,3-butanediamine; and amine compounds having a secondary amine in the molecule, such as N-methylpiperazine, morpholine, piperidine, N-methylaniline, N-ethylaniline, N-ethyltoluidine, diphenylamine, hydroxyphenylglycine, and N-methylaminophenol sulfate. These may be used individually or in combination of two or more types.

[0054] The curing agent is preferably 4,4'-diamino-3,3'-diisopropyl-5,5'-dimethyldiphenylmethane (M-MIPA).

[0055] The amount of curing agent may be 40 to 80 parts by weight, or even more precisely, 45 to 70 parts by weight, per 100 parts by weight of the total epoxy resin in the epoxy resin composition.

[0056] The total amount of curing agent contained in the epoxy resin composition that can be used in the present invention is an amount suitable for curing all the epoxy resins blended in the composition, and can be appropriately adjusted depending on the type of epoxy resin and curing agent used.

[0057] Specifically, for example, it is preferable that the ratio of the number of epoxy groups derived from the epoxy resin in the composition to the number of active hydrogens derived from the curing agent be 0.7 to 1.3.

[0058] <Other ingredients> The epoxy resin composition according to this disclosure may contain other components in addition to the epoxy resin and curing agent described above, such as curing accelerators, other epoxy resins, colorants, fillers, and various additives. Furthermore, in order to improve the impact resistance of the matrix resin, thermoplastic resin components and resin particles (e.g., core-shell rubber particles) may be included as other components. Preferably, the total amount of these other components is 20% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less, based on the total mass of the epoxy resin composition.

[0059] (Curing accelerator) The epoxy resin composition may also contain an accelerator (curing accelerator).

[0060] Examples of curing accelerators include urea compounds, particularly aromatic urea compounds (aromatic urea compounds). Specific examples include 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 1,1'-(4-methyl-1,3-phenylene)bis(3,3-dimethylurea), N-phenyl-N',N'-dimethylurea, N-(4-chlorophenyl)-N',N'-dimethylurea, N-(3,4-dichlorophenyl)-N',N'-dimethylurea, N-(3-chloro-4-methylphenyl)-N',N'-dimethylurea, N-(3-chloro-4-ethylphenyl)-N',N'-dimethylurea, N-(3-chloro-4-methoxyphenyl)-N',N'-dimethylurea, N-(4-methyl-3-nitrophenyl)-N',N'-dimethylurea, 2,4-bis(N',N'-dimethylureido)toluene, methylene-bis(p-N',N'-dimethylureidophenyl), and others. Of these, 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 1,1'-(4-methyl-1,3-phenylene)bis(3,3-dimethylurea) are preferred. These may be used individually or in combination of two or more.

[0061] If a curing accelerator is included, its content may be 1 to 10 parts by weight, or even more precisely, 2 to 6 parts by weight, per 100 parts by weight of the total epoxy resin in the epoxy resin composition.

[0062] (Core-shell rubber particles) The epoxy resin composition relating to this disclosure may contain core-shell rubber particles (CSR) to impart further toughness.

[0063] Examples of such core-shell rubber particles include those having a polybutadiene core and a tetraglycidyl-4,4'-diaminodiphenylmethane shell. A specific commercially available product is the Kaneka® MX series from Kaneka Corporation.

[0064] If core-shell rubber particles are included, their content may be 1 to 15 parts by mass, 1 to 10 parts by mass, or even 2 to 6 parts by mass, per 100 parts by mass of the total epoxy resin in the epoxy resin composition.

[0065] (Other epoxy resins) The epoxy resin composition relating to this disclosure may contain other epoxy resins other than epoxy resins A to C described above, to the extent that the effects of the present invention are not hindered. Preferably, the other epoxy resin is contained in an amount of 10% by mass or less, 5% by mass or less, or 3% by mass or less, based on the total mass of the epoxy resin composition. Examples of other epoxy resins include DGEBA and GOT. [ka]

[0066] If other epoxy resins besides epoxy resins A to C are included, their content may be 0.5 to 8 parts by weight, or even 1 to 4 parts by weight, per 100 parts by weight of the total epoxy resins in the epoxy resin composition.

