Epoxy resin composition and cured product thereof

Abstract

To provide an epoxy resin composition enabling production of a cured product having favorable storage stability, rapid curability, thermal resistance, and elastic modulus; and also to provide a cured product of the epoxy resin composition.SOLUTION: An epoxy resin composition comprising: (A) an epoxy resin having a structure of formula (1) (R1 to R4: a hydrogen atom or a hydrocarbon group optionally containing a hetero atom, and may be bonded to each other to form a ring; X: -CH2- or a direct bond); (B) an aromatic epoxy resin having a glycidyl ether group and being free of a glycidyl amino group; and (C) at least one curing agent selected from an amine-adduct latent curing agent and an imidazole-adduct latent curing agent, wherein the content of component (A) is 5 mass% or more and 60 mass% or less in all epoxy resin components.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin composition and a cured product thereof. [Background technology]

[0002] Epoxy resins are used in many applications, mainly in the fields of paint, civil engineering, electricity, and sports, due to their excellent adhesive properties and moldability. Furthermore, their cured products have good electrical properties, heat resistance, and mechanical properties, making them particularly suitable as semiconductor encapsulation materials and matrix resins for fiber-reinforced plastics (FRP).

[0003] Generally, epoxy resin compositions are used by mixing an epoxy resin and a curing agent, but since the viscosity gradually increases immediately after mixing and the impregnation property decreases, which limits the conditions of use, a long pot life (storage stability) after mixing is required from the viewpoint of workability. Also, excellent curability (low-temperature curing property, fast curing property) is required from the viewpoint of productivity.

[0004] To meet the above requirements, epoxy resin curing agents (latent curing agents) that do not react at room temperature after mixing but cure upon heating are used. Examples of latent curing agents include dicyandiamide, dibasic acid dihydrazides, and imidazoles. Among them, amine adduct-type latent curing agents are known as curing agents that can achieve both storage stability and fast curing properties (Patent Document 1).

[0005] Meanwhile, in recent years, there has been a great demand for high heat resistance in a variety of applications, including power semiconductors and FRP. In particular, FRP, which is used as a base material for aircraft and automobiles, also requires a high modulus of elasticity. To increase the glass transition temperature of the cured product, it is common to use a multifunctional epoxy resin. Patent Document 2 proposes an epoxy resin composition that has high heat resistance and excellent storage stability by using a glycidylamine-type epoxy resin, dicyandiamide, and an amine adduct-type latent curing agent. However, with conventional technology, the modulus of elasticity does not increase even when a glycidylamine-type epoxy resin is used. Therefore, there has been a need for the development of an epoxy resin composition that can achieve both a high glass transition temperature and a high modulus of elasticity while maintaining storage stability and fast curing properties. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-203033 [Patent Document 2] Patent Publication No. 2021-91817 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide an epoxy resin composition that has excellent storage stability and fast curing properties, and that can give a cured product that has good heat resistance and elastic modulus, and to provide a cured product thereof. [Means for solving the problem]

[0008] The present invention provides the following epoxy resin composition and cured product. [1] An epoxy resin composition comprising at least the following components (A) to (C), wherein the blending ratio of component (A) in the total epoxy resin components (100% by mass) is 5 to 60% by mass: (A) an epoxy resin having a structure represented by the following formula (1): [ka] (In formula (1), R 1 ~R 4 R is a hydrogen atom or a hydrocarbon group which may contain a heteroatom. 1 ~R 4 may be the same or different and may be bonded to each other to form a ring. X represents -CH2- or a direct bond. (B) Aromatic epoxy resin that does not have a glycidylamino group but has a glycidyl ether group (C) At least one curing agent selected from an amine adduct type latent curing agent and an imidazole adduct type latent curing agent [2] The epoxy resin composition according to [1], further comprising the following component (D): (D) Dicyandiamide or its derivatives [3] The epoxy resin composition according to [1] or [2], wherein the component (B) is at least one epoxy resin selected from the group consisting of bisphenol-type epoxy resins and phenol novolac-type epoxy resins. [4] The epoxy resin composition according to any one of [1] to [3], wherein the curing agent (C) is contained in an amount of 0.1 to 50 parts by mass per 100 parts by mass of all epoxy resin components in the epoxy resin composition. [5] A cured product obtained by curing the epoxy resin composition according to any one of [1] to [4]. [Effects of the Invention]

[0009] The present invention provides an epoxy resin composition that has excellent storage stability and fast curing properties, and can give a cured product that has good heat resistance and elastic modulus, and a cured product thereof. Because of these excellent effects, the composition can be suitably used in fields such as paints, electrical and electronic materials, adhesives, and FRP. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following description and can be modified as desired without departing from the spirit of the present invention. In this specification, when a numerical value or physical property value is enclosed before and after the symbol "~", the value before and after the symbol is used to include the values before and after the symbol. In addition, in this specification, when the lower limit and upper limit of a numerical range are separately described, the numerical range can be a combination of any of the lower limit and upper limit.

[0011] [Epoxy resin composition] An epoxy resin composition according to one embodiment of the present invention (hereinafter may be simply referred to as "epoxy resin composition") is an epoxy resin composition containing components (A), (B), and (C) described below.

[0012] [Component (A)] Component (A) contained in the epoxy resin composition is an epoxy resin represented by the following formula (1) (hereinafter, sometimes referred to as "epoxy resin A"). By using epoxy resin A, an epoxy resin composition with excellent heat resistance can be obtained.

[0013] [ka]

[0014] In formula (1), R 1 ~R 4 R is a hydrogen atom or a hydrocarbon group which may contain a heteroatom. 1 ~R 4 may be the same or different and may be bonded to each other to form a ring. X represents -CH2- or a direct bond. Heteroatoms that the hydrocarbon group may contain include, but are not limited to, nitrogen, oxygen, sulfur, phosphorus, silicon, fluorine, chlorine, bromine, or iodine.

[0015] When X is -CH2-, from the viewpoint of increasing heat resistance, R 1 ~R4 is preferably a hydrogen atom. If X is a direct bond, R 1 ~R 4 The number of hydrocarbon groups among R is not particularly limited, but is preferably 1 or more from the viewpoint of dividing the conjugated system by shifting the dihedral angle between benzene rings and improving reactivity during production. Examples of hydrocarbon groups include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, phenyl, and trifluoromethyl groups. 1 ~R 4 When these are bonded to each other to form a ring, examples include a structure in which these hydrocarbon groups are bonded to each other to form a ring. From the viewpoint of availability, a methyl group, an isopropyl group, a phenyl group, or a trifluoromethyl group is preferred. Among these, a methyl group is particularly preferred from the viewpoint of increasing the thermal decomposition temperature.

[0016] [Physical properties and characteristics of epoxy resin A] The lower limit of the epoxy equivalent of the epoxy resin A is preferably 50 g / eq or more, more preferably 70 g / eq or more, and particularly preferably 100 g / eq or more. When the epoxy equivalent is equal to or more than the lower limit, an appropriate viscosity can be ensured, resulting in good miscibility with other epoxy resins and curing agents. On the other hand, the upper limit of the epoxy equivalent of the epoxy resin A is preferably 500 g / eq or less, more preferably 300 g / eq or less, even more preferably 200 g / eq or less, particularly preferably 150 g / eq or less, and most particularly preferably 130 g / eq or less. By having an epoxy equivalent of not more than the upper limit, the viscosity at high temperatures can be reduced, and handleability can be improved.

[0017] The upper limit of the viscosity of epoxy resin A at 50°C is preferably 500,000 mPa s or less, more preferably 200,000 mPa s or less, even more preferably 130,000 mPa s or less, and particularly preferably 120,000 mPa s or less. When the viscosity at 50°C is equal to or less than the upper limit, uniform mixing becomes easy, and a cured product of uniform quality can be produced. On the other hand, the lower limit of the viscosity of epoxy resin A at 50°C is preferably 100 mPa·s or more, more preferably 500 mPa·s or more, and even more preferably 1,000 mPa·s or more. If the viscosity at 50°C is equal to or more than the lower limit, mixing can be performed by applying shear, making it easy to achieve uniform mixing.

[0018] The epoxy equivalent weight and viscosity at 50°C of epoxy resin A are measured by the method described in the Examples section below.

[0019] Specific examples of the compound represented by the formula (1) include diaminodiphenylmethane tetraglycidyl ether and epoxy resin A-1 represented by the following formula (2), in which Me represents a methyl group.