[0067] <Composition> In one embodiment of the present disclosure, the epoxy resin composition comprises the following components in the following amounts relative to 100 parts by weight of the total epoxy resin in the epoxy resin composition: 35 to 90 parts by mass of epoxy resin A 2 to 35 parts by mass of epoxy resin B 2 to 35 parts by mass of epoxy resin C 0 to 10 parts by mass of other epoxy resin 0 to 10 parts by mass of core-shell rubber particles 40 to 80 parts by mass of curing agent.

[0068] In one preferred embodiment of the present disclosure, the epoxy resin composition comprises the following components in the following amounts relative to the total mass of the epoxy resin composition: Epoxy resin A in amounts of more than 50 parts by mass and less than or equal to 82 parts by mass 6 to 28 parts by mass of epoxy resin B 6 to 28 parts by mass of epoxy resin C 0 to 6 parts by mass of other epoxy resin 0 to 5 parts by mass of core-shell rubber particles 45 to 80 parts by mass of curing agent.

[0069] In one preferred embodiment of the present disclosure, the epoxy resin composition comprises the following components in the following amounts relative to the total mass of the epoxy resin composition: 60 to 82 parts by mass of epoxy resin A 8 to 22 parts by mass of epoxy resin B 8 to 18 parts by mass of epoxy resin C 0 to 3 parts by mass of other epoxy resin 0 to 6 parts by mass of core-shell rubber particles 45 to 70 parts by mass of curing agent.

[0070] <Cured resin> This disclosure includes resin cured products obtained by curing the epoxy resin composition relating to this disclosure.

[0071] The method for curing an epoxy resin composition to produce a cured resin product is not particularly limited. For example, a cured resin product can be produced by heat-treating the epoxy resin composition according to this disclosure at 130 to 180°C for 0.5 to 2 hours.

[0072] <Fiber-reinforced composite materials> This disclosure also includes fiber-reinforced composite materials. The fiber-reinforced composite material includes a resin cured product obtained by curing an epoxy resin composition according to this disclosure and a fiber-reinforced substrate.

[0073] The fiber-reinforced composite material according to this disclosure can be obtained, for example, by impregnating a fiber-reinforced substrate with a liquid resin (i.e., an uncured epoxy resin composition) and curing or solidifying it.

[0074] There are no particular restrictions on the method for producing fiber-reinforced composite materials. A prepreg may be formed by pre-impregnating a fiber-reinforced substrate with a matrix resin, or the fiber-reinforced substrate and matrix resin may be composited simultaneously with molding using methods such as resin transfer molding (RTM) or resin film infusion molding (RFI). Specific manufacturing methods for obtaining fiber-reinforced composite materials will be described later.

[0075] <Fiber-reinforced substrate> The fiber-reinforced substrate contains reinforcing fibers. Preferably, the fiber-reinforced substrate is a carbon fiber-reinforced substrate.

[0076] (Reinforced fiber sheet) The fiber-reinforced substrate may have one or more reinforcing fiber sheets containing reinforcing fibers.

[0077] The reinforced fiber sheet may be a woven fabric in which reinforced fibers are used as warp and weft threads in a plain weave or satin weave. In such a fabric, for example, the reinforced fibers as warp threads and the reinforced fibers as weft threads extend perpendicularly to each other.

[0078] In contrast, a unidirectional (UD) reinforced fiber sheet, in which the reinforcing fibers are aligned in one direction, can be used. An example of such a unidirectional reinforced fiber sheet is a UD-woven fabric. A unidirectional fabric is a fabric composed of reinforcing fibers aligned in one direction as warp threads and auxiliary threads as weft threads, and is a so-called bamboo blind fabric.

[0079] Furthermore, non-crimp fabric can also be used as the fiber-reinforced base material. In non-crimp fabric, multiple reinforced fiber sheets, each made of reinforced fibers aligned in one direction, are laminated together, and these laminated reinforced fiber sheets are sewn together with stitching thread, which acts as an auxiliary thread. In other words, in non-crimp fabric, the laminate of reinforced fiber sheets, each made of reinforced fibers aligned in one direction, is integrated by being sewn together with auxiliary thread (particularly called stitching thread) that penetrates the laminate in the thickness direction.