[0020] [ka]

[0021] Commercially available products of the diaminodiphenylmethane tetraglycidyl ether include jER604 manufactured by Mitsubishi Chemical Corporation and Sumiepoxy ELM-434 manufactured by Sumitomo Chemical Co., Ltd.

[0022] The content of component (A) in the epoxy resin composition is 5 to 60% by mass, based on the total epoxy resin components (100% by mass). It is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass. By keeping the content of component (A) at or below the upper limit of the above range, it is possible to obtain a cured product that has low viscosity but excellent storage stability. Furthermore, by keeping the content of component (A) at or above the lower limit of the above range, it is possible to obtain a cured product that has an excellent balance between heat resistance and rapid curing properties.

[0023] In the present disclosure, the term "total epoxy resin components" refers to the sum of epoxy resin A, epoxy resin B described below, and other epoxy compounds.

[0024] The epoxy resin A may be used either as a single type (one product) or as a combination of two or more types.

[0025] [Component (B)] Component (B) contained in the epoxy resin composition (hereinafter sometimes referred to as "epoxy resin B") is an aromatic epoxy resin that does not have a glycidyl amino group but has a glycidyl ether group. By including epoxy resin B, the viscosity can be easily controlled within an appropriate range while maintaining a high elastic modulus. Therefore, the tackiness of prepregs and the like containing this epoxy resin composition can be easily adjusted, and molded products with fewer voids can be obtained during the production of fiber-reinforced plastics and the like.

[0026] As the epoxy resin B, at least one epoxy resin selected from bisphenol type epoxy resins and phenol novolac type epoxy resins is preferred from the viewpoint of being able to obtain a cured product with an excellent modulus of elasticity.

[0027] Examples of bisphenol type epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol C type epoxy resins, and bisphenol S type epoxy resins.

[0028] Examples of phenol novolac type epoxy resins include phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, and naphthol novolac type epoxy resins.

[0029] The epoxy resin B may be a monofunctional epoxy resin, or may be a bifunctional or higher (multifunctional) epoxy resin.

[0030] The epoxy resin B may be used either as a single type (one product) or as a combination of two or more types.

[0031] Furthermore, the epoxy equivalent of the epoxy resin B is not particularly limited, but from the viewpoint of achieving good viscosity and easy handling, it is preferably in the range of 150 to 300 g / eq, and more preferably in the range of 160 to 200 g / eq.

[0032] The weight ratio of epoxy resin A to epoxy resin B is preferably 5:95 to 60:40, more preferably 5:95 to 50:50, and even more preferably 10:90 to 30:70. By keeping the content of epoxy resin B at or below the upper limit of the above range, a cured product with excellent heat resistance and rapid curing properties can be obtained. Furthermore, by keeping the content of epoxy resin B at or above the lower limit of the above range, a cured product with an excellent balance with elastic modulus can be obtained.

[0033] [Component (C)] Component (C) contained in the epoxy resin composition is at least one curing agent selected from the group consisting of an amine adduct type latent curing agent and an imidazole adduct type latent curing agent. By using component (C), it is possible to achieve both good storage stability and fast curing properties.

[0034] The amine adduct latent curing agent is a compound in which an adduct is added to an amine compound. Examples of the adduct to be added to the amine compound include an isocyanate compound, a urea compound, and an epoxy compound. The imidazole adduct latent curing agent is a compound in which an adduct is added to an imidazole compound. Examples of the adduct to be added to the imidazole compound include an isocyanate compound, a urea compound, a (meth)acrylic compound, and an epoxy compound. The term "curing agent" refers to a substance that contributes to the crosslinking reaction and / or chain extension reaction between epoxy groups in an epoxy resin. In the present disclosure, even substances that are normally called "curing accelerators" are considered to be curing agents as long as they contribute to the crosslinking reaction and / or chain extension reaction between epoxy groups in an epoxy resin.

[0035] The amine adduct type latent curing agent or the imidazole adduct type latent curing agent may be used alone (one product), or two or more types may be used in combination.