[0080] (Reinforced fiber) Examples of reinforcing fibers that constitute the fiber-reinforced substrate include carbon fibers, glass fibers, aramid fibers, boron fibers, and metal fibers. The reinforcing fibers are preferably carbon fibers.

[0081] The average length of the reinforcing fibers is not particularly limited, but may be, for example, 5 cm to 100 m.

[0082] The fiber-reinforced substrate relating to this disclosure preferably has a density of 100 to 2000 g / m². 2 Comfortable 150~1500g / m 2 It has a basis weight of [value]. Furthermore, the thickness of the fiber-reinforced substrate according to this disclosure can be appropriately selected depending on the application of the molded product, but may be 0.1 to 2 mm or 0.5 to 1.5 mm.

[0083] (Support thread) In a fiber-reinforced substrate, auxiliary threads play a role in maintaining the integrity of the reinforced fiber sheets and / or the fiber-reinforced substrate by connecting the reinforcing fibers to each other and / or the reinforcing fiber sheets to each other. The auxiliary threads may include polyolefin fibers, polyamide resins, polyester resins, cellulose fibers, polyethersulfone (PES) resins, or polyetherimide (PEI) resins, or mixtures thereof. Alternatively, the auxiliary threads may consist of at least one of these.

[0084] (Resin material layer) The fiber-reinforced substrate according to this disclosure may include one or more reinforcing fiber sheets and one or more resin material layers. The resin material layers may be sheets containing thermoplastic resin fibers, and in particular nonwoven fabrics containing thermoplastic resin fibers. In one embodiment according to this disclosure, the resin material layer is a nonwoven fabric manufactured by a melt-blown method. By using the melt-blown method, it is possible to manufacture a nonwoven fabric containing thermoplastic resin fibers with a finer fiber diameter compared to when using the spunbond method.

[0085] The resin material layer can be laminated, for example, together with a reinforcing fiber sheet to form a laminate. In such a laminate, the resin material layer may be positioned between the reinforcing fiber sheets. Preferably, the resin material layer is adjacent to the reinforcing fiber sheet, and in particular, positioned on the surface of the reinforcing fiber sheet. The presence of a resin material layer in the fiber-reinforced substrate can improve the impact resistance of the fiber-reinforced resin composite material produced from the fiber-reinforced substrate.

[0086] <Method for manufacturing fiber-reinforced composite materials> This disclosure also includes a method for producing fiber-reinforced composite materials, the method being To form an intermediate composite comprising a fiber-reinforced substrate and an epoxy resin composition according to the present disclosure, The intermediate composite is hardened to form a fiber-reinforced composite material. Includes.

[0087] The "intermediate composite" may be, for example, a fiber-reinforced substrate impregnated with an epoxy resin composition. Details of this manufacturing method are described below with reference to exemplary embodiments.

[0088] One exemplary embodiment of a method for producing a fiber-reinforced composite material relating to this disclosure is: The epoxy resin composition relating to this disclosure is impregnated into a fiber-reinforced substrate placed in a mold, and A fiber-reinforced substrate impregnated with the epoxy resin composition according to this disclosure is cured under heat to form a fiber-reinforced composite material. Includes.

[0089] When impregnating with an epoxy resin composition, for example, a fiber-reinforced substrate placed in a mold is impregnated with a liquid epoxy resin composition before curing, which is used as the matrix resin.

[0090] The mold may be a closed mold made of a rigid material, or it may be an open mold made of a rigid material and a flexible film (bag). In the latter case, the fiber-reinforced substrate can be placed between the open mold made of the 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 gypsum. Materials used for the flexible film include polyamide, polyimide, polyester, fluororesin, and silicone resin.

[0091] When using a closed mold made of rigid material, the mold is typically clamped under pressure, and the resin composition is injected under pressure. In this case, it is also possible to provide a suction port in addition to the injection port and connect it to a vacuum pump for suction. By using suction, it is possible to inject the resin composition using only atmospheric pressure without the need for special pressurizing means. This method is suitable because it allows for the manufacture of large components by providing multiple suction ports.

[0092] When using an open mold of a rigid material and a flexible film, the resin composition may be injected using only atmospheric pressure by suction, without the use of any special pressurizing means. To achieve good impregnation with injection using only atmospheric pressure, it is effective to use a resin diffusion medium. Furthermore, it is preferable to apply a gel coat to the surface of the rigid material prior to the installation of the fiber-reinforced substrate.

[0093] The impregnation pressure when impregnating a fiber-reinforced substrate with an epoxy resin composition can be appropriately determined considering the viscosity and flow of the resin. The specific impregnation pressure is preferably 0.001 to 10 MPa, and more preferably 0.01 to 1 MPa. The viscosity of the epoxy resin used in manufacturing the fiber-reinforced composite material is preferably less than 5000 mPa·s at 100°C, and more preferably 1 to 1000 mPa·s.

[0094] In the above manufacturing method, the viscosity of the resin composition is preferably 0.01 to 1 Pa·s at the injection temperature. It is preferable to pre-treat the resin to be injected by heating or other methods to adjust the viscosity at the time of injection to the above range.

[0095] In the manufacturing method according to this disclosure, a fiber-reinforced substrate impregnated with an epoxy resin composition is cured under heat. The mold temperature during heat curing is usually selected to be higher than the mold temperature during injection of the thermosetting resin. The mold temperature during heat curing is preferably 80 to 200°C. The heat curing time is preferably 1 minute to 20 hours. After heat curing is complete, the fiber-reinforced composite material is removed by demolding. Subsequently, the obtained fiber-reinforced composite material may be heated at a higher temperature for post-curing. The post-curing temperature is preferably 150 to 200°C, and the time is preferably 1 minute to 4 hours.

[0096] The amount of epoxy resin composition may be 20 to 60 parts by mass per 100 parts by mass of fiber-reinforced substrate.

[0097] <Preform material> When molding fiber-reinforced composite materials using fiber-reinforced substrates, the fiber-reinforced substrates can be used as they are. However, from the viewpoint of handling and workability, it is preferable to use a preform material that has been pre-molded by stacking fiber-reinforced substrates.

[0098] Preform material can be manufactured by a method that includes a step of heating a composite (particularly a composite composed of these) containing a fiber-reinforced substrate and a binder resin under pressure. For example, preform material is manufactured by stacking fiber-reinforced substrates on one side of a preform mold to a desired thickness, scattering binder resin powder or laminating resin sheets as needed, and then pre-forming by heating under pressure using a press with a heating plate or the like. The resin melts upon heating, and the fiber-reinforced substrates are molded to conform to the mold, resulting in a preform material that maintains the shape of the mold.

[0099] The resin material used as the binder resin is not particularly limited, and thermosetting resins such as epoxy resins and vinyl ester resins, thermoplastic resins such as polyamides and polyethersulfones, and mixtures thereof can be used as appropriate. These resins may be used by scattering them as powder, or they may be formed into sheets or nonwoven fabrics and laminated onto the fiber-reinforced substrate of the present invention. Alternatively, they may be pre-attached to each yarn constituting the fiber-reinforced substrate of the present invention.

[0100] The amount of binder resin constituting the preform material is preferably 1 to 20 parts by mass, and more preferably 5 to 10 parts by mass, per 100 parts by mass of the fiber-reinforced base material of the present invention. The thickness of the preform material varies depending on the intended use, but is preferably 1 to 40 mm.

[0101] <Application> The applications of the epoxy resin composition and the fiber-reinforced resin composite material produced from the epoxy resin composition are not particularly limited, but can be used, for example, as structural materials for aircraft, automobiles, railway vehicles, and ships. [Examples]

[0102] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The components and measurement methods used in the examples and comparative examples are listed below.