[0036] Commercially available products of the amine adduct type latent curing agent or the imidazole adduct type latent curing agent include, for example, Fujicure FXR-1020, Fujicure FXR-1030, Fujicure FXR-1080, and Fujicure FXR-1121 (trade names, all manufactured by T&K TOKA Corporation), Amicure PN-23 and Amicure MY-24 (trade names, all manufactured by Ajinomoto Fine-Techno Co., Ltd.), and ADEKA Hardener EH-5011S and EH-5046S (trade names, all manufactured by ADEKA Corporation).

[0037] The content of component (C) in the epoxy resin composition is preferably 0.1 to 50 parts by mass relative to 100 parts by mass of all epoxy resin components in the epoxy resin composition. It is more preferably 1 to 40 parts by mass, and even more preferably 2 to 30 parts by mass. By keeping the content of component (C) at or below the upper limit of the above range, storage stability can be maintained. By keeping the content of component (C) at or above the lower limit of the above range, excellent rapid curing properties can be achieved, and a sufficient crosslinked structure can be formed during the curing reaction.

[0038] The softening point of component (C) is preferably from 70°C to 250°C, more preferably from 100°C to 200°C, from the viewpoint of curability and storage stability.

[0039] The average particle size of component (C) is preferably 0.1 to 50 μm, more preferably 1 to 30 μm, and particularly preferably 2 to 20 μm.

[0040] [Component (D)] The epoxy resin composition may further contain component (D) in addition to components (A) to (C). The epoxy resin composition contains component (D) dicyandiamide or a derivative thereof. Dicyandiamide and its derivatives have a high melting point and low compatibility with epoxy resins at room temperature, which allows them to maintain excellent storage stability and yield cured products with excellent mechanical properties.

[0041] Commercially available products of dicyandiamide and its derivatives include jER Cure DICY7, jER Cure DICY15, and jER Cure DICY50 (trade names, all manufactured by Mitsubishi Chemical Corporation).

[0042] The content of component (D) in the epoxy resin composition is preferably 0.1 to 20 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 3 to 12 parts by mass, based on 100 parts by mass of all epoxy resin components in the epoxy resin composition.

[0043] [Other epoxy resins] The epoxy resin composition of the present embodiment may further contain other epoxy resins in addition to the epoxy resin A and the epoxy resin B. By including other epoxy resins, it is possible to adjust the viscosity of the epoxy resin composition of the present embodiment and improve the stress resistance, moisture absorption resistance, flame retardancy, and the like.

[0044] Other epoxy resins that can be used in the curable resin composition of the present embodiment include all epoxy resins other than epoxy resin A and epoxy resin B, and specific examples include trisphenolmethane type epoxy resins, anthracene type epoxy resins, phenol-modified xylene resin type epoxy resins, bisphenolcyclododecyl type epoxy resins, bisphenoldiisopropylideneresorcin type epoxy resins, hydroquinone type epoxy resins, methylhydroquinone type epoxy resins, dibutylhydroquinone type epoxy resins, resorcin type epoxy resins, methylresorcin type epoxy resins, biphenol type epoxy resins, tetramethylbiphenol type epoxy resins, dihydroxydiphenyl ether type epoxy resins, epoxy resins derived from thiodiphenols, dihydroxynaphthalene type epoxy resins, dihydroxyanthracene type epoxy resins, dihydroxydihydroanthracene type epoxy resins, dicyclopentadiene type epoxy resins, and the like. Examples of epoxy resins include diene-type epoxy resins, epoxy resins derived from dihydroxystilbenes, phenol aralkyl-type epoxy resins, naphthol aralkyl-type epoxy resins, biphenyl aralkyl-type epoxy resins, terpene phenol-type epoxy resins, dicyclopentadiene phenol-type epoxy resins, epoxy resins derived from phenol-hydroxybenzaldehyde condensates, epoxy resins derived from phenol-crotonaldehyde condensates, epoxy resins derived from phenol-glyoxal condensates, epoxy resins derived from co-condensation resins of heavy oil or pitches with phenols and formaldehydes, epoxy resins derived from diaminodiphenylmethane, epoxy resins derived from aminophenols, epoxy resins derived from xylenediamine, epoxy resins derived from methylhexahydrophthalic acid, and epoxy resins derived from dimer acids. These may be used alone or in any combination of two or more in any blend ratio.

[0045] When the epoxy resin composition of the present embodiment contains another epoxy resin, the content thereof is preferably 0.01 to 60 mass %, more preferably 1 to 40 mass %, and even more preferably 2 to 30 mass %, relative to the total epoxy resin components (100 mass %) in the composition.

[0046] [Other hardeners] The epoxy resin composition of the present invention may contain a curing agent other than component (C) and component (D). However, from the viewpoint of achieving both storage stability and rapid curing properties, it is preferable that the composition does not contain a curing agent other than component (C) and component (D).

[0047] [Other ingredients] The epoxy resin composition may contain other components in addition to the components listed above. Examples of other components include coupling agents, flame retardants, antioxidants, light stabilizers, plasticizers, reactive diluents, pigments, inorganic fillers, organic fillers, thermoplastic resins, thixotropic agents, toughening agents such as core-shell rubber, and mold release agents, which may be appropriately blended as needed. However, this does not in any way preclude the epoxy resin composition of this embodiment from blending components other than those listed above.

[0048] [Check the ingredients] Whether the components (A) to (D) or other compounding components are blended in the curable resin composition according to this embodiment can be confirmed by carrying out qualitative analysis and / or quantitative analysis using a nuclear magnetic resonance spectrometer, a mass spectrometer and / or a chromatograph after separating and purifying the curable resin composition.

[0049] [Cured product] A cured product can be obtained by curing the epoxy resin composition according to this embodiment. "Curing" here means intentionally curing the epoxy resin by heat and / or light, etc. The degree of curing can be controlled depending on the desired physical properties, application, etc.

[0050] The curing method for curing the epoxy resin composition according to this embodiment to form a cured product varies depending on the components and amounts of the components in the epoxy resin composition, the form of the compounded product, etc., but typically involves heating at 50 to 200°C for 5 seconds to 10 hours. This heating may be performed in two stages: primary heating at 50 to 160°C for 5 seconds to 2 hours, and secondary heating at 90 to 200°C, which is 40 to 120°C higher than the primary heating temperature, for 1 minute to 8 hours.

[0051] The presence of epoxy resin A and epoxy resin B in the cured product can be confirmed by decomposing the cured product using an appropriate method and then analyzing it using an appropriate analytical method such as nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy, or various types of chromatography.

[0052] The lower limit of the glass transition temperature of the cured product is preferably 130°C or higher, more preferably 135°C or higher, and particularly preferably 140°C or higher. If the glass transition temperature of the cured product is below this lower limit, the elastic modulus of the cured product may decrease at the actual use temperature. On the other hand, the upper limit of the glass transition temperature is preferably 450°C or lower, more preferably 400°C or lower. If the glass transition temperature of the cured product exceeds this upper limit, the curing temperature or the composition of the cured product may not be compatible with current general processes.

[0053] The lower limit of the flexural modulus of the cured product is preferably 3.2 GPa or more, more preferably 3.3 GPa or more. When the flexural modulus is equal to or greater than the lower limit, rigidity sufficient for practical use can be ensured. The upper limit of the flexural modulus is preferably 10 GPa or less, more preferably 8 GPa or less, and particularly preferably 5 GPa or less. When producing a cured product with a flexural modulus exceeding the upper limit, the curing temperature and composition of the cured product may not be compatible with current general processes.

[0054] [Application] The above-described epoxy resin composition has excellent storage stability and rapid curing properties, while being capable of yielding cured products with good heat resistance and elastic modulus. Because the above-described epoxy resin composition and its cured products exhibit these excellent effects, they can be suitably used in fields such as paints, electrical and electronic materials, adhesives, and fiber-reinforced plastics (FRPs) such as carbon fiber reinforced plastics (CFRPs). Specifically, the epoxy resin composition according to this embodiment can be suitably used in paints, adhesives, prepregs, laminates, semiconductor encapsulants, etc., and the cured products of the resin composition are preferably used in coatings, assemblies, fiber-reinforced plastics (FRPs), semiconductor encapsulants, electrical and electronic materials, etc. [Example]

[0055] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Note that the values of various production conditions and evaluation results in the following examples represent preferred upper or lower limit values in the embodiments of the present invention, and a preferred range may be defined by a combination of the above-mentioned upper or lower limit values and the values in the following examples or values between the examples.