[0103] <<Ingredients>> <Epoxy resin> Epoxy resin A • Tetraglycidyl-3,4'-diaminodiphenyl ether (synthesized by the method in Synthesis Example 1, represented by the chemical formula 1-1 below. Hereafter abbreviated as "3,4'-TGDDE"). [ka] • Tetraglycidyl-4,4'-diaminodiphenylmethane (Araldite MY721, manufactured by Huntsman. The compound represented by chemical formulas 1-2 below. Hereafter abbreviated as "TGDDM") [ka]

[0104] Epoxy resin B • Epoxy resin having the structure shown in chemical formula 2-1 below (Cardwright NC-514S) [ka]

[0105] Epoxy resin C • Polyglycerol polyglycidyl ether having the chemical structure shown in chemical formula 3-1 below (EX-512, manufactured by Nagase ChemteX Corporation) [ka]

[0106] Other epoxy resins • Bisphenol A-diglycidyl ether (manufactured by Mitsubishi Chemical Corporation, jER825; hereinafter abbreviated as "DGEBA") • N,N-Diglycidyl-o-Toluidine (GOT, manufactured by Nippon Kayaku Co., Ltd., hereinafter abbreviated as "GOT") • Sorbitol polyglycidyl ether represented by the following chemical formula 5 (EX-612, manufactured by Nagase ChemteX Corporation) [ka]

[0107] (Amine-based curing agent) • 4,4'-diamino-3,3'-diisopropyl-5,5'-dimethyldiphenylmethane (Lonzacure M-MIPA, manufactured by Lonza Corporation; hereinafter abbreviated as "M-MIPA") [ka]

[0108] (Additives) • MX-416 (MX-416 manufactured by Kaneka Corporation, a masterbatch in which particulate butadiene rubber component (CSR) is dispersed in a glycidylamine-type tetrafunctional epoxy resin at a concentration of 25% by mass) (The glycidylamine-type tetrafunctional epoxy resin in the product is tetraglycidyl-4,4'-diaminodiphenylmethane, which corresponds to epoxy resin A of the present invention.)

[0109] <Synthesis Example 1> Synthesis of 3,4'-TGDDE 1110.2 g (12.0 mol) of epichlorohydrin was placed in a four-necked flask equipped with a thermometer, dropping funnel, condenser, and stirrer. The temperature was raised to 70°C while purging with nitrogen, and 200.2 g (1.0 mol) of 3,4'-diaminodiphenyl ether dissolved in 1000 g of ethanol was added dropwise over 4 hours. The mixture was stirred for a further 6 hours to complete the addition reaction, yielding N,N,N',N'-tetrakis(2-hydroxy-3-chloropropyl)-3,4'-diaminodiphenyl ether. Subsequently, the temperature in the flask was lowered to 25°C, and 500.0 g (6.0 mol) of 48% NaOH aqueous solution was added dropwise over 2 hours, followed by stirring for another hour. After the cyclization reaction was complete, the ethanol was removed by distillation, and the mixture was extracted with 400 g of toluene and washed twice with 5% saline solution. When toluene and epichlorohydrin were removed from the organic layer under reduced pressure, 361.7 g (85.2% yield) of a brownish viscous liquid was obtained. The purity of the main product, 3,4'-TGDDE, was 84% ​​(HPLC area %).

[0110] <<Evaluation Method>> (1) Physical properties of the resin composition (1-1) Preparation of epoxy resin composition The epoxy resin composition was prepared by mixing the epoxy resin and additives, heated to 80°C, in the proportions shown in Tables 1 and 2 below, using a stirrer, and then adding the curing agent and mixing for 30 minutes. In the compositions shown in Tables 1 and 2, the glycidyl groups of the epoxy resin and the amino groups of the curing agent are equivalent in weight.

[0111] (1-2)100℃ viscosity The viscosity of the epoxy resin composition obtained in (1-1) above was measured at 100°C using a Type B viscometer TVB-15M manufactured by Toki Sangyo Co., Ltd.