[0056] [Raw materials, etc.] In the following examples and comparative examples, the following raw materials were used. 604: Diaminodiphenylmethane epoxy compound, epoxy equivalent: 120 g / eq, viscosity (50°C): 8,000 mPa·s (jER (registered trademark) 604, manufactured by Mitsubishi Chemical Corporation) 828: Bisphenol A type liquid epoxy resin, epoxy equivalent: 186 g / eq (jER (registered trademark) 828, manufactured by Mitsubishi Chemical Corporation) FXR-1030: Amine adduct type latent curing agent (Fujicure FXR-1030 manufactured by T&K TOKA Corporation) FXR-1121: Imidazole adduct type latent curing agent (Fujicure FXR-1121 manufactured by T&K TOKA Corporation) DICY: Dicyandiamide (jER Cure (registered trademark) DICY7 manufactured by Mitsubishi Chemical Corporation)

[0057] <Epoxy equivalent> The epoxy equivalent of the epoxy resin was measured by potentiometric titration using the glycidylamine correction method in accordance with JIS K 7236. Specifically, a 0.1 mol / L perchloric acid acetic acid solution was added dropwise to a chloroform solution of modified glycidylamine-type epoxy resin to generate a salt of amine and perchloric acid, and the titer V2 at the titration endpoint was obtained. Tetraethylammonium bromide was then added to the system, and the dropwise addition of the 0.1 mol / L perchloric acid acetic acid solution continued. The epoxy equivalent was calculated by subtracting the titer V2 from the titer V1 at the titration endpoint.

[0058] <Viscosity at 50°C> The viscosity of the epoxy resin at 50°C was measured using a rheometer (HAAKE MARS40, manufactured by Thermo Fisher Scientific). The measurement conditions were oscillation mode, a frequency of 1 Hz, and a temperature of 50°C. In this specification, the viscosity at 50°C is the viscosity when the liquid or crystalline compound exists in a supercooled liquid state.

[0059] [Synthesis of epoxy resin A-1] A separable flask equipped with a Dimroth condenser, a nitrogen inlet tube, and a thermocouple was charged with 250 g (1.15 mol) of m-tolidine (4,4'-Diamino-2,2'-dimethylbiphenyl, m-TB-HG manufactured by Seika Corporation), 1199 g (12.95 mol) of epichlorohydrin, 584 g of isopropyl alcohol, and 910 g of water, and the temperature was raised to 30 ° C. The mixture was then heated to 65 ° C. over 90 minutes under normal pressure, and then maintained at 65 ° C. for 90 minutes to complete the addition reaction. In the ring-closing reaction step, 466 g of 48% aqueous sodium hydroxide solution was added dropwise over 120 minutes so that the temperature in the system did not exceed 65 ° C. After the dropwise addition, the mixture was maintained at 65 ° C. for 60 minutes to allow the reaction to proceed. The organic phase was washed with water and then concentrated to obtain the crude target product. The crude product was redissolved in methyl isobutyl ketone (500 g), 48% aqueous sodium hydroxide solution (14.3 g) was added, and the mixture was stirred at 60°C for 1 hour to carry out a ring-closure reaction of the 1,2-chlorohydrin compound to achieve high purity. The organic phase was washed until the aqueous phase became neutral, and then concentrated to obtain Epoxy Resin A-1. The epoxy equivalent of Epoxy Resin A-1 was 115 g / eq.

[0060] [Production and Evaluation of Epoxy Resin Composition and Cured Product] [Example 1] An epoxy resin composition was prepared by kneading a diaminodiphenylmethane epoxy compound (jER® 604, manufactured by Mitsubishi Chemical Corporation) as component (A), a bisphenol A liquid epoxy resin (jER® 828, manufactured by Mitsubishi Chemical Corporation) as component (B), and an amine adduct latent curing agent (Fujicure FXR-1030, manufactured by T&K TOKA Corporation) as component (C) in the proportions shown in Table 1. The gel time and storage stability were evaluated according to the methods described below. This epoxy resin composition was preheated at 80°C for 1 hour and then cured by heating at 130°C for 1.5 hours. A 2 mm-thick plate of the cured product was prepared, and the heat resistance and storage modulus were measured according to the methods described below. The results are shown in Table 1.

[0061] [Example 2] Epoxy resin compositions were prepared by kneading a diaminodiphenylmethane epoxy compound (jER® 604, manufactured by Mitsubishi Chemical Corporation) as component (A), a bisphenol A liquid epoxy resin (jER® 828, manufactured by Mitsubishi Chemical Corporation) as component (B), an imidazole adduct latent curing agent (Fujicure FXR-1121, manufactured by T&K TOKA Corporation) as component (C), and dicyandiamide (DICY7, manufactured by Mitsubishi Chemical Corporation) as component (D) in the proportions shown in Table 1, and the gel time and storage stability were evaluated. Plates of the cured product were also prepared in the same manner as in Example 1, and their heat resistance and storage modulus were measured. The measurement results are shown in Table 1.

[0062] [Example 3] Epoxy resin compositions were prepared by kneading epoxy resin A-1 as component (A), bisphenol A liquid epoxy resin (jER (registered trademark) 828, manufactured by Mitsubishi Chemical Corporation) as component (B), and imidazole adduct latent curing agent (Fujicure FXR-1130, manufactured by T&K TOKA Corporation) as component (C) in the proportions shown in Table 1, and the gel time and storage stability were evaluated. Furthermore, plates of the cured product were prepared in the same manner as in Example 1, and the heat resistance and storage modulus were measured. The measurement results are shown in Table 1.

[0063] [Example 4] Epoxy resin compositions were prepared by kneading epoxy resin A-1 as component (A), bisphenol A liquid epoxy resin (jER® 828, manufactured by Mitsubishi Chemical Corporation) as component (B), imidazole adduct latent curing agent (Fujicure FXR-1121, manufactured by T&K TOKA Corporation) as component (C), and dicyandiamide (DICY7, manufactured by Mitsubishi Chemical Corporation) as component (D) in the proportions shown in Table 1, and the gel time and storage stability were evaluated. Plates of the cured product were also prepared in the same manner as in Example 1, and the heat resistance and storage modulus were measured. The measurement results are shown in Table 1.

[0064] [Comparative Example 1] An epoxy resin composition was prepared by kneading a bisphenol A liquid epoxy resin (jER (registered trademark) 828, manufactured by Mitsubishi Chemical Corporation) as component (B) and an amine adduct latent curing agent (Fujicure FXR-1030, manufactured by T&K TOKA Corporation) as component (C) in the proportions shown in Table 1, and the gel time and storage stability were evaluated. Furthermore, a plate of the cured product was prepared in the same manner as in Example 1, and the heat resistance and storage modulus were measured. The measurement results are shown in Table 1.

[0065] Comparative Example 2 An epoxy resin composition was prepared by kneading a diaminodiphenylmethane epoxy compound (jER® 604, manufactured by Mitsubishi Chemical Corporation) as component (A), a bisphenol A liquid epoxy resin (jER® 828, manufactured by Mitsubishi Chemical Corporation) as component (B), and an amine adduct latent curing agent (Fujicure FXR-1030, manufactured by T&K TOKA Corporation) as component (C) in the proportions shown in Table 1, and the gel time and storage stability were evaluated. Furthermore, a plate of the cured product was prepared in the same manner as in Example 1, and the heat resistance and storage modulus were measured. The measurement results are shown in Table 1.

[0066] Comparative Example 3 Epoxy resin compositions were prepared by kneading a bisphenol A liquid epoxy resin (jER® 828, manufactured by Mitsubishi Chemical Corporation) as component (B), an imidazole adduct latent curing agent (Fujicure FXR-1121, manufactured by T&K TOKA Corporation) as component (C), and dicyandiamide (DICY7, manufactured by Mitsubishi Chemical Corporation) as component (D) in the proportions shown in Table 1, and the gel time and storage stability were evaluated. Furthermore, plates of the cured product were prepared in the same manner as in Example 1, and the heat resistance and storage modulus were measured. The measurement results are shown in Table 1.

[0067] Comparative Example 4 Epoxy resin compositions were prepared by kneading epoxy resin A-1 as component (A), bisphenol A liquid epoxy resin (jER (registered trademark) 828, manufactured by Mitsubishi Chemical Corporation) as component (B), and amine adduct latent curing agent (Fujicure FXR-1121, manufactured by T&K TOKA Corporation) as component (C) in the proportions shown in Table 1, and the gel time and storage stability were evaluated. Furthermore, plates of the cured product were prepared in the same manner as in Example 1, and the heat resistance and storage modulus were measured. The measurement results are shown in Table 1.