[0112] (1-3) Curing start temperature 2.5 to 3.5 mg of the epoxy resin composition obtained in (1-1) above was weighed and DSC measurement was performed. In the resulting chart, the intersection of the baseline and the tangent at the inflection point on the low-temperature side was defined as the curing start temperature. The DSC measurement was performed under the following conditions. ·Measurement temperature range: 30~350℃ • Heating rate: 10℃ / min

[0113] (2) Physical properties of cured resin products (2-1) Preparation of resin cured products The epoxy resin composition prepared in (1-1) above was degassed in a vacuum and then injected into a silicone resin mold set to a thickness of 4 mm using a 4 mm thick silicone resin spacer. It was cured at a temperature of 180°C for 2 hours to obtain a 4 mm thick cured resin product.

[0114] (2-2) Glass transition temperature after water absorption (DMA-wet-Tg) The glass transition temperature was measured according to the SACMA 18R-94 method. The cured resin obtained in (2-1) above was cut and polished to prepare test specimens with dimensions of 50 mm × 6 mm × 2 mm. The prepared resin test specimens were subjected to water absorption treatment at 121 °C for 24 hours using a pressure cooker (ESPEC, HASTEST PC-422R8). Using a Rheogel-E400 dynamic viscoelasticity analyzer manufactured by UBM, the storage modulus E' of the water-treated resin test specimens was measured from 50 °C to the rubber elastic region with a measurement frequency of 1 Hz, a heating rate of 5 °C / min, and a strain of 0.0167%, with a distance of 30 mm between the chucks. logE' was plotted against temperature, and the temperature obtained from the intersection of the approximate straight line of the flat region of logE' and the approximate straight line of the region where E' transitions was recorded as the glass transition temperature (wet-Tg).

[0115] (2-3) Flexural modulus of resin The test was conducted in accordance with the JIS K7171 method. The resin test specimen was prepared with dimensions of 80 mm × 10 mm × h4 mm. The bending test was performed with a support distance L of 16 × h (thickness) and a test speed of 2 m / min, and the bending modulus was measured.

[0116] <<Examples 1-9>> In Examples 1 to 9, epoxy resin compositions were obtained by mixing the components listed in Table 1 using a stirrer. The physical properties of the obtained epoxy resin compositions and the cured resin products are shown in Table 1. The amount of MX-416 added was adjusted so that the CSR was the mass percentage shown in Table 1 relative to the total weight of the resin composition.

[0117] [Table 1]

[0118] <<Comparative Examples 1-9>> In Comparative Examples 1 to 9, epoxy resin compositions were obtained by mixing the components listed in Table 2 using a stirrer. The physical properties of the obtained epoxy resin compositions and the cured resin products are shown in Table 2. The amount of MX-416 added was adjusted so that the CSR was the mass percentage shown in Table 2 relative to the total weight of the resin composition.

[0119] [Table 2]

[0120] As can be seen in Table 1, the epoxy resin compositions of Examples 1 to 9, which contained epoxy resins A to C, all showed good results for each physical property. Specifically, the composition properties of viscosity at 100°C and curing initiation temperature were both good, as were the cured product properties of glass transition temperature after water absorption (wet-Tg) and flexural modulus.

[0121] On the other hand, as can be seen in Table 2, Comparative Examples 1 to 9, which did not contain at least one of epoxy resins A to C, showed relatively inferior physical properties in some cases.

[0122] Specifically, Comparative Examples 1 and 5 contained epoxy resin B but not epoxy resin C, resulting in relatively inferior flexural modulus of the cured product. Furthermore, comparing Comparative Example 1 (component B only) with Examples 1-2 (component B + component C), Comparative Example 1 had a relatively low glass transition temperature. The same was true when comparing Comparative Example 5 (component B only) with Examples 3-4 (component B + component C).

[0123] Comparative Examples 2, 6, and 7 contained epoxy resin C but lacked epoxy resin B, resulting in excessively high viscosity. Excessive viscosity makes epoxy resin compositions difficult to handle.

[0124] Comparative Example 3 is an example in which the compound represented by chemical formula 5 was used instead of the compound represented by chemical formula 3-1 as the epoxy resin C. The compound represented by chemical formula 5 does not meet the requirements of chemical formula 3 for epoxy resin C. As can be seen in Table 2, Comparative Example 3 showed an excessively high viscosity.

[0125] In Comparative Example 4, when GOT was used instead of epoxy resin A, the wet-Tg value decreased significantly.

[0126] Comparative Examples 8 and 9, which did not use epoxy resins B and C, exhibited excessively high viscosity and excessively high curing initiation temperatures. An excessively high curing initiation temperature may result in insufficient curing efficiency when curing the epoxy resin composition.

[0127] In particular, the above results show that by using epoxy resins B and C in combination, superior physical properties can be obtained compared to using epoxy resin B or epoxy resin C alone. Epoxy resins B and C can be derived from biomass, and in fact, NC514S and Ex-512, used as epoxy resins B and C in the examples, are both biomass-derived epoxy resins. Therefore, by using epoxy resins B and C in combination according to the present invention, a relatively large number of biomass-derived components can be used in the epoxy resin composition while ensuring the desired superior physical properties.

Claims

1. Epoxy resin A, represented by the following chemical formula 1, Epoxy resin B, represented by the following chemical formula 2, The epoxy resin C represented by the following chemical formula 3, and hardening agent An epoxy resin composition containing [the specified ingredient]. 【Chemistry 1】 (In formula 1, R １ ~R ４ Each of these independently represents one selected from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and a halogen atom, and X is -CH ２ -, -O-, -S-, -CO-, -C(=O)O-, -OC(=O)-, -NHCO-, -CONH-, -SO ２ (Represents one of the options selected from the given list.) 【Chemistry 2】 (In formula 2, R ５ , R ６ These are, independently, aliphatic hydrocarbon groups with 4 to 12 carbon atoms. 【Transformation 3】 In Formula 3, m is an integer from 0 to 20, R ７ to R １０ each independently represent a hydrogen atom or a glycidyl group represented by the following Chemical Formula 4, and among R ７ to R １０ , at least two groups are glycidyl groups represented by the following Chemical Formula 4.) 【Chemistry 4】

2. The epoxy resin composition according to claim 1, wherein, based on the total mass of epoxy resins contained in the epoxy resin composition, epoxy resin A is 50 to 90% by mass, and / or the sum of epoxy resins B and C is 10 to 50% by mass.

3. The epoxy resin composition according to claim 1 or 2, wherein the ratio Mb / Mc of the content of epoxy resin B in the epoxy resin composition to the content of epoxy resin C in the epoxy resin composition is 0.8 to 3.

5.

4. The epoxy resin composition according to claim 1 or 2, wherein at least one of the epoxy resin B and the epoxy resin C is a biomass-derived epoxy resin.

5. The epoxy resin composition according to claim 1 or 2, wherein the epoxy resin A is a combination of one or more selected from the group consisting of tetraglycidyl-4,4'-diaminodiphenyl ether, tetraglycidyl-4,4'-diaminodiphenylmethane, tetraglycidyl-3,4'-diaminodiphenyl ether, and tetraglycidyl-3,3'-diaminodiphenylmethane.

6. The epoxy resin composition according to claim 1 or 2, wherein the epoxy resin B is an epoxy resin represented by the following chemical formula 2-1. 【Transformation 5】

7. The epoxy resin composition according to claim 1 or 2, wherein the epoxy resin C is an epoxy resin represented by the following chemical formula 3-1. 【Transformation 6】

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

9. A fiber-reinforced composite material comprising a resin cured product obtained by curing the epoxy resin composition according to claim 1 or 2, and a fiber-reinforced substrate.

10. The fiber-reinforced composite material according to claim 9, wherein the fiber-reinforced substrate is a carbon fiber-reinforced substrate.

11. To form an intermediate composite comprising a fiber-reinforced substrate and the epoxy resin composition described in claim 1 or 2, The intermediate composite is cured to form a fiber-reinforced composite material. A method for producing fiber-reinforced composite materials, including [the specified element].

12. Impregnating a fiber-reinforced substrate placed in a mold with the epoxy resin composition according to claim 1 or 2, The fiber-reinforced substrate impregnated with the epoxy resin composition is cured under heat to form a fiber-reinforced composite material. A method for producing fiber-reinforced composite materials, including [the specified element].

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