[0068] <Gelation time> The viscosity of the obtained epoxy resin composition at 130°C was measured using a rheometer (HAAKE MARS40, manufactured by Thermo Fisher Scientific) (measurement conditions: oscillation mode, frequency 1 Hz, 130°C). From the measurement results, the point at which the storage modulus coincided with the loss modulus was calculated as the gelation time.

[0069] <Storage stability> Within 3 hours after preparation, the viscosity of the resulting epoxy resin composition at 25°C was measured using a rheometer (HAAKE MARS40, manufactured by Thermo Fisher Scientific) (measurement conditions: oscillation mode, frequency 1 Hz, 25°C).The composition was then sealed in a glass bottle and allowed to stand in an environment at 40°C for 1 month, after which it was returned to room temperature and the viscosity at 25°C was measured in the same manner as above.

[0070] <Heat resistance> Heat resistance was measured using a Seiko Instruments Inc. dynamic viscoelasticity measuring device "DMS6100" by raising the temperature from 30 to 300°C at a rate of 5°C / min. The deformation mode was double-bending, and the measurement frequency was 1 Hz. The glass transition temperature (Tg) was defined as the temperature at which the loss tangent tanδ (= loss modulus E'' / storage modulus E') reaches its maximum, and was used as an index of heat resistance.

[0071] <Flexural modulus> A 2 mm thick resin plate was cut into a length of 100 mm and a width of 10 mm, and the cut surface was treated with sandpaper #1200 to prepare a test piece. A bending test was performed on this test piece using an Instron precision universal testing machine, "INSTRON 5582 Model," in accordance with JIS K7161, using a three-point bending jig at a temperature of 23°C and a humidity of 50%RH, to measure the flexural modulus.

[0072] <Evaluation Criteria> [Gelation time] ◯: Gel time is 4 minutes or less ×: Gel time exceeds 4 minutes

[0073] <Evaluation Criteria> [Storage stability] Good: The viscosity after leaving the product at 40°C for one month is less than 1.5 times that of the viscosity before storage at 40°C. ×: The viscosity after standing at 40°C for 1 month is 1.5 times or more higher than the viscosity before storage at 40°C.

[0074] <Evaluation Criteria> [Heat resistance] ◎: Glass transition temperature is 190℃ or higher ◯: Glass transition temperature is 140℃ or higher and lower than 190℃ ×: Glass transition temperature is less than 140°C

[0075] <Evaluation Criteria> [Flexural modulus] ◎: Flexural modulus is 3.5 GPa or more ○: Flexural modulus is 3.3 GPa or more and less than 3.5 GPa ×: Flexural modulus is less than 3.3 GPa

[0076] [Table 1]

[0077] [Evaluation results] As can be seen from the Examples and Comparative Examples, the cured products obtained from epoxy resin compositions containing component (A), component (B), and component (C) in which the blending ratio of component (A) was within a specific range had excellent storage stability and fast curing properties, as well as good heat resistance and elastic modulus.

Claims

1. An epoxy resin composition comprising at least the following components (A) to (C), wherein the blending ratio of component (A) in all epoxy resin components (100% by mass) is 5 to 60% by mass: (A) an epoxy resin having a structure represented by the following formula (1): 【Chemical 1】 (In formula (1), R １ ~R ４ is a hydrogen atom or a hydrocarbon group which may contain a heteroatom. １ ~R ４ may be the same or different and may be bonded to each other to form a ring. ２ represents a - or a direct bond.) (B) Aromatic epoxy resin having no glycidylamino group but having a glycidyl ether group (C) At least one curing agent selected from an amine adduct type latent curing agent and an imidazole adduct type latent curing agent

2. The epoxy resin composition according to claim 1, further comprising the following component (D): (D) Dicyandiamide or its derivatives

3. 3. The epoxy resin composition according to claim 1, wherein the component (B) is at least one epoxy resin selected from the group consisting of bisphenol-type epoxy resins and phenol novolac-type epoxy resins.

4. 3. The epoxy resin composition according to claim 1, wherein the curing agent (C) is contained in an amount of 0.1 to 50 parts by mass per 100 parts by mass of all epoxy resin components in the epoxy resin composition.

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

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